Investigation on combustion and emission characteristics of a common rail diesel engine fueled with diesel/n-pentanol/methanol blends

Diesel, n-pentanol, and methanol can form stable, transparent and homogenous fuels. Combustion and emission characteristics of diesel, n-pentanol and methanol blends are investigated on a common rail diesel engine. Test fuels are noted as D100 (diesel), D80P20 (20% n-pentanol and 80% diesel, by vol.), D70P20M10 (20% n-pentanol, 10% methanol and 70% diesel, by vol.) and D70P15M15. At low and partial loads, blend fuels exhibit obviously longer ignition delays, higher peak heat release rates, shorter combustion durations and higher peak combustion temperatures than diesel. At medium and high loads, high oxygen contents result that blend fuels have higher intensities of diffusion combustion than diesel and thereby higher peak combustion temperatures. With the increase of methanol blending ratio, the ignition delay prolongs, the combustion duration shortens, and the peak combustion temperature increases. Also, the soot emissions decrease and NOx emissions increase with methanol. Retarding injection timing may decrease the NOx emissions, whereas increase the soot emissions for D100, D80P20 and D70P20M10. D70P15M15 has the lowest soot and ultrafine particles emissions and suitable retarding can simultaneously decrease the soot and NOx emissions compared to diesel in original injection timing, especially at medium and high loads.