aluminum U channel vs. flat bars for LED heat sink
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Old 07-20-2013, 10:55 PM   #1
the_deeb
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aluminum U channel vs. flat bars for LED heat sink


I'm building a relatively low-density LED fixture and was planning on using aluminum U channel as a heatsink. I'm planning to have 14 Cree XT-Es spread out on a 48" strip, and the strips are going to be part of an open fixture with passive cooling (no fans).

I was planning on using aluminum U channel that is 2" X 1/2" X 1/8" thick, but I also have access to some cheap aluminum flat buss bars that are 2" wide and 1/4" thick.

It seems to me that the U channel has a larger surface area, which would be better for heat dissipation away from the fixture, whereas the flats have more material which would be better for absorbing heat away from the LEDs. I'm not sure which property is more useful.

The flat bars are cheap enough that I could probably double up on them and use half as many LEDs on each bar.

So which option do you think is better? 1/8" U channel or 1/4" flat bar?
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Old 07-20-2013, 11:53 PM   #2
Legot
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You're at a point where either option would fulfill your needs perfectly. Choose the one that looks better. Its true that with the thinner U channel the fixture as a whole will stay slightly cooler than the 1/4" flat, but the LED junction temprature will not be significantly cooler with either.

I would go with the flat just because IMO, it's easier to make look good. On my light, using 14 3w cree's I actually used a 1/32" pattern mesh and its staying room temp (about 82F) perfectly with no active cooling.

What I'm seeing with most aquarium LED fixtures is really excessive cooling. Unless you're actively keeping the leds a fair amount below room temp (peltier or chilled substance cooling, etc) there won't be any noticeable difference in the lifetime of the diode, and using systems like that removes the space benefits and cost savings of LED!
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Old 07-21-2013, 12:57 AM   #3
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I was just at the hardware and have decided on some H channel Aluminum for mine set off the hood's lid by a small peice of H channel.
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