Synthesis of spirulina microalgae biodiesel, and experimental research of its effects on compression ignition engine responses with iron II-III oxide (Fe3O4) nanoparticle supplementation

Abstract

The raw material from which biodiesel is produced, the pioneer of alternative fuels in compression ignition engines, has increased importance in recent years. Third-generation biodiesels, which do not harm the food chain and environment, have become popular in recent years. In this study, fuel mixtures were obtained by mixing biodiesel produced from spirulina microalgae, the third-generation biodiesel type, with diesel and iron II-III oxide (Fe3O4) at different concentrations. Microalgae biodiesel (MAB) was mixed with diesel at two different percentages (10% and 20%), and three diverse quantities of Fe3O4 (25, 50, and 75 ppm) were added to 20MAB80D. Since the effects of the fuel mixture containing 20% MAB on the engine response are more optimistic, nanoparticles were added to the fuel containing 20% MAB. These fuel blends were evaluated under various engine loads (from 25% to 100%) at a constant engine speed (1500 rpm), and a compression ratio (15.5:1). Brake thermal efficiency (BTHE) and brake mean effective pressure (BMEP) improved with the addition of both MAB and Fe3O4. Compared to diesel (D100), the highest increases were achieved with 20MAB80D75IO fuel, with an average of 28.64% and 13.18%, respectively. With the 20MAB80D, these increases averaged 12.85% and 3.85%, respectively. On the other hand, brake-specific fuel consumption (BSFC) response increased with MAB and decreased with Fe3O4. With 20MAB80D75IO fuel, it showed an average decrease of 19.02% compared to BSFC diesel. With the 20MAB80D, there was an average increase of 11.31%. MAB and Fe3O4 contributed to reducing carbon monoxide (CO) and hydrocarbon (HC) emissions, which are products of incomplete combustion. With 20MAB80D75IO fuel, an average of 24.21% and 57.36% reductions were achieved, respectively, compared to D100. With the 20MAB80D, there was an average of 20.14% and 22.62% reductions, respectively. Conversely, NOx produced by 20MAB80D75IO was 11.63% higher than D100, while NOx produced by 20MAB80D was 3.83% higher. In conclusion, the experimental data obtained using Fe3O4 nanoparticles added to improve engine responses by improving the properties of MAB produced as third-generation biofuels revealed that MAB would be an excellent alternative fuel and Fe3O4 was a suitable additive.