Synergistic enhancement of algal biodiesel using glycerol-based oxygenates and magnetised nano-additives for CI...

The pursuit of cleaner, more sustainable fuels has intensified amid concerns about fossil fuel depletion, greenhouse gas emissions, and energy security. Algal biodiesel, a third-generation biofuel with high lipid yield and carbon-neutral potential, holds promise but suffers from lower calorific value, higher viscosity, and associated performance and emissions drawbacks. Limited studies have explored the combined use of bio-based oxygenates and magnetically conditioned nano-additives to address these limitations. This study aimed to evaluate the effects of incorporating 10% v/v glycerol-derived triacetin and 50 ppm Fe₃O₄ nanoparticles, subjected to inline magnetic treatment, on the performance and emissions of algae-based biodiesel in a single-cylinder compression ignition engine. Fuel blends were prepared and tested under varying loads using response surface methodology with analysis of variance to model brake thermal efficiency (BTE) and nitrogen oxides (NO_x) emissions. Results showed that the dual-additive blend achieved a peak BTE of 33.2% at full load, outperforming neat biodiesel by 10.7% and diesel by 1.2%, with significant reductions in CO (up to 66%), HC (up to 62.5%), and smoke opacity (over 55%). At optimised operating conditions of 57.5% load and 200 bar injection pressure, BTE reached 26.5% with NO_x emissions of 778.8 ppm, representing a viable trade-off between efficiency and emissions. Statistical models displayed high predictive accuracy with R² values of 0.9973 for BTE and 0.9168 for NO_x. These findings suggest that combining waste-derived oxygenates with magnetised nanoparticles can improve combustion quality and enhance emission control, supporting scalable pathways toward cleaner diesel alternatives. Future research should extend to multi-cylinder systems, transient operation, and long-term durability assessments.