Research On Waste Heat Recovery System Of Gasoline Engine Based On Ranking Cycle

The widespread use of power machinery has aggravated the consumption of oil in the world,which brings the energy crisis and environmental problems.Energy conservation and environmental protection as an important issue has aroused widespread concern around the world.About 1/3 of the energy fuel released is effective in the form of work,and another third is consumed by the exhaust.The technology of waste heat recovery can recycle energy from exhaust effectively and improve the energy utilization rate,which has certain significance for reducing the consuming of energy source.This paper carries out simulation and experimental research on waste heat recovery of gasoline engine based on Rankine cycle.On the research of exhaust waste heat recovery by using Rankine cycle,a type of evaporator with multi-layer spiral tubes is put forward and used in the research.A mathematical model is generated to evaluate the performance of the evaporator.Based on the model,start-stop parameters each heat transfer section is analyzed.The simulation results show that the increases of the mass flow rate of the working fluid can lead to a reduced outlet temperature of working fluid and exhaust while an increased exhaust energy utilization rate.The heat transfer area will limit the increases of the mass flow rate and temperature of the working fluid.Expander is a key work component of Rankine cycle system.Compared with turbine expander,reciprocating piston expander is more suitable for waste heat recovery of engine.In order to study the porting timing of piston expander,the mathematical model of the thermodynamic cycle process of reciprocating piston expander is established,the impact of porting timing on the performance of the expander is then analyzed.The simulation results show that selecting the suitable porting timing can optimize the performance of the expander,and raise the efficiency of Rankine cycle.In addition,there is an increment of 1300 W power only by selecting an optimum porting timing.Considering the characteristics of the transient state of the gasoline engine,the flow rate of the working fluid and the speed of the expander are analyzed with the gasoline engine operating conditions to find out the best matching relationship.The experimental system,the test principle and control strategy are introduced in detail.Verifying the correctness of the model by the comparison between the theoretical and experimental results,laying a theoretical foundation for further analysis and optimization of Rankine cycle waste heat recovery system.