Exhaust emissions with ethanol or n-butanol diesel fuel blends during transient operation: A review

• Published in: Renewable & sustainable energy reviews 2013-01, Vol.17 (1), p.170-190
• Main Authors: Giakoumis, Evangelos G., Rakopoulos, Constantine D., Dimaratos, Athanasios M., Rakopoulos, Dimitrios C.
• Format: Article
• Language: English
• Subjects: Air pollution caused by fuel industries; Alcohols: methanol, ethanol, etc; Alternative fuels. Production and utilization; Applied sciences; carbon dioxide; carbon monoxide; combustion; Diesel engine; diesel engines; diesel fuel; emissions; Energy; Energy. Thermal use of fuels; Engines and turbines; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Ethanol; Exact sciences and technology; Exhaust emissions; Fuels; hydrocarbons; Metering. Control; n-Butanol; nitrogen oxides; oxygen; particulates; pollutants; smoke; surveys; Transient operation; Transient/driving cycle
• ISSN: 1364-0321; 1879-0690
• DOI: 10.1016/j.rser.2012.09.017

The present work reviews the literature concerning the effects of alcohol/diesel blends on the exhaust emissions of diesel engines operating under transient conditions, i.e., acceleration, load increase, starting and transient/driving cycles. Two very promising alcohols are covered in this survey, namely ethanol and n-butanol. The analysis focuses on all regulated exhaust pollutants, i.e., particulate matter (PM), nitrogen oxides (NOx), carbon monoxide (CO) and unburned hydrocarbons (HC), with results for unregulated emissions, carbon dioxide and combustion noise radiation also included. The main mechanisms of exhaust emissions during transients are identified and discussed, with respect to the fundamental aspects of transient operation and the differing properties of alcohols relative to the reference diesel oil. Based on the published studies up today, summarization of emissions data and cumulative trends are presented, for the purpose of quantifying the alcohol blends benefits or penalties on the regulated emissions during various driving cycles. Particularly for the emitted PM and smoke, a statistically significant correlation with the oxygen content exists (R2=0.85 and 0.95, respectively). A similar correlation holds true for the heavy-duty, engine-dynamometer data of engine-out CO. Finally, a detailed list is provided that summarizes the main data from all studies published so far.