The use of fine powders to provide high thermal resistance for high-temperature industrial applications and commercial or residential appliances could provide significant energy savings. Theoretical considerations show an apparent thermal conductivity below 0. 0072 W/m multiplied by (times) K (R value equals 20 ft**2 h degree F/Btu/in. ) can be achieved by a system that blocks radiation by use of small diameter particles and increases the mean free path in the gas phase by reducing pressure. A model that includes radiative and conductive heat transfer is used to discuss the requirements for a high thermal resistance material. Thermal conductivity measurements are reported for powders with particle diameters from 7 nm to 500 mu m at pressures from t to 1. 0 multiplied by 10**5 Pa and temperatures from 296 to 339 K.
|Number of pages||13|
|Journal||High temperature science|
|Publication status||Published - 1 Apr 1984|
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