1. What is a CO2 heat pump water heater?
The CO2 heat pump is a heat pump system that uses CO2 as the refrigerant. Because the CO2 refrigerant code is R-744, the CO2 heat pump is also called R744 heat pump.
2. Working principle of CO2 heat pump
The working principle of the CO2 heat pump is basically the same as that of the ordinary heat pump. During the set time, when the water temperature of the hot water storage tank is lower than the set value of the temperature controller, the heat pump, fan and circulating water pump are automatically turned on, and the fan draws air into the evaporator. After the heat medium in the evaporator absorbs the heat energy in the air, it is pressurized by the heat pump (compressor) to generate high temperature, and then the heat is released to the water through the heat exchanger to increase the water temperature, and the heat medium flows through the throttle valve after cooling down. Return to the evaporator, repeating heat absorption and heat release, until the temperature of the heated water reaches the set temperature, the heat pump and fan stop working.

3. Advantages of CO2 heat pump water heater:

1) The cooling capacity per unit volume of CO2 is several times that of other refrigerants. Its excellent flow and heat transfer characteristics can significantly reduce the size of the compressor and the system, making the entire system very compact;

2) The CO2 refrigerant has almost no destructive effect on the ozone layer, and the GWP is also low;

3) High thermal efficiency CO2 refrigerant combined with off-peak electricity charges at night will greatly reduce operating costs;

4) Good performance and chemical stability, CO2 is safe, non-toxic, non-flammable, suitable for various lubricating oils and common mechanical parts and materials, and will not decompose to produce harmful gases even at high temperatures;

5) It has thermodynamic properties compatible with the refrigeration cycle and equipment, and the latent heat of evaporation of CO2 is relatively large;

6) Compared with conventional refrigerants, the compression of CO2 transcritical cycle is relatively small, about 2.5-3.0, which can improve the operating efficiency of the compressor, thereby increasing the coefficient of performance of the system.

7) The use of CO2 exhaust temperature is higher, can get higher temperature hot water, adjustable in the range of 55~90℃; CO2 heat pump can work at -20℃, even in severe cold environment can also supply 90℃ hot water.

8) CO2 is an inexhaustible and inexhaustible natural substance on the earth. As a natural refrigerant working medium, CO2 is regarded as CFC due to its environmental protection, non-toxicity and excellent transcritical cycle characteristics. The best substitute for refrigerants.

4. The difference with ordinary heat pump:

CO2 heat pump water heater use CO2 as the refrigerant. Ordinary heat pumps generally use environmentally friendly refrigerants as the refrigerant. The working principles of the two are basically the same. Both belong to the vapor compression type, but they are slightly different. The CO2 heat pump belongs to the supercritical cycle, that is, condensing. At the condenser end, CO2 will not be condensed into liquid, while Freon refrigerant is condensed into liquid at the condenser end and then throttled.

5. Development limitations of CO2 heat pumps:

The main disadvantage of CO2 as a refrigerant is that it has a lower critical temperature (31.1°C) and a higher critical pressure (7.37MPa). Especially for the latter, if the transcritical cycle is adopted, the working pressure of the CO2 refrigeration system can reach up to 10 MPa, which has more stringent requirements on the material strength, sealing and pipe connection of the system. Undoubtedly, the production cost is also other air sources. Several times the heat pump unit.