Thermal and emission analysis of waste plastic and microalgae biodiesel as a potential power source for diesel engines: A sustainable approach

The future of diesel engines is greatly influenced by ongoing research on alternative fuels. Renewable fuels have been researched and adopted by several nations to encourage the production and use of biodiesel. This study examines the energy conversion of waste plastic biodiesel and Spirulina microalgae biodiesel at a 20% blending ratio to analyze the behavior of a one-cylinder, 4-stroke diesel engine running at 1500 rpm with a compression ratio of 17.5. The authors evaluated, analyzed, and compared the engine’s combustion, performance, and emission at an incremental engine load of 25% from 25 to 100%. The findings demonstrated that the biodiesel fuel samples generated somewhat poorer efficiency but reduced emissions from the engine. At 100% load, the percentage differences between the diesel and blended fuel samples ranged from 2.4 to 7.3% for BTE, 2.9 to 16.5% for BSFC, and 1.0 to 4.62% for BSEC; however, the PM, SO2, and CO2 emissions were reduced by 1.6–28.8% except for NOx emissions, which are increased by up to 9.4%. Pure diesel exhibits the best performance characteristics; however, pure biodiesel exhibits the best emission characteristics. The 20% blended fuels showed promising results, as they exhibited comparable or slightly improved BTE values compared to their respective pure biodiesel fuels. The findings indicate that Spirulina microalgae biodiesel and waste plastic biodiesel have the potential to be utilized as substitute fuels for diesel engines; however, for the greatest performance and lowest emissions, their blending ratios and engine operating conditions must be optimized. Graphical abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.