Frosting Effect of Air Source Heat Pump Unit and Its Solution

Air source heat pump as a low-temperature heat source of air, through a small amount of skills to drive the low temperature heat in the air to enhance the use of high heat to the device, with high efficiency and environmental protection and pollution-free features. With the air source heat pump technology is mature, in China's northern coal to electricity to large-scale development, air source heat pump heating alternative to coal heating the main force in the coal to play a huge role in electricity.

In the northern winter climate conditions are generally poor, with the outdoor temperature is declining, frosting problem becomes a lot of air source heat pump manufacturers one of the technical problems, the main reason is that the frost will heat pump unit operation has two main effects, one a large number of frost build-up will reduce the heat transfer performance of the evaporator; its second frost hinders the outdoor gas flow, the fan energy loss increases.

With the increase of the outdoor wall heat exchanger wall frost layer, the outdoor heat exchanger evaporator temperature decreases, the unit heat is reduced, the fan type attenuation, the input current increases, the heating coefficient coefficient is reduced, the compressor will even stop when serious run, so defrosting becomes the technical problem that air source heat pump unit must solve in normal operation.

Defrosting Although there are many ways to achieve, but some of the technical strength of the heat pump manufacturers is not enough, in order to ensure the heat pump unit heating, can only use the auxiliary heat, not only reduces the air source heat pump unit COP, operating costs are greatly increased. In general defrosting are stop defrosting, electric heating defrost, heat bypass defrost, reverse cycle defrost, etc., which is the most commonly used defrosting defrosting method.

Reverse cycle defrosting is through the use of four-way valve, so that the refrigerant flow changes, the heating process is converted to refrigeration process. During the defrosting, the refrigerant is discharged from the overheated state and the refrigerant vapor is fed into the outdoor coil for defrosting. When the defrost is completed, the heat pump runs again and restarts. This method does not require any equipment, only need to adjust the four-way valve when defrosting can be.