The point that Rich is making on his site is anything shiny can reflect
radiated heat back to the tubes. The tubes are the source of heat. Some of this
heat is conducted to the elements of the tube. Much of the heat is radiated in
the form of infrared radiation. You want to remove the heat from the source
(the tubes) as effectively as possible. If it all goes away, that great. That's
what the fan is trying to do. If some of that radiated heat is reflected back
at the tubes, the tubes are going to get a little hotter. How much hotter, I
don't think anyone has measured it. But, if one paints the walls black, more of
that radiated heat is absorbed and not radiated back to the tubes. The
blackened walls get a little warmer, but the air from the fan passing by the
walls removes it without letting it get back to the tubes.
Mike K6aMDS
>
This is true, so a black panel between the hot thing (tube) you are
trying to keep cool, and a cooler thing ( outside of the cabinet or
other lower temperature area) makes sense if radiant cooling is a
significant portion of the heat flow from the hot things.
If the panel is in between two hot things (a pair of tubes) and is there
to direct air flow, then the color of it is not going to matter at all,
unless it has a way to make it a lower temperature than what is on
either side of it. If the panel was thick enough to have a high thermal
conductance and is also thermally coupled to a heat sink or other heat
exchanger that could keep it's temperature cooler than the two tubes on
either side of it, then it might be some advantage to have it black.
If it is just a thin piece of metal with hardly any low resistance
thermal connection to something lower temperature, it is not going to
absorb any heat from the tubes regardless of it's color. The
temperatures on either side of the panel are equal (if the tubes are at
the same temperature) so there is no heat flow.
DE N6KB
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|