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| Author |
heat powered refrigeration
|
|
| JTurner 2005-09-29, 9:21 pm |
| Hi All,
I'm told that some RV's have refrigerators that run by propane. Are there
any relatively easy ways to harness this process for air conditioning? The
process I'm musing about would use waste heat from a genny.
| |
| Harry Chickpea 2005-09-29, 10:21 pm |
| JTurner <JimT@internetconnect.org> wrote:
>Hi All,
>
>I'm told that some RV's have refrigerators that run by propane. Are there
>any relatively easy ways to harness this process for air conditioning? The
>process I'm musing about would use waste heat from a genny.
Not really. The ammonia cycle isn't naturally suited for much more
than refrigerators and ice makers, and isn't as efficient as the freon
compression technologies. Add an auto AC compressor to your genny.
| |
| NotMe 2005-09-29, 11:21 pm |
|
"JTurner" <JimT@internetconnect.org> wrote in message
news:11jouporb6itj14@news.supernews.com...
| Hi All,
|
| I'm told that some RV's have refrigerators that run by propane. Are there
| any relatively easy ways to harness this process for air conditioning?
The
| process I'm musing about would use waste heat from a genny.
alt.ammonia.refrigeration
| |
| NotMe 2005-09-29, 11:21 pm |
|
"Harry Chickpea" <hchickpeaREMOVEME@hotmail.com> wrote in message
news:433c870c.39012464@localhost...
| JTurner <JimT@internetconnect.org> wrote:
|
| >Hi All,
| >
| >I'm told that some RV's have refrigerators that run by propane. Are
there
| >any relatively easy ways to harness this process for air conditioning?
The
| >process I'm musing about would use waste heat from a genny.
|
| Not really. The ammonia cycle isn't naturally suited for much more
| than refrigerators and ice makers, and isn't as efficient as the freon
| compression technologies. Add an auto AC compressor to your genny.
??
My mother is using a genset/absorption combination in New Orleans that was
built by my grand father in the late 40s.
You are technically correct in that absorption systems are less efficient
but the OP is proposing to use waste heat.
| |
| Harry Chickpea 2005-09-30, 12:21 am |
| "NotMe" <me@privacy.net> wrote:
>
>"Harry Chickpea" <hchickpeaREMOVEME@hotmail.com> wrote in message
>news:433c870c.39012464@localhost...
>| JTurner <JimT@internetconnect.org> wrote:
>|
>| >Hi All,
>| >
>| >I'm told that some RV's have refrigerators that run by propane. Are
>there
>| >any relatively easy ways to harness this process for air conditioning?
>The
>| >process I'm musing about would use waste heat from a genny.
>|
>| Not really. The ammonia cycle isn't naturally suited for much more
>| than refrigerators and ice makers, and isn't as efficient as the freon
>| compression technologies. Add an auto AC compressor to your genny.
>
>??
>
>My mother is using a genset/absorption combination in New Orleans that was
>built by my grand father in the late 40s.
>
>You are technically correct in that absorption systems are less efficient
>but the OP is proposing to use waste heat.
>
Care to describe that combo built by your grandfather? It sounds like
what the poster wants.
One of the main issues with homebuilt ammonia cycles is the danger of
a gas escape. Anhydrous ammonia gas damages lungs and even kills.
Calcium carbonate is much safer, but there is yet another drop in
efficiency. I'm not sure I would be comfortable with an Li system.
Also, any of these systems take a lot of space and work on a cycle
rather than continuously. Freon became popular for a reason.
Scavanging waste heat for heating is great. Turning it into useful AC
is much more difficult.
| |
| NotMe 2005-09-30, 12:21 am |
|
"Harry Chickpea"
| >| >Hi All,
| >| >
| >| >I'm told that some RV's have refrigerators that run by propane. Are
| >there any relatively easy ways to harness this process for air
conditioning?
| >The process I'm musing about would use waste heat from a genny.
| >|
| >| Not really. The ammonia cycle isn't naturally suited for much more
| >| than refrigerators and ice makers, and isn't as efficient as the freon
| >| compression technologies. Add an auto AC compressor to your genny.
| >
| >??
| >
| >My mother is using a genset/absorption combination in New Orleans that
was
| >built by my grand father in the late 40s.
| >
| >You are technically correct in that absorption systems are less efficient
| >but the OP is proposing to use waste heat.
| >
| Care to describe that combo built by your grandfather? It sounds like
| what the poster wants.
|
| One of the main issues with homebuilt ammonia cycles is the danger of
| a gas escape. Anhydrous ammonia gas damages lungs and even kills.
| Calcium carbonate is much safer, but there is yet another drop in
| efficiency. I'm not sure I would be comfortable with an Li system.
| Also, any of these systems take a lot of space and work on a cycle
| rather than continuously. Freon became popular for a reason.
|
| Scavanging waste heat for heating is great. Turning it into useful AC
| is much more difficult.
I don't recall saying anything about being a home brew project. The man
designed and maintained major Ice Houses systems in the Gulf coast area
which included NOLA for years. That said much of what he did do was the
first application of the idea. Sadly he did not patent anything. As to the
specifics of how and what he did I was far too young to make notice of
anything when it was done and did not pay proper attention to what was done
to maintain the system when I was. I'll ask those that do know but it will
be months before they're in any position to answer questions as they are far
too busy with Katrina problems.
| |
|
|
| Arnold Walker 2005-09-30, 5:21 am |
|
"NotMe" <me@privacy.net> wrote in message
news:Uo0%e.18034$L45.2210@fe07.lga...
>
> "JTurner" <JimT@internetconnect.org> wrote in message
> news:11jouporb6itj14@news.supernews.com...
> | Hi All,
> |
> | I'm told that some RV's have refrigerators that run by propane. Are
there
> | any relatively easy ways to harness this process for air conditioning?
> The
> | process I'm musing about would use waste heat from a genny.
>
> alt.ammonia.refrigeration
>
>
It might be added that kalina cycle on geothermo and diesel combined
steamplants use ammonia.
Usually about 30% concentation.
Some of what they do on varying the concentation in different parts of the
system may improve on
ammonia refrigeration in terms of a continuous cycle.
30% boils at about 143F. instead of 212F. like straight water.
Still studying tables ,etc for a diesel combined steamplant for a vehicle.
Ammonia like alcohol depends on the water % as far as flamable goes.
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http://www.droptable.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
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| |
|
| > One of the main issues with homebuilt ammonia cycles is the danger of
> a gas escape. Anhydrous ammonia gas damages lungs and even kills.
> Calcium carbonate is much safer, but there is yet another drop in
> efficiency. I'm not sure I would be comfortable with an Li system.
Ammonia absorbtion refrigeration uses ammonia as the refrigerant and water
as the absorber. Lithium bromide cooling systems use lithium bromide salts
as the absorbent and water as the refrigerant. I've never heard of calcium
carbonate used for an absorbtion type cooler.
Lithium Bromide absorbtion coolers work well for air conditioning and can
be powered with waste heat, but they cannot reach the below freezing
temperatures possible with ammonia absorbtion refrigeration.
> Also, any of these systems take a lot of space and work on a cycle
> rather than continuously. Freon became popular for a reason.
Absorbtion refrigeration can be done in a two stage process (regenerating
then cooling), but some ammonia absorbtion systems are designed to operate
in a continuous cycle.
> Scavanging waste heat for heating is great. Turning it into useful AC
> is much more difficult.
That depends on how hot the waste heat is and how much waste heat is
available. The thermodynamic efficiency may be small, but if we can use the
heat that would be otherwise wasted, we should.
CM
| |
| JTurner 2005-09-30, 10:21 am |
| Harry Chickpea wrote:
>
> One of the main issues with homebuilt ammonia cycles is the danger of
> a gas escape. Anhydrous ammonia gas damages lungs and even kills.
Hmmm. We have an old, old refrigerator in the barn (wood interior with
porcelain exterior) - I'm told it is ammonia powered even tho it's
electricity.
Is ammonia heavier than air or lighter than air?
| |
| Harry Chickpea 2005-09-30, 12:21 pm |
| "CM" <cm@cm.not.really> wrote:
>
>Ammonia absorbtion refrigeration uses ammonia as the refrigerant and water
>as the absorber. Lithium bromide cooling systems use lithium bromide salts
>as the absorbent and water as the refrigerant. I've never heard of calcium
>carbonate used for an absorbtion type cooler.
California researchers have attempted using the dessecant capabilities
of CaCl to take hot moist air, dry it (increasing the heat in the
process) cooling it in an enclosed area, spraying moisture back into
the cooled dry air to cool it further. The process needs more
refinement, but it does lend itself to waste or solar heat to dry out
the dissecant. I've fooled around with CaCl. While it is absorbing
moisture via a pad with CaCl embedded, it can increase the air temp of
breath to close to 150 degrees F. That obviously reduces the ease
with which it cools, but proper staging could overcome that.
>Lithium Bromide absorbtion coolers work well for air conditioning and can
>be powered with waste heat, but they cannot reach the below freezing
>temperatures possible with ammonia absorbtion refrigeration.
RIght. Also, LiBr is a lot more dangerous to have around than CaCl.
>
>Absorbtion refrigeration can be done in a two stage process (regenerating
>then cooling), but some ammonia absorbtion systems are designed to operate
>in a continuous cycle.
I knew as soon as I hit the send button that I had mis-spoken. You
are correct, of course.
>
>That depends on how hot the waste heat is and how much waste heat is
>available. The thermodynamic efficiency may be small, but if we can use the
>heat that would be otherwise wasted, we should.
Maybe. Sometimes the cost of construction and maintenance, and
potential problems outweigh the benefits. Most of us here would at
least know how to handle basic problems, but what happens if we go on
vacation or are incapacitated for a few months? What happens if a kid
cracks a valve or a hurricane or speeding car breaks open an anhydrous
ammonia system? What happens when the system has to be
decommissioned?
| |
| Harry Chickpea 2005-09-30, 1:21 pm |
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"NotMe" <me@privacy.net> wrote:
>I don't recall saying anything about being a home brew project. The man
>designed and maintained major Ice Houses systems in the Gulf coast area
>which included NOLA for years. That said much of what he did do was the
>first application of the idea. Sadly he did not patent anything. As to the
>specifics of how and what he did I was far too young to make notice of
>anything when it was done and did not pay proper attention to what was done
>to maintain the system when I was. I'll ask those that do know but it will
>be months before they're in any position to answer questions as they are far
>too busy with Katrina problems.
>
The original poster was musing on how he could take advantage of waste
heat from a genny, so the implication of "home brew" was there. I'm
impressed with your grandfather's ingenuity and his credentials. That
doesn't change the fact that his was a (very skilled) homebrew project
outside of any certified safety testing, governmental regulation,
etc.. If he had brought the project to market and made more than the
prototype, then it would be out of that category. Home brew doesn't
automatically mean slipshod or dangerous, and I'd have loved to seen
this system.
Sometimes great ideas get lost in history. For me, one of the
fantastic powers of the internet is its ability to bring some of these
ideas back out of obscurity.
| |
| Harry Chickpea 2005-09-30, 1:21 pm |
| JTurner <JimT@internetconnect.org> wrote:
>Is ammonia heavier than air or lighter than air?
Open a bottle of household ammonia and you'll find it doesn't really
matter. Permeating is the operative word.
| |
| Dale Farmer 2005-09-30, 3:21 pm |
|
Harry Chickpea wrote:
> "CM" <cm@cm.not.really> wrote:
>
>
> California researchers have attempted using the dessecant capabilities
> of CaCl to take hot moist air, dry it (increasing the heat in the
> process) cooling it in an enclosed area, spraying moisture back into
> the cooled dry air to cool it further. The process needs more
> refinement, but it does lend itself to waste or solar heat to dry out
> the dissecant. I've fooled around with CaCl. While it is absorbing
> moisture via a pad with CaCl embedded, it can increase the air temp of
> breath to close to 150 degrees F. That obviously reduces the ease
> with which it cools, but proper staging could overcome that.
>
>
> RIght. Also, LiBr is a lot more dangerous to have around than CaCl.
>
>
> I knew as soon as I hit the send button that I had mis-spoken. You
> are correct, of course.
>
>
> Maybe. Sometimes the cost of construction and maintenance, and
> potential problems outweigh the benefits. Most of us here would at
> least know how to handle basic problems, but what happens if we go on
> vacation or are incapacitated for a few months? What happens if a kid
> cracks a valve or a hurricane or speeding car breaks open an anhydrous
> ammonia system? What happens when the system has to be
> decommissioned?
Ammonia is easy. You dissolve it in water and sprinkle it on your roses.
If there is a failure that lets it leak out, most folks can easily smell
dangerous
concentrations and leave the area. I would think that the quantity used in
a home cooling system would not be large enough to require a hazard plan.
Biggest problem with the ammonia fridgerators that are commonly used
in motor homes and trailers are operating out of level, which destroys the
ammonia loop. ( the whys and wherefores should be findable on RV
hobbyist sites)
Building a passive ammonia loop that uses waste heat is a task for an
advanced hobbyist. You have to make a system that can contain hydrogen
gas at a couple of hundred psi, and all the liquid return piping slope back
correctly. Some of the other chemicals in the loop that make the cycle
run more efficiently are quite toxic.
That being said, you could use some of the prepackaged ammonia
loops that are made for RV fridges, and use a few of these to cool
a more hobbyist friendly heat transfer medium, such as water.
--Dale
| |
| daestrom 2005-09-30, 8:21 pm |
|
"Harry Chickpea" <hchickpeaREMOVEME@hotmail.com> wrote in message
news:433d5223.3047600@localhost...
> "CM" <cm@cm.not.really> wrote:
>
>
> California researchers have attempted using the dessecant capabilities
> of CaCl to take hot moist air, dry it (increasing the heat in the
> process) cooling it in an enclosed area, spraying moisture back into
> the cooled dry air to cool it further. The process needs more
> refinement, but it does lend itself to waste or solar heat to dry out
> the dissecant. I've fooled around with CaCl. While it is absorbing
> moisture via a pad with CaCl embedded, it can increase the air temp of
> breath to close to 150 degrees F. That obviously reduces the ease
> with which it cools, but proper staging could overcome that.
>
>
> RIght. Also, LiBr is a lot more dangerous to have around than CaCl.
>
Don't know about that. We used LiBr on submarines. The salt doesn't give
off any hazardous vapors, and is easy to handle with no/little precautions.
The only problem we had is if the concentration gets to high and you lose
heating steam, it would solidify in the piping (i.e. 'rock up') and was a
devil to fix.
The only major problem with LiBr systems were maintaining the extremely high
vacumn needed to have the water refrigerent 'boil' at around 35-38F. And
the occasional injection of a bottle of alcohol to reduce the water's
surface tension.
We had a unit rated for 160 tons A/C and could reliably get > 200 tons
cooling as measured by flow-rate and delta-T.
daestrom
| |
|
|
"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in message
news:dxj%e.7989$K91.4250@twister.nyroc.rr.com...
> Don't know about that. We used LiBr on submarines. The salt doesn't give
> off any hazardous vapors, and is easy to handle with no/little
> precautions. The only problem we had is if the concentration gets to high
> and you lose heating steam, it would solidify in the piping (i.e. 'rock
> up') and was a devil to fix.
>
> The only major problem with LiBr systems were maintaining the extremely
> high vacumn needed to have the water refrigerent 'boil' at around 35-38F.
> And the occasional injection of a bottle of alcohol to reduce the water's
> surface tension.
>
> We had a unit rated for 160 tons A/C and could reliably get > 200 tons
> cooling as measured by flow-rate and delta-T.
>
> daestrom
LiBr systems are usually large and heavy, even the domestic direct fired
ones I have seen weigh tons.
Here is some info on them for anyone who wants it, but first let me say that
some special expertise is needed to operate one of these, except for the
smaller domestic ones, and even then they use huge amounts of heat to obtain
a reasonable amount of cooling, and these systems have been designed and
built by experts, and they still can have problems.
Anyway here is a bit about them :-
All absorption chillers use electric power to operate these pumps, the
condenser water pumps and cooling tower fans. They also use more water as
they must reject more heat and require larger cooling towers.
Absorption chillers are more difficult than electric chillers to put on-line
(start up) and to take off-line (shut down) as they require a dilution
cycle. All of these issues should be addressed in discussions with
manufacturers, designers and mechanical contractors.
Waste Heat Fired Absorption Chillers
Most absorption chillers use either steam or fuel (natural gas, propane) for
heat input. But, waste heat from process, reciprocating engine, gas turbine,
or a cogeneration system can also be used in the absorption process. The
exhaust should have a minimum temperature of about 550 F and a maximum of
1,500 F. The most common application is using the exhaust from a gas turbine
to provide cooling for the intake air or other cooling requirements. The
available cooling is a function of the exhaust gas temperature and mass flow
rate, using this
http://www.southernco.com/gapower/e...=com&mnuItem=ed
===================
A little more on these systems
http://www.dbdh.dk/pdf/cooling-pdf/DC-in-Copenhagen.pdf
Once when playing around with design work, I figured you needed twice the
heat input compared to cooling output.
====================
As for ammonia, well anyone who has been anywhere near an ammonia system
when it has sprung a leak, will tell you just how bad it is, it can kill,
explode or burn, not nice stuff to be around, and it only takes a little to
get loose to make it very nasty.
It turns to a strong extremely alkaline when it get to moisture so when it
hits the eyes or lungs you really know all about it, I know, been there done
that.
In a ammonia system plant room they have emergency breathing gear, and there
is a very good reason for that.
It is NOT the stuff anyone would want in an air conditioning system, unless
you have a death wish to die rather nastily.
Further to that you cannot use copper in an ammonia system, so it is usually
steel pipe work and that makes it a very heavy system.
| |
| daestrom 2005-10-01, 9:21 pm |
|
<RamRod Sword of Baal> wrote in message news:433ec7ce$1@quokka.wn.com.au...
>
> "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in message
> news:dxj%e.7989$K91.4250@twister.nyroc.rr.com...
>
>
>
>
> LiBr systems are usually large and heavy, even the domestic direct fired
> ones I have seen weigh tons.
>
> Here is some info on them for anyone who wants it, but first let me say
> that some special expertise is needed to operate one of these, except for
> the smaller domestic ones, and even then they use huge amounts of heat to
> obtain a reasonable amount of cooling, and these systems have been
> designed and built by experts, and they still can have problems.
>
>
Yes, that's true too. On nuc submarines, steam is 'cheap'. We used LiBr
because they were *quiet*. Only a half dozen circulating pumps (let's see
IIRC, there was 'generator', 'refrigerent', 'absorber', 'purge', 'seawater',
and 'chilled-water' ;-). And centrifugal pumps can be vibration isolated
and run pretty quite. Reciprocating R-12 compressors are *noisy*. I
understand that newer boats used scroll-compressor units with R-114.
daetrom
| |
| NotMe 2005-10-02, 10:21 pm |
| "Harry Chickpea"
| >
| The original poster was musing on how he could take advantage of waste
| heat from a genny, so the implication of "home brew" was there. I'm
| impressed with your grandfather's ingenuity and his credentials. That
| doesn't change the fact that his was a (very skilled) homebrew project
| outside of any certified safety testing, governmental regulation,
| etc.. If he had brought the project to market and made more than the
| prototype, then it would be out of that category. Home brew doesn't
| automatically mean slipshod or dangerous, and I'd have loved to seen
| this system.
|
| Sometimes great ideas get lost in history. For me, one of the
| fantastic powers of the internet is its ability to bring some of these
| ideas back out of obscurity.
Recall this was pre 1940's and there were not many formal regulations much
less testing/certification labs. I doubt seriously if any of the
information made it to the internet in any identifiable form.
| |
| John A. 2005-10-07, 2:21 pm |
| On Fri, 30 Sep 2005 15:19:18 GMT, hchickpeaREMOVEME@hotmail.com (Harry
Chickpea) wrote:
>"NotMe" <me@privacy.net> wrote:
>
>The original poster was musing on how he could take advantage of waste
>heat from a genny, so the implication of "home brew" was there. I'm
>impressed with your grandfather's ingenuity and his credentials. That
>doesn't change the fact that his was a (very skilled) homebrew project
>outside of any certified safety testing, governmental regulation,
>etc.. If he had brought the project to market and made more than the
>prototype, then it would be out of that category. Home brew doesn't
>automatically mean slipshod or dangerous, and I'd have loved to seen
>this system.
>
>Sometimes great ideas get lost in history. For me, one of the
>fantastic powers of the internet is its ability to bring some of these
>ideas back out of obscurity.
What is a GENNY ?
Please. Don't send me to Google. Out of many sites, nothing makes
sense to me.
| |
|
|
|
|
|