Why The Evaporator Is A Critical Part Of The Heat Pump Cycle?

Why The Evaporator Is A Critical Part Of The Heat Pump Cycle?

Whether it is an air source heat pump or a ground source (geothermal) heat pump, the evaporator is the key component of the heat pump system. The main function of the evaporator is to absorb heat from the surrounding environment to evaporate the refrigerant, and then bring the heat to the compressor where it is further concentrated and released.

The following is the working principle of evaporator in heat pump system:

1. Heat absorption: the evaporator is the part of the heat pump system that is in contact with the heat source. For air-source heat pumps this is usually the outdoor air, while for ground-source heat pumps it is the relatively stable temperature of the ground or water source. When the heat pump is in heat production mode, the evaporator absorbs heat from the surrounding environment.

2. Refrigerant circulation: A low-pressure, low-temperature refrigerant (usually hydrofluorocarbon (HFC) or HFC refrigerant) circulates inside the evaporator coil or tubing. As the refrigerant passes through the coil, it is exposed to a heat source (air, ground or water) through the surface of the coil. The heat from the heat source causes the refrigerant to evaporate, changing it from a liquid to a gaseous state.

3. Low pressure vapour: The refrigerant vapour leaving the evaporator is at a lower temperature and pressure than in its initial state. It absorbs heat energy from a heat source and is then carried by the refrigerant and turned into a vapour.

4. Compressor: The low-pressure, low-temperature refrigerant vapour is drawn into the compressor, which is usually located inside the heat pump unit. The function of the compressor is to increase the pressure and temperature of the vapour and concentrate the heat energy absorbed during evaporation.

5. Heat Release: The high pressure, high temperature vapour is then transferred to the condenser coil or piping, where the absorbed heat is released into the indoor space in the case of the heating cycle. In the case of the cooling cycle, the heat is released to the outdoor environment.

6. Repeat process: The refrigerant is then condensed back to liquid form in the condenser and the cycle is repeated.

Overall, the evaporator is a key part of the heat pump cycle as it helps to transfer thermal energy from the heat source to the refrigerant, which is then used to heat or cool the space as required. The efficiency and effectiveness of a heat pump system depends on the proper operation of the evaporator and the refrigerant used. It is important to maintain the evaporator and the entire heat pump system to ensure optimal performance.