A multi-objective optimization model is built

which incorporates the net power output Wnet

exergy drop of exhaust fluid from inlet to outlet ΔEg

total exergy destruction rate I

and total cost C2013 of system into one function

and solved with the method of linear weighted evaluation function. Taking single working fluids R600a

R245fa

R601a and Pentane

and non-azeotropic mixed working fluids R600a/R601a

R245fa/R601a

R245fa/Pentane

and R600a/R245fa as examples

the evaporation temperature Te and condensation temperature Tc of subcritical organic Rankie cycle (ORC) are optimized. The results reveal that sometimes the optimal point can not be obtained using single-objective function

while it always can with multi-objective function. Moreover

the multi-objective optimization of ORC seems superior to single-objective optimization

because the multi-objective optimization coordinates the relationships among various performance indicators

which makes each indicator reach the optimal point as possible. Additionally

there exists optimal evaporation temperature Te

opt and condensation temperature Tc

opt minimizing the multi-objectivefunction F(X) values

but they vary with working fluids. For multi-objective optimization at Te

opt and Tc

opt

the comparisons of different single-objective function values and F(X) between non-zeotropic mixed working fluids and single working fluids show that the ORC performance of mixed working fluids is not always better than that of single working fluids.