Ejector synergistic CO2 heat pump air conditioning system for new energy automobile and control method

Abstract

The invention discloses an ejector synergistic CO2 heat pump air-conditioning system for a new energy automobile. The ejector synergistic CO2 heat pump air-conditioning system comprises an air-conditioning module and an air-conditioning box module. The air conditioner module is composed of a compressor, an automobile outer side draught fan, an automobile outer heat exchanger, an automobile inner main heat exchanger, an automobile inner auxiliary heat exchanger, a heat regenerator, a gas-liquid separator, an ejector, an electronic expansion valve, a first four-way reversing valve, a second four-way reversing valve and a three-way valve. The air conditioner box module is composed of an air conditioner box body, an air conditioner air door and an air conditioner draught fan. In addition, the invention also discloses six working modes and a control method of the system. According to the system, the ejector is introduced to recycle expansion work in the refrigerant throttling process, the high-temperature refrigeration performance and the low-temperature heating performance of the CO2 heat pump air conditioner can be effectively improved, and the system is simple in structural design and stable and reliable in operation.

Description

Technical Field

[0001] The present invention belongs to the field of new energy vehicles, and specifically relates to an ejector-enhanced CO2 heat pump air-conditioning system and a control method for new energy vehicles. Background Art

[0002] With the rapid development of the new energy vehicle industry, the problem of low-temperature attenuation of its endurance has become increasingly prominent. It is imperative to develop a more green, efficient and energy-saving vehicle thermal management system and heat pump air conditioner. Automobile heat pump air conditioners using traditional working fluids such as R134a have insufficient heating capacity in low-temperature environments and often need to rely on electric heating devices for auxiliary heating, which leads to a significant increase in energy consumption and reduces the vehicle's cruising range. The natural working fluid CO2 is non-toxic and non-flammable, green and environmentally friendly, has good low-temperature performance, and excellent heat transfer and flow characteristics. It can be used in automobile heat pump air conditioners to significantly improve the low-temperature attenuation problem of its heating performance. However, due to the high-pressure characteristics of the CO2 heat pump air conditioning system, there are a large number of irreversible losses in the refrigerant throttling process. How to reduce its throttling loss has become an effective technical route to improve system performance. As a simple and low-cost pressure recovery component, the ejector can increase the compressor suction pressure and reduce throttling losses by recovering the expansion work of the refrigerant in the throttling process, thereby effectively improving system performance. Based on this direction, this application proposes an ejector-enhanced CO2 heat pump air-conditioning system for new energy vehicles, and provides multiple working modes, thereby significantly improving the high-temperature cooling and low-temperature heating performance of the new energy vehicle heat pump air-conditioning, reducing the thermal management energy consumption of the whole vehicle, and improving the vehicle's endurance and market competitiveness. Summary of the invention

[0003] In order to solve the deficiencies of the prior art, the present invention aims to propose an ejector-enhanced CO2 heat pump air conditioning system for new energy vehicles and provide a control method thereof. The system can utilize an ejector to recover the expansion work of the refrigerant throttling process, thereby effectively improving the performance of the system. At the same time, in view of the problem that the use of a regenerator under certain working conditions may cause the performance of the CO2 heat pump air conditioning to decay, the present invention can realize the free switching of the operation mode with and without regenerator by setting a three-way valve and a bypass loop in the system, thereby ensuring the stable and efficient operation of the system.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an ejector-enhanced CO2 heat pump air-conditioning system for new energy vehicles, comprising an air-conditioning module and an air-conditioning box module.

[0005] The air conditioning module includes a compressor, the compressor outlet is connected to the inlet of an auxiliary heat exchanger in the vehicle, the outlet of the auxiliary heat exchanger in the vehicle is connected to the a port of the first four-way reversing valve, the b port of the first four-way reversing valve is connected to the inlet of the heat exchanger outside the vehicle, the outlet of the heat exchanger outside the vehicle is connected to the a port of the second four-way reversing valve, the b port of the second four-way reversing valve is connected to the hot fluid side inlet of the regenerator, the hot fluid side outlet of the regenerator is connected to the primary fluid inlet of the ejector, the secondary fluid inlet of the ejector is connected to the d port of the second four-way reversing valve, the c port of the second four-way reversing valve is connected to the outlet of the main heat exchanger in the vehicle, the inlet of the main heat exchanger in the vehicle is connected to the d port of the first four-way reversing valve, the c port of the first four-way reversing valve is connected to the outlet of the electronic expansion valve, the inlet of the electronic expansion valve is connected to the liquid outlet of the gas-liquid separator, the inlet of the gas-liquid separator is connected to the outlet of the ejector, the gas outlet of the gas-liquid separator is connected to the b port of the three-way valve, the a port of the three-way valve is connected to the cold fluid side inlet of the regenerator, and the cold fluid side outlet of the regenerator is connected to the compressor inlet and the c port of the three-way valve.

[0006] The air-conditioning box module includes an air-conditioning box body, an air-conditioning fan and an air-conditioning damper; wherein the front part of the air-conditioning box body is a single-channel structure, and the rear part is divided into an independent auxiliary heat exchanger channel and a bypass channel, the auxiliary heat exchanger channel and the bypass channel are parallel structures, and the inlet and outlet are connected together; the air-conditioning fan is arranged at the inlet of the air-conditioning box body, the in-vehicle main heat exchanger of the above-mentioned air-conditioning module is arranged at the rear side of the air-conditioning fan, the air-conditioning damper is installed at the inlet of the auxiliary heat exchanger channel and the bypass channel, and the in-vehicle auxiliary heat exchanger of the above-mentioned air-conditioning module is arranged in the auxiliary heat exchanger channel.

[0007] The external heat exchanger, the internal main heat exchanger and the internal auxiliary heat exchanger are fin-tube heat exchangers or parallel flow heat exchangers, and the external fan is installed on the surface of the external heat exchanger.

[0008] The regenerator is a counter-flow heat exchanger.

[0009] The first four-way reversing valve and the second four-way reversing valve realize switching between the first working mode and the second working mode by different internal conduction modes of the four connection ports; wherein, the first working mode is that port a and port b are internally connected, and port c and port d are internally connected; the second working mode is that port a and port d are internally connected, and port b and port c are internally connected.

[0010] The three-way valve realizes switching between the first working mode and the second working mode by different internal conduction modes of the three connection ports; wherein, in the first working mode, port a and port b are internally connected, and port b and port c are not connected; and in the second working mode, port b and port c are internally connected, and port a and port b are not connected.

[0011] The air-conditioning damper of the air-conditioning box realizes the switching between the first working mode and the second working mode by controlling the different air flow paths, wherein the first working mode is that the air-conditioning damper opens the auxiliary heat exchanger side channel and closes the bypass channel, and the air from the main heat exchanger in the vehicle all flows through the auxiliary heat exchanger in the vehicle; the second working mode is that the air-conditioning damper opens the bypass channel and closes the auxiliary heat exchanger side channel, and the air from the main heat exchanger in the vehicle all flows through the bypass channel.

[0012] The present invention also proposes a control method for the above-mentioned ejector-enhanced CO2 heat pump air-conditioning system for new energy vehicles. The system working modes include a cooling mode with heat recovery, a cooling mode without heat recovery, a heating mode with heat recovery, a heating mode without heat recovery, a defrosting mode and a defrosting mode. The system working mode is switched by controlling the first four-way reversing valve, the second four-way reversing valve, the three-way valve, the electronic expansion valve, the vehicle outer side fan, the air-conditioning damper and the air-conditioning fan. The specific implementation steps are: (1) Cooling mode with heat recovery: When the passenger compartment requests cooling and the system determines that heat recovery is beneficial, the system starts the cooling mode with heat recovery, the compressor starts, the first four-way reversing valve switches to the first working mode, the second four-way reversing valve switches to the first working mode, the three-way valve switches to the first working mode, the air conditioning damper switches to the second working mode, the air conditioning fan starts, the vehicle outer fan starts, and the electronic expansion valve opens and automatically adjusts the opening according to the system operating conditions; (2) Non-regenerative cooling mode: When the passenger compartment requests cooling and the system determines that the regenerative cooling is harmful, the system starts the non-regenerative cooling mode, the compressor starts, the first four-way reversing valve switches to the first working mode, the second four-way reversing valve switches to the first working mode, the three-way valve switches to the second working mode, the air conditioning damper switches to the second working mode, the air conditioning fan starts, the vehicle outer side fan starts, and the electronic expansion valve opens and automatically adjusts the opening according to the system operating conditions; (3) Heating mode with regenerative heating: When the passenger compartment requests heating and the system determines that regenerative heating is beneficial, the system starts the heating mode with regenerative heating, the compressor starts, the first four-way reversing valve switches to the second working mode, the second four-way reversing valve switches to the second working mode, the three-way valve switches to the first working mode, the air conditioning damper switches to the first working mode, the air conditioning fan starts, the vehicle outer side fan starts, and the electronic expansion valve opens and automatically adjusts the opening according to the system operating conditions; (4) Non-regenerative heating mode: When the passenger compartment requests heating and the system determines that regenerative heating is harmful, the system starts the non-regenerative heating mode, the compressor starts, the first four-way reversing valve switches to the second working mode, the second four-way reversing valve switches to the second working mode, the three-way valve switches to the second working mode, the air conditioning damper switches to the first working mode, the air conditioning fan starts, the vehicle outer side fan starts, and the electronic expansion valve starts and automatically adjusts the opening according to the system operating conditions; (5) Demisting mode: When the passenger compartment requests demisting, the system starts the demisting mode, the compressor starts, the first four-way reversing valve switches to the first working mode, the second four-way reversing valve switches to the first working mode, the three-way valve switches to the first working mode, the air conditioning damper switches to the first working mode, the air conditioning fan starts, the vehicle outer fan is turned off, and the electronic expansion valve opens and automatically adjusts the opening according to the system operating conditions; (6) Defrost mode: When the external heat exchanger needs to be defrosted, the system starts the defrost mode, the compressor starts, the first four-way reversing valve switches to the first working mode, the second four-way reversing valve switches to the first working mode, the three-way valve switches to the first working mode, the air conditioning damper switches to the second working mode, the air conditioning fan turns off, the external fan turns off, and the electronic expansion valve turns on and maintains the maximum opening;

[0013] The ejector-enhanced CO2 heat pump air conditioning system and control method for new energy vehicles provided by the present invention have the following beneficial effects compared with the prior art: (1) The system can use the ejector to recover the expansion work of the refrigerant throttling process and reduce throttling losses, which has obvious performance advantages over conventional CO2 heat pump air conditioners; (2) The system uses two four-way reversing valves to control the refrigerant flow direction, realizing free switching among the four working modes of cooling, heating, defogger and defrost. Compared with the conventional multi-solenoid valve solution, it reduces the system complexity and improves the operation reliability; (3) The system can realize real-time switching between the operating modes with and without heat regeneration, avoiding the problem of system performance degradation caused by the use of heat regenerators under certain working conditions, thus ensuring the stable and efficient operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the present invention. The air conditioning module includes: 101-compressor, 102-in-vehicle auxiliary heat exchanger, 103-in-vehicle main heat exchanger, 104-second four-way reversing valve, 105-out-vehicle heat exchanger, 106-out-vehicle fan, 107-regenerator, 108-ejector, 109-three-way valve, 110-gas-liquid separator, 111-electronic expansion valve, 112-first four-way reversing valve; The air conditioning box module includes: 201-air conditioning box body, 202-auxiliary heat exchanger side channel, 203-bypass channel, 204-air conditioning damper, 205-air conditioning fan, and the arrow indicates the air flow direction inside the air conditioning box body. DETAILED DESCRIPTION

[0015] The present invention is illustrated by the following embodiments, but the present invention is not limited to the following embodiments. All implementation methods that meet the above-mentioned purposes are within the technical scope of the present invention. The present invention will be further described below in conjunction with the accompanying drawings.

[0016] An ejector-efficient CO2 heat pump air-conditioning system for new energy vehicles comprises an air-conditioning module and an air-conditioning box module.

[0017] The air conditioning module comprises a compressor 101, the outlet of the compressor 101 is connected to the inlet of an auxiliary heat exchanger 102 in the vehicle, the outlet of the auxiliary heat exchanger 102 in the vehicle is connected to the a port of the first four-way reversing valve 112, the b port of the first four-way reversing valve 112 is connected to the inlet of an external heat exchanger 105, the outlet of the external heat exchanger 105 is connected to the a port of the second four-way reversing valve 104, the b port of the second four-way reversing valve 104 is connected to the hot fluid side inlet of a regenerator 107, the hot fluid side outlet of the regenerator 107 is connected to the primary fluid inlet of an ejector 108, the secondary fluid inlet of the ejector 108 is connected to the d port of the second four-way reversing valve 104, and the The c port of the directional valve 104 is connected to the outlet of the in-vehicle main heat exchanger 103, the inlet of the in-vehicle main heat exchanger 103 is connected to the d port of the first four-way reversing valve 112, the c port of the first four-way reversing valve 112 is connected to the outlet of the electronic expansion valve 111, the inlet of the electronic expansion valve 111 is connected to the liquid outlet of the gas-liquid separator 110, the inlet of the gas-liquid separator 110 is connected to the outlet of the ejector 108, the gas outlet of the gas-liquid separator 110 is connected to the b port of the three-way valve 109, the a port of the three-way valve 109 is connected to the inlet of the cold fluid side of the regenerator 107, and the outlet of the cold fluid side of the regenerator 107 is connected to the inlet of the compressor 101 and the c port of the three-way valve 109.

[0018] The air-conditioning box module includes an air-conditioning box body 201, an air-conditioning fan 205 and an air-conditioning damper 204; wherein, the front part of the air-conditioning box body 201 is a single-channel structure, and the rear part is divided into an independent auxiliary heat exchanger channel 202 and a bypass channel 203, the auxiliary heat exchanger channel 202 and the bypass channel 203 are parallel structures, and the inlet and outlet are connected together; the air-conditioning fan 205 is arranged at the inlet of the air-conditioning box body 201, the in-vehicle main heat exchanger 103 of the above-mentioned air-conditioning module is arranged on the rear side of the air-conditioning fan 205, the air-conditioning damper 204 is installed at the inlet of the auxiliary heat exchanger channel 202 and the bypass channel 203, and the in-vehicle auxiliary heat exchanger 102 of the above-mentioned air-conditioning module is arranged in the auxiliary heat exchanger channel 202.

[0019] The external heat exchanger 105 , the internal main heat exchanger 103 and the internal auxiliary heat exchanger 102 are fin-tube heat exchangers or parallel flow heat exchangers, and the external fan 106 is installed on the surface of the external heat exchanger 105 .

[0020] The regenerator 107 is a counter-flow heat exchanger.

[0021] The first four-way reversing valve 112 and the second four-way reversing valve 104 realize switching between the first working mode and the second working mode by different internal conduction modes of the four connection ports; wherein, the first working mode is that port a and port b are internally connected, and port c and port d are internally connected; the second working mode is that port a and port d are internally connected, and port b and port c are internally connected.

[0022] The three-way valve 109 realizes switching between the first working mode and the second working mode by different internal conduction modes of the three connection ports; wherein, the first working mode is that port a and port b are internally connected, and port b and port c are not connected; the second working mode is that port b and port c are internally connected, and port a and port b are not connected.

[0023] The air conditioning damper 204 of the air conditioning box 201 realizes the switching between the first working mode and the second working mode by controlling the different air flow paths, wherein, in the first working mode, the air conditioning damper 204 opens the auxiliary heat exchanger side channel 202 and closes the bypass channel 203, and all the air from the main heat exchanger 103 in the vehicle flows through the auxiliary heat exchanger 102 in the vehicle; the second working mode is that the air conditioning damper 204 opens the bypass channel 203 and closes the auxiliary heat exchanger side channel 202, and all the air from the main heat exchanger 103 in the vehicle flows through the bypass channel 203.

[0024] The present invention also proposes a control method for the above-mentioned ejector-enhanced CO2 heat pump air-conditioning system for new energy vehicles. The system working modes include a cooling mode with heat recovery, a cooling mode without heat recovery, a heating mode with heat recovery, a heating mode without heat recovery, a defrosting mode and a defrosting mode. The system working mode is switched by controlling the first four-way reversing valve 112, the second four-way reversing valve 104, the three-way valve 109, the electronic expansion valve 111, the vehicle outer side fan 106, the air-conditioning damper 204 and the air-conditioning fan 205. The specific implementation steps are: (1) Cooling mode with heat recovery: When the passenger compartment requests cooling and the system determines that heat recovery is beneficial, the system starts the cooling mode with heat recovery, the compressor 101 is turned on, the first four-way reversing valve 112 is switched to the first working mode, the second four-way reversing valve 104 is switched to the first working mode, the three-way valve 109 is switched to the first working mode, the air conditioning damper 204 is switched to the second working mode, the air conditioning fan 205 is turned on, the vehicle outer side fan 106 is turned on, and the electronic expansion valve 111 is turned on and automatically adjusts the opening according to the system working conditions; (2) Non-regenerative cooling mode: When the passenger compartment requests cooling and the system determines that the regenerative cooling is harmful, the system starts the non-regenerative cooling mode, the compressor 101 is turned on, the first four-way reversing valve 112 is switched to the first working mode, the second four-way reversing valve 104 is switched to the first working mode, the three-way valve 109 is switched to the second working mode, the air conditioning damper 204 is switched to the second working mode, the air conditioning fan 205 is turned on, the vehicle outer side fan 106 is turned on, and the electronic expansion valve 111 is turned on and automatically adjusts the opening according to the system operating conditions; (3) Heating mode with regenerative heating: When the passenger compartment requests heating and the system determines that regenerative heating is beneficial, the system starts the heating mode with regenerative heating, the compressor 101 is turned on, the first four-way reversing valve 112 is switched to the second working mode, the second four-way reversing valve 104 is switched to the second working mode, the three-way valve 109 is switched to the first working mode, the air conditioning damper 204 is switched to the first working mode, the air conditioning fan 205 is turned on, the vehicle outer side fan 106 is turned on, and the electronic expansion valve 111 is turned on and automatically adjusts the opening according to the system operating conditions; (4) Heating mode without reheating: When the passenger compartment requests heating and the system determines that the reheating is harmful, the system starts the heating mode without reheating, the compressor 101 is turned on, the first four-way reversing valve 112 is switched to the second working mode, the second four-way reversing valve 104 is switched to the second working mode, the three-way valve 109 is switched to the second working mode, the air conditioning damper 204 is switched to the first working mode, the air conditioning fan 205 is turned on, the vehicle outer side fan 106 is turned on, and the electronic expansion valve 111 is turned on and automatically adjusts the opening according to the system operating conditions; (5) Demisting mode: When the passenger compartment requests demisting, the system starts the demisting mode, the compressor 101 is turned on, the first four-way reversing valve 112 is switched to the first working mode, the second four-way reversing valve 104 is switched to the first working mode, the three-way valve 109 is switched to the first working mode, the air conditioning damper 204 is switched to the first working mode, the air conditioning fan 205 is turned on, and the vehicle outer side fan 106 is turned off; (6) Defrost mode: When the external heat exchanger needs to be defrosted, the system starts the defrost mode, the compressor 101 is turned on, the first four-way reversing valve 112 is switched to the first working mode, the second four-way reversing valve 104 is switched to the first working mode, the three-way valve 109 is switched to the first working mode, the air conditioning damper 204 is switched to the second working mode, the air conditioning fan 205 is turned off, the external fan 106 is turned off, and the electronic expansion valve 111 is turned on and maintained at the maximum opening.

Claims

1. An ejector-enhanced CO2 heat pump air conditioning system for new energy vehicles, characterized in that: Contains air conditioning module and air conditioning box module; The air conditioning module includes a compressor, the compressor outlet is connected to the inlet of the auxiliary heat exchanger in the vehicle, the outlet of the auxiliary heat exchanger in the vehicle is connected to the a port of the first four-way reversing valve, the b port of the first four-way reversing valve is connected to the inlet of the heat exchanger outside the vehicle, the outlet of the heat exchanger outside the vehicle is connected to the a port of the second four-way reversing valve, the b port of the second four-way reversing valve is connected to the hot fluid side inlet of the regenerator, the hot fluid side outlet of the regenerator is connected to the primary fluid inlet of the ejector, the secondary fluid inlet of the ejector is connected to the d port of the second four-way reversing valve, the c port of the second four-way reversing valve is connected to the outlet of the main heat exchanger in the vehicle, the inlet of the main heat exchanger in the vehicle is connected to the d port of the first four-way reversing valve, the c port of the first four-way reversing valve is connected to the outlet of the electronic expansion valve, the inlet of the electronic expansion valve is connected to the liquid outlet of the gas-liquid separator, the inlet of the gas-liquid separator is connected to the outlet of the ejector, the gas outlet of the gas-liquid separator is connected to the b port of the three-way valve, the a port of the three-way valve is connected to the cold fluid side inlet of the regenerator, and the cold fluid side outlet of the regenerator is connected to the compressor inlet and the c port of the three-way valve; The air-conditioning box module includes an air-conditioning box body, an air-conditioning fan and an air-conditioning damper; wherein, the front part of the air-conditioning box body is a single-channel structure, and the rear part is divided into an independent auxiliary heat exchanger channel and a bypass channel, the auxiliary heat exchanger channel and the bypass channel are parallel structures, and the inlet and outlet are connected together; the air-conditioning fan is arranged at the inlet of the air-conditioning box body, the in-vehicle main heat exchanger of the above-mentioned air-conditioning module is arranged at the rear side of the air-conditioning fan, the air-conditioning damper is installed at the inlet of the auxiliary heat exchanger channel and the bypass channel, and the in-vehicle auxiliary heat exchanger of the above-mentioned air-conditioning module is arranged in the auxiliary heat exchanger channel.

2. The ejector-enhanced CO2 heat pump air conditioning system for new energy vehicles according to claim 1, characterized in that: The external heat exchanger, the internal main heat exchanger and the internal auxiliary heat exchanger are fin-tube heat exchangers or parallel flow heat exchangers, and the external fan is installed on the surface of the external heat exchanger.

3. The ejector-enhanced CO2 heat pump air conditioning system for new energy vehicles according to claim 1, characterized in that: The regenerator is a counter-flow heat exchanger.

4. The ejector-enhanced CO2 heat pump air conditioning system for new energy vehicles according to claim 1, characterized in that: The first four-way reversing valve and the second four-way reversing valve realize the switching between the first working mode and the second working mode through the different internal conduction modes of the four connection ports; wherein the first working mode is that the a port and the b port are internally connected, and the c port and the d port are internally connected; the second working mode is that the a port and the d port are internally connected, and the b port and the c port are internally connected; The three-way valve realizes the switching between the first working mode and the second working mode by different internal conduction modes of the three connection ports; wherein the first working mode is that the a port and the b port are internally connected, and the b port and the c port are not connected; the second working mode is that the b port and the c port are internally connected, and the a port and the b port are not connected; The air-conditioning damper of the air-conditioning box realizes the switching between the first working mode and the second working mode by controlling the different air flow paths, wherein the first working mode is that the air-conditioning damper opens the auxiliary heat exchanger side channel and closes the bypass channel, and the air from the main heat exchanger in the vehicle all flows through the auxiliary heat exchanger in the vehicle; the second working mode is that the air-conditioning damper opens the bypass channel and closes the auxiliary heat exchanger side channel, and the air from the main heat exchanger in the vehicle all flows through the bypass channel.

5. A control method for an ejector-enhanced CO2 heat pump air conditioning system for a new energy vehicle based on any one of claims 1 to 4, characterized in that: The system working modes include cooling mode with heat recovery, cooling mode without heat recovery, heating mode with heat recovery, heating mode without heat recovery, defog mode and defrost mode. The system working modes are switched by controlling the first four-way reversing valve, the second four-way reversing valve, the three-way valve, the electronic expansion valve, the vehicle outer side fan, the air conditioning damper and the air conditioning fan. The specific implementation steps are as follows: (1) Cooling mode with heat recovery: When the passenger compartment requests cooling and the system determines that heat recovery is beneficial, the system starts the cooling mode with heat recovery, the compressor starts, the first four-way reversing valve switches to the first working mode, the second four-way reversing valve switches to the first working mode, the three-way valve switches to the first working mode, the air conditioning damper switches to the second working mode, the air conditioning fan starts, the vehicle outer fan starts, and the electronic expansion valve opens and automatically adjusts the opening according to the system operating conditions; (2) Non-regenerative cooling mode: When the passenger compartment requests cooling and the system determines that the regenerative cooling is harmful, the system starts the non-regenerative cooling mode, the compressor starts, the first four-way reversing valve switches to the first working mode, the second four-way reversing valve switches to the first working mode, the three-way valve switches to the second working mode, the air conditioning damper switches to the second working mode, the air conditioning fan starts, the vehicle outer side fan starts, and the electronic expansion valve opens and automatically adjusts the opening according to the system operating conditions; (3) Heating mode with regenerative heating: When the passenger compartment requests heating and the system determines that regenerative heating is beneficial, the system starts the heating mode with regenerative heating, the compressor starts, the first four-way reversing valve switches to the second working mode, the second four-way reversing valve switches to the second working mode, the three-way valve switches to the first working mode, the air conditioning damper switches to the first working mode, the air conditioning fan starts, the vehicle outer side fan starts, and the electronic expansion valve opens and automatically adjusts the opening according to the system operating conditions; (4) Non-regenerative heating mode: When the passenger compartment requests heating and the system determines that regenerative heating is harmful, the system starts the non-regenerative heating mode, the compressor starts, the first four-way reversing valve switches to the second working mode, the second four-way reversing valve switches to the second working mode, the three-way valve switches to the second working mode, the air conditioning damper switches to the first working mode, the air conditioning fan starts, the vehicle outer side fan starts, and the electronic expansion valve starts and automatically adjusts the opening according to the system operating conditions; (5) Demisting mode: When the passenger compartment requests demisting, the system starts the demisting mode, the compressor starts, the first four-way reversing valve switches to the first working mode, the second four-way reversing valve switches to the first working mode, the three-way valve switches to the first working mode, the air conditioning damper switches to the first working mode, the air conditioning fan starts, the vehicle outer fan is turned off, and the electronic expansion valve opens and automatically adjusts the opening according to the system operating conditions; (6) Defrost mode: When the external heat exchanger needs to be defrosted, the system starts the defrost mode, the compressor starts, the first four-way reversing valve switches to the first working mode, the second four-way reversing valve switches to the first working mode, the three-way valve switches to the first working mode, the air conditioning damper switches to the second working mode, the air conditioning fan turns off, the external fan turns off, and the electronic expansion valve opens and maintains the maximum opening.

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