A control method of an air conditioning system and an air conditioning system

Abstract

The application discloses a control method of an air conditioning system and the air conditioning system. The air conditioning system comprises a heating circuit and a refrigerating circuit. The outdoor condenser is arranged in the refrigerating circuit, and the indoor condenser is arranged in the heating circuit. The capacity of the outdoor condenser is greater than that of the indoor condenser. The air conditioning system further comprises a liquid accumulator. The liquid accumulator has two inlets. The two inlets are provided with one-way valve devices for unidirectionally leading the liquid accumulator. The heating circuit is unidirectionally led to the indoor condenser through one of the one-way valve devices, and the refrigerating circuit is unidirectionally led to the outdoor condenser through the other one-way valve device. When the heating circuit is operated, the supercooling degree of the liquid accumulator is detected. When the supercooling degree is higher than a first supercooling degree preset value, the refrigerating circuit is simultaneously started. In this way, when the working medium filling amount of the whole system is greater than the working requirement of the indoor condenser, the supercooling degree is reduced by simultaneously starting the refrigerating circuit.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and more specifically to a control method for an air conditioning system and an air conditioning system. Background Technology

[0002] An air conditioning system includes an outdoor condenser and an indoor condenser. To ensure system performance, the outdoor condenser has a larger capacity than the indoor condenser. This means that the amount of refrigerant required in cooling mode is greater than that required in heating mode. To maintain system consistency, the system is charged according to the maximum refrigerant charge, that is, according to the amount of refrigerant required in cooling mode.

[0003] Thus, in heating mode, the large amount of refrigerant charged will increase the subcooling of the receiver, causing the system to malfunction. Summary of the Invention

[0004] This invention provides a control method for an air conditioning system. The air conditioning system includes a heating circuit and a cooling circuit. The cooling circuit has an outdoor condenser, and the heating circuit has an indoor condenser. The capacity of the outdoor condenser is larger than that of the indoor condenser. The air conditioning system also includes a liquid receiver with two inlets. Each inlet is equipped with a one-way valve device that allows one-way communication between the liquid receiver and the heating circuit. The heating circuit is unidirectionally connected to the indoor condenser through one of the one-way valve devices, and the cooling circuit is unidirectionally connected to the outdoor condenser through the other one-way valve device. The control method includes the following steps:

[0005] When the heating circuit is running, the subcooling degree of the liquid receiver is detected. When the subcooling degree is higher than the first subcooling degree preset value, the cooling circuit is started at the same time.

[0006] In one specific implementation, one of the following steps is also included:

[0007] S1: After the refrigeration circuit has been started for a set time, the refrigeration circuit is then turned off;

[0008] S2: After the first execution of step S1, execute step S1 at least once at a predetermined interval;

[0009] S3: After starting the refrigeration circuit, if the subcooling reaches the required value, the refrigeration circuit will be shut down.

[0010] In one specific implementation, in step S2, at least one preset value for subcooling is set in a sequentially decreasing manner, and all of them are less than the first preset value for subcooling. The detected subcooling is compared with the corresponding preset value for subcooling according to the number of times step S1 is executed. If it is greater than the corresponding preset value for subcooling, then step S1 is executed again.

[0011] In one specific embodiment, when the heating circuit is running, the subcooling degree of the liquid receiver is detected. If the subcooling degree is lower than the second subcooling degree preset value, the heating circuit is temporarily shut down and the cooling circuit is started for a predetermined time. If the subcooling degree is not lower than the second subcooling degree preset value, the cooling circuit is shut down and the heating circuit is restarted.

[0012] In one specific embodiment, before starting the heating circuit, the pressure ratio of the high and low pressure of the compressor is detected. When the pressure ratio of the high and low pressure of the compressor is less than the preset pressure ratio value, the cooling circuit is started first. When the pressure ratio of the high and low pressure of the air conditioning system reaches the preset pressure ratio value, the heating circuit is started and the cooling circuit is shut down.

[0013] The present invention also provides an air conditioning system, including a heating circuit and a cooling circuit. The cooling circuit is provided with an outdoor condenser, and the heating circuit is provided with an indoor condenser. The capacity of the outdoor condenser is greater than that of the indoor condenser. The system also includes a detection element for detecting the subcooling of the indoor condenser, and a control unit connected to the detection element. The control unit has a first subcooling preset value stored in its memory. When the heating circuit is running, if the control unit determines that the detected subcooling is higher than the first subcooling preset value, it simultaneously starts the cooling circuit. After starting the cooling circuit, if the detected subcooling reaches the required value, the cooling circuit is shut down.

[0014] In one specific embodiment, the system further includes a liquid receiver having two inlets. Each of the two inlets is equipped with a one-way valve device that unidirectionally connects the liquid receiver. The heating circuit unidirectionally connects the indoor condenser and the liquid receiver through one of the one-way valve devices, and the cooling circuit unidirectionally connects the outdoor condenser and the liquid receiver through the other one-way valve device.

[0015] In one specific embodiment, the detection element includes a first temperature detection unit and a second temperature detection unit. The first temperature detection unit is located between the indoor condenser and the liquid receiver, and the second temperature detection unit is located at the outlet of the liquid receiver or in a pipeline connected to the outlet. The subcooling is obtained by the temperature difference of the refrigerant at the location of the first temperature detection unit and the location of the second temperature detection unit.

[0016] In one specific embodiment, the system further includes an intermediate heat exchanger, a front evaporator, and a battery cooler. The intermediate heat exchanger includes a first inlet, a first outlet, a second inlet, and a second outlet. The outlet of the liquid receiver is connected to the first inlet of the intermediate heat exchanger, the first outlet is connected to the inlet of the front evaporator, the outlet of the front evaporator is connected to the second inlet, the second outlet is connected to the compressor, and the first outlet is connected to the battery cooler.

[0017] In this scheme, when the subcooling of the receiver exceeds the preset first subcooling value during the operation of the heating circuit, the refrigeration circuit is simultaneously activated. Since the heating circuit is in operation and its pressure is higher, the pressure inside the receiver is greater than the pressure of the newly activated refrigeration circuit. The working medium will not circulate in the refrigeration circuit; instead, it will be stored in the outdoor condenser and the piping between the receiver and compressor. This is equivalent to distributing a certain amount of working medium upstream of the receiver in the refrigeration circuit for storage by simultaneously activating the refrigeration circuit, thereby reducing the amount of working medium entering the indoor condenser in the heating circuit and lowering its subcooling. Thus, when the capacity of the outdoor condenser is greater than that of the indoor condenser, and the total working medium charge of the system exceeds the operating requirements of the indoor condenser, the subcooling of the receiver can be reduced by conditionally activating the refrigeration circuit while the heating circuit is running, allowing the system to meet the requirements. Attached Figure Description

[0018] Figure 1 This is a schematic block diagram showing the connection of the air conditioning system in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram illustrating the parameter variation relationship in the air conditioning system control method provided in the embodiments of the present invention.

[0020] Figure 1 The annotations in the attached figures are explained as follows:

[0021] 1-Compressor;

[0022] 2-Outdoor condenser;

[0023] 3-Liquid reservoir;

[0024] 4-Indoor condenser;

[0025] 5-Pre-evaporator;

[0026] 61 - First valve; 62 - Second valve;

[0027] 71-First check valve device; 72-Second check valve device;

[0028] 81-First temperature detection unit; 82-Second temperature detection unit;

[0029] 9-Throttle valve;

[0030] 10 - Intermediate heat exchanger;

[0031] 11-Battery cooler. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Please refer to Figure 1 , Figure 1 This is a schematic block diagram illustrating the connection of the air conditioning system in an embodiment of the present invention.

[0034] In this embodiment, the air conditioning system includes a compressor 1, a liquid receiver 3, an outdoor condenser 2, an indoor condenser 4, a front evaporator 5, and a battery cooler 11. It also includes a first valve 61 and a second valve 62. The first valve 61 controls the on / off connection between the compressor 1 outlet and the outdoor condenser 2 inlet, and the second valve 62 controls the on / off connection between the compressor 1 outlet and the indoor condenser 4. The first valve 61 and the second valve 62 can be on / off valves, for example... Figure 1 The valve shown is a ball valve, but it could also be a solenoid valve with adjustable opening, as long as it can achieve on / off switching. There are no restrictions on the specific type.

[0035] The air conditioning system includes heating mode and cooling mode. The working cycle loops for the two modes are the cooling loop and the heating loop, respectively, as follows:

[0036] When the air conditioning system operates in cooling mode, compressor 1 discharges a high-temperature, high-pressure working medium, which enters the outdoor condenser 2 through the first valve 61. The outdoor condenser 2 is connected to one inlet of the receiver 3. The working medium flows out from the outlet of the receiver 3, which connects to a first branch and a second branch. The first branch connects to the inlet of the front evaporator 5, and the second branch connects to the inlet of the battery cooler 11. The working medium from the first branch flows out through the front evaporator 5, and the working medium from the second branch flows out through the battery cooler 11. Then, the working medium from both branches converges back to the compressor 1 inlet. In cooling mode, the working medium dissipates heat to the ambient air in the outdoor condenser 2 and absorbs heat in the front evaporator 5, causing the working medium passing through the front evaporator 5 to become overheated. The working medium from the second branch absorbs heat from the battery, thus cooling the battery.

[0037] When the air conditioning system is operating in heating mode, the high-temperature, high-pressure working medium discharged from compressor 1 enters the indoor condenser 4 through the second valve 62. The indoor condenser 4 can be connected to another inlet of the receiver 3. The outlet of the receiver 3 connects to the first and second branches mentioned above. Similarly, the working medium from both branches converges back to the inlet of compressor 1. When operating in the heating circuit, the working medium dissipates heat to the passenger compartment within the indoor condenser 4 and also absorbs heat from the front evaporator 5, causing the working medium passing through the front evaporator 5 to become overheated. The working medium from the second branch absorbs heat from the battery.

[0038] Please refer to Figure 2 , Figure 2This is a schematic diagram illustrating parameter changes in the air conditioning system control method provided in this embodiment of the invention. The curve corresponding to ECond RFV represents the opening and closing change curve of the first valve; the two increases in the curve indicate that the first valve is open. The curve corresponding to HCond RFV represents the opening and closing change curve of the second valve; it is not open at the beginning of the heating mode and remains open thereafter. The curve corresponding to SC RD represents the change curve of the subcooling degree of the indoor condenser. The curve corresponding to P Cmp suc represents the change curve of the compressor inlet pressure, and the curve corresponding to P Cmp disc represents the change curve of the compressor outlet pressure. P Cmpsuc is an abbreviation for compressor suction, and P Cmp disc is an abbreviation for compressor discharge.

[0039] In this embodiment, a detection element is set to detect the subcooling of the indoor condenser 4. The detection element specifically includes a first temperature detection unit 81 and a second temperature detection unit 82. The first temperature detection unit 81 is located between the outlet of the indoor condenser 4 and the inlet of the liquid receiver 3, and the second temperature detection unit 82 is located at the outlet of the liquid receiver 3 or in a pipeline connected to the outlet. The subcooling of the liquid receiver 3 is obtained by the detection values ​​of the first temperature detection unit 81 and the second temperature detection unit 82.

[0040] The air conditioning system is also equipped with a control unit. The control unit has a first subcooling preset value. The first temperature detection unit 81 and the second temperature detection unit 82 are connected to the control unit by signal, which can be wired or wireless, so as to output the detected temperature value to the control unit. When the air conditioning system is working in the heating circuit, the control unit determines whether the subcooling of the liquid receiver 3 is higher than the first subcooling preset value based on the detected temperature value. If it is higher than the first subcooling preset value, it indicates that the subcooling is too high. At the same time, the cooling circuit is also started, that is, the first valve 61 is opened. Then, part of the working medium flowing out from the compressor 1 will enter the outdoor condenser 2 and flow to the liquid receiver 3.

[0041] like Figure 1 As shown, since the heating circuit where the indoor condenser 4 is located is in operation during the heating mode, the pressure of the heating circuit is relatively high. Therefore, the pressure in the liquid receiver 3 is greater than the pressure of the newly opened refrigeration circuit. The working medium will not circulate in the refrigeration circuit. The working medium flowing out from the first valve 61 will be stored in the outdoor condenser 2 and the pipeline between the liquid receiver 3 and the compressor 1. This is equivalent to dispersing a certain amount of working medium to the upstream part of the liquid receiver 3 in the refrigeration circuit for storage by simultaneously opening the first valve 61. Generally, the capacity of the pipeline is limited, so the working medium is mainly stored in the outdoor condenser 2, thereby reducing the working medium entering the indoor condenser 4 in the heating circuit and reducing the subcooling of the liquid receiver 3. Figure 1In the middle, the liquid receiver 3 has two inlets, and the two inlets are respectively equipped with a first one-way valve device 71 and a second one-way valve device 72, so as to unidirectionally guide the outdoor condenser 2 to the liquid receiver 3 and unidirectionally guide the indoor condenser 4 to the liquid receiver 3. By setting the opening pressure of the one-way valve device, the storage capacity of the outdoor condenser 2 can also be adjusted.

[0042] In this way, when the capacity of the outdoor condenser 2 is greater than that of the indoor condenser 4, and the total working medium charge of the system is greater than the working requirements of the indoor condenser 4, the subcooling of the liquid receiver 3 is reduced by conditionally opening the refrigeration circuit in the heating mode, so that the system meets the requirements.

[0043] Specifically, in addition to the first subcooling preset value, the control unit can also set at least one subcooling preset value that decreases sequentially, and all of them are less than the first subcooling preset value. These can be defined in descending order as subcooling preset value one, subcooling preset value two, ..., subcooling preset value N, where N is greater than or equal to 1. For example... Figure 2 The aforementioned setting includes a first subcooling preset value that is less than the first subcooling preset value, wherein the first subcooling preset value and the first subcooling preset value respectively correspond to... Figure 2 Based on the values ​​A and B in the data, the control unit determines that the subcooling is higher than the first preset subcooling value and simultaneously activates the refrigeration circuit. Figure 2 As can be seen from the position corresponding to the dotted line in the middle, the value A corresponds to the opening state curve of the first valve 61. After the refrigeration circuit starts for the first predetermined time, the first valve 61 is closed, that is, the refrigeration circuit is closed, and only the heating circuit is opened. After the second predetermined time, the subcooling can be detected again. If the control unit determines that the subcooling at this time is higher than the preset subcooling value, it means that the subcooling has not decreased according to the expected downward trend. Figure 2 If the detected B value is higher than the preset subcooling value, the cooling circuit will continue to operate in heating mode for a third predetermined time to allow the subcooling to continue decreasing. The curve on the right corresponds to the B value and the start of the second cooling circuit. Figure 2 As can be seen, after the heating mode is turned on, the subcooling level rises sharply to its highest value, which corresponds to the first preset subcooling level mentioned above. After decreasing to a certain value, it stabilizes, and after decreasing again, the stable value corresponds to the required subcooling level, and no further adjustment is made. Figure 2 The C value represents the required subcooling level.

[0044] The specific values ​​of the first predetermined time, the second predetermined time, the third predetermined time, the first subcooling preset value, and the subcooling preset value can be set according to the actual needs of the system, for example, by experimental determination.

[0045] After setting the first subcooling preset value as the parameter for simultaneously starting the refrigeration circuit, at least one decreasing subcooling preset value can also be set. This allows for phased adjustment of the subcooling, enabling the judgment of the subcooling decreasing trend in an intermittent manner, and thus more quickly adjusting the subcooling to the desired optimal or best value. That is, setting one or more subcooling preset values ​​here aims to determine after a certain period whether the subcooling is decreasing as expected. If it is not decreasing, the refrigeration circuit continues to start, distributing the working medium to the refrigeration circuit. If it decreases to the required subcooling, only the heating mode can be activated. At this point, the excess working medium causing the excessive subcooling of the receiver 3 has been distributed to the refrigeration circuit, and the subcooling of the receiver 3 can be relatively stable. Figure 2 As shown, after the refrigeration circuit has been started twice, it is not necessary to simultaneously start the refrigeration circuit again to adjust the subcooling based on the first subcooling preset value. Of course, the change in subcooling can still be monitored in real time or intermittently. If the subcooling becomes too high again (i.e., exceeds the first subcooling preset value), the refrigeration circuit can be started again, and the working medium can continue to be dispersed according to the above process.

[0046] The step described above, where the refrigeration circuit is started and runs for a set time after the subcooling degree exceeds a first preset subcooling degree value, and then shut down, can be defined as step S1. It can be understood that at least one additional preset subcooling degree value is set below the first preset subcooling degree value. At this point, based on the comparison between the detected subcooling degree and the corresponding preset subcooling degree value, it is determined whether to execute step S1 again. The correspondence here means that after the first execution of step S1, it is compared with the first preset subcooling degree value; after the second execution of step S1, it is compared with the second preset subcooling degree value, and so on. Furthermore, the running time and shut-down time of the refrigeration circuit in step S1 can be different or the same; this solution does not impose any restrictions.

[0047] It is understandable that if the detected subcooling is higher than the first preset subcooling value and the refrigeration circuit is started for a set time, the refrigeration circuit can be directly shut down. For example, if experiments determine that the subcooling can reach the required value within a certain time after the refrigeration circuit is turned on, then multiple monitoring and cyclic adjustments of the subcooling decrease are unnecessary. Of course, setting the first or second preset subcooling value can better monitor and adjust the effect of subcooling decrease. Alternatively, the required subcooling value can be determined through experiments and simulations, and the subcooling can be acquired in real time. During the process of simultaneously turning on the refrigeration circuit, the subcooling value and the required value can be compared in real time until the subcooling decreases to the required value. However, compared to the first method, the intermittent adjustment is more conducive to the operation of the heating mode and makes it easier to store the working medium in the refrigeration circuit.

[0048] As a further technical solution, during the operation of the heating circuit, if the subcooling degree of the receiver 3 is detected to be too low, the second valve 62 can be closed to pause the heating mode, i.e., temporarily shut down the heating circuit. The pressure of the receiver 3 decreases, and the first valve 61 is opened to start the refrigeration circuit for a predetermined time. Due to the reduced pressure of the receiver 3, the working medium can circulate in the refrigeration circuit. The working medium stored in the refrigeration circuit upstream of the receiver 3 can return to the compressor 1. Then, the first valve 61 is closed and the second valve 62 is opened, so that the previously stored working medium can be redistributed to the indoor condenser 4 in the heating circuit after returning to the compressor 1, thereby increasing the distribution of working medium and improving the subcooling degree of the receiver 3. The predetermined time for the refrigeration circuit to open is the same as the time for the heating mode to close. This can be determined experimentally or by monitoring the change in the subcooling degree after the heating mode is restarted. If the subcooling degree is still too low, there may still be a certain amount of working medium stored. In this case, the refrigeration circuit can be restarted to ensure that more working medium flows back to the compressor 1.

[0049] Furthermore, in the above embodiment, before the heating circuit is activated, the cooling circuit can be activated first, while the heating circuit remains temporarily closed. That is, when heating is needed, the first valve 61 is opened, and the second valve 62 remains closed. Then, the high-low pressure ratio of the compressor 1 in the air conditioning system is detected. The high-low pressure ratio is the ratio of the outlet pressure to the inlet pressure of compressor 1. The control unit can set a preset value for the pressure ratio. When the detected pressure ratio reaches the preset value, the first valve 61 is closed, the second valve 62 is opened, and the heating mode is entered, followed by the aforementioned control process. By activating the heating circuit only after the preset pressure ratio value is reached during operation, the compressor 1 can be protected. Figure 2 In the process, the inlet pressure and outlet pressure of compressor 1 are initially equal. Then, the inlet pressure drops for a short period of time and then remains stable, while the outlet pressure rises for a period of time and then remains stable. In the refrigeration circuit, the inlet pressure reaches value a and the outlet pressure reaches value b. That is, after b / a reaches the preset value, the heating mode is turned on. The first dotted line on the left indicates that the heating circuit is turned on, where the b / a value is the specific pressure ratio preset value.

[0050] like Figure 1As shown, the air conditioning system also includes an intermediate heat exchanger 10, a front evaporator 5, and a battery cooler 11. The intermediate heat exchanger 10 includes a first inlet, a first outlet, a second inlet, and a second outlet. The outlet of the liquid receiver 3 is connected to the first inlet of the intermediate heat exchanger 10, the first outlet is connected to the inlet of the front evaporator 5, the outlet of the front evaporator 5 is connected to the second inlet, the second outlet is connected to the compressor 1, and the first outlet is connected to the battery cooler 11. Thus, the working medium flowing out of the outlet of the liquid receiver 3 is throttled by the expansion valve 9 and flows into the intermediate heat exchanger 10. The working medium flowing out of the front evaporator 5 also flows through the intermediate heat exchanger 10 and then to the compressor 1. Therefore, the working medium flowing out of the liquid receiver 3 can exchange heat with the working medium flowing out of the front evaporator 5 in the intermediate heat exchanger 10. After heat exchange, part of the working medium enters the battery cooler 11 to improve the heat exchange efficiency.

[0051] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A control method for an air conditioning system, the air conditioning system comprising a heating circuit and a cooling circuit, wherein the cooling circuit includes an outdoor condenser, the heating circuit includes an indoor condenser, the outdoor condenser having a capacity greater than the indoor condenser, the air conditioning system further comprising a liquid receiver having two inlets, the two inlets being equipped with one-way valves for unidirectional flow through the liquid receiver, the heating circuit being unidirectionally connected to the indoor condenser through one of the one-way valves, and the cooling circuit being unidirectionally connected to the outdoor condenser through the other one-way valve, characterized in that... The control method includes the following steps: When the heating circuit is running, the subcooling degree of the liquid receiver is detected. When the subcooling degree is higher than the first subcooling degree preset value, the cooling circuit is started at the same time.

2. The control method for the air conditioning system as described in claim 1, characterized in that, It also includes one of the following steps: S1: After the refrigeration circuit has been started for a set time, the refrigeration circuit is then turned off; S2: After the first execution of step S1, execute step S1 at least once at a predetermined interval; S3: After starting the refrigeration circuit, if the subcooling reaches the required value, the refrigeration circuit will be shut down.

3. The control method for the air conditioning system as described in claim 2, characterized in that, In step S2, at least one preset subcooling value is set in successive increments, and all of them are less than the first preset subcooling value. The detected subcooling is compared with the corresponding preset subcooling value according to the number of times step S1 is executed. If it is greater than the corresponding preset subcooling value, step S1 is executed again.

4. The control method for the air conditioning system as described in claim 1, characterized in that, When the heating circuit is running, the subcooling of the liquid receiver is detected. If the subcooling is lower than the second subcooling preset value, the heating circuit is temporarily shut down and the cooling circuit is started for a predetermined time. When the subcooling is not lower than the second subcooling preset value, the cooling circuit is shut down and the heating circuit is restarted.

5. The control method for an air conditioning system as described in any one of claims 1-4, characterized in that, Before starting the heating circuit, the pressure ratio of the high and low pressure of the compressor is detected. When the pressure ratio of the high and low pressure of the compressor is less than the preset pressure ratio value, the cooling circuit is started first. When the pressure ratio of the high and low pressure of the air conditioning system compressor reaches the preset pressure ratio value, the heating circuit is started and the cooling circuit is shut down.

6. An air conditioning system, comprising a heating circuit and a cooling circuit, wherein an outdoor condenser is provided in the cooling circuit, and an indoor condenser is provided in the heating circuit, wherein the capacity of the outdoor condenser is greater than the capacity of the indoor condenser, characterized in that, It also includes a liquid receiver with two inlets. The two inlets are equipped with one-way valves that allow one-way flow to the liquid receiver. The heating circuit is connected to the indoor condenser and the liquid receiver through one of the one-way valves, and the cooling circuit is connected to the outdoor condenser and the liquid receiver through the other one-way valve. It also includes a detection element for detecting the subcooling of the liquid reservoir, and a control unit connected to the detection element by a signal. The control unit has a first subcooling preset value stored in it. When the heating circuit is running, if the control unit determines that the detected subcooling is higher than the first subcooling preset value, it will start the cooling circuit. After the cooling circuit is started, if the detected subcooling reaches the required value, the cooling circuit will be shut down.

7. The air conditioning system as described in claim 6, characterized in that, The detection element includes a first temperature detection unit and a second temperature detection unit. The first temperature detection unit is located between the indoor condenser and the liquid receiver, and the second temperature detection unit is located at the outlet of the liquid receiver or in a pipeline connected to the outlet. The subcooling is obtained by the temperature difference of the refrigerant at the location of the first temperature detection unit and the location of the second temperature detection unit.

8. The air conditioning system as described in claim 6, characterized in that, It also includes an intermediate heat exchanger, a front evaporator, and a battery cooler. The intermediate heat exchanger includes a first inlet, a first outlet, a second inlet, and a second outlet. The outlet of the liquid receiver is connected to the first inlet of the intermediate heat exchanger, the first outlet is connected to the inlet of the front evaporator, the outlet of the front evaporator is connected to the second inlet, the second outlet is connected to the compressor, and the first outlet is connected to the battery cooler.

Images