Numerical simulation of the effect of hydrogen addition fraction on catalytic micro-combustion characteristics of methane-air

Understanding of micro-scale combustion mechanism is very essential to the development of micro-power devices, so hydrogen assisted catalytic combustion of methane on platinum was studied in this paper. The combustion of preheated mixtures of methane-hydrogen-air in a micro-combustor was modeled by a two-dimensional model including an elementary-step surface reaction mechanism. It was demonstrated that the model could predict the effects of changes of hydrogen fraction. It was shown that the mole fraction of H, OH and C(s) increase and ignition time decreases with hydrogen addition. It was also shown that the improving effect of hydrogen on the ignition temperature of the fuel and O(s) coverage is particularly evident at relatively low hydrogen fraction. The promotion of the combustion stability is due to the decrease of coefficient of variation with hydrogen addition. The methane combustion will move toward the more stabilized reaction and there is a great potential to reduce the pressure fluctuation.