Development And Simulation Of Key Components Of A Fuel System That Meets China ?

Since the 21 st century,the increasingly strict domestic emission regulations have focused on the control of vehicle exhaust pollutants,which has promoted the on-board engine technology and exhaust after-treatment technology to have a qualitative improvement,effectively controlling vehicle exhaust pollutant emissions.However,according to the statistics,in 2018,the number of gasoline vehicles using volatile fuels in China has accounted for nearly 90% of the total number of motor vehicles,exceeding 200 million,which has led to a more serious problem of gasoline evaporation.The newly implemented CHINA ? emission regulation has also imposed strict restrictions on the emission of evaporative pollutants from vehicles.Therefore,for gasoline vehicles,the development of a fuel system that can controls evaporative emissions,effectively recovers gasoline vapor,and meets CHINA ? emission standards is especially important.To this end,based on a certain vehicle,this paper starts with a fuel system that meets the CHINA ? emission regulation,and develops and designs key components of its fuel system,CFD simulation analysis of refueling characteristics,and evaporative pollutant emission tests.First of all,after studying a large number of domestic and foreign literatures,both the mechanism of gasoline vehicle evaporative emissions and the working principles,advantages and disadvantages of different gasoline vapor recovery technologies were analyzed.Then based on a certain vehicle,according to the relevant design requirements,this article designed a fuel system that meets CHINA ? emission standards,specifically,it explained the structure design,working principle,material and calculation of key parameters of key components of the fuel system such as fuel filler caps,Multi-Function Control Valve(MFCV),Inlet Check Valve(ICV),fuel tanks,activated carbon canister and filler pipes,and then,it also finished the layout of the fuel system and the allocation of evaporative emission limits.Furthermore,a three-dimensional unsteady gas-liquid two-phase flow model for the fuel filler pipe is established in this paper.Based on the fluid simulation software Fluent,aftering the realiability verfication and grid independence verfication of the model,this paper also simulated and analyzed the impact of the three key factors including the refueling speed of the refueling gun,the type of refueling gun(the depth of the refueling gun),and the radius of the first bend of the refueling pipe,which effect on refueling characteristics of the refueling pipe.The results show that in the case of the refueling speed 2.49m/s,3.07m/s,and3.73m/s,as the refueling rate increases,liquid seals are more likely to form in the filler pipe,but the vortex intensity of the oil at the outlet of the filler pipe will also increase,and the flow in the fuel tank will become more turbulent,which will lead to more gasoline vapor;compared with ZVA-Slimeline2 refueling gun(Insertion depth is105mm),when using OPW-12 VW refueling gun(Insertion depth is 80mm)to refuel,the oil liquid can not form a liquid seal in the filler pipe and is more likely to backflow and spray out from the filler pipe head,which will lead to refueling gun pre-mature shut off(PSO),and refueling gun like OPW-12 VW has higher requirements on the design of the filler pipe head;in the cases of the first bend radius of the filler pipe 70 mm,80mm,90 mm,100mm,110 mm and 120 mm,with the first bend radius of the filler pipe increase,the flow smoothness and the liquid-sealing performance of oil liquid in the filler pipe first improved and then deteriorated.Specifically,in the cases of the first bend radius of the filler pipe 70 mm,80mm,and 120 mm,the oil liquid in the filler pipe is more likely to backflow and gush out from the filler pipe head,and the liquid sealing effect is poor.Oppositly,in the cases of the first bend radius of the filler pipe 90 mm,100mm,and 110 mm,the oil liquid smoothly flow in the filler pipe without any refueling problems,and the liquid seal effect is good.Therefore,in order to ensure that the oil liquid can smoothly flow and effectively form the liquid sealing in the filler pipe.the first bend radius of the filler pipe should be 90 mm to 110 mm.Finally,the vehicle equipped with the fuel system designed in this paper was tested for both Evaporative Pollutant Emission(Type IV)and Refueling Process Pollutant Emission test(Type ?)of CHINA ?.The final pollutant emission values are 0.295 g and 0.012g/L,which are less than the limits of their respective test requirements and meet CHINA ? emission standards.