[Amps] making sinks black

[Dr. David Kirkby]

S. J. Blackwell wrote:
> Tom,
> I agree with your statements below. The color has very little to do with 
> heat sinks that we deal with.
> 
> Most heat sinks now days have relatively tall closely spaced fins. For 
> practical porposes the heat sink, from a radiation stand point, could be 
> looked at as a block of material the length, width and height that would not 
> include the fins. The only radiation heat loss for all practical purposes 
> would be from top, bottom and sides. Little radiation loss from the fins as 
> they face each other.

> They are clearly designed for an air flow over the 
> fins. Paint, in my veiw, would impede cooling, no matter what color. Anodize 
> is another matter. Anyone for black anodized bottom, pink fins except the 
> outside surfaces of the first and last fins and the fin edges? Arrange the 
> heat sink for good convection, if that is not sufficient, then blow it, pink 
> or not. It doesen't matter. For all practical purposes the black body does 
> not include the fins.
> 
> 73
> Sam, W5LU

I think you will find the *radiation* from a heat sink is going to be 
very small indeed. It will not depend the slightest on airflow.

*Convection* will be the dominant method of loosing heat, which will 
depend on airflow.

Simple explanation at:
http://www.mansfieldct.org/schools/MMS/staff/hand/convcondrad.htm

More complex one at:
http://sol.sci.uop.edu/~jfalward/heattransfer/heattransfer.html

No doubt 100's more explanations on the web too.

As such, I'm not convinced blacking the heat sinks will do much for 
cooling, especially if there is even a very small fan nearby.

-- 
Dr. David Kirkby