Heat pump system with double auxiliary valves

Abstract

The invention belongs to the technical field of heat pumps, and particularly relates to a double-auxiliary-valve heat pump system which comprises a compressor, a first heat exchanger and a second heat exchanger. The main path enters a main side of the economizer, a first auxiliary path which is communicated with an auxiliary side inlet of the economizer and is provided with a first auxiliary expansion valve is arranged on the main path between the economizer and the first heat exchanger, and an auxiliary side outlet of the economizer is communicated with an enthalpy supplementing air inlet; the main path between the economizer and the first heat exchanger is communicated with the enthalpy supplementing air inlet through a second auxiliary path provided with a second auxiliary expansion valve; and the control unit is used for controlling the second auxiliary expansion valve to be opened when the first auxiliary expansion valve is opened and the exhaust temperature is detected to be greater than an exhaust temperature threshold value. When the exhaust temperature is too high, the second auxiliary expansion valve is opened, and a refrigerant is cooled through the second auxiliary expansion valve and enters the compressor. And by supplementing the refrigerant with larger air quantity and lower temperature into the compressor, the exhaust temperature of the compressor is effectively reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of heat pumps, and specifically relates to a double auxiliary valve heat pump system. Background Art

[0002] When the first heat exchanger of the heat pump is in a low-temperature environment, the compressor exhaust temperature is high due to reasons such as the increase in the compressor compression ratio. The high compressor exhaust temperature will have many adverse effects on the heat pump system, such as causing serious attenuation of the heat exchange capacity of the heat pump system, decreased control stability, and easy occurrence of unit protection.

[0003] In the face of the problem of increased compressor exhaust temperature under the above-mentioned low temperature environment, the existing technology uses jet enthalpy increase to solve it. The principle is to add an economizer to the heat pump system, and the liquid refrigerant coming from the second heat exchanger is divided into a main route and an auxiliary route. The liquid refrigerant in the main route directly enters the economizer, and the liquid refrigerant in the auxiliary route becomes a gas-liquid mixed state after heat expansion, pressure reduction and temperature reduction after passing through the auxiliary expansion valve, and also enters the economizer. The refrigerant in the auxiliary route further cools the liquid refrigerant in the main route to make it supercooled. The supercooled refrigerant in the main route passes through the expansion valve into the first heat exchanger for heat exchange. The refrigerant in the auxiliary route absorbs the heat of the main route refrigerant and becomes a gas, which is sucked into the refrigerant replenishment inlet of the compressor and mixed with the refrigerant in the compressor with a higher temperature, thereby reducing the exhaust temperature of the compressor.

[0004] However, when the temperature of the liquid refrigerant coming out of the second heat exchanger is high, for example, when the water temperature on the second heat exchanger side of the heat pump is high, the liquid refrigerant in the main circuit heats the refrigerant in the auxiliary circuit, causing the temperature of the auxiliary circuit refrigerant to be relatively high. After the auxiliary circuit refrigerant with a relatively high temperature is sucked into the compressor, it cannot effectively reduce the exhaust temperature of the compressor. Summary of the invention

[0005] The present application provides a dual-auxiliary valve heat pump system to solve the technical problem that the existing jet enthalpy increase technology cannot effectively reduce the compressor exhaust temperature when the ambient temperature is low and the temperature of the liquid refrigerant coming out of the second heat exchanger is high.

[0006] The present application provides a double auxiliary valve heat pump system, the system comprising:

[0007] A compressor, a first heat exchanger, and a second heat exchanger, wherein the compressor suction port inhales refrigerant through a suction pipeline, the compressor exhaust port discharges refrigerant through an exhaust pipeline, and the second heat exchanger is connected to the first heat exchanger through a main path;

[0008] The main road enters the main side of the economizer, a first auxiliary road is provided on the main road between the economizer and the first heat exchanger, the first auxiliary road is communicated with the auxiliary side inlet of the economizer, the auxiliary side outlet of the economizer is communicated with the compressor enthalpy supplement air inlet, and a first auxiliary expansion valve is provided on the first auxiliary road;

[0009] The main path between the economizer and the first heat exchanger is connected to the compressor enthalpy supplement air inlet through a second auxiliary path, and a second auxiliary expansion valve is provided on the second auxiliary path;

[0010] The system further comprises a control unit, which is configured to:

[0011] When the first auxiliary expansion valve is opened, if it is detected that the exhaust temperature is greater than an exhaust temperature threshold, the second auxiliary expansion valve is controlled to be opened.

[0012] In the above preferred technical solution of the dual auxiliary valve heat pump system, the control unit is also used for:

[0013] When the first auxiliary expansion valve is opened, if it is detected that the exhaust temperature is greater than the exhaust temperature threshold, the opening degree of the second auxiliary expansion valve is adjusted according to the exhaust temperature.

[0014] In the above preferred technical solution of the dual auxiliary valve heat pump system, the control unit is specifically used for:

[0015] When it is detected that the exhaust temperature is greater than the exhaust temperature threshold, calculating the exhaust temperature difference between the exhaust temperature and the exhaust temperature target value;

[0016] The opening of the second auxiliary expansion valve is adjusted according to the numerical range of the exhaust temperature difference. The larger the upper limit of the numerical range of the exhaust temperature difference is, the larger the opening of the second auxiliary expansion valve is.

[0017] In the above preferred technical solution of the dual auxiliary valve heat pump system, the control unit is also used for:

[0018] detecting an inlet temperature of the auxiliary side of the economizer and an outlet temperature of the auxiliary side of the economizer;

[0019] The auxiliary side outlet temperature of the economizer is subtracted from the auxiliary side inlet temperature of the economizer to calculate the supplementary air superheat;

[0020] The opening degree of the first auxiliary expansion valve is adjusted according to the supplementary air superheat.

[0021] In the above preferred technical solution of the dual auxiliary valve heat pump system, the control unit is specifically used for:

[0022] Calculating the difference between the supplementary air superheat and the supplementary air superheat target value;

[0023] The opening of the first auxiliary expansion valve is adjusted according to the numerical range of the supplementary air superheat difference. The larger the upper limit of the numerical range of the supplementary air superheat difference is, the larger the opening of the first auxiliary expansion valve is.

[0024] In the above preferred technical solution of the double auxiliary valve heat pump system, a first main expansion valve is provided on the main path between the economizer and the first heat exchanger, and the control unit is further used for:

[0025] When the heat pump is in heating operation, detecting a first suction temperature of the compressor suction port and a first saturation temperature of the refrigerant in the suction pipeline;

[0026] subtracting the first saturation temperature from the first suction temperature to calculate a first suction superheat of the compressor;

[0027] The opening degree of the first main expansion valve is adjusted according to the first suction air superheat.

[0028] In the above preferred technical solution of the dual auxiliary valve heat pump system, the control unit is specifically used for:

[0029] calculating a first suction air superheat difference between the first suction air superheat and the first suction air superheat target value;

[0030] The opening of the first main expansion valve is adjusted according to the numerical range of the first intake superheat difference. The larger the upper limit of the numerical range of the first intake superheat difference is, the larger the opening of the first main expansion valve is.

[0031] In the above preferred technical solution of the double auxiliary valve heat pump system, a second main expansion valve is provided on the main line between the second heat exchanger and the economizer, and the control unit is further used for:

[0032] When the heat pump is in refrigeration operation, the first main expansion valve is controlled to be fully opened, and a second suction temperature of the compressor suction port and a second saturation temperature of the refrigerant in the suction pipeline are detected;

[0033] subtracting the second saturation temperature from the second suction temperature to calculate a second suction superheat of the compressor;

[0034] The opening degree of the second main expansion valve is adjusted according to the second suction air superheat.

[0035] In the above preferred technical solution of the dual auxiliary valve heat pump system, the control unit is specifically used for:

[0036] a second suction air superheat difference value according to the second suction air superheat value and the second suction air superheat target value;

[0037] The opening of the second main expansion valve is adjusted according to the numerical range of the second intake superheat difference. The larger the upper limit of the numerical range of the second intake superheat difference is, the larger the opening of the second main expansion valve is.

[0038] In the above preferred technical solution of the dual auxiliary valve heat pump system, the control unit is also used for:

[0039] When the heat pump is in heating operation, detecting the opening of the first main expansion valve;

[0040] When the opening degree of the first main expansion valve is less than the first main expansion valve opening degree threshold, the opening degree of the second main expansion valve is adjusted according to the opening degree of the first main expansion valve.

[0041] In the above-mentioned preferred technical solution of the double auxiliary valve heat pump system, the main path between the economizer and the first heat exchanger enters the heat pump control board radiator, so that the refrigerant in the main path reduces the temperature of the heat pump control board.

[0042] The present application provides a dual-auxiliary valve heat pump system, in which the first auxiliary expansion valve reduces the compressor exhaust temperature through the existing jet enthalpy increase technology. When the compressor exhaust temperature is high, the second auxiliary expansion valve is opened, and the refrigerant passing through the second auxiliary circuit is cooled and depressurized by heat expansion when passing through the second auxiliary expansion valve, and is sucked into the compressor through the refrigerant replenishment inlet. Since the refrigerant in the second auxiliary circuit will not be heated by the high-temperature refrigerant in the main circuit of the economizer, the temperature is relatively low, and after adding the second auxiliary circuit, the amount of air supplied to the compressor refrigerant replenishment inlet will also increase. Compared with the existing jet enthalpy increase technology, the dual auxiliary valve design of the present application can supply a larger amount of refrigerant with a lower temperature to the compressor refrigerant replenishment inlet, thereby effectively reducing the compressor exhaust temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0044] Figure 1 It is a schematic diagram of a double auxiliary valve heat pump system provided in an embodiment of the present application;

[0045] Figure 2 is a schematic diagram of another double auxiliary valve heat pump system provided in an embodiment of the present application;

[0046] Figure 3 This is another schematic diagram of a double auxiliary valve heat pump system provided in an embodiment of the present application;

[0047] Figure 4 This is a schematic diagram of another dual-auxiliary valve heat pump system provided in an embodiment of the present application.

[0048] Reference numerals:

[0049] 101- a first heat exchanger;

[0050] 102- second heat exchanger;

[0051] 103-inhalation pipeline;

[0052] 104-exhaust pipe;

[0053] 105-Main Road;

[0054] 106-Economizer;

[0055] 107-First Auxiliary Road;

[0056] 108- enthalpy supplement air inlet;

[0057] 109-first auxiliary expansion valve;

[0058] 110-Second Auxiliary Road;

[0059] 111 - second auxiliary expansion valve;

[0060] 201-first main expansion valve;

[0061] 301- second main expansion valve;

[0062] 302-four-way reversing valve;

[0063] 401-Heat pump control panel radiator.

[0064] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0066] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in sequences other than those illustrated or described herein, for example.

[0067] In the embodiments of the present application, the words "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0068] The heat pump consists of two heat exchangers. Generally, the first heat exchanger is placed outdoors for heat exchange with outdoor air, and the second heat exchanger is placed indoors for temperature regulation. The refrigerant circulates between the first heat exchanger and the second heat exchanger through a compressor.

[0069] When the first heat exchanger of the heat pump is in a low-temperature environment, the compressor exhaust temperature is high due to reasons such as the increase in the compressor compression ratio. The high compressor exhaust temperature will have many adverse effects on the heat pump system, such as causing serious attenuation of the heat exchange capacity of the heat pump system, decreased control stability, and easy occurrence of unit protection.

[0070] In the face of the problem of increased compressor exhaust temperature under the above-mentioned low temperature environment, the prior art uses jet reheat to solve it. The principle of jet reheat is to add an economizer to the heat pump system. The liquid refrigerant from the second heat exchanger is divided into a main route and an auxiliary route. The liquid refrigerant in the main route directly enters the economizer, and the liquid refrigerant in the auxiliary route becomes a gas-liquid mixed state after heat expansion, pressure reduction and temperature reduction when passing through the auxiliary expansion valve, and also enters the economizer. Because the refrigerant temperature in the auxiliary route is lower than that of the main route refrigerant, the refrigerant in the auxiliary route can further cool the liquid refrigerant in the main route, making the liquid refrigerant in the main route supercooled. The supercooled refrigerant in the main route passes through the expansion valve into the first heat exchanger for heat exchange. The refrigerant in the auxiliary route absorbs the heat of the main route refrigerant and becomes a medium-temperature gas, which is sucked into the refrigerant replenishment inlet of the compressor and mixed with the high-temperature refrigerant in the compressor, thereby reducing the exhaust temperature of the compressor.

[0071] However, when the temperature of the liquid refrigerant coming out of the second heat exchanger is relatively high, for example, when the water temperature on the second heat exchanger side of the heat pump is relatively high and heats the refrigerant in the second heat exchanger, the liquid refrigerant in the main circuit heats the refrigerant in the auxiliary circuit, causing the temperature of the auxiliary circuit refrigerant to be relatively high. After the auxiliary circuit refrigerant with a relatively high temperature is sucked into the compressor, it cannot effectively reduce the exhaust temperature of the compressor.

[0072] In order to solve the technical problem that the existing jet reheat technology cannot effectively reduce the compressor exhaust temperature when the ambient temperature is low and the temperature of the liquid refrigerant coming out of the second heat exchanger is high, the technical concept of the present application is: on the basis of jet reheat through the economizer, a second auxiliary road is added to the main road between the economizer and the first heat exchanger to connect with the reheat supplement air inlet of the compressor, and a second auxiliary expansion valve is arranged on the second auxiliary road. When the first auxiliary expansion valve is opened, if it is detected that the compressor exhaust temperature is too high, the second auxiliary expansion valve is opened.

[0073] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0074] First, the nouns appearing in this application are explained:

[0075] Refrigerant: The substance that transfers heat through evaporation or condensation in a heat pump system;

[0076] Heat exchanger: equipment used to exchange heat between refrigerant and water or air, including evaporator and condenser;

[0077] Economizer: A heat exchanger consisting of a primary side and a secondary side, used to reduce the temperature of the refrigerant on the primary side by allowing the refrigerant on the secondary side to reduce the temperature of the refrigerant on the primary side.

[0078] In a possible embodiment of the present application, a dual auxiliary valve heat pump system is provided. Figure 1 Schematic diagram of a double auxiliary valve heat pump system provided in an embodiment of the present application. Figure 1 As shown, the system includes:

[0079] A compressor, a first heat exchanger 101, and a second heat exchanger 102. The compressor suction port inhales refrigerant through a suction pipeline 103, and the compressor exhaust port discharges refrigerant through an exhaust pipeline 104. The second heat exchanger 102 is connected to the first heat exchanger 101 through a main path 105;

[0080] The main path 105 enters the main side of the economizer 106. A first auxiliary path 107 is provided on the main path 105 between the economizer 106 and the first heat exchanger 101. The first auxiliary path 107 is connected to the auxiliary side inlet of the economizer 106. The auxiliary side outlet of the economizer 106 is connected to the compressor enthalpy supplement air inlet 108. A first auxiliary expansion valve 109 is provided on the first auxiliary path 107.

[0081] The refrigerant in the main circuit 105 enters the first auxiliary expansion valve 109 through the first auxiliary circuit 107 to expand and cool down and enter the auxiliary side of the economizer 106, thereby cooling the refrigerant entering the main side of the economizer 106. After cooling down, the main side refrigerant enters the first heat exchanger 101 through the main circuit 105. Since the refrigerant in the main circuit 105 is cooled down, it can better evaporate and absorb heat in the first heat exchanger 101, thereby improving the heat exchange capacity of the heat pump system. At the same time, the refrigerant on the auxiliary side of the economizer 106 is sucked into the compressor through the enthalpy supplement inlet 108, in order to mix the lower temperature auxiliary side refrigerant with the high temperature compressor exhaust to reduce the exhaust temperature.

[0082] The main path 105 between the economizer 106 and the first heat exchanger 101 is connected to the compressor enthalpy supplement air inlet 108 through the second auxiliary path 110, and the second auxiliary expansion valve 111 is provided on the second auxiliary path 110;

[0083] The system further comprises a control unit, which is configured to:

[0084] When the first auxiliary expansion valve 109 is opened, if it is detected that the exhaust temperature is greater than the exhaust temperature threshold, the second auxiliary expansion valve 111 is controlled to be opened.

[0085] The existing heat pump system with jet enthalpy increase only includes the first auxiliary circuit 107 and the first auxiliary expansion valve 109. When the heating operation or the hot water operation is in progress, the temperature set by the user on the second heat exchanger 102 side may be relatively high, and the air temperature or water temperature on the second heat exchanger 102 side is also relatively high, thereby heating the refrigerant in the second heat exchanger 102. The refrigerant with a relatively high temperature in the second heat exchanger 102 enters the primary side of the economizer 106, and also heats the refrigerant on the auxiliary side, making the refrigerant temperature on the auxiliary side relatively high. After the refrigerant on the auxiliary side with a relatively high temperature is sucked into the compressor, it cannot effectively reduce the exhaust temperature of the compressor.

[0086] Therefore, in this embodiment, on the basis of the first auxiliary circuit 107 and the first auxiliary expansion valve 109, a second auxiliary circuit 110 and a second auxiliary expansion valve 111 are added to the main circuit 105. When the first auxiliary expansion valve 109 is opened, if it is detected that the exhaust temperature is greater than the exhaust temperature threshold, the second auxiliary expansion valve 111 is controlled to open. After the refrigerant in the main circuit 105 enters the second auxiliary circuit 110, it expands and cools in the second auxiliary expansion valve 111, and is then sucked into the compressor through the enthalpy supplementary air inlet 108 and mixed with the high-temperature exhaust gas. Since the refrigerant in the second auxiliary circuit 110 is not heated by the high-temperature refrigerant in the main circuit 105, the temperature of the refrigerant entering the compressor through the second auxiliary circuit 110 is lower than the temperature of the refrigerant in the first auxiliary circuit 107. In this embodiment, the exhaust temperature threshold can be set to 90°C.

[0087] In addition, the dual auxiliary circuit design in this embodiment can provide a larger air supply volume to the compressor compared to the single auxiliary circuit design in the existing jet enthalpy increase technology. Therefore, compared to the existing jet enthalpy increase technology, this embodiment can provide a larger amount of refrigerant gas with a lower temperature to the enthalpy increase air inlet 108 of the compressor, thereby effectively reducing the compressor exhaust temperature when the ambient temperature is low and the temperature of the liquid refrigerant coming out of the second heat exchanger is high.

[0088] In a possible embodiment of the present application, the control unit is further used for:

[0089] When the first auxiliary expansion valve 109 is opened, if it is detected that the exhaust temperature is greater than the exhaust temperature threshold, the opening degree of the second auxiliary expansion valve 111 is adjusted according to the exhaust temperature.

[0090] Specifically, a temperature sensor may be provided in the exhaust pipe 104 to detect the exhaust temperature of the compressor.

[0091] Optionally, the control unit is specifically used for:

[0092] When it is detected that the exhaust temperature is greater than the exhaust temperature threshold, the exhaust temperature difference between the exhaust temperature and the exhaust temperature target value is calculated;

[0093] The calculation method of this step is to subtract the exhaust temperature target value from the exhaust temperature to calculate the exhaust temperature difference.

[0094] The opening of the second auxiliary expansion valve 111 is adjusted according to the numerical range of the exhaust temperature difference. The larger the upper limit of the numerical range of the exhaust temperature difference is, the larger the opening of the second auxiliary expansion valve 111 is.

[0095] It should be noted that by increasing the opening of the second auxiliary expansion valve 111, the amount of low-temperature refrigerant supplied to the reheat supplement inlet 108 can be increased, thereby reducing the compressor exhaust temperature. Therefore, the higher the exhaust temperature, the larger the opening of the second auxiliary expansion valve 111.

[0096] The opening degree of the second auxiliary expansion valve 111 can be calculated by a preset value × exhaust temperature difference × preset step length, so as to achieve accurate adjustment of the opening degree according to the exhaust temperature, for example, it can be:

[0097] When △Td≥2, the second auxiliary expansion valve 111 is opened by 2×△Td×preset step size; when △Td≤-2, the second auxiliary expansion valve 111 is closed by 2×△Td×preset step size; when -2<△Td<2, the opening degree of the second auxiliary expansion valve 111 remains unchanged.

[0098] Among them, △Td is the exhaust temperature difference.

[0099] In a possible embodiment of the present application, the control unit is further used for:

[0100] Detecting the inlet temperature of the auxiliary side of the economizer 106 and the outlet temperature of the auxiliary side of the economizer 106;

[0101] In this step, a temperature sensor is provided at the inlet and outlet of the auxiliary side of the economizer 106 to detect the refrigerant temperature at the inlet and outlet of the auxiliary side of the economizer 106 .

[0102] The supplementary air superheat is calculated by subtracting the auxiliary side inlet temperature of the economizer 106 from the auxiliary side outlet temperature of the economizer 106;

[0103] It should be noted that the supplementary air superheat is the temperature difference between the refrigerant entering the auxiliary side of the economizer 106 and flowing out of the auxiliary side of the economizer 106 , reflecting the degree of heating of the refrigerant on the auxiliary side by the refrigerant on the primary side of the economizer 106 .

[0104] The opening degree of the first auxiliary expansion valve 109 is adjusted according to the superheat of the supplementary air.

[0105] Optionally, the control unit is specifically used for:

[0106] Calculate the difference between the supply air superheat degree and the supply air superheat degree target value;

[0107] The opening of the first auxiliary expansion valve 109 is adjusted according to the numerical range of the difference in superheat of the supplementary air. The larger the upper limit of the numerical range of the difference in superheat of the supplementary air is, the larger the opening of the first auxiliary expansion valve 109 is.

[0108] In this embodiment, the larger the opening of the first auxiliary expansion valve 109, the more refrigerant enters the auxiliary side of the economizer 106, which can reduce the degree of heating of the auxiliary side refrigerant by the main side refrigerant and reduce the supplementary air superheat of the auxiliary side refrigerant. When the supplementary air superheat of the auxiliary side refrigerant is reduced, the exhaust temperature of the compressor will also be reduced after the auxiliary side refrigerant enters the compressor through the supplementary enthalpy air inlet 108.

[0109] The opening degree of the first auxiliary expansion valve 109 can be calculated by a preset value × a difference in the superheat of the supplementary air × a preset step length, so as to achieve accurate adjustment of the opening degree according to the size of the superheat of the supplementary air, for example, it can be:

[0110] When △MSH≥2, the first auxiliary expansion valve 109 is opened by 2×△MSH×preset step size; when △MSH≤-2, the first auxiliary expansion valve 109 is closed by 2×△MSH×preset step size; when -2<△MSH<2, the opening of the first auxiliary expansion valve 109 remains unchanged.

[0111] Among them, △MSH is the difference in superheat of the supplementary air.

[0112] In a possible embodiment of the present application, another dual auxiliary valve heat pump system is provided. Figure 2 Schematic diagram of another dual auxiliary valve heat pump system provided in the embodiment of the present application. Figure 2 As shown, a first main expansion valve 201 is provided on the main path 105 between the economizer 106 and the first heat exchanger 101, and the control unit is also used for:

[0113] When the heat pump is in heating operation, the first suction temperature of the compressor suction port and the first saturation temperature of the refrigerant in the suction pipeline 103 are detected;

[0114] The saturation temperature is the temperature when the liquid and vapor are in a dynamic equilibrium state, that is, in a saturated state. When the saturation temperature is constant, the saturation pressure is also constant; conversely, when the saturation pressure is constant, the saturation temperature is also constant. In the suction line 103, the pressure of the refrigerant has a corresponding relationship with the saturation temperature of the refrigerant. Therefore, a low-pressure switch can be set in the suction line 103. By measuring the pressure of the refrigerant at the low-pressure switch, the first saturation temperature of the refrigerant in the suction line 103 can be calculated. By setting a temperature sensor in the suction line 103, the first suction temperature of the refrigerant at the suction port can be measured. Generally, since the refrigerant evaporates and absorbs heat in the first heat exchanger 101, the first suction temperature is higher than the first saturation temperature.

[0115] The first suction temperature is subtracted from the first saturation temperature to calculate the first suction superheat of the compressor;

[0116] The opening degree of the first main expansion valve 201 is adjusted according to the first suction air superheat.

[0117] It should be noted that the compressor sucks in the refrigerant through the suction line 103, compresses it and discharges it to the exhaust line 104. Therefore, the higher the temperature of the refrigerant sucked into the compressor, the higher the exhaust temperature of the compressor. The first suction superheat of the compressor reflects the difference between the actual temperature of the refrigerant sucked into the compressor and the saturation temperature. Therefore, it is necessary to adjust the opening of the first main expansion valve 201 according to the first suction superheat to adjust the suction superheat of the compressor. The ultimate goal is to keep the exhaust temperature of the compressor within a reasonable range.

[0118] Optionally, the control unit is specifically used for:

[0119] Calculate the first suction air superheat difference between the first suction air superheat and the first suction air superheat target value;

[0120] The opening of the first main expansion valve 201 is adjusted according to the numerical range of the first suction superheat difference. The larger the upper limit of the numerical range of the first suction superheat difference is, the larger the opening of the first main expansion valve 201 is.

[0121] Generally speaking, the reason why the first suction superheat is too high is that the refrigerant flow entering the first heat exchanger 101 is too small, and the refrigerant absorbs too much heat through evaporation. By increasing the opening of the first main expansion valve 201, the refrigerant flow entering the first heat exchanger 101 can be increased. The more the refrigerant flow, the lower the temperature of the refrigerant, thereby reducing the first suction superheat and ultimately reducing the exhaust temperature of the compressor.

[0122] The opening degree of the first main expansion valve 201 can be calculated by a preset value × a first suction superheat difference × a preset step length, so as to achieve accurate adjustment of the opening degree according to the first suction superheat, for example, it can be:

[0123] When △SSH1≥2, the first main expansion valve 201 is opened by 2×△SSH1×preset step size; when △SSH1≤-2, the first main expansion valve 201 is closed by 2×△SSH1×preset step size; when -2<△SSH1<2, the opening degree of the first main expansion valve 201 remains unchanged.

[0124] Among them, △SSH1 is the first suction superheat difference.

[0125] In a possible embodiment of the present application, another dual auxiliary valve heat pump system is provided. Figure 3 Schematic diagram of another dual auxiliary valve heat pump system provided in the embodiment of the present application, such as Figure 3 As shown, a second main expansion valve 301 is provided on the main path 105 between the second heat exchanger 102 and the economizer 106. To switch between heating operation and cooling operation, Figure 3 As shown, a four-way reversing valve 302 is also provided in the heat pump system.

[0126] In this embodiment, the control unit is also used for:

[0127] When the heat pump is in refrigeration operation, the first main expansion valve 201 is controlled to be fully opened, and the second suction temperature of the compressor suction port and the second saturation temperature of the refrigerant in the suction pipeline 103 are detected;

[0128] It should be noted that when the heat pump is in refrigeration operation, the control unit controls the four-way reversing valve 302 to switch, so that one refrigerant inlet and outlet of the second heat exchanger 102 is connected to the suction pipeline 103, thereby switching the second heat exchanger 102 to an evaporator; the control unit controls the four-way reversing valve 302 to switch, so that one refrigerant inlet and outlet of the first heat exchanger 101 is connected to the exhaust pipeline 104, thereby switching the first heat exchanger 101 to a condenser. After the first heat exchanger 101 is switched to a condenser, the refrigerant flows out from the first heat exchanger 101 to the first main expansion valve 201, so the first main expansion valve 201 is controlled to be fully opened.

[0129] Specifically, as in the above embodiment, the second saturation temperature is calculated by detecting the refrigerant pressure in the suction pipeline 103, and the second suction temperature of the refrigerant at the suction port is detected by a temperature sensor.

[0130] Subtract the second saturation temperature from the second suction temperature to calculate the second suction superheat of the compressor;

[0131] The opening degree of the second main expansion valve 301 is adjusted according to the second suction air superheat.

[0132] Since a refrigerant inlet and outlet of the second heat exchanger 102 is connected to the suction pipeline 103, the compressor inhales refrigerant from the second heat exchanger 102. As in the above embodiment, a high second suction superheat will cause a high compressor exhaust temperature, and the reason for the high second suction superheat is that the refrigerant flow entering the second heat exchanger 102 is too small, and the refrigerant absorbs too much heat when evaporating, so by adjusting the opening of the second main expansion valve 301, the refrigerant flow entering the second heat exchanger 102 is adjusted to achieve the adjustment of the compressor exhaust temperature.

[0133] Optionally, the control unit is specifically used for:

[0134] a second suction air superheat difference value according to the second suction air superheat value and the second suction air superheat target value;

[0135] The opening of the second main expansion valve 301 is adjusted according to the numerical range of the second suction superheat difference. The larger the upper limit of the numerical range of the second suction superheat difference is, the larger the opening of the second main expansion valve 301 is.

[0136] When the second suction superheat is too high, the opening of the second main expansion valve 301 is increased to increase the refrigerant flow entering the second heat exchanger 102, thereby reducing the second suction superheat to reduce the compressor exhaust temperature.

[0137] The opening degree of the second main expansion valve 301 can be calculated by a preset value×a second suction superheat difference×a preset step length, so as to achieve accurate adjustment of the opening degree according to the second suction superheat, for example, it can be:

[0138] When △SSH≥2, the second main expansion valve 301 is opened by 2×△SSH2×preset step size; when △SSH2≤-2, the second main expansion valve 301 is closed by 2×△SSH2×preset step size; when -2<△SSH2<2, the opening degree of the second main expansion valve 301 remains unchanged.

[0139] Among them, △SSH2 is the second suction superheat difference.

[0140] Based on the above embodiment, in a possible embodiment of the present application, the control unit is further used for:

[0141] When the heat pump is in heating operation, the opening degree of the first main expansion valve 201 is detected;

[0142] When the opening degree of the first main expansion valve 201 is less than the opening degree threshold of the first main expansion valve 201 , the opening degree of the second main expansion valve 301 is adjusted according to the opening degree of the first main expansion valve 201 .

[0143] In the actual operation of the heat pump system of the present application, when the heating operation is performed, if the opening degree of the first main expansion valve 201 is relatively low, for example 100 steps, the valve body control accuracy of the first main expansion valve 201 is seriously reduced, and each valve body opening adjustment has a greater impact on the heat pump system. To avoid this situation, the second main expansion valve 301 participates in the control and adjustment during the heating operation.

[0144] In this embodiment, the opening degree of the second main expansion valve 301 can be calculated by the following formula:

[0145] The opening degree of the second main expansion valve 301 = 200 + the opening degree of the first main expansion valve 201 × 2.8

[0146] During heating operation, the control stability of the heat pump system can be improved by enabling the first main expansion valve 201 and the second main expansion valve 301 to participate in the regulation at the same time.

[0147] Based on the above embodiments, in a possible embodiment of the present application, another dual auxiliary valve heat pump system is provided. Figure 4 Schematic diagram of another dual auxiliary valve heat pump system provided in the embodiment of the present application. Figure 4 As shown, the main path 105 between the economizer 106 and the first heat exchanger 101 enters the heat pump control board radiator 401, so that the refrigerant in the main path 105 reduces the temperature of the heat pump control board.

[0148] In the existing heat pump system, the heat pump control board dissipates heat through air cooling. When the indoor temperature is high, the air cooling method cannot effectively reduce the temperature of the control board, causing the heat pump system to malfunction. In this embodiment, the refrigerant in the main circuit 105 is introduced into the heat pump control board radiator 401, and the control board is liquid-cooled by the refrigerant in the main circuit 105. Compared with the existing air cooling method, this heat dissipation method has higher stability and better cooling effect on the control board.

[0149] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments, and the above embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A double auxiliary valve heat pump system, characterized in that: The system comprises: A compressor, a first heat exchanger, and a second heat exchanger, wherein the compressor suction port inhales refrigerant through a suction pipeline, the compressor exhaust port discharges refrigerant through an exhaust pipeline, and the second heat exchanger is connected to the first heat exchanger through a main path; The main road enters the main side of the economizer, a first auxiliary road is provided on the main road between the economizer and the first heat exchanger, the first auxiliary road is communicated with the auxiliary side inlet of the economizer, the auxiliary side outlet of the economizer is communicated with the compressor enthalpy supplement air inlet, and a first auxiliary expansion valve is provided on the first auxiliary road; The main path between the economizer and the first heat exchanger is connected to the compressor enthalpy supplement air inlet through a second auxiliary path, and a second auxiliary expansion valve is provided on the second auxiliary path; The system further comprises a control unit, which is configured to: When the first auxiliary expansion valve is opened, if it is detected that the exhaust temperature is greater than an exhaust temperature threshold, the second auxiliary expansion valve is controlled to be opened.

2. The system according to claim 1, characterized in that The control unit is also used for: When the first auxiliary expansion valve is opened, if it is detected that the exhaust temperature is greater than the exhaust temperature threshold, the opening degree of the second auxiliary expansion valve is adjusted according to the exhaust temperature.

3. The system according to claim 2, characterized in that The control unit is specifically used for: When it is detected that the exhaust temperature is greater than the exhaust temperature threshold, calculating the exhaust temperature difference between the exhaust temperature and the exhaust temperature target value; The opening of the second auxiliary expansion valve is adjusted according to the numerical range of the exhaust temperature difference. The larger the upper limit of the numerical range of the exhaust temperature difference is, the larger the opening of the second auxiliary expansion valve is.

4. The system according to claim 1, characterized in that The control unit is also used for: detecting an inlet temperature of the auxiliary side of the economizer and an outlet temperature of the auxiliary side of the economizer; The auxiliary side outlet temperature of the economizer is subtracted from the auxiliary side inlet temperature of the economizer to calculate the supplementary air superheat; The opening degree of the first auxiliary expansion valve is adjusted according to the supplementary air superheat.

5. The system according to claim 4, characterized in that The control unit is specifically used for: Calculating the difference between the supplementary air superheat and the supplementary air superheat target value; The opening of the first auxiliary expansion valve is adjusted according to the numerical range of the supplementary air superheat difference. The larger the upper limit of the numerical range of the supplementary air superheat difference is, the larger the opening of the first auxiliary expansion valve is.

6. The system according to claim 1, characterized in that A first main expansion valve is provided on the main circuit between the economizer and the first heat exchanger, and the control unit is further used for: When the heat pump is in heating operation, detecting a first suction temperature of the compressor suction port and a first saturation temperature of the refrigerant in the suction pipeline; subtracting the first saturation temperature from the first suction temperature to calculate a first suction superheat of the compressor; The opening degree of the first main expansion valve is adjusted according to the first suction air superheat.

7. The system according to claim 6, characterized in that The control unit is specifically used for: calculating a first suction air superheat difference between the first suction air superheat and the first suction air superheat target value; The opening of the first main expansion valve is adjusted according to the numerical range of the first intake superheat difference. The larger the upper limit of the numerical range of the first intake superheat difference is, the larger the opening of the first main expansion valve is.

8. The system according to claim 6, characterized in that A second main expansion valve is provided on the main circuit between the second heat exchanger and the economizer, and the control unit is further used for: When the heat pump is in refrigeration operation, the first main expansion valve is controlled to be fully opened, and a second suction temperature of the compressor suction port and a second saturation temperature of the refrigerant in the suction pipeline are detected; subtracting the second saturation temperature from the second suction temperature to calculate a second suction superheat of the compressor; The opening degree of the second main expansion valve is adjusted according to the second suction air superheat.

9. The system according to claim 8, characterized in that The control unit is specifically used for: a second suction air superheat difference value according to the second suction air superheat degree and the second suction air superheat degree target value; The opening of the second main expansion valve is adjusted according to the numerical range of the second intake superheat difference. The larger the upper limit of the numerical range of the second intake superheat difference is, the larger the opening of the second main expansion valve is.

10. The system according to claim 8, characterized in that The control unit is also used for: When the heat pump is in heating operation, detecting the opening of the first main expansion valve; When the opening degree of the first main expansion valve is less than the first main expansion valve opening degree threshold, the opening degree of the second main expansion valve is adjusted according to the opening degree of the first main expansion valve.

11. The system according to any one of claims 1 to 10, characterized in that: The main path between the economizer and the first heat exchanger enters the heat pump control board radiator, so that the refrigerant in the main path reduces the temperature of the heat pump control board.

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