Good thermal insulation in a tight space

[joncot1812]

In trying to find a solution on google I stumbled across this forum and think I might have to stick around. I'm a youngster, junior in college and managed to land a part time job as an ME working for a bunch of EE's trying to build a ridiculously complex and quite irrational device that doesn't really have any real world application, but it's a clever idea and has been quite the learning experience so far. But to my question. I figured this to be the best place to ask. I'm trying to find something I can use for insulation that is 1/8" max 1/32" minimum, is somewhat flexible as my diameters range from 1.75" to 2.5", and has a k factor of .05 at the most, .03 ideal. And air isn't much of an option as this will be submerged in water 100'- 300' depth and finding room for sealing will have to change the current design. Thank you for your help whether it be an answer or a point the right direction.

 

[edstimator]

Sheet mylar? Just throwin out there

 

[IRstuff]

Well, you're asking for a lot. At the minimum depth specified, the water pressure is at least 60 psi, and the thermal conductivity specified would result in mostly squishy materials, like hollowfill or aerogels. See:

http://www.goodfellow.com/catalogue...2xgQzAbJATbl&ewd_urlNo=GFCat24&type=30&prop=6

for a table of thermal properties. Nonetheless, the water pressure would compact some of the materials on the list, thus nullifying their insulative properties.

Note that based on your description, the insulative properties are likely to be compromised, since there's ample room for water to intrude and directly contact the interior object.

TTFN

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[joncot1812]

Yea I know, my boss wanted me to figure out, but I didn't think I was going to find anything. He keeps asking ridiculous things and every time I simplify the design he says it's a good idea then over complicates the process and it becomes implausible again. For example we are using 2 nylon washers, 2 o-rings, 2 metal washers, 3 nylon spacers, two nuts, and 2 ring connectors to make a wire connection between a 3/4" plate to make sure there is no short between the wire and the plate. Even though there is .063" rubber insulation around the wire and the wire doesn't move at all.

My cars go "bdoom vroom pop pop whistle", my music goes "bvvv wub wub bvvv", and my hearing goes " "....

 

[cloa]

Just for fun- how voltage is running through this wire?

 

[btrueblood]

Foamed silica can take a fair bit of compressive stress, and is one of the lowest thermal conductivities for the more-or-less monolithic ceramics.

 

[joncot1812]

12V system.

My cars go "bdoom vroom pop pop whistle", my music goes "bvvv wub wub bvvv", and my hearing goes " "....

 

[patprimmer]

bt

I think he also wants flexibility. Maybe hollow glass spheres in silicon rubber or cast urethane? I think the requirements are impossible.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[joncot1812]

Found my solution. McMaster sells polystyrene in 1/32" sheets, it's hard, can easily be molded, an has a k-value of .08W/mK.

My cars go "bdoom vroom pop pop whistle", my music goes "bvvv wub wub bvvv", and my hearing goes " "....

 

[patprimmer]

Polystyrene is not somewhat flexible. In fact it is quite rigid and brittle and really poor to UV light if that matters.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[IRstuff]

I think the OP simply needs the material to conform to the shape of the insulated object. That can be done with flexibility, or by molding. Polystyrene was one obvious choice for molding. Being hard, it's also reasonably able to survive the pressure.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[joncot1812]

Yea, I can use heat to mold the sheets. I've been looking around the forums and I like this place. It's better than watching guys bicker about his Honda being faster than his Mustang, but his mustang can be faster and is a much nicer car. Those are the only forums I'm ever on. There seems to be mildly educated people trolling these pages.

My cars go "bdoom vroom pop pop whistle", my music goes "bvvv wub wub bvvv", and my hearing goes " "....

 

[patprimmer]

Polystyrene really is quite fragile. If you are prepared to mould the part, I would use acrylic, polycarbonate, ABS or a prepreg FRP, depending on the environment of use. Even a hydro epoxy putty. The type plumbers use to repair cast iron pipe.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[Compositepro]

Pat's suggestion of glass microspheres is a good one these can be mixed with silicone rubber or epoxy resin to make syntactic foams which are strong and will have insulating properties as good as any other foam. Syntactic foams are used for bouyancy in submarines. You can get glass microballons at hobby shops that cater to model aircraft builders. Thin polystyrene foam will collapse under pressure or saturate with water.

 

[patprimmer]

Compo

It's interesting that I have presumed he meant solid PS and you have presumed he meant PS foam.

I wonder who is correct and that in no way implies I think it was me. It implies a layman has given insufficient information and we both made assumption as to what he meant vs what he said.

Anyway, either way, glass bead in a thermoset resin could work for him.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

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[joncot1812]

I was looking at solid sheets. My boss decided it was too elaborate again and I had to redesign it again. I would be more descriptive on the product I'm working on, but it's kind of hush hush at this point.

My cars go "bdoom vroom pop pop whistle", my music goes "bvvv wub wub bvvv", and my hearing goes " "....