CN117128679A

CN117128679A - Overheat control of heating, ventilation, air conditioning and refrigeration systems including dynamic receivers

Info

Publication number: CN117128679A
Application number: CN202310618784.3A
Authority: CN
Inventors: Y·J·伦博特; P·D·M·蒂塞兰; G·马蒂欧斯; S·D·蔻尼格塞克
Original assignee: Trane International Inc
Current assignee: Trane International Inc
Priority date: 2022-05-27
Filing date: 2023-05-29
Publication date: 2023-11-28
Also published as: EP4283218A1

Abstract

A dynamic receiver included in a heating, ventilation, air conditioning and refrigeration (HVACR) system is connected in parallel with an expander of the HVACR system. The dynamic receiver allows control of the refrigerant charge of the HVACR system in response to different operating conditions. The dynamic receiver may be filled or emptied in response to the supercooling observed in the HVACR system compared to the desired supercooling for the various modes of operation. The flow through the expander of the HVACR system may be controlled to account for the mass flow through the outlet valve of the dynamic receiver when the dynamic receiver is empty, thereby preventing or reducing instability or effects on system parameters (e.g., suction superheat).

Description

Overheat control of heating, ventilation, air conditioning and refrigeration systems including dynamic receivers

Technical Field

The present invention relates to a dynamic liquid receiver in a refrigeration circuit and a control strategy for a dynamic liquid receiver.

Background

The refrigeration circuit typically includes a liquid receiver with a fixed filling process. Thus, the refrigerant charge in the receiver is maintained at a fixed level. The effect of the receiver filling at different loads and different parts of the operating diagram on efficiency is different. The fixed receiver fill setting must be improved locally at the expense of certain operating conditions to increase efficiency in order to set it to a value that provides adequate efficiency over different portions of the operating diagram.

Disclosure of Invention

By dynamically controlling the refrigerant charge in the system, more efficient operating conditions can be selected for full and part load conditions, and the operating profile of the refrigeration system can be increased.

When working fluid is added to the system by being discharged from the dynamic receiver into the circulatory flow, the change in mass flow may have a chain effect on the operating parameters of the HVACR system (e.g., suction superheat). Some of these effects may be delayed until 30 seconds or more after the working fluid is expelled, from being detected or responded to. These effects can lead to instability and to failures such as activating a low voltage power down, a low suction overheat timed power down, an excessive defrost cycle, activating a high voltage power down, etc. By controlling the expander while taking into account emissions from the dynamic receiver, mass flow may be maintained more stable, these effects reduced or eliminated, and related failure modes of the HVACR system reduced or eliminated.

In one embodiment, a heating, ventilation, air conditioning and refrigeration (HVACR) system includes a compressor, a first heat exchanger, an expander, a second heat exchanger, and a dynamic receiver in a fluid circuit. The dynamic receiver is connected in parallel with the expander relative to the fluid circuit. The HVACR system also includes a fluid line configured to communicate discharge from the compressor to the dynamic receiver.

In one embodiment, the HVACR system further includes a four-way valve.

In one embodiment, the HVACR system further includes a third heat exchanger. The first heat exchanger is configured to exchange heat between a working fluid and a first process fluid in the fluid loop, the second heat exchanger is configured to exchange heat between the working fluid and a second process fluid, and the third heat exchanger is configured to exchange heat with ambient air.

In an embodiment, the HVACR system further includes a controller configured to operate an inlet valve positioned directly upstream of the dynamic receiver, an outlet valve positioned directly downstream of the dynamic receiver, and a compressor discharge injection valve positioned along the fluid line to regulate an amount of working fluid stored in the dynamic receiver. In an embodiment, the controller is configured to determine a target amount of working fluid to be stored in the dynamic receiver based on the measured liquid line subcooling value and subcooling threshold value. In one embodiment, the measured subcooling value of the liquid line is based on a liquid line temperature measurement and a liquid line pressure measurement. In one embodiment, the target amount of working fluid is also based on K _P Values. In an embodiment, the controller is configured to reduce the amount of working fluid stored in the dynamic receiver up to a target amount of working fluid by opening the outlet valve and the compressor discharge injection valveIs stored in the dynamic receiver. In an embodiment, the controller is configured to increase the amount of working fluid stored in the dynamic receiver by opening the inlet valve until a target amount of working fluid is stored in the dynamic receiver. In an embodiment, the supercooling threshold is based on an operating mode of the HVACR system.

A method of controlling a heating, ventilation, air conditioning and refrigeration (HVACR) system according to an embodiment includes determining, using a controller, a target amount of working fluid to be stored in a dynamic receiver included in the HVACR system, the target amount being based on a subcooling threshold and a measured subcooling value; the method further includes comparing an amount of working fluid in the dynamic receiver with the target amount; when the amount of working fluid in the dynamic receiver exceeds the target amount, the working fluid is removed from the dynamic receiver by opening an outlet valve immediately downstream of the dynamic receiver and opening a compressor discharge injection valve disposed along a fluid line connecting the discharge of the compressor of the HVACR system to the dynamic receiver. When the amount of working fluid in the dynamic receiver is less than the target amount, the working fluid is added to the dynamic receiver by opening an inlet valve immediately upstream of the dynamic receiver relative to the working fluid flow path in the HVACR system. The dynamic receiver is connected in parallel with an expander included in the HVACR system.

In one embodiment, the measured liquid line subcooling value is based on a liquid line temperature measurement and a liquid line pressure measurement. In one embodiment, the target amount of working fluid is also based on K _P Values. In an embodiment, the supercooling threshold is based on an operating mode of the HVACR system.

In one embodiment, a heating, ventilation, air conditioning, and refrigeration (HVACR) system includes a fluid circuit including a compressor, a first heat exchanger, an expander, and a second heat exchanger. The HVACR system also includes a dynamic receiver in parallel with the expander relative to the fluid circuit; and an outlet valve configured to control flow from the dynamic receiver to the fluid circuit. The HVACR system also includes a controller configured to determine a mass flow rate through the outlet valve and to control the expander based on the flow rate through the outlet valve.

In an embodiment, the HVACR system further includes a first pressure sensor configured to measure pressure at the dynamic receiver and a second pressure sensor configured to measure pressure between the expander and the second heat exchanger. In an embodiment, the controller is configured to determine the mass flow through the outlet valve based on a difference between a first pressure reading from the first pressure sensor and a second pressure reading from the second pressure sensor.

In an embodiment, the controller is configured to determine a desired total mass flow. Controlling the expander based on the flow through the outlet valve includes controlling the expander such that a sum of the mass flow through the outlet valve and the mass flow through the expander is equal to the desired total mass flow.

In one embodiment, the HVACR system further includes a four-way valve. In an embodiment, the HVACR system further comprises a third heat exchanger, and wherein the first heat exchanger is configured to exchange heat between the working fluid and the first process fluid in the fluid loop, the second heat exchanger is configured to exchange heat between the working fluid and the second process fluid, and the third heat exchanger is configured to exchange heat with ambient air.

In one embodiment, a method of controlling a heating, ventilation, air conditioning and refrigeration (HVACR) system includes determining a mass flow through an outlet valve and controlling the outlet valve based on the mass flow through the outlet valve. The HVACR system includes: a circuit including an expander, a dynamic receiver in parallel with the expander, and an outlet valve configured to control flow from the dynamic receiver to the circuit.

In an embodiment, the method includes receiving a first pressure measurement from a first pressure sensor configured to measure a pressure at the dynamic receiver and a second pressure measurement from a second pressure sensor configured to measure a pressure downstream of the expander, and wherein determining the mass flow through the outlet valve is based on a difference between the first pressure and the second pressure.

In an embodiment, the method further comprises determining a desired total mass flow. In an embodiment, controlling the outlet valve comprises controlling the mass flow through the expander such that the sum of the mass flow through the outlet valve and the mass flow through the expander is equal to the desired total mass flow.

Drawings

Fig. 1A shows a schematic diagram of a heating, ventilation, air conditioning and refrigeration (HVACR) system operating in a cooling mode according to an embodiment.

Fig. 1B shows the HVACR system of fig. 1A when operating in a heating mode.

Fig. 1C illustrates the HVACR system of fig. 1A when operating in a combined mode providing heating and cooling.

Fig. 2 shows a flow chart of logic for controlling a dynamic receiver according to an embodiment.

Fig. 3 illustrates an HVACR system operating in a cooling mode according to an embodiment.

Fig. 4 shows a flowchart of a method for controlling an HVACR system according to an embodiment.

Detailed Description

Fig. 1A shows a schematic diagram of a heating, ventilation, air conditioning and refrigeration (HVACR) system operating in a cooling mode according to an embodiment. The HVACR system 100 includes one or more compressors 102 and a four-way valve 104. The HVACR system 100 also includes a first heat exchanger 106 having a first heat exchanger isolation valve 108 between the four-way valve 104 and the first heat exchanger 106; a second heat exchanger 110 having a second heat exchanger isolation valve 112 between the four-way valve 104 and the second heat exchanger 110; and a third heat exchanger 114 having a third heat exchanger isolation valve 116. The HVACR system 100 also includes an expander 118 and a dynamic receiver 120. With respect to the direction of flow of the working fluid through the HVACR system 100, the inlet valve 122 is upstream of the dynamic receiver 120, and the outlet valve 124 is downstream of the dynamic receiver 120. A compressor discharge injection line 126 extends directly from the discharge outlet of one or more compressors 102 to the dynamic receiver 120, wherein a compressor discharge injection valve 128 is disposed along the compressor discharge injection line 126. Check valves 130 are included along the various fluid lines to allow flow in only one direction through those particular lines. The controller 132 controls at least the inlet valve 122, the outlet valve 124, and the compressor discharge injection valve 128. The controller 132 may receive data from one or more pressure sensors 134 and/or temperature sensors 136 that measure the condition of the working fluid at points in the HVACR system 100.

The HVACR system 100 is an HVACR system for providing climate control to at least one conditioned space. In the embodiment shown in fig. 1A, the HVACR system is a four-tube HVACR system, comprising separate heating and cooling lines leading to appropriate respective heat exchangers, such that one or both of heating and cooling may be provided simultaneously.

One or more compressors 102 are provided. The compressor 102 may be any suitable compressor or compressors for compressing a working fluid, such as a screw compressor, scroll compressor, or the like. Where multiple compressors 102 are included in the HVACR system 100, the compressors may be connected in parallel with each other. One or more compressors 102 discharge compressed working fluid into a discharge line that delivers the discharge to a four-way valve 104. In an embodiment, the one or more compressors 102 can be one to four compressors.

The four-way valve 104 is configured to selectively control fluid communication between the discharge of one or more compressors 102 and one of the second heat exchanger 110 and the third heat exchanger 114. The four-way valve 104 is also configured to selectively control communication of the other of the second heat exchanger 110 and the third heat exchanger 114 with the suction of the one or more compressors 102. The four-way valve may be any suitable valve or valve arrangement to provide the selectively controllable fluid communication described above.

The first heat exchanger 106 is a heat exchanger configured to receive a working fluid and exchange heat between the working fluid and a heating process fluid for providing heating. The first heat exchanger 106 may be any suitable type of heat exchanger for providing heat exchange between a working fluid and a heating process fluid. The heating process fluid may be any suitable process fluid for providing heating, such as water. The heated process fluid may be received from a heated process fluid inlet line 138 and discharged from a heated process fluid outlet line 140 at a relatively high temperature in a mode that provides heating, such as the mode shown in fig. 1B and 1C.

The first heat exchanger isolation valve 108 is a valve located between the four-way valve 104 and the first heat exchanger 106. The first heat exchanger isolation valve 108 may be any suitable valve having an open position that allows flow therethrough and a closed position that inhibits flow therethrough. The first heat exchanger isolation valve 108 may be selectively controlled based on the operating mode of the HVACR system 100, for example, closing the first heat exchanger isolation valve 108 in the cooling mode shown in fig. 1A. It should be appreciated that a valve such as the first heat exchanger isolation valve 108 or any other valve described herein may allow for a small amount of leakage in the closed position, e.g., due to wear, manufacturing tolerances or imperfections, etc., and that the closed position of the valve is understood to prohibit flow even though such leakage may occur.

In an embodiment, defrost valve 142 may be positioned along the fluid line to provide communication between expander 118 and first heat exchanger 106. Defrost valve 142 may be a controllable valve having at least a closed position that inhibits flow therethrough and an open position that allows flow. The defrost valve 142 may be placed in an open position to perform defrost operations and closed in other modes of operation of the HVACR system 100 (e.g., cooling only, heating only, and heating and cooling modes, respectively, shown in fig. 1A-1C).

The second heat exchanger 110 is a heat exchanger configured to receive a working fluid and exchange heat between the working fluid and a heat exchange medium that is different from the heated process fluid or the cooled process fluid that is heated or cooled, respectively, by the HVACR system 100. The heat exchange medium may be, for example, the ambient environment. The second heat exchanger 110 may be any suitable type of heat exchanger for providing a heat exchanger between the working fluid and the surrounding environment. In an embodiment, the ambient environment may receive heat rejected at the second heat exchanger 110 in a cooling mode such as that shown in fig. 1A, wherein the second heat exchanger 110 acts as a condenser to condense the effluent from the one or more compressors 102. In an embodiment, the working fluid may absorb heat from the ambient environment at the second heat exchanger 110, such as in the heating mode shown in fig. 1B, wherein the second heat exchanger 110 acts as an evaporator of the working fluid received from the expander 118.

A second heat exchanger isolation valve 112 is located between the four-way valve 104 and the second heat exchanger 110. The second heat exchanger isolation valve 112 may be any suitable valve having an open position that allows flow therethrough and a closed position that inhibits flow therethrough. The second heat exchanger isolation valve 112 may be selectively controlled based on the operating mode of the HVACR system 100, for example, closing the second heat exchanger isolation valve 112 in the heating and cooling modes shown in fig. 1C.

In one embodiment, a heat pump valve 144 is positioned along the fluid line to provide fluid communication between the expander 118 and the second heat exchanger 110. The heat pump valve 144 is a controllable valve having at least an open position that allows flow from the expander 118 to the second heat exchanger 110 and a closed position that inhibits flow from the expander 118 to the second heat exchanger 110. For example, during a heating operation (such as the heating operation of HVACR system 100 shown in fig. 1B), heat pump valve 144 may be in an open position. Heat pump valve 144 may be closed in at least some other modes of operation, such as the cooling mode of operation shown in fig. 1A and the heating and cooling modes of operation shown in fig. 1C.

The third heat exchanger 114 is a heat exchanger configured to receive a working fluid and exchange heat between the working fluid and a cooling process fluid for providing cooling. The third heat exchanger 114 may be any suitable type of heat exchanger for providing heat exchange between the working fluid and the cooling process fluid. The cooling process fluid may be any suitable process fluid for providing cooling, such as water, a combination of water and ethylene glycol, or the like. The cooling process fluid may be received from the cooling process fluid inlet line 146 and discharged from the cooling process fluid outlet line 148 at a relatively low temperature in modes that provide cooling, such as those shown in fig. 1A and 1C. The third heat exchanger 114 operates as an evaporator to evaporate the working fluid received from the expander 118 by absorbing heat from the cooling process fluid.

Third heat exchanger isolation valve 116 is a valve located between four-way valve 104 and/or the suction inlet of one or more compressors 102 and third heat exchanger 114. The third heat exchanger isolation valve 116 may be any suitable valve having an open position that allows flow therethrough and a closed position that inhibits flow therethrough. The third heat exchanger isolation valve 116 may be selectively controlled based on the operating mode of the HVACR system 100, for example, closing the third heat exchanger isolation valve 116 in the heating mode shown in fig. 1B, and opening the third heat exchanger isolation valve 116 in the cooling mode shown in fig. 1A and the heating and cooling modes shown in fig. 1C, respectively.

The cooling valve 150 is positioned along the fluid line from the expander 118 to the third heat exchanger 114. The cooling valve 150 is a controllable valve having at least an open position that allows flow from the expander 118 to the third heat exchanger 114 and a closed position that inhibits flow from the expander 118 to the third heat exchanger 114. For example, during a cooling operation (such as the cooling operation of HVACR system 100 shown in fig. 1A or the heating and cooling operation shown in fig. 1C), cooling valve 150 may be in an open position. The cooling valve 150 may be closed in at least some other modes of operation, such as the heating mode of operation shown in fig. 1B.

The expander 118 is configured to expand the working fluid received from one of the first heat exchanger 106 or the second heat exchanger 110. The expander 118 may be any suitable expander for the working fluid, such as an expansion valve, an expansion plate, an expansion vessel, one or more expansion holes, or any other known suitable structure for expanding the working fluid.

Dynamic receiver 120 is a liquid receiver configured to store a working fluid. Dynamic receiver 120 may be any suitable receiver for storing a working fluid such as, but not limited to, a reservoir, container, tank, or other suitable volume. The dynamic receiver 120 may store the working fluid as a liquid. The working fluid stored in the dynamic receiver 120 is removed from circulation through the rest of the HVACR system 100 when stored, allowing the amount of working fluid circulated in the HVACR system 100 to be controlled by varying the amount of working fluid stored in the dynamic receiver 120. The amount of working fluid in dynamic receiver 120 may be controlled in response to operating modes and/or operating conditions, such as by controller 132 controlling inlet valve 122, outlet valve 124, and compressor discharge injection valve 128, or according to the method shown in fig. 2 and described below. The dynamic receiver 120 may be sized such that it may hold enough liquid working fluid to cover the difference in charge between any or all modes of operation of the HVACR system 100. The size of the dynamic receiver 120 may be such that the amount of working fluid that may be stored further accounts for transitions between those modes of operation or other operating conditions. For example, in the embodiment shown in fig. 1A-1C, the dynamic receiver 120 may be sized such that it may accommodate up to about 60% of the maximum charge of working fluid of the HVACR system 100. In one embodiment, the dynamic receiver 120 may be sized such that it may accommodate up to about 40% of the maximum charge of working fluid of the HVACR system 100. The liquid level shown in the dynamic receiver 120 in fig. 1A illustrates one potential approximation of the working fluid for the operating mode shown in fig. 1A.

With respect to the direction of flow of the working fluid through the HVACR system 100, the inlet valve 122 is upstream of the dynamic receiver 120, and the outlet valve 124 is downstream of the dynamic receiver 120. Inlet valve 122 is a controllable valve having an open position allowing the passage of working fluid and a closed position prohibiting the passage of flow. When in the open position, the inlet valve 122 allows the working fluid upstream from the expander 118 to pass to the dynamic receiver 120, where the working fluid may be retained, thereby reducing the charge of working fluid circulated through the HVACR system 100. The outlet valve 124 is a controllable valve having an open position allowing the working fluid to pass therethrough and a closed position prohibiting the flow therethrough. When in the open position, outlet valve 124 allows working fluid to pass from dynamic receiver 120 into the flow of working fluid downstream of expander 118, thereby rejoining the working fluid being circulated through HVACR system 100.

A compressor discharge injection line 126 extends directly from the discharge outlet of one or more compressors 102 to the dynamic receiver 120, wherein a compressor discharge injection valve 128 is disposed along the compressor discharge injection line 126. The compressor discharge injection line 126 provides direct fluid communication between the discharge of one or more compressors and the dynamic receiver 120 such that the compressor discharge may be directed to the dynamic receiver 120 without passing through the four-way valve 104 or any further downstream components of the HVACR system 100, such as the first heat exchanger 106, the second heat exchanger 110, and the like. The compressor discharge injection valve 128 is a controllable valve having at least an open position allowing flow therethrough and a closed position prohibiting flow. When the compressor discharge injection valve 128 is open, some of the discharge from one or more compressors 102 may pass into the dynamic receiver 120. Discharged from one or more compressors 102 is a working fluid in the form of a relatively hot gas that may displace a relatively large mass of liquid working fluid stored in dynamic receiver 120 to facilitate removal of the working fluid from dynamic receiver 120. The working fluid displaced from the dynamic receiver 120 by the compressor discharge may pass through an outlet valve 124 to join the working fluid stream downstream of the expander 118.

As shown in fig. 1A-1C, the check valve 130 may be positioned along various fluid lines in the HVACR system 100. The check valve 130 may be a passive one-way valve that allows flow through the fluid line in only one direction to facilitate operation in various modes with respective responses to flow present in the different modes of operation shown in fig. 1A-1C. The check valve 130 may be placed, for example, between the first heat exchanger 106 and the second heat exchanger 110 or the third heat exchanger 114, between the outlet valve 124 and the rest of the HVACR system 100.

The controller 132 controls at least the inlet valve 122, the outlet valve 124, and the compressor discharge injection valve 128 to control the amount of working fluid circulated in the HVACR system 100 and the amount of working fluid stored in the dynamic receiver 120. The controller 132 may control the amount of working fluid stored in the dynamic receiver 120 to achieve a target amount or to bring the amount of working fluid stored in the dynamic receiver 120 within a defined range. The controller 132 is operatively connected to the inlet valve 122, the outlet valve 124, and the compressor discharge injection valve 128 such that commands may be sent from the controller 132 to these valves. The operative connection may be, for example, a direct wired connection or a wireless communication. The controller 132 may be configured to open the inlet valve 122 when working fluid is to be added to the dynamic receiver 120. The controller 132 may be configured to open the compressor discharge injection valve 128 and the outlet valve 124 when working fluid is to be removed from the dynamic receiver 120. The controller 132 may be further configured to close the inlet valve 122 when working fluid is retained in the dynamic receiver 120 or removed from the dynamic receiver 120. The controller 132 may be further configured to close the compressor discharge injection valve 128 and the outlet valve 124 when working fluid is retained or added to the dynamic receiver 120.

The controller 132 may also be configured to determine a target amount or a defined range of the amount of working fluid stored in the dynamic receiver 120. In an embodiment, the target amount or limit may be determined based on a current operating mode of the HVACR system 100 (such as the cooling mode shown in fig. 1A, the heating mode shown in fig. 1B, or the heating and cooling modes shown in fig. 1C). In an embodiment, the target amount or limit range may be determined based on operating conditions of the HVACR system 100 (such as a position on an operating map of the HVACR system 100). In an embodiment, the target amount or defined range may be based on a subcooling value of the HVACR system 100, such as when compared to a subcooling threshold. The supercooling threshold, in turn, may be associated with a particular mode of operation or operating condition. In one embodiment, a fixed subcooling threshold is set for each mode of operation. In an embodiment, the subcooling threshold may be adapted to optimize efficiency, or allow a larger operating envelope (operating envelope) of the HVACR system 100, such as by providing a range or otherwise allowing some degree of deviation from the subcooling threshold. The controller 132 may be further configured to control the fluid level in the dynamic receiver 120 not only in a particular mode of operation, but also during transitions between modes of operation (such as from heating only to heating and cooling, heating only to cooling only, cooling only to heating only, etc.).

Pressure sensor 134 and/or temperature sensor 136 may be included to measure the pressure and temperature of the working fluid at one or more locations within HVACR system 100. Pressure sensor 134 may be any suitable pressure sensor for measuring the pressure of the working fluid at a point within HVACR system 100. The temperature sensor 136 may be any suitable temperature sensor for measuring the temperature of the working fluid at a point within the HVACR system 100. In an embodiment, the pressure sensor 134 and/or the temperature sensor 136 may be configured to provide pressure and/or temperature measurements to the controller 132, for example, via a wired connection or wireless communication. In an embodiment, at least one pressure sensor 134 and at least one temperature sensor 136 may be included along the liquid line of the HVACR system 100 between the first heat exchanger 106 or the second heat exchanger 110 (depending on which is used as a condenser in the current mode of operation) and the expander 118. In an embodiment, the pressure sensor 134 and the temperature sensor 136 disposed along the liquid line may be located immediately upstream of the expander 118 with respect to the direction of flow of the working fluid. In an embodiment, at least one pressure sensor 134 and/or temperature sensor 136 may be disposed at the suction inlet of one or more compressors 102. In an embodiment, at least one pressure sensor 134 and/or temperature sensor 136 may be disposed at the discharge of one or more compressors 102. The pressure sensor 134 and/or the temperature sensor 136 may further be disposed at other points of interest along the HVACR system 100, such as providing a temperature sensor just upstream of the third heat exchanger 114 with respect to the direction of flow of the working fluid through the HVACR system 100.

In the embodiment shown in fig. 1A, where HVACR system 100 is used as a chiller, four-way valve 104 directs the discharge from one or more compressors 102 to second heat exchanger 110 and provides a path from third heat exchanger 114 back to the suction inlet of one or more compressors 102. The four-way valve also provides a passageway for fluid communication between the first heat exchanger 106 and the suction inlet of the one or more compressors 102, however in fig. 1A, the passageway is closed from the first heat exchanger 106 due to the first heat exchanger isolation valve 108 being in the closed position.

Fig. 1B illustrates the HVACR system 100 of fig. 1A when operating in a heating mode. In the heating mode shown in fig. 1B, the four-way valve 104 is in a position wherein the discharge of the one or more compressors 102 is directed to the first heat exchanger 106, and wherein the second heat exchanger 110 is in communication with the suction inlet of the one or more compressors 102. The cooling valve 150 and the third heat exchanger isolation valve 116 are in a closed position, thereby preventing the working fluid from flowing to the third heat exchanger 114. In this embodiment, the working fluid discharged by the one or more compressors 102 is transferred to the first heat exchanger 106 where the working fluid discharges heat and the heated process fluid receives the heat. The working fluid then continues to enter the expander 118, and when the inlet valve 122 is opened based on a command from the controller 132, some of the working fluid may pass through the inlet valve 122 to the dynamic receiver 120 before reaching the expander 118. The working fluid expanded by expander 118 and any working fluid exiting dynamic receiver 120 via outlet valve 124 when outlet valve 124 is open is then transferred to second heat exchanger 110 through heat pump valve 144 in the open position. At the second heat exchanger 110, the working fluid absorbs heat from ambient air and is then directed through a four-way valve to the suction inlet of the one or more compressors 102. Thus, in the heating mode shown in fig. 1B, the HVACR rejects heat to the heated process fluid at the first heat exchanger 106, and absorbs heat from the ambient environment at the second heat exchanger 110, acting as a heat pump to heat the process fluid.

In the heating mode shown in fig. 1B, the amount of working fluid stored in the dynamic receiver 120 may be relatively greater than the amount stored in the dynamic receiver 120 during the cooling mode shown in fig. 1A, which means that a smaller volume of working fluid is circulated through the HVACR system 100. However, it should be appreciated that the amount of working fluid in the dynamic receiver 120 and circulated through the remainder of the HVACR system 100 may be determined based, inter alia, on the particular operating conditions and other factors as described herein.

Fig. 1C illustrates the HVACR system 100 of fig. 1A when operating in a combined mode that provides heating and cooling. In the heating and cooling mode shown in fig. 1C, the four-way valve 104 is in a position where the discharge of one or more compressors 102 is directed to the first heat exchanger 106. The second heat exchanger isolation valve 112 and the heat pump valve 144 are in a closed position preventing the working fluid from flowing to the second heat exchanger 110. The four-way valve 104 also provides communication between the third heat exchanger 114 and the suction ports of the one or more compressors 102. In this embodiment, the working fluid discharged by the one or more compressors 102 is transferred to the first heat exchanger 106 where the working fluid discharges heat and the heated process fluid receives the heat. The working fluid then continues to enter the expander 118, and when the inlet valve 122 is opened based on a command from the controller 132, some of the working fluid may pass through the inlet valve 122 to the dynamic receiver 120 before reaching the expander 118. The working fluid 118 expanded by the expander and any working fluid exiting the dynamic receiver 120 via the outlet valve 124 is then transferred to the third heat exchanger 114 through the cooling valve 150 in the open position. At the third heat exchanger 114, the working fluid absorbs heat from the cooling process fluid and then transfers to the suction inlet of the one or more compressors 102. Thus, in the heating and cooling mode shown in fig. 1C, the HVACR rejects heat to the heating process fluid at the first heat exchanger 106, and absorbs heat from the cooling process fluid at the third heat exchanger 114, cooling the cooling process fluid while also heating the heating process fluid.

In the heating and cooling modes shown in fig. 1C, the amount of working fluid stored in the dynamic receiver 120 may be relatively greater than the amount stored in the dynamic receiver 120 during the cooling mode shown in fig. 1A and relatively less than the amount stored in the dynamic receiver 120 during the heating mode shown in fig. 1B, meaning that an intermediate volume of working fluid circulates through the HVACR system 100 in this mode. However, it should be appreciated that the amount of working fluid in the dynamic receiver 120 and circulated through the remainder of the HVACR system 100 may be determined based, inter alia, on the particular operating conditions and other factors as described herein.

Although fig. 1A-1C illustrate an HVACR system that includes three heat exchangers and piping therein selected to meet different heating and/or cooling requirements, including simultaneous heating and cooling, it should be understood that embodiments may include other HVACR system designs, such as air conditioning, common heat pump systems, and the like. Examples of air conditioners or coolers according to an embodiment may include, for example, only active elements of HVACR system 100 when in the cooling mode shown in fig. 1A. For example, when in the heating mode shown in fig. 1C, an example of a heat pump may include only the active elements of HVACR system 100. These embodiments will continue to include a dynamic receiver 120, an inlet valve 122, and an outlet valve 124 in parallel with an expander (e.g., expander 118), and also include a compressor discharge injection line 126. An HVACR system according to embodiments may include any two heat exchangers, such as two of the first heat exchanger 106, the second heat exchanger 110, and the third heat exchanger 114, wherein one of the heat exchangers operates as a condenser and the other operates as an evaporator. Although the HVACR system 100 shown in fig. 1A-1C includes the first heat exchanger 106, the second heat exchanger 110, and the third heat exchanger 114, any one or more heat exchangers may be eliminated depending on the particular system (e.g., in systems that strictly provide heating or cooling, or in systems that are standard reversible heat pumps).

In addition to the modes shown in fig. 1A-1C, various valves including the first heat exchanger isolation valve 108, the second heat exchanger isolation valve 112, and the third heat exchanger isolation valve 116, the cooling valve 150, the heat pump valve 144, and the defrost valve 142, and the four-way valve 104 may be positioned in combination with one another to achieve other modes of operation of the HVACR system 100, such as purging, defrosting, or recovering lubricant. The check valve 130 is responsive to the direction of flow provided by the control of those other valves to achieve a particular desired operation of the HVACR system 100. Examples of other modes that may be included include defrost modes for a particular HVACR system 100 or any other suitable type of operation. The control of the dynamic receiver 120 in this mode may be to provide a minimum working fluid charge or near a minimum working fluid charge within the HVACR system 100 for a particular mode of operation.

Fig. 2 shows a flow chart of logic for controlling a dynamic receiver of a heating, ventilation, air conditioning and refrigeration (HVACR) system, according to an embodiment. The method 200 includes one of obtaining a subcooling threshold 202, obtaining a measured subcooling value 204, determining a target amount of working fluid 206, comparing 208 the target amount of working fluid with an actual amount of working fluid in a receiver, and performing adding 210 or removing 212 working fluid to or from the receiver based on the comparison. Optionally, obtaining measured subcooling at 204 may include obtaining a liquid line temperature 214 and/or obtaining a liquid line pressure 216.

A supercooling threshold is obtained at 202. The supercooling threshold may be a particular supercooling value or range of supercooling values associated with a particular operating mode (such as the heating, cooling, or heating and cooling modes shown in fig. 1A-1C), or for particular operating conditions (such as or other operating parameters). The supercooling threshold, in turn, may be associated with a particular mode of operation or operating condition. In one embodiment, a fixed subcooling threshold is set for each mode of operation. In an embodiment, the subcooling threshold may be adapted to optimize efficiency, or allow a larger operating envelope of the HVACR system 100, such as by providing a range or otherwise allowing some degree of deviation from the subcooling threshold.

At 204, a measured subcooling may be obtained. Optionally, obtaining measured subcooling at 204 may include obtaining a liquid line temperature 214 and/or obtaining a liquid line pressure 216. In one embodiment, the measured subcooling is a value representative of the subcooling that is currently occurring in the HVACR system. The measured subcooling may be calculated from the temperature in the liquid line of the HVACR system obtained at 214 and/or the pressure in the liquid line obtained at 216. For example, the measured subcooling may be obtained by the difference between the saturated liquid temperature and the liquid line temperature. In an embodiment, the saturated liquid temperature may be determined based on the pressure in the liquid line obtained at 216. Alternatively, a smoothing function may be used when obtaining the measured subcooling at 204. Obtaining the liquid line temperature 214 may include measuring a temperature in a liquid line that conveys the working fluid from a heat exchanger that functions as a condenser to an expander. The liquid line temperature may be obtained at 214 by measuring the temperature using a temperature sensor disposed along the liquid line (e.g., directly upstream of the expander). Obtaining the liquid line pressure at 216 may include measuring the pressure in the liquid line, for example, by a pressure sensor disposed along the liquid line (such as directly upstream of the expander). In an embodiment, the temperature sensor used at 214 and the pressure sensor used at 216 may be located at approximately the same location along the fluid line.

A target amount of working fluid is determined at 206. The target amount of working fluid may be based on a difference between the measured subcooling and the subcooling degree threshold. In one embodiment, the target amount may be further based on K of the HVACR system _P Value of K _P Is the gain adjustment factor. K (K) _P May be used, at least in part, to match the HVACR system dynamic receiver to control actions to account for the reactive nature of operating valves controlling flow into or out of the dynamic receiver. In an embodiment, the target amount may be directly based on a current operating mode of the HVACR system, such as heating, cooling, heating and cooling, purging, defrosting, or other possible operating modes of the HVACR system, each of which may have a charge amount associated with the operating mode.

At 208, the target amount of working fluid is compared to the actual amount of working fluid in the receiver. Based on the comparison, the method 200 may proceed to add working fluid to the receiver 210 when the actual amount of working fluid in the receiver is less than the target amount, or remove working fluid from the receiver 212 when the actual amount of working fluid in the receiver exceeds the target amount.

At 210, a working fluid may be added to the receiver. Adding working fluid to the receiver 210 may include opening an inlet valve. Adding working fluid to the receiver 210 may further include ensuring that both the receiver outlet valve and the compressor discharge injection valve are closed. Some working fluid passing through the fluid circuit of the HVACR system enters the receiver through the inlet valve, where it can be stored. A fluid line connected to the receiver to introduce the working fluid into the receiver may be located upstream of an expander of the HVACR system with respect to a direction of flow of the working fluid through the HVACR system. Based on the comparison performed at 208, adding working fluid 210 from the receiver may be performed as long as the amount of working fluid is below the target amount of working fluid determined at 206.

The working fluid may be removed from the receiver at 212. Working fluid 212 may be removed from the receiver by opening the outlet valve of the receiver and opening the compressor discharge injection valve. Removing working fluid 212 from the receiver may further include ensuring that an inlet valve for the receiver is closed. The compressor discharge fluid introduced by the compressor discharge injection valve is a hot gas and the introduction of the compressor discharge fluid may drive out a relatively large amount of working fluid stored in the receiver, which leaves the receiver via the outlet valve. The working fluid removed from the receiver is introduced into the HVACR system downstream of the expander of the HVACR system with respect to the direction of flow of the working fluid through the HVACR system. At 212, the working fluid may continue to be removed from the receiver as long as the amount of working fluid remains greater than the target amount of working fluid, as determined by the comparison at 208.

Fig. 3 illustrates an HVACR system operating in a cooling mode according to an embodiment. The HVACR system 300 includes one or more compressors 302 and a four-way valve 304. The HVACR system 300 also includes a first heat exchanger 306 having a first heat exchanger isolation valve 308 between the four-way valve 304 and the first heat exchanger 306; a second heat exchanger 310 having a second heat exchanger isolation valve 312 between the four-way valve 304 and the second heat exchanger 310; and a third heat exchanger 314 having a third heat exchanger isolation valve 316. The HVACR system 300 also includes an expander 318 and a dynamic receiver 320. The inlet valve 322 is upstream of the dynamic receiver 320 and the outlet valve 324 is downstream of the dynamic receiver 320 with respect to the direction of flow of the working fluid through the HVACR system 300. A compressor discharge injection line 326 extends directly from the discharge outlet of one or more compressors 302 to the dynamic receiver 320, wherein a compressor discharge injection valve 328 is disposed along the compressor discharge injection line 326. Check valves 330 are included along the various fluid lines to allow flow in only one direction through those particular lines. The controller 332 controls at least the expander 318 and the inlet valve 322, the outlet valve 324, and the compressor discharge injection valve 328. The controller 332 may receive data from one or more pressure sensors 334 and/or temperature sensors 336 that measure the condition of the working fluid at points in the HVACR system 300.

The HVACR system 300 is an HVACR system for providing climate control to at least one conditioned space. In the embodiment shown in fig. 3, the HVACR system is a four-tube HVACR system, comprising separate heating and cooling lines leading to appropriate respective heat exchangers, such that one or both of heating and cooling may be provided simultaneously.

One or more compressors 302 are provided. The compressor 302 may be any suitable compressor or compressors for compressing a working fluid, such as a screw compressor, scroll compressor, or the like. Where multiple compressors 302 are included in the HVACR system 300, the compressors may be connected in parallel with each other. One or more compressors 302 discharge compressed working fluid into a discharge line that delivers the discharge to a four-way valve 304. In an embodiment, the one or more compressors 302 can be one to four compressors.

The four-way valve 304 is configured to selectively control fluid communication between the discharge of one or more compressors 302 and one of the second heat exchanger 310 and the third heat exchanger 314. The four-way valve 304 is also configured to selectively control communication of the other of the second heat exchanger 310 and the third heat exchanger 314 with the suction of the one or more compressors 302. The four-way valve may be any suitable valve or arrangement of valves to provide the selectively controllable fluid communication described above.

The first heat exchanger 306 is a heat exchanger configured to receive a working fluid and exchange heat between the working fluid and a heating process fluid for providing heating. The first heat exchanger 306 may be any suitable type of heat exchanger for providing heat exchange between the working fluid and the heating process fluid. The heating process fluid may be any suitable process fluid for providing heating, such as water. Heated process fluid may be received from heated process fluid inlet line 338 and, in a mode that provides heating, discharged from heated process fluid outlet line 340 at a relatively high temperature. In the cooling mode shown in fig. 3, the first heat exchanger is not connected in the circuit and the working fluid is not circulated.

The first heat exchanger isolation valve 308 is a valve located between the four-way valve 304 and the first heat exchanger 306. The first heat exchanger isolation valve 308 may be any suitable valve having an open position that allows flow therethrough and a closed position that inhibits flow therethrough. The first heat exchanger isolation valve 308 may be selectively controlled based on the operating mode of the HVACR system 300, e.g., the first heat exchanger isolation valve 308 is closed in the cooling mode shown in fig. 3. It should be appreciated that a valve such as the first heat exchanger isolation valve 308 or any other valve described herein may allow for a small amount of leakage in the closed position, e.g., due to wear, manufacturing tolerances or imperfections, etc., and that the closed position of the valve is understood to prohibit flow even though such leakage may occur.

In an embodiment, a defrost valve 342 may be positioned along the fluid line to provide communication between the expander 318 and the first heat exchanger 306. Defrost valve 342 may be a controllable valve having at least a closed position that inhibits flow therethrough and an open position that allows flow. The defrost valve 342 may be placed in an open position to perform a defrost operation and closed in other modes of operation of the HVACR system 300.

The second heat exchanger 310 is a heat exchanger configured to receive a working fluid and exchange heat between the working fluid and a heat exchange medium that is different from the heated process fluid or the cooled process fluid that is heated or cooled, respectively, by the HVACR system 300. The heat exchange medium may be, for example, the ambient environment. The second heat exchanger 310 may be any suitable type of heat exchanger for providing a heat exchanger between the working fluid and the surrounding environment. In an embodiment, the ambient environment may receive heat rejected at the second heat exchanger 310 in a cooling mode such as that shown in fig. 3, wherein the second heat exchanger 310 acts as a condenser to condense the effluent from the one or more compressors 302. In an embodiment, the working fluid may absorb heat from the ambient environment at the second heat exchanger 310, such as in a heating mode, wherein the second heat exchanger 310 acts as an evaporator of the working fluid received from the expander 318.

A second heat exchanger isolation valve 312 is located between the four-way valve 304 and the second heat exchanger 310. The second heat exchanger isolation valve 312 may be any suitable valve having an open position that allows flow therethrough and a closed position that inhibits flow therethrough. The second heat exchanger isolation valve 312 may be selectively controlled based on the operating mode of the HVACR system 300, for example, closing the second heat exchanger isolation valve 312 in a combined heating and cooling mode.

In an embodiment, heat pump valve 344 is positioned along the fluid line to provide fluid communication between expander 318 and second heat exchanger 310. Heat pump valve 344 is a controllable valve having at least an open position that allows flow from expander 318 to second heat exchanger 310 and a closed position that inhibits flow from expander 118 to second heat exchanger 110. For example, during a heating operation of HVACR system 300, heat pump valve 344 may be in an open position. Heat pump valve 344 may be closed in at least some other modes of operation, such as the cooling mode of operation shown in fig. 3 or the heating and cooling modes of operation.

The third heat exchanger 314 is a heat exchanger configured to receive a working fluid and exchange heat between the working fluid and a cooling process fluid for providing cooling. The third heat exchanger 314 may be any suitable type of heat exchanger for providing heat exchange between the working fluid and the cooling process fluid. The cooling process fluid may be any suitable process fluid for providing cooling, such as water, a combination of water and ethylene glycol, or the like. The cooling process fluid may be received from a cooling process fluid inlet line 346 and provide cooling in a mode such as the cooling mode shown in fig. 3 or a combination heating and cooling mode. The cooling process fluid exits the cooling process fluid outlet line 348 at a relatively low temperature. The third heat exchanger 314 operates as an evaporator to evaporate the working fluid received from the expander 318 by absorbing heat from the cooling process fluid.

Third heat exchanger isolation valve 316 is a valve located between four-way valve 304 and/or the suction inlet of one or more compressors 302 and third heat exchanger 314. The third heat exchanger isolation valve 316 may be any suitable valve having an open position that allows flow therethrough and a closed position that inhibits flow therethrough. The third heat exchanger isolation valve 316 may be selectively controlled based on the operating mode of the HVACR system 300, for example, closing the third heat exchanger isolation valve 316 in a heating mode, in a cooling mode or a combination heating and cooling mode as shown in fig. 3, and opening the third heat exchanger isolation valve 316.

The cooling valve 350 is positioned along the fluid line from the expander 318 to the third heat exchanger 314. The cooling valve 350 is a controllable valve having at least an open position that allows flow from the expander 318 to the third heat exchanger 314 and a closed position that inhibits flow from the expander 318 to the third heat exchanger 314. For example, during a cooling operation (such as the cooling operation or the combined heating and cooling operation of the HVACR system 300 shown in fig. 3), the cooling valve 350 may be in an open position. The cooling valve 350 may be closed in at least some other modes of operation, such as a heating mode of operation.

The expander 318 is configured to expand the working fluid received from one of the first heat exchanger 306 or the second heat exchanger 310. The expander 318 may be any suitable expander for the working fluid, such as an expansion valve, an expansion plate, an expansion vessel, one or more expansion holes, or any other known suitable structure for expanding the working fluid. In the embodiment shown in fig. 3, the expander 318 is a controllable expander configured such that the mass flow rate through the expander 318 can be controlled. The expander 318 may be connected to the controller 332 such that the expander 318 is controlled based on commands received from the controller 332. For example, the expander 318 may be an electronically controllable expansion valve.

Dynamic receiver 320 is a liquid receiver configured to store a working fluid. Dynamic receiver 320 may be any suitable receiver for storing a working fluid such as, but not limited to, a reservoir, container, tank, or other suitable volume. The dynamic receiver 320 may store the working fluid as a liquid. The working fluid stored in the dynamic receiver 320 is removed from circulation through the rest of the HVACR system 300 when stored, allowing the amount of working fluid circulated in the HVACR system 300 to be controlled by varying the amount of working fluid stored in the dynamic receiver 320. The amount of working fluid in dynamic receiver 320 may be controlled in response to operating modes and/or operating conditions, such as by controller 332 controlling inlet valve 322, outlet valve 324, and compressor discharge injection valve 328, or according to the method shown in fig. 2 and described above. The dynamic receiver 320 may be sized such that it may hold enough liquid working fluid to cover the difference in charge between any or all modes of operation of the HVACR system 300. The size of the dynamic receiver 320 may be such that the amount of working fluid that may be stored further accounts for transitions between those modes of operation or other operating conditions. For example, in the embodiment shown in fig. 3, the dynamic receiver 320 may be sized such that it may accommodate up to about 60% of the maximum charge of working fluid of the HVACR system 300. In one embodiment, the dynamic receiver 320 may be sized such that it may accommodate up to about 40% of the maximum charge of working fluid of the HVACR system 300. The liquid level shown in the dynamic receiver 320 in fig. 3 illustrates one potential approximation of the working fluid for the operating mode shown in fig. 3.

The inlet valve 322 is upstream of the dynamic receiver 320 and the outlet valve 324 is downstream of the dynamic receiver 320 with respect to the direction of flow of the working fluid through the HVACR system 300. Inlet valve 322 is a controllable valve having an open position allowing the working fluid to pass therethrough and a closed position prohibiting flow therethrough. When in the open position, the inlet valve 322 allows the working fluid upstream from the expander 318 to pass to the dynamic receiver 320, where the working fluid may be retained, thereby reducing the charge of working fluid circulated through the HVACR system 300. The outlet valve 324 is a controllable valve having an open position allowing the working fluid to pass therethrough and a closed position prohibiting the flow therethrough. When in the open position, outlet valve 324 allows working fluid to pass from dynamic receiver 320 into the working fluid flow downstream of expander 318, thereby rejoining the working fluid being circulated through HVACR system 300.

A compressor discharge injection line 326 extends directly from the discharge outlet of one or more compressors 302 to the dynamic receiver 320, wherein a compressor discharge injection valve 328 is disposed along the compressor discharge injection line 326. The compressor discharge injection line 326 provides direct fluid communication between the discharge of one or more compressors and the dynamic receiver 320 such that the compressor discharge may be directed to the dynamic receiver 320 without passing through the four-way valve 304 or any further downstream components of the HVACR system 300, such as the first heat exchanger 306, the second heat exchanger 310, and the like. Compressor discharge injection valve 328 is a controllable valve having at least an open position that allows flow therethrough and a closed position that inhibits flow. When the compressor discharge injection valve 328 is open, some of the discharge from one or more compressors 302 may be transferred into the dynamic receiver 320. Discharged from one or more compressors 302 is a working fluid in the form of a relatively hot gas that may displace a relatively large mass of liquid working fluid stored in dynamic receiver 320 to facilitate removal of the working fluid from dynamic receiver 320. The working fluid displaced from the dynamic receiver 320 by the compressor discharge may pass through an outlet valve 324 to join the working fluid stream downstream of the expander 318.

As shown in fig. 3, check valve 330 may be positioned along various fluid lines in HVACR system 300. The check valve 330 may be a passive one-way valve that allows flow through the fluid line in only one direction to facilitate operation in various modes, each responsive to flow existing in a different mode of operation. The check valve 330 may be placed, for example, between the first heat exchanger 306 and the second heat exchanger 310 or the third heat exchanger 314, between the outlet valve 324 and the rest of the HVACR system 300.

The controller 332 is configured to control the expander 318. The controller 332 controls the expander 318 such that a desired mass flow of working fluid is provided to the heat exchanger downstream of the expander 318. The controller 332 may be configured to determine a mass flow rate through the outlet valve 324 based on, for example, an operational setting of the outlet valve 324 and a pressure differential across the outlet valve 324. The differential pressure may be determined based on readings from pressure sensors 334 (e.g., pressure sensors 334 configured to measure the pressure upstream of the expander and pressure sensors 334 configured to measure the pressure at the dynamic receiver 320). In an embodiment, the controller 332 may determine and control the mass flow through the expander based on the pressure differential across the expander 318 and the operating state of the expander 318. The mass flow provided to the heat exchanger downstream of the expander 318 may include the mass flow through the expander 318, as well as any mass flow through the outlet valve 324 when the outlet valve 324 is opened to return fluid from the dynamic receiver 320 to the circuit of the HVACR system 300. In an embodiment, the controller 332 is configured to obtain a desired mass flow rate, obtain a mass flow rate through the outlet valve 324, and control the expander 318 based on the mass flow rate through the outlet valve 324 such that the sum of the mass flow rate through the outlet valve 324 and the mass flow rate through the expander 318 matches the desired mass flow rate. When the outlet valve 324 is open and providing flow, the flow through the expander 318 may be correspondingly reduced by the controller 332 in order to maintain stability of the total mass flow, avoid or reduce effects on parameters of the HVACR system 300 (e.g., suction superheat, etc.).

The controller 332 may also control the inlet valve 322, the outlet valve 324, and the compressor discharge injection valve 328 to control the amount of working fluid circulated in the HVACR system 300 and the amount of working fluid stored in the dynamic receiver 320. The controller 332 may control the amount of working fluid stored in the dynamic receiver 320 to achieve a target amount or to bring the amount of working fluid stored in the dynamic receiver 320 within a defined range. The controller 332 is operatively connected to the inlet valve 322, the outlet valve 324, and the compressor discharge injection valve 328 such that commands may be sent from the controller 332 to these valves. The operative connection may be, for example, a direct wired connection or a wireless communication. The controller 332 may be configured to open the inlet valve 322 when working fluid is to be added to the dynamic receiver 320. The controller 332 may be configured to open the compressor discharge injection valve 328 and the outlet valve 324 when working fluid is to be removed from the dynamic receiver 320. Controller 332 may be further configured to close inlet valve 122 when working fluid is retained in dynamic receiver 322 or removed from dynamic receiver 320. The controller 332 may be further configured to close the compressor discharge injection valve 328 and the outlet valve 324 when working fluid is retained or added to the dynamic receiver 320.

The controller 332 may also be configured to determine a target amount or a defined range of the amount of working fluid stored in the dynamic receiver 320. In an embodiment, the target amount or limit may be determined based on a current operating mode of the HVACR system 300 (such as the cooling mode, heating mode, or a combination of heating and cooling mode shown in fig. 3). In an embodiment, the target amount or limit range may be determined based on operating conditions of the HVACR system 300 (such as a position on an operating diagram of the HVACR system 300). In an embodiment, the target amount or limit may be based on a subcooling value of the HVACR system 300, such as when compared to a subcooling threshold. The supercooling threshold, in turn, may be associated with a particular mode of operation or operating condition. In one embodiment, a fixed subcooling threshold is set for each mode of operation. In an embodiment, the subcooling threshold may be adapted to optimize efficiency, or allow a larger operating envelope of the HVACR system 300, such as by providing a range or otherwise allowing some degree of deviation from the subcooling threshold. The controller 332 may be further configured to control the fluid level in the dynamic receiver 320 not only in a particular mode of operation, but also during transitions between modes of operation (such as from heating only to heating and cooling, heating only to cooling only, cooling only to heating only, etc.).

The pressure sensor 334 is disposed in the HVACR system 300 at a location that allows for a determination of a pressure differential that affects mass flow through the expander 318 and the outlet valve 324. In the embodiment shown in fig. 3, the pressure sensor 334 includes a pressure sensor 334 configured to detect pressure at the dynamic receiver 320. The pressure sensor 334 may optionally further include a pressure sensor 334 configured to detect a pressure upstream of the expander, and a pressure sensor 334 configured to detect a pressure downstream of the expander 318, for example, along a liquid line of the HVACR system 300. Pressure sensor 334 may be any suitable pressure sensor for detecting pressure within HVACR system 300. The pressure sensors 334 are connected to the controller 332 such that the controller 332 can receive pressure readings from each pressure sensor 334, such that the controller 332 can determine the mass flow rate through the expander 318 and the outlet valve 324, and control the mass flow rate through the expander 318 to achieve a desired mass flow rate. In an embodiment, the reference pressure, for example, the reference pressure at the suction inlet of the compressor or any other suitable reference pressure for superheat control. In one embodiment, the pressure used to determine the mass flow assumes that the pressure downstream of the expander 318 and the pressure downstream of the outlet valve 324 are the same.

Additional sensors 336 may be included to measure pressure, temperature, or any other suitable parameter of the working fluid at other locations within HVACR system 300. The additional sensor 336 may be any suitable temperature sensor for measuring the temperature of the working fluid at a point within the HVACR system 300. In an embodiment, the additional sensor 336 may be configured to provide the measured value to the controller 332, such as by a wired connection or wireless communication. In an embodiment, at least one additional sensor 336 may be included along the liquid line of the HVACR system 300 between the first heat exchanger 306 or the second heat exchanger 310 (depending on which is used as a condenser in the current mode of operation) and the expander 318. In an embodiment, the sensor 336 located along the liquid line may be located immediately upstream of the expander 318 with respect to the direction of flow of the working fluid. In an embodiment, at least one sensor 336 may be disposed at the suction inlet of one or more compressors 302. In an embodiment, at least one sensor 336 may be disposed at the discharge of one or more compressors 302. The sensor 336 may be further disposed at other points of interest along the HVACR system 300, such as providing a temperature sensor immediately upstream of the third heat exchanger 314 with respect to the direction of flow of the working fluid through the HVACR system 300.

The system of fig. 3 may alternatively operate in other modes by manipulating the various valves including the first heat exchanger isolation valve 308, the second heat exchanger isolation valve 312, and the third heat exchanger isolation valve 316, the cooling valve 350, the heat pump valve 344, and the defrost valve 342, and the four-way valve 304, and these valves may be positioned in combination with one another to achieve other modes of operation of the HVACR system 300, including a heating mode (as shown in fig. 1B), a combined heating and cooling mode (as shown in fig. 1C), or other modes (such as purge, defrost, or lubricant split modes).

While fig. 3 illustrates an HVACR system including three heat exchangers and piping selected therein to meet different heating and/or cooling requirements, including simultaneous heating and cooling, it should be understood that embodiments may include other HVACR system designs, such as air conditioning, common heat pump systems, and the like. Examples of air conditioners or coolers according to an embodiment may include, for example, only active elements of HVACR system 300 when in the cooling mode shown in fig. 3. For example, an example of a heat pump may include only the active elements of an HVACR system used in a heating mode. These embodiments will continue to include a dynamic receiver 320, an inlet valve 322, and an outlet valve 324 in parallel with an expander (e.g., expander 318), and also include a compressor discharge injection line 326. These embodiments also include a controller 332, the controller 332 controlling the controllable expander 318 to control the total mass flow through the heat exchanger downstream of the expander 318. An HVACR system according to embodiments may include any two heat exchangers, such as two of the first heat exchanger 306, the second heat exchanger 310, and the third heat exchanger 314, wherein one of the heat exchangers operates as a condenser and the other operates as an evaporator. Although the HVACR system 300 shown in fig. 3 includes the first heat exchanger 306, the second heat exchanger 310, and the third heat exchanger 314, any one or more heat exchangers may be eliminated depending on the particular system (e.g., in systems that strictly provide heating or cooling, or in systems that are standard reversible heat pumps).

Fig. 4 shows a flowchart of a method for controlling an HVACR system according to an embodiment. The method 400 includes obtaining a desired total mass flow 402, determining a mass flow of the exhaust from the dynamic receiver 404, and controlling the expander to achieve the desired total mass flow 406.

A desired total mass flow is obtained at 402. In an embodiment, the desired total mass flow is derived based on operating conditions of the HVACR system (such as suction superheat or any other suitable control parameter upon which mass flow may be based). The desired total mass flow may be a desired mass flow through a heat exchanger, such as an evaporator or any other suitable heat exchanger downstream of an expander. The desired total mass flow may be based on the mass flow before opening the outlet valve of the dynamic receiver. The desired total mass flow may be determined by a controller of the HVACR system.

The mass flow of the exhaust from the dynamic receiver is obtained at 404. The mass flow rate may be obtained by any suitable means. For example, the mass flow may be derived from the state of the outlet valve and the pressure differential across the outlet valve. In an embodiment, the differential pressure may be determined based on pressure measurements from a pressure sensor at the dynamic receiver and a known pressure in the line downstream of the expander. The mass flow from the dynamic receiver is the flow through the outlet valve which re-engages the flow from the expander and passes to the heat exchanger downstream of the expander. The mass flow from the dynamic receiver obtained at 404 may be generated by operation of the dynamic receiver to control the charge of working fluid in the HVACR system, for example, in accordance with the method 200 discussed above and shown in fig. 2. The mass flow may result from removing working fluid from the dynamic receiver at 212 of the method 200 shown in fig. 2.

The expander is controlled at 406 to achieve the desired total mass flow. The expander may be any suitable expander having a controllable mass flow, such as an electronic expansion valve. The expander may be controlled at 406 such that the sum of the mass flow through the expander and the mass flow from the discharge port obtained at 404 is the desired mass flow obtained at 402. The mass flow through the expander may be controlled by any suitable control method. For example, the mass flow through the expander can be calculated based on the state of the expander and the pressure differential across the expander. The state of the expander may be controlled such that the mass flow reaches a specific value of the pressure differential currently detected in the HVACR system. The pressure differential may be a pressure differential between the pressure of the liquid line upstream of the expander and the pressure downstream of the expander.

In an embodiment, the method 400 is iterated continuously or periodically during operation of the HVACR system. In an embodiment, the method 400 iterates continuously or periodically while the outlet valve is in a state that allows flow from the dynamic receiver to the main circuit of the HVACR system. In one embodiment, the method 400 iterates as operating parameter changes of the HVACR system affect a desired mass flow. In one embodiment, the method 400 iterates as the state of the outlet valve of the dynamic receiver changes.

Aspects are:

it should be appreciated that any of aspects 1-10 may be combined with any of aspects 11-14, 15-20, or 21-24. It should be appreciated that any of aspects 11-14 may be combined with any of aspects 15-20 or 21-24. It will be appreciated that any of aspects 15-20 may be combined with any of aspects 21-24.

Aspect 1, a heating, ventilation, air conditioning and refrigeration (HVACR) system, comprising:

a compressor;

a first heat exchanger;

an expander;

a second heat exchanger;

a dynamic receiver connected in parallel with the expander relative to the fluid circuit; and

a fluid line configured to pass effluent from the compressor to the dynamic receiver.

Aspect 2, the HVACR system of aspect 1, further comprising a four-way valve.

Aspect 3, the HVACR system of aspect 2, further comprising a third heat exchanger, and wherein the first heat exchanger is configured to exchange heat between the working fluid and a first process fluid in the fluid loop, the second heat exchanger is configured to exchange heat between the working fluid and a second process fluid, and the third heat exchanger is configured to exchange heat with ambient air.

The HVACR system of any one of aspects 4, 1-3, further comprising a controller configured to operate an inlet valve positioned directly upstream of the dynamic receiver, an outlet valve positioned directly downstream of the dynamic receiver, and a compressor discharge injection valve positioned along the fluid line to regulate an amount of working fluid stored in the dynamic receiver.

Aspect 5, the HVACR system of aspect 4, wherein the controller is configured to determine a target amount of working fluid to store in the dynamic receiver based on the measured liquid line subcooling value and subcooling threshold.

The HVACR system of aspect 6, according to aspect 5, wherein the measured liquid line subcooling value is based on a liquid line temperature measurement and a liquid line pressure measurement.

The HVACR system of any one of aspects 7, 5-6, wherein the target amount of working fluid is further based on K _P Values.

The HVACR system of any one of aspects 8, 5-7, wherein the controller is configured to reduce the amount of working fluid stored in the dynamic receiver by opening the outlet valve and the compressor discharge injection valve until a target amount of working fluid is stored in the dynamic receiver.

The HVACR system of any one of aspects 9, 5-8, wherein the controller is configured to increase the amount of working fluid stored in the dynamic receiver by opening the inlet valve until a target amount of working fluid is stored in the dynamic receiver.

The HVACR system of any one of aspects 10, 5-9, wherein the subcooling threshold is based on an operating mode of the HVACR system.

Aspect 11, a method of controlling a heating, ventilation, air conditioning and refrigeration (HVACR) system, comprising:

determining, using a controller, a target amount of working fluid to be stored in a dynamic receiver included in the HVACR system, the target amount based on the subcooling threshold and the measured subcooling value;

comparing the amount of working fluid in the dynamic receiver with the target amount;

removing the working fluid from the dynamic receiver by opening an outlet valve immediately downstream of the dynamic receiver and opening a compressor discharge injection valve, the compressor discharge injection valve being disposed along a fluid line connecting the discharge of the compressor of the HVACR system to the dynamic receiver,

When the amount of the working fluid in the dynamic receiver is less than the target amount, working fluid is added to the dynamic receiver by opening an inlet valve immediately upstream of the dynamic receiver relative to a working fluid flow path in the HVACR system,

wherein the dynamic receiver is connected in parallel with an expander included in the HVACR system.

The method of aspect 12, according to aspect 11, wherein the measured subcooling value of the liquid line is based on a liquid line temperature measurement and a liquid line pressure measurement.

The method of aspect 13, any one of aspects 11-12, wherein the target amount of the working fluid is further based on K _P Values.

The method of any one of aspects 14, 11-13, wherein the subcooling threshold is based on an operating mode of the HVACR system.

Aspect 15, a heating, ventilation, air conditioning and refrigeration (HVACR) system, comprising:

a fluid circuit, the fluid circuit comprising:

a compressor;

a first heat exchanger;

an expander; and

a second heat exchanger;

a dynamic receiver connected in parallel with the expander relative to the fluid circuit;

an outlet valve configured to control flow from the dynamic receiver to the fluid circuit; and

A controller configured to determine a mass flow rate through the outlet valve and to control the expander based on the flow rate through the outlet valve.

The HVACR system of aspect 16, according to aspect 15, further comprising a first pressure sensor configured to measure pressure at the dynamic receiver and a second pressure sensor configured to measure pressure between the expander and the second heat exchanger.

The HVACR system of aspect 17, 16, wherein the controller is configured to determine the mass flow through the outlet valve based on a difference between a first pressure reading from the first pressure sensor and a second pressure reading from the second pressure sensor.

The HVACR system of any one of aspects 18, 15-17, wherein the controller is configured to determine a desired total mass flow, and the controlling of the expander based on flow through the outlet valve comprises controlling the expander such that a sum of the mass flow through the outlet valve and the mass flow through the expander is equal to the desired total mass flow.

The HVACR system of any one of aspects 19, 15-18, further comprising a four-way valve.

The HVACR system of aspect 20, aspect 19, further comprising a third heat exchanger, and wherein the first heat exchanger is configured to exchange heat between the working fluid and a first process fluid in the fluid loop, the second heat exchanger is configured to exchange heat between the working fluid and a second process fluid, and the third heat exchanger is configured to exchange heat with ambient air.

Aspect 21, a method of controlling a heating, ventilation, air conditioning and refrigeration (HVACR) system, the system comprising: a circuit comprising an expander, a dynamic receiver in parallel with the expander, and an outlet valve configured to control flow from the dynamic receiver to the circuit, the method comprising:

determining a mass flow rate through the outlet valve and; and

the outlet valve is controlled based on a mass flow rate through the outlet valve.

Aspect 22, the method of aspect 21, further comprising receiving a first pressure measurement from a first pressure sensor configured to measure pressure at the dynamic receiver; and receiving a second pressure measurement from a second pressure sensor configured to measure a pressure downstream of the expander; and wherein determining the mass flow through the outlet valve is based on a difference between the first pressure and the second pressure.

Aspect 23, the method of any of aspects 21-22, further comprising determining a desired total mass flow.

Aspect 24, the method of aspect 23, wherein controlling the outlet valve comprises controlling the mass flow through the expander such that a sum of the mass flow through the outlet valve and the mass flow through the expander is equal to the desired total mass flow.

The embodiments disclosed in the present disclosure are to be considered in all respects as illustrative and not restrictive. The scope of the application is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A heating, ventilation, air conditioning and refrigeration (HVACR) system, comprising:

a fluid circuit, the fluid circuit comprising:

a compressor;

a first heat exchanger;

an expander; and

a second heat exchanger;

2. The HVACR system of claim 1, further comprising a first pressure sensor configured to measure pressure at the dynamic receiver and a second pressure sensor configured to measure pressure between the expander and the second heat exchanger.

3. The HVACR system of claim 2, wherein the controller is configured to determine the mass flow through the outlet valve based on a difference between a first pressure reading from the first pressure sensor and a second pressure reading from the second pressure sensor.

4. The HVACR system of claim 1, wherein the controller is configured to determine a desired total mass flow, and wherein controlling the expander based on flow through the outlet valve comprises controlling the expander such that a sum of mass flow through the outlet valve and mass flow through the expander is equal to the desired total mass flow.

5. The HVACR system of claim 1, further comprising a four-way valve.

6. The HVACR system of claim 5, further comprising a third heat exchanger, and wherein the first heat exchanger is configured to exchange heat between a working fluid in the fluid loop and a first process fluid, the second heat exchanger is configured to exchange heat between the working fluid and a second process fluid, and the third heat exchanger is configured to exchange heat with ambient air.

7. A method of controlling a heating, ventilation, air conditioning and refrigeration (HVACR) system, the system comprising: a circuit comprising an expander, a dynamic receiver in parallel with the expander, and an outlet valve configured to control flow from the dynamic receiver to the circuit, the method comprising:

determining a mass flow rate through the outlet valve and; and

8. The method of claim 7, further comprising receiving a first pressure measurement from a first pressure sensor configured to measure a pressure at the dynamic receiver and a second pressure measurement from a second pressure sensor configured to measure a pressure downstream of the expander, and wherein determining the mass flow through the outlet valve is based on a difference between the first pressure and the second pressure.

9. The method of claim 7, further comprising determining a desired total mass flow.

10. The method of claim 9, wherein controlling the outlet valve comprises controlling a mass flow through the expander such that a sum of the mass flow through the outlet valve and the mass flow through the expander is equal to the desired total mass flow.