Air conditioning system and control method

Abstract

The present disclosure relates to an air-conditioning system and a control method. The air-conditioning system includes a compressor, an outdoor heat exchanger and an indoor heat exchanger. The refrigerant discharged from the compressor passes through the outdoor heat exchanger and the indoor heat exchanger and returns to the compressor, or the refrigerant discharged from the compressor passes through the indoor heat exchanger and the outdoor heat exchanger and returns to the compressor; it also includes: a subcooler, which is arranged on the connecting pipeline between the outdoor heat exchanger and the indoor heat exchanger; a liquid storage part, which is arranged on the connecting pipeline between the subcooler and the outdoor heat exchanger; a first pipeline, whose first end is connected to the outlet of the compressor and the second end is connected to the liquid storage part; and a pressure valve, which is arranged on the first pipeline. When the pressure valve is opened, the first pipeline is connected, which is equivalent to shielding the pressure loss of the outdoor heat exchanger, directly drawing out the high-pressure gaseous refrigerant from the outlet of the compressor, and directly pouring it into the liquid storage part, providing greater flow power for the liquid refrigerant in the liquid storage part, and improving the low-temperature starting speed.

Description

Technical Field

[0001] The present disclosure relates to the technical field of air conditioning, and in particular to an air conditioning system and a control method thereof. Background Art

[0002] When the air conditioning system is started at low temperatures, the system contains liquid refrigerant, so the cooling capacity demand is low, resulting in a low frequency of the compressor. This will cause insufficient power and fail to promote the refrigerant circulation, resulting in a slow startup speed. Summary of the Invention

[0003] Some embodiments of the present disclosure provide an air conditioning system and a control method for alleviating the problem of slow startup at low temperatures.

[0004] In one aspect of the present disclosure, an air conditioning system is provided, comprising a compressor, an outdoor heat exchanger, and an indoor heat exchanger, wherein refrigerant discharged from the compressor passes through the outdoor heat exchanger and the indoor heat exchanger and returns to the compressor, or the refrigerant discharged from the compressor passes through the indoor heat exchanger and the outdoor heat exchanger and returns to the compressor; and further comprising:

[0005] a subcooler, provided on the connecting pipe between the outdoor heat exchanger and the indoor heat exchanger;

[0006] a liquid storage component, provided on the connecting pipeline between the subcooler and the outdoor heat exchanger;

[0007] a first pipeline, a first end of which is connected to the outlet of the compressor, and a second end of which is connected to the liquid storage member; and

[0008] The pressure valve is provided on the first pipeline.

[0009] In some embodiments, the air conditioning system further includes a first throttle member, which is disposed in the first pipeline.

[0010] In some embodiments, the air-conditioning system further includes a second pipeline, a third pipeline, a fourth pipeline and a fifth pipeline, the subcooler includes a first flow path and a second flow path, the first end of the first flow path is connected to the liquid storage component through the second pipeline, and the second end of the first flow path is connected to the indoor heat exchanger through the third pipeline; the first end of the second flow path is connected to the liquid storage component through the fourth pipeline, and the second end of the second flow path is connected to the inlet of the compressor through the fifth pipeline.

[0011] In some embodiments, the air conditioning system further includes a first expansion valve, which is disposed in the fourth pipeline.

[0012] In some embodiments, the air conditioning system further includes a sixth pipeline, a first end of the sixth pipeline is connected to the fifth pipeline, and a second end of the sixth pipeline is connected to the enthalpy increase port of the compressor.

[0013] In some embodiments, the air conditioning system further includes a second expansion valve, which is disposed in the sixth pipeline.

[0014] In some embodiments, the air conditioning system further includes a first valve, which is disposed on the fifth pipeline and configured to control the opening and closing of the pipeline between the fifth pipeline and the inlet of the compressor.

[0015] In some embodiments, the air-conditioning system further includes a sixth pipeline, a first end of the sixth pipeline being connected to the fifth pipeline, and a second end of the sixth pipeline being connected to the enthalpy increase port of the compressor; wherein the first valve is close to the inlet of the compressor relative to the connection between the sixth pipeline and the fifth pipeline.

[0016] In some embodiments, the air conditioning system further includes a control valve, which includes four interfaces, and the four interfaces are respectively connected to the outlet of the compressor, the outdoor heat exchanger, the indoor heat exchanger and the fifth pipeline.

[0017] In some embodiments, the air-conditioning system further includes a sixth pipeline, a first end of the sixth pipeline being connected to the fifth pipeline, and a second end of the sixth pipeline being connected to the enthalpy increase port of the compressor; wherein the connection between the sixth pipeline and the fifth pipeline is closer to the inlet of the compressor relative to the connection between the control valve and the fifth pipeline.

[0018] In some embodiments, the air-conditioning system further includes a first valve, which is provided in the fifth pipeline and is configured to control the on-off of the pipeline between the fifth pipeline and the inlet of the compressor; wherein the first valve is close to the inlet of the compressor relative to the connection between the sixth pipeline and the fifth pipeline.

[0019] In some embodiments, the outdoor heat exchanger comprises a water-cooled plate heat exchanger.

[0020] In some embodiments, the air-conditioning system further includes an oil-gas separator provided at the outlet of the compressor, and the refrigerant discharged from the compressor first passes through the oil-gas separator before entering the indoor heat exchanger or the outdoor heat exchanger.

[0021] In some embodiments, the air-conditioning system further includes a gas-liquid separator provided at the inlet of the compressor, and the refrigerant flowing through the outdoor heat exchanger or the indoor heat exchanger and returning to the inlet of the compressor first passes through the gas-liquid separator before entering the inlet of the compressor.

[0022] In one aspect of the present disclosure, a control method for the above-mentioned air-conditioning system is provided, which includes:

[0023] After the air-conditioning system starts to run for the first preset time, if the ratio of the target value of the required cooling capacity or heating capacity to the rated value of the cooling capacity or heating capacity of the air-conditioning system is ≤ the first preset value A, and after continuing to run for the second preset time, the saturation temperature corresponding to the pressure at the outlet of the compressor is ≤ the first preset temperature value T1, and the actual exhaust temperature at the outlet of the compressor is ≥ the second preset temperature value T2, then the pressurizing valve is opened, where T2>T1.

[0024] In some embodiments, the pressurizing valve is closed when at least one of the following conditions is met:

[0025] Shut down the computer;

[0026] Shutdown;

[0027] The pressurizing valve is opened and continues to operate for a third preset time, and the saturation temperature corresponding to the pressure at the outlet of the compressor is greater than or equal to the third preset temperature T3;

[0028] The pressurizing valve is opened and continues to operate for a third preset time, and the difference between the actual exhaust temperature at the compressor outlet and the saturation temperature corresponding to the pressure at the compressor outlet is less than a fourth preset temperature T4; wherein T3>T4.

[0029] In some embodiments, the air conditioning system further includes a second pipeline, a third pipeline, a fourth pipeline, a fifth pipeline, a sixth pipeline, a first valve, a first expansion valve, and a second expansion valve; the subcooler includes a first flow path and a second flow path, the first end of the first flow path is connected to the liquid storage member through the second pipeline, and the second end of the first flow path is connected to the indoor heat exchanger through the third pipeline; the first end of the second flow path is connected to the liquid storage member through the fourth pipeline, and the second end of the second flow path is connected to the inlet of the compressor through the fifth pipeline; the first expansion valve is provided on the fourth pipeline; the first end of the sixth pipeline is connected to the fifth pipeline, and the second end of the sixth pipeline is connected to the enthalpy increase port of the compressor; the second expansion valve is provided on the sixth pipeline, and the first valve is provided on the fifth pipeline. The first valve is configured to control the connection and disconnection of the pipeline between the fifth pipeline and the inlet of the compressor, and the control method includes:

[0030] After the air-conditioning system starts to run for the first preset time, in the cooling mode, the saturation temperature corresponding to the pressure at the compressor inlet is ≥ the fifth preset temperature T5; in the heating mode, the saturation temperature corresponding to the pressure at the compressor outlet is ≤ the sixth preset temperature T6; and the difference between the actual temperature at the compressor outlet and the saturation temperature corresponding to the pressure at the compressor outlet is ≥ the seventh preset temperature T7, then the air-conditioning system enters the enthalpy increase mode; wherein, T6>T5.

[0031] In some embodiments, after the air conditioning system enters the enthalpy increase mode, the following actions are performed:

[0032] The compressor operates at the frequency required for the set target temperature. In cooling mode, if the saturation temperature corresponding to the compressor inlet pressure is lower than the saturation temperature corresponding to the compressor inlet pressure required for the set target temperature, the compressor frequency is reduced; otherwise, the compressor frequency is increased; in heating mode, if the saturation temperature corresponding to the compressor outlet pressure is lower than the saturation temperature corresponding to the compressor inlet pressure required for the set target temperature, the compressor frequency is increased; otherwise, the compressor frequency is reduced;

[0033] If the actual temperature difference between the outlet and inlet of the subcooler is greater than or equal to the target temperature difference between the outlet and inlet of the subcooler required for the set target temperature, the opening of the first expansion valve is increased; otherwise, the opening of the first expansion valve is decreased;

[0034] Close the first valve;

[0035] Open the second expansion valve to its maximum degree.

[0036] In some embodiments, the air conditioning system exits the enthalpy increase mode when at least one of the following conditions is met:

[0037] Shut down the computer;

[0038] Shutdown;

[0039] After entering the enthalpy increase mode and running for the third preset time, in cooling mode, the saturation temperature corresponding to the pressure at the compressor inlet is ≤ the eighth preset temperature T8; in heating mode, the saturation temperature corresponding to the pressure at the compressor outlet is ≥ the ninth preset temperature T9; wherein T9>T8;

[0040] After entering the enthalpy increase mode and running for the third preset time, the difference between the actual exhaust temperature at the outlet of the compressor and the saturation temperature corresponding to the pressure at the outlet of the compressor is less than the tenth preset temperature T10.

[0041] In some embodiments, the air conditioning system performs the following actions when exiting the enthalpy increase mode:

[0042] The compressor maintains the current frequency operation;

[0043] If the actual temperature difference between the outlet and inlet of the subcooler is greater than the target temperature difference between the outlet and inlet of the subcooler required for the set target temperature, the opening of the first expansion valve is increased; otherwise, the opening of the first expansion valve is decreased;

[0044] Open the first valve;

[0045] Close the second expansion valve.

[0046] Based on the above technical solution, the present disclosure has at least the following beneficial effects:

[0047] In some embodiments, a first end of the first pipeline is connected to the outlet of the compressor, and a second end of the first pipeline is connected to the liquid storage member. During low-temperature startup, such as low-temperature cooling, minimum cooling, or low-load heating, the pressurizing valve is opened, the first pipeline is connected, and the first pipeline directly draws high-pressure gaseous refrigerant from the outlet of the compressor and directly injects it into the liquid storage member. This is equivalent to shielding the pressure loss of the outdoor heat exchanger, providing greater flow power for the liquid refrigerant in the liquid storage member, increasing the refrigerant flow to the indoor heat exchanger, and improving the refrigerant pushing capacity, thereby increasing the low-temperature startup speed, improving the low-temperature cooling, minimum cooling, or low-load heating capabilities, and thus improving the system's operating capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings described herein are used to provide a further understanding of the present disclosure and constitute a part of this application. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation of the present disclosure. In the drawings:

[0049] Figure 1 A schematic diagram of an air conditioning system according to some embodiments of the present disclosure;

[0050] Figure 2 A schematic diagram of a cooling enthalpy increase mode of an air-conditioning system according to some embodiments of the present disclosure;

[0051] Figure 3 This is a schematic diagram of a heating enthalpy increase mode of an air-conditioning system provided according to some embodiments of the present disclosure.

[0052] The reference numerals in the accompanying drawings are described as follows:

[0053] 1- compressor; 2- outdoor heat exchanger; 3- indoor heat exchanger; 4- control valve; 5- subcooler; 6- liquid storage; 7- pressurizing valve; 8- oil-gas separator; 9- gas-liquid separator;

[0054] 11-first pipeline; 12-second pipeline; 13-third pipeline; 14-fourth pipeline; 15-fifth pipeline; 16-sixth pipeline; 17-seventh pipeline; 18-eighth pipeline;

[0055] 21-first expansion valve; 22-second expansion valve; 23-third expansion valve;

[0056] 31-first valve; 32-second valve; 33-third valve; 34-fourth valve; 35-fifth valve;

[0057] 41-first throttle valve; 42-second throttle valve; 43-third throttle valve;

[0058] 51-First flow path; 52-Second flow path;

[0059] 61 - first one-way valve; 62 - second one-way valve; 63 - third one-way valve.

[0060] It should be understood that the size of each part shown in the drawings is not drawn according to the actual proportional relationship.In addition, the same or similar reference numerals represent the same or similar components. DETAILED DESCRIPTION

[0061] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the present disclosure, its application, or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments herein. These embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, the composition of materials, numerical expressions, and numerical values set forth in these embodiments should be interpreted as being merely exemplary and not as limiting.

[0062] The terms "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. The terms "include" or "comprises" and similar terms mean that the elements before the term include the elements listed after the term, and do not exclude the possibility of also including other elements. The terms "upper", "lower", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0063] In the present disclosure, when a specific device is described as being located between a first device and a second device, an intervening device may or may not be present between the specific device and the first device or the second device. When a specific device is described as being connected to another device, the specific device may be directly connected to the other device without an intervening device, or may be not directly connected to the other device but with an intervening device.

[0064] All terms (including technical or scientific terms) used in this disclosure have the same meaning as those understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined herein.

[0065] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0066] Figure 1 is a schematic diagram of some embodiments of the air conditioning system according to the present disclosure. Figure 1 In some embodiments, the air-conditioning system includes a compressor 1, an outdoor heat exchanger 2 and an indoor heat exchanger 3. The refrigerant discharged from the compressor 1 passes through the outdoor heat exchanger 2 and the indoor heat exchanger 3 and returns to the compressor 1, or the refrigerant discharged from the compressor 1 passes through the indoor heat exchanger 3 and the outdoor heat exchanger 2 and returns to the compressor 1.

[0067] In some embodiments, the air conditioning system is a cooling-only unit, a heating-only unit, or a heating-only unit capable of both cooling and heating. The air conditioning system includes one outdoor unit and one indoor unit, or one outdoor unit and multiple indoor units (multi-split system).

[0068] In some embodiments, the air conditioning system further includes a subcooler 5 , which is disposed on a connecting pipe between the outdoor heat exchanger 2 and the indoor heat exchanger 3 .

[0069] In some embodiments, the air conditioning system further includes a liquid storage component 6 , which is disposed on a connecting pipeline between the subcooler 5 and the outdoor heat exchanger 2 .

[0070] In some embodiments, the air conditioning system further includes a first pipeline 11 , a first end of the first pipeline 11 is connected to the outlet of the compressor 1 , and a second end of the first pipeline 11 is connected to the liquid storage member 6 .

[0071] In some embodiments, the air conditioning system further includes a pressurizing valve 7 , which is disposed on the first pipeline 11 .

[0072] During low-temperature refrigeration, the frequency of the compressor 1 is low due to the low demand for refrigeration capacity. This results in insufficient power and an inability to promote refrigerant circulation, which in turn results in low low-temperature refrigeration capacity.

[0073] Based on this, the first end of the first pipeline 11 in the embodiment of the present disclosure is connected to the outlet of the compressor 1, and the second end of the first pipeline 11 is connected to the liquid storage part 6. During low-temperature startup, for example: low-temperature refrigeration, minimum refrigeration or low-load heating, the pressurizing valve 7 is opened, the first pipeline 11 is connected, and the first pipeline 11 directly draws out the high-pressure gaseous refrigerant from the outlet of the compressor 1, and directly pressurizes and injects it into the liquid storage part 6, which is equivalent to shielding the pressure loss of the outdoor heat exchanger 2, providing greater flow power for the liquid refrigerant in the liquid storage part 6, increasing the refrigerant flow to the indoor heat exchanger 3, and improving the refrigerant pushing capacity, thereby increasing the low-temperature startup speed, improving the ability of low-temperature refrigeration or minimum refrigeration, or low-load heating, and thus improving the system operation capacity.

[0074] In some embodiments, the compressor 1 comprises a jet enthalpy increase compressor.

[0075] In some embodiments, the indoor heat exchanger 3 includes one, two, three, four or more heat exchangers.

[0076] In some embodiments, the air conditioning system includes a first throttle member 41 , which is disposed on the first pipeline 11 .

[0077] Optionally, the first throttle member 41 includes a capillary tube.

[0078] In some embodiments, the air conditioning system further includes a third expansion valve 23 , which is disposed on a connecting pipe between the liquid storage element 6 and the outdoor heat exchanger 2 .

[0079] Optionally, the third expansion valve 23 includes an electronic expansion valve.

[0080] In some embodiments, the multi-connection system further includes a first one-way valve 61 , which is connected in parallel with the third expansion valve 23 , the inlet of the first one-way valve 61 is connected to the outdoor heat exchanger 2 , and the outlet of the first one-way valve 61 is connected to the liquid storage part 6 .

[0081] In some embodiments, the air conditioning system further includes a second pipeline 12 , a third pipeline 13 , a fourth pipeline 14 and a fifth pipeline 15 .

[0082] The subcooler 5 includes a first flow path 51 and a second flow path 52 .

[0083] A first end of the first flow path 51 is connected to the liquid storage member 6 through the second pipe 12 , and a second end of the first flow path 51 is connected to the indoor heat exchanger 3 through the third pipe 13 .

[0084] A first end of the second flow path 52 is connected to the liquid storage member 6 through the fourth pipe 14 , and a second end of the second flow path 52 is connected to the inlet of the compressor 1 through the fifth pipe 15 .

[0085] In some embodiments, the air conditioning system further includes a first expansion valve 21 , which is disposed in the fourth pipeline 14 .

[0086] Optionally, the first expansion valve 21 includes an electronic expansion valve.

[0087] In some embodiments, the air conditioning system further includes a sixth pipeline 16 , a first end of the sixth pipeline 16 is connected to the fifth pipeline 15 , and a second end of the sixth pipeline 16 is connected to the enthalpy increase port of the compressor 1 .

[0088] The sixth pipeline 16 is used to guide the refrigerant passing through the subcooler 5 to the enthalpy increasing port of the compressor 1 to achieve the jet enthalpy increasing effect of the compressor 1.

[0089] The enthalpy increase port of the compressor 1 is arranged in the medium-pressure chamber of the compressor 1 .

[0090] In some embodiments, the air conditioning system further includes a second expansion valve 22 , which is disposed in the sixth pipeline 16 .

[0091] The second expansion valve 22 comprises an electronic expansion valve. Using a highly precise electronic expansion valve enables smooth regulation of stepless heat injection and precise control of heat injection according to the unit's state, improving comfort and reliability while also stabilizing energy efficiency transitions.

[0092] In some embodiments, the air conditioning system further includes a first valve 31 , which is disposed on the fifth pipeline 15 . The first valve 31 is configured to control the connection and disconnection of the pipeline between the fifth pipeline 15 and the inlet of the compressor 1 .

[0093] In some embodiments, the air-conditioning system also includes a sixth pipeline 16, the first end of the sixth pipeline 16 is connected to the fifth pipeline 15, and the second end of the sixth pipeline 16 is connected to the enthalpy increase port of the compressor 1; wherein the first valve 31 is close to the inlet of the compressor 1 relative to the connection between the sixth pipeline 16 and the fifth pipeline 15.

[0094] In some embodiments, the air conditioning system further includes a control valve 4 , which includes four interfaces, which are respectively connected to the outlet of the compressor 1 , the outdoor heat exchanger 2 , the indoor heat exchanger 3 and the fifth pipeline 15 .

[0095] The control valve 4 is configured to return the refrigerant discharged from the compressor 1 to the compressor 1 through the outdoor heat exchanger 2 and the indoor heat exchanger 3 , or to return the refrigerant discharged from the compressor 1 to the compressor 1 through the indoor heat exchanger 3 and the outdoor heat exchanger 2 .

[0096] In some embodiments, the control valve 4 comprises a four-way valve.

[0097] In some embodiments, the air-conditioning system also includes a sixth pipeline 16, the first end of the sixth pipeline 16 is connected to the fifth pipeline 15, and the second end of the sixth pipeline 16 is connected to the enthalpy increase port of the compressor 1; wherein, the connection between the sixth pipeline 16 and the fifth pipeline 15 is close to the inlet of the compressor 1 relative to the connection between the control valve 4 and the fifth pipeline 15.

[0098] In some embodiments, the air-conditioning system further includes a first valve 31, which is provided in the fifth pipeline 15, and the first valve 31 is configured to control the on-off of the pipeline between the fifth pipeline 15 and the inlet of the compressor 1; wherein, the first valve 31 is close to the inlet of the compressor 1 relative to the connection between the sixth pipeline 16 and the fifth pipeline 15.

[0099] In some embodiments, the outdoor heat exchanger 2 includes a water-cooled plate heat exchanger.

[0100] The water-cooled plate heat exchanger exchanges heat with the refrigerant through circulating water.

[0101] The disclosed embodiment adopts a water-cooled plate heat exchanger. Since the refrigerant directly exchanges heat with water, its heat exchange effect is much higher than that of an air source heat exchanger. Therefore, the outdoor unit is small in size, which is more conducive to the transportation and installation of the unit and occupies a smaller area. In addition, the water-cooled plate heat exchanger does not need to exchange heat with the air. Therefore, the water source can be installed in a small machine room without the need for dedicated air ducts and other equipment. By adopting a water-cooled plate heat exchanger, the unit has a smaller volume for storing refrigerant. By cooperating with the first pipeline 1 and the liquid storage part 6, the refrigerant can be more concentrated to drive the rapid flow of liquid refrigerant, thereby achieving a rapid response of the refrigerant fluidity, thereby improving the energy efficiency of the unit and improving the comfort of use.

[0102] In some embodiments, the air conditioning system further includes an oil-gas separator 8 provided at the outlet of the compressor 1. The refrigerant discharged from the compressor 1 first passes through the oil-gas separator 8 before entering the indoor heat exchanger 3 or the outdoor heat exchanger 2. The oil-gas separator 8 is used to separate oil and gas.

[0103] In some embodiments, the air conditioning system further includes a second one-way valve 62, which is provided on the connecting pipeline between the compressor 1 and the oil-gas separator 8. The inlet of the second one-way valve 62 is connected to the outlet of the compressor 1, and the outlet of the second one-way valve 62 is connected to the oil-gas separator 8.

[0104] In some embodiments, the air conditioning system further includes a third one-way valve 63, which is disposed on the connecting pipeline between the oil-gas separator 8 and the control valve 4. The inlet of the third one-way valve 63 is connected to the oil-gas separator 8, and the outlet of the third one-way valve 63 is connected to the control valve 4.

[0105] In some embodiments, the air conditioning system further includes a seventh pipeline 17 and a second valve 32. A first end of the seventh pipeline 17 is connected to the oil-gas separator 8, and a second end of the seventh pipeline 17 is connected to the inlet of the compressor 1. The second valve 32 is provided on the seventh pipeline 17 and is used to control the opening and closing of the seventh pipeline 17.

[0106] In some embodiments, the air conditioning system further includes a second throttle valve 42 , which is disposed on the seventh pipeline 17 .

[0107] In some embodiments, the air-conditioning system further includes a gas-liquid separator 9 provided at the inlet of the compressor 1 . The refrigerant flowing through the outdoor heat exchanger 2 or the indoor heat exchanger 3 and returning to the inlet of the compressor 1 first passes through the gas-liquid separator 9 before entering the inlet of the compressor 1 .

[0108] In some embodiments, the fifth pipeline 15 is connected to the inlet of the compressor 1 through the gas-liquid separator 9. The first end of the fifth pipeline 15 is connected to the second flow path 52, and the second end of the fifth pipeline 15 is connected to the gas-liquid separator 9, which is connected to the inlet of the compressor 1.

[0109] In some embodiments, the air conditioning system further includes an eighth pipeline 18 , a first end of the eighth pipeline 18 is connected to the indoor unit 3 , a second end of the eighth pipeline 18 is connected to the gas-liquid separator 9 , and the gas-liquid separator 9 is connected to the inlet of the compressor 2 .

[0110] In some embodiments, the air conditioning system further includes a third throttle valve 43 , which is disposed on the eighth pipeline 18 .

[0111] The following combination Figures 1 to 3 Some specific embodiments of the air-conditioning system, as well as the cooling enthalpy increase mode and the heating enthalpy increase mode of the air-conditioning system are described in detail.

[0112] like Figure 1 As shown, the outlet of the compressor 1 is connected to the oil-gas separator 8 via the second one-way valve 62, and the oil-gas separator 8 is connected to the third one-way valve 63 and the seventh pipeline 17, respectively. The seventh pipeline 17 is connected to the inlet of the compressor 1, and the second valve 32 and the second throttle valve 42 are provided on the seventh pipeline 17. The third one-way valve 63 is connected to the first interface of the control valve 4, the second interface of the control valve 4 is connected to the outdoor heat exchanger 2, the third interface of the control valve 4 is connected to the indoor heat exchanger 3, and the fourth interface of the controller 4 is connected to the fifth pipeline 15. The first interface of the control valve 4 can be connected to the second interface, and the third interface of the controller 4 is connected to the fourth interface. Alternatively, the first interface of the control valve 4 is connected to the third interface, and the second interface of the control valve 4 is connected to the fourth interface.

[0113] The outdoor heat exchanger 2 is also connected in sequence to the third expansion valve 23, the liquid storage element 6, and the subcooler 5. The first one-way valve 6 is connected in parallel with the third expansion valve 23.

[0114] Subcooler 5 includes a first flow path 51 and a second flow path 52. A first end of first flow path 51 is connected to liquid reservoir 6 via second pipeline 12, and a second end of first flow path 51 is connected to indoor heat exchanger 3 via third pipeline 13. A first end of second flow path 52 is connected to liquid reservoir 6 via fourth pipeline 14, and a second end of second flow path 52 is connected to the inlet of compressor 1 via fifth pipeline 15. First expansion valve 21 is provided in fourth pipeline 14.

[0115] The first end of the sixth pipeline 16 is connected to the fifth pipeline 15, and the second end of the sixth pipeline 16 is connected to the enthalpy increase port of the compressor 1. The second expansion valve 22 is provided on the sixth pipeline 16. The connection between the sixth pipeline 16 and the fifth pipeline 15 is closer to the inlet of the compressor 1 than the connection between the control valve 4 and the fifth pipeline 15. The first valve 31 is provided on the fifth pipeline 15, closer to the inlet of the compressor 1 than the connection between the sixth pipeline 16 and the fifth pipeline 15.

[0116] The fifth pipeline 15 is connected to the inlet of the compressor 1 through the gas-liquid separator 9. The first end of the fifth pipeline 15 is connected to the second flow path 52, and the second end of the fifth pipeline 15 is connected to the gas-liquid separator 9. The gas-liquid separator 9 is connected to the inlet of the compressor 1.

[0117] A first end of the eighth pipe 18 is connected to the indoor unit 3 , a second end of the eighth pipe 18 is connected to the gas-liquid separator 9 , and the gas-liquid separator 9 is connected to the inlet of the compressor 2 .

[0118] A third valve 33 is installed on the pipeline connecting the third pipeline 13 to the indoor heat exchanger 3 to control the pipeline's on-off function. A fourth valve 34 is installed on the pipeline connecting the third port of the control valve 4 to the indoor heat exchanger 3 to control the pipeline's on-off function. A fifth valve 35 is installed on the eighth pipeline 18 to control the pipeline's on-off function.

[0119] like Figure 2 As shown in Figure 2, the refrigerant flow of the air-conditioning system in the cooling enthalpy increase mode.

[0120] Main circuit: high-temperature and high-pressure gas refrigerant discharged from the outlet of compressor 1 -> oil-gas separator 8 -> first and second interfaces of control valve 4 -> outdoor heat exchanger 2 (function: condensation and heat release) -> third expansion valve 23 (state: fully open) -> second pipeline 12 -> first flow path 51 of subcooler 5 -> third pipeline 13 -> third valve 33 -> indoor heat exchanger 3 (function: evaporator, evaporation and heat absorption, lowering indoor temperature) -> third and fourth interfaces of control valve 4 -> gas-liquid separator 9 -> inlet of compressor 1 (compressor 1 performs the next compression cycle).

[0121] Pressurized branch: When low-temperature cooling is used, the pressurized valve 7 is opened, and the high-temperature and high-pressure gaseous refrigerant is directly pressed into the liquid storage part 6, providing greater flow power for the liquid refrigerant in the liquid storage part 6, thereby achieving an increase in the mass flow rate of the indoor unit and ultimately improving the capacity at low load.

[0122] The refrigerant flowing out of the liquid storage member 6 is divided into two paths. One path flows to the first flow path 51 of the subcooler 5 , and the other path passes through the first expansion valve 21 into the second flow path 52 of the subcooler 5 and then enters the fifth pipeline 15 .

[0123] The refrigerant in the second flow path 52 of the subcooler 5 flows to the fifth pipeline 15. When the first valve 31 is closed, the refrigerant enters the sixth pipeline 16 and enters the enthalpy injection port of the compressor 1 through the second expansion valve 22, thereby increasing enthalpy and improving efficiency.

[0124] The refrigerant in the second flow path 52 of the subcooler 5 flows to the fifth pipeline 15 , the first valve 31 is opened, and the refrigerant enters the gas-liquid separator 9 through the first valve 31 and then enters the inlet of the compressor 1 through the gas-liquid separator 9 .

[0125] In the refrigeration enthalpy increase mode, since the enthalpy difference between the indoor unit and the outdoor unit remains unchanged, although the refrigerant density will be slightly reduced due to the existence of the enthalpy increase branch, the mass flow rate will increase slightly or remain unchanged due to the increase in the refrigerant flow rate flowing into the indoor unit, and the enthalpy increase system will also increase the supercooling degree. At the same time, under the same target capacity, compressor 1 can achieve frequency reduction, which greatly increases the system power reduction and thus improves the refrigeration energy efficiency.

[0126] like Figure 2 As shown in the figure, the refrigerant flow direction of the air-conditioning system in the heating enthalpy increase mode.

[0127] Main circuit: high-temperature and high-pressure gas refrigerant at the outlet of compressor 1 -> oil-gas separator 8 -> first and third interfaces of control valve 4 -> indoor heat exchanger 3 (function: condenser, condensation releases heat, increases indoor temperature) -> subcooler 5 -> third expansion valve 23 (state: throttling and pressure reduction) -> outdoor heat exchanger 2 (function: evaporation and heat absorption) -> second and fourth interfaces of control valve 4 -> gas-liquid separator -> inlet of compressor 1 (compressor 1 performs the next compression cycle).

[0128] Pressurized branch: When heating at low load, the pressurized valve 7 is opened, and the high-temperature and high-pressure gaseous refrigerant is directly pressed into the liquid storage part 6, providing greater flow power for the liquid refrigerant in the liquid storage part 6, thereby achieving an increase in the mass flow rate of the indoor unit and ultimately improving the capacity at low load.

[0129] The refrigerant in the second flow path 52 of the subcooler 5 flows to the fifth pipeline 15, the first valve 31 is closed, and the refrigerant enters the sixth pipeline 16 and enters the enthalpy injection port of the compressor 1 through the second expansion valve 22, thereby increasing enthalpy and improving efficiency.

[0130] The refrigerant in the second flow path 52 of the subcooler 5 flows to the fifth pipeline 15 , the first valve 31 is opened, and the refrigerant enters the gas-liquid separator 9 through the first valve 31 and then enters the inlet of the compressor 1 through the gas-liquid separator 9 .

[0131] In the heating enthalpy increase mode, combined with a subcooler, the enthalpy difference between the evaporator inlet and outlet can be increased, the refrigerant flow at the compressor outlet can be increased, and the work done in the compression process can be improved, thereby significantly increasing the heating capacity of the system.

[0132] Some embodiments further provide a method for controlling the air conditioning system, comprising:

[0133] After the air-conditioning system starts to run for the first preset time, if the ratio of the target value of the required cooling capacity or heating capacity to the rated value of the cooling capacity or heating capacity of the air-conditioning system is ≤ the first preset value A, and after continuing to run for the second preset time, the saturation temperature corresponding to the pressure at the outlet of the compressor 1 is ≤ the first preset temperature value T1, and the actual exhaust temperature at the outlet of the compressor 1 is ≥ the second preset temperature value T2, then the pressurizing valve 7 is opened, where T2>T1.

[0134] In some embodiments, the first preset time ranges from 0 min to 10 min. Optionally, the first preset time is 5 min.

[0135] In some embodiments, the second preset time ranges from 0 min to 10 min. Optionally, the second preset time is 5 min.

[0136] In some embodiments, the first preset value A ranges from 15% to 25%. Optionally, the first preset value A is 20%.

[0137] In some embodiments, the first preset temperature value T1 ranges from 20° C. to 30° C. Optionally, the first preset temperature value T1 is 25° C.

[0138] In some embodiments, the second preset temperature value T2 ranges from 45° C. to 55° C. Optionally, the second preset temperature value T2 is 50° C.

[0139] The pressure at the outlet of the compressor 1 is detected by a pressure detection element, and the saturation temperature corresponding to the pressure at the outlet of the compressor 1 is obtained by looking up a table.

[0140] The pressure at the inlet of the compressor 1 is detected by a pressure detection element, and the saturation temperature corresponding to the pressure at the inlet of the compressor 1 is obtained by looking up a table.

[0141] In some embodiments, the pressurizing valve 7 is closed when at least one of the following conditions is met:

[0142] Shut down the computer;

[0143] Shutdown (including shutdown after reaching the target temperature);

[0144] The pressurizing valve 7 is opened and continues to operate for a third preset time, and the saturation temperature corresponding to the pressure at the outlet of the compressor 1 is greater than or equal to the third preset temperature T3;

[0145] The pressurizing valve 7 is opened and continues to operate for a third preset time, and the difference between the actual exhaust temperature at the outlet of the compressor 1 and the saturation temperature corresponding to the pressure at the outlet of the compressor 1 is less than the fourth preset temperature T4;

[0146] Among them, T3>T4.

[0147] In some embodiments, the third preset temperature T3 is in the range of 30° C. to 40° C. Optionally, the third preset temperature T3 is 35° C.

[0148] In some embodiments, the fourth preset temperature T4 is in the range of 0° C. to 10° C. Optionally, the fourth preset temperature T4 is 5° C.

[0149] In some embodiments, the air conditioning system further includes a second pipeline 12, a third pipeline 13, a fourth pipeline 14, a fifth pipeline 15, a sixth pipeline 16, a first valve 31, a first expansion valve 21, and a second expansion valve 22; the subcooler 5 includes a first flow path 51 and a second flow path 52, a first end of the first flow path 51 is connected to the liquid storage member 6 through the second pipeline 12, and a second end of the first flow path 51 is connected to the indoor heat exchanger 3 through the third pipeline 13; a first end of the second flow path 52 is connected to the indoor heat exchanger 3 through the fourth pipeline 14 is connected to the liquid storage member 6, and the second end of the second flow path 52 is connected to the inlet of the compressor 1 through the fifth pipeline 15; the first expansion valve 21 is provided on the fourth pipeline 14; the first end of the sixth pipeline 16 is connected to the fifth pipeline 15, and the second end of the sixth pipeline 16 is connected to the enthalpy increase port of the compressor 1; the second expansion valve 22 is provided on the sixth pipeline 16, and the first valve 31 is provided on the fifth pipeline 15. The first valve 31 is configured to control the pipeline between the fifth pipeline 15 and the inlet of the compressor 1. The control method includes:

[0150] After the air-conditioning system starts to run for the first preset time, in the cooling mode, the saturation temperature corresponding to the pressure at the inlet of the compressor 1 is ≥ the fifth preset temperature T5; in the heating mode, the saturation temperature corresponding to the pressure at the outlet of the compressor 1 is ≤ the sixth preset temperature T6; and the difference between the actual temperature at the outlet of the compressor 1 and the saturation temperature corresponding to the pressure at the outlet of the compressor 1 is ≥ the seventh preset temperature T7, then the air-conditioning system enters the enthalpy increase mode; wherein, T6>T5.

[0151] In some embodiments, the fifth preset temperature T5 ranges from 3° C. to 13° C. Optionally, the fifth preset temperature T5 is 8° C.

[0152] In some embodiments, the sixth preset temperature T6 ranges from 35° C. to 45° C. Optionally, the sixth preset temperature T6 is 40° C.

[0153] In some embodiments, the seventh preset temperature T7 is in the range of 15° C. to 25° C. Optionally, the seventh preset temperature T7 is 20° C.

[0154] In some embodiments, after the air conditioning system enters the enthalpy increase mode, the following actions are performed:

[0155] Compressor 1 operates at the frequency required by the set target temperature. In cooling mode, if the saturation temperature corresponding to the pressure at the inlet of compressor 1 is lower than the saturation temperature corresponding to the pressure at the inlet of compressor 1 required for the set target temperature, the frequency of compressor 1 is reduced; otherwise, the frequency of compressor 1 is increased. In heating mode, if the saturation temperature corresponding to the pressure at the outlet of compressor 1 is lower than the saturation temperature corresponding to the pressure at the inlet of compressor 1 required for the set target temperature, the frequency of compressor 1 is increased; otherwise, the frequency of compressor 1 is reduced.

[0156] If the actual temperature difference between the outlet and the inlet of the second flow path 52 of the subcooler 5 is greater than or equal to the target temperature difference between the outlet and the inlet of the second flow path 52 of the subcooler 5 required for the set target temperature, the opening of the first expansion valve 21 is increased; otherwise, the opening of the first expansion valve 21 is decreased;

[0157] Close the first valve 31;

[0158] The second expansion valve 22 is opened to the maximum degree.

[0159] In some embodiments, the air conditioning system exits the enthalpy increase mode when at least one of the following conditions is met:

[0160] Shut down the computer;

[0161] Shutdown (including shutdown after reaching the target temperature);

[0162] After entering the enthalpy increase mode and running for the third preset time, in the cooling mode, the saturation temperature corresponding to the pressure at the inlet of the compressor 1 is ≤ the eighth preset temperature T8; in the heating mode, the saturation temperature corresponding to the pressure at the outlet of the compressor 1 is ≥ the ninth preset temperature T9; wherein T9>T8;

[0163] After entering the enthalpy increase mode and running for the third preset time, the difference between the actual exhaust temperature at the outlet of the compressor 1 and the saturation temperature corresponding to the pressure at the outlet of the compressor 1 is less than the tenth preset temperature T10.

[0164] In some embodiments, the third preset time ranges from 5 minutes to 15 minutes. Optionally, the third preset time is 10 minutes.

[0165] In some embodiments, the eighth preset temperature T8 has a value range of -10°C to 0°C. Optionally, the eighth preset temperature T8 is -5°C.

[0166] In some embodiments, the ninth preset temperature T9 is in the range of 45° C. to 55° C. Optionally, the ninth preset temperature T9 is 50° C.

[0167] In some embodiments, the tenth preset temperature T10 ranges from 0° C. to 10° C. Optionally, the tenth preset temperature T10 is 5° C.

[0168] In some embodiments, the air conditioning system exits the enthalpy increase mode and performs the following actions:

[0169] Compressor 1 maintains the current frequency operation;

[0170] If the actual temperature difference between the outlet and the inlet of the second flow path 52 of the subcooler 5 is greater than the target temperature difference between the outlet and the inlet of the second flow path 52 of the subcooler 5 corresponding to the set target temperature, the opening of the first expansion valve 21 is increased; otherwise, the opening of the first expansion valve 21 is decreased;

[0171] Open the first valve 31;

[0172] The second expansion valve 22 is closed.

[0173] The air-conditioning system provided by the embodiment of the present disclosure has the beneficial effects of improving energy efficiency, reducing costs, reducing weight, and high reliability.

[0174] Based on the above-mentioned embodiments of the present disclosure, in the absence of explicit negation or conflict, the technical features of one embodiment may be beneficially combined with one or more other embodiments.

[0175] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. An air conditioning system comprising a compressor (1), an outdoor heat exchanger (2) and an indoor heat exchanger (3), wherein the refrigerant discharged from the compressor (1) passes through the outdoor heat exchanger (2) and the indoor heat exchanger (3) and returns to the compressor (1), or the refrigerant discharged from the compressor (1) passes through the indoor heat exchanger (3) and the outdoor heat exchanger (2) and returns to the compressor (1), characterized in that: Also includes: A subcooler (5) is provided on the connecting pipeline between the outdoor heat exchanger (2) and the indoor heat exchanger (3); A liquid storage element (6) is provided on the connecting pipeline between the subcooler (5) and the outdoor heat exchanger (2); a first pipeline (11), a first end of which is connected to the outlet of the compressor (1) and a second end of which is connected to the liquid storage member (6); as well as A pressure valve (7) is provided on the first pipeline (11).

2. The air conditioning system according to claim 1, wherein: It comprises a first throttling member (41), wherein the first throttling member (41) is arranged on the first pipeline (11).

3. The air conditioning system according to claim 1, wherein: The subcooler (5) further comprises a second pipeline (12), a third pipeline (13), a fourth pipeline (14) and a fifth pipeline (15); the subcooler (5) comprises a first flow path (51) and a second flow path (52); the first end of the first flow path (51) is connected to the liquid storage component (6) through the second pipeline (12), and the second end of the first flow path (51) is connected to the indoor heat exchanger (3) through the third pipeline (13); the first end of the second flow path (52) is connected to the liquid storage component (6) through the fourth pipeline (14), and the second end of the second flow path (52) is connected to the inlet of the compressor (1) through the fifth pipeline (15).

4. The air conditioning system according to claim 3, wherein: It also includes a first expansion valve (21), wherein the first expansion valve (21) is provided in the fourth pipeline (14).

5. The air conditioning system according to claim 3, wherein: It also includes a sixth pipeline (16), a first end of the sixth pipeline (16) is connected to the fifth pipeline (15), and a second end of the sixth pipeline (16) is connected to the enthalpy increase port of the compressor (1).

6. The air conditioning system according to claim 5, wherein: It also includes a second expansion valve (22), which is arranged on the sixth pipeline (16).

7. The air conditioning system according to claim 3, wherein: The invention also includes a first valve (31), which is provided on the fifth pipeline (15). The first valve (31) is configured to control the opening and closing of the pipeline between the fifth pipeline (15) and the inlet of the compressor (1).

8. The air conditioning system according to claim 7, wherein: The invention also includes a sixth pipeline (16), a first end of the sixth pipeline (16) being connected to the fifth pipeline (15), and a second end of the sixth pipeline (16) being connected to the enthalpy increase port of the compressor (1); wherein the first valve (31) is close to the inlet of the compressor (1) relative to the connection between the sixth pipeline (16) and the fifth pipeline (15).

9. The air conditioning system according to claim 3, wherein: It also includes a control valve (4), which includes four interfaces, and the four interfaces are respectively connected to the outlet of the compressor (1), the outdoor heat exchanger (2), the indoor heat exchanger (3) and the fifth pipeline (15).

10. The air conditioning system according to claim 9, wherein: The invention also includes a sixth pipeline (16), wherein a first end of the sixth pipeline (16) is connected to the fifth pipeline (15), and a second end of the sixth pipeline (16) is connected to the enthalpy increase port of the compressor (1); wherein the connection between the sixth pipeline (16) and the fifth pipeline (15) is closer to the inlet of the compressor (1) than the connection between the control valve (4) and the fifth pipeline (15).

11. The air conditioning system according to claim 10, wherein: The invention also includes a first valve (31), which is provided on the fifth pipeline (15) and is configured to control the opening and closing of the pipeline between the fifth pipeline (15) and the inlet of the compressor (1); wherein the first valve (31) is close to the inlet of the compressor (1) relative to the connection between the sixth pipeline (16) and the fifth pipeline (15).

12. The air conditioning system according to claim 1, wherein: The outdoor heat exchanger (2) comprises a water-cooled plate heat exchanger.

13. The air conditioning system according to claim 1, wherein: It also includes an oil-gas separator (8) provided at the outlet of the compressor (1), and the refrigerant discharged from the compressor (1) first passes through the oil-gas separator (8) and then enters the indoor heat exchanger (3) or the outdoor heat exchanger (2).

14. The air conditioning system according to claim 1, wherein: It also includes a gas-liquid separator (9) provided at the inlet of the compressor (1), and the refrigerant flowing through the outdoor heat exchanger (2) or the indoor heat exchanger (3) and returning to the inlet of the compressor (1) first passes through the gas-liquid separator (9) before entering the inlet of the compressor (1).

15. A method for controlling an air conditioning system according to any one of claims 1 to 14, comprising: After the air-conditioning system starts to run for a first preset time, if the ratio of the target value of the required cooling capacity or heating capacity to the rated value of the cooling capacity or heating capacity of the air-conditioning system is ≤ the first preset value A, and after continuing to run for a second preset time, the saturation temperature corresponding to the pressure at the outlet of the compressor (1) is ≤ the first preset temperature value T1, and the actual exhaust temperature at the outlet of the compressor (1) is ≥ the second preset temperature value T2, then the pressurizing valve (7) is opened, wherein T2>T1.

16. The method for controlling an air conditioning system according to claim 15, comprising: When at least one of the following conditions is met, the pressure valve (7) is closed: Shut down the computer; Shutdown; The pressurizing valve (7) is opened and continues to operate for a third preset time, and the saturation temperature corresponding to the pressure at the outlet of the compressor (1) is greater than or equal to the third preset temperature T3; The pressurizing valve (7) is opened and continues to operate for a third preset time, and the difference between the actual exhaust temperature at the outlet of the compressor (1) and the saturation temperature corresponding to the pressure at the outlet of the compressor (1) is less than a fourth preset temperature T4; wherein T3>T4.

17. The control method of the air conditioning system according to claim 15, wherein: The air conditioning system further comprises a second pipeline (12), a third pipeline (13), a fourth pipeline (14), a fifth pipeline (15), a sixth pipeline (16), a first valve (31), a first expansion valve (21) and a second expansion valve (22); the subcooler (5) comprises a first flow path (51) and a second flow path (52); a first end of the first flow path (51) is connected to the liquid storage member (6) through the second pipeline (12), and a second end of the first flow path (51) is connected to the indoor heat exchanger (3) through the third pipeline (13); a first end of the second flow path (52) is connected to the liquid storage member (6) through the fourth pipeline (14). , the second end of the second flow path (52) is connected to the inlet of the compressor (1) through the fifth pipeline (15); the first expansion valve (21) is provided on the fourth pipeline (14); the first end of the sixth pipeline (16) is connected to the fifth pipeline (15), and the second end of the sixth pipeline (16) is connected to the enthalpy increase port of the compressor (1); the second expansion valve (22) is provided on the sixth pipeline (16), and the first valve (31) is provided on the fifth pipeline (15), and the first valve (31) is configured to control the pipeline between the fifth pipeline (15) and the inlet of the compressor (1), and the control method includes: After the air-conditioning system starts to operate for a first preset time, in cooling mode, the saturation temperature corresponding to the pressure at the inlet of the compressor (1) is ≥ the fifth preset temperature T5; in heating mode, the saturation temperature corresponding to the pressure at the outlet of the compressor (1) is ≤ the sixth preset temperature T6; and the difference between the actual temperature at the outlet of the compressor (1) and the saturation temperature corresponding to the pressure at the outlet of the compressor (1) is ≥ the seventh preset temperature T7, then the air-conditioning system enters the enthalpy increase mode; wherein T6>T5.

18. The control method of the air conditioning system according to claim 17, wherein: After the air conditioning system enters the enthalpy increase mode, it performs the following actions: The compressor (1) operates at a frequency required for a set target temperature. In cooling mode, if the saturation temperature corresponding to the pressure at the inlet of the compressor (1) is lower than the saturation temperature corresponding to the pressure at the inlet of the compressor (1) required for the set target temperature, the frequency of the compressor (1) is reduced; otherwise, the frequency of the compressor (1) is increased. In heating mode, if the saturation temperature corresponding to the pressure at the outlet of the compressor (1) is lower than the saturation temperature corresponding to the pressure at the inlet of the compressor (1) required for the set target temperature, the frequency of the compressor (1) is increased; otherwise, the frequency of the compressor (1) is reduced. If the actual temperature difference between the outlet and the inlet of the subcooler (5) is greater than or equal to the target temperature difference between the outlet and the inlet of the subcooler (5) required for the set target temperature, the opening of the first expansion valve (21) is increased; otherwise, the opening of the first expansion valve (21) is decreased; closing the first valve (31); The second expansion valve (22) is opened to its maximum degree.

19. The control method of the air conditioning system according to claim 17, wherein: The air conditioning system exits the enthalpy increase mode when at least one of the following conditions is met: Shut down the computer; Shutdown; After entering the enthalpy increase mode and running for a third preset time, in the cooling mode, the saturation temperature corresponding to the pressure at the inlet of the compressor (1) is ≤ the eighth preset temperature T8; in the heating mode, the saturation temperature corresponding to the pressure at the outlet of the compressor (1) is ≥ the ninth preset temperature T9; wherein T9>T8; After entering the enthalpy increase mode and running for the third preset time, the difference between the actual exhaust temperature at the outlet of the compressor (1) and the saturation temperature corresponding to the pressure at the outlet of the compressor (1) is less than the tenth preset temperature T10.

20. The control method of the air conditioning system according to claim 19, wherein: When the air conditioning system exits the enthalpy increase mode, the following actions are performed: The compressor (1) maintains the current frequency operation; If the actual temperature difference between the outlet and the inlet of the subcooler (5) is greater than the target temperature difference between the outlet and the inlet of the subcooler (5) required for the set target temperature, the opening of the first expansion valve (21) is increased; otherwise, the opening of the first expansion valve (21) is decreased; Opening the first valve (31); Close the second expansion valve (22).

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