Investigation on combustion, performance and emission characteristics of a diesel engine fueled with diesel/alcohol/n-butanol blended fuels

In this paper, the effects of diesel/methanol, diesel/ethanol, diesel/n-butanol, diesel/methanol/n-butanol, and diesel/ethanol/n-butanol blended fuels with different alcohol substitution ratios (ASR) on the combustion, performance, and emission characteristics of a diesel engine were studied and compared. Firstly, a three-dimensional computational fluid dynamics (CFD) model was established and verified by the experiment results at 2000 rpm and 25%, 50%, 75%, and 100% loads. In addition, an improved chemical kinetic mechanism, including 81 species and 358 reactions, was used to simulate the combustion process. The combustion, performance, and emission characteristics were investigated. The results showed that compared with pure diesel, the cylinder pressure, cylinder temperature, and heat release rate (HRR) were significantly increased with the increase of ASR, the ignition delay was increased and the combustion duration was decreased. Among them, 80% diesel + 10% methanol + 10% n-butanol (D80M10B10) blended fuel was the most beneficial to improving cylinder pressure, prolonging ignition delay, and shortening combustion duration. Compared with diesel, the peak cylinder pressure, peak cylinder temperature, and peak HRR of D80M10B10 were increased by 2.86%, 2.68%, and 215.26% respectively. In addition, the addition of alcohol fuels decreased soot, HC, and CO emissions. However, NOx emission increased. Comprehensive diesel combustion, performance, and emission characteristics, the best blending ratio was D80M10B10 blended fuel.