The effect of compression ratio on the performance and emission characteristics of C.I. Engine fuelled with corn oil biodiesel blended with diesel fuel.

Abstract

The aim of this paper is to study the effect of changing the compression ratio on the performance and emission characteristics of single cylinder, 4-stroke compression ignition (CI) engine running with biodiesel and pure diesel fuel. Corn oil biodiesel blends were prepared viz. B5(5 %), B10 (10 %), B1 (15 %) and B20 (20 %) (by volume). The tests were performed at full load, constant speed 1500 rpm and different compression ratios 14, 15, 16, 17 and 18 %. The engine performance like brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and emissions of CO, CO2, HC, NOX and smoke opacity for all biodiesel blends were measured. The results showed that on increasing the compression ratios, the BTE increases and BSFC decrease for all types of fuel used, but it was found that for biodiesel blends B5, B10, B15 and B20, the BTE slightly decreased by 2, 4.2, 6.5 and 8.3 % and the BSFC increased by 3.3, 6.3, 9.4 and 13 % respectively, compared to the pure diesel fuel due to the high viscosity and density of biodiesel. With increasing the compression ratio and proportion of biodiesel blend, the emissions of CO, HC and smoke opacity were decreased, at the same time, the CO2 and NOX emissions were increased. The highest reduction in the emissions of CO, HC and smoke was found in the B20 biodiesel blend, which was 30, 26 and 23.8 %, respectively, while the same blend showed the highest increase in emissions of CO2 and NOX, which were 21 and 25.7 % respectively, compared to pure diesel fuel. Therefore, the biodiesel blend can be used at proportion up to 20 % and blend with diesel fuel in CI engines without any modifications.