Brian Whatcott wrote:

On Sat, 22 Sep 2007 01:21:39 +0000, Larry wrote:

[Brian]

The boiling point of water at the top of a sealed 40 ft column of
water is near ambient.


My deepest apologies to the engineers who may be rolling under their
desks, crushing their pocket protectors. It took me a while to stop
chortling. I nearly lost my Chinese dinner!

..

Larry


They say if you give a fool half a chance, he will rush in.
And so he did. TWICE! Chortling, at that.

Brian W


And your point was???

On Sat, 22 Sep 2007 01:04:55 -0500, cavelamb himself
wrote:

Brian Whatcott wrote:

The boiling point of water at the top of a sealed 40 ft column of
water is near ambient.

They say if you give a fool half a chance, he will rush in.
And so he did. TWICE! Chortling, at that.

Brian W

And your point was???

Put this pointy hat on, and go stand in the corner
with that other fellow.
I'll tell you when to sit down again.

Brian W

"N:dlzc D:aol T:com (dlzc)" wrote:

Dear Larry:

"Larry" wrote in message
...
dlzc wrote in news:1190415672.506271.93890
@k79g2000hse.googlegroups.com:

There are ship-board distiller units that use an
engine to pull a vacuum, and the engine's
waste heat to boil that water, to generate
drinking water. A little shorter...

http://en.wikipedia.org/wiki/Boiling_point

"The boiling point of water is 100 0C (212 0F) at
standard pressure. On top of Mount Everest the
pressure is about 260 mbar (26 kPa) so the
boiling point of water is 69 0C. (156.2 0F)."

AT 40' ASL, the boiling point must be down
to...to....211.95F!

What Brian left to the reader's imagination, is that the head
space of the tubes is at a near perfect vacuum, flooded only with
water vapor. You might recall that a perfect vacuum will lift a
column of water about 32 feet, on a high pressure day. Or had
you not figured that out?

Well no, he obviously hadn't figured that out. Nor can anybody figure
out what is going to hold a column of water 40 ft high as was stated in
the original post. The tubes may be 40 feet but the column of water will
be considerably less. How much less will depend on how much energy is
heating on the hot side and how much energy is cooling on the cool side.
The total amount of energy needed is not going to be any different than
any other distilling method.
Unless you have the free or cheap sources of cooling and heating at
specific temperatures this isn't going to work any better either.

-jim




David A. Smith

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On Sat, 22 Sep 2007 10:15:40 -0500, jim wrote:


What Brian left to the reader's imagination, is that the head
space of the tubes is at a near perfect vacuum, flooded only with
water vapor. You might recall that a perfect vacuum will lift a
column of water about 32 feet, on a high pressure day. Or had
you not figured that out?

Well no, he obviously hadn't figured that out. Nor can anybody figure
out what is going to hold a column of water 40 ft high as was stated in
the original post. The tubes may be 40 feet but the column of water will
be considerably less. How much less will depend on how much energy is
heating on the hot side and how much energy is cooling on the cool side.
The total amount of energy needed is not going to be any different than
any other distilling method.
Unless you have the free or cheap sources of cooling and heating at
specific temperatures this isn't going to work any better either.

-jim



Well, at least this respondent Jim, is operating at shall we say the
7th grade level of science/engineering insight. Like so many other
products of the domestic school system, he seems to have a severe
case of self-esteem syndrome.

Still, he may be retrievable, starting with a science demonstration
he may have missed. Place a beaker of water in a bell-jar and pump
the air out.

When 99% of the air has been pumped out, the water in the beaker is
boiling vigorously, until, in the usual way, the beaker boils dry.
The beaker feels cool to the touch, naturally.

To quote him: "unless I have a cheap source of heating this won't
work..."

For the $64 prize: NOW do you get it?

Brian Whatcott Altus OK

Sounds neat, haven't seen that one before.
Thanks for sharing.


"Roger Long" wrote in message
...
There's another neat way you can demonstrate this with minimal equipment.

Take a tight fitting jar and get the water boiling vigerously in it with
the cap on loose enough to let the steam out. When it is full of dense
steam and about 1/3 boiling water, remove instantly from heat and tighten
cap.

When everything is cooled to room temperature, put an ice cube against the
jar and the water will start to boil. The ice condenses the water vapor
further, reducing the pressure to the point where the water will boil at
room temperature.

I've seen it done and it looks like the ice cube is boiling the water.

My father won a science fair doing this back in the 1930's.

--
Roger Long

On Fri, 21 Sep 2007 17:35:02 -0500, Brian Whatcott
wrote:

The boiling point of water at the top of a sealed 40 ft column of
water is near ambient.
So, it doesn't take much heat to boil the brackish water, and have it
pass to the fresh column where it is slightly cooled to hold the near
vacuum conditions at the boiling level.

Fraid not. It takes the same ammount of heat to boil water as at 212F.
Approximately 1175 BTU/lb. You might save a little not heating the
water all the wqy to 212.

"Brian Whatcott" wrote in message
...

You've heard all about distilling water, and you've heard all about
reverse osmosis, but you haven't heard about low-cost, low energy
stills: they are brand new.

Briefly:
Take one forty ft vertical tube filled with saline.
Take one forty ft vertical tube filled with fresh water.
Connect them with a little engineering help - at the top.

The boiling point of water at sea level pressure is about 100 deg C

The boiling point of water at the top of a sealed 40 ft column of
water is near ambient.
So, it doesn't take much heat to boil the brackish water, and have it
pass to the fresh column where it is slightly cooled to hold the near
vacuum conditions at the boiling level.

[An engineering effort of a U of Utah group I think]

Brian Whatcott Altus OK


Lame suggestion and unworkable on most boats. Ya gotta think outta the
box, man.

However, there is another way. I thought it up all by my lonesome. All
you need is a reverse osmosis membrane. You put it into a chamber that
is vented to atmosphere on the inside and to the ocean on the outside of
the membrane. You lower it into the ocean to a depth of only 500 feet
and the pressure of the water is enough to push fresh water through the
membrane into the chamber. When it gets full you haul it up and empty in
into your tanks. Reverse osmosis without any energy used to get it.
Ain't Wilbur brilliant?

Wilbur Hubbard

"N:dlzc D:aol T:com \(dlzc\)" wrote in newsv_Ii.42363$L_
:

What Brian left to the reader's imagination, is that the head
space of the tubes is at a near perfect vacuum, flooded only with
water vapor. You might recall that a perfect vacuum will lift a
column of water about 32 feet, on a high pressure day. Or had
you not figured that out?

David A. Smith


There's a limit to the vacuum boiling. After a certain point, water goes
from a solid straight to a gas with no liquid state, just like CO2 does at
atmospheric pressure.

You can't pull a full vacuum on it and get liquid water.
http://invsee.asu.edu/ed/phase/phasefeat.htm
(see graph this website, point t.p.)


Larry
--
Search youtube for "Depleted Uranium"
The ultimate dirty bomb......

"Roger Long" wrote in news:46f53eef$0$5006
:

My father won a science fair doing this back in the 1930's.

--
Roger Long


Was his real name Don Herbert and he worked for GE?...

Larry
--
I don't think I ever missed a Mr Wizard TV show. Of course, if you put the
same shows on, today, Mr Wizard would be so far over the heads of the kids
with less than Master's Degrees.....they couldn't follow along...(c;

Dear Wilbur Hubbard:

"Wilbur Hubbard" wrote in
message
anews.com...
....
Lame suggestion and unworkable on most boats. Ya
gotta think outta the box, man.

However, there is another way. I thought it up all by
my lonesome. All you need is a reverse osmosis
membrane. You put it into a chamber that is vented
to atmosphere on the inside and to the ocean on the
outside of the membrane. You lower it into the
ocean to a depth of only 500 feet and the pressure
of the water is enough to push fresh water through the membrane
into the chamber. When it gets full you
haul it up and empty in into your tanks. Reverse
osmosis without any energy used to get it. Ain't Wilbur
brilliant?

You are still displacing that much water... not a small feat.

David A. Smith