Low temperature heat pump system and control method thereof

Abstract

The application relates to the technical field of low-temperature heat pump systems, in particular to a low-temperature heat pump system and a control method thereof. The structure of the low-temperature heat pump system comprises a compressor, a sensible heat circulation device installed on the compressor, the sensible heat circulation device being capable of exchanging heat with the compressor, an evaporator connected with the compressor, a water side heat exchanger connected with the compressor and the evaporator, a main water circuit connected with the water side heat exchanger, and a branch water circuit connected with the main water circuit, the branch water circuit being connected with the sensible heat circulation device, and water flow in the branch water circuit circulating through the sensible heat circulation device. The low-temperature heat pump system and the control method thereof can solve the problems of long heating time and high energy consumption of an electric heating belt used in an existing low-temperature heat pump system.

Description

Technical Field

[0001] This application relates to the field of low-temperature heat pump system technology, and in particular to a low-temperature heat pump system and its control method. Background Technology

[0002] Currently, low-temperature heat pump systems are being used more and more widely, both domestically and internationally, with an increasing adoption rate. The composition of a low-temperature heat pump unit is quite similar to that of a conventional refrigeration system, mainly consisting of four parts: a compressor, condenser, throttling device, and evaporator, along with a matching controller. Considering that the main operating area of ​​low-temperature heat pumps is the low-temperature and ultra-low-temperature environment in northern regions, to prevent water pipes from freezing, manufacturers require that the system's water circuit maintain normal circulation when the unit is shut down, or that the water in the pipes be drained and refilled when heating demand arises. This characteristic dictates that the water in the system's water circuit must be kept in a liquid state, i.e., the water temperature must be above 4℃.

[0003] When a low-temperature heat pump unit is left stagnant for an extended period under low ambient temperature conditions, the temperature at various points on the compressor approaches ambient temperature. This inevitably leads to refrigerant migration, causing liquid refrigerant to accumulate inside the compressor. The longer the stagnant time, the more liquid refrigerant accumulates. If the unit is started under these conditions, the compressor will start with liquid refrigerant. Since liquid refrigerant cannot be compressed, the scroll plate requires significantly more torque to forcefully compress the liquid, resulting in a surge in motor starting current and causing motor overload. Simultaneously, the instantaneous movement of the scroll plate generates a tremendous impact force, which can, in severe cases, cause the scroll plate to shatter. Furthermore, because the compressor's refrigerant oil is diluted by the refrigerant, it cannot form an effective lubricating oil film to protect the compressor. This can cause wear and tear on mechanical components such as the scroll plate and bearings, ultimately damaging the compressor.

[0004] To protect the compressor, the mainstream industry practice is to install an electric heating element near the compressor oil sump. This electric heating causes the refrigerant inside the compressor to evaporate into gas and be discharged, reducing the amount of liquid carried over and preventing the compressor from starting with liquid. However, because the amount of refrigerant migration varies under different ambient temperatures or different resting times, it is often difficult to precisely control the size of the electric heating element and the timing of its activation. Compressor manufacturers generally require that the electric heating element be turned on 8-12 hours before the unit is started, but considering energy consumption, user operation, and user experience, this requirement is often difficult to achieve in practical applications. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a low-temperature heat pump system and its control method to solve the problems of long heating time and high energy consumption of electric heating belts used in existing low-temperature heat pump systems.

[0006] According to a first aspect of the present invention, a low-temperature heat pump system is provided, wherein the low-temperature heat pump system comprises: a compressor; a sensible heat circulation device installed on the compressor, the sensible heat circulation device being capable of exchanging heat with the compressor; an evaporator connected to the compressor; a water-side heat exchanger connected to the compressor and the evaporator; a main water circuit connected to the water-side heat exchanger; and a branch water circuit connected to the main water circuit, the branch water circuit being connected to the sensible heat circulation device, and water flowing in the branch water circuit passing through the sensible heat circulation device.

[0007] Preferably, the main water circuit includes an inlet main circuit and an outlet main circuit, the inlet main circuit being connected to the inlet of the water-side heat exchanger, and the outlet main circuit being connected to the outlet of the water-side heat exchanger; the branch water circuit includes an inlet branch circuit and an outlet branch circuit, the inlet branch circuit being connected to the inlet main circuit, and the outlet branch circuit being connected to the outlet main circuit.

[0008] Preferably, the water circuit branch circuit further includes: a water pump, disposed in the inlet branch circuit or the outlet branch circuit, the water pump being used to provide power for the water circulation in the water circuit branch circuit; and an electric valve, disposed in the inlet branch circuit or the outlet branch circuit, the electric valve being used to control the on / off state of the water circuit branch circuit.

[0009] Preferably, the sensible heat circulation device is formed in a strip shape and is arranged circumferentially around the outer periphery of the compressor. The two ends of the sensible heat circulation device are respectively provided with a water inlet and a water outlet. The water inlet branch is connected to the water inlet, and the water outlet branch is connected to the water outlet.

[0010] Preferably, the sensible heat circulation device is arranged around the lower end of the compressor casing, or the sensible heat circulation device is arranged around the outer periphery of the compressor's lower cover. A temperature sensor is provided on the compressor casing, and the compressor can start when the temperature detected by the temperature sensor is higher than a preset temperature.

[0011] Preferably, the inner surface of the sensible heat circulation device is attached to the outer surface of the compressor, and the inner surface of the sensible heat circulation device is made of a thermally conductive material.

[0012] Preferably, the low-temperature heat pump system further includes: a throttling device disposed between the water-side heat exchanger and the evaporator, the throttling device being connected to the water-side heat exchanger and the evaporator via a pipeline; and a fan disposed on the side of the evaporator for blowing air onto the evaporator.

[0013] According to a second aspect of the present invention, a control method for a low-temperature heat pump system is provided, wherein the low-temperature heat pump system is as described above, and the control method for the low-temperature heat pump system includes: controlling the sensible heat circulation device to exchange heat with the compressor by controlling the opening and closing of the water pump and the electric valve.

[0014] Preferably, before the compressor starts at low temperature, when the main water circuit is in a circulating flow state, the water pump is turned off and the electric valve is turned on; when the main water circuit is in a non-circulating flow state, the water pump is turned on and the electric valve is turned on.

[0015] Preferably, after the compressor starts at low temperature, the water pump is turned off. When the compressor is a low-pressure chamber compressor, the electric valve is opened or closed according to the performance requirements of the low-temperature heat pump system. When the compressor is a high-pressure chamber compressor, the electric valve is closed first, and then opened after the stable exhaust superheat required by the compressor is established.

[0016] The low-temperature heat pump system and its control method of this invention include a sensible heat circulation device installed on the compressor, which can exchange heat with the compressor. A water-side heat exchanger is connected to the compressor and the evaporator. The main water circuit is connected to the water-side heat exchanger to exchange heat with the refrigerant. A branch water circuit is connected to the main water circuit. The sensible heat circulation device is connected to the branch water circuit, allowing the water flow in the branch water circuit to heat the compressor, thereby evaporating the refrigerant inside the compressor and discharging it from the compressor, thus improving the reliability of the compressor during startup. Furthermore, because the sensible heat circulation device has a large heat exchange area and the water is in a flowing state, its heat exchange efficiency is higher than that of an electric heating belt while maintaining the water flow rate, effectively reducing the time and energy consumption required to heat the compressor.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a low-temperature heat pump system according to the present invention.

[0020] Figure 2This is a schematic diagram of the flow direction of the low-temperature heat pump system according to the present invention.

[0021] Figure 3 This is a schematic diagram of the sensible heat circulation device of the low-temperature heat pump system according to the present invention installed on the compressor.

[0022] Figure 4 This is a schematic diagram of the sensible heat circulation device of the low-temperature heat pump system according to the present invention.

[0023] Reference numerals: 1-Compressor; 10-Shell; 11-Lower cover; 13-Temperature sensor; 2-Sensible heat circulation device; 21-Water inlet; 22-Water outlet; 3-Evaporator; 4-Water-side heat exchanger; 41-Water inlet; 42-Water outlet; 5-Main water circuit; 51-Main water inlet; 52-Main water outlet; 6-Branch water circuit; 61-Branch water inlet; 62-Branch water outlet; 63-Water pump; 64-Electric valve; 7-Throttling device; 8-Fan; 100-Refrigerant flow direction; 200-Water flow direction. Detailed Implementation

[0024] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0025] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0026] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0027] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0028] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0029] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0030] The terminology used herein is for the purpose of describing various examples only and is not intended to limit the examples. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0031] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0032] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application.

[0033] like Figures 1 to 4 As shown, according to a first aspect of the present invention, a low-temperature heat pump system is provided, the low-temperature heat pump system comprising a compressor 1, a sensible heat circulation device 2, an evaporator 3, a water-side heat exchanger 4, a main water circuit 5, and a branch water circuit 6.

[0034] In the following description, reference will be made to Figures 1 to 4 The specific structure of the aforementioned components of the low-temperature heat pump system and their connection relationships are described in detail.

[0035] like Figures 1 to 4 As shown, in this embodiment, the sensible heat circulation device 2 can be installed on the compressor 1, and the sensible heat circulation device 2 is used for heat exchange with the compressor 1. The evaporator 3 can be connected to the compressor 1 through a pipeline, allowing the refrigerant to flow between the evaporator 3 and the compressor 1. The water-side heat exchanger 4 can be connected to the compressor 1 and the evaporator 3, allowing the refrigerant to flow to the water-side heat exchanger 4 for heat exchange. The main water circuit 5 can be connected to the water-side heat exchanger 4 to achieve heat exchange between the water flow and the refrigerant. The water branch circuit 6 is connected to the main water circuit 5, and the sensible heat circulation device 2 is connected to the water branch circuit 6, allowing the water flow in the water branch circuit 6 to flow to the sensible heat circulation device 2 to heat the compressor 1, thereby evaporating the refrigerant in the compressor 1 and discharging it from the compressor 1, thus improving the reliability of the compressor 1 during startup. In addition, since the heat exchange area of ​​the sensible heat circulation device 2 is large and the water flow is in a flowing state, the heat exchange efficiency of the sensible heat circulation device 2 is higher than that of the electric heating belt while ensuring the water flow rate, thus effectively reducing the time and energy consumption required to heat the compressor 1.

[0036] Preferred, such as Figure 1 and Figure 2 As shown, in this embodiment, the low-temperature heat pump system may further include a throttling device 7 and a fan 8. The throttling device 7 can be disposed between the water-side heat exchanger 4 and the evaporator 3, and is connected to both via a pipeline. Preferably, the throttling device 7 can be an electronic expansion valve. The throttling device 7 is used to regulate the hydraulic pressure of the refrigerant, which exchanges heat with the outside environment through the evaporator 3. The fan 8 can be disposed on the side of the evaporator 3. Specifically, the fan 8 can be installed on top of the evaporator 3 or near and directly facing the evaporator 3. The fan 8 is used to blow air onto the evaporator 3 to promote heat exchange.

[0037] Preferred, such as Figure 1 and Figure 2 As shown, in this embodiment, the main water circuit 5 may include an inlet main circuit 51 and an outlet main circuit 52. The inlet main circuit 51 is connected to the inlet 41 of the water-side heat exchanger 4, and the outlet main circuit 52 is connected to the outlet 42 of the water-side heat exchanger 4. When refrigerant and water flow simultaneously through the water-side heat exchanger 4, the refrigerant can exchange heat with the water. The branch water circuit 6 may include an inlet branch circuit 61 and an outlet branch circuit 62. The inlet branch circuit 61 is connected to the inlet main circuit 51, allowing a portion of the water in the inlet main circuit 51 to flow to the inlet 41 of the water-side heat exchanger 4, and another portion to flow into the inlet branch circuit 61. The outlet branch circuit 62 is connected to the outlet main circuit 52, allowing the water flowing through the sensible heat circulation device 2 to be discharged into the outlet main circuit 52 via the outlet branch circuit 62.

[0038] Furthermore, preferably, the water circuit branch 6 may also include a water pump 63 and an electric valve 64. The water pump 63 may be a miniature water pump 63. The water pump 63 may be installed in the inlet branch 61 or the outlet branch 62. Specifically, as shown... Figure 1 As shown, in this embodiment, a water pump 63 is installed in the inlet branch 61, and the water pump 63 is used to provide power for the water circulation in the water branch circuit 6. An electric valve 64 can be installed in either the inlet branch 61 or the outlet branch 62. Specifically, as... Figure 1 As shown, in this embodiment, an electric valve 64 is installed in the water outlet branch 62. The electric valve 64 is used to control the opening and closing of the water branch circuit 6, thereby controlling the heat exchange between the sensible heat circulation device 2 and the compressor 1.

[0039] Preferred, such as Figure 3 and Figure 4As shown, in this embodiment, the sensible heat circulation device 2 can be formed in a strip shape. A cavity for water flow can be formed within the sensible heat circulation device 2, through which water from the water branch loop 6 flows. The sensible heat circulation device 2 can be circumferentially arranged around the outer periphery of the compressor 1 to exchange heat with the casing 10 of the compressor 1. A water inlet 21 and a water outlet 22 can be respectively provided at both ends of the sensible heat circulation device 2. The water inlet branch 61 can be connected to the water inlet 21, and the water outlet branch 62 can be connected to the water outlet 22, so that the water in the water branch loop 6 can flow through the sensible heat circulation device 2 during circulation and exchange heat with the compressor 1 through the sensible heat circulation device 2.

[0040] Furthermore, preferably, such as Figure 3 As shown, in this embodiment, the sensible heat circulation device 2 can be arranged around the lower end of the casing 10 of the compressor 1 to exchange heat with the casing 10 of the compressor 1. Alternatively, the sensible heat circulation device 2 can also be arranged around the outer periphery of the lower cover 11 of the compressor 1. In this case, it is necessary to ensure that the lower cover 11 of the compressor 1 has sufficient axial length to prevent the sensible heat circulation device 2 from failing to fully conform to the outer wall of the lower cover 11.

[0041] Further optimized, such as Figure 3 As shown, in this embodiment, the inner surface of the sensible heat circulation device 2 can be attached to the outer surface of the compressor 1 to facilitate heat exchange between the sensible heat circulation device 2 and the casing 10 of the compressor 1. The inner surface of the sensible heat circulation device 2 can be made of a thermally conductive material. Specifically, the inner surface of the sensible heat circulation device 2 can be made of a metal material with good thermal conductivity, such as aluminum.

[0042] Furthermore, preferably, a temperature sensor 13 may be provided on the casing 10 of the compressor 1. Specifically, a sleeve may be welded to the outer wall of the casing 10 of the compressor 1, and the temperature sensor 13 may be installed inside the sleeve to measure the temperature of the casing 10. When the temperature sensor 13 detects that the temperature of the casing 10 is higher than a preset temperature (the preset temperature may be 0°C), the compressor 1 can start. This configuration can greatly reduce the amount of refrigerant in the compressor 1 when starting at low temperatures (ambient temperature below -15°C), reduce the risk of liquid slugging during low-temperature startup, and thus improve the reliability of the compressor 1 during low-temperature startup.

[0043] During use, such as Figure 2As shown, when compressor 1 starts at low temperature, the refrigerant flow direction 100 can be from compressor 1 to the water-side heat exchanger 4 for heat exchange with the main water circuit 5, then to the throttling device 7 for pressure reduction, then to the evaporator 3 for heat exchange with the outside, and finally back to compressor 1. The water flow direction 200 can be from the main inlet water circuit 51 to the main outlet water circuit 52. During this process, part of the water flow in the main water circuit 5 will flow to the water branch circuit 6, and the water flow in the water branch circuit 6 can flow to the sensible heat circulation device 2 to heat compressor 1, thereby evaporating the refrigerant in compressor 1 and discharging it from compressor 1, thus improving the reliability of compressor 1 during startup. Since the heat exchange area of ​​the sensible heat circulation device 2 is large and the water flow is in a flowing state, the heat exchange efficiency of the sensible heat circulation device 2 is higher than that of the electric heating belt while ensuring the water flow rate, thus effectively reducing the time and energy consumption required to heat compressor 1.

[0044] In addition, such as Figure 1 and Figure 2 As shown, according to a second aspect of the present invention, a control method for a low-temperature heat pump system is provided, wherein the low-temperature heat pump system is as described above, and the control method for the low-temperature heat pump system includes: controlling the sensible heat circulation device 2 to exchange heat with the compressor 1 by controlling the opening and closing of the water pump 63 and the electric valve 64.

[0045] Specifically, such as Figure 1 and Figure 2 As shown in the embodiment, before the compressor 1 starts at low temperature, the water temperature in the water circuit branch loop 6 is higher than the temperature of the refrigerant and refrigeration oil inside the compressor 1, and the casing 10 of the compressor 1 will be heated during the circulation process. When the main water circuit 5 is in a circulating state, the water pump 63 can be turned off, and the water in the main water circuit 5 can flow to the water circuit branch loop 6 by itself. The electric valve 64 opens, allowing the water to flow in the sensible heat circulation device 2 to heat the compressor 1. When the main water circuit 5 is in a non-circulating state, the water pump 63 turns on, and the water in the main water circuit 5 flows to the water circuit branch loop 6 under the drive of the water pump 63. The electric valve 64 opens, allowing the water to flow in the sensible heat circulation device 2 to heat the compressor 1. Thereafter, when the casing 10 of the compressor 1 is heated to the preset temperature, the compressor 1 can start normally.

[0046] Preferred, such as Figure 1 and Figure 2As shown in the embodiment, after the compressor 1 starts at low temperature, the main water circuit 5 of the low-temperature heat pump system remains in a circulating state, so the water pump 63 can be turned off to reduce energy consumption. When the compressor 1 is a low-pressure chamber compressor, the electric valve 64 is opened or closed according to the performance requirements of the low-temperature heat pump system. Specifically, since the oil sump of the low-pressure chamber compressor is located on the low-pressure side, it has higher requirements for oil temperature. Therefore, the electric valve 64 can be kept open to utilize the sensible heat circulation device 2 to ensure the superheat of the oil, thereby ensuring the reliability of the compressor 1. However, since the temperature of the low-pressure chamber compressor is low, long-term operation will have a certain impact on the water temperature of the low-temperature heat pump system, thereby affecting the performance of the low-temperature heat pump system. Therefore, whether the electric valve 64 is opened or closed can be determined according to the performance requirements of the low-temperature heat pump system.

[0047] When compressor 1 is a high-pressure compressor, since the oil sump of the high-pressure compressor is located on the high-pressure side, its exhaust superheat is relatively high. Therefore, in order to enable the system to reach a suitable exhaust superheat as quickly as possible, the electric valve 64 should be closed after the high-pressure compressor starts at low temperature. After the stable exhaust superheat required by the high-pressure compressor is established, the electric valve 64 can be opened. Because the temperature of the high-pressure compressor is relatively high, it can increase the water temperature of the low-temperature heat pump system during water circulation, thereby improving the performance of the low-temperature heat pump system.

[0048] During use, the low-temperature heat pump system can improve the reliability of compressor 1's low-temperature start-up. The sensible heat circulation device 2 is installed on compressor 1. After compressor 1 starts at low temperature, if compressor 1 is a low-pressure chamber compressor, the sensible heat circulation device 2 continues to work to ensure the reliability of compressor 1 during operation; if compressor 1 is a high-pressure chamber compressor, the sensible heat circulation device 2 continues to work to improve the performance of the low-temperature heat pump system, provided that the exhaust superheat is guaranteed.

[0049] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for a low-temperature heat pump system, characterized in that, The low-temperature heat pump system includes: compressor; A sensible heat circulation device is installed on the compressor, and the sensible heat circulation device is capable of exchanging heat with the compressor; Evaporator, connected to the compressor; A water-side heat exchanger is connected to the compressor and the evaporator; The main water circuit is connected to the water-side heat exchanger; and A branch water circuit is connected to the main water circuit, and the branch water circuit is connected to the sensible heat circulation device. Water in the branch water circuit circulates through the sensible heat circulation device. The main water circuit includes an inlet main circuit and an outlet main circuit. The inlet main circuit is connected to the inlet of the water-side heat exchanger, and the outlet main circuit is connected to the outlet of the water-side heat exchanger. The branch water circuit includes an inlet branch circuit and an outlet branch circuit. The inlet branch circuit is connected to the inlet main circuit, and the outlet branch circuit is connected to the outlet main circuit. The waterway branch circuit also includes: A water pump, installed in the inlet branch or the outlet branch, is used to provide power for the water circulation in the water circuit branch; and An electric valve is installed in the inlet branch or the outlet branch, and the electric valve is used to control the on / off state of the water circuit branch. The control method of the low-temperature heat pump system includes: controlling the sensible heat circulation device to exchange heat with the compressor by controlling the opening and closing of the water pump and the electric valve; After the compressor starts at low temperature, the water pump is turned off. When the compressor is a low-pressure chamber compressor, the electric valve opens or closes according to the performance requirements of the low-temperature heat pump system; When the compressor is a high-pressure chamber compressor, the electric valve is closed first, and then opened after the stable exhaust superheat required by the compressor is established.

2. The control method for a low-temperature heat pump system according to claim 1, characterized in that, Before the compressor starts at low temperature, When the main water circuit is in a circulating flow state, the water pump is turned off and the electric valve is turned on; When the main water circuit is in a non-circulating flow state, the water pump is turned on and the electric valve is turned on.

3. The control method for a low-temperature heat pump system according to claim 1, characterized in that, The sensible heat circulation device is formed in a strip shape and is arranged circumferentially around the outer periphery of the compressor. The two ends of the sensible heat circulation device are respectively provided with a water inlet and a water outlet. The water inlet branch is connected to the water inlet, and the water outlet branch is connected to the water outlet.

4. The control method for a low-temperature heat pump system according to claim 3, characterized in that, The sensible heat circulation device is located around the lower end of the compressor casing, or around the outer periphery of the compressor's lower cover. A temperature sensor is installed on the compressor casing. When the temperature detected by the temperature sensor is higher than a preset temperature, the compressor can be started.

5. The control method for a low-temperature heat pump system according to claim 3, characterized in that, The inner surface of the sensible heat circulation device is attached to the outer surface of the compressor, and the inner surface of the sensible heat circulation device is made of a thermally conductive material.

6. The control method for a low-temperature heat pump system according to claim 1, characterized in that, The low-temperature heat pump system also includes: A throttling device is disposed between the water-side heat exchanger and the evaporator, and the throttling device is connected to the water-side heat exchanger and the evaporator via a pipeline; and A fan is located on the side of the evaporator and is used to blow air onto the evaporator.

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