A comprehensive assessment of fuel reformulation strategies in Delonix regia biodiesel to improve CI engine characteristics with RSM optimization

The objective of this research was to examine how the performance and emission characteristics of a B20 blend of diesel and gulmohar biodiesel could be improved using two approaches: partial hydrogenation and the addition of di-tert-butyl peroxide. The ignition quality and emission characteristics of Delonix regia biodiesel are influenced by the proportion of polyunsaturated fatty acid methyl esters. Hydrogenated Delonix regia biodiesel was produced using a high-pressure autoclave reactor, and gas chromatography (GC) analysis was performed to quantify changes in fatty acid methyl ester composition, particularly the reduction of polyunsaturated components resulting from partial hydrogenation. Further, the experimental results were analysed using desirability function optimization in Design-Expert 13 software. The cetane enhancer, DTBP, was blended with B20 at a concentration of 2 ml/L. A diesel engine was used to evaluate the performance and emission characteristics of base diesel, GB20, HGB20, and GB20 + DTBP fuels. Compared with the GB20 blend, the modified GB20 fuels showed reductions in NOx emissions of 10.8% for HGB20 and 12.8% for GB20 + DTBP. In addition, the brake thermal efficiency at full load increased by 7.1% for HGB20 and 2.5% for GB20 + DTBP. Compared with diesel fuel, emissions from the modified biodiesel blend specifically carbon monoxide, HC, and smokes were significantly reduced. Moreover, improvements in CI engine performance were achieved through the development of a CCD model using response surface methodology (RSM). The desirability function yielded an accuracy value of 0.918 and identified hydrogenated GB20 at higher loads as the optimal operating condition. The investigation indicated that hydrogenated GB20 is the most advantageous blend among the tested fuels and can operate efficiently as a diesel substitute.