Extending the region of stable homogeneous micro-combustion through forced unsteady operation

Abstract

The concept of a reverse-flow (RF) operation to extend the region of self-sustained homogeneous combustion at the microscale is introduced. In the RF operation, the input and output ports are periodically switched. Thus, the energy stored in the solid structure in one cycle is released to the cold inlet stream in the next cycle, resulting in heat recirculation. Here we demonstrate that a significant increase in the stability limits can be obtained using the RF operation, over the unidirectional steady state operation, for the case of a stoichiometric propane–air mixture. The possibility of using the frequency of flow reversal as a “tuning parameter” to control the amount of heat recirculation is investigated. Finally, the effect of burner size (length, gap width, and plate thickness) on the RF operation is presented. Strong thermal interaction between the fluid and solid phases, which is possible only in microburners, is shown to be critical for the RF operation.