Characteristics of Primed Methanol Fuels for Passenger Cars 831687
In addition to the use of volatile primers to provide methanol fuels with good cold starting characteristics, an additional component is needed for luminosity of methanol flames. Methanol fuels have been prepared with several volatile primers to provide improved cold starting characteristics. Dimethyl ether, which can be readily made from methanol, appears to be superior in several respects to other primers because it imparts adequate volatility at reasonably low concentrations and can tolerate water contamination without volatility changes or phase separation better than hydrocarbon primers. Hydrocarbon components have been identified that provide adequate luminosity to methanol fuel flames. Estimates of vapor flammability indicate that dimethyl ether primed methanol fuels can be made whose vapor is too rich to burn in confined tankage at least down to −20°C. The upper flammability temperature of isopentane primed methanol can be close to that of gasoline (−30°C), but the isopentane solutions are sensitive to water contamination. Primed methanol experiences greater volatility loss than gasoline during storage and use in vehicle tanks and carburetors. Greater evaporative emissions were also observed. Primers in the concentration range 0-15 volume percent appear to have no effect on octane quality in the CFR engine. Dimethyl ether seems not to aggravate methanol's preignition tendency.