Steady-state Engine Evaluation of Nanoparticle-enhanced Renewable Fuel with Fixed-dose Additive Dispersion

Compression-ignition engines remain essential for power generation and transportation, and renewable fuels are employed to reduce regulated emissions. A fixed-dose, direct comparison of oxide-conditioned biodiesels from Calophyllum, Nerium, and Mahuva under identical operating conditions and measurement protocols has not yet been reported. In this work, steady-state BSFC, BTE, exhaust-gas temperature, CO, HC, NO, and smoke emissions of Al₂O₃-, CeO₂-, and TiO₂-conditioned biodiesels were compared with those of diesel. Biodiesels were produced by base-catalyzed transesterification, conditioned with fixed additive and nanoparticle doses, and evaluated at five brake power points using dynamometer measurements and standard exhaust analyzers. At 5.024 kW, the minimum BSFC was 0.226 kg·kW⁻¹·h⁻¹ for TiO₂-conditioned Mahuva, compared with 0.259 kg·kW⁻¹·h⁻¹ for diesel, representing a 12.7% reduction and indicating lower fuel consumption per unit brake output. At 5.024 kW, BTE ranged from 28.3 to 31.85% for oxide-conditioned biodiesels and was 34.1% for diesel. Smoke opacity for Al₂O₃-conditioned Calophyllum was 8, compared with 9 for diesel. NO levels for most treated blends ranged from 790 to 890 ppm, while one Al₂O₃ + Calophyllum trace reached approximately 980 ppm, indicating overall soot suppression alongside load- and treatment-dependent NO formation. These fixed-dose benchmarks support reproducible screening of biodiesel formulations and provide consistent inputs for combustion–emission model calibration. Future work will focus on dispersion stability during extended operation, injector deposit formation, and particle-number characterization under transient duty cycles.