PAG oil with low mutual solubility is selected as the lubricating oil of some R290 air conditioner compressors.In the case of viscosity conditions,the use of low misci-ble lubricating oil is conducive to reducing the amount of system filling.Because the R290 air conditioner has the characteristics of low charge and large displacement compressor,under low temperature conditions,the refrigerant/lubricating oil mixture with poor mutual solubility is easy to flow in layers,and abnormal throttling may occur in the de-frosting restart process of air conditioning heating mode.This paper analyzes and optimizes the abnormal throttling phenomenon of R290 air conditioner under low tempe-rature conditions from the aspects of compressor oil return,throttling characteristics and expansion valve opening control.
hermetic rotary compressor of R290throttle characteristicsoil block