[Amps] Fan for SB220

[Ken Brown]

>  Black  both absorbs and 
> radiates heat more efficiently than any other color.
>  
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