NUMERICAL SIMULATION ON THE INFLUENCE OF METAL RADIATION SHIELD ON THE THERMAL INSULATION PERFORMANCE OF THE SEMI-TRANSPARENT MATERIALS

Foams, flexible felt and thermal barrier coatings are widely used in the thermal insulation fields. This type of material has lower density and thermal conductivity, as well as higher specific surface area and porosity, and is generally referred to as the semi-transparent materials. The radiation heat transfer inside the semi-transparent materials belongs to medium radiation, so the radiation thermal con-ductivity is larger at high temperature. However, the metal radiation shields (MRS) play an important role in weakening radiation heat transfer. In order to study the effect of MRS on the thermal insulation performance of the semi-transparent ma-terials, the numerical simulation of coupling heat transfer of heat conduction and heat radiation is carried out. The effective thermal conductivity of the semi-trans-parent materials with different extinction coefficient is calculated when the differ-ent layers of MRS are evenly inserted into the semi-transparent materials at the specific temperature, so that the influence of MRS on the thermal insulation per-formance of the semi-transparent materials can be obtained. The simulation results show that whether it is an optical thin medium or an optical thick medium, when seven layers of MRS are inserted into the semi-transparent materials, the thermal insulation performance is greatly improved. After that, the effective thermal con-ductivity changes little with the increase of the layer of MRS.