For the purpose of effective utilization of hot dry rock resource, a double-stage Organic Rankine Cycle (ORC) power generation system is established in present work. Six kinds of organic working fluids are selected for thermodynamic calculation. The results indicate that the evaporation temperature of double-stage ORC system affects performance parameters of system. Compared with single-stage ORC system, double-stage ORC system can improve net output power by 8.44% to 12.20%. The thermal efficiency of double-stage ORC system reduces maximally by 0.81%. The results also show that exergy efficiency is related to the type of organic working fluids. The organic working fluid flow in double-stage ORC is higher than that in single-stage ORC. When R601, R601a and R600 are used as working fluids, the required mass flow rate is small. The double-stage ORC system can effectively reduce the outlet temperature of heat source in the evaporator, ranging from 12.51 to 14.07â„ƒ.
Keywords Evaporation temperature, Net output power, Thermal efficiency, Exergy efficiency