A Comparative Study on the use of Butyl Esters of Soyabean and Sunflower Oils as Biodiesel Fuel for Compression Ignition Engine

To study the feasibility of using two edible plant oils as diesel substitute a comparative study was made. Oils were exacted from the seeds of soyabean (Glycine Max, Family: Leguminoceae) and sunflower (Helianthus annuus, Family: Asteraceae/Compositeae). Oils were esterified (butyl esters) before blending with pure diesel in the ratio of 10:90, 15:85, 20:80, and 25:75 by volume. Pure diesel was used as control. Studies have revealed that on blending vegetable oils with diesel a remarkable improvement in their physical and chemical properities took place. Cetane number came to be very close to pure diesel. Engine (C.I.) was run at different loads (0, 4, 8, 12, 16, and 20 kg) at a constant speed (1500 rpm) separately on each blend and also on pure diesel. Studies have revealed that soyabean oil at 20% blend with diesel gave best performance in terms of low smoke intensity, emission of HC and NOx. All the parameters tested viz., flash point, total fuel consumption, specific energy consumption, specific fuel consumption, brake thermal efficiency and cylindrical peak pressure were improved. Results have further indicated that at 20% blend engine showed a closer performance to pure diesel. 20% blend of soyabean oil exhibited better performance than sunflower oil blends. However, both the oils at 20% blends with diesel can be used as a diesel substitute. There studies have thus indicated that esterified soyabean oil at 20% blend satisfies the important fuel properties as per ASTM D975 specifications of biodiesel as it lead to the improvement of engine performance and emission characteristics without any modification in engine.