Abstract
Biodiesel has emerged as a promising alternative to conventional diesel fuel, offering potential reductions in greenhouse gas (CO2) emissions. However, its use in diesel engines results in higher levels of nitrogen oxides (NOx). This study investigates emulsification techniques for reducing NOx emissions from biodiesel combustion. Two techniques, glycerin and water emulsification, are examined. Approximately 10 vol. % of crude glycerin is produced during biodiesel manufacturing as a waste or by‐product. The study attempts on‐site purification of crude glycerin, which is then used as a phase for glycerin‐biodiesel emulsions. These emulsions are compared to water emulsions in terms of emulsion stability, mean particle droplet size, microscopic fuel structure, and fuel properties. In addition, engine performance and emissions are evaluated using a small direct injection (DI) diesel engine, with both water and glycerin emulsion fuels. Results show that both emulsion fuels significantly reduce smoke emissions and further mitigate NOx emissions from biodiesel combustion. With 10% glycerin and water emulsions, smoke emissions were reduced by over 50% compared to pure biodiesel, and NOx emissions decreased by more than 15%. Emulsification techniques in the biodiesel industry could offer a viable solution for reducing both smoke and NOx emissions. Employing glycerin emulsification not only decreases NOx emissions but also transforms crude glycerin into a value‐added resource. Otherwise, disposal of crude glycerin could pose significant challenges for small and remote biodiesel producers due to cost constraints.