COMBUSTION ANALYSIS AND STUDY ON SMOKE AND NOX EMISSIONS OF DIESEL AND BIODIESEL FUELED CI ENGINES WITH ETHANOL BLENDS

Diesel engines suffer from high amount of soot, particulate matter and nitrogen oxides emissions in spite of their advantages such as high thermal efficiency, low CO and HC emissions. The use of Biodiesel in conventional diesel engines results in a substantial reduction of HC, CO and PM. Its higher cetane number improves the ignition quality. However it suffers from cold starting problems and increased NOx emissions when compared with diesel fuel. Reduction of NOx emissions and particulate matter simultaneously is quite difficult due to the Soot/NOx trade off. In this investigation, tests were conducted on a single cylinder DI diesel engine fueled with neat diesel and biodiesel as baseline fuel and addition of 5 to 20% ethanol on a volume basis in steps of 5 vol.% as a bio-resource supplementary oxygenated fuel to analyze the combustion and emissions characteristics. The results have shown a simultaneous reduction of NOx and smoke emissions in comparison with baseline fuels. A global overview of the results has shown that the 15% ethanol addition to diesel and biodiesel fuel produce the lowest smoke opacity. Meanwhile the lowest amount of NOx emissions belongs to the 10% and 15% ethanol addition to diesel and biodiesel respectively.