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Old Jul 31, 2009, 05:07 PM
Drydock Captian
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Spanaway, WA
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a color that uses alot of metallic materials (like silver) will be your best for heat transfer. The solid colors will act as an insulator since they are a form of plastic and have poor heat transfer properties. Using a zinc rich primer like you would use while MIG welding would work good too since it is made up of mostly powdered zinc. For the best cooling I leave them bare, but then you have to worry about corrosion. Your call there.

Massey
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Old Jul 31, 2009, 05:33 PM
Grumpa Tom
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United States, CA, Los Angeles
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http://www.newton.dep.anl.gov/askasc...0/phy00156.htm

What color are car and truck radiators?
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Old Jul 31, 2009, 05:44 PM
USA'd ex Brit
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Quote:
Originally Posted by Kmot
http://www.newton.dep.anl.gov/askasc...0/phy00156.htm

What color are car and truck radiators?
Black...

But that's heat transfer in to air, not in to water..
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Old Jul 31, 2009, 05:49 PM
Grumpa Tom
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Don't think it matters. According to the scientists on the link I provided,

" darker colors are
better absorbers of light and thereby become better radiators of heat. "
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Old Jul 31, 2009, 06:14 PM
no wings any more, just dust!
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stoke on trent
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Quote:
Originally Posted by Shaun Hendricks
Black is heat absorbant, white/silver is a radiant. I'd go for metallic silver like a chrome. Besides, you can claim you have "Chrome Pipes"...
BLING!!

Pimp my boat
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Old Jul 31, 2009, 06:22 PM
3 Blades to the Wind
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Well, them darned rocket scientists made the space shuttles heat radiators polished silver to reflect any incident sunlight and to radiate as much heat as possible. While not totally the same principle (since there's nearly no air at the altitude the shuttle runs) it does touch on a thermodynamic concept that applies to a tug and not a car or truck.

Also chrome is the 'color' of it's surroundings so in darker water it will radiate the heat into the water and reflect any attempt at the water trying to reflect the heat back into the radiator. This is why I suggested light colors.

A car/truck radiator uses a more transient fluid stream (air) and thus it does not linger long enough to radiate any heat back into the radiator (the fan or motion moves it past a vertical surface). In that case, black would work better because it is absorbing as much "coolness" as possible. Heat is relative to given temperature.

A tug could be sitting in it's own hot water for a given time if the propulsion isn't running (and it's a long horizontal surface so you'd have to have decent movement to clear the fluid from the surface) and thus you'd not want to get any heated water back into the system. So I still espouse a chrome/metallic polished coloring. You'd have to test each idea to see which actually works the best.

I do understand the black concept though. You are 'absorbing' the coolness of the water, but in an odd way it might not work as well being paint...
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Old Jul 31, 2009, 06:31 PM
no wings any more, just dust!
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they look to be the same color as the surrounding hull on both pics, I presume they're covered in antifoul.
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Old Jul 31, 2009, 08:48 PM
Grumpa Tom
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What color would heat exchangers be on a submersible at 3000' depth where there is no visible light?
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Old Jul 31, 2009, 09:13 PM
NeverAgainVolunteerYourse lf
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I think that they should be same as anti fouling colour, heat transfer is by conduction not radiation so unless the paint is insulating the pipes it wont make much difference. It wont matter what colour the paint is,
the second law states of thermodynamics states simply "energy systems have a tendency to increase their entropy rather than decrease it." This can also be stated as "heat can spontaneously flow from a higher-temperature region to a lower-temperature region, but not the other way around."
so heat reabsorbtion is impossible unless the "hot side" becomes cooler than the surrounding water
Nick
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Old Jul 31, 2009, 11:39 PM
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Bucharest, RO
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To add a bit to what Nick was saying: because we are talking radiation, there is no comparison with the full scale boats, as the surface in contact with the water is far greater. If you get to high temps, your radiator will create a local microflow that will draw cooler water from beneath...
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Old Aug 01, 2009, 12:46 AM
Crazy Canuck...in Dallas
Mckinney
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colour doesn't matter in liquid

it's the contact with the coolant/surface area, etc...

i vote to paint it bottom colour, silver or black only apply to air cooling(i'm a volkswagen nut(re: air-cooled car)the factory painted everything black, but that's for air cooling....

you're building a liquid to liquid cooler, liquids, like water, have a much higher coefecient(?) of heat(meaning they can absorb alot of heat)than air, they can be more efficient, but this means it the more "tubes" you have, the more surface/contact area you have, the more heat transfer.
the colour of the paint will have no influence on the performance....in fact, the less coating may be best, with the lack of "insulating" paint.
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Old Aug 01, 2009, 06:19 AM
Registered User
United States, ME, Bar Harbor
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I f they were on areal boat they would be painted antifoul. The pipes would otherwise soon be covered with growth, especially mussels, which would insulate them, reducing their efficiency.
Jonatahn
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Old Aug 01, 2009, 11:16 AM
Submarines, etc.
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Arvada, Colorado
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kmot,

you don't need heat exchangers at 3000', it is so cold that it is like being in a refrigerator.

Alvin crewmembers that regularly dive in the bahamas wear sweaters, sweatpants, and wool socks.
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Old Aug 01, 2009, 11:21 AM
Grumpa Tom
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United States, CA, Los Angeles
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Personally, I would polish the crap outta it and make it a nice shiny piece of BLING on the underside of the boat. Would be a shame to cover up all that work.
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Old Aug 01, 2009, 12:17 PM
Boats on the brain!!
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Arnold, Mo.
Joined Jul 2005
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Consider this:

Some of the ponds I run my boat in, the summer time temp of the water is considerably hotter at the surface. It would almost seem counter productive to water cool the electronics with hot water. If you are generating that much heat then you need to get a bigger ESC or a more efficient motor.
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