Experimental and chemical kinetic study of the impact of n-butanol blending on the gross engine performance of a CRDI engine

Abstract

The effect of different fuel injection strategies for a CI internal combustion engine running on n-butanol/diesel blends is reported in this study. n-Butanol was blended in proportions of 5%, 10% and 20% (by vol.) and engine performance was compared with those obtained from commercially available diesel fuel. The effects of fuel injection pressure [FIP], start of injection [SOI] and split injection ratios were explored in this work. A single cylinder common rail direct injection engine running at a speed of 1050 ± 30 rpm was used for performance analysis. Initially, a baseline set of experiments were performed for all the fuel blends with the engine operating at 800 bars fuel injection pressure [FIP], 9° BTDC SOI, 3.48 BMEP and with 0% split injection. In-cylinder pressure, heat release rate, exhaust gas temperature and NOx emission were recorded for all the experiments. Additionally, for the base case, indicated gross engine performance parameters like BSFC and BTE were also determined. Subsequently, a parametric study of three different injection strategies was performed and variations in the indicated parameters and NOx emissions were thoroughly analysed. Significant reduction in NOx emission due to n-butanol blending, retarded start of injection and split injection were observed and reported as part of this work. A skeletal n-dodecane/n-butanol mechanism was used to investigate the causes for NOx emissions decrease due to the addition of n-butanol to diesel fuel. Qualitative insights gained from combustion kinetics simulations in an idealized homogeneous combustion model are discussed.