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'[OT]Solar Ice Maker'
2007\08\02@202744 by jtroxas

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Is it posible to use Acetone in place of pure Ammonia which is toxic as
refrigerant in one of those Solar Icemaker(file attched).. Or is the boiling
point of
acetone just too high... both has almost equal heat of vaporization..

Ammonia Adsorption Solar Icemaker
http://www.aidg.net/index.php?option=com_remository&Itemid=34&func=download&filecatid=2



2007\08\03@111838 by Bob Axtell

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jtroxas wrote:
> Is it posible to use Acetone in place of pure Ammonia which is toxic as
> refrigerant in one of those Solar Icemaker(file attched).. Or is the boiling
> point of
> acetone just too high... both has almost equal heat of vaporization..
>
> Ammonia Adsorption Solar Icemaker
> http://www.aidg.net/index.php?option=com_remository&Itemid=34&func=download&filecatid=2
>
>
>
>  
The difference is more to do with the ability of ammonia to compress
easily rather than its heat of vaporation. Acetone doesn't compress
easily (if at all). Also, ammonia is preferred as a refrigerant (while
being toxic) because it won't damage the ozone layer like freon does.

I am not sure that the method shown in the article is very efficient.

I have seen a "closed loop" refrigerator similar to this in rural
Nicaragua. Here's what I remember about that one: the owner placed it
outside in the sun until the  ammonia was fully compressed (heat from
the sun caused the ammonia to be forced into liquid form into a pool by
a one-way valve). When it was then put into the "icebox" and a valve
released, it made ice all night long as the ammonia evaporated. Except
for the fuss of dealing with the "cooling equipment", it worked as good
as any modern refrigerator. I remember it as being made of glass and
tubes, but it might have been stainless steel here and there.

I have a client who is incredibly interested in solar products. He is
presently experimenting with "swamp" (water evaporative) coolers. He has
reduced the temperature of my office from 110F to 75F by use of a
proprietary means of forcing the evaporation of water by breaking the
water into a fine mist.

This "swamp cooler" and the Nicaraguan refrigerator work in a similar way.

--Bob Axtell

2007\08\03@114049 by Spehro Pefhany

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face
Quoting Bob Axtell <spam_OUTengineerTakeThisOuTspamcotse.net>:


> I have a client who is incredibly interested in solar products. He is
> presently experimenting with "swamp" (water evaporative) coolers. He has
> reduced the temperature of my office from 110F to 75F by use of a
> proprietary means of forcing the evaporation of water by breaking the
> water into a fine mist.
>
> This "swamp cooler" and the Nicaraguan refrigerator work in a similar way.
>
> --Bob Axtell

The "swamp coolers" are usable in places with very low RH such as Arizona,
but not too useful elsewhere. A friend in Phoenix has a cooling system
outside on his deck. Very high pressure water (800-1000 PSI or something like
that) is forced through nozzles so it can be atomized into very fine
particles, which very quickly evaporate. It lowers the
temperature on the deck by 20'F almost instantly, with very little energy
consumption. I've also seem them used in Tucson for house A/C.

The Nicaraguan fridge is interesting. It obviously stores a fair amount of
energy in the phase change.

Best regards,
Spehro Pefhany






2007\08\03@114136 by Michael Rigby-Jones

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>-----Original Message-----
>From: .....piclist-bouncesKILLspamspam@spam@mit.edu [piclist-bouncesspamKILLspammit.edu]
>On Behalf Of Bob Axtell
>Sent: 03 August 2007 16:18
>To: Microcontroller discussion list - Public.
>Subject: Re: [OT]Solar Ice Maker
>
>
>I have a client who is incredibly interested in solar products. He is
>presently experimenting with "swamp" (water evaporative)
>coolers. He has
>reduced the temperature of my office from 110F to 75F by use of a
>proprietary means of forcing the evaporation of water by breaking the
>water into a fine mist.
>
>This "swamp cooler" and the Nicaraguan refrigerator work in a
>similar way.

"Overclockers" have been using home brewed water based evaporators (known as "bongs"!) to cool their tortured CPUs for quite a long time.

The danger with air conditioning using water are the nasties such as legionaires.

Regards

Mike

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2007\08\03@122130 by Goflo

picon face

---- Bob Axtell <.....engineerKILLspamspam.....cotse.net> wrote:
> I have seen a "closed loop" refrigerator similar to this in rural
> Nicaragua. Here's what I remember about that one: the owner placed it
> outside in the sun until the  ammonia was fully compressed (heat from
> the sun caused the ammonia to be forced into liquid form into a pool by
> a one-way valve). When it was then put into the "icebox" and a valve
> released, it made ice all night long as the ammonia evaporated.

NH3/H2O intermittent absorption cycle works well. Such refrigerators,
powered by kerosene, were commercially available before WW2. One
can imagine a solar powered version...

www.ggw.org/~cac/IcyBall/HomeBuilt/HallPlans/IB_Directions.html

2007\08\03@125345 by James Newtons Massmind

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{Quote hidden}

Have you seen our heard of Zeolite adsorption (not misspelled) cooling?

http://techref.massmind.org/techref/other/zeolitefridg.htm

Check the links at the bottom of the page.

---
James Newton, massmind.org Knowledge Archiver
EraseMEjamesspam_OUTspamTakeThisOuTmassmind.org 1-619-652-0593 fax:1-208-279-8767
http://www.massmind.org Saving what YOU know.

2007\08\03@131946 by Cedric Chang

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face
{Quote hidden}

The ammonia approach does not add humidity to the air while the
swamp cooler increases humidity and works poorly when humidity
is already high.
http://en.wikipedia.org/wiki/Evaporative_cooler <---- see second  
paragraph
Cedric
{Quote hidden}

> --

2007\08\03@164635 by Bob Axtell

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James Newtons Massmind wrote:
{Quote hidden}

A great link, James. Thanks.

2007\08\03@165344 by jtroxas

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What is Zeolite??...
Is Zeolite those white crystals people put in their underarms to cure
underarm body odor...

Also since the working fluid is water which freezes from top to bottom....
wont the frozen ice on the top prevent further vaporization... so that only
some percent of the water is vaporized.. preventing further cooling..

"James Newtons Massmind" <KILLspamjamesnewtonKILLspamspammassmind.org> wrote in message
news:02ce01c7d5ee$d6f3e7b0$1100a8c0@SONYGRT270PB...
{Quote hidden}

> --

2007\08\03@175641 by James Newtons Massmind

face picon face
> > Have you seen our heard of Zeolite adsorption (not
> misspelled) cooling?
> >
> > techref.massmind.org/techref/other/zeolitefridg.htm
> >
>
> What is Zeolite??...

http://en.wikipedia.org/wiki/Zeolite Zeolites (Greek, zein, "to boil";
lithos, "a stone") are minerals that have a micro-porous structure

> Is Zeolite those white crystals people put in their underarms
> to cure underarm body odor...

Not where I come from, but I suppose it would work...

> Also since the working fluid is water which freezes from top
> to bottom....
> wont the frozen ice on the top prevent further
> vaporization... so that only some percent of the water is
> vaporized.. preventing further cooling..

The ice will melt as the container absorbs heat from the freezer box,
restarting the evaporation as needed. It may be that a level, shallow
container would work better than a narrow, tall one.

---
James Newton, massmind.org Knowledge Archiver
spamBeGonejamesspamBeGonespammassmind.org 1-619-652-0593 fax:1-208-279-8767
http://www.massmind.org Saving what YOU know.

2007\08\03@180231 by Goflo

picon face

> Also since the working fluid is water which freezes from top to bottom....
> wont the frozen ice on the top prevent further vaporization... so that only
> some percent of the water is vaporized.. preventing further cooling..

No, the ice will absorb heat, (~970 btu/lb), melt, and boil off, or sublime
if the pressure is low enough. It's the pressure I'm dubious about - I'm
recovering from a move right now and can't lay hands on the data, but
am guessing you need a pressure of  <.01 psi or so for the system to
behave as described. Not exactly a hard vacuum, of course, but could
be a challenge for a hand-pumped PVC pipe rig... I'd like to try it.

2007\08\03@181419 by Goflo

picon face
I fudged the numbers - Solid to liquid phase absorbs 144 btu/lb.
Liquid to vapor phase absorbs 970 btu/lb. Cycling 2 lbs of water
a day  in a well insulated box would make a pretty good cooler.
Interesting stuff!

Jack

---- TakeThisOuTgofloEraseMEspamspam_OUTcox.net wrote:
> No, the ice will absorb heat, (~970 btu/lb), melt, and boil off, or sublime
> if the pressure is low enough. It's the pressure I'm dubious about - I'm
> recovering from a move right now and can't lay hands on the data, but
> am guessing you need a pressure of  <.01 psi or so for the system to
> behave as described. Not exactly a hard vacuum, of course, but could
> be a challenge for a hand-pumped PVC pipe rig... I'd like to try it.

2007\08\03@182712 by Alex Harford

face picon face
On 8/3/07, RemoveMEgoflospamTakeThisOuTcox.net <gofloEraseMEspam.....cox.net> wrote:
>
> > Also since the working fluid is water which freezes from top to bottom....
> > wont the frozen ice on the top prevent further vaporization... so that only
> > some percent of the water is vaporized.. preventing further cooling..
>
> No, the ice will absorb heat, (~970 btu/lb), melt, and boil off, or sublime
> if the pressure is low enough. It's the pressure I'm dubious about - I'm
> recovering from a move right now and can't lay hands on the data, but
> am guessing you need a pressure of  <.01 psi or so for the system to
> behave as described. Not exactly a hard vacuum, of course, but could
> be a challenge for a hand-pumped PVC pipe rig... I'd like to try it.

I came to the same conclusion.  Search for Crosley IcyBall in the archives:

=========================================================
On 10/7/06, James Newtons Massmind <EraseMEjamesnewtonspammassmind.org> wrote:
> > > techref.massmind.org/techref/other/zeolitefridg.htm
> >
> > That one is very interesting.  A couple of  questions:
> >
> > - what is the purpose of the heat exchanger?  Could the water
> > freeze in there and cause maintenance problems?
>
> To cool the refrige box. If the water freezes, it will only stop operation
> long enough for the ice to melt.

I thought that the water evaporating in the box did the cooling?

> > - how much vacuum is required?  I'm thinking an electric
> > vacuum pump made for hot rods might be useful.  They
> > generally turn on at < 15 psi and pump until 25 psi is reached.
>
> The purpose of the vacuum is to make the water boil at a lower temperature.
> So the amount of vacuum needed is enough to make the water boil at the
> temperature you want the refrige to maintain.

Looking at this link:

http://www.chemistrycoach.com/vapor_pressure_of_water.htm

if you wanted to get down to -10*C, you would need a pressure of
2.1mmHg.  Even at 0*C, you need 4.6mmHg (0.08895psi), which is a very
low pressure.  Am I looking at the right chart?

BTW this site does nice conversions:
http://www.convert-me.com/en/convert/pressure

2007\08\03@190056 by jtroxas

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Which kind/form of Zeolite is used here??..

"James Newtons Massmind" <RemoveMEjamesnewtonEraseMEspamEraseMEmassmind.org> wrote in message
news:038b01c7d619$279f3460$1100a8c0@SONYGRT270PB...
{Quote hidden}

> --

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