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Mon, 22 Nov 1999 11:22:36 -0800 |
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Dear all ...
I made a mistake with my posting. The information
I posted deals with heat transferred through a solid.
What you want is heat transfer from an exposed surface
to ambient by convection. By looking in an old 1992
iTi Ferrotech catalog, they have a great section in
the back that addresses this and many other thermal
issues. I cannot locate this company. Anywho, they
give the equation for Heat Conducted From Surface to
Air. It's the following ...
Q = h * (T1 - T2) * A
h = Heat Transfer Coefficient
T1 = temperature in degrees C
T2 = temperature in degrees C
A = area in square meters.
h is given several values given still or turbulent air.
Still Air h = 23 to 28
Turbulent Air, h = 85 to 113
One square inch is 0.0064 square meters.
Dissipation in Watts for 0.0064 square meters,
an ambient of 20C and a raised temp of 40C
(a temp differential of 20 degrees C), this
works out to be 2.94 Watts. Worst case it
and say 3 Watts.
For some strange reason, this sounds about right.
Thus, two square inches would be twice that
or 6 Watts.
Regards, Doug
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