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Vance,
Air is the least effective means to cool something
that is enclosed. The problem with air, if it is exchanged in a fast enough
rate, it works great. On the other hand....if you can't exchange the air, you
end up with an oven. Oil on the other hand can carry more heat
away faster. The density is the factor here. Air is not very dense, so it will
only absorb so much thermal energy per unit.Oil will absorb many more btu per
unit than air. Also because oil will thermocycle.....the oil will transfer the
heat to the container that contains it faster.
I think an air filled thruster would work good too,
but there are problems with compression. If there are any bearings housed within
the casing......they will bind under extreme pressure if filled with air. An oil
filled enclosure will not compress as far. There will still be compression
problems, but not to the extent of an air filled unit.
There was a project a few years ago....a guy made a
gaming computer that used oil to keep all the expensive parts cool. You should
look it up. It worked really well. (Oil cooled computer)
I do not plan at this point to run a reduction
gear. BLDC motors are real good at direct drive.
I would like to build smaller thrusters that can go
very deep.
James Long
Owner/Designer
Lil Brother LLC (Instrument Division)
----- Original Message -----
Sent: Sunday, July 29, 2007 8:55 AM
Subject: Re: [PSUBS-MAILIST] Diver
Lockout.... serious question here!!
James,
Serious DLOs have dive chambers separate from the crew compartment. And
as for your thrusters, in my experience AIR transmits heat faster than oil.
How deep are you building these things for? HBOI, for instance, runs aluminum
cans and PM motors in air to 3000 feet, with no real problems. The commercial
units that Nuytco uses ARE oil filled, I believe, but have a higher pressure
rating, and no reduction gear.
Vance
-----Original Message-----
From: Lil Brother LLC
<lil_brother_llc@bellsouth.net>
To:
personal_submersibles@psubs.org
Sent: Sun, 29 Jul 2007 12:29 am
Subject:
[PSUBS-MAILIST] Diver Lockout.... serious question here!!
I've got into some pretty serious questions lately......and I've done a
little reading about diver lockout (archives), but the archives raised a
question.
If you have a 1 atm sub, with a diver lockout........how do you lock a diver
back in?
Are there any 1 atm subs with a lockout?
If there are......if the lockout has been pressurized to the outside
pressure........what method is used to depressurize it back to 1 atm?
(these questions are redundant I know)
And the last....the important one.....is this on the dangerous side? If you
depressurize to fast......the bends.
I was reading about the nice sub.....(the Krata I think.....please don't
quote me ....I've had a very long two days)......but I didn't notice if it
was 1 atm or not.
Some one learn me on this. :-)
(Hey....at least I know what a VBT is for now.)
James Long
Owner/Designer
Lil Brother LLC (Instrument Division)
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