heat sink surface area calculation

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hi every body

i am working on power electronics projecs, as per my knowledge , for dissipation of heat in power components everybody uses heat sinks, and heat dissipates with respect to thermal resistance of heat sink, and thermal resistance of heat sink depends upon surface area of heat sink , and surface area is total exposed area of heat sink, if i am right tell me, what is right method of measuring surface area of heat sink,because heat sinks are available in different shapes, if i miss any point, kindly give me additional information also, because i want to go thoroughly in my concept

thanks
venus electronics
 

For measuring surface area, you would want to use a rule and possibly a pocket calculator, strictly spoken.

Besides surface area, there are other parameters affecting the thermal resistance, as horizontal/vertical orientation of surface, micro and overall shape, forced or natural convection air flow. Relying on thermal resistance specification from manufacturers will most likely achieve more accurate results. You'll find, that even detailed thermodynamics text books are giving rather rules of thumb than exact formulas for this problem. So an empirical measurement with your final design will be necessary.
 

Look at manufacturers catalogues and see the figures for your kind of shape. Surface finish is also importent, hence the matt black finish on the better items. Do you understand thermal resistance?, most important number of all.
Frank
 

Keep in mind that the ultimate performance of a heatsink will probably depend more on airflow than on shape and size.
 

dear sir
you have tried to give me perfact guidence, but still am confused. at presnt i am comparing my heat sink's data with avidthermalloys.com's data. that way i am calculating thermal resistance of heat sink,
venus electronics
 

A heat sink is useless without airflow.

Heat sinks with equal actual area, can differ a lot in
how effective they are, as fin or prong arrangement
can affect airflow (especially convective, but forced
as well). Both net flow, and distribution.

I think you're better off comparing data than calculating.
Because you have no idea what the calculations assume
or neglect, relative to reality.
 

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