HVAC system with bypass conduit

Abstract

To provide an HVAC system that can increase the flow rate of a refrigerant from an economizer to an evaporator.SOLUTION: A heating, ventilation, and / or air conditioning (HVAC) system includes a vessel 70 configured to receive a refrigerant from a condenser 34 of the HVAC system, an evaporator 38 configured to receive the refrigerant from the vessel 70, a first conduit 100 configured to direct a first flow of the refrigerant to a first inlet 107 of the evaporator 38, and a second conduit 108 configured to direct a second flow of the refrigerant to a second inlet 109 of the evaporator 38. The second inlet 109 is above the first inlet 107 relative to a vertical axis.SELECTED DRAWING: Figure 5

Description

Related Applications

[0001] Cross - References to Related Applications This application claims priority and the benefit of U.S. Provisional Patent Application No. 63 / 085,842, filed on September 30, 2020, entitled "HVAC SYSTEM WITH BYPASS CONDUIT", the entire disclosure of which is incorporated herein by reference for all purposes.

Technical Field

[0002] This section is intended to introduce the reader to various aspects of the art that may be related to the various aspects of the present disclosure described below. This discussion is thought to be useful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be noted that these descriptions should be read from this perspective and not as an approval of the prior art.

Background Art

[0003] Refrigeration systems are used for a variety of settings and many purposes. For example, a refrigeration system can operate as a free cooling system and / or a mechanical cooling system for cooling, heating, dehumidifying, or otherwise conditioning a fluid. In some cases, the free cooling system can include a liquid-to-air heat exchanger used in some heating, ventilation, and air conditioning applications. Additionally, the mechanical cooling system can include a vapor compression refrigeration cycle, which can circulate a refrigerant through a condenser, an evaporator, a compressor, an economizer, and / or an expansion device. In the condenser, the refrigerant is desuperheated, condensed, and / or subcooled, and a liquid or predominantly liquid refrigerant can be directed to the economizer, where the pressure of the refrigerant can be reduced and a portion of the refrigerant can be evaporated. The liquid refrigerant can be directed from the economizer to the evaporator, where the liquid refrigerant evaporates by absorbing thermal energy or heat from an airstream and / or a conditioning fluid such as water, thereby cooling the conditioning fluid. In some applications, the vapor refrigerant can be directed from the economizer to the compressor to be recompressed. Under some operating conditions, the flow of refrigerant from the economizer to the evaporator can be limited or otherwise restricted. SUMMARY OF THE INVENTION

[0004] The following presents a summary of the specific embodiments disclosed herein. These aspects are presented only to provide a concise summary to the reader of these specific embodiments and it should be noted that these aspects are not intended to limit the scope of the present disclosure. Indeed, the present disclosure can encompass various aspects that may not be described below.

[0005] In one embodiment, a heating, ventilation, and / or air conditioning (HVAC) system includes a container configured to receive refrigerant from a condenser of the HVAC system, an evaporator configured to receive refrigerant from the container, a first conduit configured to direct a first flow of refrigerant to a first inlet of the evaporator, and a second conduit configured to direct a second flow of refrigerant to a second inlet of the evaporator. The second inlet is above the first inlet with respect to a vertical axis.

[0006] In one embodiment, a heating, ventilation, and / or air conditioning (HVAC) system includes a container configured to receive refrigerant from a condenser and separate the refrigerant received from the condenser into vapor refrigerant and liquid refrigerant, a first conduit configured to direct a first flow of the liquid refrigerant to a first inlet of an evaporator of the HVAC system, and a second conduit configured to direct a second flow of the liquid refrigerant to a second inlet of the evaporator. The first conduit includes a bypass valve, and the second inlet is above the first inlet with respect to a vertical axis. The HVAC system also includes a controller communicatively coupled to the bypass valve and configured to operate the bypass valve to control the flow rate of the first flow of the liquid refrigerant to the evaporator via the first conduit.

[0007] In one embodiment, a heating, ventilation, and / or air conditioning (HVAC) system includes a condenser, an intermediate container configured to receive refrigerant from the condenser, an evaporator configured to receive refrigerant from the intermediate container, a first conduit extending between the condenser and the intermediate container, a second conduit extending between the intermediate container and a first inlet of the evaporator, and a third conduit extending between the intermediate container and a second inlet of the evaporator. The first conduit includes an expansion valve configured to reduce the pressure of the refrigerant directed through the first conduit to enable separation of the refrigerant into liquid refrigerant and vapor refrigerant within the intermediate container. The second conduit is configured to direct liquid refrigerant into the evaporator via the first inlet, the second inlet is above the first inlet with respect to a vertical axis, and the third conduit is configured to direct liquid refrigerant into the evaporator via the second inlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0008]

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DETAILED DESCRIPTION OF THE INVENTION

[0009] One or more specific embodiments are described below. To provide a concise description of these embodiments, not all features of actual implementations are described herein. In the development of any such actual implementation, as in any engineering or design project, many implementation-specific decisions may need to be made that can vary from implementation to implementation, such as compliance with system-related and industry-related constraints to achieve the developer's specific goals. It should be noted that such development efforts can be complex and time-consuming, but nevertheless, for those skilled in the art who benefit from the present disclosure, they are routine tasks in design, fabrication, and manufacturing.

[0010] When introducing elements of various embodiments of the present disclosure, the articles "a", "an", and "the" are intended to mean that one or more of the elements are present. The terms "comprising", "including", and "having" are intended to be inclusive and mean that additional elements other than the recited elements may exist. Further, note that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0011] The present disclosure is directed to an HVAC system configured to direct a refrigerant through a refrigerant circuit. The refrigerant undergoes a phase change in order for the HVAC system to be able to condition an interior space of a structure and / or a cooling fluid (e.g., water), and flows through a plurality of conduits and components disposed along the refrigerant circuit. For example, the refrigerant can be cooled through a condenser of the refrigerant circuit in order to transition from a gas phase to a liquid phase. The refrigerant can be directed from the condenser toward an evaporator (e.g., a falling film evaporator) of the refrigerant circuit, where the refrigerant transitions from a liquid phase to a gas phase within the evaporator and can cool a cooling fluid (e.g., water) in a heat exchange relationship with the refrigerant. In some embodiments, the refrigerant circuit can include an economizer that can receive liquid refrigerant from the condenser and separate vapor refrigerant from the liquid refrigerant. The economizer can then direct the liquid refrigerant to the evaporator and prevent the vapor refrigerant from flowing to the evaporator in order to achieve a desired operation (e.g., efficiency) of the evaporator and cool the cooling fluid. Alternatively, the economizer can direct the vapor refrigerant to a compressor of the refrigerant circuit for compression. The refrigerant can flow through a plurality of conduits and components disposed along the refrigerant circuit. For example, the refrigerant can be cooled through a condenser of the refrigerant circuit in order to transition from a gas phase to a liquid phase. The refrigerant can be directed from the condenser toward an evaporator (e.g., a falling film evaporator) of the refrigerant circuit, where the refrigerant transitions from a liquid phase to a gas phase within the evaporator and can cool a cooling fluid (e.g., water) in a heat exchange relationship with the refrigerant. In some embodiments, the refrigerant circuit can include an economizer that can receive liquid refrigerant from the condenser and separate vapor refrigerant from the liquid refrigerant. The economizer can then direct the liquid refrigerant to the evaporator and prevent the vapor refrigerant from flowing to the evaporator in order to achieve a desired operation (e.g., efficiency) of the evaporator and cool the cooling fluid. Alternatively, the economizer can direct the vapor refrigerant to a compressor of the refrigerant circuit for compression.

[0012] In some situations, the refrigerant may not easily flow into the evaporator. For example, in an existing HVAC system, a relatively high pressure in the condenser and / or economizer can drive the refrigerant to flow into the evaporator. However, if the pressure difference between the economizer and the evaporator, and / or the pressure difference between the condenser and the evaporator is low, the refrigerant may not flow into the evaporator at a sufficient rate. More specifically, the low-pressure vapor refrigerant can be collected or accumulated in a conduit extending between the economizer and the evaporator and / or in an expansion valve (e.g., disposed along a conduit extending between the economizer and the evaporator) disposed between the economizer and the evaporator. For example, the pressure of the refrigerant in the condenser can become low, and the economizer can further lower the pressure of the refrigerant, which can reduce the flow rate of the refrigerant into the evaporator, thereby reducing the operating efficiency of the HVAC system. In fact, a low flow rate of the refrigerant to the evaporator can cause unstable operation of certain components (e.g., the compressor) of the HVAC system.

[0013] Accordingly, it is now recognized that increasing the flow rate of refrigerant from the economizer to the evaporator can increase or maintain the operating efficiency of the HVAC system. Thus, embodiments of the present disclosure are directed to an HVAC system having a refrigerant circuit comprising an economizer and a bypass line or conduit configured to allow an increase in the flow of refrigerant into the evaporator. For example, the bypass line may extend between the condenser and the evaporator, or may extend between the economizer and the evaporator. The bypass line can facilitate the flow of liquid refrigerant to the evaporator and increase the flow rate of refrigerant to the evaporator with a low pressure differential of the refrigerant within the refrigerant circuit. For example, the bypass line is arranged to allow gravity and / or the pressure of the refrigerant (e.g., the head pressure or pressure difference between the condenser and the evaporator) to drive the liquid refrigerant to flow through the bypass line to the evaporator, rather than through a primary line configured to direct the refrigerant to the evaporator (e.g., from the economizer). The bypass line may include a valve configured to regulate the amount of refrigerant flowing through the bypass line. For example, the valve may be partially or fully opened based on sensor data indicative of the operating parameters of the HVAC system to allow the flow of refrigerant to the evaporator at a desired rate (e.g., relative to the flow rate of the liquid refrigerant directed through the primary line) through the bypass line. As described above, in some embodiments, the bypass line fluidly couples (e.g., extends between) the economizer to the evaporator. In additional or alternative embodiments, the bypass line allows liquid to flow directly from the condenser to the evaporator without flowing through the economizer. The bypass line can increase the flow rate of refrigerant into the evaporator to increase or maintain the operating efficiency of the HVAC system, such as during examples of low and / or varying head pressures (e.g., a relatively low refrigerant pressure within the condenser and / or a relatively high refrigerant pressure within the evaporator).

[0014] Turning now to the drawings, FIG. 1 is a perspective view of one embodiment of an environment of a heating, ventilation, and air conditioning (HVAC) system 10 within a building 12 for a typical commercial setting. The HVAC system 10 can include a vapor compression system 14 that supplies a cooled liquid that can be used to cool the building 12. The HVAC system 10 can also include a boiler 16 for supplying a warm liquid to heat the building 12 and an air distribution system for circulating 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 can include a heat exchanger connected to the boiler 16 and the vapor compression system 14 by conduits 24. The heat exchanger within the air handler 22 can receive either the heated liquid from the boiler 16 or the cooled liquid from the vapor compression system 14, depending on the operating mode of the HVAC system 10. The HVAC system 10 is shown with a separate air handler for each floor of the building 12, but in other embodiments, the HVAC system 10 can include an air handler 22 and / or other components that can be shared between floors.

[0015] FIGS. 2 and 3 illustrate embodiments of a vapor compression system 14 that can be used within the HVAC system 10. The vapor compression system 14 can circulate refrigerant through a circuit that begins with a compressor 32. The circuit can also include a condenser 34, an expansion valve or expansion device 36, and a liquid chiller or evaporator 38. The vapor compression system 14 can include a control panel 40 (e.g., a controller) having an analog-to-digital (A / D) converter 42, a microprocessor 44, a non-volatile memory 46, and / or further an interface board 48.

[0016] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSD) 52, a motor 50, a compressor 32, a condenser 34, an expansion valve or device 36, and / or an 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 AC power having a specific fixed line voltage and fixed line frequency from an alternating current (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 power source or a direct current (DC) power source. The motor 50 may include any type of electric motor that can be powered directly from a VSD or 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.

[0017] The compressor 32 compresses the 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 to the condenser 34 by the compressor 32 may transfer heat to a cooling fluid (e.g., water or air) within the condenser 34. The refrigerant vapor may condense into a refrigerant liquid within the condenser 34 as a result of the heat transfer with the cooling fluid. The refrigerant liquid 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 that supplies the cooling fluid to the condenser.

[0018] The refrigerant liquid delivered to the evaporator 38 may be the same cooling fluid used in the condenser 34 or may be another cooling fluid and can absorb heat from it. The refrigerant liquid in the evaporator 38 can undergo a phase change from the refrigerant liquid to 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 the 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 the return line 60R and exits the evaporator 38 via the supply line 60S. The evaporator 38 can reduce the temperature of the cooling fluid within the tube bundle 58 via heat transfer with the refrigerant. The tube bundle 58 within the evaporator 38 can include a plurality of tubes and / or a plurality of tube bundles. In any case, the refrigerant vapor exits the evaporator 38 and returns to the compressor 32 via the suction line to complete the cycle.

[0019] FIG. 4 is a schematic of a vapor compression system 14 having an intermediate circuit 64 incorporated between the condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line or conduit 68 that is directly fluid connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluid coupled to the condenser 34. As shown in the illustrated embodiment of FIG. 4, the inlet line 68 It includes a first expansion device 66 positioned upstream of the intermediate container 70. In some embodiments, the intermediate container 70 can be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate container 70 can be configured as a heat exchanger or a “surface economizer”. In the illustrated embodiment of FIG. 4, the intermediate container 70 is used as a flash tank, and the first expansion device 66 is configured to lower (e.g., expand) the pressure of the refrigerant liquid received from the condenser 34. During the expansion process, a portion of the liquid can vaporize, enabling the separation of the refrigerant into liquid and vapor within the intermediate container 70. Further, the intermediate container 70 can provide further expansion of the refrigerant liquid due to the pressure drop that the refrigerant liquid experiences when entering the intermediate container 70 (e.g., due to the sudden increase in volume experienced when entering the intermediate container 70). The vapor within the intermediate container 70 can be drawn out by the compressor 32 through the suction line 74 of the compressor 32. In other embodiments, the vapor within the intermediate container 70 can be drawn into an intermediate stage of the compressor 32 (e.g., rather than the suction stage). In further embodiments, the vapor compression system 14 can include an additional compressor 71 fluidly coupled to the intermediate container 70 to facilitate drawing vapor out of the intermediate container 70. That is, the additional compressor 71 (e.g., a compressor having a capacity smaller than that of the compressor 32) can draw vapor out of the intermediate container 70 and compress the vapor, and the second compressor 71 can discharge the compressed refrigerant to the condenser 34. The operation of the additional compressor 71 can facilitate the operation of the compressor 32 by improving the efficiency of the operation of the compressor 32 and / or by maintaining the structural integrity of the compressor 32, etc. In any case, the liquid accumulating in the intermediate container 70 can have an enthalpy lower than that of the refrigerant liquid exiting the condenser 34 due to the expansion device 66 and / or the expansion within the intermediate container 70. Then, the liquid from the intermediate container 70 can flow through the line 72 and through the second expansion device 36 to the evaporator 38.

[0020] In some embodiments, it may be advantageous to include a bypass line (e.g., a bypass conduit) within a vapor compression system, such as vapor compression system 14, to improve the efficiency of the vapor compression system. For example, when the pressure differential within vapor compression system 14 (e.g., between intermediate vessel 70 and evaporator 38 and / or between condenser 34 and evaporator 38) is relatively low, the refrigerant (e.g., liquid refrigerant) may stack, or accumulate, within intermediate vessel 70 and / or within the primary conduit extending from intermediate vessel 70 to evaporator 38, rather than flowing readily into evaporator 38 (e.g., via the primary conduit). In some embodiments, evaporator 38 of vapor compression system 14 may be a falling-film evaporator, which may be positioned at a greater height (e.g., relative to condenser 34, relative to gravity) than other conventional systems and may restrict the flow of refrigerant from intermediate vessel 70 to evaporator 38. Due to the restricted flow of refrigerant into evaporator 38, the cooling capacity provided by evaporator 38 may be limited or restricted, and / or the operation of other components of vapor compression circuit 14 may be adversely affected.

[0021] Accordingly, the bypass line can direct at least a portion of the refrigerant along an alternative flow path (e.g., different from the flow path provided by the primary conduit) that provides a lower resistance to the flow of the refrigerant than that of the primary conduit. In some embodiments, the bypass line can direct the refrigerant from the condenser 34 and / or the intermediate vessel 70 toward the bottom of the evaporator 38, enabling the refrigerant to be directed through the bypass line to the evaporator 38 using gravity. Additionally, the pressure within the condenser 34 and / or from the intermediate vessel 70 (e.g., the head pressure of the refrigerant) can also contribute to directing the refrigerant through the bypass line to the evaporator 38. In certain embodiments, the bypass line can include a valve, and a control system of the vapor compression system 14, such as the control panel 40, can selectively operate the valve to control the flow of refrigerant to the evaporator 38 via the bypass line. By way of example, the control panel 40 can open or close the position of the valve, or otherwise adjust it, to improve the operating capacity, performance, and / or efficiency of the vapor compression system 14 (e.g., based on feedback or data received from other components of the vapor compression system 14).

[0022] FIG. 5 is a schematic diagram of an embodiment of a vapor compression system 14 having a compressor 32, a condenser 34, an evaporator 38, and an intermediate vessel 70. During operation of the vapor compression system 14, the compressor 32 is configured to receive refrigerant (e.g., vapor refrigerant) from the evaporator 38 via a suction line or conduit 92, pressurize the refrigerant, and direct the pressurized refrigerant to the condenser 34 via a discharge line or conduit 94. The condenser 34 can cool the refrigerant and accumulate the refrigerant as liquid refrigerant 96 within the condenser 34, and the liquid refrigerant 96 can be directed to the intermediate vessel 70 where the pressure of the liquid refrigerant 96 is reduced to transition or "flash" the liquid refrigerant 96 into vapor refrigerant and liquid refrigerant 98. The intermediate vessel 70 can direct the liquid refrigerant 98 to the evaporator 38 and can cool a cooling fluid in a heat exchange relationship with the liquid refrigerant 98. The pressure reduction of the liquid refrigerant 96 from the condenser 34 causes the liquid refrigerant 98 within the intermediate vessel 70 to have a temperature lower than the temperature of the liquid refrigerant 96. In this way, the intermediate vessel 70 enables an increase in the cooling capacity of the evaporator 38. Further, the intermediate vessel 70 can prevent vapor refrigerant from being directed to the evaporator 38 and maintain the efficiency of the cooling provided by the evaporator 38. In some embodiments, the vapor refrigerant can be returned from the intermediate vessel 70 to the compressor 32 (e.g., via the suction line 74 described with respect to FIG. 4) for recompression.

[0023] The vapor compression system 14 further includes a bypass line or conduit 100 (e.g., a first line or conduit) that extends between the intermediate vessel 70 and the evaporator 38 and fluidly couples the intermediate vessel 70 and the evaporator 38. In the illustrated embodiment, the vapor compression system 14 includes a first outlet line or conduit 102 fluidly connected to the outlet 103 of the intermediate vessel 70 to enable a liquid refrigerant 98 (e.g., a portion of the refrigerant within the intermediate vessel 70 in the liquid phase) to flow out of the intermediate vessel 70. The bypass line 100 extends between and fluidly couples the first outlet line 102 and the bottom section or portion 106 of the evaporator 38 (e.g., the first inlet 107 of the evaporator 38 at the bottom section 106). In this way, the liquid refrigerant 98 can flow from the intermediate vessel 70 through the first outlet line 102 and the bypass line 100 to the bottom section 106 of the evaporator 38. The illustrated vapor compression system 14 also includes a primary line or conduit 108 (e.g., a second line or conduit) that extends between and fluidly couples the first outlet line 102 and the upper section or portion 110 of the evaporator 38 (e.g., the second inlet 109 of the evaporator 38 at the upper section 110). Thus, the liquid refrigerant 98 can flow from the intermediate vessel 70 through the first outlet line 102 and the primary line 108 to the upper section 110 of the evaporator 38. In the illustrated embodiment, each of the bypass line 100 and the primary line 108 is fluidly coupled to the same first outlet line 102, but in additional or alternative embodiments, the bypass line 100 and the primary line 108 can be separately coupled to the intermediate vessel 70 (e.g., to separate the outlets of the intermediate vessel 70).

[0024] The bypass line 100 provides an additional flow path (e.g., a flow path that is at least partially separate and distinct from the flow path defined by the primary line 108) for the liquid refrigerant 98 to flow from the intermediate vessel 70 to the evaporator 38. The additional flow path provided by the bypass line 100 may impose less resistance to the flow of the liquid refrigerant 98 compared to the flow path of the primary line 108. For example, the primary line 108 may direct the liquid refrigerant 98 further upward with respect to the vertical axis 112 (e.g., against gravity) compared to the liquid refrigerant 98 directed through the bypass line 100. That is, the second inlet 109 in the upper section 110 of the evaporator 38 may be above the first inlet 107 in the bottom section 106 of the evaporator 38 with respect to and along the vertical axis 112. Thus, the liquid refrigerant 98 can be driven to flow through the bypass line 100 using less fluid pressure or force compared to flowing through the primary line 108. In fact, the height difference 114 between the upper portion 116 of the primary line 108 and the bottom portion 118 of the bypass line 100, together with the pressure caused by the level of the liquid refrigerant 98 in the intermediate vessel 70, can more readily facilitate the flow of the liquid refrigerant 98 through the bypass line 100 to the evaporator 38. The bypass line 100 is sized such that the liquid refrigerant 98 can flow into the evaporator 38 at a desired flow rate obtain. For example, the bypass line 100 may have an opening size (e.g., diameter) that is approximately equal to or substantially smaller than the opening size (e.g., diameter) of the primary line 108. Alternatively, the bypass line 100 may have an opening size (e.g., diameter) that is substantially larger than that of the primary line 108.

[0025] In the illustrated embodiment, the outlet 103 of the intermediate container 70 is below the first inlet 107 and the second inlet 109 of the evaporator 38 with respect to the vertical axis 112. However, in additional or alternative embodiments, the outlet 103 may be above the first inlet 107 and / or the second inlet 109 with respect to the vertical axis 112. For example, at least a portion of the intermediate container 70 may be positioned above the evaporator 38 (e.g., above the second inlet 109). In such an embodiment, the first inlet 107 can remain below the second inlet 109 such that the bypass line 100 imposes less resistance on the flow of the liquid refrigerant 98 compared to that of the primary line 108.

[0026] The evaporator 38 illustrated in FIG. 5 can be a falling-film evaporator, a flooded evaporator, or a hybrid falling-film and flooded evaporator configured to operate as both. For example, the evaporator 38 can operate as a falling-film evaporator when the liquid refrigerant 98 flows through the primary line 108 and into the upper section 110 of the evaporator 38 via the second inlet 109 of the evaporator 38 (e.g., without using the bypass line 100 to direct the liquid refrigerant 98 to the evaporator 38). In some embodiments, the flow of the liquid refrigerant 98 through the bypass conduit 100 can be blocked during operation of the evaporator 38 as a falling-film evaporator. The liquid refrigerant 98 can flow through the evaporator 38 from the upper section 110 towards the bottom section 106, for example, due to gravity. The evaporator 38 can enable the liquid refrigerant 98 to cool the cooling fluid while flowing from the upper section 110 towards the bottom section 106 in a heat exchange relationship with the cooling fluid (e.g., via tubes disposed within the evaporator 38 configured to direct the cooling fluid therethrough). After the cooling fluid is cooled within the evaporator 38, the cooling fluid can then be directed to conditioning equipment (e.g., a terminal unit, an air handler) to condition another fluid (e.g., air) with the cooling fluid.

[0027] In addition, the evaporator 38 can operate as a flooded evaporator when the liquid refrigerant 98 flows through the bypass line 100 and into the bottom section 106 of the evaporator 38 via the first inlet 107 (e.g., when the pressure difference between the intermediate container 70 and the evaporator 38 is relatively small). That is, the liquid refrigerant 98 can accumulate in the bottom section 106. The evaporator 38 can enable the liquid refrigerant 98 to cool the cooling fluid while accumulating in the bottom section 106 in a heat exchange relationship with the cooling fluid. Further, the evaporator 38 can operate simultaneously as both a falling-film evaporator and a flooded evaporator (e.g., a hybrid falling-film evaporator, or a hybrid flooded evaporator, and / or a hybrid falling-film and flooded evaporator) when the liquid refrigerant 98 is induced into the upper section 110 and the bottom section 106 of the evaporator 38 through both the primary line 108 and the bypass line 100, respectively. For example, the liquid refrigerant 98 can flow from the upper section 110 to the bottom section 106, and accumulate in the bottom section 106 within the evaporator 38 to exchange heat with the cooling fluid induced through the evaporator 38.

[0028] For this purpose, and as briefly described above, the evaporator 38 can include a first tube bundle 58A positioned below the second inlet 109 through which the cooling fluid is induced. The liquid refrigerant 98 induced into the upper section 110 of the evaporator 38 via the primary line 108 can flow over or "fall" (e.g., via gravity) over the tubes of the first tube bundle 58A and exchange heat with the cooling fluid induced through the first tube bundle 58A. That is, the liquid refrigerant 98 contacting the first tube bundle 58A absorbs thermal energy from the cooling fluid flowing through the first tube bundle 58A, and the liquid induced into the evaporator 38 via the upper section 110 A portion of the refrigerant 98 can be evaporated. The evaporator 38 can also include a second tube bundle 58B through which a cooling fluid can also be directed, and the second tube bundle 58B can be surrounded by the liquid refrigerant 98 that accumulates within the bottom section 106 of the evaporator 38, and the liquid refrigerant 98 can include the liquid refrigerant 98 directed to the bottom section 106 via the bypass line 100 and / or the liquid refrigerant 98 that falls from the upper section 110 of the evaporator 38 to the bottom section 106. Thus, the second tube bundle 58B can be positioned below the first tube bundle and above the first inlet 107. The second tube bundle 58B can place the liquid refrigerant 98 in a heat exchange relationship with the cooling fluid flowing through the second tube bundle 58B in the bottom section 106 of the evaporator 38 to evaporate a portion of the liquid refrigerant 98 in the bottom section 106. In additional or alternative embodiments, the evaporator 38 can include another suitable type of evaporator instead of a hybrid falling-film and flooded evaporator.

[0029] The illustrated primary line 108 may include an expansion valve 36 that reduces the pressure of the liquid refrigerant 98 flowing through the primary line 108 and regulates the flow of the liquid refrigerant 98 from the first outlet line 102 to the upper section 110 of the evaporator 38 (e.g., regulates the temperature and / or pressure of the liquid refrigerant 98). The bypass line 100 may include a bypass valve 120, and the bypass valve 120 may adjust and / or selectively enable the flow of the liquid refrigerant 98 through the bypass line 100 to the evaporator 38. The expansion valve 36, the expansion valve 66, and / or the bypass valve 120 may be communicatively coupled to the control panel 40, such as a microprocessor 44 of the control panel 40. The microprocessor 44 (e.g., a processing circuit) may be configured to adjust the positions of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 based on, for example, the operating conditions or parameters of the vapor compression system 14 (e.g., feedback received by the control panel 40 as sensor feedback). For example, the memory 46 may include a volatile memory such as a random access memory (RAM) and / or a non-volatile memory such as a read-only memory (ROM), an optical drive, a hard disk drive, a solid state drive, or any other non-transitory computer-readable medium that stores instructions for controlling the operation of the vapor compression system 14, including controlling the operation of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 when executed. The microprocessor 44 (e.g., a processing circuit) may be configured to execute such instructions stored in the memory 46. As an example, the microprocessor 44 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.

[0030] In some embodiments, the vapor compression system 14 may include one or more sensors 122 configured to detect or determine operating parameters of the vapor compression system 14 (e.g., refrigerant pressure, refrigerant temperature, operating capacity). The control panel 40 may be communicatively coupled to the sensors 122 to receive sensor data from the sensors 122, and the control panel 40 may operate based on the sensor data, such as by adjusting the position of the expansion valve 36 and / or the bypass valve 120 (e.g., to open or close). By way of example, the sensor data may indicate the pressure in the evaporator 38, the discharge pressure of the compressor 32, the pressure in the condenser 34, the pressure difference within the vapor compression system 14 (e.g., between the intermediate vessel 70 and the evaporator 38), the level of the liquid refrigerant 96 in the condenser 34, and / or the flow rate of the refrigerant into the evaporator 38 (e.g., via the second inlet 109 of the upper section 110). In fact, the control panel 40 may compare the sensor data to one or more thresholds (e.g., pressure values, pressure difference values, flow rate values) to determine whether any of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 should be adjusted. Further, the sensor data may indicate the respective positions of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120, and thus the control panel 40 may use the sensor data to determine whether the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 are set to the desired positions. For this purpose, the one or more sensors 122 may be coupled to and / or disposed at the compressor 32, the condenser 34, the evaporator 38, the expansion valve 36, the expansion valve 66, the bypass valve 120, the first outlet line 102, the bypass line 100, the primary line 108, any other suitable location of the vapor compression system 14, or any combination thereof.

[0031] As an example, the control panel 40 can adjust the positions of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 to maintain a desired flow of the liquid refrigerant 98 to the evaporator 38. For example, during a low pressure differential state, the control panel 40 can operate to maintain a flow of the liquid refrigerant 98 to the evaporator 38 that exceeds a threshold flow rate. Further, during a state where the pressure differential within the vapor compression system 14 (e.g., the pressure differential between the intermediate vessel 70 and the evaporator 38) fluctuates and affects the drive of the liquid refrigerant 98 through the primary line 108, the control panel 40 can operate to adjust the flow of the liquid refrigerant 98 at a constant or sufficient flow rate in response to the fluctuating pressure differential. The control panel 40 can also adjust the positions of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 to stabilize the levels of the liquid refrigerants 96, 98 within the condenser 34 and / or the intermediate vessel 70, respectively. That is, controlling the flow rate of the liquid refrigerant 98 induced into the evaporator 38 can affect the flow rate of the liquid refrigerant 98 induced from the intermediate vessel 70 and the flow rate of the liquid refrigerant 96 induced from the condenser 34 into the intermediate vessel 70. Thus, the control panel 40 can control the valves 36, 66, 120 based on the flow rates of the liquid refrigerants 96, 98 induced out of the condenser 34 and / or the intermediate vessel 70, respectively, with respect to the flow rates of the refrigerants induced into the condenser 34 and / or the intermediate vessel 70 to control the levels of the liquid refrigerants 96, 98 within the condenser 34 and the intermediate vessel 70, respectively.

[0032] The operation of the control panel 40 can also improve the structural integrity of the components of the vapor compression system 14. By way of example, the control of valves 36, 66, 120 can allow liquid refrigerant 98 to be induced into the evaporator 38 at a desired flow rate without reducing the pressure in the evaporator 38 (e.g., by adjusting the operation of the compressor 32), thereby increasing the pressure difference within the vapor compression system 14 (e.g., between the intermediate vessel 70 and the evaporator 38). Reducing the pressure in the evaporator 38 can cause freezing of the cooling fluid, which can affect the structural integrity of the evaporator 38. Thus, controlling the valves 36, 66, 120 rather than reducing the pressure in the evaporator 38 can prevent freezing of the cooling fluid and thereby improve the structural integrity of the evaporator 38.

[0033] The vapor compression system 14 can also be configured to operate in a free cooling mode to reduce the energy consumption of the vapor compression system 14. By way of example, the control panel 40 can operate the vapor compression system 14 in a free cooling mode in response to the temperature of the conditioning fluid that is induced through the condenser 34 (e.g., to cool the liquid refrigerant 96) being below the ambient temperature and / or a threshold value. As another example, the control panel 40 can operate the vapor compression system 14 in response to the temperature in the condenser 34 (e.g., the conditioning fluid and / or refrigerant temperature) being lower than the temperature in the evaporator 38 (e.g., the cooling fluid and / or refrigerant temperature). In fact, the control of valves 36, 66, 120 can allow liquid refrigerant 98 to be induced into the evaporator 38 at a desired flow rate (e.g., to achieve a desired pressure difference between the intermediate vessel 70 and the evaporator 38) without operating the condenser 34 at an elevated or increased temperature and / or pressure. Thus, the vapor compression system 14 can be configured to operate in a free cooling mode, in which the condenser 34 can be at a reduced temperature and / or pressure and still induce the liquid refrigerant 98 into the evaporator 38 at a desired rate (e.g., without increasing the temperature and / or pressure in the condenser 34).

[0034] During the free cooling mode, the control panel 40 can reduce the power consumption of the compressor 32 by interrupting the operation of the compressor 32 or by operating the compressor 32 at a reduced capacity, thereby reducing the pressurization of the refrigerant entering the condenser 34. In this way, free During the free cooling mode, the pressure differences within the vapor compression system 14 (e.g., between the intermediate vessel 70 and the evaporator 38 and / or between the condenser 34 and the evaporator 38) may be relatively low (e.g., as compared to non-free cooling operation). The bypass line 100 can facilitate the operation of the vapor compression system 14 in the free cooling mode by providing a flow path for the liquid refrigerant 98 to be induced into the evaporator 38 with a limited mechanical force (e.g., the pressure difference created via the compressor 32). For example, the temperature difference between the evaporator 38 and the condenser 34 can drive the vapor refrigerant to flow from the evaporator 38 through the suction line 92, through the compressor 32, through the discharge line 94, and into the condenser 34. The vapor refrigerant then condenses into a liquid via heat exchange with the conditioning fluid and accumulates as the liquid refrigerant 96 within the condenser 34. Thereafter, the liquid refrigerant 96 is induced into the intermediate vessel 70 where the liquid refrigerant 96 partially vaporizes to form vapor refrigerant and partially accumulates as the liquid refrigerant 98.

[0035] When bypass valve 120 is at least partially open, bypass line 100 may allow liquid refrigerant 98 to flow from intermediate container 70 to evaporator 38 via gravity and / or via the pressure within intermediate container 70. In this way, bypass line 100 and bypass valve 120 may allow liquid refrigerant 98 to be properly directed into evaporator 38 through vapor compression system 14 during reduced or interrupted operation of compressor 32 (e.g., during free cooling operation of vapor compression system 14), thereby reducing energy consumption and / or the cost of operating vapor compression system 14. That is, liquid refrigerant 98 directed through bypass line 100 may flow into evaporator 38 without overcoming the gravity that causes it to flow through primary line 108 up to upper section 110 of evaporator 38 along height difference 114. In this way, bypass line 100 extending between intermediate container 70 (e.g., first outlet line 102) and evaporator 38 enables improved operation of vapor compression system 14 (e.g., operation of vapor compression system 14 at higher efficiency).

[0036] FIG. 6 is a schematic diagram of an embodiment of a portion of a vapor compression system 14 illustrating a bypass line 100 extending between a condenser 34 and an evaporator 38 (e.g., a bottom section 106 of the evaporator 38) to enable liquid refrigerant 96 to flow directly from the condenser 34 to the evaporator 38. That is, the bypass line 100 does not extend between the evaporator 38 and the intermediate vessel 70 as shown in FIG. 5, thereby enabling the liquid refrigerant 96 to bypass the intermediate vessel 70. For example, a second outlet line or conduit 140 may extend from an outlet 141 of the condenser 34 (e.g., of a base or bottom section of the condenser 34) to enable the liquid refrigerant 96 to flow out of the condenser 34. Each of the inlet line 68 and the bypass line 100 may extend from the second outlet line 140 and be fluidly coupled to the second outlet line 140. In additional or alternative embodiments, the bypass line 100 and the inlet line 68 may be coupled separately to the condenser 34 (e.g., to separate the outlets of the condenser 34). In any case, a first portion of the liquid refrigerant 96 may flow through the bypass line 100 to the evaporator 38, and a second portion of the liquid refrigerant 96 may flow through the inlet line 68, the intermediate vessel 70, and the primary line 108 to the evaporator 38. In this way, the liquid refrigerant 96 flowing through the bypass line 100 does not flow through the expansion valve 66 to the intermediate vessel 70.

[0037] The vapor compression system 14 illustrated in FIG. 6 may operate in accordance with the techniques described above with respect to FIG. 5. For example, the control panel 40 may operate the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 based on sensor data received from one or more sensors 122, thereby operating the evaporator 38 as a falling film evaporator by opening the expansion valve 66 and the expansion valve 36 to direct the liquid refrigerants 96, 98 to the upper section 110 of the evaporator 38, and / or operating the evaporator 38 as a flooded evaporator by opening the bypass valve 120 to direct the liquid refrigerant 96 to the bottom section 106 of the evaporator 38. Indeed, in some operating modes, the control panel 40 may fully close the expansion valve 36 and / or the expansion valve 66 so that the liquid refrigerants 96, 98 do not reach the upper section It can prevent the inflow into the 110, thereby operating the evaporator 38 as a flooded evaporator. The control panel 40 can also at least partially open the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 to operate the evaporator 38 as a hybrid falling film and flooded evaporator. In other words, the control panel 40 controls the operation of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 to enable a desired flow rate of the liquid refrigerant 96 and / or 98 to the evaporator 38 through the first inlet 107 and / or the second inlet 108 (e.g., based on feedback from one or more sensors 122).

[0038] FIG. 7 is a schematic view of an embodiment of a part of the vapor compression system 14, illustrating a bypass line 100 extending between the first outlet line 102 and a side section or portion 160 of the evaporator 38 (e.g., the third inlet 161 of the side section 160). For example, the positioning of the intermediate container 70 relative to the evaporator 38 and / or the pressure difference within the vapor compression system 14 (e.g., between the intermediate container 70 and the evaporator 38) can allow the liquid refrigerant 98 to flow into the side section 160 instead of the bottom section 106 of the evaporator 38 that is below the side section 160 relative to the vertical axis 112. That is, although the gravity and / or pressure difference within the vapor compression system 14 can allow the liquid refrigerant 98 to flow into the evaporator 38 at a greater flow rate through the bottom section 106 compared to through the side section 160, this implementation of the vapor compression system 14 can allow the liquid refrigerant 98 to flow into the evaporator 38 at a desired flow rate through the side section 160 (e.g., without the liquid refrigerant 98 flowing into the evaporator 38 at an increased flow rate through the bottom section 106).

[0039] The liquid refrigerant 98 flowing through the bypass line 100 and into the evaporator 38 via the side section 161 may flow over a part or subset of the first tube bundle 58A in the upper section 110, enabling the evaporator 38 to operate partially as a falling-film evaporator. Further, the liquid refrigerant 98 induced into the evaporator 38 accumulates in the bottom section 106 of the evaporator 38, at least partially surrounding the second tube bundle 58B of the evaporator 38 in the bottom section 106, enabling the evaporator 38 to operate as a flooded evaporator. Thus, inducing the liquid refrigerant 98 into the evaporator 38 via the bypass line 100 fluidly coupled to the side section 160 may enable the evaporator 38 to operate as both a falling-film evaporator and a flooded evaporator. In some embodiments, the configuration of the bypass line 100 shown in FIG. 7 may avoid inducing the liquid refrigerant 98 into the evaporator 38 in an upward direction (e.g., along the vertical axis 112, against gravity), and may further reduce the flow resistance of the liquid refrigerant 98 into the evaporator 38. Further, the control panel 40 may operate the illustrated vapor compression system 14 using the techniques described above, such as operating the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 based on sensor data received from one or more sensors 122.

[0040] FIG. 8 is a flowchart of an embodiment of a method or process 180 for operating the vapor compression system 14 according to the techniques of the present disclosure. As an example, one or more control systems (e.g., the control panel 40) or processing circuits may be configured to execute the steps of the method 180 (e.g., via instructions stored in the memory 46). Note that the method 180 may be executed differently in alternative embodiments. For example, additional steps may be executed, and / or certain steps of the illustrated method 180 may be removed, modified, and / or executed in a different order.

[0041] In block 182, one or more operating parameters indicating a pressure difference within the vapor compression system 14 are received. For example, the one or more operating parameters may be received via sensor data output by one or more sensors 122. As an example, the one or more operating parameters may include the pressure difference between the evaporator 38 and the intermediate vessel 70 and / or between the evaporator 38 and the condenser 34. As another example, the one or more operating parameters may include the liquid level of the refrigerant (e.g., liquid refrigerants 96, 98, vapor refrigerant) within the intermediate vessel 70, within the condenser 34, within the evaporator 38, and / or within the primary line 108, the respective pressures within the condenser 34, the evaporator 38, the discharge line 94, and / or the intermediate vessel 70, the flow rate and / or pressure of the liquid refrigerant 98 within the primary line 108, the flow rate of the liquid refrigerant 96 through the inlet line 68, the amount of electrical power supplied to the compressor (e.g., compressor 32), the speed of the compressor, the respective temperatures within the condenser 34, the evaporator 38, and / or the intermediate vessel 70, the ambient temperature, the temperature of the cooling fluid within the evaporator 38, the temperature of the regulating fluid within the condenser 34, another suitable operating parameter, or any combination thereof. In practice, the one or more operating parameters may indicate whether the liquid refrigerant 98 is flowing into the evaporator 38 at a desired or target flow rate. In block 184, the one or more operating parameters are compared to a threshold value. The comparison of the one or more operating parameters to the threshold value may indicate whether the operation of the vapor compression system 14 should be adjusted.

[0042] In block 186, the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 are operated (e.g., adjusted) based on a comparison of one or more operating parameters with a threshold value. For example, the respective target or desired position of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 can be determined based on a comparison of one or more operating parameters with a threshold value. In certain embodiments, any or all of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 can include an on / off valve configured to transition between a fully open position and a fully closed position. In additional or alternative embodiments, any or all of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 can also be configured to transition to an intermediate position between the fully open position and the fully closed position, such as a partially open position or a partially closed position. For example, the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 can be an electromagnetic valve, and the respective position of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 can be based on a received control signal (e.g., from the control panel 40). In any case, using sensor data indicative of the respective position of the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 (e.g., by the control panel 40), the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 can be adjusted to a corresponding target position to enable a desired flow of the liquid refrigerants 96, 98 into the evaporator 38.

[0043] As an example, when the comparison of one or more operating parameters with a threshold indicates that the pressure difference (e.g., between the condenser 34 and the evaporator 38) is low (e.g., below a low threshold pressure difference), the vapor compression system 14 (e.g., the expansion valve 36, the expansion valve 66, and / or the bypass valve 120) can be operated to increase the flow of the liquid refrigerants 96, 98 into the evaporator 38 by increasing the opening of the bypass valve 120 and / or by decreasing the opening of the expansion valve 36, etc. Similarly, when the comparison of one or more operating parameters with a threshold indicates that the pressure difference is high (e.g., above a high threshold pressure difference), the vapor compression system 14 (e.g., the expansion valve 36, the expansion valve 66, and / or the bypass valve 120) can be operated to decrease the flow of the refrigerant into the evaporator 38 via the bypass line 100 by decreasing the opening of the bypass valve 120 and / or by increasing the opening of the expansion valve 36, etc.

[0044] In some embodiments, the position of the expansion valve 36 and / or the expansion valve 66 can be adjusted before adjusting the position of the bypass valve 120. For example, the position of the expansion valve 36 and / or the position of the expansion valve 66 can be adjusted to their respective threshold positions (e.g., fully open position, fully closed position) before the bypass valve 120 is adjusted. In other words, the bypass valve 120 may not be adjusted until the expansion valve 36 and / or the expansion valve 66 are fully or completely opened or fully or completely closed. For example, the by The bypass valve 120 can remain closed until the expansion valve 36 and / or the expansion valve 66 is in a fully open position. After the expansion valve 36 and / or the expansion valve 66 is adjusted to the fully open position, then the bypass valve 120 can be opened in increments (e.g., 20% of the fully open size) set at time intervals. In additional or alternative embodiments, the expansion valve 36, the expansion valve 66, and / or the bypass valve 120 can be adjusted simultaneously, such as to allow a desired balance of the flow of the liquid refrigerants 96, 98 into the evaporator 38 via the first inlet 107 and the second inlet 108. For example, the openings of the expansion valve 36 and / or the expansion valve 66 can be reduced while the opening of the bypass valve 120 increases to increase the refrigerant flowing into the evaporator 38 through the bypass line 100 (e.g., rather than through the primary line 108).

[0045] The present disclosure can provide one or more technical effects for enabling improved operation of an HVAC system. For example, the HVAC system can include a vapor compression system configured to circulate a refrigerant. The vapor compression system can include a condenser configured to cool the refrigerant via heat exchange with a conditioning fluid, and an evaporator configured to cool a cooling fluid in a heat exchange relationship with the cooled refrigerant. The vapor compression system can also include an intermediate vessel that further cools the liquid refrigerant discharged from the condenser and directs the liquid refrigerant to the evaporator. The vapor compression system can include a primary line configured to direct the refrigerant from the intermediate vessel into the evaporator, and a bypass line configured to direct the refrigerant into the evaporator (e.g., from the condenser, from the intermediate vessel).

[0046] The bypass line may provide less resistance to the flow of refrigerant into the evaporator than the primary line. For example, the primary line may utilize the pressure differential within the vapor compression system (e.g., between the condenser and the evaporator and / or between the intermediate vessel and the evaporator) to direct refrigerant into the evaporator, and the bypass line may utilize gravity to direct refrigerant into the evaporator. In some embodiments, the bypass line enables the flow of refrigerant into the evaporator by the refrigerant overcoming less gravity, and / or no gravity, than the refrigerant directed into the evaporator via the primary line. Thus, for example, during certain operating conditions such as when the refrigerant is not being directed into the evaporator at a target or desired flow rate via the primary line, and / or during low pressure differential conditions in the vapor compression system, the bypass line (e.g., the bypass valve of the bypass line) may be operated to increase the flow rate of refrigerant into the evaporator via the bypass line towards the target flow rate. The techniques of the present disclosure may also be utilized in additional or alternative operating conditions of the vapor compression system such as during periods of liquid refrigerant stagnation within the vapor compression system (e.g., within the primary line), during fluctuations in the head or discharge pressure, during fluctuations in the liquid refrigerant level within the condenser, etc. It should be noted that the technical effects and technical problems herein are examples and are not limiting. The embodiments described herein may have other technical effects and may solve other technical problems.

[0047] Only certain features and embodiments of this disclosure have been illustrated and described, but many modifications and variations (e.g., changes in the size, dimensions, structure, shape and ratio of various elements, values of parameters (e.g., temperature, pressure), mounting arrangements, use of materials, color, orientation) may occur to those skilled in the art 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 changed or re-ordered according to alternative embodiments. Therefore, it should be noted that the appended claims are intended to cover all such modifications and variations as falling within the true spirit of this disclosure. Further, in order to provide a concise description of the exemplary embodiments, not all features of actual implementations may be described (i.e., those not relevant to the presently contemplated best mode for carrying out the disclosure or not relevant to enabling the claimed embodiments). As in any engineering or design project, many implementation-specific decisions may be made in the development of any such actual implementation, which should be understood. Such development efforts may be complex and time-consuming, but nevertheless will be routine work of design, fabrication, and manufacture for those skilled in the art who benefit from this disclosure without undue experimentation.

[0048] The techniques presented and claimed herein are referred to and applicable to material objects and specific examples of a practical nature that clearly improve the art, and thus are not abstract, intangible, or purely theoretical. Further, if any of the appended claims at the end of this specification includes one or more elements designated as "means for [performing a function]" or "steps for [performing a function]", such elements are intended to be construed in accordance with 35 U.S.C. §112(f). However, for any claims that include elements designated in other ways, such elements are not intended to be construed in accordance with 35 U.S.C. §112(f).

Claims

1. A heating, ventilation, and / or air conditioning (HVAC) system, comprising: a container configured to receive refrigerant from a condenser of the HVAC system; an evaporator configured to receive the refrigerant from the container; a first conduit configured to direct a first flow of the refrigerant to a first inlet of the evaporator; a second conduit configured to direct a second flow of the refrigerant to a second inlet of the evaporator, wherein the second inlet is above the first inlet with respect to a vertical axis.

2. The HVAC system of claim 1, further comprising a third conduit extending from the condenser to the container, the third conduit comprising an expansion valve configured to reduce the pressure of the refrigerant directed from the condenser to the container to enable separation of the refrigerant into liquid refrigerant and vapor refrigerant within the container.

3. The HVAC system of claim 2, further comprising an outlet conduit extending from the container and configured to direct the liquid refrigerant from the container toward the evaporator, wherein each of the first conduit and the second conduit extends from the outlet conduit.

4. The HVAC system of claim 2, further comprising: an outlet conduit configured to discharge the refrigerant from the condenser; and an inlet conduit extending from the outlet conduit to the container, wherein the first conduit extends from the outlet conduit to the evaporator to enable bypassing of the refrigerant in the container, and the second conduit extends from the container to the evaporator.

5. The HVAC system of claim 1, wherein the first conduit comprises a bypass valve, and the HVAC system further comprises a controller communicatively coupled to the bypass valve, the controller being configured to operate the bypass valve based on an operating parameter indicative of a pressure differential within the HVAC system.

6. The HVAC system of claim 1, wherein the first inlet is disposed in a bottom section of the evaporator.

7. The HVAC system of claim 1, wherein the evaporator is a hybrid falling-film and flooded evaporator.

8. A heating, ventilation, and / or air conditioning (HVAC) system, comprising: a container configured to receive refrigerant from a condenser and to separate the refrigerant received from the condenser into vapor refrigerant and liquid refrigerant; A first conduit configured to direct a first flow of liquid refrigerant to a first inlet of an evaporator of the HVAC system, the first conduit comprising a first conduit having a bypass valve; A second conduit configured to direct a second flow of liquid refrigerant to a second inlet of the evaporator, the second inlet being above the first inlet with respect to a vertical axis, the second conduit; A controller communicatively coupled to the bypass valve, the controller being configured to operate the bypass valve to control the flow rate of the first flow of liquid refrigerant to the evaporator via the first conduit, a heating, ventilation, and / or air conditioning (HVAC) system comprising: **Claim 9** The HVAC system according to claim 8, comprising the evaporator, the second conduit extending to an upper section of the evaporator, the controller being configured to close the bypass valve and operate the evaporator as a falling film evaporator. **Claim 10** The HVAC system according to claim 8, comprising the evaporator, the second conduit comprising an expansion valve configured to reduce the pressure of the second flow of liquid refrigerant directed through the second conduit, the first conduit extending to a bottom section of the evaporator, the controller being configured to close the expansion valve and operate the evaporator as a flooded evaporator. **Claim 11** The HVAC system according to claim 8, wherein the controller is configured to operate the bypass valve based on an operating parameter indicative of the level of the liquid refrigerant in the container, the liquid level of the refrigerant in the condenser, the liquid level of the refrigerant in the evaporator, the level of the second flow of liquid refrigerant in the second conduit, the pressure in the condenser, the pressure in the evaporator, the pressure in the container, the flow rate of the second flow of liquid refrigerant through the second conduit, the temperature in the condenser, the temperature in the evaporator, the temperature in the container, the ambient temperature, the amount of power supplied to the compressor of the HVAC system, the speed of the compressor, or any combination thereof. **Claim 12** The HVAC system according to claim 8, comprising the condenser and the compressor, the compressor being configured to receive refrigerant from the evaporator, pressurize the refrigerant, and direct the refrigerant to the condenser. **Claim 13** The HVAC system according to claim 12, wherein the controller is configured to interrupt the operation of the compressor or operate the compressor at a reduced capacity based on the temperature in the condenser that is below a threshold value.

14. The compressor is a first compressor configured to receive a vapor refrigerant from the container, pressurize the vapor refrigerant, and direct the pressurized vapor refrigerant to the condenser, and the HVAC system includes a second compressor configured to receive a vapor refrigerant from the container, pressurize the vapor refrigerant, and direct the pressurized vapor refrigerant to the condenser. The HVAC system according to claim 12.

15. A heating, ventilation, and / or air conditioning (HVAC) system, a condenser, an intermediate container configured to receive a refrigerant from the condenser, an evaporator configured to receive the refrigerant from the intermediate container, a first conduit extending between the condenser and the intermediate container, the first conduit including an expansion valve configured to reduce the pressure of the refrigerant directed through the first conduit to enable separation of the refrigerant into liquid refrigerant and vapor refrigerant within the intermediate container. A first conduit, a second conduit extending between the intermediate container and a first inlet of the evaporator, the second conduit being configured to direct the liquid refrigerant into the evaporator through the first inlet. A second conduit, a third conduit extending between the intermediate container and a second inlet of the evaporator, the second inlet being above the first inlet with respect to a vertical axis, the third conduit being configured to direct the liquid refrigerant into the evaporator through the second inlet. A heating, ventilation, and / or air conditioning (HVAC) system comprising a third conduit.

16. The HVAC system according to claim 15, wherein the second conduit includes a bypass valve configured to control the flow rate of the liquid refrigerant directed through the second conduit, and the third conduit includes an additional expansion valve configured to reduce the pressure of the liquid refrigerant directed through the third conduit.

17. An HVAC system according to claim 16, comprising a controller communicatively coupled to the expansion valve, the additional expansion valve, and the bypass valve, the controller configured to control the expansion valve, the additional expansion valve, the bypass valve, or any combination thereof based on an operating parameter indicative of a flow rate of the liquid refrigerant into the evaporator.

18. An HVAC system according to claim 15, comprising a fourth conduit configured to discharge the liquid refrigerant from the intermediate container, each of the second conduit and the third conduit extending between the fourth conduit and the evaporator.

19. An HVAC system according to claim 15, wherein the second inlet is disposed in a side section of the evaporator.

20. An HVAC system according to claim 15, wherein the first inlet is positioned below a tube bundle in the evaporator with respect to the vertical axis, and the second inlet is positioned above the tube bundle with respect to the vertical axis.

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