The "Flex-OeCoS" optical engine test bed for studying combustion processes using renewable fuels

Abstract

The need to address climate change requires the phasing out of fossil fuels. For the use of IC engines in sectors that are difficult to decarbonize through electrification, chemical energy carriers in the form of renewable fuels offer the potential for cost-effective GHG reduction. However, their properties in terms of ignition and combustion characteristics must be considered. The optically accessible "Flex-OeCoS" test facility allows detailed investigation of different combustion processes with novel fuels over a wide range of IC engine relevant operating parameters, i.e. up to 26 bar indicated mean effective pressure. Its sophisticated operating concept allows key parameters such as compression pressure/temperature and flow conditions to be set individually with a high degree of accuracy and reproducibility. The adaptable setup enables operation in different configurations with respect to premixed or diffusive combustion processes and different ignition systems – such as spark plug, pilot fuel spray, and turbulent jet from an active/passive pre-chamber. It has been specifically designed for the application of optical measurement techniques to determine ignition and flame propagation, in addition to the precise acquisition of thermodynamic data and characterization of exhaust gas composition. The aim of this paper is to provide a comprehensive overview of the possibilities for the fundamental investigation of individual ignition concepts, combustion behaviour, and emission formation for different combustion processes with ammonia, methanol and hydrogen using the "Flex-OeCoS" test facility.