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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-469-4

ISBN Online: 978-1-56700-470-0

Second Thermal and Fluids Engineering Conference
April, 2-5, 2017, Las Vegas, NV, USA

EXPERIMENTAL INVESTIGATION OF COMBINED CONDUCTIVE AND RADIATIVE HEAT TRANSFER IN SILICA AEROGEL COMPOSITE AT HITH TEMPERATURES

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DOI: 10.1615/TFEC2017.emi.018068

Аннотация

Silica aerogel composites have shown strong development in numerous practical insulation applications, the knowledge of their conductive and radiative properties is of primary importance in the process of designing and evaluating the insulation systems. This paper presents an inverse method for predicting the temperature-dependent true thermal conductivity of highly porous silica aerogel composite from measured transient temperature data for temperature from ambient temperature to elevated temperature up to 1100 K and various gas pressures between 0.01 Pa and 100 kPa. It was achieved by combining a forward method solving coupled conductive and radiative heat transfer and an optimization method based on genetic algorithm (GA). The radiative properties used to solve combined conduction and radiation were theoretically predicted from Lorenz-Mie theory. The true thermal conductivities fell within 0.013-0.031 W/(m·K) for the temperature and gas pressure ranges considered, increased nonlinear with increasing gas pressure, and increased almost linear with increasing temperature. The contributions of radiative and conductive heat transfer in silica aerogel composite were predicted form the predicted radiative properties and the retrieved true thermal conductivity, the radiative heat transfer contribution increased with increasing temperature, but decreased as the gas pressure increased. Heat conduction always dominates in the SAC specimen for all gas pressures and specimen temperatures investigated.