Performance and emission analysis of a diesel engine fueled with rice-bran and lemon-peel oil biodiesel blends

The growing demand for sustainable energy and for emission reductions has intensified the search for alternative fuels for compression-ignition engines. This study presents a novel experimental investigation of the combined use of eco-friendly biodiesel derived from rice bran oil and lemon peel oil, as well as their hybrid blends, in a CRDI VCR diesel engine. Unlike conventional studies that focus on single-source biodiesel, the present work uniquely explores the synergistic effects of dual biodiesel blends on engine performance and emissions. A hybrid Taguchi–Grey relational analysis (GRA) approach is implemented to evaluate the influence of key operating parameters, namely blend ratio, engine load, and fuel injection pressure, while addressing the inherent multi-response optimization challenge involving performance parameters (brake power, brake thermal efficiency, brake-specific fuel consumption, and mechanical efficiency) and emission characteristics (CO, HC, NOx, and smoke). Hybrid biodiesel blends demonstrate competitive performance and lower emissions than conventional diesel, highlighting the potential of waste-derived dual biodiesel fuels. The optimal parameter combinations indicate that blends such as D75RB25 (blend ratio of 25% RB and 75% neat diesel), engine load of 100%, and fuel injection pressure of 500, D80LP20 (blend ratio of 20% LP and 80% neat diesel); and D90RB5LP5 (blend ratio of 25% RB and 75% neat diesel ) at full load and 500 bar injection pressure can serve as viable substitutes for diesel fuel. The novelty of this work lies in the combined application of dual-source biodiesel blending and multi-objective optimization using the Taguchi-GRA method, providing a comprehensive framework for enhancing engine performance while reducing environmental impact.