12. Impact of Ethanol on Combustion, Performance, and Emission Characteristics of Diesel Engine

Diesel engines are one of the most preferred internal combustion (IC) engine for heavy-duty transport vehicles due to its higher torque characteristics and better thermal efficiency over gasoline engines. Despite of having advantages in terms of efficiency and durability, it contributes to emissions in the environment, primarily particulate matter (PM) and oxides of nitrogen (NOx). Diesel PM component is infamous for its possible carcinogenic nature. Diesel exhaust pollutants are responsible for the deterioration of air quality and harmful for human being. Formation of such air pollutants decreases significantly by blending the oxygenated fuels (such as biodiesels and alcohols) into conventional diesel. Ethanol-blended diesel fuel is a cleaner combustion choice for compression ignition (CI) engines which decreases the formation of harmful emissions in the combustion chamber. This chapter aims to review about the combustion and emission characteristics of ethanol–diesel blended fuels in CI engines. Studies show that increasing fraction of ethanol in diesel tends to reduce CO and HC emissions, while NOx emissions are reported slightly higher compare to baseline diesel. Higher ignition delay (ID) and lower combustion duration (CD) are the general characteristics for ethanol blends.