BACKGROUND

[0001] 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.

[0002] Vapor compression systems, such as a chiller system, 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 vapor compression system. The vapor compression system may place the working fluid in a heat exchange relationship with a conditioning fluid (e.g., water) and may deliver the conditioning fluid to equipment and/or an environment serviced by the vapor compression system. In some embodiments, the vapor compression system may include an economizer configured to improve an efficiency of the vapor compression system. For example, a first heat exchanger (e.g., a condenser) may cool the working fluid and direct the cooled working fluid to the economizer, which may reduce a pressure of the working fluid and separate the working fluid into liquid phase working fluid and vapor phase working fluid. The economizer may direct the liquid phase working fluid to a second heat exchanger (e.g., an evaporator), which may heat the working fluid. The economizer may direct the vapor phase working fluid to a compressor for pressurization. However, existing vapor compression systems, such as a vapor compression system that includes an economizer, may not provide efficient cooling and heating operations. DRAWINGS

[0003] Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

[0004] FIG. 1 is a perspective view of a building that may utilize an embodiment of a heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0005] FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0006] FIG. 3 is a schematic of an embodiment of the vapor compression system of FIG. 2, in accordance with an aspect of the present disclosure;

[0007] FIG. 4 is a schematic of an embodiment of the vapor compression system of FIG. 2, in accordance with an aspect of the present disclosure;

[0008] FIG. 5 is a schematic of an embodiment of a vapor compression system configured to provide heating and cooling operations, in accordance with an aspect of the present disclosure;

[0009] FIG. 6 is a front cross-sectional axial view of an economizer that may be utilized in a vapor compression system configured to provide heating and cooling operations, in accordance with an aspect of the present disclosure; and

[0010] FIG. 7 is a schematic of an embodiment of a vapor compression system configured to provide heating and cooling operations, in accordance with an aspect of the present disclosure. DETAILED DESCRIPTION

[0011] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are 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 implementation-specific 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.

[0012] 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.

[0013] Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system having a vapor compression system (e.g., a vapor compression circuit). The vapor compression system may include a compressor configured to pressurize a working fluid within the vapor compression system and direct the working fluid to a condenser, which may cool and condense the working fluid. The condensed working fluid may be directed toward an expansion device, which may reduce a pressure of the working fluid. From the expansion device, the cooled working fluid may be directed to an evaporator, where the working fluid may be placed in a heat exchange relationship with a conditioning fluid to cool the conditioning fluid. The compressor may then receive the working fluid from the evaporator for pressurization to restart the vapor compression cycle.

[0014] In some embodiments, the vapor compression system may include an economizer configured to receive the working fluid from the condenser. The economizer may be configured to reduce a pressure of the working fluid and separate the working fluid into liquid working fluid and vapor working fluid. The economizer may direct the liquid working fluid to the evaporator to enable the evaporator to place the liquid working fluid in a heat exchange relationship with the conditioning fluid. The vapor working fluid may be directed from the economizer to the compressor. The economizer may increase efficient operation of the vapor compression system, such as by increasing the cooling capabilities of the condenser for the conditioning fluid.

[0015] It may be desirable for the vapor compression system to provide efficient cooling and heating operations. That is, the vapor compression system may operate to cool the conditioning fluid and to heat the conditioning fluid or an additional conditioning fluid. Embodiments of the present disclosure are directed to a vapor compression system having an evaporator configured to provide cooling capabilities and a condenser configured to provide heating capabilities. For example, the vapor compression system may include a first flow path (e.g., a first circuit, a first loop) having the evaporator, and the vapor compression system may include a second flow path (e.g., a second circuit, a second loop) having the condenser. The first flow path may include a first compressor and a first expansion valve, and the second flow path may include a second compressor and a second expansion valve.

[0016] The vapor compression system also includes an economizer fluidly coupled to the first flow path and to the second flow path. The economizer may operate in different configurations to improve conditioning provided by the vapor compression system. For example, in a first configuration, the economizer may direct vapor working fluid to the second compressor. While the economizer is in the first configuration, the first compressor of the first flow path may pressurize the working fluid and direct the pressurized working fluid to the second compressor of the second flow path. The second compressor may further pressurize the working fluid and then direct the working fluid to the condenser. The condenser may enable heat ejection from the working fluid for heating purposes, such as to heat a fluid, thereby cooling the working fluid. The condenser may direct the cooled working fluid from the condenser to the second expansion valve, which may reduce a pressure of the working fluid and direct the working fluid to the economizer. The economizer may reduce the pressure of the working fluid to produce liquid working fluid and vapor working fluid. The economizer may direct the liquid working fluid to the first expansion valve, which may further reduce the pressure of the working fluid and direct the working fluid to the evaporator. The evaporator may utilize the working fluid to absorb heat for cooling purposes, such as to cool a fluid, thereby heating the working fluid. The evaporator may direct the heated working fluid to the first compressor. In the first configuration, the economizer may also receive external fluid from an external source and place the external fluid in a heat exchange relationship with the working fluid in the economizer. For instance, the external fluid may heat the working fluid to vaporize the working fluid in the economizer. As such, in the first configuration, the economizer may provide the heated vapor working fluid to the second flow path and increase heating capabilities of the second flow path.

[0017] In a second configuration, the economizer may receive additional vapor working fluid from the first compressor and may block working fluid flow from the economizer to the second compressor. The economizer may also receive the external fluid in the second configuration, the external fluid may cool the working fluid in the economizer to condense the working fluid, and the economizer may direct the condensed working fluid toward the evaporator. As such, in the second configuration, the economizer may increase cooling capabilities of the evaporator. In this manner, the economizer may transition between the first configuration and the second configuration to utilize the external fluid to improve efficient operation, such as a heating operation and/or a cooling operation, of the vapor compression system. [0018] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning, and 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) that supplies a chilled liquid, which may be used to cool the building 12. The HVAC&R system 10 may also include a boiler 16 to supply warm liquid to heat the building 12 and an air distribution system which circulates air through the building 12. The air distribution system can also 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 chilled liquid 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 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.

[0019] FIGS. 2 and 3 are embodiments of the vapor compression system 14 that can be used in the HVAC&R system 10. The vapor compression system 14 may circulate a refrigerant through a circuit starting with a compressor 32. The circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and a liquid chiller or an evaporator 38. 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 non-volatile memory 46, and/or an interface board 48.

[0020] Some examples of fluids that may be used as refrigerants in the vapor compression system 14 are hydrofluorocarbon (HFC) based refrigerants, for example, R- 410A, R-407, R-134a, R-1234ze, R1233zd, hydrofluoro olefin (HFO), "natural" refrigerants like ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based refrigerants, water vapor, or any other suitable refrigerant. In some embodiments, the vapor compression system 14 may be configured to efficiently utilize refrigerants having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere of pressure, also referred to as low pressure refrigerants, versus a medium pressure refrigerant, such as R-134a. As used herein, "normal boiling point" may refer to a boiling point temperature measured at one atmosphere of pressure.

[0021] 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 a variable speed drive (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 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.

[0022] The compressor 32 compresses a refrigerant 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 refrigerant 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 refrigerant vapor may condense to a refrigerant liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid. The liquid refrigerant from the condenser 34 may flow through the expansion device 36 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. [0023] The liquid refrigerant delivered to the evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in the condenser 34. The liquid refrigerant in the evaporator 38 may undergo a phase change from the liquid refrigerant to a refrigerant 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 cooling load 62. The cooling 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 return line 60R and exits the evaporator 38 via supply line 60S. The evaporator 38 may reduce the temperature of the cooling fluid in the tube bundle 58 via thermal heat transfer with the refrigerant. The tube bundle 58 in the evaporator 38 can include a plurality of tubes and/or a plurality of tube bundles. In any case, the vapor refrigerant exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

[0024] FIG. 4 is a schematic of the vapor compression system 14 with an intermediate circuit 64 incorporated between 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). 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 refrigerant received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66. [0025] Additionally, the intermediate vessel 70 may provide for further expansion of the liquid refrigerant because of a pressure drop experienced by the liquid refrigerant when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor 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 in the intermediate vessel may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage). The liquid that collects in the intermediate vessel 70 may be at a lower enthalpy than the liquid refrigerant exiting the condenser 34 because of the expansion in the expansion device 66 and/or the intermediate vessel 70. The liquid from intermediate vessel 70 may then flow in line 72 through a second expansion device 36 to the evaporator 38.

[0026] 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 HVAC&R system having an economizer, such as the intermediate vessel 70, and a compressor, such as the compressor 32. The discussion below describes the present techniques incorporated with embodiments of the compressor 32 configured as a single stage compressor. However, it should be noted that the systems and methods described herein may be incorporated with other embodiments of the compressor 32 and HVAC&R system 10.

[0027] With the foregoing in mind, FIG. 5 is a schematic of an embodiment of a vapor compression system 100 that includes a first flow path 102 (e.g., a chiller flow path, a cooling flow path, a cooling circuit, a cooling loop) and a second flow path 104 (e.g., a heat pump flow path, a heating flow path, a heating circuit, a heating loop) that are each configured to direct working fluid therethrough. The first flow path 102 may be configured to provide cooling capabilities for a cooling load 106, such as a fluid (e.g., water) to be cooled by the vapor compression system 100 (e.g., to provide cooling for equipment). The second flow path 104 may be configured to provide heating capabilities for a heating load 107, such as a fluid (e.g., water) to be heated by the vapor compression system 100 (e.g., to provide heat for a district heating network). For example, the first flow path 102 may include a first compressor 108, a first expansion valve 110 (e.g., a first expansion device), and an evaporator 112. The second flow path 104 may include a second compressor 114, a second expansion valve 116 (e.g., a second expansion device), and a condenser 118. The vapor compression system 100 may also include an economizer 120 configured to receive working fluid from both the first flow path 102 and the second flow path 104. The economizer 120 may transition between a first configuration and a second configuration to adjust working fluid flow through the vapor compression system 100.

[0028] For example, the economizer 120 may operate in the first configuration to enable the vapor compression system 100 to provide both a heating operation and a cooling operation. During such operation of the vapor compression system 100, the first compressor 108 may pressurize working fluid, thereby heating the working fluid, and direct the pressurized working fluid to the second compressor 114. The second compressor 114 may further pressurize the working fluid, thereby further heating the working fluid, and direct the pressurized working fluid to the condenser 118. The condenser 118 may place the pressurized working fluid in a heat exchange relationship with the heating load 107 to direct heat from the pressurized working fluid to the heating load 107, thereby heating the heating load 107 and cooling the working fluid (e g., to condense the working fluid to a liquid). The condenser 118 may then direct the working fluid (e.g., liquid working fluid) to the second expansion valve 116, which reduces a pressure of the working fluid and directs the depressurized working fluid to the economizer 120 in the first configuration.

[0029] The economizer 120 may reduce a pressure of the working fluid received from the second expansion valve 116 to separate the working fluid into vapor working fluid and liquid working fluid. In the first configuration, the economizer 120 may direct the liquid working fluid to the first expansion valve 110 and direct the vapor working fluid to the second compressor 114. The first expansion valve 110 may further reduce the pressure of the working fluid and direct the depressurized working fluid to the evaporator 112. The evaporator 112 may place the working fluid (e.g., liquid working fluid initially produced at the condenser 118) in a heat exchange relationship with the cooling load 106, thereby cooling the cooling load 106 and heating the working fluid (e.g., to vaporize the working fluid). The evaporator 112 may direct the working fluid (e.g., vapor working fluid) to the first compressor 108 for pressurization and discharge to the second compressor 114 and/or the economizer 120. Additionally, the vapor working fluid from the economizer 120 may combine with the working fluid discharged from the first compressor 108 for flow toward the second compressor 114. Working fluid flow from the compressor 108 to the economizer 120 may be blocked in the first configuration of the economizer 120.

[0030] In the second configuration of the economizer 120, the economizer 120 may receive pressurized working fluid from the first compressor 108 (e.g., flow of the vapor working fluid from the economizer 120 toward the second compressor 114 may be blocked). Thus, the economizer 120 may separate the working fluid received from the first compressor 108 into the vapor working fluid and liquid working fluid, and the economizer 120 may direct the liquid working fluid to the first expansion valve 110. However, the vapor working fluid may be blocked from discharge out of the economizer 120. In certain embodiments, the economizer 120 may not receive working fluid from the second expansion valve 116 in the second configuration. In additional or alternative embodiments, the economizer 120 may receive working fluid from the second expansion valve 116, separate the working fluid into vapor working fluid and liquid working fluid, and direct the liquid working fluid to the first expansion valve 110.

[0031] The economizer 120 may be fluidly coupled to an external source 122 (e g., an external fluid source) to condition the working fluid within the economizer 120. The external source 122 may direct an external fluid, such as water, to the economizer 120. For example, the external fluid source 122 may include a cooling tower, a natural water reservoir (e.g., a lake, a pond), a hot fluid storage tank, a process fluid reservoir, another suitable fluid source, or any combination thereof. The economizer 120 may place the external fluid received from the external source 122 in a heat exchange relationship with the working fluid to enable heat transfer between the external fluid and the working fluid to provide conditioning of the working fluid in the economizer 120. In some embodiments, the external fluid directed by the external source 122 may cool the working fluid within the economizer 120, thereby increasing a cooling capacity of the working fluid and improving operation of the vapor compression system 100 (e.g., of the evaporator 1 12) to cool the cooling load 106. In additional or alternative embodiments, the external fluid directed by the external source 122 may heat the working fluid within the economizer 120, thereby increasing a heating capacity of the working fluid and improving operation of the vapor compression system 100 (e.g., of the condenser 118) to heat the heating load 108.

[0032] In certain embodiments, the vapor compression system 100 may include or be communicatively coupled to a control system 124 (e g., control circuitry, an electronic controller, a programmable controller, an automation controller) configured to control operation of the vapor compression system 100. The control system 124 may include a memory 126 and processing circuitry 128. The memory 126 may include volatile memory, such as random-access memory (RAM), and/or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, solid-state drives, or any other non-transitory computer-readable medium storing instructions that, when executed, control operation of the vapor compression system 100. The processing circuitry 128 may be configured to execute such instructions stored in the memory 126. As an example, the processing circuitry 128 may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof. [0033] The control system 124 may be configured to operate the economizer 120 in the first configuration or in the second configuration. In other words, the control system 124 may control flow of the working fluid into the economizer 120 (e.g., from the first compressor 108) and/or out of the economizer 120 (e.g., to the second compressor 114). By way of example, the control system 124 may be communicatively coupled to a first valve 130 configured to control working fluid flow through a first conduit 132. In the first configuration, the first valve 130 may enable working fluid flow (e.g., vapor working fluid flow) from the economizer 120 to the second compressor 114 in a first flow direction 134, such as to combine with the working fluid discharged from the first compressor 108 to the second compressor 114. The control system 124 may operate the first valve 130 in the first configuration to control the flow rate of working fluid from the economizer 120 to the second compressor 114. In the second configuration, the first valve 130 may enable working fluid flow (e.g., vapor working fluid flow) from the first compressor 108 to the economizer 120 in a second flow direction 136. The control system 124 may operate the first valve 130 in the second configuration to control the flow rate of working fluid from the first compressor 108 to the economizer 120. In some embodiments, the control system 124 may be configured to operate (e.g., close) the first valve 130 to control pressurization of the working fluid via the first compressor 108. For example, control of the opening of the first valve 130 may control exposure of pressurized working fluid to the conditions within the economizer 120 (e.g., working fluid directed in the first direction 134 in the first configuration), and the pressure of the economizer 120 (e.g., of the working fluid in the economizer 120) may therefore affect the pressure of the working fluid discharged by the first compressor 108. As such, the control system 124 may operate the first valve 130 to adjust the pressure of the working fluid discharged by the first compressor 108 toward the second compressor 114.

[0034] The control system 124 may also control flow of external fluid from the external source 122 to the economizer 120. For example, the vapor compression system 100 may include a second valve 138 configured to control external fluid flow through a second conduit 140 to the economizer 120. The control system 124 may operate the second valve 138 to enable external fluid flow from the external source 122 to the economizer 120 or to block external fluid flow from the external source 122 to the economizer 120.

[0035] As an example, the control system 124 may operate the vapor compression system 100 in a first operating mode in which the economizer 120 may not condition the working fluid flow via the external fluid. For instance, the control system 124 may operate the vapor compression system 100 in the first operating mode based on a relatively low cooling demand associated with the cooling load 106 and/or a relatively low heating demand associated with the heating load 108 such that additional conditioning of the working fluid at the economizer 120 (e.g., via heat transfer between the working fluid and the external fluid) may not be desirable. Additionally or alternatively, the control system 124 may operate the vapor compression system 100 in the first operating mode in response to a determination that a difference between the temperature of the working fluid in the economizer 120 and the temperature of the external fluid is below a threshold temperature (e.g., the temperature of the working fluid in the economizer 120 is similar to the temperature of the external fluid) such that the external fluid may not be able to provide substantial conditioning of the working fluid in the economizer 120. In the first operating mode, the control system 124 may operate the second valve 138 (e.g., adjust the second valve 138 to a closed position) to block external fluid flow from the external source 122 to the economizer 120. Additionally, in the first operating mode, the control system 124 may operate the first valve 130 in the first position to enable working fluid flow (e.g., vapor working fluid flow) from the economizer 120 to the second compressor 114. Thus, the economizer 120 may be in the first configuration during the first operating mode.

[0036] The control system 124 may also operate the vapor compression system 100 in a second operating mode in which the economizer 120 may cool the working fluid. For example, the control system 124 may operate the vapor compression system 100 in the second operating mode in response to determining that there is a relatively high cooling demand associated with the cooling load 106 and/or that the temperature of the external fluid is less than the temperature of the working fluid in the economizer 120 by a threshold temperature. The cooling provided by the external fluid may reduce the temperature and/or increase the mass flow of the working fluid directed to the evaporator 112 and therefore increase the cooling capacity provided by the evaporator 112 to the cooling load 106. In the second operating mode, the control system 124 may operate the second valve 138 (e.g., adjust the second valve 138 to an open position) to enable external fluid flow from the external source 122 to the economizer 120. The control system 124 may also operate the first valve 130 in the second position to control working fluid flow from the first compressor 108 to the economizer 120. That is, the economizer 120 may be in the second configuration during the second operating mode. In this manner, working fluid that is cooled by the external fluid may be blocked from flowing to the second flow path 104 used to provide heating.

[0037] In some embodiments, in the second operating mode, working fluid flow from the first compressor 108 to the second compressor 114 may also be blocked. To this end, the control system 124 may suspend operation of the second compressor 114, adjust (e g., close) the expansion valve 116, and/or adjust a third valve 142 (e.g., to a closed position) to block working fluid flow from the first compressor 108 and/or from the economizer 120 to the second compressor 114. Indeed, operation of the second compressor 114 may be suspended in the second operating mode to block working fluid flow through the second flow path 104, thereby suspending heating operations of the vapor compression system 100. Instead, substantially all of the working fluid flow from the first compressor 108 may be cooled and condensed by the economizer 120 (e.g., via the external fluid) and directed through the first flow path 102 to provide cooling operations.

[0038] The control system 124 may further operate the vapor compression system 100 in a third operating mode in which the economizer 120 may heat the working fluid, such as in response to determining that there is a relatively high heating demand associated with the heating load 107 and/or that the temperature of the external fluid is greater than the temperature of the working fluid in the economizer 120 by a threshold temperature. The heating provided by the external fluid may increase the temperature of the working fluid directed to the condenser 118 and therefore increase the heating capacity provided by the condenser 118 to the heating load 107. To this end, in the third operating mode, the control system 124 may operate the second valve 138 (e.g., adjust the second valve 130 to the open position) to enable external fluid flow from the external source 122 to the economizer 120. The control system 124 may also operate the first valve 130 in the first position to enable working fluid flow (e.g., vapor working fluid flow heated by the external fluid) from the economizer 120 to the second compressor 114. Thus, the economizer 120 may be in the first configuration during the third operating mode.

[0039] It should be noted that in some embodiments, the control system 124 may operate the vapor compression system 100 in additional operating modes, such as operating modes between the first operating mode, the second operating mode, and the third operating mode. For example, the control system 124 may operate the first valve 130 and/or the third valve 142 to enable working fluid from the first compressor 108 to both the economizer 120 and the second compressor 114. That is, working fluid from the first compressor 108 may be apportioned between the second compressor 114 and the economizer 120. The control system 124 may additionally or alternatively operate the second valve 138 (e.g., between the open position and the closed position, such as to a partially open position) to control a particular flow rate of the external fluid from the external source 122 to the economizer 120. The control system 124 may further operate the third valve 142 (e.g., adjust an opening size of the third valve 142) to control a particular flow rate of working fluid flow from the first compressor 108 to the second compressor 114. For example, the control system 124 may operate the valves 130, 138, 142 to more acutely control the conditioning provided by the external fluid to the working fluid in the economizer 120, the cooling capacity of the evaporator 112, and/or the heating capacity of the condenser 118. [0040] Furthermore, in additional or alternative embodiments, the working fluid flow may be directed in different manners. As an example, the economizer 120 may receive a first working fluid flow from the first compressor 108 (e.g., via a first opening) and, in parallel, direct a second working fluid flow to the second compressor 114 (e.g., via a second opening). As another example, the working fluid flow directed by the second expansion valve 116 may bypass the economizer 120 and, for instance, flow directly to the first expansion valve 110.

[0041] The control system 124 may control the valves 130, 138, 142 based on data received from sensors 144. For example, the data may indicate various operating parameters, such as an ambient temperature, a temperature of the working fluid (e.g., in the economizer 120, in the evaporator 112, in the condenser 118), a temperature of the external fluid, a cooling demand associated with the cooling load 106, a heating demand associated with the heating demand 107, an operating capacity of the first compressor 108 and/or of the second compressor 114, a position of the valves 130, 138, 142, a flow rate of the working fluid (e.g., through any of the valves 130, 138, 142), another suitable parameter, or any combination thereof. Thus, the control system 124 may operate the vapor compression system 100 in the first operating mode, the second operating mode, the third operating, or any other operating mode based on the data received from the sensors 144.

[0042] FIG. 6 is an axial cross-sectional view of an embodiment of the economizer 120. The economizer 120 may include a shell 168 (e.g., an enclosure, a housing) that defines an internal volume 170 in which the working fluid and/or the external fluid may be directed. For example, the economizer 120 may include a vapor section 172 and a conditioning section 174 (e.g., a cooling section, a heating section) within the internal volume 170. The conditioning section 174 may include a first set of tubes 176 (e.g., a first tube bundle, a first pass) through which the external fluid may flow. In some embodiments, the economizer 120 may also include a second set of tubes 177 (e.g., a second tube bundle, a second pass, a subcooler, a superheater) through which the external fluid may flow. Thus, the external fluid flow may circulate between the economizer 120 and the external source 122 via the first set of tubes 176 and/or the second set of tubes 177. Although the illustrated economizer 120 includes two sets of tubes 176, 177, the economizer 120 may include any suitable quantity of sets of tubes, such as three or more sets of tubes, for conditioning the working fluid via the external fluid.

[0043] The economizer 120 may include an inlet 178 configured to enable the economizer 120 to receive the working fluid flow (e.g., a mixture of liquid working fluid and vapor working fluid) from the second expansion valve 116. The economizer 120 may also include an outlet 180 configured to enable the economizer 120 to discharge the working fluid flow to the first expansion valve 110. As an example, the pressure of the working fluid flow directed from the second expansion valve 116 may be partially reduced, and the economizer 120 may further reduce the pressure of the working fluid flow received from the second expansion valve 116 to separate the working fluid flow into liquid working fluid and vapor working fluid within the internal volume 170. The vapor working fluid may be directed to the vapor section 172, and the liquid working fluid may be directed through the conditioning section 174 (e g., by a gravitational force) toward the outlet 180.

[0044] Moreover, the economizer 120 may include an opening 182 through which working fluid may flow. For instance, the working fluid (e.g., vapor working fluid) may flow out of the internal volume 170 in the first direction 134 through the opening 182, such as toward the second compressor 114, in the first configuration of the economizer 120. Additionally, the working fluid may flow into the internal volume 170 in the second direction 136 through the opening 182, such as from the first compressor 108, in the second configuration of the economizer 120. In this way, working fluid may flow in either direction through the opening 182 based on the configuration of the economizer 120. [0045] The first set of tubes 176 and/or the second set of tubes 177 may place the external fluid in a heat exchange relationship with the working fluid directed across the first set of tubes 176, such as the liquid working fluid flowing toward the outlet 180. As an example, in the second operating mode, the first set of tubes 176 may enable the external fluid to cool the working fluid, thereby condensing the working fluid. The second set of tubes 177 may enable the external fluid to further cool (e.g., subcool) the working fluid, and the working fluid cooled by the first set of tubes 176 and/or the second set of tubes 177 may be discharged from the economizer 120 via the outlet 180. Thus, the conditioning section 174 may cause condensation of the working fluid to provide greater amounts of liquid working fluid in the second operating mode. Additionally, the working fluid may flow in the first direction 136 through the opening 182 into the economizer 120 in the second operating mode. In the third operating mode, the first set of tubes 176 may enable the external fluid to heat the working fluid, thereby vaporizing the working fluid. The second set of tubes 177 may provide further heating of the working fluid via the external fluid to facilitate vaporization of the working fluid. Heating of the working fluid may therefore produce vapor working fluid that flows toward the vapor section 172, and the vapor working fluid may be discharged from the economizer 120 via the opening 182 in the first direction 134. As such, the conditioning section 174 may provide greater amounts of vapor working fluid in the third operating mode. Any liquid working fluid that remains after heating of the working fluid via the external fluid may be discharged from the economizer 120 via the outlet 180.

[0046] In the first operating mode in which external fluid flow through the economizer 120 is blocked, the working fluid may not exchange heat with the external fluid. Instead, in the first operating mode, depressurization of the working fluid via the economizer 120 may produce the vapor working fluid, which is discharged from the economizer 120 via the opening 182, and the liquid working fluid, which is discharged from the economizer 120 via the outlet 180. However, the first set of tubes 176 and/or the second set of tubes 177 may not cause substantial changes in temperature or state of the working fluid in the first operating mode. [0047] FIG. 7 is a schematic diagram of an embodiment of the vapor compression system 100 having multiple economizers. For example, the vapor compression system 100 may include the first flow path 102, the second flow path 104, and an intermediate flow path 210. A first economizer 212 (e.g., the economizer 120) may be configured to receive working fluid from the first flow path 102 and from the intermediate flow path 210. A second economizer 214 may be configured to receive working fluid from the intermediate flow path 210 and from the second flow path 104. The intermediate flow path 210 may include an intermediate compressor 216 and an intermediate expansion valve 218 (e.g., an intermediate expansion device).

[0048] For instance, the first compressor 108 may pressurize working fluid and direct the working fluid to the intermediate compressor 216, the intermediate compressor 216 may further pressurize the working fluid and direct the working fluid to the second compressor 114, and the second compressor 114 may further pressurize the working fluid and direct the working fluid to the condenser 118, which may utilize the working fluid to heat the heating load 107. The condenser 118 may direct the working fluid to the second expansion valve 116, which may reduce a pressure of the working fluid and direct the working fluid to the second economizer 214. The second economizer 214 may further reduce the pressure of the working fluid to produce vapor working fluid and liquid working fluid. The second economizer 214 may direct the vapor working fluid to the second compressor 114 for pressurization, and the second economizer 214 may direct the liquid working fluid to the intermediate expansion valve 218. The intermediate expansion valve 218 may reduce the pressure of the working fluid and direct the working fluid to the first economizer 212. The first economizer 212 may reduce the pressure of the working fluid and also produce vapor working fluid and liquid working fluid. The first economizer 212 may direct the liquid working fluid to the first expansion valve 110.

[0049] The first economizer 212 may transition between the first configuration and the second configuration (e.g., via operation of the control system 124). In the first configuration, the first economizer 212 may discharge vapor working fluid to the intermediate compressor 216, such as through the first conduit 132. In the second configuration, the first economizer 212 may receive working fluid from the first compressor 108, and working fluid flow from the first economizer 212 to the intermediate compressor 216 may be blocked. In some embodiments, the first economizer 212 may not receive working fluid from the intermediate expansion valve 218 in the second configuration, and operation of the intermediate flow path 210 may be suspended.

[0050] By way of example, the first economizer 212 may receive the external fluid from the external source 122 via the second conduit 140 and may operate in the first configuration or in the second configuration based on conditioning provided by the external fluid. For instance, in the first operating mode in which the external fluid does not provide any conditioning for the working fluid in the first economizer 212, the first economizer 212 may operate in the first configuration to direct vapor working fluid to the intermediate compressor 216. In the second operating mode in which the external fluid may cool the working fluid in the first economizer 212, the first economizer 212 may operate in the second configuration to receive working fluid from the first compressor 108. In the third operating mode in which the external fluid may heat the working fluid in the first economizer 212, the first economizer 212 may operate in the first configuration to direct vapor working fluid to the intermediate compressor 216.

[0051] In some embodiments, an intermediate load 220 may be fluidly connected to the second economizer 214. For example, the intermediate load 220 may direct an intermediate fluid to the second economizer 214. The second economizer 214 may place the working fluid in a heat exchange relationship with the intermediate fluid. For instance, the second economizer 214 may enable the working fluid to heat the intermediate fluid (e.g., to provide heat for a drying process). In additional or alternative embodiments, the second economizer 214 may enable the working fluid to cool the intermediate fluid. The control system 124 may operate a fourth valve 222 to control fluid flow between the second economizer 214 and the intermediate load 220 via a fourth conduit 224 to provide a desirable amount of conditioning for the intermediate fluid (e.g., to adjust the temperature of the intermediate fluid toward a target temperature).

[0052] In certain embodiments, the second economizer 214 may also transition between a first configuration and a second configuration (e.g., via operation of the control system 124). For example, in the first configuration, the second economizer 214 may discharge vapor working fluid to the second compressor 114, and in the second configuration, the second economizer 214 may receive working fluid from the intermediate compressor 216 and block working fluid flow from the second economizer 214 to the second compressor 114. The second economizer 214 may not receive working fluid from the second expansion valve 116 in the second configuration, and operation of the second flow path 104 may be suspended.

[0053] While only certain features and embodiments of the present disclosure 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 resequenced according to alternative embodiments. It is, therefore, to be noted that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the present disclosure. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the present disclosure, or those unrelated to enabling the claimed embodiments). 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.

[0054] 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).