Comparative performance and emission studies for vaporized diesel fuel and gasoline as supplements in swirl-chamber diesel engines

Abstract

An experimental study has been conducted to evaluate and compare the use of fumigated diesel fuel or gasoline as supplementary fuels for a naturally-aspirated, four-stroke diesel engine with a swirl-combustion chamber. The supplementary diesel fuel or gasoline is introduced together with the aspirated air (fumigation) in various proportions with respect to the main diesel fuel, which is injected in the usual manner. The influence of fuel/feed ratios (supplementary or main feed), for a large range of loads, has been examined on fuel consumption, pressure diagrams, exhaust smokiness and exhaustgas emissions (nitrogen oxides, hydrocarbons and carbon monoxide). Knocking limits have been determined. The differences in the measured performance and exhaust-emission parameters from baseline engine operation, when using either supplementary diesel fuel or gasoline fumigated in the intake air, are determined and compared. Our study shows promise for this approach and indicates that above ~60% of maximum load, there is high smoke reduction with only a slight change in specific fuel consumption, when using either one of the supplementary fumigated fuels. Examination of gaseous pollutant levels shows involved relations with respect to load and fuel proportions. Theoretical aspects of the supplementary fuel-mode (fumigation) of combustion are used to explain the observed engine behaviour.