Commercial home amps have internal heatsinks with very thin fins. Yet heatsinks from Jaycar etc have rather thick fins. Which actually works better, thin or thick fins??
- posted
18 years ago
Commercial home amps have internal heatsinks with very thin fins. Yet heatsinks from Jaycar etc have rather thick fins. Which actually works better, thin or thick fins??
"S Roby"
** More description needed.Commercial amps have all kinds of different heatsink designs.
** Depends how they are made, ie extruded, machined or fabricated.The ones used in domestic amps are the very lowest COST for their job.
.......... Phil
On Mon, 24 Oct 2005 05:39:52 GMT, snipped-for-privacy@gooble.gooble (S Roby) put finger to keyboard and composed:
I would expect that the heatsink with the most surface area per unit volume would work best, all other things being equal.
-- Franc Zabkar
Please remove one 'i' from my address when replying by email.
**There's no one, correct answer. The heatsinks you've seen usually take two forms. 1) A slab of flat aluminium bar, is (for want of a better term) 'planed', until very thin strips of metal are formed, curved and away from the bar. The central bar is reasonably thick and there's lots of surface area, so it works well. 2) A central bar of aluminium has an accordion shaped piece of aluminium bonded to it, with approximately the same effect as #1.
Thick fins allow more thermal mass and, in some cases better heat transfer.
-- Trevor Wilson www.rageaudio.com.au
forms.
until very
is
bonded to
Trevor,
what is the significance of thermal mass in a heatsink? With constant dissipation isn't thermal mass irrelevant?
-Andrew M
**Sort of, however:
-- Trevor Wilson www.rageaudio.com.au
On Tue, 25 Oct 2005 19:53:42 +1000, "Andrew M" put finger to keyboard and composed:
forms.
until very
bar is
bonded to
dissipation
Heatsinks move heat in three ways - conduction, convection, and radiation. For a given geometry, a heatsink's mass determines its conduction efficiency, its surface area its convection efficiency, and its radiation efficiency is improved by anodising or painting it. For a typical finned heatsink there is an optimal spacing below which efficiency begins to decrease. My memory is not good enough, but I believe the reason involves some principle of fluid dynamics, maybe drag. In any case closely spaced fins more readily collect dust.
If I were you I'd search for app notes and datasheets from companies specialising in this field. I expect heatsink design is more of an empirical exercise than a theoretical one.
This article looks useful:
-- Franc Zabkar
Please remove one 'i' from my address when replying by email.
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