Numerical investigations on an improved dual-channel porous combustor fueled with lean methane for enhancing thermal performance

In this work, an improved dual-channel porous combustor is designed. Extensive numerical investigations are conducted to compare the thermal performance between the single-channel and the improved dual-channel combustor under various inlet velocity, methane concentration and the pores density of foam ceramics. Moreover, the effective thermal conductivity model of the foam ceramic based on the Kelvin decahedron was introduced. The external and internal heat circulation and the heat circulation efficiency of the burner are calculated and analyzed quantitatively. Results show that, at low methane concentrations conditions, the pores density of foam ceramics have no significant effect on the blow-off limits for both single-channel and dual channel porous burners. However, under the higher methane concentrations conditions, the blow-off limit would be increase with the pores density of foam ceramics. Compared with the single-channel burner with 20 PPI foam ceramic, the mean nonuniformity of the foam ceramics temperature for the improved dual-channel combustor would be reduced from 2.015% to 26.562% when the inlet velocity increases from 0.1 m/s to 0.16 m/s. However, for the 10PPI to 40PPI burners, the mean nonuniformity of the solid phase temperature of the improved dual-channel combustor would be reduced by 9.78% to 4.36%. Moreover, the preheat zone inside the porous medium would be greatly minimized by the addition of external heat recirculation to the porous media burners.