Combustion temperature in a three-dimensional porous stove with a high-fidelity structure

Abstract

The combustion temperature in a three-dimensional (3-D) porous stove was investigated numerically by using a novel high-fidelity structure of ceramic foam. The surface temperatures of the present stove were compared with those in corresponding experiments to verify the numerical model. Based on the discussion of gas velocity in the combustion state, the internal combustion temperature in the 3-D structure was analyzed by focusing on the solid–gas temperature profiles and the heat transfer characteristics. The results showed that large Venturi effects occurred with formation of jets on the upper surface of the ceramic foam. Numerous discrete flames were clearly formed in the 3-D pores of the ceramic foam and not only showed wrinkling induced by the staggered skeletons, but also differed significantly owing to the difference in pore structures, resulting in different temperature profiles in different axial cross-sections. The temperature for the axial cross-section with the same height was basically same in the circumferential direction, with even the same temperature difference between gas and solid. The driving force of internal heat transfer in porous media combustion (PMC) originates from the gas–solid temperature difference, resulting in the formation of an enclosing steady self-heat circulation process. The surface heat transfer coefficient (SHTC) obtained in this work agreed well with those of corresponding experiments in previous work. Their maximum region emerged near the interface between the distributor and foam ceramic, and not in the region of the maximum combustion temperature. The heat transfer coefficients gradually decreased along the axial direction in spite of undergoing combustion expansion, whereas it increased from the center to the outside edge in the radial direction. The results are conducive to numerical simulation of PMC, and helpful for combustion in domestic gas stoves.