Energy-Exergy Analysis of Diesel Engine Fueled with Microalgae Biodiesel-Diesel Blend

Renewable energy is getting more attention in recent times due to the rapid depletion of fossil fuel reserves. Production and consumption of biofuels derived from biomass has significantly increased. In the present work, Spirulina microalgae have been chosen as feedstock for biodiesel production. Diesel and biodiesel were mixed in different volumetric ratios to prepare fuel blends (SBF₀, SBF₂₀, SBF₄₀, SBF₆₀, SBF₈₀, and SBF₁₀₀). Energy and exergy analysis has been performed on a four-stroke, single-cylinder diesel engine. Experimentation was done under varying loads at 1500 RPM. The effect of multiple loads and blends was investigated for brake power (BP), cooling water losses (Q_w), exhaust gas losses (Q_exh), and unaccounted losses (Q_un). Pure diesel SBF₁₀₀ has the highest and lowest exergy efficiencies, respectively equaling roughly 31.65% and 29.75%. It has been observed that BP and Q_w increase with the increase in load whereas Qexh and Qun show a decreasing trend. It was also observed that with an increase in blending, Qw increases while Qexh decreases. In the exergy analysis, it was observed that the exergy destruction rate has a maximum fraction of input exergy values of 46.01% and 46.29% for Diesel and SBF₂₀ respectively. The system engine sustainability index was in the range of 1.27 to 1.46, which is directly related to exergy efficiencies.