Combined influence of compression ratio and EGR on diverse characteristics of a research diesel engine fueled with waste mango seed biodiesel blend

Currently world is encountering crisis such as diminution of fossil fuel resources and global warming due to engine emissions. Changing the operating parameters of the engine is one of feasible technique to enhance the engine performance. The present experimental work is mainly focuses on the influence of changing compression ratio along with different EGR rates for the research diesel engine fueled with 20% mango seed methyl ester (MSME 20).Transesterification process was used to reduce the viscosity of mango seed methyl ester. As per ASTM standards, the fuel properties of MSME and MSME20 were evaluated and compared with diesel. Initially, the compression ratio was varied at three levels such as 18:1, 20:1, and 22:1 for the diesel engine powered with 20% mango seed biodiesel blend and compared with diesel. Based on experimentation, it was found that MSME20 blend with compression ratio of 22:1 was shown enhanced brake thermal efficiency by 7.4% and also reduction in engine emissions such as carbon monoxide, hydrocarbon and smoke opacity by 33.3%, 40%, and 7.1% were found at full load respectively when compared to MSME20 with compression ratio of 18:1. However, there was considerable increment in NO(X)emissions. In order to mitigate the NO(X)emissions, the engine is further operated with different EGR rates (5% and 10%) at compression ratio of 22:1. The test results evident that addition of 5% of EGR to the engine running at compression ratio 22:1 reduced the NO(X)emission levels by 40.5% over standard conditions without much penalty in engine performance.