Abstract
The production of carbon-neutral fuels through clean energy has been defined as a target by the European Union and by several international institutions. If the concepts are available, hydrogen, in particular, is considered to be one of the most target-oriented, ecologically and economically realizable approaches. In terms of safety, long-time storage and long-distance transport of hydrogen are still under development. However, pipeline systems similar to those for natural gas are being considered. Gas quality criteria will have to be developed for this case. The effects of trace components in the hydrogen on chemical and thermal aspects are not yet sufficiently understood and need to be characterized more precisely. For these reasons, this work presents a detailed analysis for a more complete understanding of the phenomena involved. More specifically, the flame structure, temperature profile and overall reactivity were first determined for gas mixtures analyzed under four varying dilutions of carbon dioxide, carbon oxide, nitrogen and methane in hydrogen. The characterization of the total reactivity and the laminar burning velocity offers an appealing solution to quantify the effects of dilution. The most distinctive effects of the operating conditions on the ignition phenomena have been worked out numerically for the lower and upper boundaries and have been discussed. The results collected in this work provide a robust feature for a detailed evaluation of normal operation as well as the accidental release of the hydrogen-rich fuels.
