Numerical investigation on the self-ignition and combustion characteristics of H2/air in catalytic micro channel

Abstract The self-ignition of hydrogen/air is an important process in the micro thermophotovoltaic system. The transient numerical models of gas-phase reaction and catalytic reaction in the various catalytic micro combustors were built and verified. The self-ignition process of gas-phase reaction caused by catalytic reaction in the catalytic micro channel with conventional heat dissipation was studied. The self-ignition process could be divided into four stages, fuel diffusion stage - pure catalytic reaction stage - flame front moving stage - stable combustion stage. The ignition time and temperature limit at different inlet temperatures, inlet velocities and channel heights were analyzed. The results showed that the wall quenching effect, thermal effect and flame propagation effect are dominant at low temperature, medium temperature and high temperature respectively. The catalyst length and the mixture internal energy were the main factor at low inlet velocity and high inlet velocity respectively. The steady-state time was also studied in the various operation conditions. Finally, the catalytic combustion characteristics in the stable combustion stage were analyzed. The influence of inert section length, inlet temperature and inlet velocity on the maximum temperature and fuel conversion ratio were investigated.