Performance, Emission Characteristics, and Multi-Response Optimization of BaTiO3-Enhanced Cottonseed Biodiesel in a Diesel Engine

In this study, the effects of adding barium titanate (BaTiO3) nanoparticles to a cottonseed biodiesel and diesel blend on engine performance and exhaust emissions were experimentally investigated and evaluated using multiple response optimization. Fifty, 100, and 150 mg/L BaTiO3 were added to the D70CS30 (30% cottonseed biodiesel + 70% diesel) blend, which consisted of 70% diesel and 30% biodiesel by volume. Experiments were conducted on a single-cylinder, direct-injection diesel engine at a constant speed of 3000 rpm and six load levels ranging from 0.5 to 3.0 kW. Brake specific fuel consumption, brake thermal efficiency, CO, HC, CO2, and NOx results were modeled using the response surface method. While engine load showed a dominant effect on all responses, the nanoparticle effects exhibited concentration-dependent nonlinear variations. Compared to the additive-free mixture, 100 mg/L BaTiO3 reduced average fuel consumption by 6.86%, CO emissions by 21.24%, and HC emissions by 32.89%, and increased thermal efficiency by 6.17%. However, NOx emissions increased by 12.16%. Optimization scenarios focusing on performance, emissions, and equal importance yielded different operating points. In the equal-importance scenario, optimum conditions were determined as 146.02 mg/L and 1.58 kW, with a combined desirability value of 0.701. The findings indicate that performance gains should be evaluated together with emission trade-offs. These findings highlight the trade-offs between engine performance improvements and emission characteristics and demonstrate the importance of considering multiple responses when evaluating nanoparticle-enhanced biodiesel blends.