The influences of the oil circulation ratio on the performance of a vapor injection scroll compressor in heat pump air conditioning system intended for electrical vehicles

•The performance of a scroll compressor under two operating conditions was assessed.•The optimal OCR values for the two conditions were found to be 3.5% and 5.5% respectively.•Optimal air injection pressures on the two conditions were 0.27 and 0.45 Mpa respectively.•An empirical formula for the heating capacity as a function of vapor injection coefficient and OCR was derived.