A computational fluid dynamics study of propane/air microflame stability in a heat recirculation reactor

The stability of a single-pass heat recirculation microburner is studied using computational fluid dynamics and compared to a single channel (no recirculation) with respect to critical heat loss coefficient, power loss, and critical inlet velocity. The effects of reactor length and outer wall thickness are also explored. It is shown that heat recirculation profoundly affects blowout due to preheating of the cold incoming gases but has a minimal effect on extinction. The inner wall of the heat recirculation microburner is found to more strongly impact stability than the outer wall, with most stable burners having both walls (inner and outer) insulated. Under certain conditions, the heat recirculation reactor can operate with moderate outer wall temperatures and room-temperature inlet and outlet streams while exhibiting high thermal efficiency.