Energizing tomorrow: unleashing spirulina's potential in engine performance optimization and emission reduction.

Dwindling of fossil fuels and the global climate change has prompted civilization to look into alternate energy sources. This has led to explore inexhaustible and sustainable resources in the domain of renewable energy. Among all sources renewable energy, biofuel produced from biomass has great prospect for energy security as well as environmental safety over fossil fuels. The present work tries to explore the performance attributes and emission characteristics of a CI engine utilizing spirulina microalgae biodiesel blend comprising of 20% algae biodiesel blended with 80% diesel. This blend is tested in a diesel engine at varying engine load conditions of 20%, 40%, 60%, 80%, and 100% at variable injection timing of 20°, 23°, 25°, and 28° bTDC, respectively at compression ratio of 18. Based on experimental results, the peak brake thermal efficiency for injection timing of 20°, 23°, 25°, and 28° bTDC at 100% engine load were observed to be 26.79%, 23.77%, 24.77%, and 25.09%, respectively for the biodiesel blend in comparison to 27.76% of diesel mode whereas the emissions levels were found to minimum at 20° bTDC. On the part of emission, the average drop in CO emissions for injection timing of 20°, 23°, 25°, and 28° bTDC were found to be 53.46%, 43.71%, 44.34%, and 50.31%, respectively for biodiesel blend as compared to diesel mode. For the same setting, in comparison diesel mode, the average fall in HC emissions were found to be 42.32%, 34.13%, 30.37%, and 37.54%, respectively, and the rise of NOx emissions were found to be 8.06%, 5.55%, 3.51%, and 3.04%, respectively. Response surface methodology was applied for optimization of operating parameters of the algae biodiesel blend run diesel engine. The desirability based study revealed that at 85.19% engine load and injection timing of 20° bTDC were optimal operation settings which resulted in engine performance of 25.44% brake thermal efficiency. The emission level at this setting was observed to be reduced to 27.68 ppm CO, 1.60% CO2, 24.65 ppm HC, and 182.15 ppm NOx.