Cooling for Underwater Monitor Housing

[David Dincer]

Hi,

I have an underwater monitor housing made out of carbon fiber and an acryllic Glass on the other side.
Over time the monitor heats up. I guess carbon fiber is a bad heat conductor :(. the Acryllic glass is almost 1cm thick. Does anybody have an advice on how to cool something like this from the inside?
Grateful for every tip or idea! Cheers!

 

[.Scott]

In this kind of enclosed space, the best solution is usually conductive cooling.
Attach the hottest parts of the monitor to a copper plate that is attached to the acrylic with one or two copper bolts.
The copper bolts will pass through the crosses through the acryllic and into the water. On the water side, use another copper plate attached to those same bolts.

 

[David Dincer]

In this kind of enclosed space, the best solution is usually conductive cooling.
Attach the hottest parts of the monitor to a copper plate that is attached to the acrylic with one or two copper bolts.
The copper bolts will pass through the crosses through the acryllic and into the water. On the water side, use another copper plate attached to those same bolts.

Nice idea! Just to clarify: You would drill a hole through the acryllic glass for the bolts ?

 

[.Scott]

Nice idea! Just to clarify: You would drill a hole through the acryllic glass for the bolts ?

Through the acrylic or through the carbon fiber. Before drilling the holes, choose your bolts - inexpensive copper bolts don't come is a great variety. Brass or bronze is not nearly as good as copper. If corrosion of the metal plate in the water is going to be an issue, you can substitute an aluminum plate.
Obviously, after drilling through the air/glass barrier, you will need to seal it. So pick flat spots in the material to drill through and use the nut/bolt combination to get a snug fit - perhaps supplemented by teflon washers.

 

[Tom.G]

perhaps supplemented by teflon washers.

For more than moderate tightening, always use a compliant material, both sides, against hard plastic, ceramic, glass, etc., -- anything that fractures. (I'm not familiar with the characteristics of Carbon fiber so can't make any definite statement there; but it won't hurt.) Use sealing washers (metal washer with a layer of rubber bonded to one side), O-rings, any soft polymer (Teflon, rubber, Nylon, etc.). The object is to avoid any localized stress concentration on the fracturable material. If you are going for full immersion in water, remember that threaded fasteners leak fluids down the threads so you will need to seal any exposed threads. Silicone rubber comes to mind for light-duty use but it is slightly porous, and, since it releases Acetic Acid during curing, it reacts with some metals, i.e. Aluminium.

p.s. When correctly sized, sealing washers have a tight fit between the rubber and the threaded fastener. When the joint is tightened, the rubber is forced into the threads giving a moderately decent seal. There are also nuts with an O-ring embedded in one surface. They are not commonly available and don't seal the threads.

 

[David Dincer]

I also shouldn't use my vacuum pump I guess. Air is a good heat conductor right? Vacuum not. Just a little low pressure to keep the seals tight.

Thanks so much guys!

 

[.Scott]

I also shouldn't use my vacuum pump I guess. Air is a good heat conductor right? Vacuum not. Just a little low pressure to keep the seals tight.

Thanks so much guys!

Air is better than a vacuum, but you should be able to get the copper path to work with a vacuum as well.