Air conditioning system

Abstract

The application provides an air conditioning system, comprising a first heating circuit and a second heating circuit which are arranged in parallel; in the first heating circuit, refrigerant at the outlet of a compressor is sequentially sent to a first indoor heat exchanger, a first throttling valve, an outdoor heat exchanger and a gas-liquid separator and then returned to the compressor; in the second heating circuit, refrigerant at the outlet of the compressor is sequentially sent to the first indoor heat exchanger, a second throttling valve, a second indoor heat exchanger, mixed with refrigerant at the outlet of the outdoor heat exchanger and then sent to the gas-liquid separator and then returned to the compressor; a control device is configured to perform the following steps: a dehumidification step of controlling the opening degree of the second throttling valve to be reduced so that the second indoor heat exchanger functions as an evaporator to absorb moisture; a defrosting step of controlling the opening degree of the first throttling valve to be increased so that the outdoor heat exchanger functions as a condenser to release heat; and controlling the opening degree of the second throttling valve to be reduced so that the second indoor heat exchanger functions as an evaporator. The air conditioning system of the application can simultaneously and independently perform defrosting and dehumidification, and has strong applicability.

Description

Technical Field

[0001] This invention relates to the field of air conditioning, specifically to air conditioning systems. Background Technology

[0002] Transcritical CO2 automotive heat pump air conditioning systems can be used for heating in winter and cooling in summer. In winter, when temperatures are low, the windshield is cold and the humidity inside the car is high, easily causing fogging on the windshield. Thick fog can severely impair the driver's and passengers' visibility and safety, and the high humidity can also reduce human comfort. In addition, the outdoor heat exchanger is in a low-temperature environment, making it prone to frost formation, which deteriorates its operation and affects the performance of the heat pump system.

[0003] When operating in heating mode, if the windshield fogs up and the outdoor heat exchanger frosts up simultaneously, it is usually necessary to switch to cooling mode. This forces the indoor heat exchanger to act as an evaporator to dehumidify the vehicle interior, while the outdoor heat exchanger acts as a condenser to release heat and defrost, impacting the user experience. Furthermore, automotive heat pumps operate in harsher environments than household hot water heat pumps, frequently subjected to vibration, and four-way ball valves are prone to failure under such conditions. Summary of the Invention

[0004] To address the above problems, the present invention provides an air conditioning system that at least solves some of the aforementioned problems.

[0005] This invention provides an air conditioning system, including a parallel heating circuit, comprising a first heating circuit and a second heating circuit arranged in parallel; in the first heating circuit, refrigerant from the compressor outlet sequentially passes through a first indoor heat exchanger, a first throttle valve, an outdoor heat exchanger, and a gas-liquid separator before returning to the compressor; in the second heating circuit, refrigerant from the compressor outlet sequentially passes through a first indoor heat exchanger, a second throttle valve, and a second indoor heat exchanger, mixes with refrigerant from the outdoor heat exchanger outlet, and then returns to the compressor via a gas-liquid separator; a control device is configured to perform the following steps: a dehumidification step: controlling and reducing the opening of the second throttle valve, causing the second indoor heat exchanger to act as an evaporator to absorb moisture; a defrosting step: controlling and increasing the opening of the first throttle valve, causing the outdoor heat exchanger to act as a condenser to release heat; controlling and decreasing the opening of the second throttle valve, causing the second indoor heat exchanger to act as an evaporator.

[0006] According to this technical solution, the outdoor heat exchanger and the second indoor heat exchanger are connected in parallel. When the parallel heating circuit is running, the outdoor heat exchanger in the first heating circuit and the second indoor heat exchanger in the second heating circuit can operate independently. That is, compared to the case where the second indoor heat exchanger and the outdoor heat exchanger are connected in series and the temperature of the outdoor heat exchanger is always lower than the temperature of the second indoor heat exchanger, by controlling the amount of refrigerant entering the second indoor heat exchanger and the outdoor heat exchanger, the temperature of the outdoor heat exchanger can be made higher than the temperature of the second indoor heat exchanger. By controlling the opening of the first throttle valve corresponding to the outdoor heat exchanger, the outdoor heat exchanger can be used as a condenser to release heat and defrost; while the second indoor heat exchanger is at a lower operating temperature, which is beneficial for dehumidification.

[0007] In addition, during defrosting, the second indoor heat exchanger acts as an evaporator. The gaseous refrigerant at its outlet mixes with the liquid refrigerant at the outlet of the outdoor heat exchanger, which reduces the content of liquid refrigerant components in the mixed refrigerant, ensuring the amount of refrigerant in the heating cycle and ensuring the heating effect. By controlling the opening of the second throttle valve corresponding to the second indoor heat exchanger, the second indoor heat exchanger acts as an evaporator to draw in the surrounding air with high humidity. The moisture in the air condenses into water when it encounters the cold air, thus achieving dehumidification. Defrosting and dehumidification can be carried out simultaneously.

[0008] In an optional technical solution of the present invention, the system further includes: a series heating circuit, comprising: a first switching valve disposed between a first indoor heat exchanger and a first throttling valve; a second switching valve disposed between a second indoor heat exchanger and an outdoor heat exchanger; and a third switching valve, one end of which is connected between the second indoor heat exchanger and the second switching valve, and the other end of which is connected between the first switching valve and the first throttling valve; in the series heating circuit, the first switching valve is open, the second switching valve is open, and the third switching valve is open.

[0009] According to this technical solution, the air conditioning system includes a series heating circuit and a parallel heating circuit. By selecting different heating circuits under different operating conditions, the flexibility of the air conditioning system is improved.

[0010] In an optional technical solution of the present invention, a refrigeration circuit is further included, comprising: a fourth switching valve disposed between the compressor and the first indoor heat exchanger; a fifth switching valve disposed between the compressor and the outdoor heat exchanger; a sixth switching valve disposed between the outdoor heat exchanger and the inlet of the gas-liquid separator; and a seventh switching valve, with its two ends respectively connected between the first indoor heat exchanger and the fourth switching valve, and between the gas-liquid separator and the sixth switching valve; in the refrigeration circuit, the fifth switching valve is open, the first switching valve is closed, the third switching valve is open, the second switching valve is closed, the seventh switching valve is open, the sixth switching valve is closed, and the fourth switching valve is closed.

[0011] According to this technical solution, the air conditioning system also includes a refrigeration circuit, which can meet the user's refrigeration needs and improve the user experience; and through the setting of the switching valve, the switching between refrigeration and heating can be realized without the need for switching through the four-way valve, which has better stability and overcomes the defect of the four-way valve being prone to vibration failure during operation.

[0012] In an optional technical solution of the present invention, the system further includes: a temperature detection module for detecting outdoor ambient temperature; a humidity detection module for detecting outdoor relative humidity; a data processing module for calculating outdoor dew point temperature based on outdoor ambient temperature and outdoor relative humidity; and a control device further configured to: control the air conditioning system to operate a refrigeration circuit when the outdoor ambient temperature is greater than a first preset temperature; control the air conditioning system to operate a parallel heating circuit when the outdoor ambient temperature is less than a second preset temperature and the outdoor dew point temperature is less than a third preset temperature; and control the air conditioning system to operate a series heating circuit when the outdoor ambient temperature is less than the second preset temperature and the outdoor dew point temperature is not less than the third preset temperature; wherein the first preset temperature, the second preset temperature, and the third preset temperature decrease sequentially.

[0013] According to this technical solution, different operating modes can be selected based on different outdoor ambient temperatures, which helps to ensure the reliable operation of the air conditioning system; different heating circuits can be selected based on different outdoor dew point temperatures, which can overcome the defects of reduced heating effect caused by simultaneous defrosting and / or dehumidification during the heating process, and improve the user experience.

[0014] In the optional technical solution of the present invention, it further includes: an indoor relative humidity acquisition module for acquiring indoor relative humidity; the control device is configured to: when the parallel heating circuit is running, if the indoor relative humidity is greater than a first humidity threshold, control the air conditioning system to perform a dehumidification step and a defrosting step; when the parallel heating circuit is running, if the indoor relative humidity is not greater than the first humidity threshold, control the air conditioning system to perform a defrosting step.

[0015] According to this technical solution, the air conditioning system executes different control logics under different indoor relative humidity conditions, thereby improving the reliability of the air conditioning system operation.

[0016] In an optional technical solution of the present invention, the control device is further configured to: when the series heating circuit is running, if the indoor relative humidity is greater than the second humidity threshold, control the opening of the second throttle valve to decrease, so that the second indoor heat exchanger acts as an evaporator; when the series heating circuit is running, if the indoor relative humidity is not greater than the second humidity threshold, control the second throttle valve to be fully open.

[0017] According to the technical solution, when the indoor relative humidity is greater than the second humidity threshold, the second indoor heat exchanger acts as an evaporator to dehumidify the surrounding air; when the indoor relative humidity is not greater than the second humidity threshold, the second throttle valve is fully open, and the second indoor heat exchanger is used as a condenser, and the heat it releases can heat the surrounding air, ensuring or improving the heating performance of the air conditioner.

[0018] In an optional technical solution of the present invention, a fan is also included, which controls the airflow from the second indoor heat exchanger to the first indoor heat exchanger when the fan is running.

[0019] According to this technical solution, the second indoor heat exchanger is downstream of the first indoor heat exchanger. The temperature of the second indoor heat exchanger is lower than that of the first. Air first passes through the second indoor heat exchanger for cooling and dehumidification or preliminary heating, and then passes through the first indoor heat exchanger for further heating, thus increasing the heat exchange capacity. Specifically, in series heating operation and when the indoor relative humidity is greater than a second humidity threshold, by controlling the airflow from the second indoor heat exchanger to the first indoor heat exchanger, the air first passes through the second indoor heat exchanger for cooling and dehumidification, and then passes through the first indoor heat exchanger for heating, thus increasing the heat exchange capacity and achieving the dehumidification and heating function. In series heating operation and when the indoor relative humidity is not greater than the second humidity threshold, the second throttle valve is fully opened, and the first and second indoor heat exchangers operate as condensers under the same pressure. Air first passes through the second indoor heat exchanger for initial heating, and then passes through the first indoor heat exchanger for further heating, thus increasing the heat exchange capacity and achieving a powerful heating function. When operating in parallel heating and dehumidification mode, the air is first cooled and dehumidified by the second indoor heat exchanger, and then heated by the first indoor heat exchanger. This also increases the heat exchange capacity and improves the dehumidification and heating effects.

[0020] In an optional technical solution of the present invention, the refrigerant used in the air conditioning system is carbon dioxide.

[0021] According to this technical solution, the critical temperature of the refrigerant has a significant impact on the efficiency and performance of the air conditioning system. Below the critical temperature, the refrigerant forms saturated vapor in the compressor, then cools into a liquid state through the condenser, and finally enters the evaporator through the expansion valve to evaporate, thereby cooling the air or objects. Above the critical temperature, the refrigerant cannot form saturated vapor and cannot be compressed, causing the refrigeration system to malfunction. CO2 has a critical point of 30.98℃ and a pressure of 7.38MPa, making its operating conditions relatively easy to achieve. Furthermore, it is non-toxic, non-flammable, physically stable, and has good flow and heat transfer characteristics, making it an excellent alternative to R134a refrigerant for electric vehicle air conditioning and suitable for widespread application in electric vehicle thermal management systems.

[0022] In an optional embodiment of the present invention, the control device is further configured to: after the defrosting step is completed, adjust the opening of the first throttle valve so that the operating temperature of the outdoor heat exchanger is higher than the outdoor dew point temperature, thereby preventing the outdoor heat exchanger from frosting again. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the air conditioning system in an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the refrigerant flow direction in the parallel heating mode of the air conditioning system according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the refrigerant flow direction in the series heating mode of the air conditioning system in an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the refrigerant flow direction in the cooling mode of the air conditioning system according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the control method of the air conditioning system in an embodiment of the present invention.

[0028] Figure label:

[0029] Compressor 1; First indoor heat exchanger 21; Second indoor heat exchanger 22; First throttle valve 31; Second throttle valve 32; Outdoor heat exchanger 4; Gas-liquid separator 5; First switching valve 61; Second switching valve 62; Third switching valve 63; Fourth switching valve 64; Fifth switching valve 65; Sixth switching valve 66; Seventh switching valve 67. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] like Figure 1 As shown, this embodiment provides an air conditioning system, including a compressor 1, a first indoor heat exchanger 21, a first throttling valve 31, an outdoor heat exchanger 4, and a gas-liquid separator 5 connected in sequence to form a closed-loop circuit. It also includes a parallel branch connected in parallel with both ends of the first indoor heat exchanger 21 and the outdoor heat exchanger 4, and a second throttling valve 32 and a second indoor heat exchanger 22 are provided on the parallel branch. Further, the air conditioning system also includes a first switching valve 61, a second switching valve 62, a third switching valve 63, a fourth switching valve 64, a fifth switching valve 65, a sixth switching valve 66, and a seventh switching valve 67.

[0032] in,

[0033] The first switching valve 61 is located between the first indoor heat exchanger 21 and the first throttle valve 31; the second switching valve 62 is located between the second indoor heat exchanger 22 and the outdoor heat exchanger 4; one end of the third switching valve 63 is connected between the second indoor heat exchanger 22 and the second switching valve 62, and the other end of the third switching valve 63 is connected between the first switching valve 61 and the first throttle valve 31; the fourth switching valve 64 is located between the compressor 1 and the first indoor heat exchanger 21; the fifth switching valve 65 is located between the compressor 1 and the outdoor heat exchanger 4; the sixth switching valve 66 is located between the outdoor heat exchanger 4 and the inlet of the gas-liquid separator 5; and the two ends of the seventh switching valve 67 are respectively connected between the first indoor heat exchanger 21 and the fourth switching valve 64, and between the gas-liquid separator 5 and the sixth switching valve 66.

[0034] In this embodiment, such as Figure 2 As shown, the control valves 64, 65, 67, 61, 66, 63, and 62 open, respectively, and the air conditioning system operates a parallel heating circuit. The parallel heating circuit includes a first heating circuit and a second heating circuit connected in parallel. In the first heating circuit, the refrigerant from the compressor 1 outlet passes through the first indoor heat exchanger 21, the first throttle valve 31, the outdoor heat exchanger 4, and the gas-liquid separator 5 before returning to the compressor 1. In the second heating circuit, the refrigerant from the compressor 1 outlet passes through the first indoor heat exchanger 21, the second throttle valve 32, the second indoor heat exchanger 22, mixes with the refrigerant from the outdoor heat exchanger 4 outlet, and then returns to the compressor 1 via the gas-liquid separator 5.

[0035] The air conditioning system also includes a control device (not shown in the figure) configured to perform the following steps: Dehumidification step: controlling to reduce the opening of the second throttle valve 32 in the second heating circuit, so that the second indoor heat exchanger 22 acts as an evaporator to absorb moisture; Defrosting step: controlling to increase the opening of the first throttle valve 31 in the first heating circuit, so that the outdoor heat exchanger 4 acts as a condenser to release heat; controlling to reduce the opening of the second throttle valve 32, so that the second indoor heat exchanger 22 acts as an evaporator.

[0036] In this way, the outdoor heat exchanger 4 and the second indoor heat exchanger 22 are connected in parallel. When the parallel heating circuit is running, the outdoor heat exchanger 4 in the first heating circuit and the second indoor heat exchanger 22 in the second heating circuit can operate independently. That is, compared to the case where the second indoor heat exchanger 22 and the outdoor heat exchanger 4 are connected in series and the temperature of the outdoor heat exchanger 4 is always lower than the temperature of the second indoor heat exchanger 22, by controlling the amount of refrigerant entering the second indoor heat exchanger 22 and the outdoor heat exchanger 4, the temperature of the outdoor heat exchanger 4 can be made higher than the temperature of the second indoor heat exchanger 22. By controlling the opening of the first throttle valve 31 corresponding to the outdoor heat exchanger 4, the temperature of the refrigerant in the outdoor heat exchanger 4 can be made higher than the outdoor ambient temperature, that is, the outdoor heat exchanger 4 can be used as a condenser to release heat and defrost; while the second indoor heat exchanger 22 is at a lower operating temperature, which is beneficial for dehumidification.

[0037] Furthermore, during defrosting, the second indoor heat exchanger 22 acts as an evaporator. The gaseous refrigerant at its outlet mixes with the liquid refrigerant at the outlet of the outdoor heat exchanger 4, reducing the content of liquid refrigerant components in the mixed refrigerant, ensuring the amount of refrigerant in the heating cycle, and guaranteeing the heating effect. In some embodiments, the heat release of the first indoor heat exchanger 21 can be reduced, resulting in a higher temperature for the refrigerant entering the outdoor heat exchanger 4 from the first indoor heat exchanger 21, thus defrosting the outdoor heat exchanger. Additionally, the refrigerant at the outlet of the outdoor heat exchanger 4 contains a higher proportion of gaseous refrigerant, ensuring the amount of refrigerant in the heating cycle. Moreover, by controlling the opening of the second throttle valve 32 corresponding to the second indoor heat exchanger 22, the refrigerant temperature inside the second indoor heat exchanger 22 is lower than the outdoor ambient temperature. The second indoor heat exchanger 22 can then act as an evaporator, drawing in humid air from the surrounding environment. The moisture in the air condenses into water upon cooling, achieving dehumidification, thus enabling simultaneous defrosting and dehumidification.

[0038] In this embodiment, the control device can be an integrated circuit chip with signal processing capabilities. The aforementioned control device can be a general-purpose processor, including a central processing unit (CPU), or a microcontroller, microcontroller unit (MCU), complex programmable logic device (CPLD), field-programmable gate array (FPGA), application-specific integrated circuit (ASIC), embedded ARM, etc. The controller can implement or execute the methods, steps, and logic block diagrams disclosed in this embodiment of the invention.

[0039] In a preferred embodiment of the present invention, such as Figure 3 As shown, the control valves are as follows: fourth switch valve 64 is open, fifth switch valve 65 is closed, seventh switch valve 67 is closed, first switch valve 61 is closed, third switch valve 63 is open, sixth switch valve 66 is open, and second switch valve 62 is closed. The first indoor heat exchanger 21 and the second indoor heat exchanger 22 operate in series, forming a series heating circuit. In this circuit, the refrigerant passes sequentially through compressor 1, first indoor heat exchanger 21, second throttle valve 32, second indoor heat exchanger 22, first throttle valve 31, outdoor heat exchanger 4, and gas-liquid separator 5 before returning to the compressor. The air conditioning system includes both series and parallel heating circuits. By selecting different heating circuits under different operating conditions, the flexibility of the air conditioning system is improved.

[0040] In some implementations, such as Figure 4 As shown, the fifth switch valve 65 is opened, the fourth switch valve 64 is closed, the first switch valve 61 is closed, the third switch valve 63 is opened, the second switch valve 62 is closed, the seventh switch valve 67 is opened, and the sixth switch valve 66 is closed. This allows the air conditioning system to operate in the refrigeration circuit, which can meet the user's cooling needs and improve the user experience. Furthermore, the switch valve configuration allows for switching between cooling and heating without the need for a four-way valve, resulting in better stability and overcoming the defect of the four-way valve being prone to vibration failure during operation. During refrigeration operation, the second throttle valve 62 remains fully open, and the air is cooled by passing through the first and second indoor heat exchangers 21 and 22.

[0041] In a preferred embodiment of the present invention, it further includes: a temperature detection module (not shown in the figure) for detecting the outdoor ambient temperature; a humidity detection module (not shown in the figure) for detecting the outdoor relative humidity; and a data processing module (not shown in the figure) for calculating the outdoor dew point temperature based on the outdoor ambient temperature and the outdoor relative humidity; as shown in the figure. Figure 5 As shown, the control device (not shown in the figure) is further configured to: control the air conditioning system to operate the refrigeration circuit when the outdoor ambient temperature is higher than the first preset temperature; control the air conditioning system to operate the parallel heating circuit when the outdoor ambient temperature is lower than the second preset temperature and the outdoor dew point temperature is lower than the third preset temperature; and control the air conditioning system to operate the series heating circuit when the outdoor ambient temperature is lower than the second preset temperature and the outdoor dew point temperature is not lower than the third preset temperature; wherein the first preset temperature, the second preset temperature, and the third preset temperature decrease sequentially. In this embodiment, the first preset temperature is 25°C, the second preset temperature is 15°C, and the third preset temperature is 0°C. In some embodiments, when the outdoor ambient temperature is between the first preset temperature and the second preset temperature, the outdoor ambient temperature is in a more comfortable temperature range, and the air conditioning system can be shut down.

[0042] Specifically, when the outdoor ambient temperature is lower than the second preset temperature and the outdoor dew point temperature is higher than 0°C, defrosting or anti-frost is not required, and a series heating mode is adopted.

[0043] When the outdoor ambient temperature is lower than the second preset temperature and the outdoor dew point temperature is below 0°C, the outdoor heat exchanger 4 may or may not be frosted. If the outdoor heat exchanger 4 is frosted, adjusting the opening of the first throttle valve 61 controls the refrigerant flowing through the outdoor heat exchanger 4 at a higher temperature and releases heat to the outside, thus defrosting the outdoor heat exchanger 4. If the outdoor heat exchanger 4 is not frosted, but the outdoor dew point temperature is below 0°C, adjusting the opening of the first throttle valve 61 ensures that the refrigerant pressure entering the outdoor heat exchanger 4 is above the refrigerant saturation pressure corresponding to the outdoor dew point temperature, preventing the outdoor heat exchanger 4 from frosting when absorbing heat from the air, i.e., preventing frosting.

[0044] This implementation method selects different operating modes according to different outdoor ambient temperatures, which helps to ensure the reliable operation of the air conditioning system. It also selects different heating circuits according to different outdoor dew point temperatures, which can adjust the operation of the air conditioning system according to actual working conditions and reduce the impact of simultaneous defrosting and / or dehumidification during the heating process on the heating effect, thereby improving the user experience.

[0045] In a preferred embodiment of the present invention, reference is made again. Figure 5 The air conditioning system also includes: an indoor relative humidity acquisition module (not shown in the figure) for acquiring indoor relative humidity; the control device is configured to: when the parallel heating loop is running, if the indoor relative humidity is greater than a first humidity threshold, control the air conditioning system to perform dehumidification and defrosting steps (including both defrosting and anti-frost); when the parallel heating loop is running, if the indoor relative humidity is not greater than the first humidity threshold, control the air conditioning system to perform a defrosting step. Specifically, the first humidity threshold is 60%.

[0046] In a preferred embodiment of the present invention, the control device is further configured to: when the series heating circuit is running, if the indoor relative humidity is greater than the second humidity threshold, control the opening of the second throttle valve 32 to decrease, so that the second indoor heat exchanger 22 acts as an evaporator; when the series heating circuit is running, if the indoor relative humidity is not greater than the second humidity threshold, control the second throttle valve 32 to be fully open.

[0047] In series heating mode, the second humidity threshold is 60%. When the indoor air humidity is greater than 60%, the opening of the second throttle valve 62 is reduced, and the second indoor heat exchanger 22 is used as an evaporator. The air is first cooled and dehumidified by passing through the second indoor heat exchanger 22, and then heated by passing through the first indoor heat exchanger 21 (under the action of the fan described below), thus achieving the dehumidification and heating function. When the indoor temperature is much lower than the set temperature, it is necessary to rapidly heat the indoor air. At this time, the second throttle valve 62 is fully opened, and the second indoor heat exchanger 22 and the first indoor heat exchanger 21 work as condensers under the same pressure. The air is first initially heated by passing through the second indoor heat exchanger 22, and then further heated by entering the first indoor heat exchanger 21, thus achieving the functions of powerful heating and rapid dehumidification.

[0048] In a preferred embodiment of the present invention, a fan (not shown in the figure) is also included, which controls the airflow from the second indoor heat exchanger 22 to the first indoor heat exchanger 21 when the fan is running.

[0049] Specifically, the second indoor heat exchanger 22 is downstream of the first indoor heat exchanger 21. The temperature of the second indoor heat exchanger 22 is lower than that of the first indoor heat exchanger 21. The air first passes through the second indoor heat exchanger 22 for cooling and dehumidification or preliminary heating, and then passes through the first indoor heat exchanger 21 for further heating, which can increase the heat exchange capacity. Specifically, when operating in series heating mode and the indoor relative humidity is greater than the second humidity threshold, by controlling the airflow from the second indoor heat exchanger 22 to the first indoor heat exchanger 21, the air first passes through the second indoor heat exchanger 22 for cooling and dehumidification, and then passes through the first indoor heat exchanger 21 for heating, which can increase the heat exchange capacity and achieve the dehumidification and heating function. When operating in series heating mode and the indoor relative humidity is not greater than the second humidity threshold, the second throttle valve 32 is fully opened, and the first indoor heat exchanger 21 and the second indoor heat exchanger 22 work as condensers under the same pressure. The air first passes through the second indoor heat exchanger 22 for preliminary heating, and then passes through the first indoor heat exchanger 21 for further heating, which can increase the heat exchange capacity and achieve the powerful heating function. During parallel heating and dehumidification operation, the air is first cooled and dehumidified by the second indoor heat exchanger 22, and then heated by the first indoor heat exchanger 21. This can also increase the heat exchange capacity and improve the dehumidification and heating effects.

[0050] The critical temperature of a refrigerant has a significant impact on the efficiency and performance of an air conditioning system. Below the critical temperature, the refrigerant forms saturated vapor in compressor 1, then cools into a liquid state through the condenser, and finally enters the evaporator through the expansion valve to evaporate, thereby cooling the air or object. Above the critical temperature, the refrigerant cannot form saturated vapor and cannot be compressed, causing the refrigeration system to malfunction. In a preferred embodiment of the present invention, the refrigerant used in the air conditioning system is carbon dioxide. CO2 has a critical point of 30.98°C and a pressure of 7.38 MPa, making its operating conditions relatively easy to achieve. It is also non-toxic, non-flammable, physically stable, and has good flow and heat transfer characteristics, making it an excellent alternative to R134a refrigerant for electric vehicle air conditioning and suitable for widespread application in electric vehicle thermal management systems. In some embodiments, the refrigerant is not limited to carbon dioxide listed in this embodiment; it can also be Freon or other refrigerants.

[0051] The air conditioning system provided in this embodiment can operate in different modes, including cooling mode, series heating mode, and parallel heating mode, and can realize functions such as cooling, powerful heating, dehumidification heating, defrosting and dehumidification heating, and anti-frost dehumidification heating. The parallel heating mode of this embodiment allows the defrosting heat exchanger (outdoor heat exchanger 4) and the dehumidification heat exchanger (second indoor heat exchanger 22) to operate independently at different temperatures, so that the defrosting temperature and dehumidification temperature do not interfere with each other, and can adapt to more operating environments; the air conditioning system provided in this embodiment does not use a four-way reversing valve, avoiding the problem of its easy failure in vibration environments.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An air conditioning system, characterized in that, include: Parallel heating circuits include a first heating circuit and a second heating circuit connected in parallel. In the first heating circuit, the refrigerant from the compressor outlet passes sequentially through the first indoor heat exchanger, the first throttle valve, the outdoor heat exchanger, and the gas-liquid separator back to the compressor. In the second heating circuit, the refrigerant from the compressor outlet passes sequentially through the first indoor heat exchanger, the second throttle valve, the second indoor heat exchanger, and mixes with the refrigerant from the outdoor heat exchanger outlet before returning to the compressor via the gas-liquid separator. A series heating circuit, the series heating circuit comprising: The first switching valve is located between the first indoor heat exchanger and the first throttling valve; A second switching valve is located between the second indoor heat exchanger and the outdoor heat exchanger; The third switching valve has one end connected between the second indoor heat exchanger and the second switching valve, and the other end connected between the first switching valve and the first throttle valve; In the series heating circuit, the first switching valve is open, the second switching valve is open, and the third switching valve is open; The control device is configured to perform the following steps: Dehumidification steps: Control and reduce the opening of the second throttle valve so that the second indoor heat exchanger acts as an evaporator to absorb moisture; Defrosting steps: Control the opening of the first throttle valve to increase, so that the outdoor heat exchanger acts as a condenser to release heat; control the opening of the second throttle valve to decrease, so that the second indoor heat exchanger acts as an evaporator; The control device is also configured as follows: When the parallel heating circuit is running, if the indoor relative humidity is greater than the first humidity threshold, the air conditioning system is controlled to perform the dehumidification step and the defrosting step. When the parallel heating circuit is running, if the indoor relative humidity is not greater than the first humidity threshold, the air conditioning system is controlled to perform the defrosting step. When the series heating circuit is running, if the indoor relative humidity is greater than the second humidity threshold, the opening of the second throttle valve is reduced, so that the second indoor heat exchanger acts as an evaporator. When the series heating circuit is running, if the indoor relative humidity is not greater than the second humidity threshold, the second throttle valve is controlled to be fully open.

2. The air conditioning system according to claim 1, characterized in that, Also includes: Refrigeration circuit, the refrigeration circuit comprising: The fourth switching valve is located between the compressor and the first indoor heat exchanger; The fifth switching valve is located between the compressor and the outdoor heat exchanger; The sixth switching valve is located between the inlet of the outdoor heat exchanger and the gas-liquid separator; The seventh switch valve is connected at both ends between the first indoor heat exchanger and the fourth switch valve, and between the gas-liquid separator and the sixth switch valve, respectively. In the refrigeration circuit, the fifth switching valve is open, the first switching valve is open, the third switching valve is open, the second switching valve is open, the seventh switching valve is open, the sixth switching valve is closed, and the fourth switching valve is open.

3. The air conditioning system according to claim 2, characterized in that, Also includes: Temperature detection module, used to detect outdoor ambient temperature; Humidity detection module, used to detect outdoor relative humidity; The data processing module is used to calculate the outdoor dew point temperature based on the outdoor ambient temperature and the outdoor relative humidity. The control device is also configured as follows: When the outdoor ambient temperature is greater than the first preset temperature, the air conditioning system is controlled to operate the refrigeration circuit; When the outdoor ambient temperature is lower than the second preset temperature and the outdoor dew point temperature is lower than the third preset temperature, the air conditioning system is controlled to operate the parallel heating circuit. When the outdoor ambient temperature is lower than the second preset temperature and the outdoor dew point temperature is not lower than the third preset temperature, the air conditioning system is controlled to operate the series heating circuit; wherein the first preset temperature, the second preset temperature and the third preset temperature decrease sequentially.

4. The air conditioning system according to claim 3, characterized in that, Also includes: The indoor relative humidity acquisition module is used to acquire indoor relative humidity.

5. The air conditioning system according to claim 1, characterized in that, It also includes a fan, which, when in operation, controls the airflow from the second indoor heat exchanger to the first indoor heat exchanger.

6. The air conditioning system according to any one of claims 1 to 5, characterized in that, The air conditioning system uses carbon dioxide as the refrigerant.

7. The air conditioning system according to claim 1, characterized in that, The control device is also configured to: After the defrosting step is completed, the opening of the first throttle valve is adjusted so that the operating temperature of the outdoor heat exchanger is higher than the outdoor dew point temperature.

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