Effect of dimethoxymethane (DMM) additive on combustion and emission characteristics under different working conditions in CI engines

Abstract

Dimethoxymethane (DMM) is considered a potential oxygenated fuel due to its high oxygen content (42.1%) and considerable heat value. However, little research emphasizes the impact of oxygenated fuels on small-particles (DP < 25 nm), which is harmful for human beings. In this investigation, the effect of DMM-diesel mixture on combustion and emission characteristics of a four-cylinder commercial CI engine is studied under normal working speeds and loads. Especially, the influence of DMM-diesel fuels on PMs included small-particles is analyzed comprehensively. The results show that the brake thermal efficiency (BTE) of DMM13 and DMM6.4 fuels increases by 1.06% and 0.4%, respectively, compared with that of D100 at the condition of 1400 rpm and 1.0 MPa. In terms of emission, the soot emission of DMM13 is reduced by 46% with respect to that of D100 at the condition of 0.6 MPa and 1400 rpm. Meanwhile, with the addition of DMM13, the peak particle number concentration (PNC) drops significantly, but increasing the proportion of small-particles. Moreover, the lowest total particle mass concentration (TPMC) is obtained as well. Substantially, DMM-diesel blends can realize the balance between low total particle number concentration (TPNC) and small geometric mean diameter (GMD).