Emission Comparison of Air-Fuel Mixtures for Pure Gasoline and Bioethanol Fuel Blend (E20) Combustion on Sparking-Ignition Engine

M.A. Muregi, M.S. Abolarin, O.J. Okegbile, E.J. Eterigho, I.P. Okokpujie

Abstract


This study analyses and compared the exhaust gas emission of two different airfuel mixture, Pure Gasoline and Bioethanol Fuel blend (E10 and E20), in a spark-ignition (S.I.) engine. Proximate and ultimate analyses of pure gasoline and bioethanol blend were carried out for their respective percentage (%) elemental composition for each fuel (i.e., carbon, hydrogen, oxygen, sulphur, nitrogen, metals, and water). The analysis reveals that pure gasoline has high carbon (C) content of 86%, and bioethanol has a carbon content of 52.2%. Oxygen content stands at 33-35% and was carried out at varying load conditions. To ascertain their CO., CO2, HC., NO, lambda, and the calorific values of exhaust emission. The result clearly shows that bioethanol's calorific value is lower than that of gasoline, which gives a remarkable increase in mechanical efficiency, which was attributed to an increase in the oxygen content in bioethanol, ethanol blend during combustion gives an airfuel mixture lean in an unmodified engine. Hence the mixture strength (charge) burns more rapidly. Bioethanol blends in gasoline engines reduce CO. emissions, unlike gasoline, which gave higher CO emissions. The gas emission test was conducted on E10, and E20.and effective combustion was determined and completed much earlier in the expansion stroke, thereby decreasing the probability of CO emissions due to flame quenching. At the end of the investigation, it was found that bioethanol blend reduces CO and HC in exhaust stroke by 40% and gives a higher compression ratio (high speed) thus, causes a decrease in CO2 NOX. E20 for both idle and high speed recorded a remarkable reduction in comparison. Therefore, bioethanol fuel blends in gasoline engines are recommended as mitigation against the greenhouse gas effect

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