Modeling And Simulation Analysis Of Automobile Exhaust Energy Recovery System

Studies show that only 20%?45% of the energy released by burning car fuel is used efficiently,with the rest dissipated as heat.The energy carried by the waste gas accounts for about 28%?44% of the total energy dissipated,so the waste gas energy recovery is of great significance.Currently,the study of flue gas energy recovery system more focused on the mechanical aspects of engine and the power turbine,or is the whole modeling system but not fully consider the electromagnetic properties of permanent magnet synchronous generator,and the research of high speed permanent magnet synchronous generator,focused more on motor ontology not consider its application in exhaust gas energy recovery system.This thesis in view of the 94 kW diesel engine waste heat recovery and utilization of exhaust gas turbine power generation system,designed a 1.8 kW,60000r/min of high-speed permanent magnet generator,fully considering the engine speed,fuel injection advance angle,compression ratio and other parameters,the electromagnetic characteristics of power turbine speed and generator electromechanical coupling and influence each other relations,using GT-Power with MATLAB/Simulink and Ansoft software to establish model of the gas turbine power generation system as a whole.Firstly,the diesel engine and high-speed permanent magnet synchronous generator in the system are simulated and analyzed to the cylinder characteristics,speed characteristics,exhaust gas parameters characteristics of diesel engine and no-load and load characteristics of high-speed permanent magnet synchronous generator.The results show that with the increase of the rotational speed,the cylinder temperature of the diesel engine rises gradually,the pressure rises first and then decreases,and the torque increases first and then decreases,reaching a maximum of 402.42N·m at 1800r/min,and the power increases gradually,reaching 94.2kW at 2400r/min,and the exhaust parameters show an increasing trend.The magnetic density of stator tooth of high-speed permanentmagnet synchronous generator under no-load is about 1.5T,the air gap magnetic density waveform has good sinusoidal property and less harmonic,the voltage and current amplitude of the generator under load is about 68 V and 12 A,and the electromagnetic torque fluctuates around 180 m N·m.On this basis,the power generation effect of the system under the operating cycle of FTP-75 is further studied.The results show that the maximum power generation capacity of the system can reach 837 W and the maximum efficiency of the system is 39.3%.Based on this,further simulation analysis is carried out on speed,fuel injection advance angle,compression ratio of diesel engine,peak voltage,output power,efficiency of generator and their mutual influence.The exhaust parameters,economic and dynamic characteristics of diesel engine and the influence on generator performance are obtained: the peak voltage,output power and efficiency of generator show an upward trend when the engine speed increases,the fuel injection advance angle and the compression ratio decrease.Finally,the optimal working point of the system is given.