Gaseous emissions (regulated and unregulated) and particulate characteristics of a medium-duty CRDI transportation diesel engine fueled with diesel-alcohol blends

In this study, different diesel-alcohol (methanol, ethanol, and butanol) blends termed as 'diesohols' were used to investigate the performance and emission characteristics of a modern common rail direct injection (CRDI) transportation diesel engine. A comparative characterization of regulated emissions, unregulated emissions, and particulate matter (PM) to explore suitability of methanol, ethanol, and butanol blending with mineral diesel was the main objective of this study. In this study, engine experiments were performed at different engine loads (3, 6, 9 and 12 bar BMEP) and speeds (1500, 2500 and 3500 rpm). Results showed that the use of diesohols improved the engine performance, leading to relatively higher brake thermal efficiency (BTE) compared to baseline mineral diesel. Addition of alcohols in mineral diesel reduced both, the PM, and the oxides of nitrogen (NOx) emissions and this reduction was dominant at higher engine loads. Trace concentrations of various unregulated emission species such as isocyanic acid (HNCO), formaldehyde, etc. increased slightly with addition of alcohols in baseline mineral diesel. However, diesohol-fueled engine emitted relatively lower concentrations of sulfur dioxide (SO2), nitrogen oxide (NO), etc. compared to baseline mineral diesel. Amongst different primary alcohols, methanol showed most significant reduction in NOx and PM emissions and most significant increase in BTE compared to other alcohols. Overall, addition of alcohol, especially methanol and ethanol in mineral diesel showed significant potential for engine performance improvement and exhaust emission reduction in a medium duty CRDI transportation diesel engine.