Characteristics Of Methanol Discomposed By Heat And Its Application To A SI Engine Electronically Controlled

As the economy of our country is developing rapidly, quantity of cars increasesrapidly year by year, making energy and environment face enormous challenge andpressure. Energy conservation and emission reduction become two serious problems,which scholars and experts of internal combustion engine must face. For this purpose,seeking new fuels to substitute fossil fuel is only way to solve problem of energy andenvironmental crisis. Alcohol as substitute fuel has a promising prospect in manysubstitute fuels.Liquid methanol as fuel of engine has many disadvantage, such as higherconsumption, difficult starting, lower combustion efficiency and higher emission.For solving this, American scholar proposed a new style combustion method: takingadvantage of exhaust heat and catalyst activity, liquid methanol dissociated intodissociated methanol gas, then sent into cylinder of engine as fuel. Althoughdomestic and overseas scholars did many researches about dissociated methanol gasengine, all prototype engines were based on carburetor engine, or adopted to makegasoline and dissociated methanol gas mixture as fuel for engine. And performancesof engine fueled with dissociated methanol gas were studied shallowly. In order tomake methanol dissociated gas apply on the electronic controlled sprayed enginepopularized widely, engine starts adopting gasoline as fuel and then switches to themodel that engine is fueled with methanol dissociated gas, when exhaust heat candissociate enough methanol dissociated gases to combust in cylinder.In this study, Cu-based catalyst and Pd-based catalyst were used to catalyzemethanol to become mixture gas of methanol dissociated under the condition of hightemperature. Methanol dissociated gas is mixture gas containing mainly hydrogen,monoxide carbon and gaseous methanol, and it components vary as the temperaturevaries. In order to clarify the effect of temperature on component of methanoldissociated gas, the bench was designed and constructed and GC was used to test thecomponent. Reaches results indicated: methanol dissociated gases contain mainlyhydrogen and methanol vapor, furthermore including partly monoxide carbon,methane and water etc. The effect of two types catalyst of Cu-based catalyst andPd-catalyst on components of dissociated gas and each component content is larger.With catalytic action of Cu-based catalyst, the value peak of volume fraction of H2shows up at higher environmental temperature. Volume fractions of CO and CH4keep a low level at all of operation tested, those values below3.0%; Whenenvironmental temperature is at250oC, volume fraction of water rapidly drops astemperature rises, and volume fraction of water being lower than5%at mostoperation tested; The minimum value of volume fraction of methanol vapor showingup reach4%at the environmental temperature range of400-450oC. With catalyticaction of Pd-based catalyst, there are two value peaks of volume fraction of H2attwo temperature areas, respectively300oC and500oC; Volume fraction of CO andCH4keep a low value; Value peak of volume fraction of water shows up at350oC;The minimum value of volume fraction of methanol vapor shows up at thetemperature of350oC and450-500oC.On the base of above the experimental results, the economic, power output,combustion in cylinder and emission performances of engine fueled with dissociatedgases that were produced from liquid methanol under catalyzed action ofrespectively Cu-based catalyst and Pd-based catalyst were studied deeply. Resultsindicates: the output performance of engine fueled with dissociated gas withCu/Pd-based catalyst can reach to95%or higher of that of prototype engine fueledwith gasoline; equivalent fuel consumption ratio of dissociated gas engine is betterthan that of gasoline engine, decreases by24%; maximum valvesof pressurecombustion in cylinder of dissociated gases with action of Cu-based catalyst andPd-based catalyst promote respectively6.2%-14.3%and10.5%-21.5%; meanwhile,heat release rate of dissociated gas is higher than that of gasoline, and dissociated gaswith Pd-based catalyst has the highest heat release rate; while coefficient of cyclicvariation(COV) of dissociated gas engine increases slightly in comparison ofgasoline engine; main combustion duration of dissociated gas in cylinder becomesshorter than that of gasoline, with dissociated gas under Cu-based catalyst andPd-based catalyst shortened respectively by4.8%and7.1%; using after treatmentonly with primary Three Way Converter, HC and CO emission of dissociated gasengine is about10%of that of gasoline engine, NOXemission is only20%.Compared with dissociated gas engine with Cu-based engine, the engine fueled withdissociated gas with Pd-based catalyst has better performances, and the dissociativeactivity, reliability and adhesiveness characteristics of Pd-based catalyst also arebetter than those of Cu-based catalyst.In this study, the experiments results of characteristics of components of dissociated gas varying as the temperature varies and performances of dissociatedgas engine can provide favorable technical supports and distinct technical route formethanol combusting efficiently and clearly on internal combustion engine.