Studies On The Heat Transfer Of Industrial Plant’s Exterior Wall Under The Heat Source Radiation In Summer

With the rapid growth of China’s economy, the scale and number of industrial buildings are increasing. However, the research on energy saving of industrial buildings is lagging behind.There are often high temperature heat sources which send out a lot of radiation heat to the surrounding space in the industrial plants.It is of great significance to the thermal design of building envelope of this kind of industrial building to study the influence of the radiation of internal heat source on the heat transfer process of the external wall of industrial thermal plant in summer.In this paper,the heat transfer theory of building envelope has been first analyzed, and find that the thermal conductivity, the emissivity of the inner wall, the emissivity of the outer wall and the solar radiation absorption coefficient are the important factors that affect the heat transfer process oftheexternalwall.A scale experimental model of industrial heat plant has been set up, the outdoor meteorological parameters, the wall temperatures and other parameters of the south wall has been tested under the two conditions of residual heat strength 300W/m3 and 0W/m3 in summer outdoor conditions in Xi’an.Theresults show that when the residual heat intensityis 300W/m3,the heat flux in the south wall is transmitted from the inside to the outside under the radiation of the inner heat source,the outer surface distribute heat to the outdoor the whole day and the inner surface absorb heatfromtheindoorthewhole day.The influence of residual heat intensity and the emissivity of heat source surface on the heat transfer process of the south wall in summer has been studied by numerical simulation.Thetemperature of the inner and outer surface of the south wall and the difference between them increase linearly with the increasing residual heat intensity.The radiation and convective heat flux in the inner and outer wall surfaces change uniformly with the increase of the residual heat intensity.The temperature of the inner and outer surface of the south wall and the difference between them increase gradually with the increasing of the emissivity of the heat source surface,but the increasing rate decreases.The radiation and convective heat flux on the inner and outer surface of the south wall increase with the increasing of the emissivity of the heat source surface,butthe rateofincreasing gradually decreases.Through the numerical simulation of the condition of heat intensity is 300W/m3, the emissivity of the heat source surface is 1,the influence of the thermal conductivity,the emissivity of the inner wall surface,the emissivity of outer wall surface and the solar radiation absorption coefficient on the heat transfer process of the south wall has been studied.Increasing the thermal conductivity of the wall can not only help to reduce the heat dissipation on the inner surface of the south wall,but also help to enhance the heat dissipation on the outer surface of the south wall.Reducing the emissivity of the inner wall surface can reduce the heat dissipation on the inner surface of the south wall, but is not conducive to enhance the heat dissipation on the outer surface of the wall.Increasing the emissivity of the outer wall can only reduce the heat dissipation on the inner surface of the south wall,and can not increase the heat dissipation on the outer surface of the south wall.Reducing the solar radiation absorption coefficient of the outer wall surface can reduce the heat dissipation on the inner surface of the south wall during the daytime, but it has little effect on the increasing of the heat dissipation on the outer surface of the south wall during the daytime.The research results lay a theoretical foundation for the energy saving and optimization design of industrial buildings.