Comprehensive Performance Evaluation Of Organic Rankine Cycle And Working Fluid Selection

Based on the indexes of work ability,economy and irreversibility of the organic Rankine cycle(ORC),a comprehensive evaluation model with Analytic Hierarchy Process(AHP)was built in this paper.Comprehensive evaluation index F and location function F1 were deduced by considering the effect of personal consideration on optimization.The optimal operating point was obtained by optimizing F1 and then the value of F could be determined.Coefficient of Variation(CV)was selected to evaluate the stability of the cycle.CV could reflect the fluctuation of F with external conditions' variation.The evaporation temperature and heat source temperature optimization were calculated by F for working fluid R227 ea.The comparison with the optimization result by net output power proved that F is more reasonable.The comprehensive performance of seven pure organic fluids was studied and the effect of weight W1 on the performance was considered.This paper also investigated the comprehensive performance of mixed fluids of R245fa/R152 a and made the comparative analysis with the pure fluids.Results show that the optimization result by F is more reasonable than that by net power.R245 fa,R600a are recommended as the best fluids at W1=0.5870,W2=0.3324,W3=0.0806 while heat source temperature ranging from 70 to 150?.The optimal heat source temperature of R143 a,R1234yf,R134 a,R227ea and R152 a are existed,which is related to the critical temperature of the working fluids.The comprehensive performance of pure fluid is better than the mixture fluid.