Multi‐objective optimization of compression ratio and hydrogen flow rate in a dual‐fuel biodiesel engine

Abstract

Utilizing hydrogen as a CI engine fuel creates a pathway towards decarbonisation and its higher in‐cylinder temperature leads to an intensified thermal NO _x formation. To overcome this trade‐off, this study examines the combined effect of compression ratio, hydrogen flow rate, and oxygenated biodiesel blends in a dual fuel engine. Taguchi design methodology with Taguchi's orthogonal array ( L ₉ ) was adopted to design the test matrix, and the experiments were conducted as per the designed test matrix. Multi‐Response Signal‐to‐Noise (MRSN) ratio coupled with analysis of variance (ANOVA) methodology was adopted to investigate the optimum combination of factor levels and influence of the factors. ANOVA explored that the engine compression ratio dominates its control over NO _x (58%) and BTE (53%), while hydrogen flow rate (66%) manages its control over smoke as their percentage contributions are relatively higher than that of other factors. At the obtained optimized combination (12 lpm hydrogen flow rate, CA B20, and a compression ratio of 17.5), smoke opacity was relatively decreased by 13.4%, and the BTE was increased by 2.7%. This simultaneous improvement in smoke and BTE was achieved along with a marginal 8.9% NO _x trade‐off when compared with diesel.