ETHANOL AND METHANOL BLENDS WITH GASOLINE: AN EXPERIMENTAL APPROACH TO ENGINE PERFORMANCE AND EMISSIONS (ALCOHOL, BLENDS)

The effect of mixing methanol and/or ethanol with gasoline in fuel blends on brake specific fuel consumption, brake specific energy consumption, and exhaust gas emissions (CO, HC, and CHO) has been studied. Tests were conducted on a OEM 4-cylinder engine running at different conditions of equivalence ratio, spark timing, per cent of alcohol in alcohol-gasoline blends, and mixture of methanol and ethanol in the fuel. Results of this investigation indicated that fuel consumption increased as the percentage of alcohol was increased above 5% in an alcohol-gasoline blend. Fuel consumption also increased by 2 to 5% with retarded spark timings. Brake specific energy consumption was found to decrease by up to 8% with an increase of alcohol up to 15% in the blend. Minimum specific energy consumption was found to occur with normal spark timing and with equivalence ratios on the lean side of stoichiometric air-fuel ratios. No significant differences in brake specific fuel consumption or brake specific energy consumption were observed when different alcohols were used. Presence of alcohol in blend fuels were observed to reduce the concentration of carbon monoxide in the exhaust emissions (up to 40-50% compared to gasoline fuel). Minimum carbon monoxide emissions were observed to occur with equivalence ratios in the lean range (A/F ratios of 1 to 1.2). Methanol-gasoline blends were found to be slightly more effective than ethanol-gasoline blends in reducing CO. Hydrocarbon emission was also found to decrease by increasing the alcohol content of the fuel. Minimum HC production was found to occur with 10% alcohol-gasoline blends in conjunction with near stoichiometric air fuel ratios. Retard timing was found to cause increased HC by as much as 60%. However, Aldehyde emissions were found to be markedly higher with alcohol-gasoline blends. The percent alcohol-gasoline blends were found to provide 1 1/2 times the aldehyde emissions from pure gasoline.