CeO2-Enhanced Diesel for Maritime Applications: Experimental Performance and Emissions Assessment with ANP-Based Risk Prioritization

This study investigates the effects of cerium oxide (CeO2) nanoparticle-enriched diesel fuel on engine performance and exhaust emissions and prioritizes the risks that may be encountered in marine applications. Pure diesel and mixtures containing 25, 50, and 100 ppm CeO2 were experimentally evaluated in a single-cylinder, direct-injection diesel engine at a constant speed of 1800 rpm and different loads. While the effect of the additive on the basic physicochemical properties of the fuel remained limited, the most significant improvements in fuel consumption and incomplete combustion indicators were observed in the 50 ppm mixture. In this mixture, specific fuel consumption decreased by 6.68%; carbon monoxide, hydrocarbons, and smoke opacity decreased by 9.19%, 9.18%, and 8.50%, respectively. However, increases were observed in carbon dioxide concentration, the measured NO-channel indicator, and exhaust temperature. Thirty-eight risk criteria, encompassing technical, environmental, health and safety, and economic and operational aspects related to shipboard use, were ranked using the Analytical Network Process based on assessments by ten experts. Economic and operational risks received the highest overall priority at 34.37%, with maintenance costs, limited operational uptime, and additional equipment investment being prominent. The findings indicate that long-term validation, exposure assessment, and life cycle analysis are necessary to transfer laboratory-scale gains to ships.