Experimental Investigation of ZnO Nanoparticle-Blended Biodiesel on Engine Emissions

Abstract

The depletion of fossil fuels and the stringent emission norms have accelerated the search for cleaner alternative fuels in compression ignition (CI) engines. Biodiesel has emerged as a promising renewable substitute; however, its higher viscosity and oxygen content often influence combustion and emission characteristics. In this study, zinc oxide (ZnO) nanoparticles were dispersed into biodiesel–diesel blends to enhance combustion efficiency and reduce exhaust emissions. ZnO nanoparticles were added in varying concentrations (25, 50, and 75 ppm) using an ultrasonication process to ensure uniform dispersion. The experimental investigation was conducted on a single-cylinder, four-stroke, direct injection diesel engine under different load conditions. The results revealed that ZnO nanoparticle addition improved brake thermal efficiency (BTE) and significantly reduced carbon monoxide (CO), hydrocarbon (HC), and smoke emissions compared to neat biodiesel. A slight increase in NOx emissions was observed at higher nanoparticle concentrations due to improved combustion temperature. Overall, ZnO nanoparticle-blended biodiesel demonstrated superior emission characteristics and combustion performance compared to conventional biodiesel blends.