Sunny Boy in the sun? [RE-wrenches]

Dean T. Newberry deant at dcn.org
Mon Sep 29 23:26:53 PDT 2003


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Hi y'All,
In the Hydronics industry we learned that radiant energy reflection and 
emissivity are roughly inverse.
    The rule of thumb is the surface shinyness is the factor governing 
reflection and emissivity, not the color.
A shiny surface regardless of it's color will reflect 90% of heat, a 
flat surface will absorb 90% of  the heat.  For example, a sheet of 
shiny aluminum foil will reflect 90%, paint it with flat latex paint and 
it will absorb 90% of the heat. If you use white latex, both will 
reflect 90% of the light.
    Color is the factor for governing the absorbtion or reflectance of 
light, ie white reflects 90%, black absorbs 90% of light. The heat sink 
in my PC is anodized black, the one in my MAC is anodized clear.
I suspect the color of the heat sink was decided for other reasons than 
the factors listed above.
    My reasoning leads me to suspect a clear anodized heat sink on a 
Sunnyboy would perform slightly beter in direct sunlight than a black 
heat sink.  The recommendation is to put the SB in the shade,  so color 
is irrelevant for performance. Black looks nicer against red, blue, and 
yellow.
    I'll bet John Berdner has something to say about all this.

See y'All later  deant

sunwise wrote:

>If I remember correctly, a black surface is not only better at receiving
>radiant heat energy (in the sun), it is also better at dissipating heat
>via radiant heat loss/exchange.  I would assume this is why we tend to
>see flat black heatsinks.
>
>Kurt Nelson
>SOLutions
>
>-----Original Message-----
>From: Jason Fisher [mailto:jfisher at nahbrc.org] 
>Sent: Monday, September 29, 2003 8:12 AM
>To: RE-wrenches at topica.com
>Subject: RE: Sunny Boy in the sun? [RE-wrenches]
>
>A question I've often had when facing this problem is whether or not 
>black is really the best color for the exposed heatsinks. Wouldn't a 
>silver or clear coating lesser the effects of direct sunlight on the 
>performance or is black simply the best at dissapating the heat?
>
>Jason Fisher
>Aurora Energy
>
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