Study on Heat Transfer Characteristics and Performance of the Full Premixed Cauldron Stove with Porous Media

Abstract

The cauldron stoves used in restaurants and canteens usually adopt the combustion mode of blast diffusion. Low combustion efficiency leads to low thermal efficiency and high CO and NOx emissions. To address these problems, a 52 kW fully premixed stove with porous media is designed, and the heat transfer characteristics of the stove are analyzed by theoretical analysis and numerical simulation. The results show that under the rated power, the thermal efficiency of the stove reaches 68.55%, which is more than twice the thermal efficiency of the traditional blast diffusion stove. Among them, the radiant heat efficiency of the stove reaches 47.16%; thus, radiation heat transfer has become an important way of heat transfer of the porous media stove. Moreover, increasing the diameter and emissivity of porous media will increase the radiant thermal efficiency of the stove, but it will significantly reduce the flame temperature. In addition, the influence of the diameter is greater than the emissivity. The increase of the thickness of porous media can significantly improve the preheating temperature of the premixed gas, thus improving the ignition performance of the stove. Additionally, the stove has an appropriate thickness (approximately 3 mm), which not only ensures the preheating temperature but also does not easily allow for breakage and damage of porous media. Increasing the pore density or reducing the porosity of porous media can enhance the ignition performance of the stove. Moreover, the results of numerical simulation verify the theoretical results to a certain extent and shows that there is an optimal flue position as well.