On optimizing the experimental setup for estimation of the thermal conductivity of thin films

Abstract

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The aim of this study is to show the optimal arrangement of a measurement system for estimating the thermal conductivity of thin flms from temperature profles. For this purpose, two diferent experimental setup systems, with square and circular cross sections, were designed to estimate the thermal conductivity of thin flms and, in particular, of two ion exchange membranes. Both systems were placed horizontally and vertically in order to evaluate the best orientation to more accurately determine thermal conductivity. A three-dimensional numerical simulation was performed using Comsol Multiphysics to predict the heat fow and temperature gradient and to evaluate the efect of the geometry and the orientation on the contact resistances. Each system was frst calibrated without the membrane inside in order to estimate all the necessary thermal properties of the diferent materials of the model. Next, the membrane was placed inside the model, so that the model now includes the thermal conductivity of the membrane as the only unknown parameter. The numerical results were compared with the various measured temperature profles to estimate the thermal conductivity. The thermal conductivity values of the well-known Nafon 117 membrane and other thicker membrane were determined. A very good agreement with reliable literature values was obtained. The approach presented here, combining experimental and simulated temperature profles, may provide the basis for a practical alternative to better estimate the thermal conductivity of thin flms.