Study On Combustion And Emissions Characteristics Of A CRDI Engine Fuelled With Methanol-Diesel Blends

Internal combustion engine has been widely used in all walks of life, particularly inthe automobile due to its high efficiency, compact structure, good mobility, simpleoperation and maintenance. After a century of continuous development. Although themain performance, such as power, economy, reliability has reached a high level. Itsdevelopment is far from reaching the zenith, and the power, economy and emission alsoneed continuous improvement.In this study, Experimental investigation was carried on a common-rail directinjection(CRDI) engine with Methanol-diesel blends. Compared to the applicability ofthe different fuels, Without changing the original structure, and keep the engine in thestate of efficiency and low emissions.Firstly, ECU ran under the original data, through comparative analysis on thecombustion and emission characteristics of M0, M5, M10and M20: the maximumcombustion pressure, the peak heat release rate and the maximum combustiontemperature of the blends were gradually increased with the increase of methanol ratios.At the same speed and power output, the BSFC of M20was slightly higher than that ofM0, the BSFC of M5and M10was significantly lower than that of M0in the low andmedium load, they all decreased with the decrease of the load and tended to be close.The NOx emission decreased with the increase of methanol ratios and increase with theincrease of the load. The HC and CO emissions increased with the increase of methanolratios and decreased with the increase of the load.Secondly, under2000r/min/75Nm-225Nm and300r/min/75Nm-225Nm,experimental study on the influence of main-injection-timing of the combustion andemission characteristics: with the advance of main-injection-timing, the maximumcombustion pressure and the combustion temperature of the blends increased. Thevariation of the peak heat release rate and combustion duration with the advance ofmain-injection-timing was complex, which showed decrease with the advance od main- injection-timing in some individual conditions. The BSFC of the blends decreased withthe advance of main-injection-timing,it would increase with the increase of themethanol ratios at the same main-injection-timing. CO and HC emission both decreasedwith the advance of main-injection-timing, while NOx emission increased significantly.Finally, under2000r/min/225Nm,experimental study on the influence of EGR oncombustion and emission characteristics: with the increase of the EGR valve opening,the maximum combustion pressure of M0and M5increased, while that of M10andM20decreased, and the peak heat release rate of the blends decreased, the combustionduration extended, the maximum combustion temperature decreased. The BSFCincreased with the increase of the EGR valve opening, with the increase of the methanolratios, the BSFC deceased. The CO and HC emissions increased with of increase of theEGR valve opening, while NOx emission decreased significantly.