To model the electrical efficiency of a compressor that can apply a suction refrigerant state under both superheated and two-phase conditions

the performance of an R32 variable frequency rotary compressor

which varies with the compressor frequency

pressure ratio

and evaporating temperature

is analyzed in this paper. The results show that when the system is at a fixed pressure ratio and evaporating temperature

the electrical efficiency linearly decreases with the declining superheated temperature and an increase in suction vapor quality. Moreover

the slope under two-phase suction is above that under superheated suction. In addition

the electrical efficiency of the system at a fixed pressure ratio is inversely proportional to the evaporating temperature

and that of the system at a fixed evaporating temperature is also inversely proportional to the pressure ratio. The more the pressure ratio varies

the smaller the influence of the evaporating temperature. To demonstrate the precision of the model

the theoretical value is compared with the experiment results in this paper. The maximum of relative error is 1.83%

and the minimum is 0.03%. The performance of a compressor at low frequency will deteriorate

which leads to the inaccuracy of the model

and therefore the model is suitable for operating conditions with a frequency higher than the rated frequency and a suction vapor quality higher than 0.88.