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Re: [Electronics_101] Re: Anyone know about Thermal coupling?

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  • Stefan Trethan
    On Thu, 29 Jun 2006 16:55:14 +0200, Bob Hyland-PMP ... You are right, i had the same thought soon after suggesting that. It would be best to put the peltier in
    Message 1 of 9 , Jun 29, 2006
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      On Thu, 29 Jun 2006 16:55:14 +0200, Bob Hyland-PMP
      <BobHyland@...> wrote:

      >
      >> If you want the whole box cold i would put the peltier on the
      > bottom
      > Challenge on the bottom is then heat redistribution and air flow.
      > The heat would be generated underneath the unit, tending to heat it.
      > And, then I would need a stand / legs / something to ensure proper
      > airflow to the heatsink & fan.
      >

      You are right, i had the same thought soon after suggesting that. It would
      be best to put the peltier in the side, maybe the lid.


      >> and use thicker material throughout. If one wall is enough A and B
      >> should both work assuming that you get good contact with the
      >> components.
      > Ok, so you are suggesting that I do not need to replace the wall of
      > the unit. Instead, I simply attach alluminum with a larger cross-
      > sectional area (i.e. one that is thicker) to the side and make sure
      > there is a good thermal connection to the tin. Do I have that
      > correct?

      You do not necessarily need to replace it, but it is hard to get good
      contact on large surfaces, especially when dealing with thin materials.
      How about cutting a hole in the tin the size of the peltier and putting
      the thick aluminum inside the tin? You could also bend a L shape to cover
      the side and bottom, or a U shape to cover 3 sides...

      >
      >> If you only need the inside of the box cold put some XPS foam
      > Any idea where to get this locally?

      Building supplies for example. Normal styrofoam will work also, but i
      prefer to use XPS instead of EPS because it does not have any beads. This
      makes it easier to make smaller structures from it. If you really want to
      use PU foam in a can you could also use that to isolate the tin, put it in
      a larger box and fill the gap. I'm not a great fan of PU foam cans because
      of the clogging issue and the Xn rating. Also, those foams can form quite
      large bubbles leading to bad thermal isolation.

      >> all around the outside to avoid heat.. ahem.. cold loss.
      > Ok, I guess that would be something like "Heat Intrusion"?

      Probably. Make two layers of isolation with the seams in different places
      to avoid any leak there.

      ST
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