Experimental study on effect of superheat degree in an organic Rankine cycle with a scroll expander

Abstract

A micro-organic Rankine cycle (ORC) system utilizing R134a as the working fluid and a scroll expander has been developed. In this study, the effects of superheat degree on system performance were investigated by varying the evaporation temperature and refrigerant mass flow rate. The heat sources used in the ORC system were three different temperatures: 85℃, 95℃, and 105℃. The results indicate that the refrigerant mass flow rate increases with the rise in evaporation pressure, while superheat degree decreases. Moreover, higher superheat degrees led to a reduction in the system power generation. The trend of net efficiency demonstrates that when superheat degree increases, the net efficiency first rises to a peak before declining. At heat source temperatures of 85℃, 95℃, and 105℃, the peak net efficiencies are 4.86%, 5.56%, and 5.87%, respectively, with corresponding superheat degrees of 25.72K, 36.16K, and 38.15K.