Effects of fuel properties on combustion and emissions under both conventional and low temperature combustion mode fueling 2,5-dimethylfuran/diesel blends

摘要

The effect of DMF (2,5-dimethylfuran) on combustion and emissions were investigated on a diesel engine. Four different fuels, mixture of cetane and iso-cetane, n-heptane, DMF and mixture of DMF and EHN (2-ethylhexyl nitrate), were added into diesel fuel with 20% blending ratio by volume, denoted as Reference20, Heptane20, DMF20, DMF20 + EHN, respectively. Different rates of EGR (exhaust gas recirculation) from 0% to 62% were used. Results demonstrate that there is little difference in combustion and emissions among Reference20, Heptane20 and diesel. The lower cetane number of DMF20 is the uppermost factor to control combustion process. The lower cetane number of DMF20 results in more premixed combustion, which is the main factor for soot reduction. The secondary reason is the effect of oxygen in DMF. Other physical and chemical properties of DMF20 have quite small effect on soot reduction in 20% blending ratio. The higher NO_X emissions of DMF20 are primarily due to the effect of fuel oxygen. The DMF addition has little effect on THC (total hydrocarbon) and CO (carbon monoxide) emissions. The changes in combustion and emissions of DMF20 are more sensitive to EHN at lower addition. Further, the EHN addition has larger effects on combustion and emissions at higher EGR rates.