Currently, the nanofluids are used as a nano refrigerant to perform better heat transfer in refrigeration systems. In this current study, the efficiency of VCRS utilising R600a (varying mass charges 20, 30, 40, 50 and 60 g) along with ZnO nanoparticles concentration (0.3, 0.5 and 0.7 g/L). In this experiment, the performance parameters such as evaporator temperature (ET), cooling capacity (CC), power consumption (PC) and coefficient of performance (COP) were investigated. From the experimental results, it was found that 30 g mass of R660a refrigerant at 0.5 g/L ZnO nanoparticle concentration provides higher effect of refrigeration and it reduces compressor work of 150W compared with pure R600a and has 0.3 g/L and 0.7 g/L nanoparticle concentrations at different mass fraction. Addition of ZnO nanoparticles exhibits increase in COP of 2.8 at 0.5 g/L nano refrigerant against pure R 600a refrigerant and having 0.5 g/L nano refrigerant at lower evaporator temperature of − 14 °C along with power consumption of 0.083 kW. Increase in COP of nano refrigerant causes decrease in power consumption.