Observation of OME-diesel blends spray injected by a single-hole nozzle injector under engine-relevant conditions

The fuel generated from CO2 and H2 derived from renewable energy is called “e-fuel”. Among the e-fuels, polyoxymethylene dimethyl ether (OME) is expected as a promising drop-in fuel for CI engines because it has good ignitability and low-soot combustion characteristics. However, the fuel properties such as density, heating value, and stoichiometric air-fuel ratio are different from those of diesel fuel. In this study, the spray and combustion characteristics of OME-diesel blends fuel were investigated and compared with diesel spray under engine-relevant condition at 920K-6.0MPa in a constant volume vessel. First, the fuel sprays were observed using high speed cameras under the non-reacting condition with O2 concentration of 0%. The result showed that spray-tip penetration length of OME-diesel blends was almost the same as diesel fuel, irrespective of the OME blend ratios, while the spray cone angle and spray projected area increased as the OME blend ratio increased. Moreover, the liquid phase length and width of OME spray were smaller than diesel spray. Then the reacting sprays were observed under the combustion condition with O2 concentration of 16% to understand combustion characteristics. The result showed that the ignition delay and the flame lift-off length were shortened as the OME blend ratio increased.