Comparative Study On The Performance Of Engine Fueled With Gasoline And Methanol

With the rapid development of China's economy and society,the demand for automobiles in our country is increasing.Meanwhile,the problem of environmental pollution and energy crisis is becoming more and more serious.Our dependence on foreign oil is more than 65%.This is a great This is a great risk for energy security and sustainable development of national economy.The automobile consumes a large amount of petroleum resources,and automobile exhaust is one of the main factors that cause environmental pollution.It is one of the development direction of automobile engine to seek a cleaner and more efficient alternative fuel.The physical and chemical properties of methanol is close to that of gasoline,and its octane number is much higher than that of gasoline,which allows the engine to increase the compression ratio,s so as to improve the power and economy of the engine.The latent heat of vaporization of methanol is about 3 times that of gasoline,which can effectively reduce the temperature of the mixture,thus inhibiting the knock.Methanol has a wide range of sources and can be regenerated.It can be made through a wealth of coal resources.This is an effective way to solve the shortage of power fuel in China.According to the characteristics of methanol,the fuel supply system of engine is modified.According to the simulation results,in addition to the compression ratio of the original 9.5,the 11 and 12 are selected as the two compression ratio program.The characteristics of gasoline and methanol,and the effects of different compression ratios on the engine power,economy,combustion and emission characteristics are investigated in the way of bench test.The results show that the gasoline engine has improved its power and economy after burning methanol.When the engine is fueled with methanol and the compression ratio is increased,the pressure rise rate and the maximum explosion pressure in the cylinder are increased,and because of the high octane number of methanol,there is no need to significantly delay the ignition to suppress knocking.Therefore,even at a relatively large load,it is possible to maintain a high cycle thermal efficiency.When the engine is fueled with methanol,the emission of CO is almost not changed,the unburned HC is reduced by up to more than 90%,and NOx is significantly reduced at low load and slightly at large load.The compression ratio has a significant effect on the combustion characteristics of the methanol engine.When the compression ratio is 12,the engine energy consumption can be reduced by about 20% compared with the original gasoline engine,the maximum effective thermal efficiency is increased from 31.02% to 39.02%,the maximum torque is increased by a factor of 7.58%,and the maximum power is increased by 4.03%.It is necessary to delay ignition to reduce the mechanical load and heat load,which limits the further improvement of compression ratio.With the increase of compression ratio,CO emission decreased.When the compression ratio is increased to 11,the unburned HC emission decreases,but when the compression ratio is about 12,the HC emission is close to the compression ratio of 11.With the increase of the compression ratio,the NOx emission showed an upward trend,but the NOx emission was still lower than that of the original gasoline engine.