Study On Performance Of Methanol-Hydrogen Engine With Different Blending Ratio

With the development of society,the internal combustion engine market continues to expand.At the same time,the issue of fossil energy security is becoming more and more serious.The environmental pollution caused by automobile exhaust is increasing day by day,posing a major challenge to the sustainable and healthy development of China’s economy.Therefore,finding a cleaner,more efficient new fuel has become one of the important research directions.Methanol is an ideal engine cleaning fuel.It has a fast burning speed and high oxygen content,which can effectively improve in-cylinder combustion.At the same time,it can recover engine exhaust energy to crack methanol and mix its cracking gas with methanol.Further energy saving and emission reduction.In this way,a 4-cylinder ignition gasoline engine was transformed into a methanol engine.A simulation model based on 3D CFD platform was established and calibrated by bench test.The combustion characteristics and thermal efficiency of the alcohol-hydrogen engine at different methanol cracking gas ratios were calculated and analyzed.The relationship between cracking gas and ignition timing,intake timing and EGR was also investigated.At the same time,the effect of methanol cracking gas on lean combustion and engine starting performance was studied.The results show:1.Under the condition of equivalent combustion,the speed and intake pressure are constant.As the proportion of blending is increased,the peak value of cylinder pressure,the peak value of heat release rate and the peak value of cylinder temperature are continuously increased,and the corresponding crank angle is continuously advanced.The cycle indication power of the engine is continuously decreasing.The power is degraded.At the same time,the optimal ignition advance angle is continuously delayed,the engine knocking tendency is increased.Under the same load,the indicated thermal efficiency₂ of the fuel itself decreases with the increase of the blending ratio,but the comprehensive indicated thermal efficiency₁ is obviously improved,and the highest is increased from 39.22%of the original machine to 41.26%,which is increased by 2.04%.2.Under lean conditions,the other parameters of the engine are not changed.With the increase of excess air coefficient,the peak value of cylinder pressure,the peak value of heat release rate and the peak value of cylinder temperature are continuously decreasing,and the corresponding crank angle is delayed.The flame development period and combustion duration are prolonged.However,with the increase of the blending ratio,the combustion performance is obviously improved,and as the blending ratio increases,the excess air ratio corresponding to the highest indicated thermal efficiency of the fuel itself is also increasing.In the state of excess air ratio of 1.5 and 80%of the blending ratio,it can reach 41.32%;while maintaining low NOx,HC and CO emissions.Therefore,a larger blending ratio is suitable for a deeper degree of lean combustion,which can achieve better combustion efficiency and good emission performance.3.Under the starting condition,as the proportion of blending increases,the peak value of cylinder pressure,the peak value of heat release rate and the peak value of cylinder temperature increase continuously,and the corresponding crank angle continues to advance.CO and HC emissions continue to decrease,NOx emissions Increased but kept at a lower level.Meanwhile,the formaldehyde emission reductions.