Experimental study on influence of hydrocarbon blends on performance of auto-cascade refrigerating cycle systems

In order to study the influence of hydrocarbon (HC) blends on the performance of auto-cascade refrigerating cycle (ARC) systems,this paper selects R600a,R1150 and R50 for a typical three-stage ARC system to study the influence of different ratios of HC blends on suction and discharge temperatures,suction and discharge pressures,evaporation temperatures,system refrigeration capacity and COP,and compares the performance with that of an ARC system using the blends of R600a/R23/R14.The results show that with the increase of the mass fraction of R1150 in the blends from 15% to 31%,the evaporation temperature,suction and discharge pressures and discharge temperature of the system all increase by more than 4.64%,which leads to the decrease of system refrigeration capacity and COP by about 5% to 8% and 17.5% to 30.0%,respectively.With the increase of R50 mass fraction from 2% to 12%,the suction and discharge pressures and temperatures of the system are still on the rise,but the evaporation temperature decreases,with the largest decrease of 22.79%,which improves the refrigeration capacity by about 14.49% to 20.82%,and decreases the COP of the system by more than 8.91%.The discharge temperature of the ARC system using HC blends is higher than that of the R600a/R23/R14 system by 15 ℃,but the pressure ratio and power fluctuation of its compressor are reduced by 27% and 57%,respectively.