At the Chair of Sustainable Mobile Drivetrains, a single-cylinder research-engine with a displacement of 4.8 liters and optical access to the combustion chamber was developed for the thermodynamic and optical investigation of natural gas combustion. The engine is equipped with an in-house developed endoscope with fisheye-characteristics, which consists of 9 lens elements in 7 groups and offers a 180° field of view. The complete combustion chamber becomes visible without the high constructive effort of conventional transparent engines with glass-piston [doi].
In first experiments, the engine was fired with natural gas and mixtures of natural gas with up to 40 vol% hydrogen. Gas blends with up to 10 vol% hydrogen did not affect combustion behavior significantly, so that storage of moderate amounts of hydrogen in the gas grid is unlikely to cause issues with existing systems. Higher hydrogen content, however, may lead to increased formation of nitrogen oxides, so that engine calibration has to be adapted [doi].