Principle of heat recovery in heat pumps
The core of heat recovery in heat pumps is to utilize the condensation heat that was originally wasted in the refrigeration cycle and recover it for heating water or air.
Basic heat pump cycle (cooling mode)
In normal cooling mode, the condenser of the heat pump will discharge heat to the environment (air or water), which is usually wasted. In heat recovery mode, this part of the heat is recovered and utilized.
Key components
Compressor
Compresses the refrigerant to increase its temperature and pressure.
01
Condenser (heat recovery end)
The refrigerant releases heat here, and the recovered heat is used to heat water or air.
02
Expansion valve
Reduces the refrigerant pressure, causing it to evaporate and absorb heat.
03
Evaporator
The refrigerant absorbs heat from the environment (cooling).
04
Heat recovery heat exchanger (optional)
An additional heat exchange device for more efficient heat recovery.
05
Workflow of heat recovery in heat pumps
Single heat recovery mode (partial heat recovery)
- Applicable to situations where cooling and a small amount of hot water are required at the same time (such as air conditioning + domestic hot water).
- The refrigerant absorbs indoor heat in the evaporator (cooling).
- High-temperature and high-pressure refrigerant enters the condenser, and part of the heat is used to heat the water, while the remaining heat is still dissipated through the cooling tower or air cooling.
- The refrigerant returns to the evaporator after being throttled by the expansion valve, and the cycle continues.
Full heat recovery mode (100% heat recovery)
- Applicable to heating first, or when the cooling demand is low (such as heat recovery in winter).
- The refrigerant absorbs heat from the air/water in the evaporator (similar to air source heat pump).
- All condensation heat is recovered and used for heating or hot water, and no heat is discharged to the environment.
- The system can be switched to pure heating mode (such as heating in winter).
Typical Applications
| Application | Heat Recovery Use Case | Key Benefit |
| Hotels/Hospitals | Domestic hot water + air conditioning cooling | Reduces boiler energy consumption |
| Data Centers | Recovers server waste heat for space heating | Lowers PUE (Power Usage Effectiveness) |
| Swimming Pools | Uses AC waste heat to warm pool water | Saves >50% energy |
| Industrial Cooling | Recovers refrigeration system waste heat for process heating | Reduces steam demand |