Effects of the ORC Operating Conditions on the Engine Performance for an Engine-ORC Combined System

Exhaust waste heat recovery by Organic Rankine cycle (ORC) systems has been proven as an effective way to improve thermal efficiency of engines. The performance of a diesel engine with an ORC system was evaluated in this paper. Both of the engine and the ORC system model were built in GT-SUITE respectively, and the two models were integrated in Simulink environment. The effects of operating conditions of the ORC system on performance of the engine in the combined system were discussed. The performance of the combined system with different inlet temperature of cooling water was also evaluated. The simulation results show that the engine backpressure increases with the decrease of the pump speed and the expander speed. The maximum engine power output increment at the engine speed of 1500 r/min and 2100 r/min is 5.47 kW and 7.07 kW respectively. The backpressure increment of the engine with ORC system increases with the increasing of cooling water inlet temperature.