Analysis Of Influencing Factors Of Vehicle Fuel Evaporation Emission System And Improvement Design Of Carbon Tank

With the increase of car ownership in China and the improvement of global environmental awareness,people pay more and more attention to air pollution,energy shortage and other problems.With the promulgation of the sixth national standard,a new experimental study has been added in the standard--the emission test of fuel pollutants.The emission standard of automobile pollution has become more and more strict,marking that China's control of automobile pollution has entered a new stage.In the vehicle fuel emission control system has a crucial role is-carbon tank.This paper starts from the study of the vehicle fuel emission control system and the adsorption and desorption performance of the carbon tank,studies the changes of its internal flow field and temperature field,and provides simulation support for the improvement of the carbon tank design.This thesis introduce the mechanism of gas emission and emission control system,USES the time-varying diffusion model,establish the corresponding mathematical model of gas emission and the prediction model is compared with past experience model,based on the four kinds of mathematical model to calculate gas emissions,examining gas tank,Reid vapor pressure and temperature in the process of filling the fuel temperature three factors impact on the gas emission.By comparing the Matlab simulation results with the experimental results,the conclusion is drawn:with the increase of refueling temperature,Reid vapor pressure and tank temperature,the refueling emissions of gasoline cars increase,and the new prediction model can effectively predict refueling emissions.Ansys FLUENT software,using porous media model to simulate the actual jar carbon powder,according to the regulation of the six standards,to import the ford edge SUV activated carbon tank of petrol car simulation,simulation of the carbon in the process of absorption,stripping tank internal flow field of the flow characteristics,to obtain the pressure field,velocity,flow chart and the adsorption process are adsorbed butane transient simulation,get butane mass fraction distributions in the process of adsorption.The simulation analysis can obtain the flow details inside the carbon tank,and can also show the pressure distribution inside the carbon tank,so as to avoid eddy currents and regions with large pressure gradients in the structural design,and provide technical guidance for the structural design of the carbon tank.According to the testing requirements of ventilation resistance under thetechnical conditions in the national standard 6,the pressure difference between the adsorption port and the atmospheric port was measured,which was in accordance with the standards.Thus,it was verified that FLUENT software and the porous media model could be used to simulate the internal flow field of carbon powder with certain accuracy.After verifying that the software and the porous media model can accurately simulate the internal flow field of carbon powder,the mass conservation equation and the mass primary term,the energy conservation equation and the energy source term,the momentum conservation equation and the power source term of the porous media,and the d-a adsorption isotherm model are introduced.The user-defined project UDF in CFD software was used to write the required source terms and boundary conditions in c language.Through simulation,the temperature comparison of 6 different positions in the carbon tank body during the adsorption process was obtained,and the change curve of butane adsorption at 6 points was also obtained.It can provide a calculation method for the comparison of the adsorption performance of different carbon tank structures,and provide a basis for the performance analysis and design improvement of the subsequent carbon tank,which can greatly shorten the development cycle,improve the development efficiency and reduce the experimental cost.