In order to utilize gasoline engine waste heat more efficiently

the waste heat recovery potential of a gasoline engine was studied. A model of gasoline engine-Rankine cycle waste heat recovery system based on evaporator and expander was established. By using the genetic algorithm and considering the output and adiabatic efficiency of the expander

the exhaust availability and evaporator efficiency

the optimum operating parameters of the system under four engine operating conditions were optimized with the output power of the expander and the total system efficiency as optimization objectives

the evaporation pressure and expander speed as optimization variables. The results show that the maximum exhaust utilization rate is higher than 46% in the whole engine speed range. The exhaust quality increases with the speed. Under different working conditions

there are the optimum expander speed and evaporation pressure. After optimization

the power under the four selected working conditions is increased by more than 6%

the highest up to 7.08%.