Thermal Diffusivity of Powder Insulation
The steady-state heat flux into a cryogenic vessei is determined by the thermal conductivity of the insulating material In addition to knowing the steady-state fiux, it is frequently important to know how long it takes to approach equilibrium after the vessel is filled with liquid. The transient behavior is determined by the thermal diffusivity of the insulation and, as far as is known, has not been measured for powders commonly used for cryogenic insulations. Studies have, therefore, been made of the transient behavior of such powders as carbon, silica-magnesia, and a silica-aluminum mixture. The diffusivity obtained in these studies is temperature dependent, and with reasonable assumptions about the temperature dependence of the specific heat the derived values of thermal conductivity are in fairly good agreement with steady-state values.
KeywordsThermal Conductivity Thermal Diffusivity Transient Behavior Temperature Dependent Thermal Conductivity Dependent Thermal Conductivity
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