Performance and emission characteristics of a diesel engine with varying injection pressure and fuelled with raw mahua oil (preheated and blends) and mahua oil methyl ester

The present experimental investigation aims to depict the effect of varying injection opening pressure (IOP) using diesel-mahua oil (raw) blends as fuel on the characteristics of a small agricultural engine. The effect of preheated mahua oil and mahua oil methyl ester (MOME) as fuel on engine characteristics has also been investigated. Series of short-term tests were conducted on a single cylinder, 3.7 kW, water cooled, stationary diesel engine and performance and emission characteristics were determined using different diesel-mahua oil blends and also with varying IOP. Optimal IOP as well as blend ratio was determined for maximum efficiency and minimum emission values. Further, a novel pipe in pipe counter flow heat exchanger was designed and fabricated to arrange for preheating the raw mahua oil with exhaust gases of the engine. MOME was also prepared and tested as fuel in engine. Characterisation for major properties of all test fuels was conducted. Performance and emission characteristics of the diesel engine for raw mahua oil blends (unheated) at both rated and optimal IOP were compared with those of diesel, MOME and preheated raw mahua oil. At IOP of 226 bar, maximum brake thermal efficiency was obtained for M10, M20 and M30 blends. Significant reduction in carbon monoxide and hydrocarbon emission were observed. Nitrogen oxides emissions increased marginally. It was also observed that preheated mahua oil as fuel increases efficiency and reduces emissions. The use of M10 even at rated injection pressure and M20 and M30 at 226 bar results in minimum loss of efficiency and generates higher environmental benefits.