Simultaneous high-speed spectroscopy and 2-color pyrometry analysis in an optical compression ignition engine fueled with OME_X -diesel blends

摘要

E-fuels are a very attractive way for improving the well-to-wheel emissions of CO 2 in internal combustionengines. In the particular case of compression ignition engines, the Oxymethylene dimethyl ether (OME_X ),an e-fuel with nearly soot-free combustion under mixing-controlled conditions, is a good candidate forthe replacement of fossil fuels. However, the Lower Heating Value of OME_X is nearly half of the dieselfuel, which means that much longer injection durations are required in the real engine. In addition, thevery low viscosity and lubricity of OME_X can damage the injection system if used pure, but it can bean interesting fuel when blended with conventional diesel. Thus, the main objective of this paper is toevaluate the potential of OME_X -diesel blends to bypass these OME_X limitations whilst keeping low sootformation trends. For this purpose, a single cylinder optical diesel engine at part load was employed.The soot production for the different fuel blends was analyzed by applying three different high-speedimaging techniques: natural luminosity, flame spectroscopy and 2-color pyrometry. Natural luminosityanalysis showed that the flame light intensity scales with diesel fraction up to 30% of diesel in the blend.The spectroscopy analysis has revealed that soot formation of OME_X fuel is almost null. When blendedwith diesel at 50%, although soot formation is still lower than for pure diesel, higher soot levels areobtained in the last stages of the cycle as a consequence of the longer injections required.