Evaluating the performance, combustion, and emission characteristics of decanol-enhanced sterculia foetida biodiesel in diesel engines

• Decanol enhances SFB's brake thermal efficiency (BTE) and reduces fuel consumption (BSFC). • Improved miscibility and lower viscosity boost fuel atomization and combustion efficiency. • Decanol blends significantly reduce CO, HC, and smoke emissions, enhancing sustainability. • Minimal increase in NOx emissions due to decanol's oxygen content, controllable with strategies. • Combustion analysis shows faster, more intense energy release with decanol's higher oxygen content. This study examines the performance, combustion characteristics, and emission properties of Sterculia foetida biodiesel (SFB) enhanced with decanol for diesel engine applications. SFB was produced using a two-stage catalytic transesterification process, achieving a 95.2 % conversion rate under optimized conditions. Decanol was added as a co-solvent at 10 % (SFB90D10) and 20 % (SFB80D20) concentrations to improve key biodiesel attributes, including energy content and miscibility. Engine performance tests on a single-cylinder diesel engine showed encouraging results, with SFB80D20 exhibiting a 4 % improvement in brake thermal efficiency (BTE) and SFB90D10 showing a 2.5 % increase compared to pure SFB (SFB100). The addition of decanol also enhanced fuel efficiency, with a 3.5 % reduction in brake-specific fuel consumption (BSFC) for SFB80D20 and a 1.8 % decrease for SFB90D10. Emission analysis demonstrated that decanol blends significantly reduced harmful pollutants. SFB80D20 achieved reductions of 5.8 % in carbon monoxide (CO), 6.7 % in hydrocarbon (HC) emissions, and 5.1 % in smoke opacity, highlighting the environmental benefits of this blend. Importantly, the decanol blends had minimal impact on nitrogen oxide (NOx) emissions, which remains a critical concern in diesel combustion. This study showcases the potential of decanol-enhanced SFB biodiesel to improve both performance and sustainability. Decanol acts as an effective co-solvent, enhancing energy output, improving emissions control, and maintaining low NOx emissions. These findings suggest a promising pathway for cleaner, more efficient diesel engine operation and support the broader use of biodiesel as a sustainable fuel alternative.