Performance Analysis of Organic Rankine Cycle with Multi-stage Gas-liquid Booster Pump

Considering that the working fluid pump consumes a large percentage of the energy generated by the expander in organic Rankine cycle (ORC), this paper proposes to use a multi-stage gas-liquid booster pump which uses the vapor generated in evaporator to pressurize the working fluid in ORC. The performance of ORC with the various evaporating temperatures are compared when multi-stage gas-liquid booster pump with different stages and electric driving pump are used. Also compared are the effects on the performance of multi-stage gas-liquid booster pump from evaporating temperature, and the influence on the system performance from the pump efficiency. The results show that the net power of ORC equals to the power generated by expander when the multi-stage gas-liquid booster pump is used. The thermal efficiency of the system is improved with the increase of pump stage. The pump efficiency decreases with the increase in evaporating temperature, while increases with the increases of pump stage. With evaporating temperature of 145℃ and condensation temperature of 35℃, the system ' s net power and thermal effi- ciency are 25.8 kW and 0. 106, respectively, when the electric driving pump is used, and they are improved to 33.2 kW and 0. 120, respectively,when the four-stage gas-liquid booster pump is used.