Simulation And Experimental Study On Waste Heat Recovery Of Gasoline Engine Based On Rankine Cycle

The engine exhaust energy accounts for about 35% of total fuel energy.If this energy is well recovered from Rankine cycle,it is an effective way to realize energy saving of automobile engine.This paper carries out simulation and experimental research on waste heat recovery of gasoline engine based on Rankine cycle.Gasoline engine model was built in GT-Power.Based on this model,the gasoline engine waste energy and available energy are analyzed.The research shows that the heat of the exhaust gas is equal to the output power of the gasoline engine,and more than 46% of the exhaust energy can be used.Considering the efficiency of recovery system and miniaturization of the equipments,water is chosen as the Rankine cycle working fluid.Indicators are put forward to evaluate system performance.The theoretical model of the single valve expander is established in Matlab/ Simulink software for its performance simulation.The structural parameters(expander diameter,stroke and relative clearance volume efficiency),operating parameters(intake pressure,intake temperature and speed),and gas distribution phase(intake valve lift and width and height of outlet window)are analyzed to find the relationship with expander output power,efficiency,and mass flow rate.The Rankine Cycle test system for a gasoline engine is established to recover the exhaust energy.The results of the experiment show that the speed of the expander is 1352r/min-1978r/min,and the output power is 2.06 k W-3.47 k W at different operating conditions.When the gasoline engine at the speed of 5500r/min,the power of 76.6k W,the maximum pressure of expander can reach 6.69 MPa,and the indicate power can reach 5.06 k W.The total efficiency of the Rankine cycle is more than 10% and the gasoline engine power increases by 5.8%.Output power per liter is used to evaluate the work capacity of single valve expander.Output power per liter of single valve expander reaches 35.3k W/L,meeting the requirement of miniaturization of the system.Theoretical analysis and experimental results show that the single valve expander is suitable for small flow,low power applications because of its small size,simple structure.It can be applied to engine waste heat recovery system based on Rankine cycle.