Thermal Performance of Ultra-Fine Powder Insulations at High Temperatures

The primary concern of this work deals with the prediction of ther mal performance of the ultra-fine powder insulations (UFPI) Aerosil 380 at high temperature applications. Experimental results are obtained for the spectral extinc tion coefficients of the material from infrared transmission measurements. These re sults are compared with both of the mdependent and dependent scattering and ab sorption theoretical calculations The combined conduction and radiation problem is solved by the accurate Differential-Discrete-Ordinate (DDO) method. The experi mental values of the radiative properties and effective thermal conductivity had been used to deduce expressions of solid conductivity. Based on these values, the thermal performance of UFPI can be obtained. The results show that radiative transfer ac counts for approximately 10 percent of total heat transfer in UFPI at room tempera ture range and up to 40 percent at temperatures near 1000 K.