Ultrahigh-temperature heat pump

Abstract

A heating, ventilation, air conditioning, and refrigeration (HVACR) system includes an inspiration regulating valve fluidly connecting an outlet of an evaporator to an inspiration port of a compressor. And an intake regulating valve for controlling refrigerant flow from an outlet of the evaporator to an intake port of the compressor and controlling refrigerant pressure drop based on a result of monitoring at least one of (i) a refrigerant pressure difference at the expansion device and (ii) a refrigerant superheat degree downstream of the intake regulating valve.

Description

Technical Field

[0001] This disclosure generally relates to an ultra-high temperature heat pump. More specifically, this disclosure relates to an ultra-high temperature heat pump that utilizes a heat source to provide hot water. Background Technology

[0002] Heating, ventilation, air conditioning, and refrigeration (HVACR) systems may include a heat pump that uses a heat source to provide hot water. In the refrigerant circuit of the heat pump, refrigerant flows through an evaporator and absorbs heat from the heat source, becoming a low-pressure refrigerant that can be applied to a compressor. The refrigerant from the compressor flows through a condenser and releases heat to a process fluid (e.g., water) to provide hot water. Summary of the Invention

[0003] This disclosure generally relates to a heating, ventilation, air conditioning, and refrigeration (HVACR) system that includes a heat pump. More specifically, this disclosure relates to a heat pump that utilizes a heat source to provide, for example, hot water or steam.

[0004] The embodiments disclosed herein provide an HVACR system including an ultra-high temperature heat pump capable of providing hot water (e.g., at 120°C or above) or steam using a heat source (e.g., at 40°C or above). The embodiments described herein can improve the reliability, stability, and efficiency of the ultra-high temperature heat pump by addressing issues including, for example, wet compression and / or low suction / discharge superheat during system startup, and oil viscosity during stable operation.

[0005] In summary, in one embodiment, this disclosure describes a heating, ventilation, air conditioning, and refrigeration (HVACR) system. The HVACR system includes a refrigerant circuit and a suction regulating valve. The refrigerant circuit includes an evaporator, a compressor, an expansion unit, and a condenser for operating refrigerant therein. The suction regulating valve fluidly connects the outlet of the evaporator to the suction port of the compressor. The suction regulating valve is configured to control the refrigerant flow rate from the outlet of the evaporator to the suction port of the compressor. The system also includes a controller configured to monitor at least one of the following: (i) the pressure differential at the expansion unit and (ii) the refrigerant superheat downstream of the suction regulating valve, and adjust the suction regulating valve based on the monitoring results to control the refrigerant pressure drop from the outlet of the evaporator to the suction port of the compressor.

[0006] In another embodiment, this disclosure describes a method for controlling a heating, ventilation, air conditioning, and refrigeration (HVACR) system, the system including a refrigerant circuit comprising an evaporator, a compressor, an expansion unit, and a condenser for operating refrigerant therein. The method includes connecting the outlet fluid of the evaporator to the suction port of the compressor via a suction regulating valve. The suction regulating valve is configured to control the refrigerant flow rate from the evaporator to the suction port of the compressor. The method further includes monitoring at least one of the following: (i) the pressure differential at the expansion unit and (ii) the refrigerant superheat downstream of the suction regulating valve, and adjusting the suction regulating valve based on the monitoring results to control the refrigerant pressure drop from the evaporator outlet to the suction port of the compressor.

[0007] Various aspects and advantages of exemplary embodiments of this disclosure have been summarized. The above summary is not intended to describe every illustrated embodiment. Other features and aspects will become apparent from the following detailed description and accompanying drawings. Attached Figure Description

[0008] Reference is made to the accompanying drawings, which form part of this disclosure, and which illustrate embodiments of the systems and methods described herein that can be practiced.

[0009] Figure 1 A schematic diagram of a refrigerant circuit that can be implemented in an HVACR system according to one embodiment is shown.

[0010] Figure 2 A schematic diagram of a control system according to one embodiment is shown.

[0011] Figure 3 This is a schematic diagram of an ultra-high temperature heat pump according to one embodiment.

[0012] Figure 4 This is a flowchart of a method for controlling a heat pump according to one embodiment.

[0013] Figure 5 This is a flowchart of a method for controlling a heat pump during a startup phase or a mode change phase, according to one embodiment.

[0014] Figure 6 This is a flowchart of a method for controlling a reheater of a heat pump according to one embodiment.

[0015] Figure 7 This is a flowchart of a method for controlling oil cooling and refrigerant superheat in a heat pump according to one embodiment.

[0016] Throughout the text, the same reference numerals denote the same parts. Detailed Implementation

[0017] In the following detailed description, reference is made to the accompanying drawings, which form part of this specification. In the drawings, like symbols generally identify like parts unless the context otherwise indicates. Furthermore, unless otherwise specified, the description of each successive drawing may refer to features in one or more preceding drawings to provide a clearer context and a more substantial explanation of the present exemplary embodiments. However, the exemplary embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that aspects of this disclosure, as generally described herein and shown in the description of the drawings, can be arranged, substituted, combined, separated, and designed in a variety of different configurations, all of which are explicitly contemplated herein.

[0018] Specific embodiments of this disclosure are described herein with reference to the accompanying drawings; however, it should be understood that the disclosed embodiments are merely examples of this disclosure and may be implemented in various forms. Well-known functions or constructions have not been described in detail to avoid obscuring this disclosure with unnecessary detail. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as the basis for the claims and as a representative basis for teaching those skilled in the art to adopt this disclosure differently with virtually any suitable detailed construction. In this specification and the accompanying drawings, the same reference numerals denote elements that can perform the same, similar, or equivalent functions.

[0019] Furthermore, this disclosure can be described in terms of functional block components and various processing steps. It should be understood that such functional blocks can be implemented by any number of hardware and / or software components configured to perform the specified functions.

[0020] The scope of this disclosure should be determined by the appended claims and their legal equivalents, and not by the examples given herein. For example, the steps recited in any method claim may be performed in any order, and are not limited to the order presented in the claims. Furthermore, unless specifically described herein as “critical” or “essential,” no element is indispensable for the implementation of this disclosure.

[0021] As described in this article, "suction superheat" refers to the temperature difference between the temperature of the refrigerant vapor at the compressor suction line and its saturation temperature at the corresponding suction pressure. It can be used as a parameter for evaluating and controlling the performance of HVAC systems. Suction superheat can be measured using a temperature sensor placed at the compressor suction line. The measured temperature can be compared with the saturation temperature at the corresponding suction pressure to determine the temperature difference (i.e., superheat).

[0022] As described in this article, "discharge superheat" refers to the temperature difference between the temperature of the refrigerant vapor at the compressor discharge line and its saturation temperature at the corresponding discharge pressure. It can be used as a parameter for evaluating and controlling the performance of HVAC systems. Discharge superheat can be measured using a temperature sensor placed at the compressor discharge line. The measured temperature can be compared with the saturation temperature at the corresponding discharge pressure to determine the temperature difference (i.e., superheat).

[0023] As described herein, a “thermosiphon” or “thermosiphon device” can refer to a passive heat exchange mechanism that is filled with a working fluid, such as a refrigerant like hydrofluorocarbons (HFCs) or halon refrigerants like R-134a. The working fluid (e.g., via its own gravity) flows into the heat exchange mechanism, receives heat from a relatively high-temperature process fluid (e.g., oil from an oil separator), evaporates, and leaves the heat exchange mechanism (e.g., via a pressure gradient). The process continues as the high-temperature process fluid passes through the heat exchange mechanism to transfer heat to the working fluid and drive the process. In one embodiment, a thermosiphon device may include a brazed plate (BP) heat exchanger.

[0024] The embodiments described herein maintain suction superheat at a desired level to enable efficient and reliable operation of the compressor and refrigeration system. Proper suction / discharge superheat prevents liquid refrigerant from entering / leaving the compressor and avoids so-called "wet compression," which can damage the compressor and / or reduce system efficiency or reliability.

[0025] The embodiments disclosed herein provide HVACR systems including ultra-high temperature heat pumps. The embodiments described herein apply a low-pressure refrigerant to a compressor to provide hot water (e.g., at 120°C or above) or steam using a heat source (e.g., at a temperature of 40°C or above). The low-pressure refrigerant may have a relatively low pressure at a given saturation temperature, such as R245fa and R1233zdE(E). R410A is an exemplary high-pressure refrigerant. R134a is an exemplary medium-pressure refrigerant. The embodiments described herein can improve the reliability, stability, and efficiency of ultra-high temperature heat pumps by addressing issues including, for example, wet compression and / or low suction / discharge superheat during system startup or transition phases, and oil viscosity during steady-state operation.

[0026] The "start-up phase" can refer to the initial stage when a refrigeration system (e.g., a heat pump) restarts after being turned on or off. During the start-up phase, the compressor starts, initiating the circulation of the working fluid (e.g., refrigerant) in the refrigeration system.

[0027] The "stable operation phase" refers to the stage in which the refrigeration system operates under its expected and relatively stable conditions. After the startup phase, the system can enter the stable operation phase.

[0028] The "transition phase" can refer to a stage in a refrigeration system where operating conditions / states or system requirements undergo relatively significant / drastic changes. For example, when a refrigeration system changes its operating mode (e.g., from heating to cooling) or the temperature of the process fluid changes drastically (e.g., water temperature changes from 70°C to 100°C), the system may be in a transition phase. It should be understood that a refrigeration system (e.g., a heat pump) can have multiple operating phases, including a start-up phase, a stable operating phase, and a transition phase. Operating parameters such as pressure and temperature are relatively stable during the stable operating phase. That is, although operating parameters may change or fluctuate during the stable operating phase, they are not as drastic as during the start-up and / or transition phases.

[0029] Figure 1 This is a schematic diagram of a refrigerant circuit 100 according to one embodiment. The refrigerant circuit 100 includes a compressor 120, a condenser 140, an expansion device 160, and an evaporator 180. The refrigerant circuit 100 may also include a controller (e.g., Figure 2 The controller 145 is configured to control the operation of the compressor 120, condenser 140, expansion unit 160, evaporator 180 and / or other loop components of the refrigerant loop 100.

[0030] Refrigerant circuit 100 can typically be used in various systems for controlling environmental conditions (e.g., temperature, humidity, air quality, etc.) in a regulated space. In one embodiment, refrigerant circuit 100 can be used to generate a cold / hot fluid (e.g., water). The regulated space can be a space within an office building, commercial building, factory, laboratory, data center, residential building, etc. In one embodiment, refrigerant circuit 100 can be configured as a cooling system (e.g., an air conditioning system) capable of operating in a heating mode or a cooling mode. In one embodiment, refrigerant circuit 100 can be configured as a heat pump capable of operating in a heating mode. It should be understood that refrigerant circuit 100 can be configured to operate in a heating mode and switch to a cooling mode, or operate in a cooling mode and switch to a heating mode.

[0031] Compressor 120, condenser 140, expansion device 160, and evaporator 180 may be fluidly connected. The term "expansion device" as used herein may also be referred to as an expander. In one embodiment, expansion device 160 may be an expansion valve, expansion plate, expansion container, orifice, or other expansion mechanism of this type. It should be understood that expansion device 160 may be any suitable type of expansion device in the art for expanding a working fluid to reduce its pressure and temperature.

[0032] Refrigerant circuit 100 is an example and can be configured to include more or fewer components. For example, in one embodiment, refrigerant circuit 100 may include other components such as, but not limited to, an energy-efficient heat exchanger, one or more flow control devices (e.g., valves, pumps, etc.), a receiver box, a dryer, a suction-liquid heat exchanger (e.g., a reheater), etc.

[0033] Refrigerant circuit 100 can operate according to generally known principles. Refrigerant circuit 100 can be configured to heat and / or cool a liquid process fluid. The liquid process fluid can be a heat transfer fluid or medium (e.g., a liquid such as, but not limited to, water). Refrigerant circuit 100 can generally represent a liquid cooler system. Alternatively, refrigerant circuit 100 can be configured to heat and / or cool a gaseous process fluid (e.g., a heat transfer medium) or fluid (e.g., a gas such as, but not limited to, air), in which case refrigerant circuit 100 can generally represent an air conditioner and / or a heat pump.

[0034] In some embodiments, the refrigerant circuit 100 may operate as a vapor compression circuit, such that the compressor 120 compresses the working fluid (e.g., a heat transfer fluid, such as, but not limited to, a refrigerant) from a relatively low-pressure gas to a relatively high-pressure gas. The relatively high-pressure gas is at a relatively high temperature and is discharged from the compressor 120 and flows through the condenser 140. According to generally known principles, the working fluid flows through the condenser 140 and dissipates heat to the process fluid (e.g., water, air, etc.), thereby cooling the working fluid. In one embodiment, the process fluid may be water heated to provide hot water, for example, water (steam) at a temperature exceeding 120°C. The cooled working fluid, now in liquid form, flows to the expansion device 160, which can reduce the pressure of the working fluid. Thus, a portion of the working fluid is converted to a gaseous form. The working fluid, now a mixture of liquid and gas, flows to the evaporator 180. The working fluid flows through the evaporator 180 and absorbs heat from the process fluid (e.g., a heat transfer medium, such as, but not limited to, water, a solution, air, etc.), heating the working fluid and converting it to a gaseous form. In one embodiment, the process fluid is water at a temperature of, for example, 40°C or higher. The process fluid (e.g., water at 40°C or higher) serves as a heat source for evaporating the working fluid. The gaseous working fluid is then returned to the compressor 120. The above process continues while the heat transfer circuit is operating, for example, providing hot water or steam in heating mode (e.g., when the compressor 120 is activated).

[0035] In some embodiments, the refrigerant circuit 100 may be configured to operate as a free cooling / heating circuit to control one or more environmental conditions in a regulated space. The free cooling / heating circuit may include a first heat exchanger and a second heat exchanger fluidly connected by a working fluid. The first and second heat exchangers of the free cooling / heating circuit may be dedicated heat exchangers other than those in the refrigerant circuit 100 having a compressor 120, a condenser 140, an expander 160, and an evaporator 180. In some embodiments, the first and second heat exchangers may share, for example, the condenser 140 and the evaporator 180, such that the refrigerant circuit 100 can operate as a free cooling / heating circuit or a vapor compression circuit.

[0036] In some embodiments, a first heat exchanger can exchange heat between a working fluid and an ambient fluid (e.g., outdoor air). The first heat exchanger can be located in a position suitable for exchanging heat with the ambient fluid. This location may include the roof of the conditioned space. A second heat exchanger can be an evaporator 180 for exchanging heat between the working fluid and a fluid in the conditioned space. The fluid in the conditioned space may be, for example, indoor air. In some embodiments, the first heat exchanger can be a condenser 140.

[0037] In cooling operation, the first heat exchanger can release heat to the ambient fluid and cool the working fluid. A pump can move the cooled working fluid to a second heat exchanger to exchange heat with the fluid in the regulated space, heating the working fluid so that it can be cooled again by the ambient fluid. In some embodiments, during cooling operation, the temperature of the ambient fluid may be lower than the temperature of the fluid in the regulated space. The pump can circulate the working fluid between the first and second heat exchangers to move heat from the ambient fluid to the fluid in the regulated space. In some embodiments, during heating operation, the temperature of the ambient fluid may be higher than the temperature of the fluid in the regulated space. The working fluid can be any heat transfer fluid, such as a refrigerant, water, an aqueous solution, ethylene glycol, etc.

[0038] Figure 2 A schematic diagram of a control system 130 according to one embodiment is shown. The control system 130 includes a controller 145 configured to control an intake regulating valve 190, for example... Figure 3 The suction regulating valve 350 is located in the refrigerant circuit 300. The suction regulating valve 190 is controlled by a controller 145 and is configured to control the flow from the evaporator (e.g., Figure 3 The outlet of the evaporator 350) is connected to the compressor (e.g., Figure 3 The refrigerant pressure drop at the suction port of the compressor (310) is used to obtain the desired / required pressure difference between the suction port and the discharge port of the compressor. Figures 3-5The illustrated embodiment will further describe in detail the operation of the suction regulating valve in the refrigeration system and its related control methods.

[0039] The controller 145 can receive various sensing data from one or more sensors 182 distributed throughout the HVACR system and generate control signals based on the received sensing data. The one or more sensors 182 may include, for example, one or more temperature sensors, one or more pressure sensors, etc. The sensors can be located at various points within the refrigeration system.

[0040] Controller 145 typically represents refrigerant circuit 100 ( Figure 1 The hardware aspects of the controller are described below. Controller 145 is an example and not intended to be limiting. Controller 145 includes a processor 150, memory 155, input / output 175, and storage 165. It should be understood that controller 145 may include one or more additional components.

[0041] Processor 150 can retrieve and execute programming instructions stored in memory 155 and / or storage 165. Processor 150 can also store and retrieve application data residing in memory 155. Processor 150 can be a single processor, multiple processors, a coprocessor, or a single processor with multiple processing cores. In some embodiments, processor 150 can be a single-threaded processor. In some embodiments, processor 150 can be a multi-threaded processor.

[0042] Interconnect 170 is used to transfer programming instructions and / or application data between processor 150, memory 155, storage 165, and input / output 175. Interconnect 170 may be, for example, one or more buses.

[0043] Typically includes memory 155 to represent random access memory, such as, but not limited to, static random access memory (SRAM), dynamic random access memory (DRAM), flash memory, suitable combinations thereof, etc. In some embodiments, memory 155 may be volatile memory. In some embodiments, memory 155 may be non-volatile memory.

[0044] Input / output 175 may include wired and wireless connectivity. In one embodiment, input / output 175 may transmit data and / or control signals via wires, fiber optic cables, or the like.

[0045] The aspects described herein may be embodied in a system, method, or computer-readable medium. In one embodiment, the described aspects may be implemented in hardware, software (including firmware, etc.), or a combination thereof. Some aspects may be implemented in a computer-readable medium, including computer-readable instructions for execution by a processor. Any combination of one or more computer-readable media may be used.

[0046] The computer-readable medium may include a computer-readable signal medium and / or a computer-readable storage medium. A computer-readable storage medium may include any tangible medium capable of storing a computer program for a programmable processor to perform the functions described herein by manipulating input data and generating output. A computer program is a set of instructions that can be used directly or indirectly in a computer system to perform a specific function or determine a specific result.

[0047] Examples of computer-readable storage media include, but are not limited to, floppy disks; hard disks; random access memory (RAM); read-only memory (ROM); semiconductor storage devices, such as, but not limited to, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, etc.; portable optical disc read-only memory (CD-ROM); optical storage devices; magnetic storage devices; other similar devices; or suitable combinations thereof.

[0048] Computer-readable signal media may include propagated data signals having computer-readable instructions. Examples of propagated signals include, but are not limited to, optical propagated signals, electromagnetic propagated signals, etc. Computer-readable signal media may include any computer-readable medium that is not a computer-readable storage medium, which may propagate a computer program for use by a programmable processor to perform the functions described herein by manipulating input data and generating output.

[0049] Figure 3 This is a schematic diagram of a refrigerant circuit 300 according to one embodiment, which may be an ultra-high temperature heat pump implemented in an HVACR system. The heat pump 300 includes a refrigerant circuit comprising a compressor 310, an evaporator 320, an expansion device 330, and a condenser 340, wherein a working fluid (e.g., refrigerant) operates.

[0050] Compressor 310 may include a compression mechanism and a motor. Compressor 310 may include an intake regulating valve (e.g., intake regulating valve 350) at the inlet (i.e., suction port 310a) for controlling the refrigerant vapor flow into compressor 310, and an exhaust check valve at the outlet (i.e., discharge port 310b) for preventing backflow when the refrigerant circuit is shut down. One or more pressure and temperature sensors may be located at or near discharge port 310b to measure refrigerant pressure and temperature. In one embodiment, compressor 310 is a screw compressor. It should be understood that compressor 310 may be any suitable type of compressor other than a screw compressor.

[0051] Compressor 310 may also include an oil system to provide lubrication and reduce friction and wear between moving parts. Oil separator 315 is connected to compressor 310 via discharge line 313 to separate oil from refrigerant vapor. The separated oil is returned to compressor 310 via a thermosiphon circuit to cool it, as will be described further below. The refrigerant vapor then continues to condenser 340 and dissipates heat to the process fluid, thereby cooling the refrigerant. Figure 3 In the illustrated embodiment, the process fluid is water, which enters the condenser 340 via inlet 341 and exits the condenser 340 after heating via outlet 343. In one embodiment, the water may be heated to, for example, 120°C or higher. Hot water may be injected into a flash tank (not shown) to generate steam. Both inlet 341 and outlet 343 may include temperature sensors for measuring their respective water temperatures. The cooled refrigerant liquid then flows to an expansion device 330, which reduces the pressure of the refrigerant and converts the refrigerant liquid into a liquid-gas mixture before flowing to the evaporator 320.

[0052] The refrigerant flows through evaporator 320 and absorbs heat from the process fluid, which heats the working fluid and converts it into a gaseous form. The gaseous refrigerant then leaves evaporator 320 via outlet 320a. Figure 3 In the illustrated embodiment, the process fluid is water, which enters the evaporator 320 via inlet 321 and serves as a heat source for the refrigerant in the evaporator 320. The cooled water exits the evaporator 320 via outlet 323. Both inlet 321 and outlet 323 may include temperature sensors for measuring the respective water temperature. In one embodiment, the temperature of the heat source (e.g., water) may be, for example, 40°C or above, or between about 40°C and about 85°C.

[0053] It should be understood that the process fluid of evaporator 320 can be any suitable process fluid other than water as a heat source. The choice of process fluid may depend on various factors, such as the system load (e.g., the amount of hot water or steam required at condenser 340). In one embodiment, water at a temperature of 40°C or above (e.g., between about 40°C and about 85°C) can be used as a heat source for any tonnage cooler to provide / generate any required amount of hot water or steam.

[0054] The suction regulating valve 350 connects the outlet 320a of the evaporator 320 to the suction port 310a of the compressor 310. The suction regulating valve 350 is configured to control the refrigerant flow from the outlet 320a of the evaporator 320 to the suction port 310a of the compressor 310. The suction regulating valve 350 can be any type of valve capable of controlling the refrigerant flow, including, for example, a butterfly valve, a solenoid valve, a ball valve, etc. The suction regulating valve 350 can continuously or discretely regulate the refrigerant flow between a fully open state and a fully closed state. For example, a butterfly valve can regulate the fluid flow by adjusting between multiple states, including, for example, a fully open state allowing maximum flow, a fully closed state completely cutting off flow, and one or more partially closed / open states between the fully open and fully closed states.

[0055] exist Figure 3 In the illustrated embodiment, the suction regulating valve 350 is shown as a stand-alone device and is located on the suction line 352 that fluidly connects the outlet 320a of the evaporator 320 to the suction port 310a of the compressor 310. It should be understood that suitable suction regulating valves described herein can have various configurations and / or locations, as long as the suction regulating valve is capable of generating and controlling the refrigerant pressure drop from the evaporator to the compressor, which are fluidly connected via the suction line. In one embodiment, the suction regulating valve 350 may be mounted at the suction port 310a of the compressor 310 or at the outlet 320a of the evaporator 320. In one embodiment, the suction regulating valve 350 may be integrated as a component of the compressor 310 or the evaporator 320, rather than as a stand-alone device.

[0056] The heat pump 300 also includes a control system or controller (e.g., Figure 2The controller 145 can monitor at least one of the following: (i) the refrigerant pressure differential at the expansion unit 330; and (ii) the refrigerant superheat downstream of the suction regulating valve 350 (e.g., refrigerant discharge superheat). Based on the results of this monitoring, the controller can adjust the suction regulating valve 350 to control the refrigerant pressure drop from the outlet 320a of the evaporator 320 to the suction port 310a of the compressor 310, and obtain the desired / required level of refrigerant pressure differential between the inlet and outlet (i.e., 310a and 310b) of the compressor 310, which will be discussed below. Figure 4 and Figure 5 Further details are provided below.

[0057] The heat pump 300 also includes a reheater 370, configured to perform and control heat exchange between the relatively high-temperature refrigerant liquid from the condenser 340 and the relatively low-temperature refrigerant vapor from the suction regulating valve 350. The reheater 370 may include any suitable type of heat exchanger for heat exchange. The high-temperature refrigerant liquid leaving the condenser 340 is directed to the heat exchanger or reheater 370. The low-temperature refrigerant vapor from the evaporator 320 is also directed to the heat exchanger or reheater 370. The heat exchange cools the high-temperature refrigerant liquid to achieve greater subcooling, while the low-temperature refrigerant vapor gains heat and begins to warm up. The heated refrigerant vapor is directed to the suction port 310a of the compressor 310. The cooled refrigerant may be directed to a downstream throttling valve or pressure-reducing device, such as the evaporator 330.

[0058] exist Figure 3 In the illustrated embodiment, reheater 370 is shown as a separate device fluidly connecting evaporator 320 and condenser 340. It should be understood that suitable reheaters described herein can have various configurations and / or locations, as long as the reheater is capable of heat exchange between a high-temperature refrigerant fluid (e.g., liquid) from condenser 340 and a low-temperature refrigerant fluid (e.g., vapor) from evaporator 320. In one embodiment, reheater 370 may be integrated as a component of evaporator 320 or condenser 340, rather than as a separate device.

[0059] A refrigerant bypass valve 332 is provided between the condenser 340 and the reheater 370 to control the flow rate of high-temperature refrigerant liquid from the condenser 340 to the reheater 370. A controller can instruct the operation of the refrigerant bypass valve 332 to control the amount of high-temperature refrigerant liquid passing through the reheater 370 from the condenser 340. For example, the controller can instruct the bypass valve 332 to allow more / less high-temperature refrigerant liquid to pass through the reheater 370, thereby heating the low-temperature refrigerant vapor via the reheater 370. Doing so can increase / decrease the refrigerant suction superheat at the suction port 310a of the compressor 310.

[0060] The heat pump 300 also includes a thermosiphon circuit for performing and controlling heat exchange between at least two of the following: (i) the oil from the oil separator 315 and the refrigerant liquid from the evaporator 320, and (ii) the oil from the oil separator 315 and the refrigerant liquid from the condenser 340. The thermosiphon circuit can provide staged cooling for the oil from the oil separator 315. Figure 3 In the illustrated embodiment, the thermosiphon circuit includes a condenser thermosiphon device 362, which acts as a heat exchanger between the oil from the oil separator 315 and the refrigerant liquid from the condenser 340 to cool the oil from the separator 315. The evaporated refrigerant returns to the condenser 340.

[0061] The thermosiphon circuit also includes an evaporator thermosiphon 364, which serves as a heat exchanger between the oil from the condenser thermosiphon 362 and the refrigerant liquid from the evaporator 320. The refrigerant liquid is guided from the evaporator 320 through the evaporator thermosiphon 364 via a liquid line 356, absorbing heat from the oil from the condenser thermosiphon 362 to further cool the oil. The evaporated refrigerant is guided from the evaporator thermosiphon 364 to the suction port 310a of the compressor 310 via a discharge line 365.

[0062] An oil bypass valve 367 is provided between the condenser thermosiphon 362 and the evaporator thermosiphon 364 to control the oil flow rate from the condenser thermosiphon 362 to the evaporator thermosiphon 364. A controller can control the opening of the oil bypass valve 367 to control the amount of heat exchange between the high-temperature oil and the low-temperature refrigerant liquid through the evaporator thermosiphon 364. For example, the controller can instruct the operation of the bypass valve 367 to allow more / less oil to pass through the evaporator thermosiphon 364, thereby increasing / decreasing the corresponding refrigerant superheat at the outlet of the evaporator thermosiphon 364. In one embodiment, the oil bypass valve 367 allows a portion of the oil from the condenser thermosiphon 362 to pass through the evaporator thermosiphon 364 to maintain the corresponding refrigerant superheat within a desired range (e.g., between about 0°F and about 50°F).

[0063] A control valve 368 is provided at the exhaust line 365 to control the refrigerant flow from the evaporator thermosiphon 364 to the suction port 310a of the compressor 310. A controller can monitor the refrigerant pressure difference between the suction port 310a and the evaporator 350, i.e., the refrigerant pressure drop from the outlet 320a of the evaporator 320 to the suction port 310a of the compressor 310, and adjust the control valve based on this monitoring result. One or more pressure sensors can be provided at the outlet 320a and the suction port 310a to measure the refrigerant pressure. In one embodiment, the control valve 368 can be controlled to coordinate with the operation of the suction regulating valve 350. For example, when the suction regulating valve 350 is partially closed and the refrigerant pressure difference increases, the controller can instruct the control valve 368 to operate to reduce the valve opening to prevent excessive liquid refrigerant from flowing into the compressor 310. The level of valve opening can be determined based on the monitored refrigerant pressure difference.

[0064] The heat pump 300 also includes an optional oil cooler 366 located downstream of the evaporator thermosiphon 364 and bypass valve 367 for actively cooling the oil passing through the oil cooler 366. Cooled refrigerant liquid can be guided under pressure from the oil cooler expansion device 366a, which receives refrigerant liquid from the condenser 340. The cooled oil returns to the compressor 310 via an oil return line 369, where a temperature sensor can be installed to measure the oil temperature. Evaporated refrigerant is guided to the suction port 310a of the compressor 310, where a temperature sensor can be installed to measure the refrigerant temperature. It should be understood that the operation of the oil cooler 366 and / or the oil cooler expansion device 366a is optional and can be activated as needed to further cool the oil.

[0065] In one embodiment, heat pump 300 may include one or more heaters mounted at one or more components of heat pump 300, including, for example, oil separator 315, exhaust chamber of compressor 310, motor chamber of compressor 310, suction line of compressor 310, or suction port 310a of compressor 310. When heat pump 300 is off, a controller may monitor the component temperatures of heat pump 300, such as the motor temperature of compressor 310. When the motor temperature is below a predetermined threshold (e.g., 60°C to 80°C), the controller may instruct one or more heaters to heat the relevant components to prevent refrigerant migration and condensation in compressor 310 and oil separator 315. When heat pump 300 is off, the heaters may also heat one or more suction lines (e.g., suction line 352) and / or other refrigerant loop components (e.g., reheater 370). Heated suction lines (one or more) and / or other refrigerant circuit components can heat the refrigerant fluid (e.g., vapor) during startup to increase suction / discharge superheat to the desired range in a shortened time and prevent refrigerant from flooding compressor 310 and oil separator 315.

[0066] Figure 4 According to one embodiment, it is used to control a heat pump (e.g.) Figure 3 Flowchart 400 of the method for heat pump 300.

[0067] Flowchart 400 may include one or more operations, actions, or functions depicted by one or more modules 410, 415, 420, 430, 435, and 440. Although the modules shown are discrete, they may be divided into additional modules, combined into fewer modules, or eliminated, depending on the desired implementation. In one embodiment, method 400 may be... Figure 2 The control system 130 or any other suitable control system or controller shall be used for execution.

[0068] Flowchart 400 may begin at module 410. At module 410 (Detecting Start-up or Transition Phase), the control system or controller detects whether the heating, ventilation, air conditioning, and cooling (HVACR) system has started operation or is in a transition phase (e.g., changing from a first mode to a second mode). For example, the control system or controller detects… Figure 3 Whether the heat pump 300 is in the startup phase, normal operation phase, or during the transition from the first operating mode to the second operating mode. Method 400 can continue to module 415.

[0069] At module 415 (Activate Intake Regulating Valve), when the system starts operating or is in a transition phase (e.g., changing operating mode), the control system or controller sends a command to activate the intake regulating valve. For example, when the system starts operating, intake regulating valve 350 can be activated to change from a fully open state to a partially closed state. Method 400 can continue to module 420.

[0070] At module 420 (monitoring at least one of (i) pressure differential and (ii) superheat), the control system or controller receives sensing data from various sensors 182 in the HVACR system to monitor at least one of: (i) the refrigerant pressure differential at the expansion unit 330 and (ii) the refrigerant superheat downstream of the suction regulating valve 350. For example, the control system or controller may receive pressure data from pressure sensors at one or more monitoring points to monitor refrigerant pressure at the condenser 340 and evaporator 320, thereby determining the pressure differential downstream / upstream of the expansion unit 330; receive temperature data from a temperature sensor at the suction port 310a of the compressor 310 to monitor refrigerant temperature, thereby determining suction superheat; and / or receive temperature data from a temperature sensor at the discharge line 313 of the compressor 310 to monitor refrigerant temperature, thereby determining discharge superheat. It should be understood that, in one embodiment, the ultimate goal of the suction regulating valve 350 is to control the refrigerant pressure differential at the expansion unit and the discharge superheat at the compressor outlet within their respective desired ranges. Maintaining the exhaust superheat within the desired range can improve compressor reliability. Method 400 can continue to module 430.

[0071] In one embodiment, the refrigerant pressure difference downstream / upstream of the expansion device 330 can be determined by measuring the refrigerant pressure at the condenser 340 and the refrigerant pressure at the evaporator 320. This expansion device pressure difference is the refrigerant pressure difference between the condenser 340 and the evaporator 320. The condenser 340 and the evaporator 320 may each include a pressure sensor to measure their respective refrigerant pressure. In one embodiment, the refrigerant pressure difference downstream / upstream of the expansion device 330 can be determined by measuring a first refrigerant pressure at a first point downstream of the expansion device 330 and a second refrigerant pressure at a second point upstream of the expansion device 330. The first point may be located, for example, at the outlet of the expansion device 330. The second point may be located, for example, at the inlet of the expansion device 330. It should be understood that the first and second measuring points can be anywhere in the refrigeration system except for the portion between the suction regulating valve 350 and the compressor 310.

[0072] In one embodiment, the refrigerant superheat downstream of the suction regulating valve 350 can be determined based on the refrigerant vapor temperature measured at the discharge line 313 of the compressor 310. The difference between this measured temperature and the refrigerant saturation temperature at the corresponding discharge pressure can be determined as the measured discharge superheat. In another embodiment, the refrigerant superheat downstream of the suction regulating valve 350 can be determined based on the refrigerant vapor temperature measured at the suction line 352 of the compressor 310. The difference between this measured temperature and the refrigerant saturation temperature at the corresponding suction pressure can be determined as the measured suction superheat. The suction pressure can be measured by a pressure sensor located at or near the suction port 310a of the compressor 310.

[0073] In module 430 (Pressure / Superheat), the control system or controller determines whether (i) the refrigerant pressure difference downstream / upstream of expansion unit 330 is at or below a predetermined pressure level, and / or (ii) the refrigerant discharge superheat is at or below a predicted refrigerant superheat level. When the control system or controller determines that (i) the refrigerant pressure difference downstream / upstream of expansion unit 330 (e.g., between condenser 340 and evaporator 320) is at or below a predetermined pressure level, or (ii) the refrigerant discharge superheat is at or below a predicted refrigerant superheat level, method 400 proceeds to module 435. When the control system or controller determines that (i) the pressure difference downstream / upstream of expansion unit 330 is above a predetermined pressure level, and (ii) the refrigerant discharge superheat is above a predicted refrigerant superheat level, method 400 may proceed to module 440.

[0074] It should be understood that refrigerant discharge superheat and refrigerant suction superheat can be correlated. In one embodiment, suction superheat can be changed by controlling suction regulating valve 350, and discharge superheat can be changed accordingly. In another embodiment, the control system or controller can directly monitor discharge superheat instead of suction superheat.

[0075] At module 435 (holding valve state), the control system or controller sends a command to the suction regulating valve 350 to maintain its partially closed state. In one embodiment, the partially closed state can be maintained when at least one of the pressure differential and the refrigerant discharge superheat does not increase to the corresponding threshold level (e.g., a predetermined pressure level and a predicted refrigerant superheat level). Method 400 can continue to module 420.

[0076] In module 440 (regulating valve state), the control system or controller sends a command to the suction regulating valve 350 to open it from a partially closed state, thereby increasing the refrigerant flow from the outlet 320a of the evaporator 320 to the suction port 310a of the compressor 310. In one embodiment, the suction regulating valve 350 may open from its partially closed state when both the pressure differential and the refrigerant discharge superheat increase to a corresponding threshold level or higher (e.g., about 5 psi above a predetermined pressure level and about 3°F above a predicted refrigerant superheat level). Method 400 may continue to module 420.

[0077] In one embodiment, the control system or controller may instruct the suction regulating valve 350 to wait for a period of time before opening from its partially closed state until both the pressure differential and the refrigerant discharge superheat increase to a range above a corresponding threshold level. This is known as the "dead zone," which refers to the range or band of values ​​within which no regulation occurs. For example, the control system or controller may instruct the suction regulating valve 350 to wait and remain partially closed until the monitored pressure differential is above a certain range, such as 5 psi above a predetermined pressure level. It should be understood that the range of the dead zone can be dynamically determined. For example, the control system or controller may compare the real-time measured refrigerant discharge superheat with a predetermined / preset refrigerant superheat level and calculate the integral of the difference between the measured value and the predetermined / preset level over time. The control system or controller may instruct the suction regulating valve 350 to wait and remain partially closed until the integral result is greater than the preset level. The dead zone or threshold level of the refrigerant superheat can be predicted or simulated by any suitable mathematical equation or method.

[0078] It should be understood that the opening of the suction regulating valve 350 can be continuously adjusted based on the pressure difference downstream / upstream of the monitored expansion device 330 and / or the refrigerant superheat downstream of the suction regulating valve 350 (e.g., refrigerant exhaust superheat).

[0079] In one embodiment, the control system or controller may determine a first opening of the suction regulating valve 350 based on the monitored pressure difference downstream / upstream of the expansion device 330 (e.g., the refrigerant pressure difference between the condenser 340 and the evaporator 320), and a second opening of the suction regulating valve 350 based on the monitored refrigerant superheat downstream of the suction regulating valve 350 (e.g., refrigerant discharge superheat). The control system or controller may instruct the suction regulating valve 350 to open at the smaller of the first and second openings to ensure the operational stability and reliability of the system. For example, when the control system or controller determines to fully open the suction regulating valve 350 based on the monitored pressure difference and to partially close the suction regulating valve 350 based on the monitored refrigerant superheat, the final decision made by the control system or controller may be to partially close the suction regulating valve 350.

[0080] Figure 5 This is a flowchart 500 of a method for controlling a heat pump during a startup phase or a mode change phase, according to one embodiment.

[0081] Flowchart 500 may include one or more operations, actions, or functions depicted by one or more modules 510, 520, 530, 535, 540, and 550. Although the modules shown are discrete, they may be divided into additional modules, combined into fewer modules, or eliminated, depending on the desired implementation. In one embodiment, method 500 may be... Figure 2 The control system 130 or any other suitable control system or controller shall be used for execution.

[0082] Flowchart 500 can begin at module 510. At module 510 (Standby Detection), the control system or controller detects whether the heating, ventilation, air conditioning, and cooling (HVACR) system is in standby mode, awaiting a start command or a command to change from a first mode to a second mode. For example, the control system or controller detects… Figure 3 Is the heat pump 300 in standby mode, i.e., the system is running but not actively participating in its main functions, and can be put into use when needed? Method 500 can continue to module 520.

[0083] At module 520 (determining refrigerant saturation pressure difference), the control system or controller determines the refrigerant saturation pressure difference at the respective temperatures of the condenser 340 and the evaporator 320. In one embodiment, the control system or controller may monitor a first temperature of the process fluid (e.g., water) at the condenser 340 and a second temperature of the process fluid (e.g., water) at the evaporator 320, respectively. The corresponding saturation pressures of the refrigerant at the first and second temperatures of the respective process fluids at the condenser 340 and the evaporator 320, and the associated refrigerant saturation pressure differences, can be determined. Method 500 may continue to module 530.

[0084] At module 530 (lower?), the control system or controller compares the refrigerant saturation pressure difference with a predetermined pressure level, which can be compared with... Figure 4 The predetermined pressure level at module 430 may be the same as or different from the predetermined pressure level. When the refrigerant saturation pressure difference is equal to or lower than the predetermined pressure level, method 500 may continue to module 540. When the refrigerant saturation pressure difference is greater than the predetermined level, method 500 may continue to module 535.

[0085] At module 535 (fully open suction regulating valve), when the refrigerant saturation pressure difference is greater than a predetermined level, the control system or controller sends a command to activate suction regulating valve 350 to the fully open state.

[0086] At module 540 (Detecting Startup or Transition Phase), the control system or controller detects whether the system has started operating or is in a transition phase (e.g., changing from a first mode to a second mode). For example, the control system or controller detects... Figure 3 Whether the heat pump 300 is in the startup phase, normal operation phase, or during the transition from the first operating mode to the second operating mode. Method 500 can continue to module 550.

[0087] At module 550 (partially closing the intake regulating valve when the system starts), when the system starts operating or is in a transition phase (e.g., changing operating mode), the control system or controller sends a command to activate the intake regulating valve 350. For example, when the system starts operating, the intake regulating valve 350 can be activated to change from a fully open state to a partially closed state.

[0088] Figure 6 This is a flowchart of a method for controlling a reheater of a heat pump according to one embodiment.

[0089] Flowchart 600 may include one or more operations, actions, or functions depicted by one or more modules 605, 610, 620, 630, 635, and 640. Although the modules shown are discrete, they may be divided into additional modules, combined into fewer modules, or eliminated, depending on the desired implementation. In one embodiment, method 600 may be... Figure 2 The control system 130 or any other suitable control system or controller shall be used for execution.

[0090] Flowchart 600 may begin at module 605. At module 605 (Determining System Operating Status), the control system or controller detects the operating status of the heating, ventilation, air conditioning, and refrigeration (HVACR) system. For example, the control system or controller detects this by receiving an indication that the intake regulating valve is fully open. Figure 3 The heat pump 300 is in a stable operating phase. It should be understood that the system can be detected as being in any operating period / phase, including, for example, the start-up phase, the stable operating phase, or the transition phase. During the stable operating phase, it may be relatively easier for the reheater to control the refrigerant suction superheat. Method 600 can continue to module 610.

[0091] At module 610 (reheating refrigerant vapor), the control system or controller instructs the system to direct the relatively high-temperature refrigerant liquid from condenser 340 and the relatively low-temperature refrigerant vapor from evaporator 350 to reheater 370 for heat exchange. The reheated refrigerant vapor is then directed to suction port 310a of compressor 310. Method 600 can continue to module 615.

[0092] At module 620 (measuring suction superheat), the control system or controller receives sensor data to measure refrigerant superheat. In one embodiment, the refrigerant superheat downstream of suction regulating valve 350 (e.g., refrigerant suction superheat) can be determined based on the refrigerant vapor temperature measured at suction line 352 of compressor 310. The difference between this measured temperature and the refrigerant saturation temperature at the corresponding suction pressure can be determined as the measured suction superheat. Method 600 can continue to module 620.

[0093] At module 630 (Below Target?), the control system or controller determines whether the measured refrigerant suction superheat is below a predetermined / predefined / preset / target refrigerant suction superheat level (i.e., the suction superheat target). In one embodiment, the superheat target may be determined based on operating parameters of the system in a stable operating state. When the measured refrigerant suction superheat is greater than the superheat target, method 600 may proceed to module 635. When the measured refrigerant suction superheat is equal to or below the superheat target, method 600 may proceed to module 640.

[0094] At module 635 (open refrigerant bypass valve), when the measured refrigerant suction superheat exceeds the superheat target, the control system or controller sends a command to open the refrigerant bypass valve to reduce the amount of refrigerant flowing from the condenser through the reheater 370. Method 600 can continue to module 620.

[0095] At module 640 (refrigerant bypass valve closed), when the measured refrigerant suction superheat is equal to or below the superheat target, the control system or controller sends a command to close the refrigerant bypass valve to increase the amount of refrigerant flowing from the condenser through the reheater 370. Method 600 can continue to module 620.

[0096] Figure 7 This is a flowchart 700 of a method for controlling oil cooling and refrigerant superheat in a heat pump according to one embodiment.

[0097] Flowchart 700 may include one or more operations, actions, or functions depicted by one or more modules 705, 710, 720, 730, 740, 745, and 750. Although the modules shown in the figure are discrete, the various modules may be divided into additional modules, combined into fewer modules, or eliminated, depending on the desired implementation. In one embodiment, method 700 may be... Figure 2 The control system 130 or any other suitable control system or controller shall be used for execution.

[0098] Flowchart 700 may begin at module 705. At module 705 (cooling oil from the oil separator via a first thermosiphon), the control system or controller instructs the system to direct hot oil from the oil separator and liquid refrigerant from condenser 340 to condenser thermosiphon 362 for heat exchange to cool the oil. Method 700 may continue to module 710.

[0099] At module 710 (cooling oil from the first thermosiphon via the second thermosiphon), the control system or controller instructs the system to direct oil from the condenser thermosiphon 362 and refrigerant liquid from the evaporator 320 to the evaporator thermosiphon 364 for heat exchange to further cool the oil. Method 700 can continue to module 720.

[0100] At module 720 (regulating oil bypass valve), the control system or controller sends a command to activate oil bypass valve 367, thereby controlling the amount of oil flowing from condenser thermosiphon 362 through evaporator thermosiphon 364. The controller can instruct the operation of bypass valve 367 to allow more / less oil to flow through evaporator thermosiphon 364 to heat the refrigerant liquid from liquid line 356 and increase / decrease the corresponding refrigerant superheat at the outlet of evaporator thermosiphon 364. In one embodiment, bypass valve 367 can control the oil quantity at a certain level to keep the corresponding refrigerant superheat within the range required for stable system operation. In one embodiment, Figure 3 An optional oil cooler 366 can be positioned downstream of the evaporator thermosiphon 364 and bypass valve 367 to provide active cooling for the oil passing through the oil cooler 366. Method 700 can continue to module 730.

[0101] At module 730 (monitoring the state of the intake regulating valve), the control system or controller monitors the state of the intake regulating valve 350. For example, the control system or controller may receive sensor data or signals from the intake regulating valve 350 to determine whether the intake regulating valve 350 is fully open or partially closed. Method 700 may continue to module 740.

[0102] At module 740 (Partially Closed?), the control system or controller determines whether the intake regulating valve 350 is partially closed or fully open. When the control system or controller determines that the intake regulating valve 350 is fully open, method 700 can proceed to module 745. When the control system or controller determines that the intake regulating valve 350 is partially closed, method 700 can proceed to module 750.

[0103] At module 745 (open control valve), when the control system or controller determines that the intake regulating valve 350 is fully open, the control system or controller sends a command to control valve 368 to fully open control valve 368.

[0104] At module 750 (close control valve), when the control system or controller determines that the suction regulating valve 350 is partially closed, the control system or controller sends a command to at least partially close control valve 368 to reduce refrigerant flow and prevent excessive refrigerant liquid from flowing from the evaporator thermosiphon 364 to the suction port 310a of the compressor 310. In one embodiment, the controller may monitor the refrigerant pressure drop caused by the suction regulating valve 350 and adjust control valve 368 based on the monitored refrigerant pressure drop. While not wishing to be bound by theory, it is believed that partially closing the suction regulating valve may introduce a pressure drop that could induce an undesirable large amount of refrigerant liquid to flow from the liquid line 356 into the evaporator thermosiphon 364, which could have undesirable effects on the compressor 310. The control system or controller may coordinate the operation of suction regulating valve 350 and control valve 368 to prevent such problems.

[0105] aspect: It should be understood that any of aspects 1-10 can be combined with any of aspects 11-20.

[0106] Aspect 1. A heating, ventilation, air conditioning and cooling (HVACR) system, comprising: A refrigerant circuit, comprising an evaporator, a compressor, an expansion unit, and a condenser, for operating a refrigerant therein; A suction regulating valve that connects the outlet fluid of the evaporator to the suction port of the compressor, the suction regulating valve being configured to control the refrigerant flow rate from the outlet of the evaporator to the suction port of the compressor; and The controller is configured to: Monitor at least one of the following: (i) the refrigerant pressure differential at the expansion device; and (ii) the refrigerant superheat downstream of the suction regulating valve; and The suction regulating valve is adjusted based on the monitoring results to control the refrigerant pressure drop from the outlet of the evaporator to the suction port of the compressor.

[0107] Aspect 2. According to the system described in aspect 1, the controller is further configured to: Before the compressor starts operating, determine the refrigerant saturation pressure difference at the respective temperatures of the condenser and the evaporator; and When the compressor starts working, the suction regulating valve is adjusted according to the refrigerant saturation pressure difference.

[0108] Aspect 3. According to the system described in aspect 1 or 2, the controller is further configured to: Monitor the refrigerant pressure difference upstream and downstream of the expansion device; and When the compressor starts working, the suction regulating valve is activated to a partially closed state at an opening degree according to the refrigerant pressure difference.

[0109] Aspect 4. In the system according to any one of aspects 1-3, the controller is further configured to: Monitor the change in the refrigerant pressure difference at the expansion device; and The intake regulating valve is activated to open according to the change in the refrigerant pressure difference.

[0110] Aspect 5. The system according to any one of aspects 1-4, wherein the controller is further configured to: The refrigerant superheat downstream of the suction regulating valve is compared with a predetermined refrigerant superheat level; and Based on the results of the comparison, the intake regulating valve is activated to open at a certain degree.

[0111] Aspect 6. The system according to any one of aspects 1-5 further includes a reheater configured to perform heat exchange between refrigerant liquid from the condenser and refrigerant vapor from the evaporator to heat the refrigerant vapor.

[0112] Aspect 7. The system according to aspect 6 further includes a refrigerant bypass valve for controlling the refrigerant liquid flow rate from the condenser to the reheater.

[0113] Aspect 8. The system according to any one of aspects 1-7 further includes a thermosiphon circuit for heat exchange between refrigerant liquid from the evaporator and oil from the compressor to evaporate the refrigerant liquid into refrigerant vapor.

[0114] Aspect 9. According to the system of aspect 8, the thermosiphon circuit includes a control valve for controlling the flow rate of the refrigerant vapor to the suction port of the compressor.

[0115] Aspect 10. The system according to aspect 8 or 9 further includes an oil bypass valve for controlling the flow rate of the oil flowing into the thermosiphon circuit.

[0116] Aspect 11. A method for controlling a heating, ventilation, air conditioning, and refrigeration (HVACR) system, the system including a refrigerant circuit, the refrigerant circuit including an evaporator, a compressor, an expander, and a condenser for operating a refrigerant therein; the method comprising: The outlet fluid of the evaporator is connected to the suction port of the compressor via a suction regulating valve, which is configured to control the refrigerant flow from the evaporator to the suction port of the compressor. Monitor at least one of the following: (i) the refrigerant pressure differential at the expansion device; and (ii) the refrigerant superheat downstream of the suction regulating valve; and The suction regulating valve is adjusted based on the monitoring results to control the refrigerant pressure drop from the outlet of the evaporator to the suction port of the compressor.

[0117] Aspect 12. The method according to aspect 11 further includes: Monitor the temperature of the condenser and the evaporator; Before the compressor starts operating, determine the refrigerant saturation pressure difference at the temperatures of the condenser and the evaporator; and When the compressor starts working, the suction regulating valve is adjusted to a certain opening degree according to the refrigerant saturation pressure difference.

[0118] Aspect 13. The method described in aspect 12 further includes:

[0119] When the refrigerant saturation pressure difference is lower than a predetermined value, the suction regulating valve is activated to a partially closed state; and When the refrigerant saturation pressure difference is greater than the predetermined value, the suction regulating valve is activated to the fully open state.

[0120] Aspect 14. The method described according to any one of aspects 11-13 further includes: When the compressor starts working, monitor the refrigerant pressure difference at the expansion device; and The intake regulating valve is activated to open at a certain opening degree based on the pressure difference of the agent.

[0121] Aspect 15. The method according to any one of aspects 11-14 further includes: Monitor the change in pressure difference of the expansion device; and The intake regulating valve is activated to open by a certain degree based on the change in the pressure difference.

[0122] Aspect 16. The method according to any one of aspects 11-15 further includes: The refrigerant superheat downstream of the suction regulating valve is compared with a predetermined refrigerant superheat level; and Based on the results of the comparison, the intake regulating valve is activated to open at a certain degree.

[0123] Aspect 17. The method according to any one of aspects 11-16 further includes heat exchange between a controlled amount of refrigerant from the condenser and refrigerant from the evaporator via a reheater.

[0124] Aspect 18. The method according to any one of aspects 11-17 further includes heat exchange between a controlled amount of oil from the compressor and refrigerant liquid from the evaporator via a thermosiphon circuit to evaporate the liquid refrigerant into refrigerant vapor.

[0125] Aspect 19. The method according to aspect 18 further includes controlling the flow rate of the refrigerant vapor to the suction port of the compressor via a control valve.

[0126] Aspect 20, the method according to aspect 19, further includes at least partially closing the control valve when the intake regulating valve is detected to be in a partially closed state.

[0127] The terminology used in this specification is intended to describe particular embodiments and is not intended to be limiting. Unless otherwise expressly stated, the terms "a," "an," and "the" also include the plural forms. When the terms "comprising" and / or "including" are used in this specification, the presence of the stated features, integers, steps, operations, elements, and / or components is specified, but the presence or addition of one or more other features, integers, steps, operations, elements, and / or components is not excluded.

[0128] Regarding the foregoing description, it should be understood that detailed changes can be made, particularly in terms of the building materials used and the shape, size, and arrangement of components, without departing from the scope of this disclosure. This specification and the described embodiments are merely exemplary, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A heating, ventilation, air conditioning and refrigeration (HVACR) system, characterized in that, include: A refrigerant circuit, comprising an evaporator, a compressor, an expansion unit, and a condenser, for operating a refrigerant therein; A suction regulating valve that connects the outlet fluid of the evaporator to the suction port of the compressor, the suction regulating valve being configured to control the refrigerant flow from the outlet of the evaporator to the suction port of the compressor; as well as The controller is configured to: Monitor at least one of the following: (i) the refrigerant pressure differential at the expansion device; and (ii) the refrigerant superheat downstream of the suction regulating valve; and The suction regulating valve is adjusted based on the monitoring results to control the refrigerant pressure drop from the outlet of the evaporator to the suction port of the compressor.

2. The system according to claim 1, characterized in that, The controller is also configured to: Before the compressor starts operating, determine the refrigerant saturation pressure difference at the respective temperatures of the condenser and the evaporator; and When the compressor starts working, the suction regulating valve is adjusted according to the refrigerant saturation pressure difference.

3. The system according to claim 1, characterized in that, The controller is also configured to: Monitor the refrigerant pressure difference upstream and downstream of the expansion device; and When the compressor starts working, the suction regulating valve is activated to a partially closed state at an opening degree according to the refrigerant pressure difference.

4. The system according to claim 1, characterized in that, The controller is also configured to: Monitor the change in the refrigerant pressure difference at the expansion device; and The intake regulating valve is activated to open according to the change in the refrigerant pressure difference.

5. The system according to claim 1, characterized in that, The controller is also configured to: The refrigerant superheat downstream of the suction regulating valve is compared with a predetermined refrigerant superheat level; and Based on the results of the comparison, the intake regulating valve is activated to open at a certain degree.

6. The system according to claim 1, characterized in that, It also includes a reheater configured to exchange heat between refrigerant liquid from the condenser and refrigerant vapor from the evaporator to heat the refrigerant vapor.

7. The system according to claim 6, characterized in that, It also includes a refrigerant bypass valve for controlling the refrigerant liquid flow rate from the condenser to the reheater.

8. The system according to claim 1, characterized in that, It also includes a thermosiphon circuit for heat exchange between refrigerant liquid from the evaporator and oil from the compressor to evaporate the refrigerant liquid into refrigerant vapor.

9. The system according to claim 8, characterized in that, The thermosiphon circuit includes a control valve for controlling the flow rate of the refrigerant vapor to the suction port of the compressor.

10. The system according to claim 8, characterized in that, The thermosiphon circuit also includes an oil bypass valve for controlling the flow rate of the oil flowing into the thermosiphon circuit.

11. A method for controlling a heating, ventilation, air conditioning, and refrigeration (HVACR) system, characterized in that, The system includes a refrigerant circuit, the refrigerant circuit including an evaporator, a compressor, an expander, and a condenser, for operating a refrigerant therein; the method includes: The outlet fluid of the evaporator is connected to the suction port of the compressor via a suction regulating valve, which is configured to control the refrigerant flow from the evaporator to the suction port of the compressor. Monitor at least one of the following: (i) the refrigerant pressure differential at the expansion device; and (ii) the refrigerant superheat downstream of the suction regulating valve; and The suction regulating valve is adjusted based on the monitoring results to control the refrigerant pressure drop from the outlet of the evaporator to the suction port of the compressor.

12. The method according to claim 11, characterized in that, Also includes: Monitor the temperature of the condenser and the evaporator; Before the compressor starts operating, determine the refrigerant saturation pressure difference at the temperature of the condenser and the evaporator; as well as When the compressor starts working, the suction regulating valve is adjusted to a certain opening degree according to the refrigerant saturation pressure difference.

13. The method according to claim 12, characterized in that, Also includes: When the refrigerant saturation pressure difference is lower than a predetermined value, the suction regulating valve is activated to a partially closed state; and When the refrigerant saturation pressure difference is greater than the predetermined value, the suction regulating valve is activated to the fully open state.

14. The method according to claim 11, characterized in that, Also includes: When the compressor starts working, monitor the refrigerant pressure difference at the expansion device; as well as The intake regulating valve is activated to open at a certain opening degree based on the pressure difference of the agent.

15. The method according to claim 11, characterized in that, Also includes: Monitor the change in the pressure difference of the expansion device; as well as The intake regulating valve is activated to open by a certain degree based on the change in the pressure difference.

16. The method according to claim 11, characterized in that, Also includes: The refrigerant superheat downstream of the intake regulating valve is compared with a predetermined refrigerant superheat level; as well as Based on the results of the comparison, the intake regulating valve is activated to open at a certain degree.

17. The method according to claim 11, characterized in that, It also includes heat exchange between a controlled amount of refrigerant from the condenser and refrigerant from the evaporator via a reheater.

18. The method according to claim 11, characterized in that, It also includes heat exchange between a controlled amount of oil from the compressor and liquid refrigerant from the evaporator via a thermosiphon circuit to evaporate the liquid refrigerant into refrigerant vapor.

19. The method according to claim 18, characterized in that, It also includes controlling the flow rate of the refrigerant vapor to the suction port of the compressor via a control valve.

20. The method according to claim 19, characterized in that, It also includes at least partially closing the control valve when the intake regulating valve is detected to be in a partially closed state.

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