Experimental study on combustion and emission characteristics of a diesel engine fueled with 2,5-dimethylfuran–diesel, n-butanol–diesel and gasoline–diesel blends

• DMF and gasoline have similar fuel properties, but the combustion characteristics of D30 and G30 are greatly different.
• DMF and n-butanol additions have small effects on NOx, THC and CO emissions and BSFC, but reduce soot greatly.
• Fuel oxygen is more efficient than air oxygen while ignition delay has greater effects than fuel oxygen to reduce soot.
• As diesel additive, DMF is superior to n-butanol and gasoline for reducing soot emissions.
• Using DMF–diesel blends combined with medium EGR may be a better way to meet future emission standards.

In the paper, combustion and emissions of a multi-cylinder CI (compression-ignition) engine fueled with DMF–diesel, n-butanol–diesel and gasoline–diesel blends were experimentally investigated, and fuel characteristics of DMF, n-butanol and gasoline were compared. Diesel was used as the base fuel. And 30% of DMF, n-butanol and gasoline were blended with the base fuel by volume respectively, referred to as D30, B30 and G30. Results show that compared to B30 and G30, D30 has longer ignition delay because of lower cetane number, which leads to faster burning rate and higher pressure rise rate. With increasing EGR (exhaust gas recirculation) rate, D30 gets the lowest soot emissions, and extended ignition delay and fuel oxygen are two key factors reducing soot emissions, and ignition delay has greater effects than fuel oxygen on soot reduction. In addition, D30 and B30 improve the trade-off of NOx-soot remarkably and extend low-emission region without deteriorating fuel efficiency by utilizing medium EGR rates (<40%). As diesel additive, DMF is superior to n-butanol and gasoline for reducing soot emissions due to its prolonged ignition delay and atomic oxygen. Using DMF–diesel blends combined with medium EGR may be a better choice for diesel engine to meet future emissions regulations with high fuel efficiency.