>X-Sender: tcolson@nuvomedia.com
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>Date: Thu, 13 Nov 1997 09:41:28 -0800
>To: kenji! <kenji@nuvomedia.com>
>From: Tom Colson <tcolson@nuvomedia.com>
>Subject: Thermos(tm)
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>
>Why Kenji's Thermos(tm) Keeps His Coffee Hot and His Margaritas Cold
>
>Heat is transferred by 3 different mechanisms and the Thermos(tm) breaks
>two of them.
>
>Conductive heat transfer occurs when two materials at different
>temperatures are in direct contact with each other. The rate of heat
>transfer depends on the thermal conductivity of the materials, among other
>things. Since the space between the wall of the Thermos(tm) is filled with
>almost vacuum and the almost vacuum has low thermal conductivity, little
>conduction occurs.
>
>Convective heat transfer occurs when bulk motion of two different fluids at
>different temperatures occurs, mixing hotter with colder. The rate of heat
>transfer depends on the heat capacity of the fluids, among other things.
>Since the almost vacuum between the walls of the Thermos(tm) has low heat
>capacity, little convection occurs.
>
>Radiant heat transfer occurs when two different objects of different
>temperatures are in line of sight of one another, even with vacuum in
>between. Thermos(tm) couldn't figure out how to deal with this one.
>Luckily, physics dictates that when the temperature difference between the
>objects is less than a few hundred degrees celcius, radiant heat transfer
>is negligble. Safety tip: don't use your Thermos(tm) for fluids that glow.
>--
>
>Tom Colson
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