This paper aims to evaluate the impact of cetane improvers on the combustion, performance and emission characteristics of a compression ignition engine fueled with a 20% peppermint bio-oil/diesel blend (P20). It is hypothesized that the low viscosity and boiling point of peppermint oil could improve the atomization characteristics of the fuel. However, the usage of peppermint oil is restricted due to its low cetane index. To improve this, Diethyl Ether (DEE) and Di- tertiary Butyl Peroxide (DTBP) are added to the P20 blend. The tests are performed in a single-cylinder naturally aspirated water-cooled diesel engine and results indicate that NOx emission for P20 + DEE and P20 + DTBP is decreased by 10.4% and 9.8%, respectively, when compared to P20 at full load condition. Among these two cetane improvers, DTBP is more effective in reducing the CO, HC and smoke emission and the performance of the engine was reported to be higher for P20 + DTBP blends.

This study experimentally investigates the performance, emission, and combustion characteristics of a nano-coated compression ignition (CI) engine fueled by Punnai biodiesel blends with varying proportions of ethanol. The nanocoating was applied to the engine's cylinder liner and piston crown to enhance heat transfer and reduce friction. The biodiesel blends were prepared by mixing Punnai oil with diesel fuel in various ratios (B20, and B30). Ethanol was added to each blend at 5% and 15% concentrations. This research desires to improve the operational efficiency of an engine that runs on diesel, through the utilisation of a piston coated with a thermal barrier, specifically tailored for punnai methyl ester blends. Thermal barrier coatings widely prioritise zirconia due to its exceptional thermal insulation properties. B20E15 has a brake thermal efficiency that exceeds that of diesel by around 3%. Similarly, B20E05 and B20E15 demonstrate fuel consumption reductions of approximately 3.8% and 16.3%, respectively. On average, the B20 blends exhibited a reduction in CO and HC emissions are 5% and 9%. A comparative analysis clearly demonstrated that nanocoated CI engines enhance performance and diminish emissions without any major modifications