On flame propagation in narrow channels with enhanced wall thermal conduction

The influence of orthotropic wall materials, which have enhanced thermal conductivity in the axial direction, on the flame speed is explored via an analytical model in a parallel plate microcombustor. The model accounts for 2D conjugate heat transfer (both in wall and gas) and fuel species transport in the micro-channel. The effects of heat loss, orthotropic wall thermal conductivities, and wall thickness on the flame speed are explored. The results indicate that as the axial thermal conductivity of the wall is increased, the allowable heat losses to the ambient by the burner also increased. Thicker walls showed increased benefit to the thermal conductivity tailoring than thinner wall designs; both in increased flame speeds as well as the ability to tolerate higher heat losses without extinction. Total heat recirculation is shown to be the primary parameter to control the flame speed. •Analytical model of flame propagation in a microchannel with orthotropic walls.•High axial thermal conductivity allows the burner to withstand greater heat losses.•Orthotropic walls can expand the operating envelope of microcombustors.•Can improve solid state (thermoelectric) power conversion by avoiding “hot spots”.