A comparative study on influence of fuel additives with edible and non-edible vegetable oil based on fuel characterization and engine characteristics of diesel engine

Abstract

Use of vegetable oil as compression ignition engine fuel has been investigated by many researchers during last decade either by direct blending with diesel or converting it into bio-diesel but very few publications available regarding its direct use in engine. The direct use of straight vegetable oil leading to formation of injector deposits which in turn produces higher exhaust emissions. Fuel improvement through additive is an attractive option in existing diesel engine without any modification to meet worldwide legislative efforts to lower airborne pollution. Hence, use of locally available vegetable oil with addition of fuel additive in existing diesel engine becomes an indispensable tool in global trade to meet ever-tightening pollutant emissions regulations for heavy-duty diesel engine. This paper intends to compare the behaviour of edible and non-edible crude vegetable oil on engine characteristics of existing diesel engine under similar operating condition with cognitive elaboration. The main purpose of the present work was to investigate how commercially available fuel additives for diesel fuel, influence the edible and non-edible vegetable oil, by comparing the combustion, emission and performance characteristics under similar operating condition. A comparative study was carried out on Cummins two cylinder DI diesel engine at constant speed by varying brake load. The Sunflower oil (SF) was selected as edible oil and Karanj oil (KO) as non-edible oil whereas two commercially available fuel additives for diesel referred as ‘A1’ and ‘A2’ respectively in this study were procured for test trial. The experimentally obtained results revealed that both edible oil (SF) and non-edible oil (KO) showed longer ignition delay which in turn leading to higher cylinder pressure, HRR, higher NOx and CO emissions whereas showed lower BSEC and smoke opacity as compared to diesel fuel. However, the KO oil exhibited lower NOx and CO emissions when compared to SF while maintaining marginal difference in thermal efficiency. The test results showed that both additives were found effective in reduction of ignition delay, HRR and NOx formation with KO whereas increased NOx and CO emissions with SF. The additive A1 significantly reduced CO and smoke emissions with KO while the opposite trend was observed when additive A2 was used.