Fundamental Research On Directional Radiation Heat Transfer Of Furnace Wall In Flame Furnace

Flame furnaces are important industrial heating equipment.Effective heat transfer is a critical factor which may affect the furnace’s yield,energy consumption and product quality.The most important scientific problem in the research of industrial furnace is the heat transfer enhancement.The furnace can be regarded as a ternary heat transfer system composed of furnace gas,furnace wall and materials.The furnace wall has a large surface area,and its structural form and surface radiation characteristics have an important effect on the heat transfer in the furnace.Therefore,a large number of companies and scholars have carried out research on the heat transfer of furnace walls,and proposed such technologies as blackbody technology and high-temperature coating technology.Facts show that these technologies can indeed strengthen the heat transfer in the furnace in some cases,but the specific influence law is not clear.This is mainly because the research on these technologies often stays at the experimental level without in-depth mechanism analysis.Therefore,this paper constructs the heat transfer model in the furnace,and uses the analytical method to study the heat transfer in the furnace.The mechanism of the parameters such as the blackness of the furnace wall and the structure and position of the intermediate radiators suspended on the surface of the furnace wall to enhance the heat transfer is emphasized.This article first analyzes the reason why there is no furnace wall blackness in the Timofeev formula.Based on this,the analytical formula of the heat flow on the surface of the slab in the non-gray system is deduced.The assumption that the furnace wall is a heavy radiating surface in the Timofeev formula is removed,so that the formula can analyze the influence of the radiation characteristics of the furnace wall surface on heat transfer.The research results show that only under the condition ofεg>αgw can increase the furnace wall emissivity to increase the surface heat flow of the material.In case εg≤αgw,the high-emissivity coating technology cannot enhance the heat transfer in the furnace.In order to investigate the role of the intermediate radiator,a quaternary radiant heat transfer system is constructed on the basis of the ternary model.The analytical formula of the heat flow on the surface of the material was derived,and the influence of the length and position of the intermediate radiator on the heat transfer in the furnace was analyzed.The research results show that after adding the intermediate radiator,the heat transfer on the surface of the material has been improved to a certain extent,and the value of the increase is related to the temperature of the furnace gas and the billet.Finally,in order to verify the correctness of the previous conclusions and further investigate the role of the intermediate radiator,an experimental study was carried out in this paper.Temperature in the furnace under non-steady-state and steady-state conditions are obtained by using a chamber furnace combined with an air duct.The influence of the intermediate radiator on the heat transfer in the furnace when it was at the center and sides of the furnace bottom was investigated.The results show that the analytical formula proposed in this paper is correct and can reflect the actual heat transfer in the furnace.