Conventional defrosting characteristics for variable frequency multi-split air-source heat pumps

To study the defrosting performances, sets up a multi-split air-source heat pump system test rig using R410A as refrigerant. Conducts the experimental research under simulated indoor and outdoor environments, measures the defrosting performances such as pressure and temperature, and analyses the defrosting time, pressure and frequency change during defrosting. The results indicate that during defrosting average suction pressure is 0.30 MPa, the lowest indoor unit coil temperature is -26.4 ℃, and the highest compressor speed is 90 r/s. Points out the constraints of fast defrost and the improved method for defrosting, which provides some guidance for the defrosting of multi-split air-source heat pump.