Karakteristik Emisi Mesin Diesel Berbahan Bakar Biodiesel Sawit B50 Dengan Penambahan Zat Aditif

Abstract

This study aimed to evaluate the emission characteristics of a diesel engine fueled with B50 palm biodiesel blended with 2-Ethylhexyl Nitrate (2-EHN) and Butylated Hydroxytoluene (BHT) additives under different engine loads. Four fuel variations were investigated, namely B0 (diesel fuel), B50, B50 with 3% 2-EHN, and B50 with 1000 ppm BHT. Engine performance tests were conducted at a constant engine speed of 2000 rpm with electrical loads of 1500 W, 2500 W, and 3500 W, and each operating condition was tested in duplicate. Exhaust emissions, including carbon dioxide (CO₂), nitrogen oxides (NOx), and smoke opacity, were measured using an exhaust gas analyzer and a smoke meter. The results showed that B50 reduced NOx and smoke opacity compared with B0 under low and medium loads, while CO₂ emissions tended to be higher under medium and high loads, indicating more complete combustion. Among the additive-treated fuels, B50+BHT exhibited the greatest reduction in NOx emissions, whereas B50+2-EHN produced the lowest smoke opacity at high load. Two-way ANOVA revealed that fuel type and engine load significantly affected CO₂ emissions (p < 0,05), whereas only engine load significantly influenced NOx and smoke opacity (p < 0,05). In addition, a significant interaction between fuel type and engine load was observed only for CO₂ emissions. Overall, B50 without additives demonstrated the most balanced emission performance by reducing NOx and smoke opacity under most operating conditions while maintaining satisfactory combustion characteristics.