EP4677288A2

EP4677288A2 - Systems including pressure exchangers and associated methods

Info

Publication number: EP4677288A2
Application number: EP24716573.1A
Authority: EP
Inventors: Joseph Michael MARCHETTI; Neelesh SARAWATE; Azam Mihir THATTE; Omprakash Samudrala; Matthew Hans TRUAX
Original assignee: Energy Recovery Inc
Current assignee: Energy Recovery Inc
Priority date: 2023-03-06
Filing date: 2024-03-05
Publication date: 2026-01-14
Also published as: JP2026510337A; CN120936838A

Abstract

A system includes a pressure exchanger (PX) configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The system further includes a first gas cooler, configured to provide working fluid to a first inlet of a heat exchanger and a second inlet of a heat exchanger. The heat exchanger is configured to exchange heat between fluid provided via the first inlet and fluid provided via the second inlet. A first outlet of the heat exchanger provides the first fluid to the PX. A second outlet of the heat exchanger provides the second fluid to the PX. The system further includes a receiver, configured to receive the first fluid and the second fluid from the PX. The system further includes a first compressor, configured to provide working fluid to the first gas cooler.

Description

REFRIGERATION SYSTEMS INCLUDING PRESSURE EXCHANGERS AND

THEIR CONTROL

TECHNICAL FIELD

[0001] The present disclosure relates to control of systems, and, more particularly, control of refrigeration and heat pump systems that include pressure exchangers.

BACKGROUND

[0002] Systems use fluids at different pressures. Systems use pumps and/or compressors to increase pressure of fluid. Energy usage of a fluid handling system may be largely consumed by pumps and/or compressors increasing fluid pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The present disclosure is illustrated by way of example, and not by way of limitation in the figures of the accompanying drawings.

[0004] FIG. 1 A is a schematic diagram of a fluid handling system that includes a hydraulic energy transfer system, according to some embodiments.

[0005] FIG. IB is a schematic diagram of a fluid handling system including a hydraulic energy transfer system, according to some embodiments.

[0006] FIGS. 2A-E are exploded perspective views of pressure exchangers (PXs), according to some embodiments.

[0007] FIG. 3 A is a schematic diagram of a fluid handling system including a PX and a heat exchanger for exchanging heat between two streams of working fluid, according to some embodiments.

[0008] FIG. 3B is a schematic diagram of a fluid handling system that includes a pressure exchanger with an auxiliary receiver, according to some embodiments.

[0009] FIG. 3C is a schematic diagram of a fluid handling system that includes a subcooler and an auxiliary receiver, according to some embodiments.

[0010] FIG. 3D is a schematic diagram of a fluid handling system including a PX, according to some embodiments.

[0011] FIG. 3E is a schematic diagram of a fluid handling system including a PX, according to some embodiments.

[0012] FIG. 3F is a schematic diagram of a fluid handling system including a PX, according to some embodiments. [0013] FIG. 3G is a schematic diagram of a fluid handling system including a PX, according to some embodiments.

[0014] FIG. 4A is a schematic diagram of a fluid handling system including a PX, a subcooler, and various controllers and other components for providing control of the fluid handling system, according to some embodiments.

[0015] FIG. 4B is a schematic diagram of a fluid handling system including sensors and controllers, according to some embodiments.

[0016] FIG. 5A is a flow diagram of a method for providing control of a fluid handling system, according to some embodiments.

[0017] FIG. 5B is a flow diagram of a method for providing control of a refrigeration system, according to some embodiments.

[0018] FIG. 5C is a flow diagram of a method for providing control of a refrigeration system, according to some embodiments.

[0019] FIG. 5D is a flow diagram of a method for providing control of a refrigeration system, according to some embodiments.

[0020] FIG. 5E is a flow diagram of a method for providing control of a refrigeration system, according to some embodiments.

[0021] FIG. 6 is a block diagram illustrating a computer system, according to certain embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

[0022] Embodiments described herein are related to architectures of refrigeration and/or heat pump systems that include pressure exchangers, and control of these systems. For example, architectures may include refrigeration systems, heat pump systems, pressure exchanger systems, fluid handling systems that include a pressure exchanger, heat transfer systems, control systems for carbon dioxide (CO2) refrigeration systems integrated with rotary pressure exchanger, etc., as well as control of such systems. In particular, system architectures as well as associated control modules for controlling, maintaining, adjusting, etc. operation of systems including one or more pressure exchangers are described.

[0023] Systems may use fluids at different pressures. A supply of a fluid to a system may be at lower pressure, and one or more portions of the system may operate at higher pressures. A system may include a closed loop with various fluid pressures maintained in different portions of the loop. These systems may include refrigeration systems, heat pump systems, energy generation systems, fluid transportation systems, etc. Pumps or compressors may be used to increase pressure of fluids of such systems.

[0024] Conventionally, heat transfer systems (e.g., refrigeration systems, heat pump systems, reversible heat pump systems, or the like) use pumps or compressors to increase the pressure of a fluid (e.g., a refrigeration fluid such as carbon dioxide (CO2), R-744, R-134a, hydrocarbons, hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), ammonia (NH3), refrigerant blends, R-407A, R-404A, etc.). Conventionally, separate pumps or compressors mechanically coupled to motors are used to increase pressure of the fluid in any portion of a system including an increase in fluid pressure. Pumps and compressors, especially those that operate over a large pressure differential (e.g., cause a large pressure increase in the fluid), require large quantities of energy. Conventional systems thus expend large amounts of energy increasing the pressure of the fluid (via the pumps or compressors driven by the motors). Additionally, conventional heat transfer systems decrease the pressure of the fluid through expansion valves and/or heat exchangers (e.g., condensers and/or evaporators, etc.). Conventional systems inefficiently increase pressure of fluid and decrease pressure of the fluid. This is wasteful in terms of energy used to run the conventional systems (e.g., energy used to repeatedly increase the pressure of the refrigeration fluid to cause increase or decrease of temperature of the surrounding environment).

[0025] The systems, devices, and methods of the present disclosure enable operation and control of systems (e.g., fluid handling systems, heat transfer systems, refrigeration systems, heat pump systems, cooling systems, heating systems, etc.) including one or more pressure exchangers (PXs). In a system, a PX may be configured to exchange pressure between a first fluid (e.g., a high-pressure portion of a refrigeration fluid in a refrigeration cycle) and a second fluid (e.g., a low pressure portion of the refrigeration fluid in the refrigeration cycle). The PX may receive the first fluid (e.g., a portion of the refrigeration fluid at high pressure) via a first inlet (e.g., a high-pressure inlet) and a second fluid (e.g., a portion of the refrigeration fluid at a low pressure) via a second inlet (e.g., a low-pressure inlet). When entering the PX, the first fluid may be of a higher pressure than the second fluid. The PX may exchange pressure between the first fluid and the second fluid. The first fluid may exit the PX via a first outlet (e.g., a low-pressure outlet) and the second fluid may exit the PX via a second outlet (e.g., a high-pressure outlet). When exiting the PX, the second fluid may have a higher pressure than the first fluid (e.g., pressure has been exchanged between the first fluid and the second fluid). [0026] In some systems, fluid may be pumped, compressed, have pressure increased, or the like at various portions of the fluid handling system. For example, a main compressor (or set of compressors) may perform work to increase pressure of low-pressure fluid to high- pressure fluid, and various other compressors or boosters may be utilized to provide auxiliary adjustments to pressure at other points of the fluid handling system. In some embodiments, one or more adjustments to a fluid flow path may be introduced to reduce a number of pumps or compressors needed, e.g., by utilizing a PX to perform compression conventionally performed by a booster pump.

[0027] In some embodiments, a heat transfer system (e.g., refrigeration system, heat pump system, etc.) may target controlled operating conditions. For example, a refrigeration system may target a particular temperature of a refrigerated zone (e.g., for safe storage of perishable materials such as food, medication, scientific or research materials, or the like); a heat pump system may target a comfortable interior temperature for a home; a system may target a rate of heat exchange between the system and the environment; one or more portions of a system may target an operating temperature, pressure, fluid density, or the like; etc. Operational parameters to maintain target conditions may be dependent on many factors, e.g., ambient temperature; mass, type, and initial temperature of material in a temperature-controlled area; frequency of exchange of material and/or energy between a controlled area and the ambient environment; and the like.

[0028] In some embodiments, the PX may be operable at a range of operating speeds. For example, a rotary PX may be operable at a variety of rotational speeds, a reciprocating PX may be operable at a variety of cycle frequencies, or the like. The PX may be coupled to a motor. The motor may be configured to control an operating speed of the PX. The operating speed of the PX may have an impact on fluid flow rate, fluid pressure in various portions of the fluid handling system, etc. In some embodiments, the motor may drive the PX, e.g., if faster flow rate through the PX is targeted, the motor may speed up operation of the PX. In some embodiments, the motor may serve to inhibit the PX, e.g., if slower flow rate through the PX is targeted, the motor may inhibit motion of the PX to maintain a desired flow rate. A controller may be operatively coupled to the motor of the PX. The controller may receive data collected from one or more parts of the fluid handling system, e.g., pressure data indicative of fluid pressure associated with (e.g., in, exiting from) a condenser of the fluid handling system, flow rate data indicative of flow rate through a portion of the fluid handling system, or the like. The controller may generate a control signal for the motor based on the data received indicative of one or more operating conditions of the fluid handling system. The motor may be configured to adjust an operating speed of the PX based on the control signal.

[0029] In some embodiments, operating speed of the PX may be utilized to maintain one or more conditions of the fluid system. For example, the PX speed may be selected to maintain a target fluid pressure at a component upstream of the PX. The PX speed may further impact other conditions of the system, but may be at least partially unavailable for adjustment due to the impact of the PX speed on multiple conditions and components of the system. Additional control methods may be utilized in maintaining one or more target conditions of a fluid system, that may be further affected by an operating speed of the PX.

[0030] In some embodiments, the fluid system may include one or more control valves, that may be opened or closed to enable a target fluid flow rate, a target upstream fluid pressure, a target downstream fluid pressure, or the like. A control valve may be included in a fluid system, coupled to a high-pressure outlet of the PX. For example, a fluid may leave a high- pressure outlet of the PX, pass through an auxiliary gas cooler, and be provided to a control valve. The control valve may have an adjustable opening, that is adjusted based on one or more inputs, to maintain a target condition of the fluid system. The control valve opening may be adjusted to maintain a target travel distance of the PX.

[0031] Travel distance is a measure of fluid flow into or out of ducts of the PX. For example, fluid may flow from a first inlet into a duct and exchange pressure with a second fluid that entered the duct from an inlet disposed at the opposite side of the duct. The fluid may then, after exchanging pressure, be removed via an outlet disposed at the same side of the duct that the fluid entered. The travel distance is a measure of how far into the duct the first fluid flows before retreating back to the outlet. Travel distance indicates a volumetric flow through the PX, e.g., based on rotational speed of the PX, number of ducts in the PX, and total duct volume of the PX. Two inlets of the PX may have their own associated travel distances. For example, in operation the PX may operate at a first low-pressure travel distance, associated with travel of a fluid provided at a low-pressure inlet of the PX, and a second high-pressure travel distance, associated with travel of a fluid provided at a high- pressure inlet of the PX. A travel distance target may be chosen based on target volume flow through the PX, target energy efficiency, target pressure exchange efficiency, target mixing of the first and second fluids, or the like.

[0032] One or more travel distances of the PX may be adjusted and/or maintained via adjusting operation of components of a fluid transfer system including the PX. For example, the low-pressure inlet travel distance (e.g., a volume of fluid provided to the PX low-pressure inlet as compared to a working volume of the PX) may be maintained by adjusting the opening of the control valve coupled to the high-pressure outlet of the PX. The working volume of the PX depends on the speed of operation of the PX. For example, in a rotary PX, as rotational speed increases, the number of ducts of the PX utilized in a period of time increases. The control valve may be configured to be controlled based on the PX speed to maintain a target low-pressure inlet travel distance in the PX. Further signals may be taken into account in setting an opening of the control valve, such as total system load (e.g., total fluid flow through the system), temperature at one or more gas coolers, etc.

[0033] In some embodiments, the fluid system may include one or more heat exchangers, e.g., to exchange heat between fluids at different points of a fluid handling system. For example, the fluid handling system may include a heat exchanger for cooling a main flow of fluid from a main gas cooler. A portion of fluid provided by the gas cooler may be provided to a cooling fluid channel of the heat exchanger to cool a main portion of fluid. A portion of fluid provided to each fluid channel may be determined by a control valve. A target cooling condition may be monitored, and the portion of fluid provided to the primary or secondary channels of the heat exchanger may be adjusted to achieve a target cooling condition, such as a target subcooling of main fluid provided to the heat exchanger.

[0034] In some embodiments, the fluid handling system may include a control valve associated with a fluid flow path providing fluid to an auxiliary gas cooler. The control valve associated with the auxiliary gas cooler may be opened to determine an amount of fluid that passes through the auxiliary gas cooler, to determine a travel distance of the PX, etc. The control valve associated with the auxiliary gas cooler may be opened an amount based on an opening of another valve on the flow path, e.g., a control valve configured to determine a portion of fluid provided to a secondary channel of a heat exchanger of the fluid handling system. The control valve associated with the auxiliary gas cooler may be opened to enable flow through the valve matching flow through another valve controlled based on other criteria of the fluid handling system.

[0035] In some embodiments, the fluid handling system may include a mechanism for adjusting heat transfer efficiency of one or more heat exchanger, condensers, gas coolers, or the like. For example, an auxiliary gas cooler may include or be associated with one or more fans for increasing heat transfer from the gas cooler to an environment proximate the gas cooler (e.g., an ambient environment). Activation and/or operation of a device adjusting efficiency of heat transfer (e.g., adjusting a fan speed of the auxiliary gas cooler) may be based on temperature of fluid output by the gas cooler. In some embodiments, actions may be taken to achieve and/or maintain a target temperature of fluid output by the auxiliary gas cooler. The target temperature may be based on ambient temperature, e.g., a target fluid temperature after the fluid has passed through the gas cooler may be within a target temperature of the ambient temperature, such as within 5 degrees of the ambient temperature. The target temperature may be based on fluid temperature elsewhere in the fluid handling system, such as fluid output by a main gas cooler. There may be additional architecture, sensors, processing devices, or the like used for maintaining a target or optimal condition of fluid output by the main gas cooler, and a smaller number of sensors or other architecture may be utilized to match fluid output by the auxiliary gas cooler to the fluid output by the main gas cooler.

[0036] In some embodiments, control of a portion of fluid provided to the main and secondary fluid channels of a heat exchanger may be based, instead of other conditions or in addition to other conditions, on conditions of a receiver. For example, subcooling provided to a main flow of fluid in a heat exchanger may decrease an amount of flash gas that accumulates in the receiver, e.g., by reducing temperature of fluid provided to the receiver. In some embodiments, a flash gas valve may be utilized to allow flash gas from the receiver to be directed to other components of the fluid handling system, such as a main compressor. Subcooling of a heat exchanger may be controlled (e.g., by adjusting a portion of fluid provided to main and secondary channels of the heat exchanger) based on reducing flash gas in the receiver. Subcooling of a heat exchanger may be controlled based on sensor readings and/or control signals provided to a flash gas valve, which in turn may be based on flash gas in the receiver.

[0037] In some embodiments, control of a portion of fluid provided to a first and second channel of a heat exchanger may be based, instead or additionally, on a travel distance of the PX. For example, a low-pressure inlet travel distance may be utilized in generating a control signal for a valve that determines a portion of fluid provided to a primary and secondary channel of a heat exchanger. A low-pressure inlet travel distance may be calculated based on measured or estimated low-pressure inlet mass flow rate, low-pressure inlet pressure, and low-pressure inlet temperature. In some embodiments, a control valve determining flow of fluid through an auxiliary gas cooler (e.g., coupled to a high-pressure outlet of the PX) may be controlled based on high-pressure outlet travel distance of the PX. High-pressure outlet travel distance of the PX may be determined based on measurements and/or estimations of high-pressure outlet mass flow rate and high-pressure outlet density. In some embodiments, several different control inputs may be utilized in determining control signals. For example, a function accounting for more than one control condition may be generated, and control signals may be based on multiple control conditions, e.g., for optimizing control based on achieving an optimal combination of conditions. In another example, different condition regimes may cause control to be based on different conditions, such as maintaining a target level of subcooling, conditional upon maintaining a minimum travel distance of the PX and/or a minimum flash gas valve opening.

[0038] In some embodiments, a fluid handling system may include a main receiver and an auxiliary receiver. The auxiliary receiver may be maintained at a higher pressure than the main receiver, e.g., to drive travel between a low-pressure inlet and a low-pressure outlet of the PX. The auxiliary receiver may provide fluid to a low-pressure inlet of the PX. The auxiliary receiver may further be configured to provide fluid via a control valve to the main receiver, e.g., to maintain a target pressure differential between the auxiliary receiver and the main receiver. The auxiliary receiver may be configured to receive a portion of fluid output by a main gas cooler. The auxiliary receiver may be configured to receive fluid output via a high-pressure outlet of the PX, e.g., fluid cooled via an auxiliary gas cooler.

[0039] In some embodiments, a control valve may determine a portion of fluid output by a main gas cooler that is provided to the auxiliary receiver, and a portion provided to a high- pressure inlet of the PX. The control valve may be controlled based on pressure in the auxiliary receiver, e.g., more fluid may be maintained if a pressure drops below a target pressure range, if a pressure differential between the auxiliary receiver and the main receiver is outside a target range, or the like.

[0040] In some embodiments, a control valve may determine a flow of fluid provided from the auxiliary receiver to a low-pressure inlet of the PX. The control of the valve may be based on maintaining a target low-pressure inlet travel distance of the PX. Travel distance may be estimated, e.g., based on valve characteristics such as an estimate of mass flow as a function of valve opening for given inlet conditions. Travel distance may be estimated by determining the low-pressure inlet volumetric flow associated with a target travel distance, e.g., based on PX operational speed. In some embodiments, travel distance may not be directly accounted for, e.g., opening of the control valve may be based on PX operational speed, and/or one or more measured or estimated inlet fluid conditions.

[0041] In some embodiments, a control valve may determine flow of fluid from the auxiliary receiver to the main receiver. Flow may be enabled based on a measured and target pressure differential between the two receivers. Flow may be enabled based on a measured liquid level in the auxiliary receiver, e.g., more liquid may be transferred from the auxiliary receiver to the main receiver if the liquid level of the auxiliary receiver rises above a target threshold.

[0042] Systems, devices, and methods of the present disclosure provide advantages over conventional solutions. Systems of the present disclosure reduce energy consumption compared to conventional systems, e.g., systems that do not include a PX. For example, use of a PX in a heat transfer system of the present disclosure may recover energy stored as pressure and transfer that energy back into the system, reducing the energy cost of operating the heat transfer system. Reduction of energy cost may enable lower compressor speed or power consumption, or less expensive, smaller, and/or lower power compressors to be used in the system.

[0043] Various controllers employed by the system may increase energy efficiency of the system by, for example, minimizing work performed by the compressor to maintain target conditions, for example target temperatures of refrigerated zones associated with the fluid handling system. For example, increased energy efficiency may be achieved by maximizing the transfer of pressure from the first fluid to the second fluid via the PX (e.g., by adjusting fluid flow rates, fluid pressures, PX operating speed, or the like).

[0044] Systems of the present disclosure may reduce complexity of a fluid handling system, by reducing a number of pumps (e.g., boosters) included in the system. For example, architectures of the present disclosure may enable removal of one or more pumps or compressors, e.g., by allowing the PX to perform some pumping or compression operations that, in other architectures, may be performed by a booster. Reduction of a number of pumps or compressors may reduce an equipment cost of the system, reduce a number of components that may be serviced, reduce a number of failure points for reducing system downtime or corrective or preventative maintenance, or the like.

[0045] Systems of the present disclosure may reduce wear on components (e.g., pumps, compressors) compared to conventional systems. Introduction of a PX may reduce the pumping load on one or more pumps/compressors, e.g., may reduce a target pressure differential a compressor is to achieve. One or more controllers (e.g., control system) may improve operation of pumps and compressors by enabling operation at a target pumping speed, e.g., a pumping speed selected to meet target system output (e.g., maintain a target temperature in a heat transfer system) while protecting one or more components of the system (e.g., a minimum viable pumping speed).

[0046] Systems of the present disclosure may protect one or more components from damage. For example, a compressor of the system may be sensitive to the phase of material provided to the compressor (e.g., may be configured to compress a gas, may become damaged if supplied with liquid, etc.). A controller of the system may alter one or more operating parameters of the system (e.g., a fluid flow rate, a pumping speed, PX operating speed, control valve opening, etc.) to maintain a supply of gas to the compressor (e.g., by maintaining a target value of super heat of the gas). Systems of the present disclosure may allow for more flexibility in component selection for a fluid handling system. For example, one or more controllers (e.g., control system) may be operatively coupled, and may work together to maintain one or more operating conditions. For example, a system may include multiple controllers (e.g., control system) operatively coupled to multiple components (e.g., configured to facilitate adjustment of one or more operating parameters of the components). Multiple control signals may be generated to achieve one or more target tasks, e.g., temperature of a region associated with a heat transfer system may be maintained, and load on a pump may be kept within a target range. By utilizing multiple controllers of a system, such goals may be achievable, and/or the user may be able to use a greater selection of components in the system (e.g., may include a pump with a small manufacturer recommended operating pressure range in a system where pressure at the pump can be maintained within that range for a variety of operating conditions).

[0047] Although some embodiments of the present disclosure are described in relation to pressure exchangers, energy recovery devices, and hydraulic energy transfer systems, the current disclosure can be applied to other systems and devices (e.g., pressure exchanger that is not isobaric, rotating components that are not a pressure exchanger, a pressure exchanger that is not rotary, systems that do not include pressure exchangers, etc.).

[0048] Although some embodiments of the present disclosure are described in relation to exchanging pressure between fluid used in fracing systems, desalinization systems, heat pump systems, and/or refrigeration systems, the present disclosure can be applied to other types of systems. Fluids can refer to liquid, gas, transcritical fluid, supercritical fluid, subcritical fluid, and/or combinations thereof.

[0049] In some aspects of the present disclosure, a system includes a pressure exchanger (PX) configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The system further includes a first gas cooler, configured to provide working fluid to a first inlet of a heat exchanger and a second inlet of a heat exchanger. The heat exchanger is configured to exchange heat between fluid provided via the first inlet and fluid provided via the second inlet. A first outlet of the heat exchanger provides the first fluid to the PX. A second outlet of the heat exchanger provides the second fluid to the PX. The system further includes a receiver, configured to receive the first fluid and the second fluid from the PX. The system further includes a first compressor, configured to provide working fluid to the first gas cooler.

[0050] FIG. 1 A illustrates a schematic diagram of a fluid handling system 100A (e.g., heat transfer system, refrigeration system) that includes a hydraulic energy transfer system 110, according to certain embodiments.

[0051] In some embodiments, a hydraulic energy transfer system 110 includes a pressure exchanger (e.g., PX). The hydraulic energy transfer system 110 (e.g., PX, a collection of components including a PX, etc.) receives low pressure (LP) fluid in 120 (e.g., via a low- pressure inlet) from an LP in system 122. The hydraulic energy transfer system 110 also receives high pressure (HP) fluid in 130 (e.g., via a high-pressure inlet) from HP in system 132. The hydraulic energy transfer system 110 (e.g., PX) exchanges pressure between the HP fluid in 130 and the LP fluid in 120 to provide LP fluid out 140 (e.g., via low-pressure outlet) to LP fluid out system 142 and to provide HP fluid out 150 (e.g., via high-pressure outlet) to HP fluid out system 152. Fluid handling system 100A includes booster elimination components 182, e.g., the architecture is designed to include one or more components to enable elimination of one or more pumps or compressors compared to other PX fluid handling systems, such as other PX heat transfer or refrigeration systems. Booster elimination components 182 may include one or more additional heat exchangers, e.g., for providing subcooling for a main/primary flow of fluid in the fluid handling system 100 A.

[0052] A controller may cause an adjustment of flowrates and/or conditions of fluids of HP fluid in 130 and LP fluid out 140 by one or more flow valves, pumps, motors, fans, and/or compressors (not illustrated). The controllers may be configured to cause various operations (e.g., of controllable components included in fluid handling system 100A) to be performed. A controller may be configured to cause actuation of one or more valve. A controller may be configured to cause adjustments to speed of operation of one or more components. A controller may cause other operations of controllable components of fluid handling system 100 A. The controllers may cause one or more valves to actuate. The controllers may activate, deactivate, or adjust operation of one or more pumps. Controllers may activate, deactivate, or adjust operation of components that adjust heat transfer to or from a working fluid of fluid handling system 100 A. For example, controllers may activate fans that increase heat transfer from the working fluid to an ambient environment via one or more gas coolers of fluid handling system 100 A. [0053] In some embodiments, the hydraulic energy transfer system 110 includes a PX to exchange pressure between the HP fluid in 130 and the LP fluid in 120. In some embodiments, the PX is substantially or partially isobaric (e.g., an isobaric pressure exchanger (IPX)). The PX may be a device that transfers fluid pressure between HP fluid in 130 and LP fluid in 120 at efficiencies (e.g., pressure transfer efficiencies, substantially isobaric) in excess of approximately 50%, 60%, 70%, 80%, 90%, or greater (e.g., without utilizing centrifugal technology). High pressure (e.g., HP fluid in 130, HP fluid out 150) refers to pressures greater than the low pressure (e.g., LP fluid in 120, LP fluid out 140). LP fluid in 120 of the PX may be pressurized and exit the PX at high pressure (e.g., HP fluid out 150, at a pressure greater than that of LP fluid in 120), and HP fluid in 130 may be at least partially depressurized and exit the PX at low pressure (e.g., LP fluid out 140, at a pressure less than that of the HP fluid in 130). The PX may operate with the HP fluid in 130 directly applying a force to pressurize the LP fluid in 120, with or without a fluid separator between the fluids. Examples of fluid separators that may be used with the PX include, but are not limited to, pistons, bladders, diaphragms, and/or the like.

[0054] In some embodiments, PXs may be rotary devices. Rotary PXs, such as those manufactured by Energy Recovery, Inc. of San Leandro, Calif., may not have any separate valves, since the effective valving action is accomplished internal to the device via the relative motion of a rotor with respect to end covers. In some embodiments, rotary PXs operate with internal pistons to isolate fluids and transfer pressure with relatively little mixing of the inlet fluid streams. In some embodiments, rotary PXs operate without internal pistons between the fluids.

[0055] In some embodiments, PXs may be reciprocating devices. Reciprocating PXs may include a piston moving back and forth in a cylinder for transferring pressure between the fluid streams. For example, a reciprocating PX may include one or more pressure exchange chambers. The pressure exchange chambers may each include a piston. First fluid at a high pressure may be allowed into one side of a pressure exchange chamber to transfer energy (e.g., via displacement of the piston) to a second fluid at a low pressure on the opposite side of the pressure exchange chamber. The first fluid, now at a low pressure, may then be allowed to drain from the pressure exchange chamber, as the second fluid, now at a high pressure, it utilized for operation of the fluid handling system (e.g., for desalinization, fracing, refrigeration, heat transfer, or the like). Low pressure second fluid may then be allowed to fill the second side of the pressure exchange chamber, and subsequently high pressure first fluid may be introduced into the first side of the pressure exchange chamber to transfer energy to another portion of the second fluid. A reciprocating device may include many pressure exchange chambers operating in a cycle for substantially continuous flow of high pressure second fluid from the device.

[0056] In some embodiments, PXs may be hydraulic turbocharger devices. A hydraulic turbocharger PX may introduce a first fluid at a high pressure to a chamber including a first impeller. The first high pressure fluid may cause the impeller to rotate by transferring energy from the first fluid to the impeller. The first impeller may be coupled to a shaft that is further coupled to a second impeller in a separate chamber. Rotation of the first impeller may cause rotation of the second impeller. The second impeller may be in contact with a second fluid at a low pressure. Rotation of the impeller may transfer energy to the second fluid (e.g., increase pressure of the second fluid).

[0057] Any PX or multiple PXs may be used in the present disclosure, such as, but not limited to, rotary PXs, reciprocating PXs, hydraulic turbocharger PXs, or any combination thereof. In addition, the PX may be disposed on a skid separate from the other components of a fluid handling system 100A (e.g., in situations in which the PX is added to an existing fluid handling system). For example, the PX may be fastened to a structure that can be moved from one site to another. The PX may be coupled to a system (e.g., pipes of a system, etc.) that has been built on-site. The structure to which the PX is fastened may be referred to as a ‘skid.’ [0058] In some embodiments, a motor 160 is coupled to hydraulic energy transfer system 110 (e.g., to a PX). In some embodiments, the motor 160 controls the speed of a rotor of the hydraulic energy transfer system 110 (e.g., to increase pressure of HP fluid out 150, to decrease pressure of HP fluid out 150, etc.). In some embodiments, motor 160 generates energy (e.g., acts as a generator) based on pressure exchanging in hydraulic energy transfer system 110. For example, a pressure differential (e.g., a difference between the pressure of LP fluid in 120 and HP fluid in 130) may drive rotation of a rotary PX, and motor 160 may introduce resistance to that rotation to both slow the rotation and generate electricity.

Alternatively, the motor may act to slow the PX without generating electricity.

[0059] The hydraulic energy transfer system 110 may include a hydraulic turbocharger or hydraulic pressure exchanger, such as a rotating PX. The PX may include one or more chambers and/or channels (e.g., 1 to 100 channels) to facilitate pressure transfer between first and second fluids (e.g., gas, liquid, multi-phase fluid, supercritical fluid, etc.).

[0060] In some embodiments, hydraulic energy transfer system 110 may transfer energy (e.g., pressure) between two fluids of substantially different composition, phase, or the like. For example, a PX of hydraulic energy transfer system 110 may transfer pressure between a first fluid (e.g., pressure exchange fluid, such as a fluid of a first phase such as liquid or supercritical fluid, proppant free fluid, substantially proppant free fluid, lower viscosity fluid, fluid that has lower than a threshold amount of certain chemicals, etc.) and a second fluid that may be of a different phase, have a higher viscosity (e.g., be highly viscous), include more than a threshold amount of certain chemicals (e.g., corrosive chemicals), and/or contain solid particles (e.g., frac fluid containing sand, proppant, powders, debris, ceramics, etc.). By transferring energy from one type of fluid to another, expensive components such as pumps may be protected from coming into contact with fluids that may be harmful to them, such as viscous, corrosive, or abrasive fluids, or fluids of a phase the components are not equipped to handle.

[0061] In some embodiments, hydraulic energy transfer system 110 may transfer energy (e.g., pressure) between two fluids of substantially similar compositions. For example, in some conventional systems, a waste stream of the system may include fluid at a high pressure. Hydraulic energy transfer system 110 may accept as high-pressure input (e.g., HP fluid in 130) the high-pressure waste stream and transfer energy from that stream to a low- pressure work stream (e.g., LP fluid in 120). In some systems, such as a closed refrigeration system, energy may be recovered from a high-pressure portion of a fluid stream to reduce pump and/or compressor requirements on the fluid stream.

[0062] In some embodiments, LP in system 122 receives a gas from LP out system 142. In many embodiments, LP in system 122 receives fluid from a receiver (e.g., flash tank). The receiver may receive LP fluid out 140 output from hydraulic energy transfer system 110. [0063] Fluid handling system 100 A further includes a control module. A control module may include one or more controllers. The control module may be configured to perform any of the methods of FIGS. 5A-E. Controllers of the control module may receive data (e.g., measurement data) from sensors associated with fluid handling system 100 A. The controllers may be configured to generate control signals based on operations parameters (e.g., threshold values, designated operating ranges, target parameter values, etc.) and/or data received from the sensors. The controllers may include a single device performing one or more control tasks, separate devices for each control task (e.g., each controllable component of fluid handling system 100 A), several devices for performing a number of functions each, etc. For example, operations of each of the controllers may be performed by a separate device, or operations of all of the controllers may be performed by a single device, or a combination of separate and combined devices may be employed. Components of a control module may include general computing devices, personal computers (PCs), laptops, mobile phones, tablet computers, netbook computers, microcontrollers, purpose-built controllers (e.g., hardware, circuitry, etc.), proportional integral derivative (PID) controllers (e.g., three-term controllers), a web appliance, or any other device capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that device. A control module may include multiple controllers acting separately (e.g., without input between from one controller to another, without measurement data from one sensor feeding into multiple controllers, etc.). A control module may include multiple controllers working in conjunction with one another, e.g., a target adjustment to operating parameters of the fluid handling system 110A (e.g., as reported by one or more sensor of the system) may include adjustment of operation of one or more components of the system by one or more controllers of the control module.

[0064] Fluid handling system 100 A may additionally include one or more sensors to provide sensor data (e.g., flowrate data, pressure data, velocity data, etc.) associated with the fluids of fluid handling system 100 A. Controllers of fluid handling system 100 A may control one or more flow rates of fluid handling system 100 A, operation of one or more components of fluid handling system 100 A (e.g., operation of motor 160, operation of one or more pumps, etc.), or the like based on the sensor data. In some embodiments, controllers cause one or more flow valves to actuate based on sensor data received.

[0065] The hydraulic energy transfer system 110 may be used in different types of systems, such as fracing systems, desalination systems, refrigeration systems (e.g., FIG. IB), heat pump systems, slurry pumping systems, industrial fluid systems, waste fluid systems, fluid transportation systems, etc.

[0066] Controllers of a control module may provide control signals to interdependent components of fluid handling system 100 A. For example, controllers may provide control signals to motor 160 to control an operating speed of hydraulic energy transfer system 110. An operating speed of hydraulic energy transfer system 110 may further affect conditions in other locations of fluid handling system 100 A. Other components, for example valves, pumps, etc., may be operated to control conditions of fluid handling system 100 A which are affected by the operating speed of hydraulic energy transfer system 110. Controllers may provide signals to various controllable components that are included in fluid handling system 100A. Various components of the subsystems of fluid handling system 100A may be controlled by signals provided by controllers that are based on an operating speed of hydraulic energy transfer system 110.

[0067] FIG. IB illustrates a schematic diagram of a fluid handling system 100B including a hydraulic energy transfer system 110, according to certain embodiments. Fluid handling system 100B may be, for example, a heat transfer system, a refrigeration system, or a heat pump system. Fluid handling system 100B may be configured to cool and/or heat an environment (e.g., an indoor space, a refrigerator, a freezer, etc.). In some embodiments, fluid handling system 100B includes more components, less components, same routing, different routing, and/or the like than that shown in FIG. IB. Some of the features in FIG. IB that have similar reference numbers as those in FIG. 1 A may have similar properties, functions, and/or structures as those in FIG. 1 A.

[0068] In some embodiments, components of fluid handling system 100B may be included to eliminate one or more lift devices to raise pressure in association with one or more of the LP in system 122 or the HP out system 152. HP fluid in 130 may be provided to hydraulic energy transfer system 110 from HP in system 132 (e.g., condenser 138, gas cooler, heat exchanger, etc.). The hydraulic energy transfer system 110 (e.g., PX) may exchange pressure between the LP fluid in 120 and HP fluid in 130 to provide HP fluid out 150 to HP out system 152 (e.g., optional high-pressure lift device, high pressure fluid pump, high pressure compressor, etc.) and to provide LP fluid out 140 to LP out system 142 (e.g., evaporator 144, heat exchanger, etc.). In some embodiments, components of fluid handling system 100B may be included such that a high-pressure lift device is eliminated, e.g., a high-pressure lift device is an optional component in some architectures. The LP out system 142 (e.g., evaporator 144) may provide the fluid to compressor 178 and optionally a low-pressure lift device. The evaporator 144 may provide the fluid to compressor 178 and/or optionally to a low-pressure lift device. In some embodiments a different component may provide fluid to a low pressure lift device, evaporator 144, etc. For example, LP fluid out 140 may be provided to a receiver of flash tank. Liquid output from the flash tank may be provided to evaporator 144. In some embodiments, additional valves, lines, pipes, fluid flow paths, etc., may provide fluid to different devices in different orders and/or combinations. The condenser 138 may receive fluid from compressor 178. A controller may control one or more components of fluid handling system 100B, e.g., including motor 160 and various other controllable components. [0069] The fluid handling system 100B may be a closed system. LP fluid in 120, HP fluid in 130, LP fluid out 140, and HP fluid out 150 may all be a fluid (e.g., refrigerant, the same fluid) that is circulated in the closed system of fluid handling system 100B.

[0070] Fluid handling system 100B may additionally include one or more sensors configured to provide sensor data associated with the system. For example, sensors may report on properties of the fluid at various stages of the system (e.g., various components of the system) such as temperature, pressure, flow rate, density, etc. Sensors may measure properties related to the function of fluid handling system 100B, e.g., a refrigeration system may include one or more temperature sensors reporting on the temperature of the region to be refrigerated. Sensors may measure properties influencing operation of fluid handling system 100B, e.g., a heat transfer system intended to heat a region associated with condenser 138 may measure temperature proximate to evaporator 144, and may use the temperature measurements proximate to evaporator 144 to alter one or more operating parameters of fluid handling system 100B, e.g., to achieve a target output (e.g., temperature), to improve efficiency of operation, or the like.

[0071] A control module 133 may be configured to perform any of the methods described in connection with FIGS. 5A-E. Controllers of fluid handling system 100B may receive sensor data from sensors (e.g., raw sensor data, preprocessed sensor data, average sensor data, data as a difference of a measured value from a target/threshold value, etc.). Controllers of fluid handling system 100B may be configured to generate one or more control signals based on the input sensor data. Control signals may facilitate operation of adjustable components of fluid handling system 100B.

[0072] Fluid handling system 100B may include one or more valves with variable openings. For example, a fluid flow rate may be altered by adjusting an opening of a valve. Valves may be electronically adjustable, e.g., a valve may be an electronic expansions valve (EEV). A valve may be configured to adjust an opening of the valve (e.g., a percent open value) based on a control signal received from a control module 133. Fluid handling system 100B may include one or more pumps, compressors, or the like. Pumps and compressors may be configured with variable run speeds (e.g., motor operation speed, pumping speeds, etc.). Pumps and compressors may be configured to adjust a speed of operation based on a control signal received from a control module 133. Fluid handling system 100B may include motor 160 coupled to a PX of hydraulic energy transfer system 110. Motor 160 may be configured to adjust a speed of operation of the PX based on a signal received from a control module 133. For example, motor 160 may act as a generator by transferring rotational energy of the PX to electrical energy.

[0073] FIGS. 2A-E are exploded perspective views of a rotary PX 40 (e.g., rotary pressure exchanger, rotary liquid piston compressor (LPC)), according to certain embodiments. Some of the features in one or more of FIGS. 2A-E may have similar properties, functions, and/or structures as those in one or more of FIGS. 1 A-B.

[0074] PX 40 is configured to transfer pressure and/or work between a first fluid (e.g., refrigerant, supercritical carbon dioxide, HP fluid in 130) and a second fluid (e.g., refrigerant, superheated gaseous carbon dioxide, LP fluid in 120) with minimal mixing of the fluids. The rotary PX 40 may include a generally cylindrical body portion 42 that includes a sleeve 44 (e.g., rotor sleeve) and a rotor 46. The rotary PX 40 may also include two end caps 48 and 50 that include manifolds 52 and 54, respectively. Manifold 52 includes respective inlet port 56 and outlet port 58, while manifold 54 includes respective inlet port 60 and outlet port 62. In operation, these inlet ports 56, 60 enable the first and second fluids to enter the rotary PX 40 to exchange pressure, while the outlet ports 58, 62 enable the first and second fluids to then exit the rotary PX 40. In operation, the inlet port 56 may receive a high-pressure first fluid (e.g., HP fluid in 130) output from a condenser, and after exchanging pressure, the outlet port 58 may be used to route a low-pressure first fluid (e.g., LP fluid out 140) out of the rotary PX 40 to a receiver (e.g., flash tank) configured to receive the first fluid from the rotary PX 40. The receiver may form a chamber configured to separate the fluid into a gas and a liquid. Similarly, the inlet port 60 may receive a low-pressure second fluid (e.g., low pressure slurry fluid, LP fluid in 120) from a booster configured to receive a portion of the gas from the receiver and increase pressure of the gas, and the outlet port 62 may be used to route a high- pressure second fluid (e.g., high pressure slurry fluid, HP fluid out 150) out of the rotary PX 40. The end caps 48 and 50 include respective end covers 64 and 66 (e.g., end plates) disposed within respective manifolds 52 and 54 that enable fluid sealing contact with the rotor 46.

[0075] Ports of the PX are fluidly coupled to a fluid system. The fluid system includes fluid handling architecture 92. Fluid handling architecture 92 includes a number of components for performing operations, adjusting fluid conditions, providing system control, etc., such as the components described in connection with FIGS. 1 A-B. Fluid handling architecture 92 may include booster elimination components 182, e.g., one or more components that enable removal from or bypass of one or more pumps or compressors of fluid handling architecture 92. For example, components such as heat exchangers and/or receivers may enable elimination of one or more booster pumps, compared to other PX fluid systems. More discussion of architectures including one or more booster elimination components may be found in connection with FIGS 3A-G and FIGS. 4A-B.

[0076] One or more components of the PX 40, such as the rotor 46, the end cover 64, and/or the end cover 66, may be constructed from a wear-resistant material (e.g., carbide, cemented carbide, silicon carbide, tungsten carbide, etc.) with a hardness greater than a predetermined threshold (e.g., a Vickers hardness number that is at least 1000, 1250, 1500, 1750, 2000, 2250, or more). For example, tungsten carbide may be more durable and may provide improved wear resistance to abrasive fluids as compared to other materials, such as alumina ceramics. Additionally, in some embodiments, one or more components of the PX 40, such as the rotor 46, the end cover 64, the end cover 66, and/or other sealing surfaces of the PX 40, may include an insert. In some embodiments, the inserts may be constructed from one or more wear-resistant materials (e.g., carbide, cemented carbide, silicon carbide, tungsten carbide, etc.) with a hardness greater than a predetermined threshold (e.g., a Vickers hardness number that is at least 1000, 1250, 1500, 1750, 2000, 2250, or more) to provide improved wear resistance.

[0077] The rotor 46 may be cylindrical and disposed in the sleeve 44, which enables the rotor 46 to rotate about the axis 68. The rotor 46 may have a plurality of channels 70 (e.g., ducts, rotor ducts) extending substantially longitudinally through the rotor 46 with openings 72 and 74 (e.g., rotor ports) at each end arranged symmetrically about the longitudinal axis 68. The openings 72 and 74 of the rotor 46 are arranged for hydraulic communication with inlet and outlet apertures 76 and 78 (e.g., end cover inlet port and end cover outlet port) and 80 and 82 (e.g., end cover inlet port and end cover outlet port) in the end covers 64 and 66, in such a manner that during rotation the channels 70 are exposed to fluid at high-pressure and fluid at low-pressure. As illustrated, the inlet and outlet apertures 76 and 78 and 80 and 82 may be designed in the form of arcs or segments of a circle (e.g., C-shaped).

[0078] An operating speed of PX 40 may be utilized to control the extent of mixing between the first and second fluids in the rotary PX 40, which may be used to improve the operability of the fluid handling system (e.g., fluid handling systems 100A-B of FIGS. 1A- B). For example, varying the volumetric flow rates of the first and/or second fluids entering the rotary PX 40 allows the operator (e.g., system operator, plant operator) to control the amount of fluid mixing within the PX 40. In addition, varying the rotational speed of the rotor 46 (e.g., via a motor) also allows the operator to control mixing. Three characteristics of the rotary PX 40 that affect mixing are: (1) the aspect ratio of the rotor channels 70; (2) the duration of exposure between the first and second fluids; and (3) the creation of a barrier (e.g., fluid barrier, piston, interface) between the first and second fluids within the rotor channels 70. First, the rotor channels 70 (e.g., ducts) are generally long and narrow, which stabilizes the flow within the rotary PX 40. In addition, the first and second fluids may move through the channels 70 in a plug flow regime with minimal axial mixing. Second, in certain embodiments, the speed of the rotor 46 reduces contact between the first and second fluids. For example, the speed of the rotor 46 (e.g., rotor speed of approximately 1200 revolutions per minute (RPM)) may reduce contact times between the first and second fluids to less than approximately 0.15 seconds, 0.10 seconds, or 0.05 seconds. Third, the rotor channel 70 (e.g., a small portion of the rotor channel 70) is used for the exchange of pressure between the first and second fluids. In some embodiments, a volume of fluid remains in the channel 70 as a barrier between the first and second fluids. All these mechanisms may limit mixing within the rotary PX 40. Moreover, in some embodiments, the rotary PX 40 may be designed to operate with internal pistons or other barriers, either complete or partial, that isolate the first and second fluids while enabling pressure transfer.

[0079] In some embodiments, a speed of operation of the PX may be set (e.g., targeting the properties listed above, or other properties of interest in the fluid system). Properties of the fluid system may be affected by the PX 40 rotational speed. A control module may receive an indication of PX 40 speed of operation (e.g., from a sensor, from a control signal for a controller of PX 40, etc.), and may generate control signals for controllable components of fluid handling architecture 92 which are based on speed of operation of PX 40.

[0080] FIGS. 2B-2E are exploded views of an embodiment of the rotary PX 40 illustrating the sequence of positions of a single rotor channel 70 in the rotor 46 as the channel 70 rotates through a complete cycle. It is noted that FIGS. 2B-2E are simplifications of the rotary PX 40 showing one rotor channel 70, and the channel 70 is shown as having a circular cross- sectional shape. In other embodiments, the rotary PX 40 may include a plurality of channels 70 with the same or different cross-sectional shapes (e.g., circular, oval, square, rectangular, polygonal, etc.). Thus, FIGS. 2B-2E are simplifications for purposes of illustration, and other embodiments of the rotary PX 40 may have configurations different from those shown in FIGS. 2A-2E. As described in detail below, the rotary PX 40 facilitates pressure exchange between first and second fluids (e.g., a particulate-free fluid and a slurry fluid, higher pressure refrigerant and lower pressure refrigerant, etc.) by enabling the first and second fluids to briefly contact each other within the rotor 46. In some embodiments, the PX facilitates pressure exchange between first and second fluids by enabling the first and second fluids to contact opposing sides of a barrier (e.g., a reciprocating barrier, a piston, not shown). In some embodiments, this exchange happens at speeds that result in limited mixing of the first and second fluids. The speed of the pressure wave traveling through the rotor channel 70 (as soon as the channel is exposed to the aperture 76), the diffusion speeds of the fluids, and/or the rotational speed of rotor 46 may dictate whether any mixing occurs and to what extent.

[0081] FIGS. 2B-E include booster elimination components 182, as part of a fluid system fluidly coupled to one or more outlets of PX 40. Booster elimination components 182 may enable removal of one or more pumps or compressors (e.g., a low-pressure booster and/or high-pressure booster) from a fluid handling system, as described in connection with FIG. 1A.

[0082] Controllable components of a fluid handling system coupled to the PX depicted in FIGS. 2B-E may be provided control signals in accordance with any of the methods of FIGS. 5A-E. FIGS. 2B-E depict various stages of operation of PX 40. Operation of PX 40 may be controlled by a control module. For example, the control module may be operatively coupled to a motor of the PX. The control module may send one or more control signals to the motor. The motor may adjust operation of PX 40, e.g., may adjust a speed of rotation of PX 40, a speed of rotation of PX 40, etc. The control module may be operatively coupled to other components of a fluid handling system that affect operation of PX 40. For example, one or more compressors that supply fluid to PX 40 may be controlled by the control module, one or more valves that supply fluid to PX 40 may be controlled by the control module, one or more valves coupled to an outlet of PX 40 may be controlled by the control module, etc. These components may include controllable components described in connection with architectures of FIGS. 3A-G. These controllable components may be associated with control via methods described in connection with FIGS. 5A-E.

[0083] FIG. 2B is an exploded perspective view of an embodiment of a rotary PX 40 (e.g., rotary LPC), according to certain embodiments. In FIG. 2B, the channel opening 72 is in a first position. In the first position, the channel opening 72 is in fluid communication with the aperture 78 in end cover 64 and therefore with the manifold 52, while the opposing channel opening 74 is in hydraulic communication with the aperture 82 in end cover 66 and by extension with the manifold 54. The rotor 46 may rotate in the clockwise direction indicated by arrow 84. In operation, low-pressure second fluid 86 (e.g., low pressure slurry fluid) passes through end cover 66 and enters the channel 70, where it contacts the first fluid 88 at a dynamic fluid interface 90. The second fluid 86 then drives the first fluid 88 out of the channel 70, through end cover 64, and out of the rotary PX 40. However, because of the short duration of contact, there is minimal mixing between the second fluid 86 (e.g., slurry fluid) and the first fluid 88 (e.g., particulate-free fluid). In some embodiments, low pressure second fluid 86 contacts a first side of a barrier (e.g., a piston, not shown) disposed in channel 70 that is in contact (e.g., on an opposing side of the barrier) by first fluid 88. The second fluid 86 drives the barrier which pushes first fluid 88 out of the channel 70. In such embodiments, there is negligible mixing between the second fluid 86 and the first fluid 88. [0084] FIG. 2C is an exploded perspective view of an embodiment of a rotary PX 40 (e.g., rotary LPC), according to certain embodiments. In FIG. 2C, the channel 70 has rotated clockwise through an arc of approximately 90 degrees. In this position, the opening 74 (e.g., outlet) is no longer in fluid communication with the apertures 80 and 82 of end cover 66, and the opening 72 is no longer in fluid communication with the apertures 76 and 78 of end cover 64. Accordingly, the low-pressure second fluid 86 is temporarily contained within the channel 70.

[0085] FIG. 2D is an exploded perspective view of an embodiment of a rotary PX 40 (e.g., rotary LPC), according to certain embodiments. In FIG. 2D, the channel 70 has rotated through approximately 60 degrees of arc from the position shown in FIG. 2B. The opening 74 is now in fluid communication with aperture 80 in end cover 66, and the opening 72 of the channel 70 is now in fluid communication with aperture 76 of the end cover 64. In this position, high-pressure first fluid 88 enters and pressurizes the low-pressure second fluid 86, driving the second fluid 86 out of the rotor channel 70 and through the aperture 80.

[0086] FIG. 2E is an exploded perspective view of an embodiment of a rotary PX 40 (e.g., rotary LPC), according to certain embodiments. In FIG. 2E, the channel 70 has rotated through approximately 270 degrees of arc from the position shown in FIG. 2B. In this position, the opening 74 is no longer in fluid communication with the apertures 80 and 82 of end cover 66, and the opening 72 is no longer in fluid communication with the apertures 76 and 78 of end cover 64. Accordingly, the first fluid 88 is no longer pressurized and is temporarily contained within the channel 70 until the rotor 46 rotates another 90 degrees, starting the cycle over again.

[0087] FIGS. 3A-G and FIGS. 4A-B are schematic diagrams of fluid handling systems 300A-G and 400A-B including PXs, according to certain embodiments. Some of the features in one or more of FIGS. 3A-G may have similar properties, functions, and/or structures as those in one or more of FIGS. 1 A-B and/or one or more of FIGS. 2A-E (e.g., features that have similar names and/or reference numbers). Systems of one or more of FIGS. 3A-G may be used to perform the methods of one or more of FIGS. 5A-E. Some of the features in one or more of FIGS. 3A-G may have similar features, properties, functions, and/or structures as those in one or more of FIGS. 4 A-B. Systems of one or more of FIGS. 4 A-B may be used to perform the methods of one or more of FIGS. 5A-E.

[0088] FIGS. 3A-G and 4A-B depict various fluid handling system architectures (fluid handling systems 300A-G and 400 A-B) and various controllers, according to certain embodiments. The depicted architectures are example architectures, e.g., depicted architectures highlight operations of controllers of the fluid handling systems. Any of the controllers depicted in FIGS. 4A-B may be included in any combination in any architecture design of a fluid handling system. For example, a controller performing operations such as controller 490 of FIG. 4 A may be included in another architecture that does not depict the controller (e.g., fluid handling system 300C of FIG. 3C), a controller performing operations such as controller 394 controlling a bypass valve of FIG. 3B may be included in an architecture similar to that depicted in FIG. 3 A, etc. A fluid handling system including any controller depicted herein (e.g., any controller adjusting operation of a component of a fluid handling and/or energy transfer system including a PX based on sensor data from the system), alone or in any combination, is within the scope of this disclosure. Controllers may be isolated components (e.g., each controller may be a separate device), controllers may be combined components (e.g., operations of two or more controllers may be performed by the same device, control system), etc. Controllers may provide control signals in response to various inputs, e.g., sensor data provided to the controllers. Controllers may provide control signals to adjust properties of the fluid handling systems, e.g., to adjust values of one or more conditions of the fluid handling systems such that the condition values satisfy one or more threshold conditions.

[0089] In some embodiments, devices of fluid handling systems 300A-G and 400 A-B of FIGS. 3A-G and 4A-B may communicate via wired connections. In some embodiments, devices of these fluid handling systems may communicate wirelessly. In some embodiments, devices depicted in FIGS. 4A-B may communicate via a network. For example, controllers of FIGS. 4A-B may receive sensor data via a network and may transmit control signals via the network. In some embodiments, devices of fluid handling systems 400 A-B of FIGS. 4 A-B may communicate via one or more wired networks. In some embodiments, devices of fluid handling systems 400A-B of FIGS. 4A-B may communicate via one or more wireless networks (e.g., personal area networks, wireless local area networks, etc.). In some embodiments, devices of fluid handling systems 400A-B may communicate via some wired and some wireless networks.

[0090] In some embodiments, controllers of fluid handling systems 400A-B may be PID controllers. Controllers of fluid handling systems 400 A-B may calculate an error value (e.g., the difference between a target set point and a measured value). Controllers of fluid handling systems 400A-B may apply a correction (e.g., generate a control signal) based on proportional, integral, and derivative terms of the error value. For example, the proportional term may be based on the difference between the set point value and the measured value, the integral term may be based on past values of the error term integrated over time, and the derivative term may be based on a predicted future trend of the error term based on the current rate of change of the error term. In some embodiments, controllers of fluid handling systems 400A-B may be computing devices. Controllers of fluid handling systems 400A-B may be implemented as software (e.g., executed by a general -purpose computing device), hardware, or a combination of hardware and software. In some embodiments, operation of controllers of fluid handling systems 400A-B may include receiving one or more adjustable settings, parameters, etc. For example, the response (e.g., magnitude of output signal, value of an adjustment instruction included in a control signal, etc.) of a controller may be of variable strength (e.g., for a given difference between a measured value and a target value of a measured property, a controller may have a range of possible output values, and implementation of one of the range of outputs may be responsive to one or more settings and/or parameters of the controller). In some embodiments, a controller may have an associated lookup table, and for a given input (e.g., a difference between a set point and a measured value), the controller may produce an output in accordance with the table. In some embodiments, a controller may perform a calculation including an adjustable parameter (e.g., a user-adjustable parameter, and adjustable setting, etc.), and in response to an input, the controller may generate an output based on the input. In some embodiments, parameters and/or settings of controllers may be selected/adjusted by a user. In some embodiments, parameters and/or settings of a controller may be adjusted by a computer-implemented method, e.g., of the controller, of an associated computing device, or the like.

[0091] In some embodiments, performance of a controller may be tracked (e.g., measured and stored for analysis over time). If a controller causes overshoot (e.g., if a component of a fluid handling system over-corrects responsive to receiving a control signal from the controller, if the measured property value passes through a target value before settling within a threshold of the target value, etc.) above a threshold value (e.g., a percent of the difference between the initial value and the target value, above a threshold value of frequency and/or severity of overshoot, etc.), sensitivity of the controller (e.g., strength of response to a measurement different from a target property value) may be decreased. For example, a controller may generate a control signal responsive to receiving a measurement different from a set point (e.g., a difference between a set point and a measured value exceeding a threshold). The controller may later receive a measurement different from the set point but in the opposite direction (e.g., the control signal may have intended to correct a measured value lower than a set point, and the subsequent measurement may be higher than the set point). Responsiveness of the controller (e.g., a parameter of a calculation that determines the strength of an output relative to an input difference between a set point and a measured value, a table entry determining the severity of action instructed in a control signal based on an input from a sensor, etc.) may be adjusted to reduce the likelihood of an overshoot in future operations. Adjustment to a controller setting may be global, e.g., a parameter or table may be updated such that all future control signals are generated according to the update. Adjustment to a controller setting may not apply globally, e.g., one or more lookup table values may be adjusted while others are left unadjusted (e.g., a lookup table value associated with a range of differences between a set point and a measured value may be adjusted, a lookup table value associated with one or more differences for a range of measured values may be adjusted, etc.), a parameter for use in some situations may be updated (e.g., a list of parameters may be applied for different measured values, different set point values, different values of a difference between a measured value and a set point, etc.), or the like.

[0092] Similarly, if a controller is not sensitive enough (e.g., if property values in the system are slower than desired to reach values within a threshold value of a target value), response of the controller may be increased. For example, a controller may receive a measurement different than a set point (e.g., a controller may be configured to receive pressure measurements from a pressure gauge and may receive a measurement that is different from a set point pressure value by at least a threshold amount). The controller may generate a control signal responsive to receiving the measurement (e.g., the controller may generate a control signal for a valve to open to adjust pressure at the pressure gauge). The controller may subsequently receive a measurement that the pressure has not reached the set point (e.g., the action taken by the valve responsive to the control signal was not sufficient to reduce the difference between the set point and the measured value below a threshold). One or more settings/parameters of the controller may be adjusted to increase the response of the controller (e.g., increase the output signal generated based on an input signal of a given strength, increase the severity of instructions included in a control signal associated with a given difference between a set point and a measured value, etc.) to an input.

[0093] In some embodiments, determining an update to the sensitivity and/or response (e.g., an update to a parameter or setting dictating the strength or severity of an output) of a controller may be performed by a machine learning model. A machine learning model may be trained with input including a target property value, a measured property value, a response of the controller (e.g., a control signal), and/or a result of a component of the system acting on an instruction received by the controller. The machine learning model, once trained, may be configured to receive as input a measured property value and a target value and generate as output an indication of an appropriate action (e.g., a control signal) to be taken by one or more components of the fluid handling system. For example, a machine learning model may be provided with historical data as training data. The machine learning model may be provided with one or more historical property values associated with a property to be corrected in a fluid handling system (e.g., one or more set point values and one or more measured values generated before and after a component of the system performs an action as instructed by a controller) as training input. The machine learning model may further be provided with historical property values after an adjustment to correct the measured property values is made (e.g., one or more measured values, measured after a control signal was generated for one or more components of the system). The machine learning model may be provided with one or more historical control signals (or data indicative of the control signals) as target output. Once trained, the machine learning model may receive as input current property values (e.g., one or more set point values, one or more measured values, etc.) and generate as output a control signal (or data associated with a control signal) that is predicted to bring the one or more measured property values within a threshold difference value of the one or more set point values.

[0094] Fluid handling systems 300A-G and 400A-B may be heat transfer systems. Fluid handling systems 300A-G and 400 A-B may be refrigeration systems. Fluid handling systems 300A-G and 400 A-B may be heat pump systems. Fluid handling systems 300A-G and 400 A- B may be reversible heat pump systems. A reversible heat pump system may include components not pictured in FIGS. 3A-G, for example, a reversing valve (e.g., a 4-way valve to reverse flow). A reversible heat pump system may reverse direction of flow of a coolant fluid in one or more portions of the fluid handling system, e.g., flow through a condenser and/or an evaporator (e.g., outdoor heat exchanging unit and/or indoor heat exchanging unit) may be reversed. A reversible heat pump system may not reverse direction of flow in one or more portions of the fluid handling system, e.g., flow through a compressor or pump may not be reversed. A reversible heat pump system may include additional flow paths, additional valves, etc., utilized for example when flow is reversed. Though additional components and flow paths associated with a reversible heat pump system are not depicted in FIGS. 3A-G, reversible heat pump systems including such components are within the scope of this disclosure.

[0095] FIG. 3A is a schematic diagram of a fluid handling system 300A including a PX 310 and a heat exchanger for exchanging heat between two streams of working fluid, subcooler 315, according to some embodiments. System 300A may be configured to control various components of the system based on sensor data received from sensors of the system. System 300 A may be configured to determine an opening of one or more valves based at least in part on a speed of operation of PX 310. System 300A may be configured to determine an opening of one or more valves based on measured conditions of system 300A. Controls of architectures in connection with this disclosure are discussed in more detail in connection with FIGS. 4A-B.

[0096] PX 310 may be a rotary pressure exchanger. In some embodiments, PX 310 is an isobaric or substantially isobaric pressure exchanger. PX 310 may be configured to exchange pressure between a first fluid and a second fluid. PX 310 may be configured to exchange pressure between a high pressure first fluid (e.g., provided to the PX 310 at a high-pressure inlet, labeled HP-IN) and a low pressure second fluid (e.g., provided to the PX 310 at a low- pressure inlet, LP-IN). PX 310 may decrease the pressure of the first fluid (e.g., for output from PX 310 at a low-pressure outlet, LP-OUT) and increase the pressure of the second fluid (e.g., for output from PX 310 at a high-pressure outlet, HP-OUT). In some embodiments, PX 310 is coupled to a motor (e.g., rotation of a rotor of PX 310 is controlled and/or adjusted by motor. In some embodiments, mass flow (e.g., of the first fluid, of the second fluid, etc.) through PX 310 may be related to a speed of operation of PX 310 (e.g., a speed of rotation of a rotor of a rotary PX). In some embodiments, pressure of fluid (e.g., the first fluid, the second fluid, etc.) in various components of a fluid handling system (e.g., fluid handling systems 300A-G may be related to a speed of operation of PX 310.

[0097] In some embodiments, PX 310 is configured to receive the first fluid at a high pressure (e.g., HP fluid in 130 of FIGS. 1 A-B) via a high-pressure inlet. In some embodiments, PX 310 is configured to receive the second fluid at a low pressure (e.g., LP fluid in 120 of FIGS. 1 A-B) via a low-pressure inlet. Although there is a reference to “high pressure” and “low pressure,” “high pressure” and “low pressure” may be relative to one another and may not connote certain pressure values (e.g., the pressure of the HP fluid in 130 is higher than the pressure of LP fluid in 120). PX 310 may exchange pressure between the first fluid and the second fluid. PX 310 may provide the first fluid via a low-pressure outlet (e.g., LP fluid out 140) and may provide the second fluid via a high-pressure outlet (e.g., HP fluid out 150). In some embodiments, the first fluid provided via the low-pressure outlet is at a low pressure and the second fluid provided via the high-pressure outlet is at a high pressure. PX 310 may act as a high-pressure expansion valve, e.g., fluid that flows through PX 310 (e.g., from a high-pressure inlet to a low-pressure outlet) may expand. PX 310 may transfer pressure from one fluid stream to another, increasing the pressure of one fluid stream. PX 310 may act as both an isentropic (or substantially isentropic) expansion device and a compressor, which may cause transfer of heat, may facilitate one or more operations of a refrigeration cycle, or the like. The compression process of PX 310 may be substantially isenthalpic. [0098] In some embodiments, the first fluid may be a refrigerant fluid in a supercritical state (e.g., supercritical CO2). In some embodiments, the first fluid may be a refrigerant fluid in a liquid state (e.g., liquid CO2). In some embodiments, the second fluid may be a refrigerant fluid in a gaseous state (e.g., gaseous CO2). In some embodiments, the second fluid may be a refrigerant fluid in a two-phase mixture (e.g., a liquid-gas mixture of CO2). In some embodiments, the second fluid may be a refrigerant fluid in a liquid state (e.g., liquid CO2).

[0099] In some embodiments, fluid handling system 300A includes a main gas cooler 329 (e.g., a condenser), an auxiliary gas cooler 327, an evaporator 318, and a main compressor 322. In some embodiments, main gas cooler 329 and/or auxiliary gas cooler 327 may or may not act as condensers, e.g., the fluid handling system may be operated at pressures and temperatures such that fluid does or does not condense in the gas coolers. Any embodiment discussed herein may include a gas cooler that may or may not act as a condenser in one or more applications. In some embodiments, e.g., above the critical point of a fluid, the thermodynamic distinction between gas and liquid of a fluid disappears, and fluid (e.g., fluid in a condenser) may exist in a super critical state (e.g., both input and output fluid of a condenser may be in a supercritical state, one of input or output fluid of a condenser may be in a supercritical state, neither fluids may be in a supercritical state, etc.). In some embodiments, fluid handling system 300A is a refrigeration system. For example, evaporator 318 may facilitate absorption of heat by system 300A from a heat source (e.g., a refrigerated area, a cold reservoir, etc.) to a refrigeration fluid. The heat may be rejected to a heat sink (e.g., the environment, a hot reservoir, etc.) via the main gas cooler 329 and/or auxiliary gas cooler 327. In some embodiments, the refrigeration fluid facilitates heat transfer from an environment associated with the evaporator 318 to an environment associated with the main gas cooler 329. Main compressor 322 of fluid handling system 300A may increase corresponding pressure of the refrigeration fluid along a flow path between the evaporator 318 and the main gas cooler 329. In some embodiments, the refrigeration fluid is CO2 or another refrigeration fluid. The refrigeration fluid may flow substantially in a cycle (e.g., from gas cooler 329 to PX 310 to evaporator 318 to main compressor 322 to gas cooler 329, etc.). [00100] In some embodiments, fluid handling system 300A is a heat pump system. For example, heat may be rejected by fluid at main gas cooler 329 into a target region to be heated (e.g., for heating the interior space of a building). Heat may be absorbed from the environment by the fluid of fluid handling system 300A at evaporator 318 for transfer to the environment of main gas cooler 329. In some embodiments, fluid handling system 300A may be a reversible heat pump.

[00101] In some embodiments, main compressor 322 increases pressure of fluid more than a threshold amount (e.g., main compressor 322 may operate over a pressure differential that is greater than a threshold amount, or the like). For example, main compressor 322 may increase pressure of the fluid by approximately 100-1200 psi, by approximately 500-1100 psi, by approximately 800-1000 psi, by approximately 900 psi, by at least 100 psi, by at least 500 psi, any included range, or the like. In some embodiments, operations of main compressor 322 may be performed by more than one physical device, e.g., multiple compressors, multiple pumps, or the like. Multiple compressors performing operations of main compressor 322 may be arranged in parallel, in series, or a combination of arrangements. Any discussion of main compressor 322 may be generalized to include multiple devices, e.g., by summing energy consumed or calculating total fluid flow through the compressor system taking into account arrangement, specifications, and operating speeds of each compressor of the compressor system.

[00102] A motor or other speed adjusting device may be configured to adjust operation of PX 310 (e.g., by adjusting a speed of operation of the motor). Adjusting speed of operation of PX 310 may be performed responsive to receiving a control signal from a controller. Control of PX 310 may be based on pressure of fluid of the main gas cooler 329. Control of PX 310 may further be based on additional metrics, such as ambient temperature, fluid temperature, target evaporator temperature, efficiency of operation of fluid handling system 300 A, etc. A controller may generate a control signal directed at achieving and/or maintaining a target pressure of main gas cooler 329. The target pressure of main gas cooler 329 may be modified by ambient temperature (e.g., heat sink temperature for rejected heat), for example to achieve optimal energy efficiency, heat transfer, refrigeration, or the like. For example, increasing a speed of operation of PX 310 may increase a flow rate of fluid through PX 310. Increasing a speed of operation of PX 310 may decrease fluid pressure of main gas cooler 329.

[00103] In some embodiments, a target pressure of main gas cooler 329 may be chosen to maximize heat transfer of the system, maximize heat transfer between main gas cooler 329 and the environment, maximize energy efficiency of the system, maximize a coefficient of performance (COP, e.g., a ratio between heat transferred by the system and power expended by pumps/compressors of the system), or the like.

[00104] In some embodiments, a device for adjusting PX speed may act to operate, actuate, or accelerate PX 310. For example, a motor may drive PX 310. A motor may draw power from a power source to drive PX 310. In some embodiments, a motor may act like a generator. For example, PX 310 may be driven by fluid of fluid handling system 300 A (e.g., driven by a pressure differential in the fluid, driven by one or more pumps and/or compressors of the system, etc.). A motor may impart additional resistance to operation of PX 310 (e.g., resistance to rotation of a rotor of a rotary PX), which may cause a speed of operation of PX 310 to decrease. A motor may generate electrical power (e.g., may convert rotational energy of PX 310 into electrical energy).

[00105] In some embodiments, evaporator 318 is a heat exchanger to provide corresponding thermal energy from an environment (e.g., a medium of an environment) to a fluid of fluid handling system 300A. For example, evaporator 318 may receive heat (e.g., thermal energy) from air of the environment and provide the heat to the fluid. In some embodiments, the environment is a refrigerated space such as the inside of a refrigerator or freezer, an interior space (e.g., of a building or vehicle), or any other space that is to be kept cool. For example, the environment can be the interior of a freezer or refrigeration section at a supermarket or warehouse. In some embodiments, evaporator 318 may absorb heat from the environment to be provided to main gas cooler 329, e.g., heating the region around main gas cooler 329 may be a target outcome of fluid handling system 300 A.

[00106] In some embodiments, fluid handling system 300 A may include a secondary evaporator. Fluid handling system 300 A may further include secondary components corresponding to any components of evaporator 318, e.g., input and output lines, valves, gauges, controllers, etc. In some embodiments, the secondary evaporator receives a portion of flow of fluid directed to evaporator 318. For example, the secondary evaporator may receive a portion of the flow from the low-pressure outlet of PX 310, e.g., via receiver 313. In some embodiments, a secondary evaporator may target a different temperature than evaporator 318 (e.g., the evaporators may be associated with refrigeration systems with different target temperatures, such as a refrigerator and freezer). In some embodiments, the two evaporators (e.g., evaporator 318 and the secondary evaporator) may be operated at different fluid pressures. Fluid output by one or more of the secondary evaporators may be directed to one or more components (e.g., valves, expansions valves, pumps, compressors, or the like) to alter the pressure of the output fluid such that the pressures are substantially similar when the output streams of the two evaporators are combined.

[00107] In some embodiments, main gas cooler 329 and/or auxiliary gas cooler 329 is a heat exchanger to provide thermal energy from the fluid of fluid handling system 300A to another environment. For example, main gas cooler 329 may reject heat (e.g., thermal energy) to air of an outside (e.g., exterior) environment. In some embodiments, main gas cooler 329 exchanges thermal energy (e.g., rejects heat) to an outside space. For example, main gas cooler 329 may be placed outside a supermarket or warehouse building (e.g., on a roof of the building) and reject heat to the outside environment. In another example, main gas cooler 329 may be placed in the ground and facilitate the transfer of thermal energy between the fluid and the ground. In some embodiments, main gas cooler 329 rejects heat to an interior space while evaporator 318 absorbs heat from an exterior space (e.g., as in a heat pump configuration that is providing heating to the interior space). Thermal energy rejected from main gas cooler 329 may be used to heat an enclosed (e.g., substantially enclosed) space. [00108] In some embodiments, fluid handling system 300 A may include an auxiliary gas cooler 327. In some embodiments, the auxiliary condenser receives the second fluid from the high-pressure outlet of PX 310, and main gas cooler 329 receives output from main compressor 322. In some embodiments, the auxiliary gas cooler 327 is a heat exchanger that exchanges thermal energy (e.g., heat) between the second fluid and a medium of an environment. In some embodiments, the auxiliary gas cooler 327 exchanges thermal energy between the second fluid and the same environment with which the main gas cooler 329 exchanges thermal energy, such as an exterior space of a building. In other embodiments, the auxiliary condenser exchanges thermal energy between the second fluid and a different environment with which the main gas cooler 329 exchanges thermal energy. In some embodiments, the auxiliary gas cooler 327 operates at a temperature different than main gas cooler 329. In some embodiments, auxiliary gas cooler 327 may operate at a different pressure than main gas cooler 329. For example, auxiliary gas cooler 327 may operate at a lower pressure than main gas cooler 329. Auxiliary gas cooler 327 may operate at a target pressure different than a target pressure of main gas cooler 329, at a target pressure differential compared to main gas cooler 329, or the like. Auxiliary gas cooler 327 may be operated around 20 psi lower in pressure than main gas cooler 329. Auxiliary gas cooler 327 may be operated 15-30 psi below pressure of main gas cooler 329. In some embodiments, the main gas cooler and the auxiliary gas cooler may be provided by the same device, e.g., a gas cooler with multiple fluid channels to accommodate multiple fluid flows. In some embodiments, the main gas cooler and/or the auxiliary gas cooler may be associated with devices for adjusting heat exchanged with the fluid in the gas cooler. For example, main gas cooler 329 and/or auxiliary gas cooler 327 may include or be associated with fans for increasing airflow proximate the gas coolers, for increasing heat transfer from the gas coolers, etc.

[00109] Fluid handling system 300A further includes flash gas valve 320. Fluid handling system 300A may include a flash gas valve 320 to regulate a flow of gas on a flash gas bypass flow path. In some embodiments, flash gas valve 320 is a bypass valve that regulates a flow of gas from a gas outlet of the receiver 313 (e.g., flash tank) to be combined with output of the evaporator 318. In some embodiments, the flow of gas from the receiver 313 flows along the flash gas bypass flow path to bypass the evaporator 318. In some embodiments, the flash gas flow path is between receiver 313 and a location downstream of an outlet of the evaporator 318. The gas flowing along the flash gas bypass flow path may be combined with output of the evaporator 318. The flash gas valve 320 may cause gas collected in the receivers 13 to expand (e.g., decrease in pressure) as the gas flows toward the main compressor 322. The flash gas valve 320 may, in some embodiments, be an adjustable valve. In some embodiments, the flash gas valve 320 is caused to actuate by a controller based on sensor data.

[00110] Fluid handling system 300A may include an expansion valve 316. In some embodiments, expansion valve 316 is disposed along a flow path between receiver 313 and evaporator 318, e.g., coupled between receiver 313 and evaporator 318. Expansion valve 316 may be an adjustable valve (e.g., an electronic expansion valve, a thermostatic expansions valve, a ball valve, a gate valve, a poppet valve, etc.). Expansion valve 316 may be controllable by a user (e.g., a technician, an operator, an engineer, etc.) or by a controller. In some embodiments, the expansion valve 316 is caused to actuate by a controller based on sensor data (e.g., pressure sensor data, flowrate sensor data, temperature sensor data, etc.). In some embodiments, expansion valve 316 is a thermal expansion valve. Expansion valve 316 may actuate (e.g., open and/or close) based on temperature data associated with the evaporator 318 (e.g., temperature of liquid in the evaporator, temperature of gas in the evaporator, temperature of fluid entering the evaporator, temperature of fluid exiting the evaporator, etc.). For example, a pressure-sensitive component (e.g., sensing bulb) of the expansion valve 316 may increase or decrease pressure on a diaphragm of the expansion valve 316, causing a poppet valve coupled to the diaphragm to open or close, thus causing more or less flow of fluid to the evaporator 318, causing more or less expansion of the fluid. The pressure-sensitive component of the expansion valve may be positioned proximate to the downstream end of the evaporator 318 (e.g., proximate the outlet of the evaporator 318, outside evaporator 318, inside evaporator 318, or the like) and may be fluidly coupled to the diaphragm via a fluid line (e.g., a sensing capillary). In some embodiments, expansion valve 316 is controlled and actuated entirely based on electronic commands (e.g., from a controller).

[00111] Fluid handling system 300 A includes subcooler 315. Subcooler 315 may be a heat exchanger, configured to exchange heat between portions of fluid output by main gas cooler 329. Subcooler 315 may include a main or primary fluid channel, coupled to a main cooling flow of working fluid. Subcooler 315 may include a secondary or cooling fluid channel, coupled to a fluid stream to absorb heat from the main flow in subcooler 315. Subcooling valve 312 may be a control valve, e.g., may be opened to a target opening to allow a target flow through the secondary channel of subcooler 315. Subcooling valve 312 may act as an expansion valve, e.g., temperature of fluid provided to subcooling valve 312 may be higher than temperature of fluid provided by subcooling valve 312 to secondary channel of subcooler 315. PX 310 may enable this additional cooling step without loss of efficiency due to additional pumping power required to increase pressure of the secondary cooling fluid, by providing compression of the fluid by exchanging pressure with fluid from the main channel of subcooler 315. Main fluid may be provided by subcooler 315 to a high-pressure inlet of PX 310. Secondary cooling fluid may be provided by subcooler 315 to a low-pressure inlet of PX 310.

[00112] Fluid handling system 300A further includes auxiliary valve 369. Auxiliary valve 369 may be a control valve, e.g., capable of allowing a target fluid flow through the auxiliary valve 369. Auxiliary valve 369 may be an auxiliary control valve. Auxiliary valve 369 may be coupled between a high-pressure outlet of PX 310 and an inlet of receiver 313, e.g., either before or after auxiliary gas cooler 327 (in reference to a fluid flow path).

[00113] Described herein are references to “first fluid” and “second fluid.” In some embodiments, the first fluid and the second fluid are the same type of fluid (e.g., are a refrigeration fluid flowing in a fluid handling system). “First fluid” may refer to fluid flowing through the PX 310 from the high-pressure inlet to the low-pressure outlet of the PX 310 and/or fluid flowing to or from the high-pressure inlet and/or the low-pressure outlet of the PX 310. “Second fluid” may refer to fluid flowing through the PX 310 from the low-pressure inlet to the high-pressure outlet of the PX 310 and/or fluid flowing to or from the low- pressure inlet and/or the high-pressure outlet of the PX 310. [00114] In some embodiments, system 300A is a heat pump system capable of heating and cooling an environment (e.g., an indoor space). In some examples, one of main gas cooler 329 or evaporator 318 is an outdoor unit and the other of main gas cooler 329 or evaporator 318 is an indoor unit. In some examples, main gas cooler 329 is the outdoor unit (e.g., condensing unit) and evaporator 318 is the indoor unit (e.g., disposed in a refrigerated space, such as for storing food, medicine, sensitive chemicals or materials, etc.). The flow of fluid through the main gas cooler 329 and the evaporator 318 may be reversible (e.g., via a reversing valve coupled to the main compressor 322). The reversing valve may cause fluid flow exiting the main compressor 322 to be switchable between being directed towards the inlet of main gas cooler 329 (e.g., outdoor unit) or towards the inlet of the evaporator 318 (e.g., indoor unit). In some embodiments, one or more valves and piping may be used to cause fluid flow to be directed in the same direction through all of the components (e.g., one or more the PX 310, main compressor 322, and/or the like) while reversing fluid flow through the main gas cooler 329 and evaporator 318.

[00115] In some embodiments, a system described herein is a heat pump system capable of heating an environment (e.g., an indoor space). In such a heat pump system, the main gas cooler 329 is placed indoors and the evaporator 318 is placed outdoors. In a heat pump system, the evaporator absorbs heat from the ambient and may vaporize a two-phase refrigerant fluid flowing through the evaporator before sending it to the inlet of the compressor. In some embodiments, to switch from refrigeration or air-cooling system to a heat pump system, a reversing valve may be used to cause the fluid flow exiting the main compressor 322 to be switchable between being directed towards the inlet of the outdoor unit or towards the inlet of the indoor unit. In some embodiments, one or more valves and piping may be used to cause fluid flow to be directed in the same direction through all of the components (e.g., one or more the PX 310, main compressor 322, and/or the like) while switching the fluid flow from indoor unit to outdoor unit.

[00116] In some embodiments, the systems described herein (e.g., systems of one or more of FIGS. 3A-G can be used to heat an interior and/or enclosed space, to cool an interior and/or enclosed space, and/or selectively (e.g., reversibly) heat and cool a space.

[00117] In some embodiments, one or more additional components may be included in a fluid handling system such as fluid handling system 300 A that may bypass or partially bypass PX 310. For example, one or more valves may enable a connection between the output of a primary channel of subcooler 315 to an inlet of receiver 313 that bypasses PX 310. In some circumstances (e.g., under a particular set of fluid and/or ambient conditions), PX 310 may not be utilized or may only partially utilized. For example, under some conditions, an increase of efficiency of the fluid handling system provided by PX 310 may not meet a target threshold, and use of PX 310 may be reduced until a change of conditions occurs. One or more high pressure valves, expansion valves, connections to a parent rack, control valves, or the like may determine a portion of fluid provided to a PX in any of the systems discussed herein. For example, a high-pressure control valve may be coupled between the primary outlet of subcooler 315 and an inlet of receiver 313. This high-pressure control valve may be utilized to determine a portion of fluid output by subcooler 315 provided to a high-pressure inlet of PX 310, and a portion provided to receiver 313 without being provided to PX 310. Fluid may be expanded in such a high-pressure valve, cooled by such a high-pressure valve, etc.

[00118] Additional components may include optional mixer 301. Any of the systems described herein may include one or more mixers for incorporating fluid components that may have different temperatures, densities, phases, or the like. In fluid handling system 300 A, a portion of fluid cooled by bypass valve 312 may be provided to mixer 301, along with at least a portion of fluid output by a secondary or cooling channel of subcooler 315. This may reduce temperature or superheat of a fluid provided to a low-pressure inlet of the PX. This may adjust a phase of fluid provided to the low-pressure inlet of PX 310. Mixer 301 may be provided fluid by one or more control valves, e.g., determining a portion of fluid output by bypass valve 312 that is provided to mixer 301, a portion of fluid output by the cooling channel of subcooler 315 that is provided to mixer 301, etc. Control of these valves may be based on fluid temperature measurements (e.g., proximate the low-pressure inlet of PX 310), fluid pressure measurements, fluid phase, fluid density, or other conditions.

[00119] FIG. 3B is a schematic diagram of a fluid handling system 300B that includes a pressure exchanger (PX 310) with an auxiliary receiver 311, according to some embodiments. In some embodiments, features that have reference numbers that correspond to reference numbers in other figures include similar properties, structures, and/or functionality as those described in other figures. In some embodiments, optional components described in connection with FIG. 3A (e.g., secondary evaporator, a system of compressors in place of main compressor 322, etc.) may also be optional components for fluid handling system 300B. In some examples, features of fluid handling system 300B have similar properties, structures, and/or functionality as fluid handling system 300A of FIG. 3A.

[00120] Fluid handling system 300B may be configured to provide heat transfer (e.g., refrigeration) via circulation of a working fluid (e.g., CO2). Fluid handling system 300B may be configured to perform operations to adjust one or more components of fluid handling system 300B based on sensor data generated by sensors of fluid handling system 300B. In some embodiments, fluid handling system 300B may perform operations to achieve and/or maintain a target temperature of a target environment, such as an environment proximate evaporator 318 and/or second evaporator 319. Fluid handling system 300B may achieve a target temperature proximate evaporator 318 (e.g., food refrigeration temperatures, first target refrigeration temperature) and a second target temperature proximate second evaporator 319 (e.g., freezer temperatures, second target refrigeration temperature).

[00121] In some embodiments, fluid handling system 300B may receive data indicative of conditions of the fluid handling system 300B, which may include working fluid conditions, ambient conditions, conditions proximate evaporators and/or gas coolers, etc. Fluid conditions may include temperature, pressure, mass flow rate, density, liquid level of a receiver, etc. Fluid handling system 300B may receive temperature data and/or other condition data from one or more sensors indicative of conditions of a fluid of fluid handling system 300B. Fluid handling system 300B may actuate one or more valves (e.g., bypass high- pressure valve 348) based on the temperature data. Fluid handling system 300B may adjust one or more components to achieve and/or maintain a target fluid temperature, target fluid subcooling, or the like.

[00122] Fluid handling system 300B may include a bypass high-pressure valve 348. Bypass high-pressure valve 348 may be an expansion valve or a flow control valve. In some embodiments, bypass high-pressure valve 348 selectively regulates a flow of fluid from the outlet of main gas cooler 329 (e.g., fluid discharged by main gas cooler 329) to auxiliary receiver 311, e.g., in parallel with the PX 310. In some embodiments, bypass high-pressure valve 348 can be actuated to selectively regulate the flow of fluid. Bypass high-pressure valve 348 may selectively provide a portion of fluid output by the main gas cooler 329 to the auxiliary receiver 311. For example, high-pressure bypass valve 348 can be actuated to be further opened to flow more fluid from the main gas cooler 329 to the auxiliary receiver 311, or bypass high-pressure valve 348 can be actuated to be further closed to flow less fluid from the main gas cooler 329 to the auxiliary receiver 311. The fluid may expand as the fluid flows through bypass high-pressure valve 348, causing a decrease in pressure and/or temperature of the fluid.

[00123] In some embodiments, main gas cooler 329 may act as a condenser. In some embodiments, the fluid handling system may be operated at pressured and temperatures where fluid does or does not condense in main gas cooler 329. Any embodiment discussed herein may include a condenser that may act as a gas cooler in one or more applications. [00124] Fluid handling system 300B may include a receiver 313 (e.g., a flash tank). In some embodiments, receiver 313 is a receiver configured to receive a flow of fluid (e.g., first fluid) output from the low-pressure outlet of the PX 310. Receiver 313 may form a chamber to collect the first fluid from the first outlet of the PX 310. Receiver 313 may receive the first fluid in a two-phase state (e.g., liquid and gas), transcritical fluid, supercritical fluid, subcritical fluid, and/or combinations thereof. Receiver 313 may further receive fluid flow from auxiliary receiver 311, e.g., via a low-pressure control valve. In some embodiments, receiver 313 (e.g., flash tank) is a tank constructed of welded sheet metal. Receiver 313 may include one or more flash tank inlets for receiving fluid and one or more flash tank outlets for discharging fluid (e.g., a gas outlet and a liquid outlet). The first fluid (at a low pressure) may separate into gas and liquid inside the receiver 313 (e.g., indicated by the liquid surface depicted in FIG. 3B). The liquid of the first fluid may settle in the bottom of the receiver 313 while the gas of the first fluid may rise to the top of the receiver 313. The liquid may flow from receiver 313 towards evaporator 318 (e.g., via expansion valve 316). Liquid may flow from receiver 313 toward second evaporator 319, e.g., via secondary expansion valve 317. The chamber of receiver 313 may be maintained at a set pressure. The pressure may be set by a user (e.g., an operator, a technician, an engineer, etc.) and/or by a controller. In some embodiments, the pressure of the receiver 313 is controlled by one or more valves (e.g., expansion valve 316, flash gas valve 320, a pressure regulator valve, a safety valve, etc.). In some embodiments, the receiver 313 includes at least one pressure sensor (e.g., pressure transducer). In some embodiments, a liquid level of receiver 313 may be monitored (e.g., to prevent liquid from being routed through flash gas valve 320). In some embodiments, a pressure differential between receiver 313 and auxiliary receiver 311 may be maintained, e.g., a target pressure differential, such as a 50 PSI differential, may be maintained between auxiliary receiver 311 and receiver 313.

[00125] Fluid handling system 300B may include an expansion valve 316. Fluid handling system 300B may include secondary expansion valve 317. In some embodiments, expansion valve 316 is disposed along a flow path between receiver 313 and evaporator 318, e.g., coupled between receiver 313 and evaporator 318. Secondary expansion valve 317 may be coupled between receiver 313 and second evaporator 319. Expansion valve 316 may be an adjustable valve (e.g., an electronic expansion valve, a thermostatic expansions valve, a ball valve, a gate valve, a poppet valve, etc.). Expansion valve 316 may be controllable by a user (e.g., a technician, an operator, an engineer, etc.) or by a controller. In some embodiments, the expansion valve 316 is caused to actuate by a controller based on sensor data (e.g., pressure sensor data, flowrate sensor data, temperature sensor data, etc.). In some embodiments, expansion valve 316 is a thermal expansion valve. Expansion valve 316 may actuate (e.g., open and/or close) based on temperature data associated with the evaporator 318 (e.g., temperature of liquid in the evaporator, temperature of gas in the evaporator, temperature of fluid entering the evaporator, temperature of fluid exiting the evaporator, etc.). For example, a pressure-sensitive component (e.g., sensing bulb) of the expansion valve 316 may increase or decrease pressure on a diaphragm of the expansion valve 316, causing a poppet valve coupled to the diaphragm to open or close, thus causing more or less flow of fluid to the evaporator 318, causing more or less expansion of the fluid. The pressuresensitive component of the expansion valve may be positioned proximate to the downstream end of the evaporator 318 (e.g., proximate the outlet of the evaporator 318, outside evaporator 318, inside evaporator 318, or the like) and may be fluidly coupled to the diaphragm via a fluid line (e.g., a sensing capillary). In some embodiments, expansion valve 316 is controlled and actuated entirely based on electronic commands. Operations and control of secondary expansion valve 317 may be similar, e.g., in reference to conditions of fluid of second evaporator 319.

[00126] Fluid handling system 300B may include a flash gas valve 320 to regulate a flow of gas on a flash gas bypass flow path. In some embodiments, flash gas valve 320 is a bypass valve that regulates a flow of gas from a gas outlet of the receiver 313 to be combined with output of the evaporator 318. In some embodiments, the flow of gas from the receiver 313 flows along the flash gas bypass flow path to bypass the evaporator 318. In some embodiments, the flash gas flow path is between receiver 313 and a location downstream of an outlet of the evaporator 318. The gas flowing along the flash gas bypass flow path may be combined with output of the evaporator 318. The flash gas valve 320 may cause gas collected in the receiver 313 to expand (e.g., decrease in pressure) as the gas flows toward the main compressor 322. The flash gas valve 320 may, in some embodiments, be an adjustable valve. In some embodiments, the flash gas valve 320 is caused to actuate by a controller based on sensor data.

[00127] In some embodiments, fluid handling system 300B further includes auxiliary receiver 311. Auxiliary receiver 311 may be maintained at a pressure higher than receiver 313. In some embodiments, auxiliary receiver 311 may be maintained to have a target pressure differential above receiver 313, e.g., a differential of 50 PSI, a differential between 40 and 60 PSI, a differential between 20 and 100 PSI, any sub-range, or another target pressure differential between auxiliary receiver 311 and receiver 313. Auxiliary receiver 311 may be maintained at a higher pressure than receiver 313 to drive fluid flow through portions of fluid handling system 300B. For example, a pressure differential may be maintained between the low-pressure outlet of the PX and the low-pressure inlet of the PX, e.g., to drive fluid flow into the low-pressure inlet of the PX. Maintaining a pressure differential between the receiver 313 and the auxiliary receiver 311 may enable fluid flow through the PX.

[00128] In some embodiments, a pressure of the auxiliary receiver 311 may be maintained to achieve a targe flow rate through the PX. For example, a pressure differential between receiver 313 and auxiliary receiver 311 may be maintained such that a target flow rate into a low-pressure inlet, out of a high-pressure outlet, or out of a low-pressure outlet of the PX is maintained. The target flow rate may further be based on other conditions of fluid handling system 300B, such as a target efficiency, target PX operational speed, one or more fluid properties of a working fluid of fluid handling system 300B, or another property of fluid handling system 300B. A flow rate may be estimated by various properties of the fluid handling system 300B (e.g., fluid conductance estimates based on temperature and pressure measurements, or the like). A flow rate may be measured, e.g., utilizing a mass flow meter, density measurements (such as by a Coriolis flow meter), or the like.

[00129] In some embodiments, a low-pressure outlet of PX 310 may be directly connected to receiver 313, e.g., may be maintained at the same pressure as receiver 313. The low- pressure inlet of PX 310 may be directly connected to auxiliary receiver 311, e.g., may be maintained at the same pressure as auxiliary receiver 311. A pressure differential between a low-pressure inlet of PX 310 and a low pressure outlet of PX 310 may drive flow through PX 310. The auxiliary receiver 311 may enable driving of low pressure flow of PX 310 due to the differential, and may eliminate the need for a low-pressure lift device such as a low pressure booster to drive fluid to the low-pressure inlet of the PX 310.

[00130] Fluid handling system 300B includes bypass high-pressure valve 348. Bypass high- pressure valve 348 may optionally be included in a fluid handling system including two receivers. Bypass high-pressure valve 348 may be configured to provide a portion of fluid output by main gas cooler 329 to auxiliary receiver 311. Bypass high-pressure valve 348 may be configured to maintain or achieve a target pressure (or pressure range) of auxiliary receiver 311. For example, bypass high-pressure valve 348 may be configured to allow more fluid to flow to auxiliary receiver 311 if a sensor determines that pressure of auxiliary receiver 311 falls below a threshold. Bypass high-pressure valve 348 may be controlled to achieve a target pressure condition of auxiliary receiver 311.

[00131] Fluid handling system 300B includes a first low-pressure control valve 386 and second low-pressure control valve 387. First low-pressure control valve 386 may be configured to provide fluid from auxiliary receiver 311 to receiver 313. Second low-pressure control valve 387 may be configured to provide fluid from auxiliary receiver 311 to a low- pressure inlet of the PX 310. In some embodiments, the first low-pressure control valve 386 may be an on/off valve.

[00132] In some embodiments, first low-pressure control valve 386 may be utilized for maintaining a target pressure differential between receiver 313 and auxiliary receiver 311. Auxiliary receiver 311 may be maintained at a higher pressure than receiver 313. First low- pressure control valve 386 may be opened to reduce a pressure differential between auxiliary receiver 311, and receiver 313.

[00133] In some embodiments, first low-pressure control valve 386 may be utilized for maintaining a target level of liquid in auxiliary receiver 311. When a liquid level detected in auxiliary receiver 311 exceeds a target threshold (e.g., a target portion of the capacity of auxiliary receiver 311), first low-pressure control valve 386 may be opened to enable fluid flow to receiver 313. When a liquid level detected in auxiliary receiver 311 falls below a targe threshold, first low-pressure control valve 386 may be closed to reduce flow from auxiliary receiver 311.

[00134] Fluid handling system 300B includes second low-pressure control valve 387.

Second low-pressure control valve 387 may be configured to provide fluid from auxiliary receiver 311 to a low-pressure inlet of PX 310. Second low-pressure control valve 387 may be utilized to control a low-pressure inlet travel distance of PX 310. Second low-pressure control valve 387 may be actuated to achieve and/or maintain a target low-pressure inlet travel distance of PX 310, e.g., a 110% travel distance.

[00135] In some embodiments, second low-pressure control valve 387 may be disposed between a low-pressure outlet of PX 310 and receiver 313. In some embodiments, a valve may be disposed in both locations, e.g., a control valve disposed between auxiliary receiver 311 and low-pressure inlet of PX 310, and a control valve disposed between a low-pressure outlet of PX 310 and receiver 313. In some embodiments, placement of a control valve between a low-pressure outlet of PX 310 and receiver 313 may enable control of pressure of fluid at the low-pressure inlet of PX 310. Placement of a control valve between lower- pressure outlet of PX 310 and receiver 313 may enable control of pressure at the low-pressure inlet of PX 310, independent of pressure of the receiver 313. Increased fluid density at the low-pressure inlet of PX 310 may increase mass boost ratio, e.g., a maximum mass flow that can be compressed through PX 310. In some embodiments, some components of fluid handling system 300B may be a pre-existing system (e.g., parent rack), to which a PX system is added. Control of components of a parent rack may be difficult, inconvenient, or impossible to adjust upon introduction of the PX system. Such a valve may enable control of density of fluid provided to the PX without adjusting any controls of the parent rack.

[00136] FIG. 3C is a schematic diagram of a fluid handling system 300C that includes a subcooler 315, and an auxiliary receiver 311, according to some embodiments. Features that have reference numbers that correspond to reference numbers in other figures may include similar properties, structures, and/or functionality as those described in other figures. In some embodiments, optional components described in connection with FIGS. 3A-B may also be optional components for fluid handling system 300C. Features of fluid handling system 300B may have similar properties, structures, and/or functionality as fluid handling systems 300A- B.

[00137] Fluid handling system 300C may be configured to provide heat transfer (e.g., refrigeration) via circulation of a working fluid (e.g., CO2 of one or more phases, such as liquid, gas, or supercritical fluid). Fluid handling system 300C may be configured to perform operations to adjust one or more components of fluid handling system 300C based on sensor data generated by sensors associated with fluid handling system 300C. Fluid handling system 300C may perform operations to achieve and/or maintain a target temperature of one or more environments, such as a building interior or freezer case of a grocery store. Fluid handling system 300C may perform operations to achieve and/or maintain target conditions of the fluid handling system, such as fluid temperature, pressure, density, liquid level, or the like at various locations of fluid handling system 300C. Fluid handling system 300C may adjust one or more components to achieve target conditions, such as actuating valves, adjusting a motor of PX 310, adjusting fan speeds, adjusting compressor speeds, or the like.

[00138] Fluid handling system 300C includes bypass high-pressure valve 348. Bypass high- pressure valve 348 may determine, at least in part, flow of working fluid into auxiliary receiver 311. Bypass high-pressure valve 348 may selectively provide a portion of fluid output by the main gas cooler 329 to auxiliary receiver 311.

[00139] In some embodiments, main gas cooler 329 may act as a condenser. In some embodiments, the fluid handling system may be operated at pressured and temperatures where fluid does or does not condense in main gas cooler 329. Any embodiment discussed herein may include a condenser that may act as a gas cooler in one or more applications. [00140] Fluid handling system 300C further includes receiver 313. Receiver 313 may receive fluid from a low-pressure outlet of PX 310, and from auxiliary receiver 311. Receiver 313 may provide fluid to evaporator 318 for absorbing heat from an environment proximate evaporator 318, and/or to main compressor 322 via flash gas valve 320. Auxiliary receiver 311 and receiver 313 may enable separation of phases of working fluid of fluid handling system 300C.

[00141] Components and operations of components, such as first low-pressure control valve 386, second low-pressure control valve 387, auxiliary valve 369, and bypass high-pressure valve 348 may share one or more features with corresponding components of FIG. 3B. For example, first low-pressure control valve 386 may be controlled based on a pressure of auxiliary receiver 311, a pressure of receiver 313, a pressure differential between the receivers, a liquid level of auxiliary receiver 311, etc. Second low-pressure control valve 387 may be controlled based on a low-pressure inlet travel distance. Control of auxiliary valve 369 may be based on high-pressure outlet travel distance. Control of bypass high-pressure valve 348 may be based on auxiliary receiver pressure. In some embodiments, a low-pressure valve may be included between the low-pressure outlet of PX 310 and receiver 313, instead of or in addition to low-pressure control valve 387.

[00142] Fluid handling system 300C further includes subcooler 315. Subcooler 315 may receive a portion of fluid to a secondary or cooling fluid channel for exchanging heat with fluid output by main gas cooler 329. A secondary or cooling fluid channel of subcooler 315 may receive fluid from auxiliary gas cooler 327, which may receive fluid from a high- pressure outlet of PX 310. In some embodiments, e.g., an architecture such as fluid handling system 300C, which lacks subcooling valve 312 of FIG. 3 A, subcooling may be uncontrolled, e.g., there may not be a control signal associated with monitoring and/or adjusting subcooling performed by subcooler 315.

[00143] Further components of fluid handling system 300C, e.g., PX 310, main compressor 322, expansions valve 316, etc., may perform functions corresponding to their functions as described in connection with fluid handling systems 300A-B of FIGS. 3A-B.

[00144] FIG. 3D is a schematic diagram of a fluid handling system 300D including a PX 310, according to some embodiments. In some embodiments, fluid handling system 300D is a boosterless PX architecture that has low-pressure (LP) fluid out (LPout) dropping into MT (medium temperature) suction (e.g., outlet of evaporator 318). [00145] The flow may split after main gas cooler 329 to produce two streams. The first stream may proceed to high-pressure (HP) fluid in (HPin) of PX 310 and may expand to lower pressure to become cold two-phase liquid gas mixture at LPout of PX 310. The LPout stream proceeds via heat exchanger 370 (HX1) and absorbs heat the second stream (from the flow split from main gas cooler 329) and converts all substantially liquid to gas. The low- pressure gas stream may then drop the pressure further through LP valve 364 to substantially the same pressure as evaporator pressure and proceeds to the inlet of main compressor 322 (e.g., the MT compressor suction of main compressor 322).

[00146] The cooled second stream in heat exchanger 370 (HX1) may expand to low pressure through auxiliary expansion valve 375 and may become a cold two phase liquid-gas mixture. This may reject more heat in heat exchanger 372 (HX2) to the exit flow of the evaporator 318 (e.g., medium temperature (MT) evaporator) to reduce gas mass fraction and increase liquid mass fraction. The reduced flash gas two-phase stream may then proceed to the receiver 313 (e.g., flash tank).

[00147] Flash gas from receiver 313 (e.g., flash tank) may be directed through the LP fluid in (LPin) port of PX 310. Since LPout pressure may now be lower than pressure of receiver 313 that is discharged to main compressor 322 (e.g., to MT compressor suction pressure), the differential pressure between LPin and LPout ports of PX drives the flow through LPin port ofPX 310.

[00148] LPin flow may be compressed to high pressure by the PX 310 and may exit through the HP fluid out (HP out) port. The output of HP out of PX 310 may proceed to auxiliary gas cooler 327 to reject heat via auxiliary gas cooler 327 and become cooler. The fluid exiting auxiliary gas cooler 327 may drop pressure across auxiliary valve 369 and may become cold two-phase liquid gas mixture that further rejects heat in heat exchanger 374 (HX3) to colder fluid exit flow from second evaporator 319 (e.g., low temperature (LT) evaporator). This reduces gas mass fraction and increases liquid mass fraction. This reduces flash gas two- phase flow that then proceeds to receiver 313 (e.g., flash tank).

[00149] Heat exchanger 372 (HX2) may provide superheated fluid to the exit of evaporator 318 (e.g., MT evaporator exit) that may allow raising the pressure of the evaporator 318 (e.g., MT evaporator pressure) while still meeting suction superheat requirement of main compressor 322 (e.g., MT compressor suction superheat requirement). This raised pressure of evaporator 318 (e.g., raised MT evaporator pressure) may reduce the energy consumption of main compressor 322 (e.g., MT compressor’s energy consumption) for the same amount of heat absorbed and this may further increase energy efficiency of fluid handling system 300D. [00150] Heat exchanger 374 (HX3) may provided superheated fluid to the exit of second evaporator 319 (e.g., LT evaporator exit) and this may allow raising the pressure of evaporator 319 (e.g., LT evaporator pressure) while still meeting the suction superheat requirement of compressor 323 (e.g., LT compressor). This raised pressure of second evaporator 319 (e.g., raised LT evaporator pressure) may reduce the energy consumption of compressor 323 (e.g., LT compressor’s energy consumption) for a same amount of heat absorbed and this may further increase energy efficiency of fluid handling system 300D. [00151] A three-way valve may be after evaporator 318 (e.g., MT evaporator) to bypass at least a portion of the flow from evaporator 318 from going through heat exchanger 372 as needed and may facilitate control of the suction superheat of main compressor 322 (e.g., MT compressor suction superheat).

[00152] A three-way valve may be after second evaporator 319 (e.g., LT evaporator) to bypass at least a portion of the flow from second evaporator 319 from going through heat exchanger 374 as needed and may facilitate control of the suction superheat of compressor 323 (e.g., LT compressor suction superheat).

[00153] FIG. 3E is a schematic diagram of a fluid handling system 300E including a PX 310, according to some embodiments. In some embodiments, fluid handling system 300E is a boosterless subcooling PX architecture with LPin cooling using exit flow from evaporator 318 (e.g., MT evaporator exit flow).

[00154] Exit flow from main gas cooler 329 is split into two streams. The first stream goes to HPin of PX 310 after being subcooled in subcooler 315 (HX1). The second stream drops pressure through subcooling valve 312 (subcooling high pressure valve) and becomes cold two-phase liquid-gas mixture and then proceeds through subcooler 315 (HX1) to exchange heat with the first stream. Since the second stream has cold liquid (e.g., colder than the first stream), the second stream absorbs heat from the first stream and in so doing subcools the first stream. This allows HPin of PX 310 to be subcooled and reduce flash gas in LPout flow after expansion through PX 310.

[00155] Subcooled HPin flow then expands through PX 310 to a lower pressure and is ejected out of LPout port of the PX 310. This expansion fo the subcooled HPin flow produces more liquid mass fraction (e.g., lesser flash gas) in the LPout flow. The LPout flow then proceeds to the receiver 313 (e.g., flash tank). Since the flash gas in LPout does not contribute to any heat absorption in the fluid handling system 300E (e.g., refrigeration system) but still is to be compressed by compressor 322 (e.g., MT compressor), the reduction in the amount of flash caused by subcooling in subcooler 315 (HX1) increases the COP (e.g., system efficiency).

[00156] The second stream, after exchanging heat with the first stream in subcooler 315 (HX1), proceeds to LPin port of the PX 310 after passing through heat exchanger 376 (HX2). PX 310 compresses the second stream to high pressure and ejects the second stream out of the HPout port. HPout flow then rejects heat to the ambient in auxiliary gas cooler 327 and is cooled. The second stream then drops pressure across auxiliary valve 369 (e.g., auxiliary high-pressure valve) and becomes a much colder two-phase liquid-gas mixture and proceed to the receiver 313 (e.g., flash tank) where the second stream is merged with the LPout flow. [00157] Heat exchanger 376 (HX2) is used to cool LPin flow using a portion of exit flow from evaporator 318 (MT evaporator exit flow, which is much cooler than LPin flow). This reduces temperature of LPin flow and increases density of LPin flow and mass boost ratio of PX 310 (e.g., PX can compress more LPin mass flow per unit HPin mass flow). This provides flexibility to increase the mass flow going through subcooling valve 312 (e.g., subcooling high pressure valve) that is used for subcooling the HPin flow through the PX 310 and achieve a flow split (e.g., substantially optimal flow split) after main gas cooler 329 to increase efficiency of fluid handling system 300E.

[00158] A three-way valve after evaporator 318 (e.g., MT evaporator) may be controlled based on how much flow from evaporator 318 (e.g., MT evaporator) is used to cool the LPin flow and heat the exit flow of evaporator 318 (e.g., MT evaporator exit flow) before proceeding to the inlet of compressor 322 (e.g., MT compressor suction).

[00159] Heat exchanger 376 (HX2) provides superheated fluid to the exit flow of evaporator 318 (e.g., MT evaporator exit flow) and may allow increasing pressure of evaporator 318 (e.g., MT evaporator pressure) while still meeting a suction superheat requirement of main compressor 322 (e.g., MT compressor suction superheat requirement). This raised pressure of evaporator 318 (e.g., raised MT evaporator pressure) may reduce the power consumption of main compressor 322 (e.g., MT compressor power consumption) for a given amount of heat absorbed in the evaporator 318 which may further increase efficiency of fluid handling system 300E.

[00160] FIG. 3F is a schematic diagram of a fluid handling system 300F including a PX 310, according to some embodiments. Fluid handling system 3 OOF may be a boosterless subcooling PX architecture that has LPin cooling and LPout heat exchange. The architecture of fluid handling system 3 OOF may be similar to the architecture of fluid handling system 300E except for one or more of the following. [00161] Heat exchanger 379 (HX3) may be used to increase the liquid mass fraction of the LPout flow using at least a portion of exit flow of the second evaporator 319 (e.g., LT evaporator exit flow, which may be much cooler than LPout flow). This reduces the amount of flash gas in LPout flow and since the flash gas is to be compressed by the main compressor

322 (e.g., MT compressor), the reduced flash gas reduces the energy consumption of main compressor 322 (e.g., MT compressor) and this may increase the energy efficiency of the fluid handling system 300F.

[00162] A three-way valve may be disposed after second evaporator 319 (e.g., LT evaporator) and may be controlled based on how much flow from second evaporator 319 is used to exchange heat with the LPout flow and heat the exit fluid flow of the second evaporator 319 (e.g., LT evaporator exit flow) before proceeding to the inlet of compressor

323 (e.g., LT compressor suction).

[00163] Heat exchanger 379 (HX3) may provide superheated fluid to the exit flow of second evaporator 319 (e.g., LT evaporator exit flow) which may allow increasing pressure of the second evaporator 319 (e.g., LT evaporator pressure) while still meeting suction superheat requirement of compressor 323 (e.g., LT compressor suction superheat requirement). This raised pressure of second evaporator 319 (e.g., raised LT evaporator pressure) may reduce power consumption of second compressor 323 (e.g., LT compressor power consumption) for a given amount of heat absorbed in the second evaporator 319 (e.g., LT evaporator) which further increases system efficiency of fluid handling system 300F.

[00164] FIG. 3G is a schematic diagram of a fluid handling system 300G including a PX 310, according to some embodiments. Fluid handling system 300G may be a boosterless subcooling PX architecture that has LPout heat exchange and main high pressure valve bypass (e.g., valve X). The architecture of fluid handling system 300G may be similar to the architecture of fluid handling system 3 OOF except for one or more of the following.

[00165] Flow split 380 (e.g., first flow split, three-way valve) may bypass at least a portion of the flow from the exit of the main gas cooler 329 to send through valve 384 (e.g., main high-pressure valve). Valve 384 may drop the pressure of this flow and convert the flow into a cold two-phase liquid gas mixture. This low-pressure cold two-phase flow may then continue to the receiver 313 (e.g., flash tank).

[00166] Substantially all of the flow may be bypassed and sent through valve 384 if PX 310 is to be stopped. This allows continuous successful operation of the fluid handling system 300G even if the PX 310 is taken offline (e.g., for servicing, etc.). Any of the architectures described herein may include functionality such as that depicted in FIG. 3G for bypassing a PX, servicing the PX, taking the PX offline, or the like.

[00167] A portion of the flow is bypassed through flow split 380 if the exit flow of main gas cooler 329 is more than what the PX 310 can handle. In such a scenario, an amount (e.g., substantially optional amount) of flow is directed through HPin of PX 310 and the rest of the flow proceeds through valve 384. For example, flow may be provided to PX 310 until a maximum operational speed of PX 310 is achieved, and additional flow (e.g., as required to maintain a target main gas cooler 329 pressure) may bypass PX 310.

[00168] A pressure setpoint for valve 384 may be set higher (e.g., a little higher) than pressure setpoint of HPin of PX 310 so that valve 384 only opens when maximum flow capacity of PX 310 is reached.

[00169] Flow split 382 may be controlled to control flow through subcooler 315 and subcooling valve 312.

[00170] Heat exchanger 378 may be used to cool fluid flowing from subcooler 315 before providing the fluid to a low-pressure inlet of PX 310. Fluid flow output by evaporator 318 (e.g., cooler fluid flow) may be utilized in Heat exchanger 378 to cool fluid flowing between a secondary outlet (e.g., cooling outlet) of subcooler 315 and a low-pressure inlet of PX 310. Cooling of fluid provided to the low-pressure inlet of PX 310 may increase a density of the fluid, increase a mass boost ratio, increase a mass flow that can be compressed by the PX, etc., which may raise efficiency of the fluid handling system 300G. Heat exchanger 378 may also enable increased pressure of operation of evaporator 318, and suction pressure of main compressor 322, while maintained a target suction superheat for the main compressor 322. Increasing evaporator 318 pressure may reduce energy consumption of main compressor 322 and increase system efficiency further.

[00171] FIG. 4A is a schematic diagram of a fluid handling system 400A including PX 410, subcooler 415, and various controllers and other components for providing control of fluid handling system 400A, according to some embodiments.

[00172] Fluid handling system 400A includes components for performing heat transfer operations. Fluid handling system 400A includes PX 410, main gas cooler 429, auxiliary gas cooler 427, and evaporator 418. Fluid handling system 400 A further includes subcooler 415 and subcooling valve 412. Fluid handling system 400A further includes receiver 413, flash gas valve 420, and expansion valve 416. Fluid handling system 400A further includes auxiliary valve 469, main compressor 422, and auxiliary cooling component 428. Components of fluid handling system 400A may share one or more features with corresponding components of fluid handling system 300 A of FIG. 3 A.

[00173] Fluid handling system 400A may include one or more sensors. The one or more sensors measure property values associated with the system. For example, one or more temperature sensors may measure temperature of a flowing fluid, of the environment, of hot and/or cold sinks associated with the system, etc. One or more pressure gauges may measure pressure of a fluid of fluid handling system 400A. One or more flow meters may measure flow (e.g., mass flow) of fluid through fluid handling system 400A. One or more density meters (e.g., two phase fluid density meters, two phase density meters, Coriolis flow meters, etc.) may measure density of a fluid of fluid handling system 400A. Other sensors (e.g., meters) may measure additional property values, e.g., work performed by various components, heat flow through the system, power consumed by components of the system, total fluid flow through various portions of the system, etc. Depicted in FIG. 4A are gauge 480, gauge 481, gauge 482, and gauge 483. In some embodiments, a depiction of a gauge may indicate the inclusion of multiple instruments, e.g., a gauge to determine volumetric flow may include a device for measuring mass flow and a device for measuring density of a fluid. In some cases, one or more sensors may not be depicted for visual clarity of FIGS. 4A-B.

[00174] Fluid handling system 400A includes controllers 490, 491, 492, 493, 494 and 495. Controllers of fluid handling system 400A may be PID controllers. Controllers of fluid handling system 400A may perform operations based on a known relationship between sensor data and control output, e.g., via a lookup table, functional form of the relationship, or the like.

[00175] Control of fluid handling system 400A may be performed by computing devices, e.g., general purpose computing devices (desktop computers, laptop computers, tablets, smart phones, etc.) executing instructions to perform control tasks. Control of fluid handling system 400A may be performed by purpose-built computing devices. Control of fluid handling system 400A may be performed by control devices such as PID controllers, microcontrollers, or other known methods for providing control signals. Control of fluid handling system 400A may include devices performing multiple operations, such as a single device executing operations of controller 490 and controller 491, a single device executing operations of controller 491, controller 492, and controller 495, a single device executing operations of all controllers of fluid handling system 400A, or any permutation of functions of various controllers being performed by combinations of computing devices. [00176] Controller 490 is operatively coupled to PX 410. Controller 490 may receive one or more measurements from gauge 480. Controller 490 may receive pressure measurements of fluid from gauge 480. Controller 490 may receive measurements as raw measurement data, as preprocessed measurement data, as averaged (e.g., boxcar averaged) measurement data, or the like. In some embodiments, controller 490 may receive additional measurement data, e.g., from one or more other sensors associated with fluid handling system 400A. Controller 490 may receive ambient temperature data, e.g., of the environment in the vicinity of main gas cooler 429 and/or auxiliary gas cooler 427 (for instance, in the case of a refrigeration system) or the environment in the vicinity of evaporator 418 (for instance, in the case of a heat pump system). Controller 490 may receive sensor data from PX 410, e.g., data indicative of a speed of operation of PX 410, etc. Controller 490 may be configured to generate one or more control signals based on received measurement data. Controller 490 may provide control signals to a device configured to adjust a speed of operation of PX 410, such as a motor coupled to PX 410 (e.g., coupled to a rotor of PX 410).

[00177] Controller 493 is operatively coupled to auxiliary cooling component 428. Auxiliary cooling component 428 may be a device configured to increase heat transfer between auxiliary gas cooler 427 and the surrounding environment. For example, auxiliary gas cooler 427 may reject heat to the ambient atmosphere, and cooling component 428 may be a fan that increases transfer of heat from auxiliary gas cooler 427 to the atmosphere. Auxiliary cooling component 428 may be a heat exchanger coupled to auxiliary gas cooler 427 or another type of component that increases heat transfer away from auxiliary gas cooler 427.

[00178] In some embodiments, controller 493 may receive a data measurement from gauge 482. Gauge 482 may provide a temperature measurement of a fluid temperature of auxiliary gas cooler 427. Gauge 482 may provide a temperature measurement of a fluid temperature of fluid output from auxiliary gas cooler 427. Controller 493 may generate a control signal based on data provided by gauge 482. Controller 493 may generate a control signal to achieve a target temperature of a fluid output by the auxiliary gas cooler 427. Controller 493 may generate a control signal to adjust operation of auxiliary cooling component 428. For example, controller 493 may adjust a speed of operation of a fan to achieve a target temperature (e.g., within a threshold) of fluid at the outlet of auxiliary gas cooler 427.

[00179] In some embodiments, a target fluid temperature of fluid output by auxiliary gas cooler 427 may be based on a temperature of fluid output by main gas cooler 429. A target temperature of fluid output by main gas cooler 429 may be generated based on environmental conditions, including ambient temperature, target performance, efficiency, or heat transfer of fluid handling system 400A, or the like. In some embodiments, main gas cooler 429 and auxiliary gas cooler 427 may reject heat to the same environment (e.g., both gas coolers may be situated on the roof of a building, to reject heat to the environment). Controller 493 may receive indications of temperature of fluid output by main gas cooler 429 (e.g., via gauge 480) and generate a control signal based on maintaining a difference between temperature of fluid output by main gas cooler 429 and auxiliary gas cooler 427 within a target threshold. [00180] Controller 491 is operatively coupled to subcooling valve 412. Controller 491 may receive sensor data from gauge 481. Gauge 481 may indicate a temperature of fluid output by subcooler 415. Data generated by gauge 481 may be utilized to determine subcooling performing by subcooler 415 (e.g., further cooling beyond cooling to phase transition the fluid to a liquid, which may be performed by main gas cooler 429). Data indicative of temperature before subcooler 415 (e.g., generated by gauge 480) may be utilized in determining subcooling of the fluid performed by subcooler 415. Controller 491 may provide one or more control signals to subcooling valve 412. Controller 491 may provide a control signal to subcooling valve 412 based on temperature data. Controller 491 may provide one or more control signals to subcooling valve 412 based on a difference in temperature between fluid provided to a main inlet of subcooler 415 (e.g., from main gas cooler 429) and fluid provided by a main outlet of subcooler 415 (e.g., to a high-pressure inlet of PX 410). Controller 491 may generate and/or provide a control signal based on a difference in temperature measurement provided by gauge 481 and gauge 480, a difference between a temperature measurement provided by gauge 481 and a target fluid temperature of fluid output by main gas cooler 429 (e.g., based on ambient temperature), or the like.

[00181] Controller 492 is operatively coupled to auxiliary valve 469. Controller 492 may provide a control signal to auxiliary valve 469 based on an opening of subcooling valve 412, e.g., a signal indicative of an opening of subcooling valve 412 received from controller 491. In some embodiments, a signal may be provided from subcooling valve 412 indicative of an opening (e.g., a percent of maximum opening) of subcooling valve 412. In some embodiments, the control signal provided to subcooling valve 412 may be provided to controller 492, and/or provided directly to auxiliary valve 469. An opening of auxiliary valve 469 may be based on an opening of subcooling valve 412.

[00182] In some embodiments, controller 494 may be operatively coupled to subcooling valve 412. Controller 494 may receive data indicative of an opening of flash gas valve 420. In some embodiments, flash gas valve 420 may be operated by controls of a parent rack, e.g., an existing system to which PX 410 and associated equipment was added as a retrofit. Control of flash gas valve 420 may be difficult or impossible to adjust by the PX system. However, increased cooling of main fluid flow by subcooler 415 may reduce an amount of flash gas in receiver 413. Flash gas valve 420 may be operated based on gas content of receiver 413, pressure of receiver 413, or the like. By adjusting subcooling valve 412 based on flash gas valve 420 opening, fluid handling system 400A may maintain a target level of cooling of main fluid passing through subcooler 415. In some embodiments, control of subcooling valve 412 may include multiple inputs, e.g., may include input based on flash gas valve 420 and gauge 481. In some embodiments, a minimum opening of flash gas valve 420 may be maintained, and control of subcooling valve 412 may revert to control based on flash gas valve 420 in situations where the minimum opening is approached (e.g., within a threshold). [00183] Controller 495 is communicatively coupled to subcooling valve 412. Controller 495 obtains information from gauge 483 indicative of a low-pressure inlet travel distance of PX 410, and generates and/or provides a control signal to subcooling valve 412 based on the low- pressure inlet travel distance. Travel distance may be or include a measure of flow through the PX 410 as compared to operating volume (e.g., duct volume, duct volume modified by operating speed, etc.) of the 4X 310. Travel distance may describe a portion of the operating volume of the PX 410 that is filled or displaced by an incoming fluid or an outgoing fluid. A value or range of travel distance may be targeted, e.g., the optimized efficiency of system 400A, optimizes heat transfer, or the like. In some embodiments, a target low-pressure inlet travel distance may be around 100%, 90%-110%, 80%-120%, 70%-130%, or any included or other range. Gauge 483 may include instrumentation for determining a low-pressure inlet travel distance of PX 410. Gauge 483 may include a mass flow meter. Gauge 483 may include a pressure gauge. Gauge 483 may include a temperature gauge. Controller 495 may further obtain an indication of a speed of operation of PX 410, e.g., to determine a duct volume of PX 410 available for fluid per unit time period, for determining travel distances associated with PX 410. In some embodiments, auxiliary valve 469 may also be controlled based on a travel distance, e.g., high-pressure outlet travel distance of PX 410. A high- pressure outlet travel distance may also be determine by a gauge (not shown), which may include instrumentation for determining high-pressure outlet fluid mass flow rate, high- pressure outlet fluid density, etc. Controller 495 may be utilized in combination with controller 494, in combination with controller 491, or in combination with controllers 494 and 491. In some embodiments, operations of controllers 491, 494, and 495 may be utilized based on conditions, e.g., different control operations based on different sensor inputs may be utilized for control of subcooling valve 412 under different conditions. In some embodiments, a combination of operations of controllers 491, 494, and/or 495 may be utilized in generating and/or providing a control signal to subcooling valve 412. For example, a lookup table may include values for an opening of subcooling valve 412 based on inputs including measurements of gauge 481, flash gas valve 420, and/or gauge 483.

[00184] A fluid handling system (e.g., refrigeration system) may include devices for performing operations of any combination of the above-described controllers. A fluid handling system may include devices performing operations of controller 490. A fluid handling system may include devices performing operations of controller 491. A fluid handling system may include devices performing operations of controller 492. A fluid handling system may include devices performing operations of controller 493. A fluid handling system may include devices performing operations of controller 494. A fluid handling system may include devices performing operations of controller 495. A fluid handling system may include sensors gauges, or other instrumentation in connection with any of the controllers described herein. A fluid handling system may include devices performing operations of any two of these controllers (e.g., controllers 490 and 491, controllers 490 and 494, controller 492 and 495, etc.), any three of these controllers, etc. Any combination of these controllers may be included in a fluid handling system (e.g., refrigeration system).

[00185] In some embodiments, a controller (e.g., a central controller, a system controller, which may be combined with one or more of controllers 490 through 495) receives sensor data indicative of a temperature of a refrigerated space (e.g., the cold reservoir proximate evaporator 418) and/or a temperature of a heated space (e.g., the hot reservoir proximate main gas cooler 429). The controller may control subcooling valve 412, auxiliary valve 369, auxiliary cooling component 428, etc., based on sensor data received from one or more sensors of the fluid handling system 400A (e.g., one or more fluid flowrate sensors, temperature sensors, pressure sensors, etc.). In some embodiments, one or more sensors (e.g., pressure sensors, flow sensors, temperature sensors, etc.) are disposed proximate inlets and/or outlets of the various components of the fluid handling system 400A (e.g., fluids discharged from various components). In some embodiments, one or more sensors are disposed internal to the components of the fluid handling system 400A. In some embodiments, a pressure sensor may be disposed proximate the inlet of the main compressor 422 and an additional pressure sensor may be disposed proximate the outlet of the main compressor 422. In some embodiments, a temperature sensor may be disposed proximate the inlet of the evaporator 418 and another temperature sensor may be disposed proximate the outlet of the evaporator 418 (e.g., for measuring temperature of fluid discharged from evaporator 18). In some embodiments, a temperature sensor may be disposed internal to the main gas cooler 3429 and/or auxiliary gas cooler 427. In some embodiments, a flow sensor may be located at each of the inlets and outlets of the PX 410 to measure a flow of the first fluid and the second fluid into and out of the PX 410.

[00186] In some embodiments, a controller (e.g., a central controller, a system controller, which may be combined with one or more of controllers 490 through 495, and/or additional controllers 496-499 of FIG. 4B) receives sensor data indicative of a temperature of a refrigerated space (e.g., a cold reservoir proximate evaporator 418) and/or a temperature of a heated space (e.g., a hot reservoir proximate main gas cooler 429). The controller may control auxiliary cooling component 428, auxiliary valve 469, PX 410, main compressor 422, subcooling valve 412, or any other controllable components of a fluid handling system based on sensor data received from one or more sensors of the fluid handling system (e.g., one or more fluid flowrate sensors, temperature sensors, pressure sensors, etc.). In some embodiments, one or more sensors (e.g., pressure sensors, flow sensors, temperature sensors, etc.) are disposed proximate inlets and/or outlets of the various components of the fluid handling system 400A (e.g., fluids discharged from various components). In some embodiments, one or more sensors are disposed internal to the components of the fluid handling system 400A. In some embodiments, a pressure sensor may be disposed proximate the inlet of the main compressor 422 and an additional pressure sensor may be disposed proximate the outlet of the main compressor 422. In some embodiments, a temperature sensor may be disposed proximate the inlet of the evaporator 418 and another temperature sensor may be disposed proximate the outlet of the evaporator 418 (e.g., for measuring temperature of fluid discharged from evaporator 418). In some embodiments, a temperature sensor may be disposed internal to the main gas cooler 429 and/or auxiliary gas cooler 427. In some embodiments, a flow sensor may be located at each of the inlets and outlets of the PX 410 to measure a flow of the first fluid and the second fluid into and out of the PX 410.

[00187] FIG. 4B is a schematic diagram of a fluid handling system 400B including sensors and controllers, according to some embodiments. Fluid handling system 400B includes similar components to fluid handling system 300B of FIG. 3B. Components of fluid handling system 400B may share one or more features, functions, or properties of corresponding components of fluid handling system 300B. Fluid handling system 400B includes a number of sensors, e.g., gauge 480, gauge 483, gauge 484, etc. Sensors may share one or more features, functions, or properties with sensors included in fluid handling system 400 A of FIG. 4A. Fluid handling system 400B includes a number of controllers, such as controller 490, controller 496, controller 497, controller 498, and controller 499. Controllers may include or share features and/or properties with controllers included in fluid handling system 400B, such as architecture of the controllers, potential grouping of controller functions by a smaller number of computing devices, or the like. Some controllers may be applicable to various types of architectures, and controllers may be used together in any combination relevant for a target fluid handling system architecture. For example, an architecture such as fluid handling system 400B may benefit from a controller directed toward an auxiliary cooling component, such as controller 492 of FIG 4A. Any number of controllers described herein may be included in a target architecture and may be executed by any number of devices.

[00188] Fluid handling system 400B includes main gas cooler 429, PX 410, associated motor 408, bypass high-pressure valve 448, first low-pressure control valve 450, second low- pressure control valve 452, auxiliary gas cooler 427, auxiliary receiver 411, receiver 413, flash gas valve 420, expansion valve 416, second expansion valve 417, evaporator 418, second evaporator 419, low-temperature compressor 423, and main compressor 422. These components may perform similar functions to corresponding components of fluid handling system 300B.

[00189] Fluid handling system 400B includes gauge 480, gauge 483, and gauge 484. The gauges may include similar characteristics to gauges of fluid handling system 400A. Each gauge of fluid handling system may include a number of sensors, meters, or other instruments for determining measurements related to control of fluid handling system 400B. A gauge may include one or more temperature sensors, pressure sensors, flow meters, density meters, or the like.

[00190] Fluid handling system 400B includes controller 490. Controller 490 may be used to provide control signals for adjusting a speed of operation of PX 410 (e.g., via motor 408). Controller 490 may adjust a speed of operation of PX 410 to maintain a target pressure of fluid of main gas cooler 429, e.g., provided by gauge 480, provided by a gauge internal to main gas cooler 429, or the like.

[00191] Fluid handling system 400B includes controller 496. Controller 496 is operatively coupled to bypass high-pressure valve 448. Bypass high-pressure valve 448 may provide a portion of fluid output by main gas cooler 429 to auxiliary receiver 411. An opening (e.g., a percentage of a maximum opening) of bypass high-pressure valve 448 may be utilized in determining a portion of fluid output by main gas cooler 429 that is provided to auxiliary receiver 411, and a portion that is provided to a high-pressure inlet of PX 410. Controller 496 may generate a control signal based on measurements of one or more sensors (not shown) measuring conditions of the auxiliary receiver 411. Controller 496 may generate a control signal based on pressure of auxiliary receiver 411, e.g., fluid pressure of auxiliary receiver 411. Controller 496 may generate a control signal to adjust flow of fluid to auxiliary receiver 411 until a target pressure condition is achieved (e.g., within a threshold).

[00192] Fluid handling system 400B includes controller 497. Controller 497 is operatively coupled to auxiliary valve 469. Controller 497 may generate a control signal based on measurement data received from gauge 484. Gauge 484 may be configured to generate an indication of a high-pressure outlet travel distance of PX 410. Determining a high-pressure outlet travel distance may include performing a calculation based on high-pressure outlet mass flow rate, high-pressure outlet density, and/or PX 410 operating speed (e.g., rotational speed, working volume, or the like). Auxiliary valve 469 may be adjusted until a target high- pressure outlet travel distance is achieved (e.g., within a threshold).

[00193] Fluid handling system 400B includes controller 498. Controller 498 is operatively coupled to second low-pressure control valve 452. Second low-pressure control valve 452 determines fluid flow from auxiliary receiver 411 to a low-pressure inlet of PX 410. Controller 498 may generate a control signal based on one or more signals received from gauge 483. Gauge 483 may determine a low-pressure inlet travel distance of PX 410. A low- pressure inlet travel distance may be determined based on a few different criteria, a combination of criteria, an averaging or other statistical metric of values determined from various methods, or the like. In some embodiments, a low-pressure inlet travel distance of PX 410 may be determined or estimated based on valve characteristics of second low-pressure control valve 452. For example, mass flow through second low-pressure control valve 452 may be estimated based on characteristics of the valve (e.g., vendor characteristics) as well as fluid conditions (e.g., pressure and temperature at the valve inlet). In some embodiments, a low-pressure inlet travel distance may be targeted, and a volumetric flow through second low-pressure valve 452 may be generated to achieve the target travel distance (e.g., as a function of PX 410 operational speed). In some embodiments, an opening of second low- pressure valve 452 may be determined as a function (e.g., via a look-up table, via a mathematical function, or the like) of PX 410 operational speed. In some embodiments, gauge 483 may provide indications of travel distance, e.g., mass flow, fluid pressure, fluid temperature, etc., which may be utilized by controller 498 to generate a control signal for second low-pressure control valve 452.

[00194] Fluid handling system 400B includes controller 499. Controller 499 is operatively coupled to first low-pressure control valve 450. Controller 499 may receive data from one or more sensors of auxiliary receiver 411 for generating a control signal. Controller 499 may obtain an indication of liquid level of a mixed fluid (e.g., including gas and liquid components) in auxiliary receiver 411. First low-pressure control valve 450 may be provided control signals to maintain a target range of fluid level within auxiliary receiver 411. First low-pressure control valve 450 may be opened in response to an increase of liquid level in auxiliary receiver 411. First low-pressure control valve 450 may be caused to close when liquid levels in auxiliary receiver 411 drops below a target level.

[00195] FIGS. 5A-E are flow diagrams illustrating methods 500A-E for controlling fluid handling systems (e.g., one or more of fluid handling systems 300A-B of FIGS. 3A-B), according to some embodiments. In some embodiments, methods 500A-E are performed by processing logic that includes hardware (e.g., circuitry, dedicated logic, programmable logic, microcode, processing device, etc.), software (such as instructions run on a processing device, run on a processor such as a central processing unit or graphics processing unit, a general purpose computer system, or a dedicated machine), firmware, microcode, or a combination thereof. In some embodiments, methods 500A-E are performed, at least in part, by one or more controllers. In some embodiments, a non-transitory storage medium stores instructions that when executed by one or more processing, cause the processing device to perform methods 500A-E.

[00196] For simplicity of explanation, methods 500A-E are depicted and described as a series of operations. However, operations in accordance with this disclosure can occur in various orders and/or concurrently and with other operations not presented and described herein. Furthermore, in some embodiments, not all illustrated operations are performed to implement methods 500A-E in accordance with the disclosed subject matter. In addition, those skilled in the art will understand and appreciate that methods 500A-E are could alternatively be represented as a series of interrelated states via a state diagram or events. [00197] FIG. 5A is a flow diagram of a method 500A for providing control of a fluid handling system, according to some embodiments. At block 502, processing logic (e.g., a processing device, a controller, a computer processor, etc.) obtains first temperature data indicative of subcooling of a first fluid in a heat exchanger. The subcooling may be a difference in temperature between fluid provided to the heat exchanger and fluid provided by the heat exchanger. The first fluid may flow through a first fluid channel of the heat exchanger. The first fluid channel may be a main channel, a primary channel, or the like. Fluid of the first channel may be configured to exchange heat with fluid of a second channel, cooling channel, cooling fluid channel, or the like. Fluid of the first channel may lose heat to a cooler secondary fluid in the secondary channel. The first fluid may be provided to the heat exchanger from a first gas cooler, such as a main gas cooler. The first fluid may be provided from the heat exchanger to a PX. The first fluid may be provided to a high-pressure inlet of the PX.

[00198] At block 504, processing logic optionally obtains opening data of a second control valve. The second control valve is coupled between an outlet of a receiver and an inlet of a compressor. The second control valve may be a flash gas valve, e.g., the second control valve may enable removal of gas from a gas/liquid mixture contained in the receiver. The second control valve may be opened based on conditions of the receiver. The opening data may be received from the second control valve, from a sensor associated with the second control valve, from a controller associated with the second control valve, or the like.

[00199] At block 506, processing logic optionally obtains an indication of a first travel distance associated with a low-pressure inlet of the PX. The first travel distance may be determined based on sensors proximate the low-pressure inlet of the PX. The first travel distance may be determined based on measured properties of fluid provided to the low- pressure inlet of the PX. The first travel distance may be determined based on mass flow rate, fluid temperature, fluid pressure, or the like.

[00200] At block 508, processing logic generates a first control signal. Generation of the control signal may optionally include operations of blocks 510 and 512. The first control signal is based on at least the first temperature data. The first control data may further be based on the opening data and the first travel distance. Generating the first control signal optionally includes determining that subcooling of the first fluid does not satisfy a target threshold condition, such as subcooling of a target temperature drop across the heat exchanger. Generating the first control signal optionally includes obtaining second temperature data indicative of temperature of fluid output by the first gas cooler. Generating the first control signal optionally includes determining a target subcooling threshold, e.g., a target subcooling temperature change may be based on the temperature of fluid output by the first gas cooler, may be based on ambient temperature, or the like.

[00201] At block 510, generating the first control signal optionally includes determining whether the opening data is within a threshold of a minimum target opening of the second control valve. For example, the first control signal may ensure that the second control valve does not close beyond the minimum target opening.

[00202] At block 512, generating the first control signal optionally includes determining a target opening of the first control valve. The target opening of the first control valve may be chosen to maintain at least the minimum target opening of the second control valve. In some embodiments, increasing subcooling performed by the heat exchanger may decrease flash gas in the receiver. Subcooling may be maintained such that enough flash gas is included in the receiver to maintain at least a minimum opening of the second control valve.

[00203] At block 514, processing logic provides the first control signal to a first control valve. The first control valve is coupled between an outlet of the first gas cooler (e.g., a main gas cooler) and an inlet of a second fluid channel (e.g., a cooling channel) of the heat exchanger. The first control valve may be configured to adjust an opening of the first control valve based on the first control signal. The opening of the first control valve may determine a portion of fluid output from the first gas cooler provided to the first fluid channel of the heat exchanger.

[00204] At block 516, processing logic optionally obtains an indication of a second travel distance associated with a high-pressure outlet of the PX. Processing logic further optionally generates a second control signal based on the second travel distance. Processing logic further provides the second control signal to a third control valve, wherein the third control valve is coupled to receive a second fluid from the PX and provide the second fluid to the receiver. The third control valve is configured to adjust an opening of the third control valve based on the second control signal.

[00205] FIG. 5B is a flow diagram of a method 500B for providing control of a refrigeration system, according to some embodiments. At block 518, processing logic obtains an indication of a fluid level of an auxiliary receiver of a refrigeration system. The refrigeration includes a pressure exchanger. The pressure exchanger is configured to receive a first fluid from a first gas cooler, to receive a second fluid from the auxiliary receiver, and exchange pressure between the first fluid and the second fluid. The refrigeration system may further include a main receiver, which may be fluidly coupled to the auxiliary receiver.

[00206] At block 520, processing logic generates a first control signal based on the fluid level of the auxiliary receiver. In some embodiments, the fluid level may exceed a threshold level. In some embodiments, the fluid level may be less than a threshold level. In some embodiments, there may be multiple thresholds, e.g., there may be a range of liquid levels that do not cause control signals for adjusting liquid level to be generated.

[00207] At block 522, processing logic provides the first control signal to a first control valve. The first control valve is configured to determine flow of fluid from the auxiliary receiver to a main receiver based on the first control signal. For example, a mass flow, volume flow, flow speed, or the like may be determined by an opening of the first control valve (e.g., a percent of a maximum opening).

[00208] At block 524, processing logic optionally obtains an indication of fluid pressure of the first gas cooler. Processing logic further optionally generates a second control signal based on the fluid pressure of the first gas cooler. Processing logic further provides the second control signal to a motor of the PX. The motor of the PX may be configured to adjust a speed of operation of the PX based on the second control signal.

[00209] At block 526, processing logic optionally obtains an indication of a pressure differential between the auxiliary receiver and the main receiver. Processing logic further optionally generates a third control signal based on the pressure differential between the auxiliary receiver and the main receiver. Processing logic further optionally provides the third control signal to a second control valve. The second control valve is coupled to provide first fluid from the first gas cooler to the auxiliary receiver, and the second control valve is configured to maintain a target pressure differential between the auxiliary receiver and the main receiver.

[00210] At block 528, processing logic optionally obtains an indication of a travel distance of the second fluid associated with a high-pressure outlet of the PX. The indication of the travel distance may be based on a measured mass flow of the second fluid and a measured density of the second fluid. Processing logic further optionally generates a fourth control signal based on the travel distance of the second fluid associated with the high-pressure outlet. Processing logic further optionally provides the fourth control signal to a third control valve, wherein the third control valve is coupled to determine fluid flow of the second fluid from the high-pressure outlet of the PX through a second gas cooler to the auxiliary receiver based on an opening of the third control valve. The third control valve may be configured to adjust the opening of the third control valve based on the fourth control signal.

[00211] At block 530, processing logic optionally obtains an indication of fluid temperature at an outlet of the second gas cooler. Processing logic may further optionally generate a fifth control signal based on the fluid temperature. Processing logic may further optionally provide the fifth control signal to a device for adjusting heat transfer from the second gas cooler, such as a fan to increase heat transfer from the second gas cooler to an environment proximate the second gas cooler.

[00212] FIG. 5C is a flow diagram of a method 500C for providing control of a refrigeration system, according to some embodiments. Operations associated with blocks 532, 534, and 536 may share one or more features with operations of blocks 518, 520, and 522 of FIG. 5B. [00213] At block 532, processing logic obtains an indication of a fluid level of an auxiliary receiver of a refrigeration system. The refrigeration includes a pressure exchanger. The pressure exchanger is configured to receive a first fluid from a first gas cooler, to receive a second fluid from the auxiliary receiver, and exchange pressure between the first fluid and the second fluid.

[00214] At block 534, processing logic generates a first control signal based on the fluid level of the auxiliary receiver. In some embodiments, the fluid level may exceed a threshold level. In some embodiments, the fluid level may be less than a threshold level. In some embodiments, there may be multiple thresholds, e.g., there may be a range of liquid levels that do not cause control signals for adjusting liquid level to be generated.

[00215] At block 536, processing logic provides the first control signal to a first control valve. The first control valve is configured to determine flow of fluid from the auxiliary receiver to a main receiver based on the first control signal. For example, a mass flow, volume flow, flow speed, or the like may be determined by an opening of the first control valve (e.g., a percent of a maximum opening).

[00216] At block 538, processing logic optionally obtains an indication of a travel distance of the second fluid associated with a low-pressure inlet of the PX. The indication of the travel distance of the second fluid associated with the low-pressure inlet of the PX may be based on characteristics of the fluid provided to the low-pressure inlet of the PX (e.g., temperature, pressure, mass flow, etc.). The indication of the travel distance of the second fluid associated with (e.g., provided to) the low-pressure inlet of the PX may include accounting for valve characteristics of one or more valves of the refrigeration system. The indication of the travel distance of the second fluid associated with the low-pressure inlet of the PX may include accounting for an operating speed (e.g., rotational speed) of the PX.

[00217] At block 540, processing logic optionally generates a sixth control signal based on the travel distance of the second fluid associated with the low-pressure inlet. The sixth control signal may be utilized to achieve and/or maintain a target travel distance associated with the low-pressure inlet of the PX.

[00218] At block 542, processing logic optionally provides the sixth control signal to a fourth control valve. The fourth control valve may be coupled to determine fluid flow of the second fluid from the auxiliary receiver to the low-pressure inlet of the PX. The fourth control valve may adjust an opening of the fourth control valve based on the sixth control signal. [00219] FIG. 5D is a flow diagram of a method 500D for providing control of a refrigeration system, according to some embodiments. At block 544, processing logic obtains an indication of a pressure differential between a main receiver and an auxiliary receiver of the refrigeration system. The refrigeration system may include a PX, the two receivers, one or more gas coolers, one or more evaporators, and one or more compressors. The auxiliary receiver and the PX are configured to receive a first fluid from a first gas cooler. The auxiliary receiver is configured to provide a second fluid to the PX. The PX is configured to exchange pressure between the first fluid and the second fluid. The main receiver is configured to receive the first fluid from the PX.

[00220] At block 546, processing logic generates a first control signal based on the pressure differential. A first sensor may generate pressure data of the main receiver, and as second sensor may generate pressure data of the auxiliary receiver. A pressure differential may be based on data of the first sensor and data of the second sensor.

[00221] At block 548, processing logic provides the first control signal to a first control valve coupled between the first gas cooler and the auxiliary receiver. The first control valve is configured to adjust an opening of the first control valve based on the first control signal. An opening of the first control valve may determine a portion of fluid provided to the auxiliary receiver, and a portion of fluid provided to the PX.

[00222] At block 550, processing logic optionally obtains an indication of a fluid level of the auxiliary receiver. Processing logic further optionally generates a second control signal based on the fluid level of the auxiliary receiver. Processing logic further optionally provides the second control signal to a second control valve. The second control valve is coupled between the auxiliary receiver and the main receiver, e.g., fluid may be provided from the auxiliary receiver (maintained at a higher pressure) to the main receiver (maintained at a lower pressure) via the second control valve. The second control valve is configured to adjust an opening of the second control valve based on the second control signal.

[00223] At block 552, processing logic optionally obtains an indication of fluid pressure of the first gas cooler. Processing logic further optionally generates a third control signal based on the fluid pressure of the first gas cooler. Processing logic further optionally provides the third control signal to a motor of the PX. The motor of the PX is configured to adjust a speed of operation of the PX based on the third control signal. In some embodiments, the motor may speed up operation of the PX. In some embodiments, the motor may oppose motion of the PX and slow down operation of the PX. In some embodiments, slowing the PX may be utilized to generate electricity via the motor. [00224] At block 554, processing logic optionally obtains an indication of a travel distance of the second fluid associated with a low-pressure inlet of the PX. The processing logic further optionally generates a fourth control signal based on the travel distance of the second fluid associated with the low-pressure inlet. Processing logic further optionally provides the fourth control signal to a third control valve. The third control valve is coupled to determine fluid flow of the second fluid from the auxiliary receiver to the low-pressure inlet. The third control valve adjusts an opening of the third control valve based on the fourth control signal. [00225] FIG. 5E is a flow diagram of a method 500E for providing control of a refrigeration system, according to some embodiments. Operations of blocks 556, 558, and 560 may share one or more features with operations of blocks 544, 546, and 548 of FIG. 5D. At block 556, processing logic obtains an indication of a pressure differential between a main receiver and an auxiliary receiver of the refrigeration system. The refrigeration system may include a PX, the two receivers, one or more gas coolers, one or more evaporators, and one or more compressors. The auxiliary receiver and the PX are configured to receive a first fluid from a first gas cooler. The auxiliary receiver is configured to provide a second fluid to the PX. The PX is configured to exchange pressure between the first fluid and the second fluid. The main receiver is configured to receive the first fluid from the PX.

[00226] At block 558, processing logic generates a first control signal based on the pressure differential. A first sensor may generate pressure data of the main receiver, and as second sensor may generate pressure data of the auxiliary receiver. A pressure differential may be based on data of the first sensor and data of the second sensor.

[00227] At block 560, processing logic provides the first control signal to a first control valve coupled between the first gas cooler and the auxiliary receiver. The first control valve is configured to adjust an opening of the first control valve based on the first control signal. An opening of the first control valve may determine a portion of fluid provided to the auxiliary receiver, and a portion of fluid provided to the PX.

[00228] At block 562, processing logic optionally obtains an indication of a travel distance of the second fluid associated with a high-pressure outlet of the PX. The indication of travel distance may include or be based on measured mass flow and/or measured density of the second fluid. Processing logic further optionally generates a fifth control signal based on the travel distance of the second fluid associated with the high-pressure outlet. Processing logic further optionally provides the fifth control signal to a fourth control valve. The fourth control valve is coupled to determine fluid flow of the second fluid from the high-pressure outlet of the PX through a second gas cooler to the auxiliary receiver based on an opening of the fourth control valve. The fourth control valve is configured to adjust an opening of the fourth control valve based on the firth control signal.

[00229] At block 564, processing logic optionally obtains an indication of fluid temperature at an outlet of the second gas cooler, e.g., an auxiliary gas cooler. Processing logic further optionally generates a sixth control signal based on the fluid temperature. Processing logic further optionally provides the sixth control signal to a device for adjusting heat transfer from the second gas cooler. The device for adjusting heat transfer may be one or more fans for increasing thermal transfer of heat from the second gas cooler to a proximate environment. [00230] FIG. 6 is a block diagram illustrating a computer system 600, according to some embodiments. In some embodiments, the computer system 600 is a client device. In some embodiments, the computer system 600 is a controller device (e.g., server, control module, central control system, controllers 490-499 of FIGS. 4A-B, etc.).

[00231] In some embodiments, computer system 600 is connected (e.g., via a network, such as a Local Area Network (LAN), an intranet, an extranet, or the Internet) to other computer systems. Computer system 600 operates in the capacity of a server or a client computer in a client-server environment, or as a peer computer in a peer-to-peer or distributed network environment. In some embodiments, computer system 600 is provided by a personal computer (PC), a tablet PC, a Set-Top Box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any device capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that device. Further, the term "computer" shall include any collection of computers that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methods described herein.

[00232] In some embodiments, the computer system 600 includes a processing device 602, a volatile memory 604 (e.g., Random Access Memory (RAM)), a non-volatile memory 606 (e.g., Read-Only Memory (ROM) or Electrically-Erasable Programmable ROM (EEPROM)), and/or a data storage device 616, which communicates with each other via a bus 608.

[00233] In some embodiments, processing device 602 is provided by one or more processors such as a general purpose processor (such as, for example, a Complex Instruction Set Computing (CISC) microprocessor, a Reduced Instruction Set Computing (RISC) microprocessor, a Very Long Instruction Word (VLIW) microprocessor, a microprocessor implementing other types of instruction sets, or a microprocessor implementing a combination of types of instruction sets) or a specialized processor (such as, for example, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP), a PID controller, or a network processor). In some embodiments, processing device 602 is provided by one or more of a single processor, multiple processors, a single processor having multiple processing cores, and/or the like. [00234] In some embodiments, computer system 600 further includes a network interface device 622 (e.g., coupled to network 674). In some embodiments, the computer system 600 includes one or more input/output (I/O) devices. In some embodiments, computer system 600 also includes a video display unit 610 (e.g., a liquid crystal display (LCD)), an alphanumeric input device 612 (e.g., a keyboard), a cursor control device 614 (e.g., a mouse), and/or a signal generation device 620. Computer system 600 may include signal input device 615, e.g., for receiving signals from other devices. For example, signal input device 615 may facilitate reception by computer system 600 of measurement data from sensors associated with a fluid handling system. Signal generation device 620 may be utilized to generate and/or send control signals for sending instructions to one or more components of a fluid handling system. Signal generation device 620 may send control signals to various high-pressure valves, booster pumps, cooling components, PX components, etc.

[00235] In some implementations, data storage device 616 (e.g., disk drive storage, fixed and/or removable storage devices, fixed disk drive, removable memory card, optical storage, network attached storage (NAS), and/or storage area-network (SAN)) includes a non- transitory computer-readable storage medium 624 on which stores instructions 626 encoding any one or more of the methods or functions described herein, and for implementing methods described herein. Control module 133 (e.g., including any of controllers 490-499 of FIGS. 4A-B) may be included in instructions 626.

[00236] In some embodiments, instructions 626 also reside, completely or partially, within volatile memory 604 and/or within processing device 602 during execution thereof by computer system 600, hence, volatile memory 604 and processing device 602 also constitute machine-readable storage media, in some embodiments.

[00237] While computer-readable storage medium 624 is shown in the illustrative examples as a single medium, the term "computer-readable storage medium" shall include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of executable instructions. The term "computer-readable storage medium" shall also include any tangible medium that is capable of storing or encoding a set of instructions for execution by a computer that cause the computer to perform any one or more of the methods described herein. The term "computer- readable storage medium" shall include, but not be limited to, solid-state memories, optical media, and magnetic media.

[00238] The methods, components, and features described herein may be implemented by discrete hardware components or may be integrated in the functionality of other hardware components such as ASICs, FPGAs, DSPs or similar devices. In addition, the methods, components, and features may be implemented by firmware modules or functional circuitry within hardware devices. Further, the methods, components, and features may be implemented in any combination of hardware devices and computer program components, or in computer programs.

[00239] Unless specifically stated otherwise or clear from context, terms such as “actuating,” “adjusting,” “causing,” “controlling,” “determining,” “identifying,” “providing,” “receiving,” “generating,” “obtaining,” or the like, refer to actions and processes performed or implemented by computer systems that manipulates and transforms data represented as physical (electronic) quantities within the computer system registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. Also, the terms "first," "second," "third," "fourth," etc. as used herein are meant as labels to distinguish among different elements and may not have an ordinal meaning according to their numerical designation.

[00240] Examples described herein also relate to an apparatus for performing the methods described herein. This apparatus may be specially constructed for performing the methods described herein, or it may include a general purpose computer system selectively programmed by a computer program stored in the computer system. Such a computer program may be stored in a computer-readable tangible storage medium.

[00241] The methods and illustrative examples described herein are not inherently related to any particular computer or other apparatus. Various general purpose systems may be used in accordance with the teachings described herein, or it may prove convenient to construct more specialized apparatus to perform methods described herein and/or each of their individual functions, routines, subroutines, or operations. Examples of the structure for a variety of these systems are set forth in the description above.

[00242] The preceding description sets forth numerous specific details, such as examples of specific systems, components, methods, and so forth, in order to provide a good understanding of several embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that at least some embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known components or methods are not described in detail or are presented in simple block diagram format in order to avoid unnecessarily obscuring the present disclosure. Thus, the specific details set forth are merely exemplary. Particular implementations may vary from these exemplary details and still be contemplated to be within the scope of the present disclosure. Descriptions of systems herein may include descriptions of one or more optional components. Components may be included in combinations not specifically discussed in this disclosure, and still be within the scope of this disclosure. For example, any of controllers 390-395 of FIGS. 3A-D, alone or in any combination, may be included in a fluid handling system that is within the scope of this disclosure.

[00243] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” When the term “about,” “substantially,” or “approximately” is used herein, this is intended to mean that the nominal value presented is precise within ±10%. Also, the terms "first," "second," "third," "fourth," etc. as used herein are meant as labels to distinguish among different elements and can not necessarily have an ordinal meaning according to their numerical designation.

[00244] The terms “over,” “under,” “between,” “disposed on,” “before,” “after,” and “on” as used herein refer to a relative position of one material layer or component with respect to other layers or components. For example, one layer disposed on, over, or under another layer may be directly in contact with the other layer or may have one or more intervening layers. Moreover, one layer disposed between two layers may be directly in contact with the two layers or may have one or more intervening layers. Similarly, unless explicitly stated otherwise, one feature disposed between two features may be in direct contact with the adjacent features or may have one or more intervening layers or components.

[00245] Although the operations of the methods herein are shown and described in a particular order, the order of the operations of each method may be altered so that certain operations may be performed in an inverse order or so that certain operation may be performed, at least in part, concurrently with other operations. In another embodiment, instructions or sub-operations of distinct operations may be in an intermittent and/or alternating manner. [00246] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which each claim is entitled.

Claims

CLAIMS What is claimed is:

1. A system comprising: a pressure exchanger (PX) configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid; a first gas cooler configured to provide working fluid to a first inlet of a heat exchanger and a second inlet of the heat exchanger, wherein the heat exchanger is configured to exchange heat between fluid provided via the first inlet and fluid provided via the second inlet, and wherein a first outlet of the heat exchanger corresponding to the first inlet provides the first fluid to the PX, and a second outlet of the heat exchanger corresponding to the second inlet provides the second fluid to the PX; a receiver configured to receive the first fluid and the second fluid from the PX; and a first compressor configured to provide the working fluid to the first gas cooler.

2. The system of claim 1, further comprising a first evaporator configured to receive the working fluid from the receiver and provide the working fluid to the first compressor.

3. The system of claim 2, further comprising a second evaporator configured to receive the working fluid from the receiver and provide the working fluid to the first compressor, wherein the first evaporator is configured to maintain a first temperature of an environment proximate the first evaporator, and wherein the second evaporator is configured to maintain a second temperature, different than the first temperature, of an environment proximate the second evaporator.

4. The system of claim 3, further comprising a second compressor, wherein working fluid is provided to the second compressor by the second evaporator, and wherein an outlet of the second compressor is coupled to working fluid output by the first evaporator.

5. The system of claim 2, further comprising an auxiliary gas cooler, wherein the auxiliary gas cooler is coupled to receive the second fluid from the PX and provide the second fluid to the receiver.

6. The system of claim 5, wherein the auxiliary gas cooler comprises a secondary inlet and secondary outlet of the first gas cooler.

7. The system of claim 5, further comprising an auxiliary control valve, coupled between the PX and the receiver to determine a flow rate of the second fluid.

8. The system of claim 1, further comprising a control valve coupled between an outlet of the first gas cooler and the second inlet of the heat exchanger, wherein an opening of the control valve determines a portion of working fluid provided to the first inlet of the heat exchanger.

9. A system, comprising: a pressure exchanger (PX) configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid; a first receiver, wherein the first receiver is configured to receive the first fluid from the PX; a first gas cooler; and an auxiliary receiver, wherein the first gas cooler is configured to provide the first fluid to the PX and to provide working fluid to the auxiliary receiver, wherein the auxiliary receiver is to provide the second fluid to the PX.

10. The system of claim 9, further comprising an auxiliary gas cooler, wherein the auxiliary gas cooler is configured to receive the second fluid from the PX, and provide the second fluid to the auxiliary receiver.

11. The system of claim 10, further comprising an auxiliary control valve coupled between an outlet of the PX associated with the second fluid and the auxiliary receiver.

12. The system of claim 9, further comprising: an evaporator, configured to receive working fluid from the first receiver; and a compressor, configured to receive the working fluid from the evaporator, and provide the working fluid to the first gas cooler.

13. The system of claim 9, further comprising a first low-pressure control valve, coupled to provide the second fluid to the PX from the auxiliary receiver.

14. The system of claim 9, further comprising a second low-pressure control valve, coupled to provide working fluid from the auxiliary receiver to the first receiver.

15. The system of claim 9, further comprising a heat exchanger, comprising a first fluid channel comprising a first inlet coupled to a first outlet, and a second fluid channel comprising a second inlet coupled to a second outlet, wherein the first fluid channel is coupled between the first gas cooler and the PX, and wherein the second fluid channel is coupled to provide the second fluid to the auxiliary receiver.

16. The system of claim 15, wherein the second fluid channel is coupled to receive working fluid from an auxiliary gas cooler, and wherein the heat exchanger is configured to exchange heat between fluid of the second fluid channel and fluid of the first fluid channel.

17. A method comprising: obtaining, by a processing device, first temperature data indicative of subcooling of a first fluid in a heat exchanger, wherein the first fluid flows through a first fluid channel of the heat exchanger, and wherein the first fluid is received by the heat exchanger from a first gas cooler, and provided from the heat exchanger to a pressure exchanger (PX); generating a first control signal based on at least the first temperature data; and providing the first control signal to a first control valve, wherein the first control valve is coupled between an outlet of the first gas cooler and an inlet of a second fluid channel of the heat exchanger, and wherein the first control valve is configured to adjust an opening of the first control valve based on the first control signal.

18. The method of claim 17, wherein the opening of the first control valve determines a portion of fluid output from the first gas cooler that is provided to the first fluid channel of the heat exchanger.

19. The method of claim 17, wherein generating the first control signal comprises determining that the subcooling of the first fluid does not satisfy a target threshold condition.

20. The method of claim 19, wherein the determining that the subcooling of the first fluid does not satisfy the target threshold condition comprises: obtaining second temperature data indicative of temperature of a fluid output by the first gas cooler; and determining a target subcooling threshold based on the temperature of the fluid output by the first gas cooler.

21. The method of claim 17, further comprising obtaining opening data of a second control valve, wherein the second control valve is coupled between an outlet of a receiver and an inlet of a compressor, and wherein the generating of the first control signal is further based on the opening data.

22. The method of claim 21, wherein the generating of the first control signal comprises: determining whether the opening data is within a threshold of a minimum target opening of the second control valve; and determining a target opening of the first control valve to maintain at least the minimum target opening of the second control valve.

23. The method of claim 17, further comprising obtaining an indication of a first travel distance associated with a low-pressure inlet of the PX, wherein the first control signal is further based on the first travel distance.

24. The method of claim 23, further comprising: obtaining an indication of a second travel distance associated with a high-pressure outlet of the PX; generating a second control signal based on the second travel distance; and providing the second control signal to a third control valve, wherein the third control valve is coupled to receive a second fluid from the PX and provide the second fluid to a receiver, and wherein the third control valve is configured to adjust an opening of the third control valve based on the second control signal.

25. A method, comprising: obtaining, by a processing device, an indication of a fluid level of an auxiliary receiver of a refrigeration system, wherein the refrigeration system comprises a pressure exchanger (PX) configured to receive a first fluid from a first gas cooler, receive a second fluid from the auxiliary receiver, and exchange pressure between the first fluid and the second fluid; generating a first control signal based on the fluid level of the auxiliary receiver; and providing the first control signal to a first control valve, wherein the first control valve is configured to enable flow of fluid from the auxiliary receiver to a main receiver based on the first control signal.

26. The method of claim 25, further comprising: obtaining an indication of fluid pressure of the first gas cooler; generating a second control signal based on the fluid pressure of the first gas cooler; and providing the second control signal to a motor of the PX, wherein the motor of the PX is configured to adjust a speed of operation of the PX based on the second control signal.

27. The method of claim 25, further comprising: obtaining an indication of a pressure differential between the auxiliary receiver and the main receiver; generating a third control signal based on the pressure differential between the auxiliary receiver and the main receiver; and providing the third control signal to a second control valve, wherein the second control valve is coupled to provide first fluid from the first gas cooler to the auxiliary receiver, and wherein the second control valve is configured to maintain a target pressure differential between the auxiliary receiver and the main receiver based on the third control signal.

28. The method of claim 25, further comprising: obtaining an indication of a travel distance of the second fluid associated with a high- pressure outlet of the PX; generating a fourth control signal based on the travel distance of the second fluid associated with the high-pressure outlet; and providing the fourth control signal to a third control valve, wherein the third control valve is coupled to determine fluid flow of the second fluid from the high-pressure outlet of the PX through a second gas cooler to the auxiliary receiver based on an opening of the third control valve, and wherein the third control valve is configured to adjust the opening of the third control valve based on the fourth control signal.

29. The method of claim 28, wherein the indication of the travel distance is based on a measured mass flow of the second fluid, and a measured density of the second fluid.

30. The method of claim 28, further comprising: obtaining an indication of fluid temperature at an outlet of the second gas cooler; generating a fifth control signal based on the fluid temperature; and providing the fifth control signal to a device for adjusting heat transfer from the second gas cooler.

31. The method of claim 25, further comprising: obtaining an indication of a travel distance of the second fluid associated with a low- pressure inlet of the PX; generating a sixth control signal based on the travel distance of the second fluid associated with the low-pressure inlet; and providing the sixth control signal to a fourth control valve, wherein the fourth control valve is coupled to determine fluid flow of the second fluid from the auxiliary receiver to the low-pressure inlet, and wherein the fourth control valve adjusts an opening of the fourth control valve based on the sixth control signal.

32. A method comprising: obtaining, by a processing device, an indication of a pressure differential between a main receiver and an auxiliary receiver of a refrigeration system, wherein the auxiliary receiver and a pressure exchanger (PX) are configured to receive a first fluid from a first gas cooler, wherein the auxiliary receiver is configured to provide second fluid to the PX, wherein the PX is configured to exchange pressure between the first fluid and the second fluid, and wherein the main receiver is configured to receive the first fluid from the PX; generating a first control signal based on the pressure differential; and providing the first control signal to a first control valve coupled between the first gas cooler and the auxiliary receiver, wherein the first control valve is configured to adjust an opening of the first control valve based on the first control signal.

33. The method of claim 32, further comprising: obtaining an indication of a fluid level of the auxiliary receiver; generating a second control signal based on the fluid level of the auxiliary receiver; and providing the second control signal to a second control valve, wherein the second control valve is coupled between the auxiliary receiver and the main receiver, and wherein the second control valve is configured to adjust an opening of the second control valve based on the second control signal.

34. The method of claim 32, further comprising: obtaining an indication of fluid pressure of the first gas cooler; generating a third control signal based on the fluid pressure of the first gas cooler; and providing the third control signal to a motor of the PX, wherein the motor of the PX is configured to adjust a speed of operation of the PX based on the third control signal.

35. The method of claim 32, further comprising: obtaining an indication of a travel distance of the second fluid associated with a high- pressure outlet of the PX; generating a fourth control signal based on the travel distance of the second fluid associated with the high-pressure outlet; and providing the fourth control signal to a third control valve, wherein the third control valve is coupled to determine fluid flow of the second fluid from the high-pressure outlet of the PX through a second gas cooler to the auxiliary receiver based on an opening of the third control valve, and wherein the third control valve is configured to adjust the opening of the third control valve based on the fourth control signal.

36. The method of claim 35, wherein the indication of the travel distance is based on a measured mass flow of the second fluid, and a measured density of the second fluid.

37. The method of claim 35, further comprising: obtaining an indication of fluid temperature at an outlet of the second gas cooler; generating a fifth control signal based on the fluid temperature; and providing the fifth control signal to a device for adjusting heat transfer from the second gas cooler.

38. The method of claim 32, further comprising: obtaining an indication of a travel distance of the second fluid associated with a low- pressure inlet of the PX; generating a sixth control signal based on the travel distance of the second fluid associated with the low-pressure inlet; and providing the sixth control signal to a fourth control valve, wherein the fourth control valve is coupled to determine fluid flow of the second fluid from the auxiliary receiver to the low-pressure inlet, and wherein the fourth control valve adjusts an opening of the fourth control valve based on the sixth control signal.

39. A non-transitory machine-readable storage medium storing instructions which, when executed, cause a processing device to perform any of the methods of claims 17 through 38.

40. A system, comprising memory and a processing device coupled to the memory, wherein the processing device is configured to perform any of the methods of claims 17 through 38.