Analysis of Transient Thermal Measurements on Fibrous Insulations Obtained with an Unguarded Flat Tester

摘要

The unguarded screen tester is a useful apparatus for measuring both steady-state and transient thermal properties. Agreement between calculated and measured time-temperature curves obtained, for example, with a constant physical property analytical model however was not satisfactory. The agreement between calculated and measured values was not improved by the introduction of a shine-through radiative term that was independent of the conductive transport. Numerically-derived time-temperature curves that used measured k/sub a/(T) and C(T) and no adjustable parameters differed as much as 1 K during the first 600 seconds of a transient. Agreement between measured and calculated transient screen temperatures to better than +-0.25 K was achieved by treating the C of the screen heater as an adjustable parameter. The analysis of transient data for the two reference materials is complicated by the presence of a heat of transition in the temperature range of interest. The effects of coupled conduction-radiation transport have not been included in the present analysis and this may be the reason for difficulties in describing the initial segment of the time-temperature curves. The results and analyses presented in this paper identify a need for chemical characterization of thermal reference materials. The exact composition of the materials used in this study was not known and this made the thermal analysis more difficult. 20 refs., 4 figs. (ERA citation 10:037346)