To fully enhance the recovery and utilization rate of low grade source and lower the heat source emission temperature

a cascade heat exchange power generation system based on organic Rankine cycle(ORC) was proposed. With geothermal water serving as the heat source net power output as the objective function

this system's parameters were optimized by self-programed calculation algorithm using the REFPROP in Matlab

according to the first and second law of thermodynamics. Moreover

thermal performance of the system was analyzed by taking the non azeotropic mixture as the circulating working fluid

and the results were compared with the thermal performance of the basic ORC system. The results show that

under the optimal working conditions

the ORC-based cascade heat exchange thermal power system can effectively reduce the mean heat transfer temperature difference between the heat source and the working fluid

which results in less irreversible loss of heat transfer and a drop in the heat source emission temperature. When both the system adopt the selected working fluids

the thermal performance of this ORC-based cascade heat exchange power generation system is better than that of the basic ORC system

its net power output and exergy efficiencies can be increased by 16.07% at the most. When using R601/R236 ea as the working fluid

this ORC-based cascade heat exchange power generation system will achieve the optimum thermal performance.