Research On The Work Process Of High Compression Ratio Methanol Engine

The methanol has been studied for years as alternative automotive fuel, the research focus ona low compression ratio of the research is focused more on the gasoline engine and the mixturecombustion of diesel. than higher compression ratios of engine.It has high antiknock, so it issignificant to use the methanol in the higher compression ratios of engine to improvedperformance. The research is carried out this paper.The process of compact engine is carried out inthe engine based on the methanol engine retrofitted by the YD4A75-C3diesel. In this paper, thedetonation has been numerical simulation. by using software CFD, the reason and the position ofknock is studied with microcosmic respect. The reason of NOx formation is analyzed by thetemperature field of engine.The effects of control issue, ignition angle and EGR rate on theperformance of high compression ratio methanol engine are discussed.(1) Methanol has good antiknock property. It can avoid detonation by adopting reasonableignition angle under the traditional control method to make engine operate normally. The knocklimit of ignition angle retards with higher load. And it can be seen from simulations that the knockgenerally occurs far away from the region of the combustion center. Under this control method,torque increases at first then decreases with advance of ignition angle when the load is in the rangebetween25%and75%. Torque increases when ignition angle is advanced at full load. Themaximum torques of four loads occur at18°CA BTDC. Fuel consumption decreases as the loadincreases at the full range of operating conditions. At different loads, the three types of emissionsincreases along with advance of the ignition angle, while, HC and NOx increase with increase ofload at the same ignition angle, HC decreases with increase of load at the same ignition angle.(2) Under EGR without throttle control method，EGR is effective to inhibit the detonation,and broaden the ignition range of engine stable operation. Maximum and minimum EGR ratesincrease with advance of ignition angle. When ignition angle is42°CA BTDC, maximum EGRrate reaches50%. The range of the EGR rate at different ignition angles is different which results in different ranges of torque at different ignition angles. Overall, the range of torque decreaseswith advance of ignition angle. The engine can only operate in load range between50%and100%under this control method. Emissions at different loads increases with the advance of ignitionangle, at the same ignition angle, NOx increase with the increase of the load, however, HC andCO decrease with increase of load, NOx emission is lower due to the join of EGR.(3) The control issue of EGR/Throttle synthesizes the advantages of the first two models, andThe effects of ignition angle and throttle opening on the performance. At the load of50%, theTorque increases first and then decreases as the ignition angle increasing under the same throttleopening, and the same changes came as throttle opening increasing under the same ignition angle.At the load of75%, the Torque increases as the ignition angle increasing under the same throttleopening, and the torque decreases as throttle opening increasing under the same ignition angle.The effects of ignition angle and throttle opening on the emissions. At the load of50%,the CO、HC and NOx increases as the ignition angle increasing, NOx decreases as throttle openingincreasing, CO and HC increases as throttle opening increasing. At the load of75%,CO、HC andNOx increases as the ignition angle increasing, CO and HC increases as throttle openingincreasing, NOx decreases as throttle opening increasing.(4) To compare the minimum fuel consumption of three control issues, the minimum fuelconsumption at different road are optimized. The good compromise of minimum fuel consumptionand minimum emissions are optimized through minimum fuel consumption corresponding toemissions. Under the25%load,the engine is controlled normally by The traditional controlmethod, within the context of25%and100%load, the better performance can be got by Thecontrol issue of EGR/Throttle.