Study On The Efficiency Of Working Fluid Pump In Organic Rankine Cycle System

In recent years,more and more scholars have conducted theoretical and experimental researches on the organic Rankine cycle technology.While the researches of working fluid pump is relatively rare.In this paper,the efficiency of the working fluid pump in the organic Rankine cycle system is studied.In this paper,the working fluid pump’s efficiencies are clearly defined,while the calculation method and the theoretical meaning of the efficiencies are also defined.According to the states of working fluid when it goes through working fluid pump,the working fluids’ saturated liquidus slope is studied and analyzed.The isentropic efficiency of the working fluid pump in a small-scale power system of organic Rankine cycle is experimentally studied under designed variable conditions,the selection and principle of the working fluid pump are focused,and a small-scale power system of ORC using R245 fa and R123 as working fluid is established,which its evaporation temperature is under 100℃,condensing temperature is under 20℃,and output power is lower than 10 k W.The results shows with the increase of mass flowrate of system and the pressure difference between the inlet and outlet of the working fluid pump increases,the isentropic efficiency increases,and affected by the mass flowrate is larger.Comparison of the experiments with R245 fa and R123 in the organic Rankine system,the working fluid pump using R245 fa has the higher isentropic efficiency,meanwhile,R245fa’s saturated liquidus slope is smaller than R123’s.The experiments confirmed the estimation efficiency of the working fluid pump in the Organic Rankine Cycle system is much lower than the previous value,and taking the experimental working fluid pump isentropic efficiency of the average value of 30% is more appropriate;from isentropic aspect,pump power for expander output power ratio of 8%,taking into account the actual process,considering the efficiency of the pump and the motor efficiency,the ratio should be greater than 12%.After exergy analysis of organic Rankine cycle system,while the isentropic efficiency of working fluid pump is low,the working fluid pump has great energy-saving potential.