Optimization of Additive-Diesel Blends Using RSM on Engine Performance and Emission Characteristics

Abstract

This study investigates the effects of various additive-diesel fuel blends and operating conditions on engine performance, combustion characteristics, and exhaust emissions of a single-cylinder, four-stroke, direct-injection Yanmar TF120M diesel engine. Utilizing Response Surface Methodology (RSM) with Central Composite Design (CCD), 65 experimental runs were conducted to develop empirical models and analyze the significance of input factors such as engine speed, load, and fuel type. The selected output responses include Brake Power (BP), Brake Thermal Efficiency (BTE), Brake Specific Fuel Consumption (BSFC), Exhaust Gas Temperature (EGT), and emissions (CO, CO₂, NOx). ANOVA results confirmed that all models were statistically significant with p-values < 0.0001 and high R² values ranging from 0.8177 to 0.9949, indicating strong model reliability. The maximum improvement in BP ranged from 3.1% to 8.1% compared to pure diesel. The best BTE reached up to 35% for blends like TD and APD, showing a 6.1% enhancement over diesel. BSFC was significantly reduced by 4.3–12.8% across various blends, with APD showing the lowest consumption at 102 g/kWh. EGT was also notably affected, with a maximum reduction of 20.8% when using OAPD, indicating improved combustion efficiency. Overall, the additive-diesel blends demonstrated improved engine performance and reduced emissions, highlighting their potential as alternative fuels. The developed models are suitable for optimizing operating conditions to achieve better efficiency and environmental performance in small diesel engines.