Performance and emissions of gasoline–dual alcohol blends in spark-ignited single cylinder engine

Three alcohols (ethanol, methanol and isobutanol), two ethers (ethyl tert-butyl ether and methyl tert-butyl ether) and dimethyl carbonate were blended in a base fuel at 3.5 wt % oxygen. Two of the fuels were dual alcohol–gasoline blends with methanol/ethanol and methanol/isobutanol having the same added volume of each alcohol. The performance was analyzed on a single spark-ignited engine. Emissions of nitrogen oxides, carbon monoxide, unburned hydrocarbons and carbon dioxide were monitored online. The dual-alcohol blends present higher cooling effect, power and thermal efficiency as well as low combustion cyclic dispersion and fast combustion. Combustion effects due to the addition of oxygenates can be attributed to base gasoline dilution, for a given oxygen content. Also, dilution increases the hydrogen proportion, and this seems to have a strong relationship with the observed increases in combustion duration.