Effect of alcohol blending on real driving emissions of particulate matter from ordinary gasoline automobile engines: a comparison of ethanol, n-butanol and isobutanol

This paper summarizes the recent and ongoing work on real driving emissions of several automobiles with ordinary, non-flexible-fuel spark ignition engines, powered by alcohol-gasoline blends with higher concentrations of ethanol, n-butanol and isobutanol. On a Ford Focus automobile with a direct injection EcoBoost engine, powered by gasoline and its blends with 15% ethanol, 25% n-butanol and 25% isobutanol, particle size distribution were measured with an on-board fast mobility particle sizer along a 55 km route. Particle emissions were moderately reduced by ethanol and considerably by both butanol blends. On a Śkoda Fabia and Śkoda Felicia cars with indirect injection engines, powered by blends with higher concentrations of ethanol, n-butanol and isobutanol, particle emissions measured by a miniature on-board system were examined over a 13 km route. Blends of 30% and 50% of butanol had no or slightly positive effect on particle emissions. Blends of 70% ethanol and 85% n-butanol and 85% isobutanol, used with an auxiliary engine control unit, had no or slightly positive effect on particle mass, and reduced total particle length (roughly corresponding to lung deposited surface area) by about one half.