Experimental Study On Fuel Injection Parameters Of Pressure Ignition Methanol Engine Assisted By Glow Plug

The pure methanol engine with electric plug can completely replace the traditional fuel with methanol,and its power performance is higher than that of the original engine.In terms of combustion,reasonable regulation of methanol engine fuel injection parameters can be accurately realize fully premixed combustion,namely homogeneous combustion,and can realize diffusion combustion,namely partial burning premixed heterogeneity,two kinds of combustion mode in such aspects as performance,fuel economy and emissions have different performance,under the different ways of burning fuel injection parameters of the various features of the engine influence also have differences,Therefore,this paper aims to explore the control strategy of engine fuel injection parameters in multiple combustion modes,and fill the theoretical blank of the influence of fuel injection parameters on various characteristics of methanol engine,thus providing theoretical and practical basis for the calibration of fuel supply and fuel injection system of pure methanol engine with electric plug combustion assistance.In this paper,a three-cylinder diesel engine was transformed into a pure methanol engine assisted by electric plug combustion.Through orthogonal test,the influence degree and influence law of each fuel injection parameter on the combustion characteristics of the methanol engine were studied.Then,based on the orthogonal test results: Under the single pre-injection condition,the main combustion modes in the cylinder were controlled by the electric plug combustion assisted pre-injection of methanol.The effects of different fuel injection parameters on the combustion characteristics,power and emission characteristics of the engine were studied and compared under the two modes of homogeneous combustion and heterogeneous combustion.Under the condition of multiple pre injection,the influence of pre injection strategy on methanol combustion characteristics was studied.The results show that each fuel injection parameter has a significant effect on the combustion starting point,and the most significant ones are the pre-injection pulse width and the main injection timing.The main combustion mode can be controlled accurately through the cooperation of these two parameters.In the homogeneous combustion mode,the main jet timing and the main jet pulse width have the most significant effects on the pressure rise rate.Rail pressure is the most significant factor affecting cycle volatility of methanol engine.For the selection of injection pressure,a compromise between power performance and cycle volatility should be considered.The combustion starting point is different for the best improvement of engine economy,cycle fluctuation rate and maximum pressure rise rate at each engine speed and large load,so the optimization of combustion starting point should be made by compromise among several objectives.Different injection parameters have different influence rules on conventional emissions under different combustion modes.In terms of CO emissions,in heterogeneous combustion,CO emissions decrease when pre-injection timing is advanced,main jet pulse width is reduced and injection pressure is reduced,while in homogeneous combustion,CO is almost not generated.In terms of NOx emission,increasing the pre-jet pulse width,postponing the timing of the main jet,increasing the width of the main jet pulse and increasing the injection pressure will improve the NOx emission under the heterogeneous combustion mode,while adopting the aforementioned regulation mode will worsen the NOx emission under the homogeneous combustion mode.Increasing the width of the main jet pulse and increasing the injection pressure can reduce HC emission under the two combustion modes.SOOT emission can be reduced by pre-injection timing and increasing injection pressure in both combustion modes.When the total injection pulse width is constant,the reasonable control of multiple preinjection injection strategy can improve the engine power performance,improve the engine cycle volatility,shorten the combustion duration,increase the combustion pressure,reduce the maximum pressure rise rate,make the combustion more gentle,and reduce the engine vibration and noise.