A Comparative Study of Exhaust Emissions Using Diesel-Biodiesel-Ethanol Blends in New and Used Engines

Abstract

The monoalkylesters of fatty acids derived from vegetable oils or animal fats are considered an attractive alternative fuel for diesel engines. This interest is based on a number of properties of biodiesel, including the fact that it is produced from a renewable resource and its potential to reduce exhaust emissions. Although several studies have been performed on biodiesel emissions, the results have been contradictory, with some studies reporting a reduction of nitrogen oxides (NOx) emissions while others report an increase. Adjusting engine parameters like exhaust gas recirculation (EGR), retarding injection timing, and using multiple injection strategies has reduced NOx to some extent. The objective of this study was to evaluate the effect on exhaust gas emissions of blending biodiesel and ethanol into conventional diesel fuel. Ethanol could be added to diesel in limited quantities along with biodiesel since biodiesel stabilizes the ternary system by acting as an amphiphile. This article illustrates the emission characteristics of diesel-biodiesel-ethanol (DBE) fuel blends on one used engine and two new engines. DBE is a new form of oxygenated diesel fuel blend and has the potential to reduce NOx emissions and to serve as an alternative to diesel fuel. The blend ratios (diesel:biodiesel:ethanol) by volume used in this study were 70:25:5, 70:20:10, and 70:15:15. The results with DBE showed a significant reduction in NOx emissions in new engines with increased ethanol concentration, whereas with the old engine under similar conditions, an increased NOx emissions profile was observed. CO emission increased with increasing ethanol proportion in the blends in both new and old engines.