To efficiently recover the waste heat from the diesel engine exhaust

an organic Rankine cycle (ORC) system was employed. The variation tendency of the diesel engine exhaust energy under various operating conditions was analyzed through experiments. Based on the particle swarm optimization

the operating parameters including evaporation pressure

superheat degree

and expansion ratio of ORC systems were optimized with net power output and exergy efficiency selected as objective functions. The optimization results show that

for a certain operating condition of the diesel engine

the optimal values for evaporating pressure

superheat degree

and expansion ratio can be determined. According to the optimization

the ORC system and vehicle diesel engine-ORC combined system are studied. The results show that

at the diesel engine speed of 2200 r·min-1 and engine torque of 1215 N·m

the net power output of the ORC system is 30.61 kW and the power output increasing rate of the combined system is 9.86%. At the diesel engine speed of 1200 r·min-1 and engine torque of 1131 N·m

the brake specific fuel consumption of combined system is 175.0 g·(kW·h)-1.