Fast shutter line-imaging system for dual-dispersion Raman spectroscopy in ethanol and OME flames

Abstract

Chemical energy carriers synthesized from renewable energy sources such as ethanol or oxymethylene ethers (OME) will become increasingly important for CO2-neutral thermochemical energy conversion processes. Therefore, it is important to make these processes efficient and clean. This needs more predictive numerical simulation tools and an improved understanding of the combustion process. For this purpose, spatially resolved measurements of local thermochemical states in reaction zones are required, for which combined Raman- and Rayleigh spectroscopy is suitable. Since a large number of intermediate hydrocarbons occur in the reaction zones of ethanol and OME flames, Raman spectroscopy must be evolved for quantitative measurement of these species over a wide temperature range. Against this background, this study pursues the goal of creating the instrumental and apparatus-related pre-requisites. The setup of a new dual-dispersion spectrometer and its main specifications are presented. The usability of the spectrometer is demonstrated on the example of premixed and partially-premixed ethanol/air and OME-3/air flames. For this purpose, a new counterflow burner is presented, which enables laminar, single-phase combustion processes of pre-vaporized fuels.