CFD investigation on premixed micro-combustion of hydrogen–air mixture: effects of chamber size, wall heat conductivity and fuel/air flow rate

In the present work a CFD modeling was carried out to investigate the combustion of h2/air mixture in micro channels. Conservation equations of mass, momentum, species transport and energy were discretized on small control volumes and solved using SIMPLE algorithm. Nine species with nineteen reversible reactions were considered in the premixed combustion model. Different operating and geometrical conditions including combustor size, wall conductivity and fuel/air flow rates were investigated. The results show that the wall thermal conditions have strong effects on the combustion especially when the chamber dimension goes smaller and the ratio of surface area to volume becomes larger. All three factors, such as larger heat loss through the chamber wall and smaller chamber dimension size and higher fuel/air flow rate may lead to the thermal quenching of micro-scale combustion. The simulation results also indicate that Stable combustion in the micro combustor is achievable by system optimization of the combustor geometry, thermal conditions and reacting flow dynamics.

Keywords:

micro combustion , premixed flame , CFD , flame temperature