Simulation And Test Study Of Combustion And Emissions Of SI Engine Fueled With Methanol Gasoline

Methanol gasoline, as an alternative fuel of engine, can ease the shortage of oil resources, but also increased the unregulated emissions due to the added methanol component and its degree of harm should not be overlooked. This study is based on the National Natural Science Foundation project-the generated mechanism and optimization study of the control of unconventional pollutants and emissions using SI engine fueled with alcohol-gasoline blended fuel, aims at the emissions characteristics of the engine when mixed different proportion of methanol through numerical simulation and bench test.First, without any changes done on the engine, we undertook the engine test of the emission performance of the methanol gasoline mixed fuel with different ratios and measured the composite in the emission using AVL-FTIR Fourier transform infrared spectrometer. The results indicated that the emissions of formaldehyde and unburned methanol increase with the increasing ratio of the methanol in the mixed fuel, while the aromatic hydrocarbons (AHC) decrease at the same time. With the increasing of the load, the emission of unburned methanol, ethanol and AHC increase a little bit, while formaldehyde first decreases and then increases. Furthermore, the mixing ratio of the fuel has a strong influence on the transformation ratio of formaldehyde by the catalysts. The transformation ratios are relatively higher when the portion of methanol is lower than30%, which is over85%. And the ratio is low when the portions are higher than50%, which is40%as a minimum. And it is highly depended on the conditions of the engine as well, which increases with the increasing of the engine speed and torque. As for the unburned methanol, ethanol and AHC, the catalysts have a satisfactory transformation ratio on them.Secondary, the chemical reaction mechanisms of methanol and isooctane were simplified. Boost and the Chemkin software were used to get coupled simulation. The simulation model of engine using gasoline mixed with methanol was built. The model is validated based on experimental data. Then, using the built engine model, simulate M50and MO in2000r/min, full throttle conditions. The simulation results show that using M50fuel, the gasoline engine output power decreased by approximately14%compared to MO. In addition, Do the simulation optimization by increasing the compression ratio, adjust the ignition advance angle to the gasoline engine fueled with M50methanol gasoline. Results show that, M50, in2000r/min, the throttle fully open condition, increasing the compression ratio of the engine output power can be increased, while reducing CO emissions but NOx, HC, and formaldehyde emissions increase; adjust the ignition advance angle can increase engine power while reducing CO emissions, but NOx, HC, and formaldehyde emissions will rise.