On 9/9/99 23:27 Ocie Ward ([EMAIL PROTECTED]) wrote:
>Well, I just happen to be a Physicist, but
>unfortunately not a very good one ;) I don't do much
>with chemical makeup, which would determine the heat
>dispersion capabilities of various materials, but I do
>have a couple of thoughts. One, both aluminum and
>copper are excellent conductors. Two, ceramic
>materials are excellent insulators. I am not trying
>to contradict observations that a PB runs cooler on a
>tile counter (experimental evidence speaks for
>itself), but I would think a surface that conducts
>heat away from the machine would be far better than a
>surface that , in theory, prevents heat transfer.
Well, having degrees in both engineering and physics, I'm not sure I'm
much better ;-) --but let me make a stab at a hypothesis. Although tile
and marble are insulators, they have a high heat capacity and can absorb
a lot of heat from the PowerBook with only a modest increase in their own
temperatures, depending on how long the PowerBook is used. When you make
pastry you roll it on a polished stone slab, not a stainless steel
countertop, because the stone absorbs the heat generated by the rolling
but maintains a lower temperature that helps keep the shortening from
liquefying, so the pastry stays flaky. Of course, the heat from the
PowerBook is concentrated on a smaller spot, and I imagine that yes, it
does permeate the rest of the mass relatively slowly.
The conductors transfer heat from the PowerBook faster, but unless
relatively massive need to radiate the heat into the air (a poor
conductor with low heat capacity) and the surface that they're resting
on, or they're going get as hot as the PowerBook.
Depending on the design and mass of the heat sink, it seems like either
one can be an effective aid in keeping the PowerBook cooler. Under my
hypothesis, the best system would be a sheet of copper or aluminum on top
of a block of stone or tile. You could get quite aesthetic matching up
different colors of stone and anodizing. And if you could put some kind
of fluid layer underneath the metal, that circulates through channels in
the stone. you'd really have something :-).
BC
"An engineer is a man with a mind so narrow he can look through a keyhole
with both eyes."
-- L. N. Smith
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