Application Research On Methanol And Diesel Blended Fuels In OPOC(Opposed Piston And Opposed Cylinder) Diesel Engine

With the development of society, the majority of families own the car gradually and the number of the cars is rising, followed by the increasing consumption of oil and the more serious environmental pollution. Therefore, saving energy and protecting the environment have become an important concern of the whole society. For the car engine, in addition to changing the fuel injection strategy and other conventional methods to improve the combustion and reduce emissions, the use of new clean pollution-free fuel instead of oil can effectively solve these two problems. Methanol is a clean alternative fuels the source of which is particularly widespread, it can promote the complete combustion of diesel engines and optimize emissions. Therefore, the application of methanol in the combustion of engine has become a hot topic in the field of internal combustion engines and has a good development prospect.Firstly, this thesis chooses the appropriate multidimensional simulation mathematical model. Then it establishes the 3D simulation model of OPOC diesel engine working process in AVL FIRE software, divides the grid by 3D simulation model, and establishes the appropriate boundary condition and initial condition.Secondly, this thesis chooses isooctanol as cosolvent and combines methanol with diesel which have the opposite polarity and they are difficult to dissolve at room temperature to the mixed fuel M5, M10 M15 which volume fraction of methanol is 5%, 10% and 15%respectively. Based on the research of numerical simulation, this thesis study the working process of methanol-diesel blended fuel with the different proportion in OPOC diesel engine.It studys the change of the injection process, combustion process, reactant concentration,pressure, temperature, heat release rate and emission concentration during different proportions of methanol and diesel blends combustion in OPOC diesel engine. It can be concluded that the ignition delay of the blended fuel is delayed with the increase of the proportion of methanol in the methanol-diesel blended fuel, the ignition time becomes longer,the maximum burst pressure and the maximum temperature increase in the tank and the heat release rate curve is shifted as a whole and the heat release rate increases, while the NOx and soot emissions decrease compared with the combustion of diesel(MO) in OPOC diesel engine.Finally, this thesis studies the process of spraying, burning and discharging in the OPOC diesel engine with M15 methanol-diesel blended fuel under the circumstances which fuel injection advance angle is different. It can be concluded that the ignition delay increases with the increase of the advance angle of the fuel injection. A lot of fuel gathers in the combustion chamber and the fuel is burned rapidly after the start of the combustion, so that the pressure inthe cylinder and the heat release rate increases, at the same time the mass fraction of NOx emission increasing with the increase of the fuel injection advance angle, while the soot quality fraction gradually decreases.