Experimental Investigation Into Combustion Characteristic Of Methanol Applied To Engines

The tests were carried out on the experimental test bench using different-contentof methanol-gasoline blended fuels on SI engine and a dual fuel DMCC concept onDI engine, which investigated the effect of methanol content and intake temperatureon the combustion characteristic, emissions and economy performance.The effects of methanol–gasoline (M0, M15, M50) fuel blends on the combustioncharacteristics, unregulated emissions and fuel economy were investigatedexperimentally and compared on a4-cylinder line gasoline engine without anymodification under the operation of European test cycle(urban road condition andhighway condition). The results show that peak cylinder pressure increases with theincrease of methanol content, while the relevant crank angle comes earlier. Themaximum heat release rate is higher than that of pure gasoline, combustion interval isshorter and cycle-to-cycle variation decreases. Non-burnt methanol and formaldehydeincrease with the increase of methanol proportion, first increase and then decreasewith the increase of load, and both of them reach zero emission after catalyzed byTWC. Equivalent fuel consumption rate of blends is lower than that of gasoline undermedium and high load, the maximum drop reaches9.0%at high speed and high load.Dual fuel combustion characteristics and performance of different quantity ofhomogenous methanol charge which formed at the intake manifold then ignited byminimum diesel fuel content in the cylinder was investigated at two different speedson a six-cylinder turbocharged and intercooled testing diesel engine. The testingresults indicates that，with the increase of methanol substitute rate, the ignition delayperiod of DMCC increases first, then decreases at high load. The peak heat releaserate of premixed combustion phase increases and stays at the maximum constant. Theportion of premixed combustion phase increases while the portion of the diffusivecombustion phase decreases remarkably. Compared with conventional dieselcombustion it was found that DMCC results in a higher peak cylinder pressure, singlepeak and rapid heat release rate under experimental operating conditions. It can beseen that volume combustion in space and the pattern of HCCI are presented in theheat release of high speed and high load. DMCC results in a CO and HC increase by nearly two orders of magnitude but they can reach conventional diesel engine levelusing DOC after-treatment,8~23%lower NOx,82~90%lower soot and2.3per centhigher gross indicated efficiency can be achieved. To help understand the effect ofintake temperature on combustion characteristic of dual fuel, three fuel flow rate wereused, it was found that the combustion phase becomes earlier with the increase ofintake temperature, methanol/air mixture self-ignition appears when temperatureexceeds70℃, NOxand smoke also increased with the temperature, there was amaximum indicated efficiency under an optimal intake temperature, which decreasewith the increase of engine speed.