Arif Savaş, Samet Uslu, Abdullah Wali
Diesel engines play a vital role in modern society due to their widespread infrastructure and are extensively used in agriculture, transportation, and power generation because of their durability and high efficiency. However, increasingly strict emission regulations demand innovative fuel strategies to reduce environmental impacts while enhancing combustion performance. This study investigates the effects of magnetic nickel cobalt iron oxide (Ni 0.5 Co 0.5 Fe 2 O 4 ) nanoparticle addition to diesel fuel on engine performance and exhaust emissions. The novelty of this study lies in the experimental–statistical integration of Ni–Co ferrite nanoparticles in diesel fuel and the development of a multi-objective optimization model that simultaneously evaluates engine performance and emission characteristics, thereby addressing a significant gap in the existing literature. Experiments were conducted at a constant speed of 3000 rpm under six engine loads ranging from 0.5 to 3 kW, with nanoparticle concentrations of 50, 100, and 150 ppm. BSFC, BTE, and regulated emissions (CO, CO 2 , HC, and NO x ) were analyzed, and RSM was employed for multi-objective optimization. In comparison to plain diesel fuel, the results showed that modest magnetic nanoparticle dosages greatly improved combustion characteristics, attaining up to an 8.88% drop in BSFC and a 9.97% improvement in BTE. Additionally, CO and HC emissions decreased by 22.67% and 31.43%, respectively. The RSM models showed strong predictive capability (R 2 > 95% for all responses). Optimal operating conditions were identified at a 1.33 kW engine load with 103.24 ppm Ni 0.5 Co 0.5 Fe 2 O 4 addition, providing a balanced trade-off between performance improvement and emission control. These results demonstrate the possibility of diesel fuel augmented with magnetic nanoparticles as a viable strategy for cleaner and more effective diesel engine operating.