Research On The Characteristics Of Engine Exhaust Gas Based On The Recycling Of Exhaust Gas Energy

The recycling of the exhaust gas energy is one of the measures to improvecomprehensive utilization of fuel energy and to achieve energy reduction.However，theworking condition of vehicle engine is complicated，with a nonsteady characteristics，lead to the state parameters(pressure，temperature，flow rate，mass flow rate etc) of theexhaust gas presenting a transient volatility.The exhaust gas as the energy transmitter，its state parameters along with the variation of the engine working condition determinethe transient pulsation property of various energy of the exhaust gas，making recyclingprocess of exhaust gas energy relatively complex.For the rational use of engine exhaustenergy，the analysis of the characteristics of the exhaust gas is very necessary.Firstly，from the thermodynamics，using the energy balance method and the analy-sis of available energy method to evaluate the exhaust energy respectively.Meanwhile，analyses the losses condition of exhaust energy along the direction of the exhaust gasflow，and put forward the corresponding measures to reduce energy loss.Secondly，analyses the components of engine exhaust gas，according to the derivation method ofthe thermal physical parameters of the ideal gas mixture，obtains thermal physicalparameters calculation formula of exhaust gas.Finally，using an engine simulationsoftware GT-Power to establish a gasoline engine simulation model，through thesimulation calculation of the selected operating point，obtain the variation of the exhaustgas state parameter of each monitoring point under different working conditions.Onthis basis，use the Matlab software to program calculation of the exhaust gas energy toobtain the dynamic characteristics and distribution of the various exhaust energy.The results show that with the increase of engine load and speed，the kineticenergy，pressure energy and thermal energy of the exhaust gas is gradually increasing，and energy fluctuation intensity increases，has good pulsation；along the direction of theexhaust gas flow，the kinetic energy，pressure energy and thermal energy of the exhaustgas is gradually decreases，and the pulsation of exhaust gas is weakened；the thermalenergy account for the largest proportion of exhaust gas energy，especially at lowspeed，almost all of the exhaust energy is thermal energy，and the lower the load，thethermal energy to the greater proportion of exhaust energy；with the increase of thespeed，the proportion of kinetic energy and pressure energy increase relatively，but the increase rate is relatively slow，the proportion of the thermal energy reduce，but stillaccounts for most of exhaust energy；along the direction of the exhaust gas flow，theproportion of thermal energy is growing，the proportion of kinetic energy and pressureenergy reduce relatively.Overall，the potential of energy recycling is large，in the10cm away fromintersection of exhaust manifold，the exhaust available energy flow rate is65915.09J/s.The results of this study may provide reference data for the analysis of exhaustenergy recovery potential and mode selection to provide theoretical guidance for thesubsequent energy recycling research work.