Subprojekt MM1: Chemical conversion in an internal combustion engine running in unusual operating points

This project aims to experimentally validate and optimize the cogeneration of useful chemicals, power, and heat. The engine is run on very fuel-rich mixtures, which is highly unusual from a traditional perspective of power-optimized design and operation. Data from these experiments are compared to the modeling results from the adjoining projects GM2 and GM3. The experiments in the research collaboration FOR 1993 – plug-flow reactor, shock tube, rapid compression machine, and internal combustion engine – constitute a contiguous span with the engine experiments at its applied end.

Three experimental platforms are used: An octane-number test-engine, a modified Diesel engine operated on a single cylinder, and an optically accessible research engine. Operation is mostly with premixed charge to keep in-cylinder conditions as close to a homogenous reactor as possible, simplifying comparisons with simulations. Gas processing is varied by covering a wide parameter range in compression ratio, intake temperature and pressure, and charge composition. The primary goal is production of syngas and potentially larger hydrocarbons. Initially, the feedstock is methane, but we also examine adding dimethyl ether, ethanol, and n-heptane, premixed or by pulsed direct injection into the cylinder.

In the engine experiments, sensors capture data to calculate the heat and mass flows relevant to the balances of energy and exergy. Fast measurements of in-cylinder pressure yield the crank-angle resolved apparent heat release and are used to determine the operational knock limit. Approximate characterization of the product gas stream is performed in real-time by standard off-the-shelf gas analyzers, mainly based on infrared-absorption techniques. Together with project GV1 we also perform detailed offline speciation of product-gas samples by gas chromatography and mass spectrometry. Finally we examine the limits of considering the cylinder a homogenous reactor and image the spatio-temporal onset of reactions by laser-based imaging in the optically accessible engine.