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Thermal Management : How to go fanless in a small space?

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ebastler:

--- Quote from: excitedbox on April 29, 2019, 12:47:17 am ---Trying to think outside the box here. Could you stuff it full of a copper sponge type material and add vents at the top and bottom?

--- End quote ---

That's rather thinking "inside the box", isn't it?  ;)

But I am afraid it will not work. The surface area of your copper sponge will not be comparable to the required approx. 2 K/W heatsink. And at the same time the sponge will inhibit airflow enough to stop most of the "chimney effect" you hope for.

excitedbox:
That is what I was worried about. Maybe a brilliant pad type copper mesh would let more air through. As others have said there is probably no way around a fan though. Keep in mind a heavy heat sink hanging off the front will act as a lever pulling on your head and strain your neck.

Marco:
That's why it's interesting to make a heatsink which uses PGS for fins, it could in theory be very light.

3roomlab:
edit post #19 updated, the nearly condensed method in LTspice
the other earlier simulations are full of errors
which boils down the entire goggle mod to, having a fan or not. a fan is a must have
by adjusting the LTspice sim which includes convection, the range of surface to air resistance is from 25 to 38C/W.cm2.
by quadrupling the key internal surface areas, the internal disspation resistance goes down to 6.6 to 9.3 C/W.cm2.
but still you need a fan

with surface emissitivity over 0.8, the heat radiation and convective loss is nearly similar. they curve up at nearly the same rates. at 20C diff, the loss rate thermal resistance can go down below 5C/W

daslolo:

--- Quote from: 3roomlab on April 29, 2019, 05:00:11 pm ---the first plot is the rate heat is moving to the last 2mm
the 2nd plot is the air heat up in 1s. the PGS is still trying to play catch up, but the copper has already more or less stabilized the entire sink temperature.
PGS70 is $0.32 per cm2 vs cu 1mm is around $0.05 per cm2. I think based on simulation, the thinnest Cu to beat PGS70 by a good margin is around 0.4mm. at this, the PGS is really for a very niche use.

--- End quote ---
0.4mm cu base with how long fins?
What's the weight of both solutions?

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