Heating, ventilation, air conditioning and / or refrigeration (HVACR) system and control method thereof

Abstract

A heating, ventilation, air conditioning and / or cooling (HVACamp; a refrigeration system (R, R) includes a refrigeration circuit having an evaporator, a compressor, and a condenser that circulates a refrigerant and facilitates heat exchange between the refrigerant and a conditioning fluid. A pre-swirl vane (PRV) is located at an inlet of the compressor, a variable geometry diffuser (VGD) is located at an outlet of the compressor, or both. Control circuitry selectively operates the HVACamp in a normal cooling mode or a natural cooling mode; r system. In the normal cooling mode, the control circuitry controls the compressor to be in an active state to compress the refrigerant. In the natural cooling mode, the control circuitry controls the compressor in an inactive state such that the refrigerant is circulated through the compressor via a pressure differential generator. The control circuitry adjusts the PRV, the VGD, or both to control the HVACamp in the natural cooling mode; r, cooling capacity of the system.

Description

[0001] Cross-reference to related applications This application claims priority and benefit to U.S. Provisional Patent Application No. 63 / 529,112, filed July 26, 2023, the entire contents of which are incorporated herein by reference for all purposes. Background Technology

[0002] This disclosure generally relates to heating, ventilation, air conditioning and / or cooling (HVAC&R) systems. More specifically, this disclosure relates to capacity control for HVAC&R systems operating in natural cooling / heating mode.

[0003] HVAC&R systems have numerous applications, including residential, commercial, and industrial applications. For example, commercial HVAC&R systems can be used to cool or heat enclosed spaces. Very generally, an HVAC&R system may comprise a closed loop between an evaporator that circulates fluid through which the fluid absorbs heat and a condenser that releases heat from the fluid. The fluid flowing within this closed loop is typically configured to undergo a phase change within the system's normal operating temperatures and pressures, allowing a significant amount of heat to be exchanged using the fluid's latent heat of vaporization.

[0004] In applications where HVAC&R systems are used for cooling, they can operate in natural cooling mode when the ambient temperature is low. In natural cooling mode, cooling is provided using the low ambient temperature without requiring additional energy input from sources such as compressors. Similarly, in applications where HVAC&R systems are used for heating, they can operate in natural heating mode when the ambient temperature is high. In natural heating mode, heating is provided using the high ambient temperature without requiring additional energy input. While utilizing ambient temperature in natural cooling / heating modes improves the efficiency of HVAC&R operation, the ambient temperature may not always remain constant, and this can therefore affect the cooling / heating capacity of the HVAC&R system. However, controlling the amount of cooling / heating provided during natural cooling / heating modes in an HVAC&R system can be challenging.

[0005] In light of the foregoing, it is now recognized that the cooling / heating capacity of HVAC&R systems needs to be controlled according to ambient temperature. Summary of the Invention

[0006] In this embodiment, the heating, ventilation, air conditioning, and / or cooling (HVAC&R) system includes a refrigeration circuit with an evaporator, a compressor, and a condenser, which circulates refrigerant and facilitates heat exchange between the refrigerant and the conditioning fluid. A pre-rotating vane (PRV) is located at the compressor inlet, and a variable geometry diffuser (VGD) is located at the compressor outlet, or both. The control circuitry selectively operates the HVAC&R system in either a conventional cooling mode or a natural cooling mode. In conventional cooling mode, the control circuitry keeps the compressor active to compress the refrigerant. In natural cooling mode, the control circuitry keeps the compressor inactive, allowing refrigerant to circulate through the compressor via a pressure differential generator. The control circuitry adjusts the PRV, VGD, or both to control the cooling capacity of the HVAC&R system in natural cooling mode.

[0007] In one embodiment, a method is provided for controlling a heating, ventilation, air conditioning, and / or cooling (HVAC&R) system, the HVAC&R system including a refrigeration circuit comprising an evaporator, a compressor, and a condenser, the condenser being configured to circulate refrigerant and facilitate heat exchange between the refrigerant and a conditioning fluid. The method includes selectively operating the HVAC&R system in a conventional cooling mode or a natural cooling mode via a control circuit system. In natural cooling mode, the compressor's compression operation is inactive, and refrigerant circulates through the compressor. In conventional cooling mode, the compressor's compression operation is active, and refrigerant is actuated by the compressor through the refrigerant circuit. The method includes adjusting a pre-rotating vane (PRV) and / or a variable geometry diffuser (VGD) via the control circuit system to control the cooling capacity of the HVAC&R system in natural cooling mode, the PRV being located at the compressor inlet.

[0008] In one embodiment, a heating, ventilation, air conditioning, and / or cooling (HVAC&R) system includes a compressor comprising a pre-rotating vane (PRV) at the compressor inlet and a variable geometry diffuser (VGD) at the compressor outlet, or both a pre-rotating vane and a variable geometry diffuser. A control circuitry system selectively operates the HVAC&R system in either a conventional heating mode or a natural heating mode. In natural heating mode, the control circuitry system is configured to keep the compressor inactive, allowing refrigerant to circulate through the compressor via a pressure differential generator. In conventional heating mode, the control circuitry is configured to keep the compressor active, allowing refrigerant to circulate through the compressor. The control circuitry is configured to adjust the PRV, VGD, or both to control the heating capacity of the HVAC&R system in natural heating mode. Attached Figure Description

[0009] The various objects, aspects, features, and advantages of this disclosure will become more apparent and better understood through a detailed description taken in conjunction with the accompanying drawings, throughout which similar reference numerals identify corresponding elements. In the drawings, the same reference numerals generally denote identical, functionally similar, and / or structurally similar elements.

[0010] Figure 1 This is a perspective view of an environment for a heating, ventilation, air conditioning and / or cooling (HVAC&R) system in a building for a typical commercial environment, according to embodiments of the present disclosure. Figure 2 It is possible to implement the embodiments according to this disclosure. Figure 1 A block diagram of the vapor compression system used in an HVAC&R system; Figure 3 This is a block diagram of a vapor compression system having an intermediate loop combined between a condenser and an expansion device, according to an embodiment of the present disclosure. Figure 4 This illustrates an embodiment of the present disclosure that can be implemented... Figure 1 A block diagram of an exemplary embodiment of a vapor compression system used in an HVAC&R system; Figure 5 Driven by an electric motor according to embodiments of this disclosure Figure 4 A perspective view of the compressor; Figure 6A This is an embodiment of the present disclosure operating in conventional cooling mode. Figure 4 A block diagram of a vapor compression system; Figure 6B This is an embodiment of the present disclosure operating in natural cooling mode. Figure 4 A block diagram of a vapor compression system; Figure 7A and Figure 7B It is possible to implement the embodiments according to this disclosure. Figure 1 A block diagram of the vapor compression system used in an HVAC&R system; Figure 8 This is a flowchart of a method for controlling the cooling capacity of an HVAC&R system (e.g., a cooler) operating in natural cooling mode, according to embodiments of the present disclosure. Figure 9 This is a flowchart of a method for controlling the heating capacity of an HVAC&R system (e.g., a boiler) operating in natural heating mode, according to embodiments of the present disclosure. Figure 10A and Figure 10B The flowcharts are of a method for controlling the cooling capacity of an HVAC&R system (e.g., a heat pump) during natural cooling and natural heating modes according to embodiments of the present disclosure; and Figure 11 This is a flowchart of a method for preventing conditioning fluid from freezing in the evaporator of an HVAC&R system according to embodiments of the present disclosure. Detailed Implementation

[0011] One or more specific embodiments will be described below. To provide a concise description of these embodiments, not all features of the actual embodiments are described in the specification. It should be understood that in the development of any such actual embodiment, as in any engineering or design project, many embodiment-specific decisions must be made to achieve the developer's specific goals, such as complying with system-related and business-related constraints, which may vary from embodiment to embodiment. Furthermore, it should be understood that such development work may be complex and time-consuming, but is merely a routine task of design, manufacture, and production for those skilled in the art who benefit from this disclosure.

[0012] In describing the elements of various embodiments of this disclosure, the articles “a” and “the” are intended to mean the presence of one or more of the element. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that additional elements may be present in addition to those listed. Furthermore, it should be understood that references to “one embodiment” or “embodiment” in this disclosure are not intended to exclude the existence of additional embodiments incorporated into the described features.

[0013] Embodiments of this disclosure relate to a heating, ventilation, air conditioning, and / or cooling (HVAC&R) system configured to cool a conditioning fluid. In some embodiments, the HVAC&R system may include a refrigeration circuit having an evaporator, a compressor, and a condenser, which may be used to cool or heat the conditioning fluid (e.g., air). For example, the HVAC&R system may receive the conditioning fluid (e.g., air) from the environment and may cool the conditioning fluid via heat exchange with refrigerant within the refrigeration circuit. Further, the HVAC&R system may then return or supply the cooled conditioning fluid to a structure (e.g., a building) for cooling. Specifically, for example, a pressure drop may be created in the refrigerant via a compressor and an expansion valve to lower the temperature of the refrigerant. The evaporator may be configured to allow the low-temperature refrigerant to exchange heat with the conditioning fluid to absorb heat or thermal energy from the conditioning fluid, thereby cooling the conditioning fluid. Subsequently, the refrigerant may be pressurized by the compressor, which increases the temperature of the refrigerant. The condenser may then be used to exchange heat between the higher-temperature refrigerant and the environment.

[0014] In some cases, the ambient temperature may be very low. Therefore, the temperature of the cooling fluid (e.g., outdoor air) that exchanges heat with the refrigerant in the condenser may be below or equal to a preset threshold temperature. In such scenarios, embodiments of the HVAC&R system disclosed herein can operate in a natural cooling mode. In natural cooling mode, the compressor is stopped (e.g., the compressor motor is stopped) to cease compressor operation, and the refrigerant continues to circulate through the refrigeration circuit. Continuous refrigerant circulation can be achieved with or without a pump (e.g., an additional liquid pump) (e.g., by thermosiphon operation). When the HVAC&R system operates in natural cooling mode, the cooling capacity of the HVAC&R system can be controlled (e.g., decreased or increased) according to cooling demand. To control the cooling capacity, the pre-rotating vane (PRV) and / or variable geometry diffuser (VGD) can be adjusted between a fully open position and a fully closed position. For example, the cooling capacity can be gradually reduced by progressively driving one or both of the PRV and VGD from a corresponding fully or partially open position toward or to a corresponding fully closed position. Similarly, the cooling capacity can be gradually increased by gradually driving one or both of the PRV and VGD from the corresponding fully or partially closed position toward or to the corresponding fully open position. According to this embodiment, when the desired cooling capacity is achieved, the adjustment of one or both of the PRV and VGD can be stopped, and the PRV and / or VGD can then be held in that position until it is desired to change the cooling capacity again.

[0015] In embodiments of this disclosure, the HVAC&R system is configured to heat a conditioning fluid to warm the environment. For example, the HVAC&R system may operate as a heat pump, receiving a conditioning fluid, heating the conditioning fluid, and then returning or supplying the heated conditioning fluid to a structure (e.g., a building). In some embodiments, the HVAC&R system may include a refrigeration circuit having an evaporator, a compressor, and a condenser. The compressor may include a pre-rotating vane (PRV) at its inlet and / or a geometrically variable diffuser (VGD) at its outlet. In such a heating configuration, the condenser may be arranged to allow the refrigerant to exchange heat with the conditioning fluid to release heat or thermal energy into the conditioning fluid, thereby heating the conditioning fluid. In some cases, the ambient temperature may be high. Therefore, the temperature of the heated fluid that is in heat exchange with the refrigerant in the evaporator may be higher than or equal to a preset threshold temperature. In such a scenario, the HVAC&R system may operate in a natural heating mode according to this embodiment. In natural heating mode, the compressor stops (e.g., the compressor motor stops) to terminate the compressor's compression operation, and the refrigerant continues to circulate through the refrigeration circuit. This continuous circulation of refrigerant can be achieved with or without a pump (e.g., an additional liquid pump) (e.g., via thermosiphon operation). When the HVAC&R system operates in natural heating mode, the heating capacity of the HVAC&R system can be controlled (e.g., decreased or increased) according to heating demand. To control the heating capacity, one or both of the PRV and VGD can be adjusted between a corresponding fully or partially open position and a corresponding fully closed position. For example, the heating capacity can be gradually decreased by gradually driving one or both of the PRV and VGD from a corresponding fully open position to a corresponding fully closed position. Similarly, the heating capacity can be gradually increased by gradually driving one or both of the PRV and VGD from a corresponding fully or partially closed position toward or to a corresponding fully open position. According to this embodiment, when the heating demand of the HVAC&R system is met, the adjustment of one or both of the PRV and VGD can be stopped, and the PRV and / or VGD can remain in the stated position until it is desired to change the heating capacity again.

[0016] Before turning to the accompanying drawings, it should be understood that this disclosure is not limited to the details or methods set forth in the specification or shown in the drawings. It should also be understood that the terminology provided in the specification and drawings is for descriptive purposes only and should not be considered limiting. Generally, the drawings depict methods and systems for controlling the capacity of HVAC&R systems operating in natural cooling / heating mode.

[0017] Now turn to the attached image. Figure 1This is a perspective view of the environment of a heating, ventilation, air conditioning, and / or cooling (HVAC&R) system 10 in a building 12 for a typical commercial environment, according to some embodiments of this disclosure. The HVAC&R system 10 may employ one or more HVAC&R units for building environmental management. As used herein, an HVAC&R system includes any number of components configured to enable the adjustment of parameters related to climate characteristics, such as temperature, humidity, airflow, pressure, air quality, etc. For example, the term "HVAC&R system" as used herein is defined as conventionally understood and as further described herein. Components or parts of an "HVAC&R system" may include, but are not limited to, all, some, or individual parts of components such as heat exchangers, heaters, airflow control devices (such as fans), sensors configured to detect climate characteristics or operating parameters, filters, control devices configured to regulate the operation of HVAC&R system components, components configured to regulate climate characteristics, or combinations thereof. An "HVAC&R system" is a system configured to provide functions such as heating, cooling, ventilation, dehumidification, pressurization, refrigeration, filtration, or any combination thereof. The embodiments described herein can be used in a variety of applications to control climate characteristics, such as residential, commercial, industrial, transportation, or other applications that require climate control.

[0018] HVAC&R system 10 may include one or more HVAC&R units 14 and 16, which are operable to generate temperature-controlled air to be supplied to the interior spaces within building 12. In some embodiments, HVAC&R unit 14 may be a vapor compression system 14 (e.g., a cooler, a chiller system) that supplies a cooling liquid, which may be used to cool building 12. In some embodiments, HVAC&R unit 16 may be a boiler 16 for supplying a warm liquid to heat building 12 and an air distribution system for circulating air through building 12. The air distribution system may also include a return air duct 18, a supply air duct 20, and / or an air handler 22. In some embodiments, air handler 22 may include a heat exchanger connected to HVAC&R units 14 and 16 via duct 24. In some other embodiments, the HVAC&R units in HVAC&R system 10 may be heat pumps that utilize a refrigeration loop configured to operate in different modes to provide both heating and cooling to building 12.

[0019] Depending on the operating mode of the HVAC&R system 10, the heat exchanger in the air handler 22 can receive heated liquid from the boiler 16 or cooled liquid from the vapor compression system 14. The HVAC&R system 10 is shown as having a separate air handler on each floor of the building 12, but in other embodiments, the HVAC&R system 10 may include the air handler 22 and / or other components that may be shared between floors.

[0020] Figure 2 This is a block diagram of a vapor compression system 14 (e.g., a vapor compression circuit) that can be used in an HVAC&R system 10 according to some embodiments of the present disclosure. The vapor compression system 14 can circulate refrigerant through a refrigeration circuit 30 that begins with a compressor 32. The refrigeration circuit 30 may also include a condenser 34, an expansion valve or device 36, and a liquid cooler or evaporator 38. The vapor compression system 14 may further include a control panel 40 having an analog-to-digital (AD) converter 42, a microprocessor 44, non-volatile memory 46, and / or an interface board 48.

[0021] Examples of fluids that can be used as a refrigerant (e.g., working fluid) in the vapor compression system 14 may include, but are not limited to: hydrofluorocarbon (HFC) based refrigerants such as R-410A, R-407, R-134a, R-1234ze, Rl233zd, hydrofluoroolefins (HFO), “natural” refrigerants such as 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 effectively utilize a refrigerant with a standard boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere, which is also referred to as a low-pressure refrigerant relative to medium-pressure refrigerants such as R-134a. As used herein, “standard boiling point” may refer to the boiling point temperature measured at one atmosphere.

[0022] In some embodiments, the vapor compression system 14 may use one or more of a motor 50, a variable speed drive (VSD) 52, 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 the VSD 52. The VSD 52 receives AC power with a specific fixed line voltage and fixed line frequency from an alternating current (AC) power source and supplies power with a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be directly powered by 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 by an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically rectified permanent magnet motor, or another suitable motor. Although the motor 50 is shown as being driven by a VSD, the scope of this disclosure is not limited thereto. In some other embodiments, a constant speed motor drive may be used to drive the motor 50 without departing from the scope of this disclosure.

[0023] Compressor 32 compresses working fluid vapor and delivers it to condenser 34 through a discharge passage. In some embodiments, compressor 32 may be a centrifugal compressor. The working fluid vapor delivered by compressor 32 to condenser 34 can transfer heat to a cooling fluid (e.g., water or air) in condenser 34. Due to the heat transfer with the cooling fluid, the working fluid vapor can condense into working fluid liquid in condenser 34. The liquid working fluid from condenser 34 can flow to evaporator 38 through expansion device 36. Figure 2 In the illustrated embodiment, the condenser 34 is water-cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies cooling fluid to the condenser 34.

[0024] The liquid working fluid delivered to evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in condenser 34. The liquid working fluid in evaporator 38 may undergo a phase change from liquid working fluid to working fluid vapor. For example... Figure 2 As shown in the illustrated embodiment, 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. Cooling fluid (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via the return line 60R and exits the evaporator 38 via the supply line 60S. The evaporator 38 may reduce the temperature of the cooling fluid in the tube bundle 58 via heat transfer with the working fluid. The tube bundle 58 in the evaporator 38 may comprise multiple tubes and / or multiple tube bundles. In any case, the steam working fluid exits the evaporator 38 and returns to the compressor 32 via the suction line to complete the cycle.

[0025] Figure 3 This is a block diagram illustrating a vapor compression system 14 according to some other embodiments of the present disclosure, having an intermediate loop 64 coupled between a condenser 34 and an expansion device 36. The intermediate loop 64 may have an inlet line 68 (e.g., a conduit) directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly connected to the condenser 34. Figure 3 As shown in the illustrated embodiment, the inlet line 68 includes a first expansion device 66 positioned upstream of the intermediate container 70. In some embodiments, the intermediate container 70 may be a flash tank (e.g., a flash intercooler, an energy saver). In other embodiments, the intermediate container 70 may be configured as a heat exchanger or a "surface energy saver". Figure 3 In the illustrated embodiment, the intermediate container 70 serves as a flash tank, and the first expansion device 66 is configured to reduce the pressure of the liquid working fluid received from the condenser 34 (e.g., to expand the liquid working fluid). During the expansion process, a portion of the liquid may evaporate, and thus the intermediate container 70 can be used to separate the vapor from the liquid received from the first expansion device 66.

[0026] Additionally, the intermediate container 70 provides further expansion of the liquid working fluid due to the pressure drop it experiences upon entering the intermediate container 70 (e.g., due to the rapid increase in volume experienced upon entering the intermediate container 70). Vapor in the intermediate container 70 can be drawn in by the compressor 32 through its suction line 74 (e.g., a conduit). In other embodiments, vapor in the intermediate container can be drawn into an intermediate stage (e.g., a non-suction stage) of the compressor 32. Due to the expansion device 66 and / or the expansion in the intermediate container 70, the liquid collected in the intermediate container 70 may have a lower enthalpy than the liquid refrigerant leaving the condenser 34. The liquid from the intermediate container 70 can then flow through line 72 (e.g., a conduit) and through the second expansion device 36 to the evaporator 38.

[0027] It should be understood that any features described herein can be combined with vapor compression system 14 or any other suitable HVAC&R system. For example, this technology can be combined with any HVAC&R system having an economizer (such as intermediate container 70) and a compressor (such as compressor 32). HVAC&R systems incorporating this technology may include water-cooled refrigerators, air-cooled refrigerators, heat pumps, and / or any other suitable HVAC&R system. The HVAC&R system may utilize any suitable working fluid, such as one or more of the refrigerants discussed above, or another working fluid.

[0028] Figure 4This is a block diagram of an exemplary embodiment of a vapor compression system 400 that can be used in an HVAC&R system 10 according to an embodiment of the present disclosure. Figure 1 The vapor compression system 14 can be used Figure 4 The vapor compression system 400 shown is used for implementation. The vapor compression system 400 can operate in a conventional cooling mode or a natural cooling mode based on ambient temperature conditions. Specifically, the vapor compression system 400 may include a control circuit system configured to selectively operate the vapor compression system 400 in a conventional cooling mode or a natural cooling mode.

[0029] Compared to conventional vapor compression systems that cannot control cooling capacity when operating in natural cooling mode, the control circuitry of vapor compression system 400 is configured to adjust the cooling capacity of vapor compression system 400 (e.g., HVAC&R system) based on ambient temperature conditions when operating in natural cooling mode.

[0030] The vapor compression system 400 circulates refrigerant through a refrigeration circuit 402, which begins with the compressor 404, followed by the condenser 406, bypass 409 and / or expansion valve or device 408, and evaporator 410. The passage to the bypass 409 can be controlled by the bypass valve 409, which can be controlled to open to facilitate full bypass or parallel flow with the expansion valve or device 408, limiting pressure drop and any corresponding temperature drop. Some examples of fluids that can be used as refrigerants in the vapor compression system 400 are hydrofluorocarbon (HFC) based refrigerants, such as R-410A, R-407, R-134a, hydrofluoroolefins (HFO), “natural” refrigerants such as ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon-based refrigerants, water vapor, or any other suitable refrigerant.

[0031] Although the refrigeration circuit 402 is shown as including a compressor 404 (e.g., a single-stage or multi-stage compressor), a condenser 406, an expansion valve or device 408, and an evaporator 410, the scope of this disclosure is not limited to the illustrated embodiments. In some embodiments, without departing from the scope of this disclosure, the refrigeration circuit 402 may include additional or alternative components, refrigerant flow paths, etc., in addition to the compressor 404 and evaporator 410 that form part of the refrigeration circuit 402.

[0032] The vapor compression system 400 may also include a motor 412, a control panel 414, a pump 416 (which is also a differential pressure generator 416), and a three-way valve 418. Although the pump 416 and the three-way valve 418 are shown positioned between the condenser 406 and the expansion device 408, the scope of this disclosure is not limited to the illustrated embodiment. In some embodiments, for example, the pump 416 may be positioned in parallel with the expansion device 408 between the condenser 406 and the evaporator 410. In some embodiments, the pump 416 may be positioned between the expansion device 408 and the evaporator 410. In some embodiments, the pump 416 and the three-way valve 418 may be positioned at other suitable locations in the refrigeration circuit 402 to maintain refrigeration flow between the condenser 406 and the evaporator 410 when the compressor 404 is not operating (e.g., off).

[0033] Control panel 414 may include analog-to-digital converter (ADC) 420, controller 422 (e.g., application-specific integrated circuit (ASIC) processor, reduced instruction set computer (RISC) processor, complex instruction set computer (CISC) processor, field-programmable gate array (FPGA), integrated circuit, microcontroller, microprocessor, digital signal processor), memory 424, and interface board 426. For illustrative purposes, Figure 4 Electrical connections are shown as dashed lines, and fluid flow is indicated by solid arrows.

[0034] In some embodiments, the motor 412 driving the compressor 404 may be a constant speed driver or a variable speed driver (VSD) (e.g., Figure 2 and Figure 3 The VSD (52) in the motor 412 is powered by a VSD. The VSD can receive alternating current (AC) power with a specific fixed line voltage and fixed line frequency from an AC power source and supply power with variable voltage and frequency to the motor 412. In one embodiment, the motor 412 can be powered directly from an AC or direct current (DC) power source. The motor 412 can include any type of motor that can be powered by a VSD, a constant speed drive, 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.

[0035] Compressor 404 may include an inlet 428, an outlet 430, a pre-rotating vane (PRV) 432 disposed at the inlet 428, and a variable geometry diffuser (VGD) 434 disposed at the outlet 430. The PRV 432 and VGD 434 are flow control devices disposed at the inlet 428 and outlet 430 of compressor 404, respectively, to achieve capacity control. For example, the orifice diameter of the PRV 432 can be adjusted within the range of 0% (fully closed position) and 100% (fully open position). Similarly, the orifice diameter of the VGD 434 can be adjusted within the range of 0% (fully closed position) and 100% (fully open position).

[0036] When motor 412 is turned on, compressor 404 is configured to perform compression operation. During compression operation, compressor 404 can receive refrigerant vapor from suction line 436 at inlet 428 and deliver the compressed refrigerant vapor to the inlet of condenser 406 via discharge passage and outlet 430. However, when motor 412 is turned off, compression operation of compressor 404 ceases, and refrigerant vapor received at inlet 428 can pass through compressor 404 without any compression. Figure 5 Further description of the operation of compressor 404.

[0037] Now refer to Figure 5 A diagram illustrating a compressor 404 driven by a motor 412 according to an embodiment of the present disclosure is shown. The compressor 404 may be, for example, a centrifugal compressor. Figure 5 As shown, compressor 404 may include housing 502, rotating shaft 504, and impeller 506. Housing 502 may house rotating shaft 504, impeller 506, and various other components of compressor 404. As shown, housing 502 may also house motor 412. However, in some embodiments, motor 412 may be external to housing 502. Motor 412 is coupled to rotating shaft 504 to drive rotating shaft 504. Motor 412 may include stator and rotor. Stator is the stationary part of the motor's electromagnetic circuit, which applies radial and axial magnetic forces to rotor. Rotor is the rotating part of the motor's electromagnetic circuit, which rotates under the influence of the radial and axial magnetic forces imparted by stator. Rotor is coupled to rotating shaft 504 such that rotating shaft 504 rotates based on the rotation of rotor.

[0038] The rotating shaft 504 and the rotor rotate together about a rotation axis to transmit torque and rotation to other parts and / or components coupled to the motor 412. The rotating shaft 504 is coupled to the impeller 506 at one end. In some embodiments, the rotating shaft 504 may be coupled to the impeller 506 using a direct drive connection. A direct drive connection may include mechanical fasteners (e.g., bolts, pins) for coupling the rotating shaft 504 to the impeller 506. The motor 412 rotates the rotating shaft 504, which in turn rotates the impeller 506. The rotation of the impeller 506 performs a compression operation on the refrigerant vapor received at the inlet 428 of the compressor 404.

[0039] When the motor 412 stops, the rotating shaft 504 stops rotating. Consequently, the impeller 506 connected to the rotating shaft 504 also stops rotating. In this situation, the refrigerant vapor entering the inlet 428 of the compressor 404 flows freely through the impeller 506 without being compressed.

[0040] Return to reference Figure 4 In some embodiments, compressor 404 may be further integrated with one or more pressure sensors for measuring the intake and discharge pressures of compressor 404, one or more temperature sensors for measuring the intake and discharge temperatures of compressor 404, and / or one or more position sensors for measuring the position / state of PRV 432 and VGD 434. Sensing data from the pressure sensors, temperature sensors, and / or position sensors is transmitted to control panel 414 for further processing to maintain operation of the vapor compression system 400 according to this embodiment.

[0041] Refrigerant vapor delivered by compressor 404 to condenser 406 transfers heat to a cooling fluid, such as water or air. Due to heat transfer with the cooling fluid, the refrigerant vapor condenses into liquid refrigerant in condenser 406. The liquid refrigerant from condenser 406 flows through expansion device 408 (e.g., expansion valve) to evaporator 410. In some embodiments, condenser 406 may include a temperature sensor S1 disposed at the inlet of condenser 406 from which cooling fluid enters condenser 406. Temperature sensor S1 may be configured to measure (or sense, detect) the temperature of the cooling fluid entering condenser 406 and generate sensing data. Temperature sensor S1 may then transmit the sensed data to control panel 414 for further processing.

[0042] The liquid refrigerant supplied to evaporator 410 absorbs heat from another fluid, which may or may not be the same type of fluid used in condenser 406, and undergoes a phase change to refrigerant vapor. Figure 4In the exemplary embodiment shown, the evaporator 410 includes an exchanger coil 438 having a supply line 440S and a return line 440R connected to the load 442 to be cooled. A conditioning fluid, such as ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable liquid, enters the evaporator 410 via the return line 440R and exits the evaporator 410 via the supply line 442S. The evaporator 410 cools the conditioning fluid in the exchanger coil 438. Vaporized refrigerant exits the evaporator 410 and returns to the compressor 404 via the suction line 436 to complete the cycle.

[0043] In some embodiments, the evaporator 410 may include a temperature sensor S2 disposed at the inlet of the evaporator 410, at which regulating fluid enters the evaporator 410. The temperature sensor S2 may be configured to measure (or sense, detect) the temperature of the regulating fluid entering the evaporator 410 and generate sensing data. The temperature sensor S2 may then transmit the sensed data to a control panel 414 for further processing.

[0044] Liquid refrigerant leaving condenser 406 can be delivered to evaporator 410 via either first path 444 or second path 446. A three-way valve 418, controlled by controller 422, can selectively circulate the liquid refrigerant leaving condenser 406 via either first path 444 or second path 446. When motor 412 is on and compressor 404 is performing compression operation, three-way valve 418 can be configured to close second path 446 and open first path 444, allowing liquid refrigerant leaving condenser 406 to circulate via first path 444. In first path 444, liquid refrigerant leaving condenser 406 is transferred to evaporator 410 by bypassing pump 416. However, when motor 412 is off (or stopped) and compression operation of compressor 404 ceases, three-way valve 418 can be configured to close first path 444 and open second path 446. Liquid refrigerant leaving condenser 406 then circulates via second path 446. In the second path 446, liquid refrigerant exiting condenser 406 is transferred to evaporator 410 via pump 416. Pump 416, when activated by controller 422, is configured to pressurize the refrigerant even when compressor 404 is off to maintain refrigerant flow and circulate the refrigerant through refrigeration circuit 402. In other words, liquid refrigerant exiting condenser 406 can bypass pump 416 when compressor 404 is on (“on”) and can flow through pump 416 when compressor 404 is off (“off” or “stopped”). It should be noted that in some embodiments, pump 416 can be replaced by a differential pressure generator, which, without departing from the scope of this disclosure, includes any suitable means or configuration that operates to pressurize the refrigerant to maintain refrigerant circulation when compressor 404 is stopped.

[0045] Control panel 414 may include ADC 420 to receive analog input signals from various components of vapor compression system 400. Such analog input signals can indicate the performance of vapor compression system 400. For example, input signals received by control panel 414 may include the temperature of the fluid entering condenser 406 and evaporator 410, refrigerant pressure in evaporator 410 and condenser 406, etc. ADC 420 may be configured to convert the received analog signals into digital input signals and provide the converted input signals to controller 422 for further processing.

[0046] Control panel 414 may include memory 424 to store various control algorithms executable by controller 422. The control algorithm may be a computer program stored in memory 424 and has a series of instructions executable by controller 422. The one or more control algorithms may be executable to control the operation of vapor compression system 400. For example, control panel 414 may use control algorithms to selectively operate vapor compression system 400 in a conventional cooling mode or a natural cooling mode based on the temperature of the cooling fluid entering condenser 406. In natural cooling mode, control panel 414 may further use multiple control algorithms to adjust the position of at least one of PRV 432 and VGD 434 to control the cooling capacity of vapor compression system 400.

[0047] Although the control algorithm can be embodied in a computer program and executed by the controller 422 (e.g., a control circuit system), those skilled in the art will understand that the control algorithm can be implemented and executed using digital and / or analog hardware. If hardware is used to execute the control algorithm, the corresponding configuration of the control panel 414 can be changed to incorporate necessary components and remove any components that may no longer be needed.

[0048] Control panel 414 may include controller 422 to execute or use a single or central control algorithm or control system to control vapor compression system 400 and its components. In one embodiment, the control system may be a computer program or software having a series of instructions executable by controller 422. In another embodiment, the control system may be implemented and executed by someone skilled in the art using digital and / or analog hardware. In yet another embodiment, control panel 414 may incorporate multiple controllers, each performing a discrete function, wherein a central controller determines the output of control panel 414. If hardware is used to execute the control algorithm, the corresponding configuration of control panel 414 can be modified to incorporate necessary components and remove any components that may no longer be needed.

[0049] The central control algorithm executed by controller 422 may include a mode control program or algorithm to selectively operate the vapor compression system 400 (HVAC&R system) in either a conventional cooling mode or a natural cooling mode. When executed, the mode control program can cause controller 422 to automatically select either a conventional cooling mode or a natural cooling mode to operate the vapor compression system 400. Controller 422 can provide appropriate control signals to control motor 412, pump 416, and three-way valve 418, based on the selection of either the conventional cooling mode or the natural cooling mode.

[0050] The central control algorithm executed by controller 422 may also include a capacity control program or algorithm to control the cooling capacity of vapor compression system 400 in natural cooling mode. When executed, the capacity control program may cause controller 422 to provide control signals via interface board 426 to the actuators of PRV 432 and / or VGD 434 to adjust the position of PRV 432 and / or VGD 434. Controller 422 may also be configured to use feedback (e.g., continuous feedback) from temperature sensor S1 to monitor temperature changes in the cooling fluid.

[0051] Control panel 414 may also include interface board 426 to transmit actuation and control signals generated by controller 422 to various components of vapor compression system 400 to control the operation of vapor compression system 400. For example, control panel 414 may be configured to transmit actuation signals to stop motor 412 and activate pump 416 when natural cooling mode is selected. Control panel 414 may also be configured to transmit actuation and control signals to control the position of PRV 432 and / or VGD 434 for capacity control during natural cooling mode.

[0052] In one embodiment, control panel 414 may be connected to or configured to be integrated with user interface 448, which allows an operator to interact with control panel 414. The operator can select and enter commands for control panel 414 through user interface 448. Furthermore, user interface 448 can display messages and information from control panel 414 regarding the operating status of vapor compression system 400 to the operator. User interface 448 may be located locally on control panel 414, for example, mounted on vapor compression system 400 or control panel 414, or alternatively, user interface 448 may be located remotely from control panel 414, for example, in a separate control room separate from vapor compression system 400. (To be continued...) Figure 6A and Figure 6B Describe the operation of the vapor compression system 400 in both conventional cooling mode and natural cooling mode.

[0053] Although the vapor compression system 400 is shown as including a pump 416 and a three-way valve 418, the scope of this disclosure is not limited to the illustrated embodiment. In some embodiments, the vapor compression system 400 may not include the pump 416 and the three-way valve 418. In such a vapor compression system, the flow of liquid refrigerant between the condenser 406 and the evaporator 410 can be maintained due to the pressure difference between the condenser 406 and the evaporator 410, even when the compressor 404 is off (e.g., in an off state). The pressure difference between the condenser 406 and the evaporator 410 may be due to the height difference between the condenser 406 and the evaporator 410. Therefore, when the compressor 404 stops, the refrigerant can naturally flow from the condenser 406 to the evaporator 410, thereby maintaining the flow of refrigerant in the refrigeration circuit 402. This configuration may be an example of a pressure differential generator. Similar to the vapor compression system 400, vapor compression systems that include a pressure differential generator that is not a pump (e.g., pump 416) may also operate in a conventional cooling mode or a natural cooling mode based on ambient temperature conditions.

[0054] Figure 6A This is a block diagram of a vapor compression system 400 (e.g., an HVAC&R system) operating in a conventional cooling mode according to some embodiments of this disclosure. The ADC 420 can be configured to receive sensing data (e.g., an analog input signal) from a temperature sensor S1. The sensed data can indicate (e.g., directly or indirectly) the temperature of the cooling fluid entering the inlet of the condenser 406 via the return line 602R. The ADC 420 can convert the received sensing data into a format compatible with the controller 422 and provide the converted sensing data to the controller 422. Although in Figure 6A In this embodiment, controller 422 is shown receiving sensing data from temperature sensor S1 via ADC 420; however, this disclosure is not limited to this embodiment. In some embodiments, controller 422 may receive sensing data directly from temperature sensor S1 or from a different sensor that provides the relevant data.

[0055] When cooling operation is required, controller 422 may execute a mode control program or algorithm to selectively operate the vapor compression system 400 in a conventional cooling mode or a natural cooling mode. Controller 422 may determine whether cooling operation is desired based on, for example, the temperature setting of the thermostat, the temperature of the return air, the temperature of the supply air, and the temperature of the regulating fluid entering or leaving the evaporator 410. In an example, when the temperature of the return air is substantially the same as or lower than the temperature of the supply air, controller 422 may determine that cooling operation is not desired. However, when the temperature of the return air is higher than the temperature of the supply air, controller 422 may determine that cooling operation is desired. In some embodiments, without departing from the scope of this disclosure, controller 422 may utilize some other control logic known in the art to determine whether cooling operation is desired (e.g., required).

[0056] When determining the desired cooling operation, controller 422 can execute a mode control program or algorithm to selectively operate vapor compression system 400 in either a conventional cooling mode or a natural cooling mode. Controller 422 can compare the temperature of the cooling fluid entering condenser 406 with a first threshold temperature value and generate a first comparison result. When the first comparison result indicates that the temperature of the cooling fluid is greater than the first threshold temperature value, controller 422 can select the conventional cooling mode to operate vapor compression system 400. In response to the selection of the conventional cooling mode, controller 422 can be configured to generate control signals to operate motor 412, pump 416, and three-way valve 418 according to the conventional cooling mode. Controller 422 can provide control signals to motor 412, pump 416, and three-way valve 418, for example, via interface board 426 or direct communication.

[0057] When a control signal is received by three-way valve 418, it can open the first path 444 for refrigerant flow and close the second path 446. Based on the control signal, three-way valve 418 opens the first path 444 (indicated by the solid line) and closes the second path 446 (indicated by the dashed line). This configuration allows liquid refrigerant leaving condenser 406 to be delivered to evaporator 410 via the first path 444 without passing through pump 416. Furthermore, in normal cooling mode, based on a control signal provided by controller 422, motor 412 is turned on (e.g., in the on state) and pump 416 remains off (e.g., in the off state).

[0058] When the control signal is received by the motor 412, the motor 412 can be started, and the motor 412 can drive the rotating shaft 504 (e.g., Figure 5(As shown). Rotating shaft 504 transmits torque to drive impeller 506, which results in compression of the refrigerant vapor received from evaporator 410 at inlet 428 of compressor 404. Controller 422 can be configured to operate vapor compression system 400 in a normal cooling mode until the temperature of the cooling fluid entering condenser 406 becomes equal to or below a first threshold temperature value. The first threshold temperature value can be preset by the operator, installer, manufacturer, etc., of vapor compression system 400 using user interface 448 or other technologies. In some embodiments, the first threshold temperature value can be set automatically by controller 422 or manually by the operator based on cooling temperature requirements. The first threshold temperature value can be stored in memory 424.

[0059] Figure 6B This is a block diagram of a vapor compression system 400 (e.g., an HVAC&R system) operating in natural cooling mode according to embodiments of the present disclosure. When cooling operation is required and a first comparison result (e.g., generated by comparing the temperature of the cooling fluid entering the condenser 406 with a first threshold temperature value) indicates that the temperature of the cooling fluid is at a specific level (e.g., within a range), such as less than or equal to the first threshold temperature value, the controller 422 can initiate or maintain operation in natural cooling mode. For example, the controller 422 can utilize temperature data to determine whether the cooling capacity in natural cooling mode is sufficient to meet the cooling demand. If the controller 422 determines that the cooling capacity in natural cooling mode is insufficient to meet the cooling demand, the controller 422 can select a conventional cooling mode to operate the vapor compression system 400, such as... Figure 6A As shown. However, if the controller 422 determines that the cooling capacity in natural cooling mode is sufficient to meet the cooling demand, the controller 422 may select natural cooling mode to operate the vapor compression system 400. The controller 422 may determine the cooling demand based on, for example, the temperature setting of the thermostat, the temperature of the return air, the temperature of the supply air, and the temperature of the regulating fluid entering or leaving the evaporator 410. In one embodiment, according to this disclosure, the controller 422 may utilize some other control logic known in the art to determine the cooling demand.

[0060] When the natural cooling mode is selected, the controller 422 can be configured to execute a capacity control program to control the cooling capacity of the vapor compression system 400 operating in natural cooling mode. The controller 422 can be configured to control the cooling capacity of the vapor compression system 400 operating in natural cooling mode based on cooling demand. While executing the capacity control program in natural cooling mode, the controller 422 can be configured to compare the current cooling capacity of the vapor compression system 400 with the cooling demand and generate a second comparison result. The second comparison result can indicate the difference between the current cooling capacity of the vapor compression system 400 and the cooling demand. The controller 422 can then determine the new cooling capacity required to meet the cooling demand.

[0061] Controller 422 can be configured to generate control signals to operate motor 412, pump 416, and three-way valve 418 according to a natural cooling mode. Controller 422 can be configured to generate actuation signals to adjust PRV 432 and / or VGD 434, thereby controlling the cooling capacity of the vapor compression system 400 operating in natural cooling mode, for example, to meet cooling requirements. Controller 422 can provide control signals to motor 412, pump 416, and three-way valve 418, and actuation signals to PRV 432 and / or VGD 434, for example, via interface board 426 or direct communication.

[0062] When a control signal is received by the three-way valve 418, it can close the first path 444 and open the second path 446 for refrigerant flow. Based on the control signal, the three-way valve 418 opens the second path 446 (indicated by the solid line) and closes the first path 444 (indicated by the dashed line). The opening of the second path 446 allows liquid refrigerant leaving the condenser 406 to be delivered to the evaporator 410 via the second path 446. While flowing through the second path 446, the liquid refrigerant flows through the pump 416.

[0063] When a control signal is received by pump 416, it activates pump 416 (e.g., enters an on state). The activated pump 416 pressurizes the liquid refrigerant to supply liquid refrigerant to evaporator 410 (causing liquid refrigerant flow). When a control signal is received by motor 412, it stops motor 412 (e.g., enters a off state). As a result, rotating shaft 504 (e.g.) Figure 5 As shown, the impeller 506 also stops rotating, causing the compression operation at compressor 404 to cease. Therefore, the refrigerant pressurized by the activated pump 416 circulates through the refrigeration circuit 402 and flows freely through impeller 506. In some embodiments, pump 416 may refer to a pressure differential generator that is not a pump.

[0064] In some embodiments, controller 422 may provide an actuation signal to one or more actuators of PRV 432 to adjust PRV 432 to a position that meets cooling requirements. In an example, controller 422 may be configured to receive sensor readings from a position sensor that monitors the position of PRV 432. When the current position of PRV 432 results in a cooling capacity greater than the desired (or determined) cooling capacity, the actuation signal provided by controller 422 may adjust the current position of PRV 432 to reduce the cooling capacity. The current position of PRV 432 may be a fully open position or a partially closed position. The actuation signal may cause the actuator to gradually drive PRV 432 from its current position toward a fully closed position. Based on the actuation signal, the actuator may gradually or incrementally close PRV 432 until the cooling requirement is met or the fully closed position is reached. As PRV 432 gradually closes, controller 422 may continue to monitor the temperature of the regulating fluid leaving evaporator 410 to detect changes in the cooling capacity of vapor compression system 400. When the cooling capacity of the vapor compression system 400 matches the cooling demand, the controller 422 can stop the actuation signal and maintain the PRV 432 at a position that meets the cooling demand. In another example, the current position of the PRV 432 may result in a cooling capacity that is less than the expected (or determined) cooling capacity. In this case, the actuation signal provided by the controller 422 can adjust the current position of the PRV 432 to increase the cooling capacity. The current position of the PRV 432 can be a partially closed position. The actuation signal can cause the actuator to gradually drive the PRV 432 from its current position toward a fully open position. Based on the actuation signal, the actuator can gradually or incrementally open the PRV 432 until the cooling demand is met or the fully open position is reached. As the PRV 432 gradually opens, the controller 422 can continue to monitor the temperature of the regulating fluid leaving the evaporator 410 to detect changes in the cooling capacity of the vapor compression system 400. When the cooling capacity of the vapor compression system 400 matches the cooling demand, the controller 422 can stop the actuation signal and maintain the PRV 432 at a position that meets the cooling demand.

[0065] In some embodiments, controller 422 may provide an actuation signal to one or more actuators of VGD 434 to adjust VGD 434 to a position that meets cooling requirements. In an example, controller 422 may be configured to receive sensor readings from a position sensor that monitors the position of VGD 434. When the current position of VGD 434 results in a cooling capacity greater than the desired (or determined) cooling capacity, the actuation signal provided by controller 422 may adjust the current position of VGD 434 to reduce the cooling capacity. The current position of VGD 434 may be a fully open position or a partially closed position. The actuation signal may cause the actuator to gradually drive VGD 434 from its current position toward a fully closed position. Based on the actuation signal, the actuator may gradually or incrementally close VGD 434 until the cooling requirement is met or the fully closed position is reached. As VGD 434 gradually closes, controller 422 may continue to monitor the temperature of the regulating fluid leaving evaporator 410 to detect changes in the cooling capacity of vapor compression system 400. When the cooling capacity of the vapor compression system 400 matches the cooling demand, the controller 422 can stop the actuation signal and maintain VGD 434 at a position that meets the cooling demand. In another example, the current position of VGD 434 may result in a cooling capacity less than the desired (or determined) cooling capacity. In this case, the actuation signal provided by the controller 422 can adjust the current position of VGD 434 to increase the cooling capacity. The current position of VGD 434 may be a partially closed position. The actuation signal can cause the actuator to gradually drive VGD 434 from its current position toward a fully open position. Based on the actuation signal, the actuator can gradually or incrementally open VGD 434 until the cooling demand is met or the fully open position is reached. As VGD 434 gradually opens, the controller 422 can continue to monitor the temperature of the regulating fluid leaving the evaporator 410 to detect changes in the cooling capacity of the vapor compression system 400. When the cooling capacity of the vapor compression system 400 matches the cooling demand, the controller 422 can stop the actuation signal and maintain VGD 434 at the position that meets the cooling demand.

[0066] According to embodiments of this disclosure, controller 422 can provide actuation signals to the actuators of PRV 432 and VGD 434 to adjust PRV 432 and VGD 434 in combination to meet cooling requirements. Controller 422 can additionally or alternatively adjust the opening of expansion device 408, for example, from a fully open position to a partially closed position, to control the cooling capacity of vapor compression system 400. Bypass valve 409 can be controlled similarly or separately. In some embodiments, expansion device 408 can be completely bypassed, or parallel flow can be established via bypass 409 and bypass valve 411 to limit pressure drop and corresponding temperature drop. Furthermore, VSD can be used to control pump 416. In such cases, the cooling capacity of vapor compression system 400 can be controlled additionally or alternatively by controlling the pumping power of pump 416. For example, the pumping power can be reduced by controller 422 to reduce cooling capacity, and the pumping power can be increased to increase cooling capacity. Different differential pressure generators can be controlled differently.

[0067] The volume-controlled refrigerant vapor flowing from compressor 404 to condenser 406 transfers heat to the cooling fluid entering condenser 406. Due to heat transfer with the cooling fluid, the refrigerant vapor condenses into refrigerant liquid in condenser 406. The liquid refrigerant from condenser 406 flows to evaporator 410 via a second path 446, for example, via pump 416, and then via a fully or partially open expansion device 408 (e.g., an expansion valve). In some embodiments, the second path 446 may bypass or extend parallel to expansion device 408. The liquid refrigerant delivered to evaporator 410 absorbs heat from the conditioning fluid entering evaporator 410 and may undergo a phase change to refrigerant vapor. As a result, the conditioning fluid in exchanger coil 438 is cooled to meet cooling requirements. The vaporized refrigerant leaves evaporator 410 and returns to compressor 404 to complete the cycle.

[0068] When the vapor compression system 400 operates in natural cooling mode, the controller 422 can monitor the cooling capacity periodically, continuously, or at slightly random time intervals. If the current cooling capacity deviates from the cooling demand, the controller 422 can execute the aforementioned capacity control procedure to adjust at least one of PRV 432 and VGD 434. Furthermore, if the cooling capacity in natural cooling mode is insufficient to meet the cooling demand, the controller 422 can switch from natural cooling mode to conventional cooling mode.

[0069] When the vapor compression system 400 operates in natural cooling mode, the controller 422 can further monitor the temperature of the cooling fluid entering the condenser 406 to determine whether natural cooling mode can continue. In an exemplary scenario, when the vapor compression system 400 operates in natural cooling mode, the temperature of the cooling fluid entering the condenser 406 may exceed a first threshold temperature value. In this case, the controller 422 can switch from natural cooling mode to conventional cooling mode.

[0070] When the temperature of the cooling fluid entering the condenser 406 becomes less than or equal to a first threshold temperature and the cooling capacity in natural cooling mode becomes sufficient to meet the cooling demand, the controller 422 can switch back from the conventional cooling mode to the natural cooling mode. In other words, when cooling operation is required, the controller 422 can control the vapor compression system 400 to operate in either conventional cooling mode or natural cooling mode based on the operating conditions of the vapor compression system 400 (e.g., the temperature of the cooling fluid entering the condenser 406, cooling demand).

[0071] In another example scenario, when the vapor compression system 400 is operating in natural cooling mode, the controller 422 can determine that cooling operation is no longer required. In this case, the controller 422 can be configured to stop the circulation of refrigerant in the refrigeration circuit 402. To stop the refrigerant circulation, the controller 422 can be configured to generate a control signal that, when received by the pump 416, causes the pump 416 to stop. When the compressor 404 has already been deactivated, deactivating the pump 416 stops the circulation of refrigerant in the refrigeration circuit 402.

[0072] In some embodiments, during normal cooling mode or natural cooling mode, controller 422 may be configured to determine the likelihood of conditioning fluid freezing in one or more pipes of evaporator 410 (e.g., exchanger coil 438, supply line 440S, and return line 440R). In one example, the circulation of conditioning fluid through evaporator 410 may stop due to a fault or error, and some conditioning fluid may remain in the pipes of evaporator 410. In this case, controller 422 may determine that the refrigerant flowing through evaporator 410 is likely to cause the conditioning fluid to freeze due to heat exchange between the refrigerant and the conditioning fluid. In response to determining the likelihood of conditioning fluid freezing in evaporator 410, controller 422 may be configured to adjust at least one of PRV 432 and VGD 434 to a fully closed position. Alternatively, controller 422 may be configured to adjust the opening of expansion device 408 (and / or bypass valve 411) to a fully closed position to prevent refrigerant from flowing into evaporator 410. Controller 422 may further temporarily activate pump 416 to draw refrigerant from evaporator 410. With at least one of PRV 432 and VGD 434 (and / or expansion device 408 and bypass valve 409) fully closed, refrigerant may not flow into evaporator 410. In the absence of available refrigerant in evaporator 410, controller 422 prevents the regulating fluid in evaporator 410 from freezing. When the likelihood of refrigerant flow through evaporator 410 causing the regulating fluid to freeze is no or very low, controller 422 may open the closed PRV 432, VGD 434, expansion device 408, and / or bypass valve 411. In some embodiments, expansion device 408 may be closed, and bypass valve 411 may be fully open to facilitate desired flow.

[0073] although Figure 4 , Figure 6A and Figure 6B The use of HVAC&R systems (e.g., vapor compression system 400) to cool spaces is described, but the scope of this disclosure is not limited to these embodiments. In practice, HVAC&R systems (e.g., vapor compression system 400) can also be used to heat environments. Figure 7A and 7B The steam compression system is described as working as a boiler to heat a space.

[0074] Figure 7A and Figure 7B This is a block diagram of a vapor compression system 700 that can be used for heating in an HVAC&R system 10 according to an embodiment of the present disclosure. Figure 1 Boiler 16 can be used Figure 7A and 7BThis is achieved through the vapor compression system 700 shown. Except for its use in heating the space, the vapor compression system 700 is similar to the vapor compression system 400. In one embodiment, the vapor compression system 700 represents a reconfiguration of the vapor compression system 400, similar to a heat pump, where the heat exchanger switches between operating as a condenser 406 and an evaporator 410. This is achieved through... Figure 6A and 6B The load 442 that exchanges heat with the evaporator 410 is shown in the diagram. Figure 7A and 7B The switching is illustrated by showing the load 706 that exchanges heat with the condenser 406.

[0075] The refrigerant vapor delivered from compressor 404 to condenser 406 transfers heat to the conditioning fluid (e.g., ethylene glycol, calcium chloride brine, sodium chloride brine), and condenses into refrigerant liquid in condenser 406 due to heat transfer with the conditioning fluid. Figure 7A and 7B In the exemplary embodiment shown, the condenser 406 includes an exchanger coil 702 having a supply line 704S and a return line 704R connected to the load 706 to be heated. Conditioning fluid enters the condenser 406 via the return line 704R and exits the condenser 406 via the supply line 704S. The condenser 406 heats the conditioning fluid in the exchanger coil 702. The refrigerant liquid then exits the condenser 406 and is transferred to the expansion device 408.

[0076] Figure 7A and Figure 7B The other components of the 700 steam compression system operate similarly to those in... Figure 4 and Figure 5 The operation of the corresponding components of the vapor compression system 400 described above. However, the vapor compression system 700 can be operated to switch between a conventional heating mode and a natural heating mode based on ambient temperature conditions. The vapor compression system 700 may include a control circuit system configured to selectively operate the vapor compression system 700 in a conventional heating mode or a natural heating mode, including switching between the conventional heating mode and the natural heating mode. Furthermore, the control circuit system of the vapor compression system 700 is configured to adjust the heating capacity of the vapor compression system 700 according to ambient temperature conditions when the vapor compression system 700 operates in natural heating mode. Figure 7A The operation of the vapor compression system 700 in conventional heating mode is described, and combined with Figure 7B The operation of the vapor compression system 700 in natural heating mode is described.

[0077] Although the refrigeration circuit 402 is shown as including a compressor 404, a condenser 406, an expansion valve or expansion device 408, and an evaporator 410, the scope of this disclosure is not limited to the illustrated embodiment. In some embodiments, without departing from the scope of this disclosure, the refrigeration circuit 402 may include additional or alternative components, refrigerant flow paths, etc., in addition to the compressor 404 and condenser 406. For example, in the illustrated embodiment, a bypass 409 is included to facilitate refrigerant flow in certain situations.

[0078] refer to Figure 7A The ADC 420 can be configured to receive sensing data from the temperature sensor S2. The sensing data may indicate (e.g., directly or indirectly) the temperature of the heating fluid entering the inlet of the evaporator 410 via the return line 440R. The ADC 420 can convert the received sensing data into a format compatible with the controller 422 and provide the converted sensing data to the controller 422. Figure 7A The illustration shows that controller 422 receives sensing data from temperature sensor S2 via ADC 420. However, in other embodiments, controller 422 may receive sensing data directly from temperature sensor S2, from other sensors, etc.

[0079] When heating operation is desired (e.g., required), controller 422 may execute a mode control program or algorithm to selectively operate the vapor compression system 700 in a conventional heating mode or a natural heating mode. Controller 422 may determine whether heating operation is desired based on, for example, the temperature setting of the thermostat, the temperature of the return air, the temperature of the supply air, the temperature of the regulating fluid entering or leaving the condenser 406, etc. For example, when the temperature of the return air is substantially the same as or higher than the temperature of the supply air, controller 422 may determine that heating operation is not desired. However, when the temperature of the return air is lower than the temperature of the supply air, controller 422 may determine that heating operation is required. In some embodiments, without departing from the scope of this disclosure, controller 422 may utilize some other control logic known in the art to determine whether heating operation is desired (e.g., required).

[0080] When determining the desired heating operation, controller 422 can execute a mode control program or algorithm to selectively operate vapor compression system 700 in either a conventional heating mode or a natural heating mode. Controller 422 can compare the temperature of the heating fluid entering evaporator 410 with a second threshold temperature value and generate a third comparison result. When the third comparison result indicates that the temperature of the heating fluid is below the second threshold temperature value, controller 422 can select the conventional heating mode to operate vapor compression system 700. In response to the selection of the conventional heating mode, controller 422 can be configured to generate control signals to operate motor 412, pump 416, and three-way valve 418 according to the conventional heating mode. Controller 422 can provide control signals to motor 412, pump 416, and three-way valve 418, for example, via interface board 426 or direct communication.

[0081] When a control signal is received by three-way valve 418, it can cause three-way valve 418 to open the first path 444 for refrigerant flow and close the second path 446. Based on the control signal, three-way valve 418 opens the first path 444 (indicated by the solid line) and closes the second path 446 (indicated by the dashed line). This configuration allows liquid refrigerant leaving condenser 406 to bypass pump 416 and be delivered to evaporator 410 via the first path 444. Furthermore, in normal heating mode, based on a control signal provided by controller 422, motor 412 is turned on (e.g., in the on state), and pump 416 remains off (e.g., in the off state).

[0082] When the control signal is received by the motor 412, the motor 412 can be started, and the motor 412 can drive the rotating shaft 504 (e.g., Figure 5 (As shown). Rotating shaft 504 transmits torque to drive impeller 506, which results in compression of the refrigerant vapor received from evaporator 410 at inlet 428 of compressor 404. Controller 422 can be configured to operate vapor compression system 700 in a normal heating mode until the temperature of the heating fluid entering evaporator 410 becomes equal to or greater than a second threshold temperature value. The second threshold temperature value can be preset using user interface 448 or another technique. In some embodiments, the second threshold temperature value can be set automatically by controller 422 or manually by an operator based on heating temperature requirements. The second threshold temperature value can be stored in memory 424.

[0083] refer to Figure 7BWhen heating operation is required and a third comparison result (e.g., generated by comparing the temperature of the heating fluid entering evaporator 410 with a second threshold temperature value) indicates that the temperature of the heating fluid is at a specific level (e.g., within a range), such as greater than or equal to the second threshold temperature value, controller 422 can initiate or maintain operation in natural cooling mode. For example, controller 422 can utilize temperature data to determine whether the heating capacity in natural heating mode is sufficient to meet the heating demand. Controller 422 can determine the heating demand based on, for example, the temperature setting of the thermostat, the temperature of the return air, the temperature of the supply air, the temperature of the regulating fluid entering condenser 406 after the regulating space, etc. In some other embodiments, controller 422 can utilize some other control logic known in the art to determine the heating demand without departing from the scope of this disclosure. If controller 422 determines that the heating capacity in natural heating mode is insufficient to meet the heating demand, controller 422 can select a conventional heating mode to operate vapor compression system 700, such as... Figure 7A As shown. However, if the controller 422 determines that the heating capacity in the natural heating mode is sufficient to meet the heating demand, the controller 422 may select the natural heating mode to operate the vapor compression system 700.

[0084] When the natural heating mode is selected, the controller 422 can be configured to execute a capacity control program to control the heating capacity of the vapor compression system 700 operating in natural heating mode. The controller 422 can be configured to control the heating capacity of the vapor compression system 700 operating in natural heating mode based on heating demand. While executing the capacity control program in natural heating mode, the controller 422 can be configured to compare the current heating capacity of the vapor compression system 700 with the heating demand and generate a fourth comparison result. The fourth comparison result can indicate the difference between the current heating capacity of the vapor compression system 700 and the heating demand. The controller 422 can then determine the new heating capacity required to meet the heating demand.

[0085] Controller 422 can be configured to generate control signals to operate motor 412, pump 416, and three-way valve 418 according to a natural heating mode. Controller 422 can be configured to generate actuation signals to adjust PRV 432 and / or VGD 434, thereby controlling the heating capacity of the vapor compression system 700 operating in natural heating mode, for example, to meet heating demands. Controller 422 can provide control signals to motor 412, pump 416, and three-way valve 418, and actuation signals to PRV 432 and / or VGD 434, for example, via interface board 426 or direct communication.

[0086] When a control signal is received by three-way valve 418, it can close the first path 444 and open the second path 446 for refrigerant flow. Based on the control signal, three-way valve 418 opens the second path 446 (indicated by the solid line) and closes the first path 444 (indicated by the dashed line). The opening of the second path 446 allows liquid refrigerant leaving condenser 406 to be delivered to evaporator 410 via the second path 446. While flowing through the second path 446, the liquid refrigerant flows through pump 416. When a control signal is received by pump 416, it activates pump 416. The activated pump 416 pressurizes the liquid refrigerant to supply it to evaporator 410. Pump 416 can represent any type of differential pressure generator.

[0087] When the control signal is received by motor 412, it stops motor 412. As a result, the rotating shaft 504 ( Figure 5 As shown in the diagram, impeller 506 also stops rotating, which causes compression operation at compressor 404 to cease (e.g., enter or remain closed). Therefore, the vaporized refrigerant leaving evaporator 410 flows freely through impeller 506, and pump 416 (or some other differential pressure generator) handles the cycle.

[0088] In some embodiments, controller 422 may provide an actuation signal to one or more actuators of PRV 432 to adjust PRV 432 to a position that meets heating requirements. In an example, controller 422 may be configured to receive sensor readings from a position sensor that monitors the position of PRV 432. When the current position of PRV 432 results in a heating capacity greater than the desired (or determined) heating capacity, the actuation signal provided by controller 422 may adjust the current position of PRV 432 to reduce the heating capacity. The current position of PRV 432 may be a fully open position or a partially closed position. The actuation signal may cause the actuator to gradually drive PRV 432 from its current position toward a fully closed position. Based on the actuation signal, the actuator may gradually or incrementally close PRV 432 until the heating requirement is met or the fully closed position is reached. As PRV 432 gradually closes, controller 422 may continue to monitor the temperature of the regulating fluid leaving condenser 406 to detect changes in the heating capacity of vapor compression system 700. When the heating capacity of the vapor compression system 700 matches the heating demand, the controller 422 can stop the actuation signal and maintain the PRV 432 at a position that meets the heating demand. In another example, the current position of the PRV 432 may result in a heating capacity less than the desired (or determined) heating capacity. In this case, the actuation signal provided by the controller 422 can adjust the current position of the PRV 432 to increase the heating capacity. The current position of the PRV 432 may be a partially closed position. The actuation signal can cause the actuator to gradually drive the PRV 432 from its current position toward a fully open position. Based on the actuation signal, the actuator can gradually or incrementally open the PRV 432 until the heating demand is met or the fully open position is reached. As the PRV 432 gradually opens, the controller 422 can continue to monitor the temperature of the regulating fluid leaving the condenser 406 to detect changes in the heating capacity of the vapor compression system 700. When the heating capacity of the vapor compression system 700 matches the heating demand, the controller 422 can stop the actuation signal and maintain the PRV 432 at the position that meets the heating demand.

[0089] In some embodiments, controller 422 may provide an actuation signal to one or more actuators of VGD 434 to adjust VGD 434 to a position that meets heating requirements. In an example, controller 422 may be configured to receive sensor readings from a position sensor that monitors the position of VGD 434. When the current position of VGD 434 results in a heating capacity greater than the desired (or determined) heating capacity, the actuation signal provided by controller 422 may adjust the current position of VGD 434 to reduce the heating capacity. The current position of VGD 434 may be a fully open position or a partially closed position. The actuation signal may cause the actuator to gradually drive VGD 434 from its current position toward a fully closed position. Based on the actuation signal, the actuator may gradually or incrementally close VGD 434 until the heating requirement is met or the fully closed position is reached. As VGD 434 gradually closes, controller 422 may continue to monitor the temperature of the regulating fluid leaving condenser 406 to detect changes in the heating capacity of vapor compression system 700. When the heating capacity of the vapor compression system 700 matches the heating demand, the controller 422 can stop the actuation signal and maintain VGD 434 at a position that meets the heating demand. In another example, the current position of VGD 434 may result in a heating capacity less than the desired (or determined) heating capacity. In this case, the actuation signal provided by the controller 422 can adjust the current position of VGD 434 to increase the heating capacity. The current position of VGD 434 may be a partially closed position. The actuation signal can cause the actuator to gradually drive VGD 434 from its current position toward a fully open position. Based on the actuation signal, the actuator can gradually or incrementally open VGD 434 until the heating demand is met or the fully open position is reached. As VGD 434 gradually opens, the controller 422 can continue to monitor the temperature of the regulating fluid leaving the condenser 406 to detect changes in the heating capacity of the vapor compression system 700. When the heating capacity of the vapor compression system 700 matches the heating demand, the controller 422 can stop the actuation signal and maintain VGD 434 at the position that meets the heating demand.

[0090] In some embodiments, controller 422 may provide actuation signals to the actuators of PRV 432 and VGD 434 to adjust PRV 432 and VGD 434 in combination to meet heating requirements. In some embodiments, controller 422 may additionally or alternatively adjust the opening of expansion device 408 (and / or bypass valve 411) to control the heating capacity of vapor compression system 700.

[0091] In some embodiments, a VSD can be used to control pump 416. In such cases, the heating capacity of the vapor compression system 700 can be controlled, either additionally or alternatively, by controlling the pumping power of pump 416. For example, the pumping power can be reduced by controller 422 to reduce the heating capacity, and the pumping power can be increased to increase the heating capacity.

[0092] The capacity-controlled refrigerant vapor flowing from compressor 404 to condenser 406 transfers heat to the conditioning fluid entering condenser 406. Due to heat transfer with the conditioning fluid entering condenser 406, the refrigerant vapor condenses into refrigerant liquid in condenser 406. As a result, the conditioning fluid in exchanger coil 702 is heated to meet heating requirements. The liquid refrigerant from condenser 406 flows to evaporator 410 via a second path 446, for example, by pump 416, and then through expansion device 408 (e.g., expansion valve) and / or bypass 409. The liquid refrigerant delivered to evaporator 410 absorbs heat from the heating fluid entering evaporator 410 and may undergo a phase change to refrigerant vapor. The vaporized refrigerant leaves evaporator 410 and returns to compressor 404 to complete the cycle.

[0093] When the vapor compression system 700 operates in natural heating mode, the controller 422 can monitor the heating capacity periodically, continuously, or at slightly random time intervals. If the current heating capacity deviates from the heating demand, the controller 422 can execute the capacity control program described above to adjust at least one of PRV 432 and VGD 434.

[0094] When the vapor compression system 700 operates in natural heating mode, the controller 422 can further monitor the temperature of the heating fluid entering the evaporator 410 to determine whether natural heating mode can continue. In an exemplary scenario, when the vapor compression system 700 operates in natural heating mode, the temperature of the heating fluid entering the evaporator 410 may drop below a second threshold temperature. In this case, the controller 422 can switch from natural heating mode to conventional heating mode. In another exemplary scenario, the controller 422 may determine that the heating capacity of natural heating mode may be insufficient to meet the heating demand. In this case, the controller 422 can switch from natural heating mode to conventional heating mode.

[0095] When the temperature of the heating fluid entering the evaporator 410 becomes greater than or equal to the second threshold temperature and the heating capacity in the natural heating mode becomes sufficient to meet the heating demand, the controller 422 can switch back from the conventional heating mode to the natural heating mode. In other words, when heating operation is required, the controller 422 can operate the vapor compression system 700 in either the conventional heating mode or the natural heating mode according to the operating conditions of the vapor compression system 700 (e.g., the temperature of the heating fluid entering the evaporator 410, heating demand).

[0096] In some other exemplary scenarios, when the vapor compression system 700 is operating in natural heating mode, the controller 422 can determine that heating operation is no longer required. In this case, the controller 422 can be configured to stop the circulation of refrigerant in the refrigeration circuit 402. To stop the circulation of refrigerant in the refrigeration circuit 402, the controller 422 can be configured to generate a control signal that, when received by the pump 416, causes the pump 416 to stop. Since the compressor 404 has been deactivated and the pump 416 has also been deactivated, the refrigerant circulation in the refrigeration circuit 402 stops.

[0097] although Figure 4 , Figure 5 , Figure 6A , Figure 6B , Figure 7A and Figure 7B The use of separate vapor compression systems (e.g., coolers and boilers) for cooling and heating applications is described; however, in some other embodiments, the HVAC&R system may be a heat pump that provides both heating and cooling functions through a single refrigeration loop (e.g., the same as refrigeration loop 402). In such cases, the functions of vapor compression systems 400 and 700 can be achieved using a single vapor compression system that can maintain a load (e.g., load 442 or load 706) at a preset temperature by cooling or heating. According to embodiments of this disclosure, such a vapor compression system can operate in a conventional cooling mode, a natural cooling mode, a conventional heating mode, or a natural heating mode. Furthermore, in combination with... Figures 10A to 1 0D describes the operation of this vapor compression system.

[0098] Although the vapor compression system 700 is shown to include a pump 416 and a three-way valve 418, the scope of this disclosure is not limited to the illustrated embodiment. In some embodiments, the vapor compression system 700 may not include the pump 416 and the three-way valve 418. In this case, a different pressure differential generator can maintain the flow of liquid refrigerant between the condenser 406 and the evaporator 410. For example, even when the compressor 404 is inactive (e.g., in a closed state), the flow of liquid refrigerant between the condenser 406 and the evaporator 410 can be maintained due to the pressure difference between the condenser 406 and the evaporator 410. The pressure difference between the condenser 406 and the evaporator 410 may be caused by the height difference between the condenser 406 and the evaporator 410. Therefore, when the compressor 404 stops, the refrigerant can naturally flow from the condenser 406 to the evaporator 410, thereby maintaining the flow of refrigerant in the refrigeration circuit 402. According to this embodiment, the vapor compression system 700 can operate in a conventional cooling mode or a natural cooling mode based on ambient temperature conditions without using the pump 416.

[0099] Figure 8 A flowchart illustrating a method 800 for controlling the capability of an HVAC&R system (e.g., a cooler) operating in natural cooling mode according to embodiments of the present disclosure. While method 800 is shown as starting at and flowing from 801 (the starting point of the illustrated process), those skilled in the art will understand that method 800 may be continuous and / or repetitive, or include continuous and / or repetitive components. For example, temperature may be continuously (e.g., periodically) monitored, as shown in block 802, and changes in temperature may alter the operating steps of method 800 or cause portions of method 800 to be repeated.

[0100] In some embodiments, operations 802 to 814 of method 800 may be performed by one or more components of a vapor compression system 400 for a cooling application, such as Figure 4 , Figure 6A and Figure 6B As shown. The illustrated embodiment of method 800 is merely an example. Therefore, it should be understood that any of the various operations can be omitted, reordered, and / or added while remaining within the scope of this disclosure. Furthermore, for the sake of brevity, it is assumed that the controller 422 has determined that a cooling operation is required (e.g., needed) and executes method 800 for performing the cooling operation.

[0101] At point 802, the temperature of the cooling fluid entering condenser 406 is monitored. Controller 422 (e.g., a control circuit system) can be configured to monitor the temperature of the cooling fluid entering condenser 406, such as... Figure 4 , Figure 6A and Figure 6BAs described above, the controller 422 can periodically, at random time intervals or continuously, monitor the temperature of the cooling fluid entering the condenser 406 based on sensing data generated by the temperature sensor S1.

[0102] At point 804, controller 422 can determine whether the temperature of the cooling fluid entering condenser 406 is less than a first threshold temperature value. If at point 804, controller 422 determines that the temperature of the cooling fluid entering condenser 406 is greater than the first threshold temperature value, then control proceeds to point 806.

[0103] At 806, the vapor compression system 400 (e.g., an HVAC&R system) selectively operates in a conventional cooling mode, in which the compressor 404 is active (e.g., the compressor 404 is on). The controller 422 (e.g., a control circuit system) can be configured to selectively operate the vapor compression system 400 in the conventional cooling mode. During the conventional cooling mode, the motor 412 driving the compressor 404 is turned on, so the compressor 404 performs a compression operation on the refrigerant entering the compressor 404. If the vapor compressor system 400 includes a pump 416, the pump 416 is deactivated in the conventional cooling mode. Figure 6A The foregoing description describes the operation of the vapor compression system 400 in normal cooling mode. At 802, the controller 422 continues to monitor the temperature of the cooling fluid entering the condenser 406 in order to detect any temperature changes that may require switching the vapor compression system 400 to natural cooling mode.

[0104] If at 804, controller 422 determines that the temperature of the cooling fluid entering condenser 406 is less than or equal to a first threshold temperature value, control proceeds to 808. At 808, controller 422 may determine whether the cooling capacity of the natural cooling mode is sufficient to meet the cooling demand. If at 808, controller 422 determines that the cooling capacity of the natural cooling mode is insufficient to meet the cooling demand, control proceeds to 806. However, if at 808, controller 422 determines that the cooling capacity of the natural cooling mode is sufficient to meet the cooling demand, control proceeds to 810. As previously described, method 800 may include continuous and repetitive aspects. For example, although the flowchart of method 800 does not show an arrow depicting this point, method 800 may continuously or periodically return (from substantially any point in method 800) to 808 and change operation (e.g., from natural cooling mode to conventional cooling mode) based on whether the natural cooling mode is sufficient to meet the cooling demand.

[0105] At 810, the vapor compression system 400 (e.g., an HVAC&R system) selectively operates in a natural cooling mode, in which the compressor 404 is inactive (e.g., off), and refrigerant circulates through the refrigeration circuit 402, including through the compressor 404 without its activation. A controller 422 (e.g., a control circuit system) can be configured to selectively operate the vapor compression system 400 in the natural cooling mode. During the natural cooling mode, the motor 412 driving the compressor 404 is inactive (e.g., off), and therefore compression operation of the compressor 404 is suspended. Furthermore, when the vapor compression system 400 includes a pump 416, the controller 422 (e.g., a control circuit system) can be configured to activate the pump 416 when the motor 412 driving the compressor 404 stops, so that refrigerant circulates through the refrigeration circuit 402. The activated pump 416 can pressurize the refrigerant to cause it to flow through the refrigeration circuit 402. Furthermore, when the motor 412 driving the compressor 404 stops, the refrigerant flows freely through the impeller 506 of the compressor 404. Figure 6B The foregoing description describes the operation of compressor 404 in natural cooling mode. It should be noted that pump 416 may also represent a pressure differential generator that is not a pump.

[0106] Since cooling demand can vary over time, controller 422 can continue to execute 808 to check whether the cooling capacity of the natural cooling mode is sufficient to meet the cooling demand. If necessary, controller 422 can switch the vapor compression system 400 from natural cooling mode to conventional cooling mode.

[0107] At 812, controller 422 can determine whether the cooling capacity is substantially the same as the cooling demand (e.g., within a threshold, error, or variance). If at 812, controller 422 determines that the cooling capacity is substantially the same as the cooling demand, control remains at 812. However, if at 812, controller 422 determines that the cooling capacity is substantially different from the cooling demand, control proceeds to 814. At 814, PRV 432, VGD 434, or both are adjusted to control the cooling capacity during natural cooling mode. Controller 422 (e.g., a control circuit system) can be configured to adjust PRV 432, VGD 434, or both to control the cooling capacity of vapor compression system 400 during natural cooling mode. Control then proceeds to 812 of method 800. PRV 432 and / or VGD 434 are adjusted to a position where the cooling capacity meets the cooling demand. Figure 6B The foregoing description describes the adjustment of the controller 422 to the PRV 432 and / or VGD 434 to control the cooling capacity of the vapor compression system 400 during natural cooling mode.

[0108] Those skilled in the art will understand that the controller 422 may perform operations 802, 804, 808 and 812 periodically, at substantially random time intervals or continuously based on sensing data received by the controller 422.

[0109] Figure 9 This is a flowchart illustrating a method 900 for controlling the heating capacity of an HVAC&R system (e.g., a boiler) operating in natural heating mode according to embodiments of the present disclosure. While method 900 is shown as starting at 901 (the starting point of the illustrated process) and flowing from there, those skilled in the art will understand that method 900 may be continuous and / or repetitive, or include continuous and / or repetitive components. For example, temperature may be continuously (e.g., periodically) monitored, as shown in block 902, and changes in temperature may alter the operating steps of method 900 or cause parts of method 900 to be repeated.

[0110] In some embodiments, operations 902 to 914 of method 900 may be performed by, for example Figure 7A and Figure 7B The illustrated vapor compression system 700 for heating applications is used to perform this operation. The illustrated embodiment of method 900 is merely an example. Therefore, it should be understood that any of the various operations can be omitted, reordered, and / or added while remaining within the scope of this disclosure. Furthermore, for the sake of brevity, it is assumed that controller 422 has determined that a heating operation is required and executes method 900 for performing the heating operation.

[0111] At point 902, the temperature of the heating fluid entering evaporator 410 is monitored. Controller 422 (e.g., a control circuit system) can be configured to monitor the temperature of the heating fluid entering evaporator 410, such as... Figure 7A and 7B As described above, the controller 422 can periodically, at random time intervals, or continuously based on sensing data generated by the temperature sensor S2 to monitor the temperature of the heating fluid entering the evaporator 410.

[0112] At 904, the controller 422 can determine whether the temperature of the heating fluid entering the evaporator 410 is greater than the second threshold temperature value. If at 904, the controller 422 determines that the temperature of the heating fluid entering the evaporator 410 is less than the second threshold temperature value, then control proceeds to 906.

[0113] At 906, the vapor compression system 700 selectively operates in a conventional heating mode with the compressor 404 active (e.g., compressor 404 is on). The controller 422 (e.g., a control circuit system) can be configured to selectively operate the vapor compression system 700 in the conventional heating mode. During the conventional heating mode, the motor 412 driving the compressor 404 is turned on, so the compressor 404 performs a compression operation on the refrigerant entering the compressor 404. Further, when the vapor compression system 700 includes a pump 416, the pump 416 is deactivated in the conventional heating mode. Figure 7A The foregoing description describes the operation of the vapor compression system 700 in normal heating mode. The controller 422 continues to monitor the temperature of the heating fluid entering the evaporator 410 in order to detect any temperature changes that may require switching the vapor compression system 700 to natural heating mode. If at 904, the controller 422 determines that the temperature of the heating fluid entering the evaporator 410 is greater than or equal to a second threshold temperature value, control proceeds to 908.

[0114] At 908, controller 422 can determine whether the heating capacity of the natural heating mode is sufficient to meet the heating demand. If at 908, controller 422 determines that the heating capacity of the natural heating mode is insufficient to meet the heating demand, control proceeds to 906. However, if at 908, controller 422 determines that the heating capacity of the natural heating mode is sufficient to meet the heating demand, control proceeds to 910. As previously described, method 900 may include continuous and repetitive aspects. For example, although the flowchart of method 900 does not show arrows depicting this, method 900 may continuously or periodically return (from substantially any point in method 900) to 908 and change operation (e.g., from natural heating mode to conventional heating mode) based on whether the natural heating mode is sufficient to meet the heating demand.

[0115] At 910, the vapor compression system 700 selectively operates in a natural heating mode, wherein the compressor 404 is inactive (e.g., off), and refrigerant circulates through the refrigeration circuit 402, including through the compressor 404 without being actuated by it. A controller 422 (e.g., a control circuit system) can be configured to selectively operate the vapor compression system 700 in the natural heating mode. During the natural heating mode, the motor 412 driving the compressor 404 is inactive (e.g., off), and therefore compression operation of the compressor 404 is suspended. Furthermore, when the vapor compression system 700 includes a pump 416, the controller 422 (e.g., a control circuit system) can be configured to activate the pump 416 when the motor 412 driving the compressor 404 stops, so that refrigerant circulates through the refrigeration circuit 402. The activated pump 416 can pressurize the refrigerant to allow it to flow through the refrigeration circuit 402. Additionally, when the motor 412 driving the compressor 404 stops, the refrigerant flows freely through the impeller 506 of the compressor 404. exist Figure 7B The foregoing description describes the operation of compressor 404 in natural heating mode. It should be noted that pump 416 may also represent a pressure differential generator that is not a pump.

[0116] Since heating demand can vary over time, controller 422 can continue to execute 908 to check whether the heating capacity of the natural heating mode is sufficient to meet the heating demand. If necessary, controller 422 can switch the vapor compression system 700 from natural heating mode to conventional heating mode.

[0117] At 912, controller 422 can determine whether the heating capacity is substantially the same as the heating demand (e.g., within a threshold, error, or variance). If at 912, controller 422 determines that the heating capacity is substantially the same as the heating demand, control remains at 912. However, if at 912, controller 422 determines that the heating capacity is not substantially the same as the heating demand, control proceeds to 914.

[0118] At 914, PRV 432, VGD 434, or both are adjusted to control the heating capacity during natural heating mode. Controller 422 (e.g., a control circuit system) can be configured to adjust PRV 432, VGD 434, or both to control the heating capacity of the vapor compression system 700 during natural heating mode. Control then proceeds to 912 of method 900. PRV 432 and / or VGD 434 are adjusted to a position where the heating capacity meets the heating requirements. Figure 7B The foregoing description describes how controller 422 adjusts PRV 432 and / or VGD 434 during natural heating mode to control the heating capacity of vapor compression system 700.

[0119] Those skilled in the art will understand that the controller 422 may perform operations 902, 904, 908 and 912 periodically, at substantially random time intervals or continuously based on sensing data received by the controller 422.

[0120] Figure 10A and Figure 10B This flowchart illustrates a method 1000 for controlling the cooling capacity of an HVAC&R system (e.g., a heat pump) during natural cooling and natural heating modes, according to embodiments of this disclosure. Method 1000 is described as starting at 1001, but can be iterated, repeated, etc. In some embodiments, operations 1002 to 1030 of method 1000 can be performed by one or more components of the heat pump (also referred to as an HVAC&R system). The heat pump can be similar to vapor compression system 400 or vapor compression system 700, except that the heat pump can provide both cooling and heating using a single refrigeration loop 402. During cooling operation, the load is cooled based on heat exchange between the regulating fluid and the refrigerant in evaporator 410, while during heating operation, the load is heated based on heat exchange between the regulating fluid and the refrigerant in condenser 406. The illustrated embodiments of method 1000 are merely examples. Therefore, it should be understood that any of the various operations can be omitted, rearranged, and / or added while remaining within the scope of this disclosure.

[0121] Reference Figure 10A At point 1002, controller 422 can determine whether a cooling operation is required. If controller 422 determines at point 1002 that a cooling operation is required, control proceeds to point 1004. During the cooling operation, regulating fluid through evaporator 410 is used to cool the load. The cooling operation of the heat pump is described using vapor compression system 400.

[0122] At point 1004, the temperature of the cooling fluid entering condenser 406 is monitored. Controller 422 (e.g., a control circuit system) can be configured to monitor the temperature of the cooling fluid entering condenser 406, such as... Figure 4 , Figure 6A and Figure 6B As described above, the controller 422 can periodically, at substantially random time intervals, or continuously based on sensing data generated by the temperature sensor S1, monitor the temperature of the cooling fluid entering the condenser 406.

[0123] At 1006, the controller 422 can determine whether the temperature of the cooling fluid entering the condenser 406 is less than a first threshold temperature value. If at 1006, the controller 422 determines that the temperature of the cooling fluid entering the condenser 406 is greater than the first threshold temperature value, then control proceeds to 1008.

[0124] At 1008, the HVAC&R system selectively operates in a normal cooling mode, in which compressor 404 is active (e.g., on). Controller 422 (e.g., control circuitry) can be configured to selectively operate the HVAC&R system in normal cooling mode. During normal cooling mode, motor 412 driving compressor 404 is active (e.g., on), and therefore compressor 404 performs compression on the refrigerant entering compressor 404. In cases where the vapor compressor system 400 includes pump 416, pump 416 is deactivated in normal cooling mode. Figure 6A The foregoing description describes the operation of the vapor compression system 400 in normal cooling mode. At 1002, the controller 422 continues to monitor the temperature of the cooling fluid entering the condenser 406 in order to detect any temperature changes that may require switching the vapor compression system 400 to natural cooling mode.

[0125] If at 1006, the controller 422 determines that the temperature of the cooling fluid entering the condenser 406 is less than or equal to a first threshold temperature value, then control proceeds to 1010.

[0126] At point 1010, controller 422 can determine whether the cooling capacity of the natural cooling mode is sufficient to meet the cooling requirements. If at point 1010, controller 422 determines that the cooling capacity of the natural cooling mode is insufficient to meet the cooling requirements, then control proceeds to point 1008. However, if at point 1010, controller 422 determines that the cooling capacity of the natural cooling mode is sufficient to meet the cooling requirements, then control proceeds to point 1012.

[0127] At 1012, the HVAC&R system selectively operates in a natural cooling mode, in which compressor 404 is inactive (e.g., off), and refrigerant circulates through refrigeration circuit 402, for example, via compressor 404. Controller 422 (e.g., a control circuit system) can be configured to selectively operate vapor compression system 400 in natural cooling mode. During natural cooling mode, motor 412 driving compressor 404 is inactive (e.g., off), and therefore compression operation of compressor 404 is suspended. Furthermore, when vapor compression system 400 includes pump 416, controller 422 (e.g., a control circuit system) can be configured to activate pump 416 when motor 412 driving compressor 404 stops, so that refrigerant circulates through refrigeration circuit 402. The activated pump 416 can pressurize the refrigerant to cause it to flow through refrigeration circuit 402. Additionally, when motor 412 driving compressor 404 stops, refrigerant flows freely through impeller 506 of compressor 404. Figure 6B The foregoing description describes the operation of compressor 404 in natural cooling mode.

[0128] Since cooling demand can vary over time, controller 422 can continue to execute 1010 to check whether the cooling capacity of the natural cooling mode is sufficient to meet the cooling demand. If necessary, controller 422 can switch the vapor compression system 400 from natural cooling mode to conventional cooling mode.

[0129] At point 1014, controller 422 can determine whether the cooling capacity is substantially the same as the cooling demand (e.g., the same, within a threshold range, within variance, within tolerance). If at point 1014, controller 422 determines that the cooling capacity is substantially the same as the cooling demand, then control remains at point 1014. However, if at point 1014, controller 422 determines that the cooling capacity is substantially different from the cooling demand, then control proceeds to point 1016.

[0130] At 1016, at least one of PRV 432 and VGD 434 is adjusted to control the cooling capacity during natural cooling mode. Controller 422 (e.g., a control circuitry system) can be configured to adjust at least one of PRV 432 and VGD 434 to control the cooling capacity of the HVAC&R system during natural cooling mode. Control then proceeds to 1014. PRV 432 and / or VGD 434 are adjusted to a position where the cooling capacity meets the cooling requirements. Figure 6B The foregoing description describes how controller 422 adjusts PRV 432 and / or VGD 434 during natural cooling mode to control the cooling capacity of the HVAC&R system.

[0131] Those skilled in the art will understand that the controller 422 may perform operations 1004, 1006, 1010 and 1014 periodically, at random time intervals or continuously based on sensing data received by the controller 422.

[0132] If at point 1002, controller 422 determines that heating operation is required but cooling operation is not needed, then control switches to... Figure 10B As shown in 1018. During heating operation, the regulating fluid through condenser 406 is used to cool the load. The heating operation of the heat pump is described using a vapor compression system 700.

[0133] At 1018, the temperature of the heating fluid entering the evaporator 410 is monitored. Controller 422 (e.g., a control circuit system) can be configured to monitor the temperature of the heating fluid entering the evaporator 410, such as... Figure 7A and 7B As described above, the controller 422 can periodically, at random time intervals, or continuously based on sensing data generated by the temperature sensor S2 to monitor the temperature of the heating fluid entering the evaporator 410.

[0134] At 1020, controller 422 can determine whether the temperature of the heating fluid entering evaporator 410 is greater than a second threshold temperature value. If at 1020, controller 422 determines that the temperature of the heating fluid entering evaporator 410 is less than the second threshold temperature value, then control proceeds to 1022.

[0135] At 1022, the vapor compression system 700 selectively operates in a conventional heating mode with the compressor 404 on. The controller 422 (e.g., a control circuit system) can be configured to selectively operate the vapor compression system 700 in the conventional heating mode. During the conventional heating mode, the motor 412 driving the compressor 404 is on, so the compressor 404 performs a compression operation on the refrigerant entering the compressor 404. Further, when the vapor compression system 700 includes a pump 416, the pump 416 is deactivated in the conventional heating mode. Figure 7A The foregoing description describes the operation of the vapor compression system 700 in normal heating mode. The controller 422 continues to monitor the temperature of the heating fluid entering the evaporator 410 in order to detect any temperature changes that may require switching the vapor compression system 700 to natural heating mode.

[0136] If at 1020, the controller 422 determines that the temperature of the heating fluid entering the evaporator 410 is greater than or equal to the second threshold temperature value, then control proceeds to 1024.

[0137] At point 1024, controller 422 can determine whether the heating capacity of the natural heating mode is sufficient to meet the heating demand. If at point 1024, controller 422 determines that the heating capacity of the natural heating mode is insufficient to meet the heating demand, then control proceeds to point 1022. However, if at point 1024, controller 422 determines that the heating capacity of the natural heating mode is sufficient to meet the heating demand, then control proceeds to point 1026.

[0138] At 1026, the HVAC&R system selectively operates in a natural heating mode, in which compressor 404 is inactive (e.g., off), and refrigerant circulates through refrigeration circuit 402, for example, via compressor 404. Controller 422 (e.g., a control circuit system) can be configured to selectively operate vapor compression system 700 in natural heating mode. During natural heating mode, motor 412 driving compressor 404 is inactive (e.g., off), and therefore compression operation of compressor 404 is suspended. Furthermore, when vapor compression system 700 includes pump 416, controller 422 (e.g., a control circuit system) can be configured to activate pump 416 when motor 412 driving compressor 404 stops, so that refrigerant circulates through refrigeration circuit 402. The activated pump 416 can pressurize the refrigerant to cause it to flow through refrigeration circuit 402. Additionally, when motor 412 driving compressor 404 stops, refrigerant flows freely through impeller 506 of compressor 404. Figure 7B The foregoing description describes the operation of compressor 404 in natural heating mode.

[0139] Since heating demand can vary over time, controller 422 can continue to execute step 1024 to check whether the heating capacity of the natural heating mode is sufficient to meet the heating demand. If necessary, controller 422 can switch the vapor compression system 700 from natural heating mode to conventional heating mode.

[0140] At point 1028, controller 422 can determine whether the heating capacity is substantially the same as the heating demand. If at point 1028, controller 422 determines that the heating capacity is the same as the heating demand, then control remains at point 1028. However, if at point 1028, controller 422 determines that the heating capacity is different from the heating demand, then control proceeds to point 1030.

[0141] At 1030, at least one of PRV 432 and VGD 434 is adjusted to control the heating capacity during natural heating mode. Controller 422 (e.g., a control circuit system) can be configured to adjust at least one of PRV 432 and VGD 434 to control the heating capacity of the HVAC&R system during natural heating mode. Control then proceeds to 1028. PRV 432 and / or VGD 434 are adjusted to a position where the heating capacity meets the heating requirements. Figure 7B The foregoing description describes how controller 422 adjusts PRV 432 and / or VGD 434 during natural heating mode to control the heating capacity of vapor compression system 700.

[0142] Those skilled in the art will understand that the controller 422 may perform operations 1018, 1020, 1024 and 1028 periodically, at random time intervals or continuously based on sensing data received by the controller 422.

[0143] Figure 11 This is a flowchart of a method 1100 for preventing conditioning fluid from freezing in an evaporator 410 of an HVAC&R system, according to some embodiments of this disclosure. Method 1100 is depicted as starting at 1101, but may be iterated, repeated, etc. In some embodiments, operations 1102 to 1108 of method 1100 may be performed by one or more components of a vapor compression system 400, 700 (e.g., an HVAC&R system). The illustrated embodiments of method 1100 are merely examples. Therefore, it should be understood that any of the various operations may be omitted, reordered, and / or added while remaining within the scope of this disclosure.

[0144] At 1102, controller 422 can determine whether the regulating fluid can freeze in the tubes of evaporator 410. This determination can be based on temperature measurements, liquid level (e.g., in the evaporator), etc., detected directly or indirectly by any of a variety of sensors. If at 1102, controller 422 determines that the regulating fluid is unlikely to freeze in the tubes of evaporator 410, control remains at 1102. However, if at 1102, controller 422 determines that there is a possibility that the regulating fluid may freeze in the tubes of evaporator 410, control proceeds to 1104.

[0145] At 1104, at least one of PRV 432, VGD 434, and expansion device 408 is adjusted to a fully closed position. Controller 422 can be configured to adjust at least one of PRV 432, VGD 434, expansion device 408, and / or bypass valve 411 to a fully closed position to prevent refrigerant from flowing into evaporator 410, which in turn prevents the regulating fluid from freezing in the pipes of evaporator 410. Figure 6B The foregoing description describes the operation of controller 422 to prevent the regulating fluid from freezing in the tubes of evaporator 410.

[0146] At 1106, controller 422 can again determine whether the regulating fluid can freeze in the tubes of evaporator 410. If at 1106, controller 422 determines that the regulating fluid still has the possibility of freezing, control remains at 1106. However, if at 1106, controller 422 determines that the regulating fluid cannot freeze, control proceeds to 1108.

[0147] At 1108, at least one of PRV 432, VGD 434, and expansion device 408 is adjusted to a fully or partially open position. Controller 422 can be configured to adjust at least one of PRV 432, VGD 434, and expansion device 408 to a fully or partially open position to restart refrigerant circulation. Control then returns to 1102.

[0148] This disclosure provides numerous technical advancements and advantages. For example, the capacity control program and / or algorithm implemented by controller 422 allows control of cooling capacity during natural cooling operation and / or heating capacity during natural heating operation. In conventional natural cooling / heating operation, the compressor, although inactive (e.g., off), is typically bypassed. However, in this disclosure, the refrigerant passes through compressor 404, which is inactive (e.g., off), and flow reduction devices (e.g., PRV 432 and / or VGD 434) of compressor 404 are used to control the cooling / heating capacity. In other words, the HVAC&R system of this disclosure is capable of controlling cooling / heating capacity during natural cooling / heating mode according to varying ambient temperatures. The HVAC&R system of this disclosure can have numerous applications, for example, in submarines where the temperature of the evaporator conditioning fluid may be very low (e.g., -2°C).

[0149] The construction and arrangement of the systems and methods shown in the various exemplary embodiments are illustrative only. Although only a few embodiments are described in detail in this disclosure, many modifications are possible (e.g., variations in the size, scale, structure, shape and proportion of various elements, parameter values, installation arrangements, use of materials, color, orientation, etc.). For example, the positions of elements may be reversed or otherwise varied, and the nature or number or position of discrete elements may be altered or varied. Therefore, all such modifications are intended to be included within the scope of this disclosure. The order or sequence of any process or method steps may be varied or reordered according to alternative embodiments. Other substitutions, modifications, alterations, and omissions may also be made in terms of the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of this disclosure.

[0150] This disclosure contemplates methods, systems, and program products on any machine-readable medium for performing various operations. Embodiments of this disclosure may be implemented using existing computer processors, or by a dedicated computer processor for (incorporated for the purposes of implementing embodiments of this disclosure or for another purpose), or by a hardwired system. Embodiments within the scope of this disclosure include program products comprising machine-readable media for carrying or storing machine-executable instructions or data structures thereon. Such machine-readable media can be any available medium accessible by a general-purpose or special-purpose computer or other machine having a processor. For example, such machine-readable media may include RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disc storage devices, magnetic disk storage devices or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of machine-executable instructions or data structures and is accessible by a general-purpose or special-purpose computer or other machine having a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data that cause a general-purpose computer, special-purpose computer, or special-purpose processing machine to perform a function or group of functions.

[0151] Although the accompanying drawings show a specific order of method steps, the order of steps may differ from that depicted. Furthermore, two or more steps may be performed simultaneously or partially simultaneously. Such variations will depend on the chosen software and hardware system and the designer's choices. All such variations are within the scope of this disclosure. Similarly, the software implementation can be accomplished using standard programming techniques with rule-based logic and other logic to perform various connection steps, processing steps, comparison steps, and decision steps.

Claims

1. A heating, ventilation, air conditioning and / or cooling (HVAC&R) system, comprising: - A refrigeration circuit, comprising an evaporator, a compressor, and a condenser, the refrigeration circuit being configured to circulate a refrigerant and facilitate heat exchange between the refrigerant and a regulating fluid; - A pre-rotating vane (PRV) at the compressor inlet, a variable geometry diffuser (VGD) at the compressor outlet, or both the pre-rotating vane and the variable geometry diffuser; and - A control circuit system, the control circuit system being configured to: - The HVAC&R system may be selectively operated in either a conventional cooling mode or a natural cooling mode, wherein: - In the normal cooling mode, the control circuit system is configured to control the compressor to be active in order to compress the refrigerant; - In the natural cooling mode, the control circuitry is configured to keep the compressor inactive, allowing the refrigerant to circulate through the compressor via a pressure differential generator; and - Adjust the PRV, the VGD, or both to control the cooling capacity of the HVAC&R system in the natural cooling mode.

2. The HVAC&R system according to claim 1, The compressor mentioned above includes: - A rotation axis, which is configured to rotate about a rotation axis; - An electric motor configured to drive the rotating shaft; as well as - An impeller, which is connected to the rotating shaft.

3. The HVAC&R system according to claim 2, The control circuitry is configured to stop the motor in conjunction with entering the natural cooling mode to place the compressor in the inactive state.

4. The HVAC&R system according to claim 3, The pressure differential generator includes thermosiphon operation, and in the natural cooling mode, the refrigerant flows through the impeller.

5. The HVAC&R system according to any one of claims 1 to 4, The control circuitry is configured to operate the HVAC&R system in natural cooling mode based on the temperature of the regulating fluid entering the condenser being within a specified range.

6. The HVAC&R system according to claim 5, It includes a temperature sensor configured to detect the temperature of the regulating fluid entering the condenser at the condenser inlet and to provide a sensor signal indicating the temperature to the control circuitry.

7. The HVAC&R system according to claim 5 or 6, The range includes temperature values ​​that are less than or equal to the threshold temperature.

8. The HVAC&R system according to any one of claims 1 to 7, The control circuitry is configured to adjust the PRV, the VGD, or both to a closed position based on conditions indicating that the regulating fluid freezes in one or more tubes of the evaporator.

9. The HVAC&R system according to claim 5, 6, or 7, It includes an expansion device, wherein the control circuitry is configured to adjust the expansion device to a closed position based on conditions indicating that the regulating fluid may freeze in one or more tubes of the evaporator.

10. The HVAC&R system according to any one of claims 1 to 9, The control circuitry is configured to control the cooling capacity of the HVAC&R system in the natural cooling mode by adjusting the PRV, the VGD, or both between a corresponding fully open and fully closed position.

11. The HVAC&R system according to any one of claims 1 to 10, The differential pressure generator includes a pump, and the control circuitry is configured to activate the pump in conjunction with activating the natural cooling mode.

12. A method for controlling a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system, the HVAC&R system including a refrigeration circuit comprising an evaporator, a compressor, and a condenser, the refrigeration circuit being configured to circulate a refrigerant and facilitate heat exchange between the refrigerant and a conditioning fluid, the method comprising: - The HVAC&R system is selectively operated in either a conventional cooling mode or a natural cooling mode via a control circuit system, wherein: - In the natural cooling mode, the compressor's compression operation is inactive, and the refrigerant circulates through the compressor, and - In the normal cooling mode, the compressor's compression operation is active, and the refrigerant is actuated by the compressor through the refrigerant circuit; and - The cooling capacity of the HVAC&R system in the natural cooling mode is controlled by adjusting the pre-rotating vane (PRV) and / or the variable geometry diffuser (VGD) via the control circuit system, wherein the PRV is located at the inlet of the compressor.

13. The method according to claim 12, It includes controlling the pump via the control circuit system to circulate the refrigerant in the natural cooling mode.

14. The method according to claim 12 or 13, It includes closing the expansion valve between the condenser and the evaporator based on the detection of conditions indicating possible freezing of the regulating fluid.

15. The method according to any one of claims 12 to 14, It includes selectively operating the HVAC&R system in either a conventional heating mode or a natural heating mode via the control circuitry system, wherein: - In the natural heating mode, the compressor's compression operation is inactive, and the refrigerant circulates through the compressor, and - In the normal heating mode, the compressor's compression operation is active, and the refrigerant is actuated by the compressor through the refrigerant circuit.

16. A heating, ventilation, air conditioning and / or cooling (HVAC&R) system, comprising: - A compressor, the compressor comprising a pre-swirl vane (PRV) at the inlet of the compressor, a variable geometry diffuser (VGD) at the outlet of the compressor, or both the pre-swirl vane and the variable geometry diffuser; and - A control circuit system, the control circuit system being configured to: - The HVAC&R system can be selectively operated in either a conventional heating mode or a natural heating mode, wherein: - In the natural heating mode, the control circuit system is configured to control the compressor to be inactive, such that refrigerant circulates through the compressor via a pressure differential generator, and - In the conventional heating mode, the control circuit system is configured to control the compressor to be active, causing the refrigerant to circulate through the compressor; and - Adjust the PRV, the VGD, or both to control the heating capacity of the HVAC&R system in the natural heating mode.

17. The HVAC&R system according to claim 16, It includes an evaporator and a condenser, wherein the compressor, the evaporator and the condenser form at least a portion of a refrigeration circuit that circulates the refrigerant.

18. The HVAC&R system according to claim 17, The control circuitry is configured to operate the HVAC&R system in the natural heating mode based on the temperature of the regulating fluid at the inlet of the evaporator being greater than or equal to a first threshold.

19. The HVAC&R system according to claim 18, It further includes a temperature sensor, which is configured to: - Detect the temperature of the heating fluid at the inlet of the evaporator; and - Provide the control circuit system with a sensor signal indicating the detected temperature.

20. The HVAC&R system according to any one of claims 16 to 19, The differential pressure generator includes a pump, and the control circuitry is configured to activate the pump in conjunction with the activation of the natural heating mode to circulate the refrigerant.

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