Heat Pump Air Conditioning System
The core component enabling the functionality of the heat pump air conditioning system is the four-way reversing valve. It adjusts the flow direction of the refrigerant within the system, allowing for switching between cabin cooling and cabin heating modes. The system's greatest advantage is its high energy efficiency.
Heat Pump Air Conditioning Cooling Principle
Key components: Electric compressor, four-way reversing valve, external condenser, expansion valve, internal evaporator.
Cooling cycle process:
1) Compression process
The compressor draws in low-temperature, low-pressure gaseous refrigerant from the evaporator, compresses it, and discharges high-temperature, high-pressure gaseous refrigerant toward the four-way reversing valve.
In cooling mode, the four-way valve switches the flow path to direct the high-temperature, high-pressure gas to the external condenser.
2) Condensation and heat rejection (external condenser)
The high-temperature, high-pressure gaseous refrigerant enters the external condenser and releases heat to the outside environment. The refrigerant condenses from a gas into a medium-temperature, high-pressure liquid, rejecting heat (labeled "Heat Rejection" in the diagram).
3) Throttling and pressure reduction (expansion valve)
The high-pressure liquid refrigerant flows through the expansion valve. As it passes through the small orifice (throttling), its pressure and temperature drop sharply, transforming it into a low-temperature, low-pressure mist-like mixture of gas and liquid, which flows to the internal evaporator.
4) Evaporation and heat absorption (internal evaporator)
The low-temperature, low-pressure two-phase refrigerant enters the internal evaporator and absorbs heat from the cabin air, causing the refrigerant to boil and vaporize; the cabin air is cooled, thereby lowering the cabin temperature. After absorbing heat, the refrigerant becomes a low-temperature, low-pressure gas.
5) Return flow and cycle completion
The low-temperature, low-pressure gaseous refrigerant flows back to the four-way reversing valve; the valve directs the flow back to the compressor's suction inlet, initiating the next cycle. Heat Pump Air Conditioning Heating Principle
Key components: Electric compressor, four-way reversing valve, in-cabin condenser, expansion valve, external evaporator.
Heating cycle process
1) Compression process
The compressor draws in low-temperature, low-pressure gaseous refrigerant from the external evaporator, compresses it by performing work, and outputs high-temperature, high-pressure gaseous refrigerant into the four-way reversing valve. The valve spool shifts to redirect the flow, sending the high-temperature, high-pressure gaseous refrigerant to the in-cabin condenser.
2) Condensation and heat release (in-cabin; core heating stage)
The high-temperature, high-pressure gaseous refrigerant enters the in-cabin condenser and exchanges heat with the cool air inside the cabin, releasing a large amount of heat (labeled "Heat Release" in the diagram) to warm the air and raise the cabin temperature. After releasing heat, the refrigerant undergoes a phase change, condensing from a gas into a medium-temperature, high-pressure liquid before flowing out of the condenser.
3) Throttling and pressure reduction (expansion valve)
The medium-temperature, high-pressure liquid refrigerant flows through the expansion valve; due to the throttling orifice, its pressure and temperature drop sharply, transforming it into a low-temperature, low-pressure mist-like gas-liquid mixture that flows toward the external evaporator.
4) Evaporation and heat absorption (external heat exchanger)
The low-temperature, low-pressure two-phase refrigerant enters the external evaporator and absorbs heat from the ambient air, causing the refrigerant to boil and vaporize into a low-temperature, low-pressure gas; it extracts low-grade thermal energy from the environment even when ambient temperatures are low.
5) Return flow and cycle completion
The low-temperature, low-pressure gaseous refrigerant re-enters the four-way reversing valve and flows back to the compressor's suction port, initiating the next cycle.
