Working principle of heat pump water heater

Detailed explanation of the working principle of heat pump water heater

一、Core work cycle

The heat pump water heater achieves heat transfer through reverse Carnot cycle, which mainly includes four key processes:

‌1、Evaporative heat absorption

Low temperature liquid refrigerants (such as R32) absorb heat from air/water sources in the evaporator and evaporate into low-temperature gas. This process can lower the evaporator temperature to 6.5 ℃, creating a significant temperature difference with the environment.

‌2、Compression heating

The compressor compresses low-temperature gaseous refrigerant into high-temperature and high-pressure gas (with a temperature of up to 80-120 ℃), which consumes electricity but has an energy efficiency ratio (COP) of 3-5.

‌3、Condensation releases heat

High temperature refrigerant exchanges heat with water in the condenser, releasing heat to heat the water tank (increasing temperature by 40-60 ℃). The refrigerant condenses itself into a high-pressure liquid.

‌4、Throttling and pressure reduction

The liquid refrigerant returns to the evaporator after being depressurized by the electronic expansion valve, completing the cycle.

二、Key component functions

1. Compressor, function: provide driving pressure and increase refrigerant temperature

2. Condenser, function: exchange heat with water, release heat to heat the water tank

3. Electronic expansion valve, function: precise control of refrigerant flow and pressure

三、Energy efficiency characteristics

COP value: Under standard operating conditions, it can reach 4.0-5.0 (i.e. 1 degree of electricity can transport 4-5 degrees of heat)

Low temperature impact: Electric assisted heating may be activated below -7 ℃, resulting in a decrease of about 30% in efficiency

Defrosting mechanism: Regular defrosting is required in high humidity environments, which affects 5-10% of the operating time