Comparative assessment of the effects of higher alcohols/diesel blends on performance and emissions of a direct-injection diesel engine

Abstract

This study evaluates the effects of incorporating 20% v/v concentrations of higher alcohols (1-butanol, 1-pentanol, and 1- octanol) into diesel fuel on the performance and emission characteristics of a direct-injection diesel engine. Through experimentation, we discovered that the 1-butanol blend (D80B20) notably enhanced the brake thermal efficiency (BTE) across various brake mean effective pressure (BMEP) values, signifying a marked improvement in combustion efficiency over conventional diesel fuel. Additionally, D80B20 demonstrated a significant reduction in carbon monoxide and nitrogen oxide emissions, along with a considerable decrease in smoke opacity, suggesting a cleaner combustion process attributable to the high oxygen content and favorable volatility of 1- butanol. Although the 1-pentanol blend (D80P20) moderately improved BTE and reduced smoke opacity at specific BMEP levels, its benefits were less pronounced than that of D80B20. The 1-octanol blend (D80O20), however, faces challenges at higher loads, with exhaust gas temperatures often surpassing those of pure diesel, indicating less effective combustion owing to the longer carbon chain of 1-octanol. Our findings highlight the potential of alcohol–diesel blends, especially D80B20, in significantly enhancing engine performance and reducing environmental impact through lower emissions. Thus, selecting appropriate alcohol types and optimizing blend ratios will provide environmental and operational benefits for diesel engines.