The air-conditioning system of new energy vehicles mainly consists of a ventilation system, a cooling system, a heating system, an air purification system, and a control system.
I. Working Principle of the Air Conditioning Cooling System
The function of the cooling system is to cool the air inside the vehicle or the fresh air entering from the outside, thus reducing the temperature inside the vehicle.
1 - Fan 2 - Condenser 3 - Compressor 4 - Expansion valve 5 - Blower 6 - Evaporator 7 - Receiver-drier
1. Cooling Route Inside the Vehicle
The refrigerant is charged in a closed cooling system. Under the action of the compressor, the refrigerant circulates. It condenses from gaseous to liquid at the condenser, releasing heat; and it evaporates from liquid to gaseous at the evaporator, absorbing heat, thus reducing the temperature inside the vehicle.
1 - Condenser 2 - Electric compressor 3 - Receiver-drier 4 - Power storage battery unit 5 - Electric fan 6 - Expansion valve 7 - Heat exchanger 8 - Blower 9 - Evaporator inside the vehicle 10 - Expansion valve for cooling inside the vehicle
2. Cooling Route of the Battery Pack
The refrigerant circulation loop of the air conditioning system consists of two parallel branches: one for cooling inside the vehicle and one for cooling the power storage battery unit. Each branch has an expansion valve for independently controlling the cooling function.
The energy storage management electronic device can control and open the expansion valve by applying a voltage, so that the refrigerant can flow into the power storage battery unit, thus cooling the power storage battery. The cooling inside the vehicle is also carried out as needed, and the expansion valve in front of the evaporator is controlled by the electrical and electronic system.
1 - Condenser 2 - Electric compressor 3 - Receiver-drier 4 - Power storage battery unit 5 - Electric fan 6 - Expansion valve 7 - Heat exchanger 8 - Blower 9 - Evaporator inside the vehicle 10 - Expansion valve for cooling inside the vehicle
II. Working Principle of Air Conditioning Heating
In the early days, electric vehicle heaters usually used electric heaters. Nowadays, more and more electric vehicle heaters adopt heat pumps and air conditioning for heating. When the refrigerant of the air conditioning system flows in a specific direction, it is in the cooling mode. At this time, the condenser and the evaporator perform their respective functions, and the evaporator is responsible for cooling the inside of the vehicle. When the refrigerant flows in the reverse direction, it enters the heating mode. At this time, the evaporator becomes a condenser and is responsible for heating the inside of the vehicle. The heating efficiency of air conditioning is 3 to 4 times that of an electric heater and is more energy-efficient. Therefore, more and more electric vehicle heaters are changed to air conditioning heating.
1. Working Principle of PTC Water Heating Heater
Pure electric vehicles can use PTC heaters to directly heat the air or use PTC heaters to heat the coolant to heat the air. When using PTC heaters to directly heat the air, only replacing the heater core of a traditional vehicle air conditioner with a PTC heater and supplementing with necessary control equipment can be directly applied to a pure electric vehicle.
2. Heat Pump Air Conditioning
Compared with PTC heaters, heat pump air conditioning can significantly reduce energy consumption and increase the winter driving range of vehicles. However, the low-temperature heating efficiency of heat pump systems is low and the cost is relatively high. Therefore, most vehicle manufacturers still use PTC heaters for heating. In the future, with the continuous breakthrough of low-temperature heat pump technology, the application of heat pump air conditioning will become more widespread.
Composition of heat pump air conditioning system: 1 - Expansion valve on the power storage battery unit 2 - Electric compressor 3 - Blower for the vehicle interior space 4 - Electric heating device 5 - Expansion valve for the evaporator of the vehicle interior space 6 - Shut-off valve between the condenser and the dryer bottle 7 - Shut-off valve between the electric compressor and the heat pump heat exchanger 8 - Heat pump heat exchanger 9 - Receiver-drier
There are three working modes for electric vehicle air conditioning heating: air mode, coolant mode, and air + coolant mode.
(1) Air Mode
The air conditioning compressor presses the high-temperature and high-pressure refrigerant gas into the condenser. The refrigerant flowing out of the condenser then flows into the thermal expansion valve. After flowing out of the thermal expansion阀, the temperature is reduced a bit, and then it flows into two condensers to achieve two heating processes and improve the heating effect. Then the refrigerant flows into another thermal expansion阀 and then into the evaporator. Because the temperature of the refrigerant in the evaporator is lower than the surrounding air temperature, it will absorb the surrounding air heat and vaporize. The low-temperature and low-pressure refrigerant gas finally flows back to the compressor for the next cycle.
(2) Coolant Mode
If the outside air temperature is extremely low, lower than the temperature of the refrigerant in the evaporator, the refrigerant will flow into the heat exchanger. In the heat exchanger, two water pipes connected to the refrigerant and two water pipes connected to the coolant interact, and the refrigerant can absorb the heat of the coolant of the electric vehicle cooling system. If the coolant heat of the cooling system is insufficient, the electric heater will work to heat the coolant.
(3) Air + coolant Mode
The refrigerant flows both to the evaporator and to the evidencector, absorbing heat from both the air and the coolant. When the vehicle is running, the control unit will select different working modes according to the environment temperature. There is also an intelligent mode. In the cooling mode, the refrigerant flow direction changes, and the functions of the evaporator and the condenser are interchanged. One of the condensers will be separated by a partition and will not work. There are two three-way valves in the electric vehicle cooling system, which can achieve the switching of the large and small cycles of the cooling system.
III. Working Principle of the Heating System
1. Working Principle of the Water Heating System
1- Heater core 2- Heater hose 3- Hot water valve 4- Radiator hose 5- Expansion tank 6- Water pump 7- Fan 8- Radiator 9- Engine
2. Working Principle of the Heat Pump Air Conditioning Heating System
1- Evaporator 2- Electric fan 3- Electric compressor 4- Liquid storage dryer 5- Power battery unit 6- Expansion valve for heat pipe in power battery unit 7- Heat pipe in power battery unit 8- In-vehicle space blower 9- Expansion valve for evaporator in vehicle interior 10- Condenser 11- Warm air heat exchanger 12- Electric heating device 13- Heat pump heat exchanger 14- Expansion valve for heat pump heat exchanger 15- Electric coolant pump 16- Coolant replenishing tank 17- Stop valve between electric compressor and evaporator (open when the valve is not powered) 18- Stop valve between evaporator and liquid storage dryer (closed when the valve is not powered) 19- Refrigerant one-way valve 20- Stop valve between electric compressor and heat pump heat exchanger (open when the valve is not powered) 21- Stop valve between expansion valve on heat pump heat exchanger and liquid storage dryer (open when the valve is not powered)
