Influence of hydrogen enrichment and piston geometry modification on diesel engine performance, emissions, and vibrations powered with Juliflora biodiesel

Abstract The present study evaluates the combustion behavior, vibration response, performance and emission parameters of a diesel engine using with conventional diesel, a 20% Juliflora biodiesel blend (JUB20), and JUB20 supplemented with hydrogen at a constant flow rate of 8 lpm. Piston geometry was modified in an engine with SSVP and SSCVP and compared against the standard piston. Juliflora biodiesel (JUB20) was optimized using machine learning (Random Forest) technique by considering reaction temperature, methanol‐to‐oil ratio, reaction time, and catalyst concentration, and fuel properties were measured as per ASTM standards. Initially, engine tests were conducted with diesel and JUB20 fuel but we observed a lower BTE with biodiesel blended fuel then induction of hydrogen gas through inlet manifold was carried. Next, conventional piston was replaced with two altered pistons such as SSVP (Symmetrical Spline‐V piston) and SSCVP (Symmetrical Stepped Curved‐V piston) to conduct engine tests using JUB20 fuel with and without hydrogen gas. The highest BTE was recorded with JUB20 + HYD + SSCVP fuel that is. 9.82% compared to JUB20 fuel and lowest BSFC that is, 21.62% was obtained at peak load condition. Enhanced combustion efficiency was observed with hydrogen and a redesigned piston, attributed to the enhanced turbulence and homogeneity in the air–fuel mixture. Emission parameters such as CO, CO 2 , and HC were drastically reduced with hydrogen addition and piston modification. This combined technology enhanced combustion efficiency but showed a marginal rise in NOx emissions. Vibration tests were conducted to evaluate engine amplitude. Comparisons were made across all fuel samples.