High proportions of recirculated exhaust gases are often introduced in combustion processes to reduce emissions of harmful pollutants. They consist of carbon dioxide, water, nitrogen and individual components in traces, which also include nitric oxide (NO). Fundamental research has revealed that NO has a potential effect on combustion kinetics and thus on the temporal and spatial distribution of heat release, which potentially affects the combustion process as well as the further formation of pollutant emissions. For the first applied confirmation of these hypotheses, this thesis analyzes the process of natural gas combustion in an internal combustion engine and forced ignition at different concentrations of NO doped into the intake air. Based on the pressure trace in the cylinder, heat release, temperature and pollutant emissions, the influence of already extremely low doped NO concentrations can be detected in individual operating intervals. The effect of NO on combustion is strongly dependent on the temperature and composition of the combustible mixture. The highest sensitivity is observed at temperatures between 1600 and 1900 ° C and lean mixtures. At higher added concentrations, NO acts as an ignition promoter as it accelerates the formation of reactive OH and O radicals. NO also changes the kinetics of the formation of emissions of harmful substances, as the results confirm a significant impact on the additional formation of NO, especially in areas of low temperatures. The thesis represents the first applied confirmation of the basic hypotheses and represents initial work for further studies in realistic combustion processes.
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