Reducing NOx emission from palm biodiesel/diesel blends in CI engine: A comparative study of cetane improvement techniques through hydrogenation and fuel additives

Abstract

In this study, the trans-esterification process prepared palm oil biodiesel and 20% biodiesel blended with diesel (PB20) by volume as test fuel. Unsaturated fatty acids are majorly influenced by biodiesel cetane number. This work examines two-fuel reformulation methods of fuel hydrogenation and addition of fuel additive di-tert-butyl peroxide (DTBP) to enhance the engine characteristics of a PB20 blend while maintaining emission control. A reactor (autoclave) was utilized for hydrogenating the palm biodiesel and examining the change in fuel composition using gas chromatography. DTBP is selected as the cetane enhancer and combined with PB20 at a 2000 ppm concentration. Tamson FBT equipment was utilized to evaluate the test fuel's filterability. The filterability, engine characteristics, and emissions were investigated for diesel (D0), PB20, HPB20, and PB20 + DTBP fuel blends in the compression ignition test engine. The FBT results reveal that PB20 and HPB20 have better filtration quality, which aligns with the standard requirements (ASTM D2068-14). An improved NOx (10.2%) and brake thermal efficiency (6.7%) are seen at engine full loads when using modified B20 fuels. The hydrocarbon, carbon monoxide, and smoke emissions decreased by 8.3%, 6%, and 10.14% compared to diesel fuel. Hence, partial hydrogenation has been a better approach to improving biodiesel trade-off features than DTBP addition.