EP4728227A1

EP4728227A1 - Evaporator and integrated accumulator and subcooler for hvac&r system

Info

Publication number: EP4728227A1
Application number: EP24824234.9A
Authority: EP
Inventors: Jing Li; Xingshun GAO; Austin RETH
Original assignee: Tyco Fire and Security GmbH
Current assignee: Tyco Fire and Security GmbH
Priority date: 2023-06-15
Filing date: 2024-06-14
Publication date: 2026-04-22
Also published as: WO2024259247A1; CN121620674A

Abstract

A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a working fluid circuit configured to circulate a working fluid therethrough, an evaporator disposed along the working fluid circuit, where the evaporator is configured to place the working fluid in a heat exchange relationship with a conditioning fluid, and a vessel disposed along the working fluid circuit, where the vessel includes an accumulator section and a subcooling section. The working fluid circuit is configured to direct a first flow of the working fluid from the evaporator to the accumulator section of the vessel, the accumulator section is configured to separate the first flow of working fluid into a vapor working fluid and a liquid working fluid, the vessel is configured to direct the liquid working fluid from the accumulator section to the subcooling section, and the subcooling section of the vessel is configured to place the liquid working fluid in a heat exchange relationship with a second flow of working fluid received via the working fluid circuit.

Description

EVAPORATOR AND INTEGRATED ACCUMULATOR AND SUBCOOLER FOR HVAC&R SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from and the benefit of U.S. Provisional Patent Application No. 63/521,301, entitled “INTEGRATED ACCUMULATOR AND SUBCOOLER,’' filed June 15, 2023, which is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

[0002] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0003] Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems, such as chiller systems and/or other vapor compression systems, utilize a working fluid (e.g., a refrigerant) that changes phases between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures within components of the HVAC&R system. The HVAC&R system may include a working fluid circuit having one or more heat exchangers configured to place the working fluid in a heat exchange relationship with an additional fluid (e g., cooling fluid, conditioning fluid, water) in order to condition (e.g., heat and/or cool) the additional fluid. The HVAC&R system may deliver the additional fluid to conditioning equipment and/or a conditioned environment serviced by the HVAC&R system. In such applications, the additional fluid may be directed through downstream equipment, such as air handlers, to condition other fluids, such as air in a building.

[0004] Unfortunately, existing HVAC&R systems ty pically utilize heat exchangers that are susceptible to various drawbacks. For example, existing heat exchangers in HVAC&R systems may induce undesired flow restrictions, such as pressure drop, in fluids directed therethrough, may have configurations, materials, and/or designs that are costly, may be susceptible to other inefficiencies, such as uneven fluid distribution and/or heat transfer rates, and/or may not operate efficiently with certain types of working fluids. For example, existing heat exchangers may not provide a desired operating capacity of the HVAC&R system with certain types of working fluids. Accordingly, improved HVAC&R systems and heat exchangers are desired.

SUMMARY

[0005] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0006] In an embodiment of the present disclosure, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a working fluid circuit configured to circulate a working fluid therethrough, an evaporator disposed along the working fluid circuit, where the evaporator is configured to place the working fluid in a heat exchange relationship with a conditioning fluid, and a vessel disposed along the working fluid circuit, where the vessel includes an accumulator section and a subcooling section. The working fluid circuit is configured to direct a first flow of the working fluid from the evaporator to the accumulator section of the vessel, the accumulator section is configured to separate the first flow of the working fluid into a vapor working fluid and a liquid working fluid, the vessel is configured to direct the liquid working fluid from the accumulator section to the subcooling section, and the subcooling section of the vessel is configured to place the liquid working fluid in a heat exchange relationship with a second flow of the working fluid received via the working fluid circuit.

[0007] In another embodiment of the present disclosure, a chiller system of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a working fluid circuit configured to circulate a working fluid therethrough and a vessel disposed along the working fluid circuit, where the vessel includes an accumulator portion configured to receive a first flow of the working fluid and separate the first flow of the working fluid into vapor working fluid and liquid working fluid. The chiller system further includes an evaporator disposed along the working fluid circuit. The evaporator includes a brazed plate heat exchanger configured to place the working fluid in a heat exchange relationship with a flow of conditioning fluid, the brazed plate heat exchanger is configured to discharge a biphasic flow of the working fluid, and the working fluid circuit is configured to direct the biphasic flow of the working fluid from the evaporator to the accumulator portion of the vessel as the first flow of working fluid.

[0008] In a further embodiment of the present disclosure, a chiller system of heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes an evaporator disposed along a working fluid circuit, where the evaporator is configured to place a first flow of working fluid in a heat exchange relationship with a flow of conditioning fluid, the evaporator is a brazed plate heat exchanger, and the brazed plate heat exchanger is configured to discharge a biphasic flow of the working fluid. The chiller system also includes an integrated accumulator and subcooler unit disposed along the working fluid circuit. The integrated accumulator and subcooler unit includes a housing and an accumulator portion disposed within the housing. The accumulator portion is configured to receive the biphasic flow of the working fluid from the brazed plate heat exchanger, the accumulator portion is configured to configured to separate the biphasic flow of the working fluid into vapor working fluid and liquid working fluid, and the accumulator portion is configured to discharge the vapor working fluid from the housing. The integrated accumulator and subcooler unit also includes a subcooler portion disposed within the housing. The subcooler portion is configured to receive the liquid working fluid from the accumulator portion and place the liquid working fluid in a heat exchange relationship with a second flow of the working fluid received from a condenser of the working fluid circuit to vaporize the liquid working fluid and subcool the second flow of the working fluid. BRIEF DESCRIPTION OF THE FIGURES

[0009] Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

[0010] FIG. 1 is a perspective view of an embodiment of a building that may utilize a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0011] FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0012] FIG. 3 is a schematic of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0013] FIG. 4 is a schematic of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0014] FIG. 5 is a schematic of an embodiment of a vapor compression system, illustrating two working fluid circuits, each including an integrated accumulator and subcooler, in accordance with an aspect of the present disclosure;

[0015] FIG. 6 is a schematic of an embodiment of a portion of an HVAC&R system, illustrating two heat exchangers configured as brazed plate heat exchangers arranged in series relative to a flow of conditioning fluid directed therethrough, in accordance with an aspect of the present disclosure;

[0016] FIG. 7 is a schematic of an embodiment of a portion of an HVAC&R system, illustrating an integrated accumulator and subcooler and a lubricant return system for compressors of the vapor compression system, in accordance with an aspect of the present disclosure;

[0017] FIG. 8 is a schematic of an embodiment of an integrated accumulator and subcooler of an HVAC&R system, in accordance with an aspect of the present disclosure; [0018] FIG. 9 is a schematic of an embodiment of a portion of the integrated accumulator and subcooler of FIG. 8, in accordance with an aspect of the present disclosure;

[0019] FIG. 10 is a schematic axial view of an embodiment of an integrated accumulator and subcooler of an HVAC&R system, in accordance with an aspect of the present disclosure;

[0020] FIG. 11 is a schematic side view of an embodiment of the integrated accumulator and subcooler of FIG. 10, in accordance with an aspect of the present disclosure; and

[0021] FIG. 12 is a schematic top view of an embodiment of a portion of the integrated accumulator and subcooler of FIG. 10, in accordance with an aspect of the present disclosure.

DETAILED DESCRIPTION

[0022] One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementationspecific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0023] When introducing elements of various embodiments of the present disclosure, the articles “a,” "an." and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including.” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0024] As used herein, the terms "‘approximately,” “generally,” and “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to mean that the property value may be within +/- 5%, within +/- 4%, within +/- 3%, within +/- 2%, within +/- 1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to mean that the given feature is within +/- 5%, within +/- 4%, within +/- 3%, within +/- 2%, within +/- 1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Further, it should be understood that mathematical terms, such as “planar,” “slope,” “perpendicular,” “parallel,” and so forth are intended to encompass features of surfaces or elements as understood to one of ordinary skill in the relevant art, and should not be rigidly interpreted as might be understood in the mathematical arts. For example, a “planar” surface is intended to encompass a surface that is machined, molded, or otherwise formed to be substantially flat or smooth (within related tolerances) using techniques and tools available to one of ordinary skill in the art. Similarly, a surface having a “slope” is intended to encompass a surface that is machined, molded, or otherwise formed to be oriented at an angle (e.g., incline) with respect to a point of reference using techniques and tools available to one of ordinary skill in the art.

[0025] As mentioned above, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system may be used to thermally regulate a space within a building, home, or other suitable structure. For example, the HVAC&R system may include a vapor compression system (e.g., a chiller system, heat pump system) configured to transfer thermal energy between a working fluid (e.g.. refrigerant, heat transfer fluid) and a fluid to be conditioned (e.g., air. water, or brine). The vapor compression system may include a working fluid circuit (e.g., vapor compression circuit) that includes one or more heat exchangers (e.g., a condenser and an evaporator) that are fluidly coupled to one another via one or more conduits. The one or more heat exchangers are each configured to place the working fluid in a heat exchange relationship with another fluid, such as the fluid to be conditioned, a cooling fluid, another portion of the working fluid circulated through the working fluid circuit, another suitable fluid, or any combination thereof.

[0026] Unfortunately, existing HVAC&R systems and heat exchangers are susceptible to various drawbacks. For example, certain heat exchangers may induce undesired pressure drops in fluids directed therethrough, may have configurations, materials, and/or designs that are costly, may be susceptible to uneven fluid distribution and/or heat transfer inefficiencies, and/or may not operate efficiently with certain types of working fluids. For example, existing heat exchangers utilized in HVAC&R systems may operate inefficiently with low-pressure working fluids and medium-pressure working fluids with low global warming potential (GWP). Existing HVAC&R systems are also susceptible to other deficiencies, such as high costs associated with manufacture, assembly, and operation, undesired mixing of lubricant and working fluid, utilization of working fluids with undesired GWP, and limited operating capacities.

[0027] Accordingly, present embodiments are directed to HVAC&R systems configured to mitigate one or more of the drawbacks discussed above. For example, the present techniques include utilization of a brazed plate heat exchanger (BPHE) as an evaporator in an HVAC&R system, such as an air-cooled chiller and/or a water- cooled chiller. As discussed in further detail below, the BPHE may enable use of working fluids, such as medium-pressure working fluids and/or low-pressure working fluids, having low GWP in the HVCA&R system. The BPHE may further enable operation of the HVAC&R system with the medium-pressure working fluid and/or low-pressure working fluid at improved operating capacities, improved efficiencies, or both, while also reducing costs associated with manufacture, assembly, and/or operation of the HVAC&R system. In this way, HVAC&R systems incorporating the present techniques may operate with reduce greenhouse gas emissions and/or reduced energy consumption. [0028] Present embodiments also include an integrated or combined accumulator and subcooler in an HVAC&R system. The integrated accumulator and subcooler may be disposed along a working fluid circuit of the HVAC&R system and may provide various advantageous benefits. For example, the integrated accumulator and subcooler may enable subcooling of working fluid discharged by a condenser of the working fluid circuit, as well separation of liquid working fluid and vapor working fluid discharged from an evaporator of the working fluid circuit and prior to conveyance of the working fluid to a compressor of the working fluid circuit. The integrated accumulator and subcooler may also enable improved separation of lubricant (e.g., oil) and working fluid from one another to enable improved lubrication of rotating components (e.g., compressor components) during operation of the HVAC&R system. Details of the foregoing features and benefits in accordance with the present techniques are described further throughout the following disclosure. It should be noted that present embodiments may also include an embodiment wherein the integrated accumulator and subcooler are split into two sections (e.g., an accumulator and a subcooler) used to purify oil and produce extra subcooling.

[0029] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of a heating, ventilating, air conditioning, and/or refrigeration (HVAC&R) system 10 in a building 12 for a typical commercial setting. The HVAC&R system 10 may include a vapor compression system 14 (e.g., a chiller, water-cooled chiller, air-cooled chiller) configured to supply a chilled liquid (e.g., a conditioning fluid), which may be used to cool the building 12. The HVAC&R system 10 may also include a boiler 16 configured to supply a warm liquid to heat the building 12. The vapor compression system 14, also referred to herein as a chiller, may circulate a working fluid (e.g., refrigerant) that is cooled by a cooling fluid (e.g.. a liquid, such as water) in a condenser of the vapor compression system 14, and that is heated by a conditioning fluid (e.g., a liquid, such as water) in an evaporator of the vapor compression system 14. In some embodiments, the cooling fluid may be provided by a cooling tower which cools the cooling fluid via, for example, heat transfer with ambient air. The conditioning fluid, cooled by the working fluid as noted above, may be utilized to cool an air flow provided to conditioned spaces of the building 12. [0030] The HVAC&R system 10 may also include an air distribution system which circulates air through the building 12. The air distribution system may include an air return duct 18, an air supply duct 20, and/or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger that is connected to the boiler 16 and the vapor compression system 14 by conduits 24. The heat exchanger in the air handler 22 may receive either heated liquid from the boiler 16 or the conditioning fluid (e.g., chilled liquid, such as water) from the vapor compression system 14, depending on the mode of operation of the HVAC&R system 10. The HVAC&R system 10 is shown with a separate air handler on each floor of the building 12, but in other embodiments, the HVAC&R system 10 may include air handlers 22 and/or other components that may be shared between or among floors.

[0031] FIGS. 2 and 3 are schematics of embodiments of the vapor compression system 14 (e.g., chiller, chiller system) that may be used in the HVAC&R system 10. The vapor compression system 14 may circulate a working fluid (e.g., a refrigerant) through a circuit (e.g., working fluid circuit, refrigerant circuit) starting with a compressor 32, such as a centrifugal compressor. The circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and an evaporator 38 (e.g., a liquid chiller). The vapor compression system 14 may further include a control panel 40 that has an analog to digital (A/D) converter 42, a microprocessor 44, a nonvolatile memory 46, and/or an interface board 48.

[0032] Some examples of fluids that may be used as working fluids (e.g., refrigerants) in the vapor compression system 14 are hydrofluorocarbon (HFC) based working fluids, for example, R-134a, hydrofluoro olefin (HFO), “natural" working fluids like ammonia (NH3). R-717, carbon dioxide (CO2). R-744. or hydrocarbonbased working fluids, water vapor, medium-pressure working fluids, low-pressure working fluids, or any other suitable working fluid. Other examples of working fluids that may be circulated through the vapor compression system 14 include R-123. R- 514A, R-1224yd, R-1233zd, R-134a. R-1234ze. R-1234yf. R-1311, and R-32. In some embodiments, the vapor compression system 14 may be configured to efficiently utilize working fluids having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere of pressure, also referred to as low pressure working fluids, versus a medium pressure working fluid, such as R-134a. As used herein, ‘'normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure.

[0033] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSDs) 52, a motor 50, the compressor 32, the condenser 34, the expansion valve or device 36, and/or the evaporator 38. The motor 50 may drive the compressor 32 and may be powered by the VSD 52. The VSD 52 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be powered directly from an AC or direct current (DC) power source. The motor 50 may include any type of motor (e.g., electric motor) that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

[0034] The compressor 32 compresses a working fluid vapor and delivers the vapor to the condenser 34 through a discharge passage. In some embodiments, the compressor 32 may be a centrifugal compressor. The working fluid vapor delivered by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. The working fluid vapor may condense to a working fluid liquid in the condenser 34 due to thermal heat transfer with the cooling fluid. The liquid working fluid from the condenser 34 may flow through the expansion device 36 and to the evaporator 38. In the illustrated embodiment of FIG. 3, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies the cooling fluid to the condenser 34.

[0035] The liquid working fluid delivered to the evaporator 38 may absorb heat from a conditioning fluid, which may or may not be the same cooling fluid used in the condenser 34. For example, the conditioning fluid may be cooled by the working fluid in the evaporator 38, and then the conditioning fluid may be utilized in the building 12 to condition (e.g., cool) an air flow provided to condition a space in the building 12. The liquid working fluid in the evaporator 38 may undergo a phase change from the liquid working fluid to a working fluid vapor. As shown in the illustrated embodiment of FIG. 3, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to a load 62 (e.g., a cooling load). The conditioning fluid of the evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via the return line 60R and exits the evaporator 38 via the supply line 60S. The evaporator 38 may reduce the temperature of the conditioning fluid in the tube bundle 58 via thermal heat transfer with the working fluid. The tube bundle 58 in the evaporator 38 may include a plurality of tubes and/or a plurality of tube bundles. In any case, the vapor working fluid exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

[0036] FIG. 4 is a schematic of an embodiment of the vapor compression system 14 with an intermediate circuit 64 incorporated between the condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly coupled to the condenser 34. As shown in the illustrated embodiment of FIG. 4, the inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler, an economizer, etc.). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or a "surface economizer." In the illustrated embodiment of FIG. 4, the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to lower the pressure of (e.g., expand) the liquid working fluid received from the condenser 34. During the expansion process, a portion of the liquid working fluid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor working fluid from the liquid working fluid received from the first expansion device 66.

[0037] Additionally, the intermediate vessel 70 may provide for further expansion of the liquid working fluid due to a pressure drop experienced by the liquid working fluid when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor working fluid in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32. In other embodiments, the vapor working fluid in the intermediate vessel 70 may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage). The liquid working fluid that collects in the intermediate vessel 70 may be at a lower enthalpy than the liquid working fluid exiting the condenser 34 due to expansion of the working fluid at the expansion device 66 and/or in the intermediate vessel 70. The liquid working fluid from intermediate vessel 70 may then flow through line 72 and through a second expansion device 36 to the evaporator 38.

[0038] It should be appreciated that any of the features described herein may be incorporated with the vapor compression system 14 or any other suitable HVAC&R systems. For example, the present techniques may be incorporated with any suitable HVAC&R system having a first heat exchanger (e.g., an evaporator) and a second heat exchanger (e.g., condenser) fluidly coupled to one another along a vapor compression circuit. In some embodiments, the present techniques may be incorporated with a chiller system, such as an air-cooled chiller system or a water- cooled chiller system. However, it should be appreciated that the present techniques may also be implemented with other types and configurations of HVAC&R systems configured to circulate a working fluid therethrough.

[0039] As discussed above, present embodiments are directed to HVAC&R systems configured to circulate medium-pressure and/or low-pressure working fluids along a working fluid circuit and through one or more heat exchangers to enable transfer of heat (e.g., thermal energy) between the working fluid and one or more additional fluids (e.g., water, air, brine, etc.). For example, an HVAC&R system may include one or more evaporators configured as a brazed plate heat exchanger (BPHE) configured to direct a medium-pressure and/or low-pressure working fluid therethrough. In particular, the working fluid may be directed through the BPHE in a liquid or substantially liquid phase to enable improved transfer of heat between the working fluid and another fluid, while also enabling flow of the working fluid through the BPHE with a reduced pressure drop of the working fluid.

[0040] Additionally, present techniques include implementation of an accumulator and a subcooler as an integrated or combined unit (e.g., vessel) along the working fluid circuit of the HVAC&R system. The integrated accumulator and subcooler may enable subcooling of working fluid discharged by a condenser of the working fluid circuit, as well separation of liquid working fluid and vapor working fluid discharged from an evaporator (e.g., BPHE) of the working fluid circuit and prior to conveyance of the working fluid to a compressor of the working fluid circuit. Moreover, the integrated accumulator and subcooler is configured to enable improved separation of lubricant (e.g., oil) and working fluid from one another and thereby enable improved supply of lubricant to rotating components (e.g., compressor components) of the HVAC&R system. It should be appreciated that any of the features described below may be implemented alone in an HVAC&R system or in any suitable combination with one another.

[0041] With the foregoing in mind, FIG. 5 is a schematic of an embodiment of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system 100 (e.g., vapor compression system), in accordance with present techniques. For example, the HVAC&R system 100 may be an air-cooled chiller (e.g.. chiller system). Other embodiments of the HVAC&R system 100 may be configured as a water-cooled chiller system, and it should be appreciated that various embodiments of the HVAC&R system 100 may have any suitable configuration and may incorporate one or more of the features and/or systems described herein.

[0042] In the illustrated embodiment, the HVAC&R system 100 includes a first working fluid circuit 102 (e.g., first vapor compression system, first vapor compression circuit) and a second working fluid circuit 104 (e.g.. second vapor compression system, second vapor compression circuit). In other embodiments, the HVAC&R system 100 may include one working fluid circuit or more than two working fluid circuits having any of the features described herein. The HVAC&R system 100 also includes a condenser system 106 (e.g., condenser) having a plurality of condenser coils 108 (e.g.. heat exchanger slabs, heat exchangers). The condenser system 106 includes a plurality of fans 110 configured to direct an air flow 112 (e.g., ambient air) across the condenser coils 108 to enable transfer of heat between the air flow 112 and a working fluid directed through the condenser coils 108. In some embodiments, the condenser coils 108 may be disposed along the first working fluid circuit 102 and the second working fluid circuit 104. In other words, the condenser system 106 (e.g., condenser coils 108) may be common to both the first working fluid circuit 102 and the second working fluid circuit 104, and the first working fluid circuit 102 and the second working fluid circuit 104 may circulate a working fluid (e.g., the same working fluid) therethrough. In such embodiments, one or more conduits and/or working fluid flow paths may be shared and/or common to both the first working fluid circuit 102 and the second working fluid circuit 104. Alternatively, the first working fluid circuit 102 and the second working fluid circuit 104 may be fluidly separate from one another (e.g., with respect to working fluid flow) and may circulate separate (e.g., different) flows of working fluid therethrough. In such embodiments, a first portion or number of the condenser coils 108 may be disposed along the first working fluid circuit 102, and a second portion or number of the condenser coils 108 (e.g., distinct from the first portion or number of condenser coils 108) may be disposed along the second working fluid circuit 104.

[0043] The first working fluid circuit 102 also includes a first evaporator 114, a first compressor system 116 (e.g., one or more compressors), and a first expansion valve 118 (e.g., electronic expansion valve [EEV]). The first compressor system 116 may include any suitable number, type, and/or configuration of compressors. The illustrated embodiment of the first compressor system 116 includes a first compressor 120 and a second compressor 122 arranged in parallel with one another (e.g., relative to flow of working fluid along the first working fluid circuit 102), but other embodiments of the first compressor system 116 may include a single compressor or more than two compressors, which may be arranged in parallel or in series relative to flow of working fluid along the first working fluid circuit 102. The compressors of the first compressor system 116 may be any suitable type of compressor, such as centrifugal compressors, scroll compressors, screw compressors, another type of positive displacement compressor, and so forth. The compressors of the first compressor system 116 may be fixed speed compressors, multi-stage compressors, variable speed compressors, or any combination thereof. The first working fluid circuit 102 also includes a first accumulator 124 (e.g., accumulator portion, accumulator section) and a first subcooler 126 (e.g., subcooler portion, subcooling section). The first accumulator 124 and the first subcooler 126 are configured (e.g., assembled, arranged) as a first integrated unit 128 (e.g., assembly, vessel) disposed along the first working fluid circuit 102. Details of the first accumulator 124 and the first subcooler 126 integrated with one another are described further below. [0044] Similar to the first working fluid circuit 102, the second working fluid circuit 104 (e.g., additional working fluid circuit) includes a second evaporator 130 (e.g., additional evaporator), a second compressor system 132 (e.g., one or more compressors), and a second expansion valve 134 (e.g.. electronic expansion valve [EEV]). The second compressor system 132 includes a first compressor 136 (e.g., first additional compressor) and a second compressor 138 (e.g., second additional compressor), but other embodiments may have any suitable number of compressors, such as one, three, four, or more compressors. As similarly discussed above, the second compressor system 132 may include one or more centrifugal compressors, scroll compressors, screw compressors, another type of positive displacement compressor, fixed speed compressors, multi-stage compressors, variable speed compressors, or any combination thereof, and the compressors of the second compressor system 132 may be arranged in series and/or in parallel with one another, relative to flow of working fluid along the second working fluid circuit 104. The second working fluid circuit 104 also includes a second accumulator 140 and a second subcooler 142 configured (e.g., assembled, arranged) as a second integrated unit 144 (e.g., assembly, vessel) disposed along the second working fluid circuit 104.

[0045] The first evaporator 114 of the first working fluid circuit 102 and the second evaporator 130 of the second working fluid circuit 104 are each configured to enable transfer of heat (e.g., thermal energy) between a working fluid and a conditioning fluid 146. For example, the conditioning fluid 146 may be water, brine, glycol, calcium chloride brine, ethylene glycol, sodium chloride brine, another suitable liquid, another type of fluid, or any combination thereof. As shown in the illustrated embodiment, the first evaporator 114 and the second evaporator 130 may be arranged in series with one another relative to flow of the conditioning fluid 146 therethrough. For example, the conditioning fluid 146 may first flow through the first evaporator 114 and may transfer heat with the working fluid (e.g., first working fluid) directed through the first evaporator 114. More specifically, heat may be transferred from the conditioning fluid 146 to the working fluid directed through the first evaporator 114 to cool the conditioning fluid 146 by a first amount or to a first degree (e.g., to a first temperature). Thereafter, the conditioning fluid 146 may be directed to flow through the second evaporator 130, whereby heat may be transferred from the conditioning fluid 146 to the working fluid directed through the second evaporator 130 to further cool the conditioning fluid 146 by a second (e.g., additional) amount or to a second (e.g., additional) extent (e.g., to a second temperature, lower than the first temperature). As similarly described above, the conditioning fluid 146 may be received from a cooling load (e.g., cooling load 62) and may be cooled by the first evaporator 114 and the second evaporator 130 before the conditioning fluid 146 is directed back to the cooling load to satisfy a demand of the cooling load (e.g., to condition air via air handling equipment).

[0046] In accordance with present techniques, the first evaporator 114, the second evaporator 130, or both may be configured as a brazed plate heat exchanger. That is, the first evaporator 114 may be a first brazed plate heat exchanger (BPHE) 148, and the second evaporator 130 may be a second brazed plate heat exchanger (BPHE) 150. Each BPHE 148, 150 may include a plurality of plates (e.g., corrugated plates) stacked and secured to one another to define a plurality of flow paths (e.g., channels) therebetween. The first BPHE 148 may receive the working fluid of the first working fluid circuit 102 and the conditioning fluid 146 and may direct the working fluid and the conditioning fluid 146 through alternating sets of flow paths between alternating plates of the first BPHE 148. In this way, heat may be transferred between the working fluid and the conditioning fluid 146 (e.g., via the plates of the first BPHE 148. The second BPHE 150 may have similar components and/or a similar configuration to enable heat exchange between the working fluid of the second working fluid circuit 104 and the conditioning fluid 146.

[0047] It is now recognized that implementation of the first BPHE 148 as the first evaporator 114 of the first working fluid circuit 102 and/or implementation of the second BPHE 150 as the second evaporator 130 of the second working fluid circuit 104 may enable improved operation of the HVAC&R system 100 and, more particularly, may enable improved operation of embodiments of the HVAC&R system 100 configured to utilize medium-pressure and/or low-pressure working fluids (e.g., low GWP working fluids) as the working fluids directed through the first working fluid circuit 102 and the second working fluid circuit 104. Thus, the present techniques enable improved operation of the HVAC&R system 100 while also reducing greenhouse gas emission and reducing power consumption. [0048] For example, the first BPHE 148 and the second BPHE 150 may induce reduced pressure drops in medium-pressure and/or low-pressure working fluids directed therethrough. To further reduce the pressure drop in the working fluid directed through the first evaporator 114 and/or the second evaporator 130, the first BPHE 148 and/or the second BPHE 150 may each be operated as a ‘'flooded” evaporator. That is, the first working fluid circuit 102, the second working fluid circuit 104, or both may be operated to cause the working fluid within the first BPHE 148 and/or the second BPHE 150 to be in a liquid phase or a substantially liquid phase as the working fluid is directed through, and discharged by. the first BPHE 148 and/or the second BPHE 150. Indeed, those skilled in the art will appreciate that a fluid in a liquid phase may experience reduced pressure drop as compared to a fluid in a gaseous or liquid phase. Furthermore, by operating the HVAC&R system 100 to direct the working fluid through (e.g.. completely through) the first BPHE 148 and/or the second BPHE 150 in a liquid or substantially liquid phase, the first BPHE 148 and/or the second BPHE 150 may also enable improved heat transfer (e.g., greater heat transfer rate, greater heat transfer surface area, enhanced heat transfer efficiency) between the working fluid and the conditioning fluid 146.

[0049] Operation of the first BPHE 148 (e.g., first evaporator 114) and the second BPHE 150 (e.g., second evaporator 130) as flooded evaporators also enables operation of the first working fluid circuit fO2 and the second working fluid circuit 104 at higher evaporating temperatures (e.g., higher suction evaporating temperatures). In this way, respective capacities of the first working fluid circuit 102 and the second working fluid circuit 104 may be increased. Additionally or alternatively, the first BPHE 148 and/or the second BPHE 150 may be implemented with a reduced size and nevertheless achieve a desired (e.g., increased) operating capacity and/or meet a particular demand of the HVAC&R system 100. In this way, costs associated with manufacture, assembly, operation, and/or maintenance of the first evaporator 114 and the second evaporator 130 may be reduced while meeting a desired capacity or demand of the HVAC&R system 100.

[0050] The following description continues with reference to the first working fluid circuit 102 and the components thereof. However, it should be appreciated that the second working fluid circuit 104 and the corresponding components thereof may be operated in a similar manner to achieve similar benefits and effects with the second working fluid circuit 104. As the first BPHE 148 (e.g., first evaporator 114) may be operated as a flooded evaporator configured to direct a liquid or substantially liquid working fluid therethrough, the first BPHE 148 may discharge a biphasic flow of the working fluid. That is, the working fluid discharged by the first BPHE 148 may be a two-phase mixture (e.g., a gas-liquid mixture, a vapor-liquid mixture) of working fluid. It will be appreciated that it is desirable to avoid conveyance of liquid working fluid from the first evaporator 114 to the first compressor system 116. Accordingly, the first working fluid circuit 102 is configured to separate the biphasic flow of working fluid discharged by the first evaporator 114 into vapor working fluid and liquid working fluid and to block flow of liquid working fluid to the first compressor system 116. To enable operation of the first working fluid circuit 102 in the manner described above and to provide the associated benefits and advantages (e.g., greater suction evaporating temperature, increased operating capacity, enhanced heat transfer efficiency, mitigation of liquid working fluid flow to the first compressor system 116, etc.), the first working fluid circuit 102 includes the first integrated unit 128 having the first accumulator 124 and the first subcooler 126. To further illustrate, operation of the first working fluid circuit 102 is described in further detail below.

[0051] The biphasic flow of working fluid discharged by the first evaporator 114 may be directed by the first working fluid circuit 102 to the first accumulator 124 of the first integrated unit 128. The first accumulator 124 may receive the biphasic flow of working fluid and may separate the biphasic flow of working fluid into vapor working fluid and liquid working fluid within the first accumulator 124. For example, the first accumulator 124 may operate or function as a flash tank and/or economizer. The vapor working fluid, separated from the liquid working fluid, may be discharged from the first accumulator 124, while the liquid working fluid in the first accumulator 124 may flow (e.g., via force of gravity, via centrifugal force) from the first accumulator 124 to the first subcooler 126 within the first integrated unit 128.

[0052] The first compressor system 116 may compress the vapor working fluid received from the first accumulator 124 and may direct the vapor working fluid along the first working fluid circuit 102 to the condenser system 106. Heat may be transferred from the vapor working fluid delivered to the air flow 112 (e.g., cooling fluid, ambient air flow) via the condenser system 106. The vapor working fluid may therefore condense to a liquid working fluid (e.g., high pressure liquid) at the condenser system 106. From the condenser system 106, the first working fluid circuit 102 may direct at least a portion of the condensed, liquid working fluid to the first subcooler 126 of the first integrated unit 128. In some embodiments, the first working fluid circuit 102 may include a first bypass conduit 152 configured to direct a portion of the condensed, liquid working fluid from the condenser system 106 to bypass the first subcooler 126 and flow directly toward the first expansion valve 118. Thus, in some embodiments, a first portion of the condensed, liquid working fluid may be directed along the first working fluid circuit 102 from the condenser system 106 to the first subcooler 126, and a second portion of the condensed, liquid working fluid may be directed along the first working fluid circuit 102 from the condenser system 106 to the first bypass conduit 152. In other embodiments, all or substantially all of the condensed working fluid may be directed from the condenser system 106 to the first subcooler 126.

[0053] As mentioned above, the first subcooler 126 is configured to receive liquid working fluid from the first accumulator 124 that is separated from vapor working fluid within the first accumulator 124. The first subcooler 126 also receives at least a portion of the condensed working fluid discharged from the condenser system 106. The first subcooler 126 is configured to place the liquid working fluid received from the first accumulator 124 in a heat exchange relationship with the condensed working fluid received from the condenser system 106. To this end, the first subcooler 126 may include one or more structures, components, and/or other features to enable transfer of heat between the liquid working fluid and the condensed working fluid. For example, the first subcooler 126 may include a cavity, basin, channel, or other volume configured to receive the liquid working fluid from the first accumulator 124, and the first subcooler 126 may include a conduit (e.g., tubing, subcooling conduit) fluidly coupled to the first working fluid circuit 102 and extending through the volume of the first subcooler 126 that is configured to direct the condensed working fluid therethrough. Thus, the liquid working fluid and the condensed working fluid may remain fluidly separated from one another within the first subcooler 126. [0054] The liquid working fluid may contact and/or be directed across the conduit to enable transfer of heat from the liquid working fluid to the condensed working fluid. It will be appreciated that the liquid working fluid received by the first subcooler 126 from the first accumulator 124 may have a temperature lower than that of the condensed working fluid received from the condenser system 106. Thus, heat may be transferred from the liquid working fluid to the condensed working fluid within the first subcooler 126 to subcool the condensed working fluid (e.g., to generate a subcooled working fluid). The condensed, subcooled working fluid may be discharged from the first subcooler 126 and directed through the first expansion valve 118, whereby the condensed, subcooled working fluid may be expanded to reduce a temperature and/or pressure of the working fluid before the working fluid is directed into the first evaporator 114 (e.g., first BPHE 148).

[0055] In some instances, the liquid working fluid separated from vapor working fluid in the first accumulator 124 may contain lubricant (e.g., oil) mixed therein. For example, lubricant may be utilized by the first compressor system 116 to enable desired operation of rotating components of the first compressor system 116. but an amount of lubricant may become entrained or mixed with the working fluid compressed by the first compressor system 116. Advantageously, operation of the first integrated unit 128 is configured to enable improved separation of the lubricant from the working fluid. For example, as the biphasic working fluid directed into the first accumulator 124 is separated into vapor working fluid and liquid working fluid, lubricant initially within the biphasic working fluid may remain with the liquid working fluid within the first accumulator 124 and may become separated from the vapor working fluid (e.g.. due to a weight or density of the lubricant). Thus, the liquid working fluid directed from the first accumulator 124 to the first subcooler 126 may have an increased concentration of lubricant.

[0056] As described above, within the first subcooler 126, heat may be transferred from the liquid working fluid to the condensed working fluid to subcool the condensed working fluid. As heat is transferred from the liquid working fluid, the liquid working fluid within the first subcooler 126 may vaporize within the first subcooler 126 and may be directed to flow out of the first subcooler 126 and out of the first integrated unit 128 to be directed toward the first compressor system 116 for compression and recirculation through the first working fluid circuit 102. As the liquid working fluid within the first subcooler 126 vaporizes, the working fluid may become separated from the lubricant within the first subcooler 126. That is, the lubricant within the liquid working fluid may not vaporize due to the transfer of heat from the liquid working fluid to the condensed working fluid. Instead, the lubricant may accumulate and/or become concentrated (e.g., purer) within the first subcooler 126.

[0057] In accordance with present techniques, the HVAC&R system 100 also includes a first lubricant return system 154 associated with the first working fluid circuit 102. The first lubricant return system 154 is configured to direct concentrated lubricant separated from working fluid within the first subcooler 126 to the first compressor system 116 for re-use to lubricant components (e.g. rotating components) of the first compressor system 116. In accordance with present techniques, the first lubricant return system 154 may be configured to separately direct respective flows of lubricant from the first subcooler 126 (e.g., first integrated unit 128) to each compressor of the first compressor system 116. For example, in the illustrated embodiment, the first lubricant return system 154 includes a first lubricant return conduit 156 (e.g., lubricant conduit) extending between the first subcooler 126 and the first compressor 120 (e.g., extending from the first subcooler 126 to the first compressor 120) and a second lubricant return conduit 158 (e.g.. lubricant conduit) extending between the first subcooler 126 and the second compressor 122 (e.g., extending from the first subcooler 126 to the second compressor 122). Thus, each compressor of the first compressor system 116 may include a dedicated lubricant return conduit configured to supply a high concentration of lubricant. To this end, each compressor of the first compressor system 116 may include a corresponding, respective oil sump. As a result, operation of one of the compressors of the first compressor system 116 may be suspended, while another of the compressors of the first compressor system 116 remains in operation, and the compressor that is in operation may continue to receive purified and/or concentrated oil separated from working fluid from the first subcooler 126 (e.g., first integrated unit 128). As discussed in further detail below, flow of the lubricant through the first lubricant return system 154 may be induced via a suction pressure and/or pressure differential across a respective suction conduit of a compressor that is in operation. Thus, lubricant may be supplied to operating compressors via the first lubricant return system 154 but may not be supplied to compressors that are not in operation, and lubricant may be supplied to the operating compressors without other components, such as pumps or valves, that would otherwise add costs and complexity to the HVAC&R system 100. Indeed, in the illustrated embodiment, the first lubricant return conduit 1 6 and the second lubricant return conduit 158 do not have to include a valve or a pump.

[0058] As mentioned above, the second working fluid circuit 104 having the second evaporator 130 (e.g., second BPHE 150) and the second integrated unit 144 with the second accumulator 140 and the second subcooler 142 may operate in a manner similar to that described above with regard to the first working fluid circuit 102. The second working fluid circuit 104 may also include corresponding components similar to those of the first working fluid circuit 102 described above. For example, the second working fluid circuit 104 may be configured to direct at least a portion of condensed working fluid from the condenser system 106 to the second subcooler 142, and the second working fluid circuit 104 may include a second bypass conduit 160 configured to direct a portion of condensed working fluid from the condenser system 106 to bypass the second subcooler 142 and flow directly toward the second expansion valve 134. In some embodiments, the HVAC&R system 100 may also include a second lubricant return system 162 associated with the second working fluid circuit 104. In particular, the second lubricant return system 162 may include a first lubricant return conduit 164 (e.g., a first additional lubricant return conduit) extending between the second subcooler 142 and the first compressor 136 (e.g., extending from the second subcooler 142 to the first compressor 136) of the second compressor system 132 and a second lubricant return conduit 166 (e.g., a second additional lubricant return conduit) extending between the second subcooler 142 and the second compressor 138 (e.g., extending from the second subcooler 142 to the second compressor 138) of the second compressor system 132. Thus, each compressor of the second compressor system 132 may include a dedicated lubricant return conduit configured to supply a high concentration of lubricant.

[0059] In some embodiments, the HVAC&R system 100 may include additional features or components configured to enable one or more of the operations and/or functionalities described herein. For example, the HVAC&R system 100 may include a controller 168 (e.g., automation controller, electronic controller, chiller controller) configured to control operation of one or more components of the HVAC&R system 100. The controller 168 may be configured to control operation of the first compressor system 116 (e.g., compressors 120, 122) , the second compressor system 132 (e.g., compressors 136, 138), the first expansion valve 118, the second expansion valve 134, one or more additional valves, the fans 110, another suitable component, or any combination thereof to enable any of the operations and/or functionalities described herein. The controller 168 may, for example, include the control panel 40 (e.g., chiller controller, main controller) described above.

[0060] In any case, the controller 168 (e.g., chiller controller, control system, control panel 40) includes processing circuitry 170. such as one or more microprocessors, which may execute software for controlling the components of the HVAC&R system 100 and/or components thereof. The processing circuitry 170 may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICS), or some combination thereof. For example, the processing circuitry 170 may include one or more reduced instruction set (RISC) processors, one or more complex instruction set computer (CISC) processors, one or more field programmable gate arrays (FPGA), one or more integrated circuits, one or more digital signal processors, and so forth.

[0061] The controller 168 may also include a memory 172 (e.g., a memory device) that may store information such as instructions (e.g., executable instructions, code, software logic), control software, look up tables, configuration data, etc. The memory 172 may include a volatile memory-. such as random access memory (RAM), and/or a nonvolatile memory⁷, such as read-only memoi ⁷ (ROM). The memory⁷ 172 may store a variety of information and may be used for various purposes. For example, the memory 172 may store processor-executable instructions including firmware or software for the processing circuitry 170 to execute, such as instructions for controlling components of the HVAC&R system 100, the first compressor system 116, the second compressor system 132, the condenser system 106, the first integrated unit 128, the second integrated unit 144. the first working fluid circuit 102. the second working fluid circuit 104, the first expansion valve 118, the second expansion valve 134, and so forth. In some embodiments, the memory' 172 is a tangible, non- transitory, machine-readable-medium that may store machine-readable instructions for the processing circuitry 170 to execute. The memory 172 may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The memory 172 may store data, instructions, and any other suitable data. It should be appreciated that the memory 172 may store processor-executable instructions (e.g.. for execution via the processing circuitry 170) to enable operation of any of the components described herein and to enable any of the functionalities and/or operations described herein.

[0062] The controller 168 may be configured to adjust operation of one or more components of the HVAC&R system 100 based on, or in response to, data and/or feedback received from one or more sensors 174. The sensors 174 are configured to detect various operating conditions and/or parameters associated with operation of the HVAC&R system 100. For example, one or more of the sensors 174 may be configured to detect a temperature of the working fluid, a pressure of the working fluid, a flow rate of the working fluid, a liquid level of the working fluid (e.g., within the first subcooler 126 and/or the second subcooler 142), an operating stage or speed of a compressor of the first compressor system 116 and/or the second compressor system 132, a temperature, pressure, and/or flow rate of the conditioning fluid 146, another suitable operating parameter, or any combination thereof.

[0063] FIG. 6 is a schematic of an embodiment of a portion of the HVAC&R system 100, illustrating the first evaporator 114 of the first working fluid circuit 102 and the second evaporator 130 of the second working fluid circuit 104. As similarly described above, the first evaporator 114 is configured as the first BPHE 148, and the second evaporator 130 is configured as the second BPHE 150. To this end, the first BPHE 148 includes a second plurality of plates 204 stacked with one another to define a second plurality of flow paths 206 (e.g.. channels, flow channels) therebetween.

[0064] As described above, the first BPHE 148 is configured to receive a first working fluid 208 directed through the first working fluid circuit 102 and to receive a flow of the conditioning fluid 146 (e.g., water). To this end, the first BPHE 148 includes a first working fluid inlet 210 configured to receive the first working fluid 208 from the first working fluid circuit 102 (e.g., the first expansion valve 118) and a first working fluid outlet 212 configured to discharge the first working fluid 208 from the first BPHE 148 (e.g., toward the first accumulator 124). The first BPHE 148 includes a first conditioning fluid inlet 214 configured to receive the flow of conditioning fluid 146 (e.g., from a cooling load) and a first conditioning fluid outlet 216 configured to discharge the flow of conditioning fluid 146. The first working fluid inlet 210 and the first conditioning fluid inlet 214 are configured to direct the first working fluid 208 and the conditioning fluid 146. respectively, to alternating flow paths of the plurality of flow paths 202. The first working fluid outlet 212 and the first conditioning fluid outlet 216 may similarly receive the first working fluid 208 and the conditioning fluid 146, respectively, from the alternating flow paths of the plurality of flow paths 202, such that the first working fluid 208 and the conditioning fluid 146 remain fluidly separate within the first BPHE 148. In some embodiments, the first working fluid inlet 210, the first working fluid outlet 212, the first conditioning fluid inlet 214, and the first conditioning fluid outlet 216 are formed in a common plate 218 of the plurality of plates 200.

[0065] The second BPHE 150 is configured to receive a second working fluid 220 directed through the second working fluid circuit 104 and to receive the flow of conditioning fluid 146 (e.g., water). To this end, the second BPHE 150 includes a second working fluid inlet 222 configured to receive the second working fluid 220 from the second working fluid circuit 104 (e.g., the second expansion valve 134) and a second working fluid outlet 224 configured to discharge the second working fluid 220 from the second BPHE 150 (e.g.. toward the second accumulator 140). The second BPHE 150 also includes a second conditioning fluid inlet 226 configured to receive the flow of conditioning fluid 146 (e.g., from the first conditioning fluid outlet 216 of the first BPHE 148) and a second conditioning fluid outlet 228 configured to discharge the flow of conditioning fluid 146 (e.g., back toward the cooling load). The second working fluid inlet 222 and the second conditioning fluid inlet 226 are configured to direct the second working fluid 220 and the conditioning fluid 146, respectively, to alternating flow paths of the plurality' of flow paths 206. The second working fluid outlet 224 and the second conditioning fluid outlet 228 may similarly receive the second working fluid 220 and the conditioning fluid 146, respectively, from the alternating flow paths of the plurality of flow paths 206, such that the second working fluid 220 and the conditioning fluid 146 remain fluidly separate within the second BPHE 150. In some embodiments, the second working fluid inlet 222, the second working fluid outlet 224. the second conditioning fluid inlet 226, and the second conditioning fluid outlet 228 are formed in a common plate 230 of the plurality of plates 204.

[0066] As previously described, the first BPHE 148 and the second BPHE 150 are disposed in a series arrangement relative to flow of the conditioning fluid 146 through the first BPHE 148 and the second BPHE 150. To this end, the HVAC&R system 100 may include a conditioning fluid circuit 232 (e.g., conduit, piping) configured to direct the conditioning fluid 146 sequentially through the first BPHE 148 and the second BPHE 150. For example, the conditioning fluid circuit 232 may direct the conditioning fluid 146 into the first conditioning fluid inlet 214 of the first BPHE 148 (e.g., from a cooling load), the conditioning fluid circuit 232 may fluidly couple the first conditioning fluid outlet 216 of the first BPHE 148 and the second conditioning fluid inlet 226 of the second BPHE 150 and may direct the conditioning fluid 146 from the first BPHE 148 to the second BPHE 150, and/or the conditioning fluid circuit 232 may direct the conditioning fluid 146 from the second conditioning fluid outlet 228 back to the cooling load.

[0067] The first BPHE 148 may cool the conditioning fluid 146, via the first working fluid 208, by a first amount (e.g., to a first temperature), and the second BPHE 150 may further cool the conditioning fluid 146, via the second working fluid 220, by a second amount (e.g., to a second temperature, lower than the first temperature). In this way. the first working fluid circuit 102 and the second working fluid circuit 104 may cooperatively operate to cool the conditioning fluid by a desired amount (e.g., to a desired temperature) while utilizing medium-pressure and/or low- pressure working fluids, in accordance with the present techniques.

[0068] FIG. 7 is a schematic of a portion of an embodiment of the HVAC&R system 100, illustrating a compressor system 250, an integrated accumulator and subcooler unit 252 (e.g., integrated vessel, vessel), and a lubricant return system 254, which may be implemented with a working fluid circuit, such as the first working fluid circuit 102 and/or the second working fluid circuit 104, of the HVAC&R system 100. For example, the compressor system 250 may be an embodiment of the first compressor system 116 or the second compressor system 132 discussed above. Similarly, the integrated accumulator and subcooler unit 252 may be an embodiment of the first integrated unit 128 or the second integrated unit 144 discussed above, and the lubricant return system 254 may be an embodiment of the first lubricant return system 154 or the second lubricant return system 162 discussed above. The integrated accumulator and subcooler unit 252 may also be referred to herein as an integrated unit.

[0069] The compressor system 250 includes a first compressor 256 and a second compressor 258, which may be disposed along a common working fluid circuit (e.g., in parallel with one another) of the HVAC&R system 100. In some embodiments, the first compressor 256 and the second compressor 258 may each be a scroll compressor, but in other embodiments the first compressor 256 and the second compressor 258 may be any other suitable types of compressor. As similarly described above, the integrated accumulator and subcooler unit 252 includes an accumulator 260 (e.g., accumulator portion, accumulator section) and a subcooler 262 (e.g., subcooling section, subcooling portion) disposed within a common vessel 264 (e.g., housing, shell, enclosure, etc.).

[0070] The integrated accumulator and subcooler unit 252 may operate in a similar manner to that of the first integrated unit 128 described above. Thus, vapor working fluid separated from liquid working fluid within the accumulator 260 may be directed to the first compressor 256 and the second compressor 258 for compression and conveyance along the working fluid circuit having the compressor system 250 and the integrated accumulator and subcooler unit 252. To this end. the HVAC&R system 100 (e.g., working fluid circuit) includes a first suction conduit 266 configured to direct vapor working fluid from the integrated unit 252 to a first suction port 268 of the first compressor 256 and a second suction conduit 270 configured to direct vapor working fluid from the integrated unit 252 to a second suction port 272 of the second compressor 258. As the liquid working fluid within the subcooler 262 of the integrated unit 252 vaporizes (e.g., via heat transfer with a flow of working fluid received from the condenser system 106), the vaporized working fluid may also be directed through the common vessel 264 and to the first compressor 256 and the second compressor 258 via the first suction conduit 266 and the second suction conduit 270, respectively. In this way, the integrated accumulator and subcooler unit 252 enables implementation of the first BPHE 148 and/or the second BPHE 150 as flooded evaporators configured to discharge biphasic working fluid and inhibits flow of liquid working fluid into the first compressor 256 and the second compressor 258.

[0071] The illustrated embodiment also includes the lubricant return system 254 configured to direct lubricant from the integrated unit 252 (e.g., the subcooler 262) to the compressor system 250 for lubrication of components of the compressor system 250. As discussed above, concentrated lubricant may accumulate within the subcooler 262 as liquid working fluid mixed with the lubricant is vaporized (e.g., via heat transfer with a flow of working fluid received from the condenser system 106). The lubricant return system 254 is configured to direct separate, individual flows of lubricant from the integrated unit 252 to the first compressor 256 and the second compressor 258. For example, the lubricant return system 254 may include a first lubricant return conduit 274 extending to a first lubricant port 276 of the first compressor 256 and a second lubricant return conduit 278 extending to a second lubricant port 280 of the second compressor 258. The first compressor 256 may include a first lubricant sump 282 configured to receive lubricant via the first lubricant return conduit 274, and the second compressor 258 may include a second lubricant sump 284 configured to receive lubricant via the second lubricant return conduit 278.

[0072] Flow of lubricant may be induced through the lubricant return system 254 via operation of the compressor system 250. For example, during operation of the first compressor 256, the first compressor 256 may generate or induce a pressure differential between the first compressor 256 and the integrated unit 252 (e.g., the common vessel 264) as the first compressor 256 draws vapor working fluid into a first shell 286 of the first compressor 256. The pressure differential may therefore induce flow of lubricant from the integrated unit 252 (e.g.. the subcooler 262), along the first lubricant return conduit 274, and into the first compressor 256 (e.g., the first shell 286, the first lubricant sump 282) via the first lubricant port 276. Operation of the second compressor 258 may similarly generate a pressure differential between the second compressor 258 and the integrated unit 252 (e.g.. the common vessel 264) as the second compressor 258 draws vapor working fluid into a second shell 288 of the second compressor 258, which may thereby induce flow of lubricant along the second lubricant return conduit 278, and into the second compressor 258 (e.g., the second shell 288, the second lubricant sump 284) via the second lubricant port 280. In this way, return flows of the lubricant to the first compressor 256 and the second compressor 258 may be induced and controlled via operation of the first compressor 256 and the second compressor 258 and without additional pumps and/or control valves disposed along the first lubricant return conduit 274 and the second lubricant return conduit 278. thereby reducing costs and simplifying operation of the HVAC&R system 100.

[0073] Further, individual, separate operation of the first compressor 256 and/or the second compressor 258 may induce flow of lubricant from the integrated unit 252 thereto without also inducing flow of lubricant to the other of the first compressor 256 and/or the second compressor 258. In this way, present embodiments enable improved balancing (e g., equalization) of lubricant between the first compressor 256 and the second compressor 258 based on an operational status (e.g., active operation, nonoperation) of the first compressor 256 and/or the second compressor 258. In other words, during suspended operation of the second compressor 258 and during active operation of the first compressor 256, for example, concentrated lubricant (e.g., generated via operation of the subcooler 262) may be drawn from the integrated unit 252 to the first compressor 256 with reduced contamination of the lubricant, thereby improving reliable operation of the HVAC&R system 100. In other words, the first compressor 256 and the second compressor 258 may not rely on a common lubricant return system and/or a common lubricant sump.

[0074] FIG. 8 is a schematic of an embodiment of an integrated accumulator and subcooler unit 300 having an accumulator portion 302 (e.g., accumulator, accumulator section) and a subcooler portion 304 (e.g., subcooler, subcooling section, heat exchanger, heat exchange portion, heat exchange section) disposed within a vessel 306 (e.g., common vessel, housing, enclosure, etc ). The integrated accumulator and subcooler unit 300 may be an embodiment of the first integrated unit 128, the second integrated unit 144, and/or the integrated accumulator and subcooler unit 252 discussed above. It should be appreciated that the integrated accumulator and subcooler unit 300 described below is an exemplary and/or configuration of one embodiment of the integrated accumulator and subcooler unit 300 and that other embodiments have may have any suitable components, arrangement, and/or configuration that enables the functionalities and operations described herein. Throughout the following discussion, the integrated accumulator and subcooler unit 300 and components thereof may be described with reference to a vertical axis or direction 308 (e.g., a longitudinal axis or direction), a lateral axis or direction 310 (e.g., a radial axis or direction), and a circumferential axis or direction 312.

[0075] As similarly described above, the accumulator portion 302 and the subcooler portion 304 are disposed within the vessel 306. In the illustrated embodiment, the vessel 306 extends generally along the vertical axis 308. For example, the vessel 306 may be a generally cylindrical housing or enclosure extending along the vertical axis 308 and in the circumferential direction 312, such that the accumulator portion 302 is disposed vertically above the subcooler portion 304 within the vessel 306. The integrated accumulator and subcooler unit 300 further includes a working fluid inlet 314 (e.g., inlet conduit) configured to direct a flow of working fluid into the vessel 306. The working fluid inlet 314 may be fluidly coupled (e.g., connected, attached) to a working fluid circuit (e.g., first working fluid circuit 102, second working fluid circuit 104) and may be configured to receive a biphasic flow (e.g., vapor and liquid mixture) of working fluid, as indicated by arrow 316, from an evaporator (e.g., BPHE) of the HVAC&R system 100, in accordance with the present techniques. In some instances the biphasic flow of working fluid may also include an amount of lubricant, as mentioned above.

[0076] The integrated accumulator and subcooler unit 300 further includes a canister 318 (e.g., shell, container, barrel, drum, sleeve) disposed within (e.g., laterally and/or radially within, internal to) the vessel 306 and extending along the vertical axis 308 and extending in the circumferential direction 312. As shown, the working fluid inlet 314 may be a conduit extending through the vessel 306 and into the canister 318. The canister 318 generally defines an internal volume 320 configured to receive the biphasic working fluid from the working fluid inlet 314 (e.g., inlet conduit). In the illustrated embodiment, the working fluid inlet 314 extends into the internal volume 320 (e.g., along a central axis of the integrated unit 300) toward the subcooler portion 304 (e.g., to a lower portion of the canister 318). As will be appreciated, the biphasic flow of working fluid directed into the internal volume 320 may undergo expansion due to a pressure drop experienced by the biphasic flow of working fluid upon entering the internal volume 320. In this way, the accumulator portion 302 may operate and/or function as a flash tank or economizer and may separate the biphasic flow of working fluid into vapor working fluid and liquid working fluid.

[0077] For example, upon entering the internal volume 320 the biphasic flow of working fluid may “flash’’ or separate into vapor working fluid (e.g., indicated by arrows 322) and liquid working fluid (e.g., indicated by arrows 324). Within the internal volume 320, the vapor working fluid may flow along the vertical axis 308 in a generally upward direction (e.g.. toward a top 326, cap. or lid of the vessel 306). The liquid working fluid separated from the vapor working fluid within the internal volume 320 may flow along the vertical axis 308 in a generally downward direction (e.g., via force of gravity). The canister 320 may define an opening 328 at a top (e.g., an open or uncovered top) of the canister 320 to enable flow of the vapor working fluid out of the internal volume 320 and into a passage 330 (e.g., annulus, space, vapor working fluid passage) formed between (e.g., relative to the lateral axis 310, in the circumferential direction 312, relative to the vertical axis 308) the canister 318 and the vessel 306.

[0078] The integrated accumulator and subcooler unit 300 includes a vapor working fluid outlet 332 (e.g., outlet, port) formed in and/or extending from the vessel 306. The vapor working fluid outlet 332 is also fluidly coupled to the passage 330 formed within the vessel 306 between the vessel 306 and the canister 318. Accordingly, vapor working fluid separated from liquid working fluid within the accumulator portion 302 may flow from the passage 330 and through the vapor working fluid outlet 332, as indicated by arrow 334. The vapor working fluid outlet 332 may be fluidly coupled to one or more suction conduits (e.g., first suction conduit 266, second suction conduit 270) extending to one or more compressors of the working fluid circuit having the integrated accumulator and subcooler unit 300. In some embodiments, the integrated accumulator and subcooler unit 300 may includes multiple vapor working fluid outlets 332, and each vapor working fluid outlet 332 may be fluidly coupled to a corresponding compressor of a compressor system (e.g., compressor system 250) having multiple compressors. In this way, the vapor working fluid may be discharged from the accumulator portion 302 and directed to one or more compressors for compression and circulation along the working fluid circuit.

[0079] Liquid working fluid separated from the vapor working fluid within the accumulator portion 302 (e.g., the internal volume 320) may flow toward a base 336 of the canister 318. The base 336 may also define an outlet 338 (e.g., liquid working fluid outlet) configured to direct the liquid working fluid from the accumulator portion 302 into the subcooler portion 304. In some embodiments, the base 336 may have a geometry, shape, or configuration that enables, facilitates, or promotes flow of the liquid working fluid through the outlet 338 and into the subcooler portion 304. For example, the base 336 may have an inverted frustum shape, as shown. It should be appreciated that any lubricant mixed with the biphasic working fluid received by the integrated unit 300 may not separate from the liquid working fluid within the accumulator portion 302 and instead may flow toward the subcooler portion 304 with the liquid working fluid.

[0080] In some embodiments, the integrated accumulator and subcooler unit 300 may include a fluid deflector 340 (e.g., baffle, plate, guide surface) disposed downstream of the working fluid inlet, relative to flow of the biphasic working fluid into the internal volume 320. As shown, the fluid deflector 340 may be disposed generally within (e.g., relative to the lateral axis 310, internal to) a geometry of the base 336, such as within the inverted frustum shape. The fluid deflector 340 may also be disposed upstream of the outlet 338 formed via the base 336, relative to flow of the liquid working fluid from the accumulator portion 302 to the subcooler portion 304. In some applications, the fluid deflector 340 may be implemented to reduce turbulent flow of the liquid working fluid directed into the subcooler portion 304 and/or accumulated within the subcooler portion 304, as described further below.

[0081] Liquid working fluid directed through the outlet 338 and into the subcooler portion 304 may initially flow into a cavity 342 (e.g., central cavity, basin, liquid collection portion) of the subcooler portion 304. As described above, the subcooler portion 304 is configured to place the liquid working fluid in a heat exchange relationship with another flow of the working fluid directed along the working fluid circuit having the integrated accumulator and subcooler unit 300. Specifically, the subcooler portion 304 is configured to enable transfer of heat from a flow of condensed working fluid directed to the subcooler portion 304 from a condenser (e.g., condenser system 106) of the working fluid circuit to the liquid working fluid. To this end, the subcooler portion 304 may include any suitable number, type, and/or combination heat exchange components configured to establish the heat exchange relationship between the liquid working fluid received from the accumulator portion 302 and the condensed working fluid while maintaining fluid separation therebetween.

[0082] In the manner described above, the flow of condensed working fluid may be subcooled and/or further subcooled before the condensed working fluid is directed to an expansion valve and the evaporator (e.g. BPHE) of the working fluid circuit. As will be appreciated, subcooling and/or further subcooling of the condensed working fluid in this manner may enable an increased operating capacity of the HVAC&R system 100. Additionally, transfer of heat from the condensed working fluid to the liquid working fluid within the subcooler portion 304 may cause the liquid working fluid to vaporize, as discussed further below. As the liquid working fluid within the subcooler portion 304 vaporizes, lubricant mixed with the liquid working fluid may be separated from the vaporized working fluid and may remain within the subcooler portion 304. In this way, the integrated accumulator and subcooler unit 300 may also operate to remove working fluid from the lubricant and provide a purer and/or more concentrated flow of lubricant for use in lubricating components of the compressor system.

[0083] In the illustrated embodiment, the subcooler portion 304 includes one or more walls 344 (e g., partitions, dividers, extensions, panels) extending from a base 346 of the vessel 306 in a generally upward direction along the vertical axis 308. The one or more walls 344 form one or more channels 348 extending between the one or more walls 344. The walls 344 may have any suitable number, shape, arrangement, and/or configuration to define the one or more channels 348. For example, in some embodiments, the one or more walls 344 may have a generally curved (e.g., spiral) shape and/or arrangement to define a flow path (e g., spiral flow path) extending along the one or more channels 348, extending at least partially about the cavity 342 in the circumferential direction 312, and extending from the cavity 342 toward a wall

350 (e.g. outer wall, inner circumferential wall, inner surface) of the vessel 306.

[0084] As will be appreciated, the cavity 342 formed generally at a center of the subcooler portion 304 may be fluidly coupled to the one or more channels 348 (e.g., via an opening in one or more of the walls 344, a separation of two or more walls 344, below the outlet 338 relative to the vertical axis 308, etc.) to enable flow of the liquid working fluid into the channels 348, as indicated by arrows 352. It should be appreciated that the channels 348 may define a flow path of the liquid working fluid having any suitable shape or configuration. In some embodiments, one or more of the walls 344 and/or portions thereof (e.g., proximate the cavity 342, relative to the lateral axis 310) may be coupled to and/or fixed to the base 336 of the canister 318 to cover and retain the liquid working fluid and/or vaporized working within the channels 348 along at least a portion of the channels 348. As discussed further below, one or more of the walls 344 and/or portions thereof (e.g., proximate the wall 350 of the vessel 306 relative to the lateral axis 310) may be not be attached to the base 336 of the canister 318 to enable flow of vaporized working fluid toward the vapor working fluid outlet 332 (e.g., via the passage 330).

[0085] The subcooler portion 304 also includes features configured to enable flow of condensed working fluid (e.g.. received from the condenser system 106) through the subcooler portion 304. For example, the subcooler portion 304 includes one or more tubes 354 (e.g., conduits, pipes, coils) extending within the subcooler portion 304 and along the one or more channels 348 defining the flow path of the liquid working fluid. Thus, in some embodiments, the one or more tubes 354 may extend about the cavity 342 within the subcooler portion 304. The one or more tubes 354 may be fluidly coupled to an inlet manifold 356 (e g., inlet header) and an outlet manifold 358 (e.g., outlet header). The inlet manifold 356 may be fluidly coupled to the working fluid circuit and may be configured to receive the condensed working fluid from the condenser system 106 and to direct the condensed working fluid into the tubes 354. After the condensed working fluid flows through the tubes 354 and transfers heat to the liquid working fluid flowing within the channels 348 (e.g., to become subcooled), the condensed, subcooled working fluid may flow into the outlet manifold 358. The outlet manifold 358 may also be fluidly coupled to the working fluid circuit and may direct the condensed, subcooled working fluid into the working fluid circuit to flow toward an expansion valve (e.g., expansion valve 118, 134) of the working fluid circuit. In some embodiments, the inlet manifold 356 and/or the outlet manifold 358 may extend through the base 346 of the vessel 306 and may be at least partially disposed within the cavity 342 formed within the subcooler portion 304 and may extend at least partially along the vertical axis 308. Thus, the tubes 354 may extend from the cavity 342, along the channels 348 toward the wall 350 of the vessel 306, and back toward the cavity 342. Accordingly, in some embodiments, the one or more tubes 354 may be layered within the channels 348 to enable flow of the condensed working fluid from the cavity 342, toward the wall 350 and back toward the cavity 342.

[0086] As discussed above, the liquid working fluid flowing within the channels 348 may absorb heat from the condensed working fluid flowing through the tubes 354 extending within the channels 348. The liquid working fluid within the channels 348 may therefore vaporize to form vaporized working fluid. The vaporized working fluid may rise (e.g., along the vertical axis 308) within the channels 348. One or more walls 344 and/or portions thereof disposed proximate the wall 350 of the vessel 306 may not contact or abut the base 336 of the canister 318 and may therefore expose at least a portion of the channels 348 to the passage 330. Accordingly , as indicated byarrows 360, liquid working fluid that vaporizes within the subcooler portion 304 may flow upward, along the vertical axis 308, into the passage 330. From the passage 330, the vaporized working fluid may flow to the vapor working fluid outlet 332 and may be directed to one or more compressors disposed along the working fluid circuit.

[0087] While the liquid working fluid within the subcooler portion 304 may vaporized due to heat transfer with the condensed working fluid directed through the tubes 354, lubricant mixed with the liquid working fluid may not vaporize within the subcooler portion 304. As a result, the vaporized working fluid may become separated from the lubricant within the subcooler portion 304. and the lubricant may remain within the subcooler portion 304 (e.g., within the channels 348). As liquid working fluid continues to vaporize and become separated from the lubricant, the lubricant remaining within the subcooler portion 304 may become increasingly more concentrated. Thus, the lubricant within the subcooler portion 304 may become purer and more suitable for use in lubricating components of the compressor system.

[0088] Accordingly, components of a lubricant return system 370 (e.g.. lubricant return system 254) may be fluidly coupled to the subcooler portion 304 (e.g., the channels 348). In the illustrated embodiment, the lubricant return system 370 includes a lubricant reservoir 372 (e.g., lubricant collector, lubricant tank) fluidly coupled to the subcooler portion 304 (e.g.. one or more of the channels 348, a laterally or radially outermost channel 348, relative to a center of the subcooler portion 304) via a lubricant inlet 374 extending through the vessel 306. Concentrated lubricant remaining within the subcooler portion 304 may flow into the lubricant reservoir 372 via the lubricant inlet 374. The lubricant return system 370 also includes one or more lubricant outlets 376. Each lubricant outlet 376 may be fluidly coupled to a respective lubricant return conduit (e.g., first lubricant return conduit 274, second lubricant return conduit 278) to enable flow of the lubricant to a corresponding compressor (e.g., lubricant sump of the compressor). In some embodiments, the lubricant return system 370 may include a pressure equalization conduit 378 extending through the vessel 306 to fluidly couple the lubricant reservoir 372 and the passage 330 (e.g., vapor working fluid passage). For example, the pressure equalization conduit 378 may have a first end 380 attached to the lubricant reservoir 372 and a second end 382, opposite the first end 380, disposed within the passage 330 proximate and/or adjacent to the vapor working fluid outlet 332 of the integrated unit 300. It should be appreciated that some embodiments of the lubricant return system 370 may not include all components of the embodiment of the lubricant return system 370 described herein. For example, some embodiments may not include the lubricant reservoir 372.

[0089] Moreover, in some embodiments, the integrated accumulator and subcooler unit 300 may include additional or alternative features configured to enable one or more of the functionalities and/or operations described herein. For example, the subcooler portion 304 may include one of the sensors 174 disposed within the cavity 342. The sensor 174 within the cavity 342 may be configured to detect a level (e.g., amount) of the liquid working fluid and/or lubricant within the cavity 342. As discussed above, the sensor 174 may be communicatively coupled to the controller 168, and the controller 168 may be configured to adjust operation of one or more components of the HVAC&R system 100 based on data and/or feedback received from the sensor 174. Additionally or alternatively, the integrated accumulator and subcooler unit 300 may include one or more sensors 174 configured to detect other operating parameters of the integrated accumulator and subcooler unit 300, such as an operating parameter (e.g., temperature, pressure, and/or flow rate) of the vapor working fluid separated from the liquid working fluid within the accumulator portion 302, an operating parameter (e.g., temperature, pressure, and/or flow rate) of the vaporized working fluid generated from the liquid working fluid within the subcooler portion 304, an operating parameter (e.g., temperature, pressure, and/or flow rate) of the condensed and/or subcooled working fluid directed through the tubes 354 and/or subcooler portion 304, an operating parameter (e.g., temperature, pressure, level, concentration, and/or flow rate) of the lubricant within the subcooler portion 304 and/or lubricant return system 370, another suitable operating parameter, or any combination thereof.

[0090] FIG. 9 is a schematic of an embodiment of a subcooler heat exchanger 400 that may be included in an embodiment of the subcooler portion 304 of the integrated accumulator and subcooler unit 300 described above with reference to FIG. 8. The subcooler heat exchanger 400 includes an embodiment of the inlet manifold 356, the tubes 354 configured to extend within the channels 348 formed via the walls 344 within the subcooler portion 304, and the outlet manifold 358. As described above, in some embodiments, the inlet manifold 356 and the outlet manifold 358 may be disposed within the cavity 342 extending along a central axis of the integrated accumulator and subcooler unit 300. A first portion 402 of each tube 354 may extend (e.g., along one or more of the channels 348) from the inlet manifold 356 toward an outer circumferential portion 404 of the vessel 306 (e.g., to a location adjacent the wall 350 of the vessel 306, to an end of the channel 348 distal to the cavity 342). A second portion 406 of each tube 354 may extend (e.g., along one or more of the channels 348) from the outer circumferential portion 404 of the vessel 306 to the outlet manifold 358 disposed within the cavity 342. Thus, the first portion 402 and the second portion 406 of each tube 354 may overlap with one another (e.g., in a layered arrangement) and/or extend along one another through the one or more channels 348. [0091] FIG. 10 is a schematic axial view of another embodiment of an integrated accumulator and subcooler unit 440 having an accumulator portion 442 (e.g., accumulator, accumulator section) and a subcooler portion 444 (e.g., subcooler, subcooling section, heat exchanger, heat exchange portion, heat exchange section) disposed within a vessel 446 (e.g., common vessel, housing, enclosure, etc.). The integrated accumulator and subcooler unit 440 may be an embodiment of the first integrated unit 128, the second integrated unit 144, and/or the integrated accumulator and subcooler unit 252 discussed above and may operate in a similar manner as previously described. Throughout the following discussion, the integrated accumulator and subcooler unit 440 and components thereof may be described with reference to a longitudinal axis or direction 448 (e.g., an axial direction), a radial axis or direction 450 (e.g., a lateral axis or direction), and a vertical axis or direction 452.

[0092] As similarly described above, the accumulator portion 442 and the subcooler portion 444 are disposed within the vessel 446. In the illustrated embodiment, the vessel 446 extends generally along the longitudinal axis 448 and is arranged in a generally horizontal orientation. The vessel 446 may be a generally cylindrical housing or enclosure extending along the longitudinal axis 448. The accumulator portion 442 and the subcooler portion 444 are at least partially offset, adjacent, and/or side by side with one another (e.g., relative to the radial axis 450) within the vessel 446. The integrated accumulator and subcooler unit 440 further include a working fluid inlet 454 (e.g., inlet conduit) configured to direct a flow of working fluid into the vessel 446. The working fluid inlet 454 may be fluidly coupled (e.g., connected, attached) to a working fluid circuit (e.g., first working fluid circuit 102, second working fluid circuit 104) and may be configured to receive a biphasic flow (e.g.. vapor and liquid mixture) of working fluid from an evaporator (e.g.. BPHE) of the HVAC&R system 100, in accordance with the present techniques. In some instances the biphasic flow of working fluid may also include an amount of lubricant, as described above. In the illustrated embodiment, the working fluid inlet 454 extends into the vessel 446 such that at least a portion of the working fluid inlet 454 (e.g., conduit) is disposed within an internal volume 456 of the vessel 446.

[0093] The accumulator portion 442 and the subcooler portion 444 each extend within the internal volume 456 of the vessel 446 from a base portion 458 of the vessel 446 (e g., relative to the vertical axis 452). The accumulator portion 442 and the subcooler portion 444 may be at least partially separated from one another by a partition or divider 460 extending from the base portion 458 and along the vertical axis 452 (e.g.. along a diameter of the vessel 446). As shown, the accumulator portion 442 extends along substantially an entire height 462 (e.g., along the vertical axis 452) of the vessel 446 (e.g., from the base portion 458 to a top portion 464 at which the working fluid inlet 454 extends into the vessel 446). The subcooler portion 444 extends from the base portion 458 and through the vessel 446 (e.g., along the vertical axis 452) along a portion of the height 462 without extending a totality of the entire height 462.

[0094] The divider 460 includes a first portion 466 that is generally aligned with the vertical axis 452 and a second portion 468 disposed at an angle (e.g.. an oblique angle) relative to the vertical axis 452. In the illustrated embodiment, the second portion 468 of the divider 460 extends from the first portion 466 at least partially along the vertical axis 452 and at least partially along the radial axis 450. The second portion 468 of the divider 460 may extend generally toward a vapor working fluid outlet 470 (e.g., conduit, pipe) of the vessel 446. In some embodiments, the second portion 468 of the divider 460 may terminate (e.g., at a distal end) at a location that is generally aligned or coaxial with a central axis 472 of the vapor working fluid outlet 470. In this way, the second portion 468 of the divider 460 may at least partially separate the accumulator portion 442 and the subcooler portion 444 along a general center or midpoint of the vapor working fluid outlet 470, thereby enabling flow of vapor working fluid to the vapor working fluid outlet 470 from the accumulator portion 442 and from the subcooler portion 444.

[0095] As similarly described above, the accumulator portion 442 (e g., the internal volume 456 of the vessel 446) may receive a biphasic working fluid from the working fluid inlet 454 (e.g., inlet conduit), which may be configured to receive the biphasic working fluid from an evaporator (e.g., BPHE) of a working fluid circuit having the integrated accumulator and subcooler unit 440. The biphasic flow of working fluid directed into the internal volume 456 and the accumulator portion 442 may undergo expansion due to a pressure drop experienced by the biphasic flow of working fluid upon entering the internal volume 456, which may cause the biphasic flow of working fluid to separate into vapor working fluid and liquid working fluid. The vapor working fluid may be draw n out of the internal volume 456, through the vapor working fluid outlet 470, via operation of a compressor disposed along the working fluid circuit and fluidly coupled to the vapor working fluid outlet 470. In some embodiments, the second portion 468 of the divider 460 may be arranged within the internal volume 456 to at least partially guide the vapor working fluid from the accumulator portion 442 tow ard the vapor working fluid outlet 470. Liquid working fluid separated from the vapor working fluid in the accumulator portion 442 may fall (e.g.. along the vertical axis 452) within the vessel 446 and may collect and/or accumulate at the base portion 458 of the vessel 446.

[0096] The subcooler portion 444 is configured to place the liquid working fluid in a heat exchange relationship with another flow of the working fluid directed along the working fluid circuit having the integrated accumulator and subcooler unit 440. Specifically, the subcooler portion 444 is configured to enable transfer of heat from a flow of condensed working fluid directed to the subcooler portion 444 from a condenser (e.g., condenser system 106) of the working fluid circuit to the liquid working fluid. The subcooler portion 444 of the illustrated embodiment includes certain features similar to those discussed above with reference to FIG. 8. For example, the subcooler portion 444 includes one or more walls 474 (e.g., partitions, dividers, extensions, panels) extending from an inner surface of the vessel 446 (e.g., a circumferential wall of the vessel 446) in a generally upward direction along the vertical axis 452. One or more of the walls 474 may extend from the base portion 458 of the vessel 446. The one or more w alls 474 form one or more channels 476 extending between the one or more walls 474. The walls 474 may have any suitable number, shape, arrangement, and/or configuration to define the one or more channels 476.

[0097] A region 478 of the accumulator portion 442 proximate and/or adjacent the base portion 458 of the vessel 446 and proximate and/or adjacent the first portion 466 of the divider 460 may be fluidly coupled to the one or more channels 476 (e g., via an opening in one or more of the w alls 474, a separation betw een one of the walls 474 and a surface (e.g., inner surface) of the vessel 446, or both to enable flow' of the liquid working fluid form the accumulator portion 442 into the channels 476. It should be appreciated that the channels 476 may define a flow path of the liquid working fluid having any suitable shape or configuration. In some embodiments, one or more of the walls 474 and/or portions thereof (e.g., proximate the accumulator portion 442) may extend (e.g., along the vertical axis 452) and be coupled to and/or fixed to the second portion 468 of the divider 460 to cover and retain the liquid working fluid and/or vaporized working within the channels 476 along at least a portion of the channels 476. One or more of the walls 474 and/or portions thereof (e.g., proximate the vapor working fluid outlet 470 of the vessel 446) may be not be attached to the second portion 468 of the divider 460 to enable flow of vaporized working fluid (e.g., from the channels 476) toward the vapor working fluid outlet 470.

[0098] As similarly described above, the subcooler portion 444 includes one or more tubes 480 (e.g., conduits, pipes, coils) extending within the subcooler portion 444 and along the one or more channels 476 defining the flow path of the liquid working fluid through the subcooler portion 444. The one or more tubes 480 may be fluidly coupled to the working fluid circuit and may be configured to receive condensed working fluid from the condenser system 106 and to direct the condensed working fluid through the subcooler portion 444 to enable transfer of heat from the condensed working fluid to the liquid working fluid within the channels 476. Additional details of the subcooler portion 444 are described further below.

[0099] The integrated accumulator and subcooler unit 440 also includes components of a lubricant return system 490 (e.g., lubricant return system 254) that are fluidly coupled to the subcooler portion 444 (e.g., the channels 476). For example, the lubricant return system 490 includes a lubricant reservoir 492 fluidly coupled to the subcooler portion 444 (e.g., one or more of the channels 476, a radially outermost channel 476, relative to a center of the vessel 446) via a lubricant inlet 494 extending through the vessel 446. The lubricant return system 490 also includes one or more lubricant outlets 496. Each lubricant outlet 496 may be fluidly coupled to a respective lubricant return conduit (e.g.. first lubricant return conduit 274, second lubricant return conduit 278) to enable flow of the lubricant to a corresponding compressor (e.g., lubricant sump of the compressor), as described above. In some embodiments, the lubricant return system 490 may include a pressure equalization conduit 498 extending through the vessel 446 to fluidly couple the lubricant reservoir 492 and a vapor discharge passage 500 (e.g., vapor working fluid passage) extending from the subcooler portion 444 to the vapor w orking fluid outlet 470.

[00100] FIG. 11 is a schematic side view of a portion of the embodiment of the integrated accumulator and subcooler unit 440 of FIG. 10. The illustrated embodiment includes similar elements and element numbers as described above with reference to FIG. 10. The illustrated embodiment also shows the tubes 480 extending along the longitudinal axis 448 and along a length 510 (e.g. an entire length) of the vessel 446. That is, the tubes 480 extend from a first longitudinal end 512 of the vessel 446 to a second longitudinal end 514. To enable flow of condensed working fluid from the working fluid circuit (e.g., from the condenser system 106) and through the tubes 480 of the subcooler portion 444, the integrated accumulator and subcooler unit 440 includes an inlet box 516 (e.g., an inlet manifold) coupled to the vessel 446 and defining an inlet cavity fluidly coupled to each tube 480 at the first longitudinal end 512. The integrated accumulator and subcooler unit 440 also includes an inlet port 518 mounted to the inlet box 516 and configured to direct the condensed working fluid into the inlet cavity of the inlet box 516 and thereby into the tubes 480. In some embodiments, the inlet box 516 may include one or more flow dividers and/or separators to divide the flow of condensed working fluid into different channels 476 extending through the vessel 446.

[00101] As the condensed working fluid is directed through the tubes 480, which are disposed within one or more of the channels 476, the liquid working fluid within the channels may absorb heat from the condensed working fluid, thereby subcooling and/or further subcooling the condensed working fluid and vaporizing the liquid working fluid within the channels 476. As indicated by arrow 520, liquid working fluid that vaporizes may rise within the vessel 446 and flow- toward the vapor working fluid outlet 470 (e.g., via operation of a compressor fluidly coupled to the vapor working fluid outlet 470). As indicated by arrows 522, vapor working fluid separated from liquid working fluid within the accumulator portion 442 may also flow toward the vapor working fluid outlet 470 (e g., without flowing through the subcooler portion 444).

[00102] Once the condensed and/or subcooled working fluid flows through the tubes 480 along the length 510 of the vessel 446, the condensed and/or subcooled working fluid may be directed from the tubes 480 into an outlet cavity defined by an outlet box 524 (e.g., an outlet manifold) coupled to the vessel 446 at the second longitudinal end 514. An outlet port 526 is mounted to the outlet box 524 and is configured to direct the condensed and/or subcooled working fluid back to the working fluid circuit to flow toward an expansion valve and evaporator of the working fluid circuit, as discussed above.

[00103] FIG. 12 is a schematic top view of a portion of the embodiment of the integrated accumulator and subcooler unit 440 of FIG. 10. The illustrated embodiment includes similarly elements and element numbers as described above and also illustrates a configuration of a flow path (e.g., liquid working fluid flow path) through the subcooler portion 444 defined by the walls 474. As shown, the walls 474 form channels 476 that define a liquid working fluid flow path that extends back and forth through the subcooler portion 444 between the first longitudinal end 512 and the second longitudinal end 514.

[00104] As shown, one or more of the channels 476 defined by the walls 474 may include multiple tubes 480 disposed therein and extending along the length 510 of the vessel 446 within the respective channel 476. In some embodiments, one or more tubes 480 may be stacked along the vertical axis 452 within one of the channels 476. Additionally, the walls 474 and the channels 476 define a meandering or zig-zag configuration of the liquid working fluid flow path through the subcooler portion 444 (e.g., back and forth between the first longitudinal end 512 and the second longitudinal end 514). As the liquid working fluid flows along the channels 476, the liquid working fluid may absorb heat from the condensed working fluid directed through the tubes 480, which may cause the liquid working fluid to vaporize and separate from lubricant within the liquid working fluid. The lubricant remaining within the subcooler portion 444 may become concentrated and may be directed to one or more compressors via the lubricant return system 490, in the manner described above.

[00105] While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

[00106] Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode, or those unrelated to enablement. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

[00107] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] ... ” or “step for [perform]ing [a function] ... ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Claims

CLAIMS:

1. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: a working fluid circuit configured to circulate a working fluid therethrough; an evaporator disposed along the working fluid circuit, wherein the evaporator is configured to place the working fluid in a heat exchange relationship with a conditioning fluid; and a vessel disposed along the working fluid circuit, wherein the vessel comprises an accumulator section and a subcooling section, wherein the working fluid circuit is configured to direct a first flow of the working fluid from the evaporator to the accumulator section of the vessel, the accumulator section is configured to separate the first flow of the working fluid into a vapor working fluid and a liquid working fluid, the vessel is configured to direct the liquid working fluid from the accumulator section to the subcooling section, and the subcooling section of the vessel is configured to place the liquid working fluid in a heat exchange relationship with a second flow of the working fluid received via the working fluid circuit.

2. The HVAC&R system of claim 1, wherein the working fluid circuit is configured to direct the second flow of the working fluid from a condenser of the working fluid circuit to the subcooling section of the vessel.

3. The HVAC&R system of claim 1, wherein the working fluid circuit is configured to direct the vapor working fluid from the accumulator section of the vessel to a compressor of the working fluid circuit.

4. The HVAC&R system of claim 1, wherein the subcooling section is configured to transfer heat from the second flow of the working fluid to the liquid working fluid within subcooling section to vaporize the liquid working fluid and to subcool the second flow of the working fluid.

5. The HVAC&R system of claim 4, comprising a lubricant return conduit extending from the subcooling section of the vessel to a compressor of the working fluid circuit, wherein the subcooling section is configured to collect lubricant separated from the liquid working fluid vaporized within the subcooling section, and the lubricant return conduit is configured to direct a flow of lubricant from the subcooling section to the compressor.

6. The HVAC&R system of claim 5, wherein the lubricant return conduit is a first lubricant return conduit, the flow of lubricant is a first flow of lubricant, the compressor is a first compressor, the HVAC&R system comprises a second lubricant return conduit extending between the subcooling section and a second compressor of the working fluid circuit, and the second lubricant return conduit is configured to direct a second flow of lubricant from the subcooling section to the second compressor.

7. The HVAC&R system of claim 6, comprising the first compressor and the second compressor, wherein the first compressor and the second compressor are configured to direct the vapor working fluid from the accumulator section to a condenser of the working fluid circuit.

8. The HVAC&R system of claim 5, wherein the lubricant return conduit does not include a valve configured to regulate the flow of lubricant from the subcooling section to the compressor.

9. The HVAC&R system of claim 1, wherein the working fluid circuit is configured to direct the second flow of the working fluid from the subcooling section, through an expansion valve, and to the evaporator.

10. The HVAC&R system of claim 1, wherein the evaporator is a brazed plate heat exchanger configured to place the working fluid in the heat exchange relationship with the conditioning fluid.

11. The HVAC&R system of claim 10, wherein the working fluid circuit is a first working fluid circuit, the working fluid is a first working fluid, the evaporator is a first evaporator, the brazed plate heat exchanger is a first brazed plate heat exchanger, and the HVAC&R system comprises: a second working fluid circuit configured to circulate a second working fluid therethrough; and a second evaporator disposed along the second working fluid circuit, wherein the second evaporator is configured to place the second working fluid in a heat exchange relationship with the conditioning fluid, and the second evaporator is a second brazed plate heat exchanger, wherein the first brazed plate heat exchanger and the second brazed plate heat exchanger are arranged in series relative to a flow of conditioning fluid directed through the first brazed plate heat exchanger and the second brazed plate heat exchanger.

12. A chiller system of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: a working fluid circuit configured to circulate a working fluid therethrough; a vessel disposed along the working fluid circuit, wherein the vessel comprises an accumulator portion configured to receive a first flow of the working fluid and separate the first flow of working fluid into vapor working fluid and liquid working fluid; and an evaporator disposed along the working fluid circuit, wherein the evaporator comprises a brazed plate heat exchanger configured to place the working fluid in a heat exchange relationship with a flow of conditioning fluid, the brazed plate heat exchanger is configured to discharge a biphasic flow of the working fluid, and the working fluid circuit is configured to direct the biphasic flow of the working fluid from the evaporator to the accumulator portion of the vessel as the first flow of the working fluid.

13. The chiller system of claim 12. comprising: an additional working fluid circuit configured to circulate the working fluid therethrough; and an additional evaporator disposed along the additional working fluid circuit, wherein the additional evaporator comprises an additional brazed plate heat exchanger configured to place the working fluid in an additional heat exchange relationship with the flow of conditioning fluid, and the brazed plate heat exchanger and the additional brazed plate heat exchanger are arranged in series relative to the flow of conditioning fluid directed through the first brazed plate heat exchanger and the second brazed plate heat exchanger.

14. The chiller system of claim 12. wherein the vessel comprises: a housing; and a subcooler portion, wherein the accumulator portion and the subcooler portion are disposed within the housing, and the subcooler portion is disposed below the accumulator portion relative to a vertical axis.

15. The chiller system of claim 14, wherein the accumulator portion is configured to direct the liquid working fluid into the subcooler portion, the housing is configured to discharge the vapor working fluid from the accumulator portion, and the working fluid circuit is configured to direct the vapor working fluid toward a compressor of the working fluid circuit.

16. The chiller system of claim 15. wherein the vessel comprises a conduit disposed within the housing and within the subcooler portion, the conduit is fluidly coupled to the working fluid circuit, and the working fluid circuit configured to direct a second flow of the working fluid from a condenser of the working fluid circuit to the conduit, and the conduit is configured to place the second flow of the working fluid in a heat exchange relationship with the liquid working fluid within the subcooler portion to transfer heat from the liquid working fluid to the second flow of the working fluid.

17. The chiller system of claim 14, comprising a lubricant return conduit extending between the subcooler portion and a compressor of the working fluid circuit, wherein the subcooler portion is configured to discharge lubricant separated from the liquid working fluid within the subcooler portion toward the lubricant return conduit, and the lubricant return conduit is configured to direct the lubricant to the compressor.

18. A chiller system of heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: an evaporator disposed along a working fluid circuit, wherein the evaporator is configured to place a first flow of working fluid in a heat exchange relationship with a flow of conditioning fluid, the evaporator is a brazed plate heat exchanger, and the brazed plate heat exchanger is configured to discharge a biphasic flow of working fluid; and an integrated accumulator and subcooler unit disposed along the working fluid circuit, wherein the integrated accumulator and subcooler unit comprises: a housing; an accumulator portion disposed within the housing, wherein the accumulator portion is configured to receive the biphasic flow of working fluid from the brazed plate heat exchanger, the accumulator portion is configured to configured to separate the biphasic flow of working fluid into vapor working fluid and liquid working fluid, and the accumulator portion is configured to discharge the vapor working fluid from the housing; and a subcooler portion disposed within the housing, wherein the subcooler portion is configured to receive the liquid working fluid from the accumulator portion and place the liquid working fluid in a heat exchange relationship with a second flow of working fluid received from a condenser of the working fluid circuit to vaporize the liquid working fluid and subcool the second flow of working fluid.

19. The chiller system of claim 18, comprising the working fluid circuit, wherein the working fluid circuit is configured to direct the second flow of working fluid from the subcooler portion, through an expansion device, and to the evaporator.

20. The chiller system of claim 18. wherein the subcooler portion is configured to collect lubricant separated from the liquid working fluid vaporized within the subcooler portion, the chiller system comprises a lubricant return system extending from the subcooler portion to a compressor of the working fluid circuit and configured to direct the lubricant from the subcooler portion to the compressor.