# Tag Info

## New answers tagged thermal-conductivity

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Simple answer: tenuity. Thus, vacuum is the best isolator (remember double window - attempt to save the heat in the house or vacuum flask, thermos) cause it hurdles to transfer kinetic energy via particles, i.e. the more space between particles the less collision between them the less heat transfer then. These principles mostly underlie aerogel class ...

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Two ideas are especially to the heat isolation properties of aerogels: (i) aerogels are mostly gas and (ii) the Knudsen Effect. Clearly, heat isolation is achieved by blocking heat transfer paths: these are the paths of convection and conduction at the temperatures of interest (radiation also becomes important at higher temperature). Any material barrier ...

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Take a look at a counter flow heat exchanger. At all points in the heat exchanger there is a temperature difference/gradient.

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It turns out that the answer is pretty straightforward. Power is the force dotted with velocity, so it should make sense that the energy current (a power in a direction) takes a similar form. For an elastic medium, this vector is the product of the stress tensor with the velocity vector (source). The result is the heat flux (current) -- the equivalent of the ...

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From my heat transfer textbook by Cengel and Ghajar, they propose that you use the average thermal conductivity value as you specified in your last equation: $k_{avg} = k(T_{avg}) = k_0(1+\beta(T_a+T_b)/2)$ where $\beta$ and $k_0$ are material properties, assuming that the material thermal conductivity follows a linear function w.r.t temperature. You ...

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