Experimental investigation on the performance characteristics and emissions of a CI engine fueled with enhanced microwave-assisted Karanja seed bio-oil

The main objective of the present research work is to utilise the produced bio-oil from microwave pyrolysis of Karanja, a non-edible seed, as fuel for diesel engines by increasing some up-gradation in the quality of the fuel. The emulsification process is carried out to improve the stability of the diesel-bio-oil blend using SPAN 80 and TWEEN 80, which lasted for 28 days without any layer separation termed as EKB20. The addition of 5% DEE and 10% DEE into EKB20 is done to enhance the combustion characteristics of the diesel engine. The produced bio-oil fuels were tested in a Kirloskar make, four-stroke, single-cylinder, direct injection diesel engine of 5.2 kW rated power output. The addition of DEE reduces the peak pressure by 4 bar and increases the heat release rate due to the higher volatility of DEE. At full load conditions, the thermal brake efficiency improved by 9.31% and 14.11%, respectively, compared to EKB20. Adding 5% DEE and 10% DEE at the rated power output reduced the smoke density by 18.42% and 60.25%, respectively, compared to EKB20 and 5% and 4% compared to diesel. The addition of 5% DEE and 10% DEE shows a 39% and 51% increase in NOX concentration and a 90% reduction in CO emission at the maximum brake power output. Hence, it is concluded that the fuels EKB20 + 5% DEE and EKB20 + 10% DEE can be used as alternative fuels for diesel engines.