Response Surface Methodology-Based Optimization of Injection Timing and Hydrogen Flow in an Mahua Biodiesel–Hydrogen Dual-Fuel Engine

Abstract

Investigations on alternative diesel engine fuels have intensified due to the growing demand for cleaner energy sources. This study adopts a novel methodology by examining the performance, combustion, and pollutant emissions of a single-cylinder, four-stroke variable compression ratio engine fueled by an M25 biodiesel-hydrogen dual-fuel blend, with optimal injection timing in conjunction with hydrogen enrichment. The subsequent injection timings and hydrogen flow rates evaluated were IT21, IT24, IT27, and IT30 degrees prior to TDC. Under full load conditions, IT30 operating with a hydrogen flow rate of 16 lpm attained a minimum brake-specific fuel consumption (BSFC) of 0.28 kJ/kWh and a maximum brake thermal efficiency (BTE) of 32.7%. The experimental settings elevated the cylinder pressure by 11.7 % and the heat release rate by 8 % relative to usual operation. The emission investigation results indicated a 54% reduction in carbon monoxide (CO), a 24.7% reduction in hydrocarbons (HC), and a 37.2% reduction in smoke opacity; nevertheless, due to elevated combustion temperatures, NOx emissions increased by 7.2% to 820 ppm. The ideal working condition, as determined by Response Surface Methodology optimization is IT30.25˚ and 16 lpm H2. This design forecasts a BTE of 32.52% and NOx emissions of 790 ppm. Statistical validation was accomplished by diagnostic methods, and this study introduces an innovative methodology that combines biodiesel combustion enhancement with meticulous regulation of hydrogen flow and timing adjustments. M25-hydrogen blends demonstrate potential as a viable decarbonized engine technology, with a performance-enhanced approach to satisfy BS-VI and Euro VI standards