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

Article Open access Published: 11 October 2026 Scientific Reports ( 2026 ) Cite this article We’re sharing this article early to provide faster access to peer-reviewed, accepted research. It is citable and carries a permanent DOI. This version is subject to further edits and will be replaced automatically by the final Version of Record. All legal disclaimers apply. Abstract 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. Abbreviations BR: Blend ratio BP: Brake power BTE: Brake thermal efficiency BSFC: Brake specific fuel consumption CRDI: Common rail direct injection CO: Carbon monoxide CO 2 : Carbon dioxide CR: Compression ratio D90RB10: Diesel 90% & Rice bran oil 10% D85RB15: Diesel 85% & Rice bran oil 15% D80RB20: Diesel 80% & Rice bran oil 20% D75RB25: Diesel 75% & Rice bran oil 25% D90LP10: Diesel 90% & Lemon peel oil 10% D85LP15: Diesel 85% & Lemon peel oil 15% D80LP20: Diesel 80% & Lemon peel oil 20% D75LP25: Diesel 75% & Lemon peel oil 25% D90RB5LP5: Diesel 90% + Rice bran oil 5% + Lemon peel oil 5% D85RB7.5LP7.5: Diesel 85% + Rice bran oil 7.5% + Lemon peel oil 7.5% D80RB10LP10: Diesel 80% + Rice bran oil 10% + Lemon peel oil 10% D75RB12.5LP12.5: Diesel 75% + Rice bran oil 12.5% + Lemon peel oil 12.5% ECU: Engine control unit EGT: Exhaust gas temperature EL: Engine load FAME: Fatty acid methyl ester FIP: Fuel injection pressure GRC: Grey relational coefficient GRG: Grey relational grade HC: Hydrocarbon LPO: Lemon peel oil MRPI: Multi-response performance index NOx: Nitrogen oxides RB: Rice bran VCR: Variable compression ratio Funding The authors received no funding for this work. Author information Authors and Affiliations Department of Mechanical Engineering, PES’s Modern College of Engineering, Pune, Maharashtra, 411005, India Vaibhav Rangari, Harshad Deshpande & Sameer Bhosale Department of Mechanical Engineering, Institute of Technology, Debre Markos University, P.O. Box 269, Debre Markos, Ethiopia Alemu Workie Kebede Department of Mechanical Engineering; G H Raisoni College of Engineering & Management, Pune, Maharashtra, 412207, India Himadri Majumder Authors Vaibhav Rangari Harshad Deshpande Sameer Bhosale Alemu Workie Kebede Himadri Majumder Corresponding authors Correspondence to Alemu Workie Kebede or Himadri Majumder . Ethics declarations Competing interests The authors declare no competing interests. Additional information Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 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To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ . Reprints and permissions About this article Cite this article Rangari, V., Deshpande, H., Bhosale, S. et al. Performance and emission analysis of a diesel engine fueled with rice-bran and lemon-peel oil biodiesel blends. Sci Rep (2026). https://doi.org/10.1038/s41598-026-75033-x Download citation Received : 27 March 2026 Accepted : 05 October 2026 Published : 11 October 2026 DOI : https://doi.org/10.1038/s41598-026-75033-x Keywords