Combustion and Emission Characteristics of Butanol-Diesel Blend (B15) Doped with Diethyl Ether, Diglyme and Ethyl Diglyme in a CRDI Diesel Engine

Butanol is a potential alternative fuel for diesel in compression ignition (CI) engines. Many of the physico-chemical properties of butanol such as low carbon-to-hydrogen (C/H) ratio compared to diesel, higher heating value, lower heat of vaporization and suitable density-viscosity values compared to ethanol and methanol makes it suitable as an alternative fuel. However, poor cetane number and miscibility are the limitations associated with butanol. The use of fuel additives as ignition improver could be beneficial in overcoming the issues associated with alcohols. In this work, an experimental investigation in a twin-cylinder CI engine was carried out to assess the effect of doped cetane improving additives (Diethyl ether (DEE), Diglyme (DEGME) and Ethyl diglyme (DEGEE)) for diesel-butanol blend (B15). Cylinder pressure trace, heat release rate (HRR), location of maximum in-cylinder pressure (P_max) and maximum rate of heat release (HRR_max), engine performance (brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC)) and gaseous emissions (oxides of nitrogen (NOx), carbon monoxide (CO), carbon dioxide (CO₂) and total volatile organic compounds (VOCs)) for blends of diesel and butanol (15% v/v) were measured and evaluated to determine the effect of these doped additives. B15 showed elevated cylinder pressure (~9% higher than diesel P_max) and higher HRR_max (~9.3% higher than diesel). Higher BTE and lowest BSFC was recorded for B15 doped with DEE (B15+DEE) with lowest CO₂, NOx and VOCs emissions among tested conditions.