wrote re air conditioning with a

Tap water heat exchanger
- No wall mount required
- No electricity used
- Will it provide enough cooling?

You _might_ cover the ceiling with lots of cold water pipes :-) Warming
1000 pounds of water per hour (about 2 gpm) 10 F would provide 10K
Btu/h of cooling. If the air-water temp diff is 10 F, with a 1.5
Btu/h-F-ft^2 slow-moving airfilm conductance, you'd need about
10K/(10x1.5) = 667 ft^2 of pipe, eg 67 4"x10' pipes, but that might not
dehumidify well, even if some condensation occurs, and it would waste a
lot of water.

If you really wanted to do this, you might make a tank around the hot
fins of a cheap window AC and fill it with oil (to avoid corrosion) and
pump lots of 110 F oil through a heat exchanger to warm 0.4 gpm of 60 F
water to about 110 F. Z = 0 and E = 1-e^(-NTU) = 0.9 makes NTU = 2.3 =
60A/200, so A = 6.7 ft^2, eg a 3"x10' copper pipe inside a 4"x10' PVC
pipe. You might pump the still-pressurized hot water back into the hot
water pipe in your apartment, where it might eventually push some cold
water out of the bottom of the water heater for the apartment building.


Nick

Cover you ceiling with pipes how pretty, and it will drip water
everywhere .

Moved to a different forum. Thanks to Nick and Stretch for the replies.

Hmm, I didn't actually move that post to this forum; maybe it was moved
here by a moderator of another forum (sci.engr.hvac or alt.hvac).

I wasn't actually considering using all that piping; Nick was merely
trying to show me that I would need an enormous radiator to make an
effective water-based cooling system.

Since I'm here, I might as well post the original message. It follows:

I live in an apartment building which does not have a provision for a
regular window air conditioner. I do have a portable 10,000 BTU unit,
but it performs very poorly and it is expensive to run. I have a porch,
and I want to put a split-system air conditioner on it.

I am an electrical engineer, and I would like to convert an existing
non-split unit rather than purchasing a split air conditioner. Even if
it doesn't save me money, I am set on trying to do it. I'm sure a lot
of people will say that it's not worth it, but if nothing else, I will
come out learning a lot about how air conditioning systems work.

My question is about the fluid which circulates between the compressor
and the indoor (air-liquid) heat exchanger. What are the advantages and
disadvantages of the following:


- Running the refrigerant from the outdoor compressor all the way to
the indoor heat exchanger
- Having two closed loops: one localized loop for the refridgerant,
which stays outside. then a second loop which is cooled by the 1st
loop, and then goes inside to the heat exchanger.

And if I do the 2nd option, what would be a good liquid to use in the
tubing? Theoretically almost anything with a large specific heat
*could* work, but there may be practical advantages/disadvantages to
certain liquids (freezing and boiling points, etc).

If I go with the 2nd method, would I be better off taking apart a large
window AC unit, or taking apart a water chiller (from an old water
fountain)? The water chiller would already have 2 loops, which makes
things simpler, but it is probably not meant for such heavy use. With a
window AC unit, I would have to build a liquid-to-liquid heat
exchanger, such as two radiators immersed in an insulated box filled
with oil.

Thanks

If you really wanted to do this, you might make a tank around the hot
fins of a cheap window AC and fill it with oil or antifreeze to avoid
corrosion) and pump lots of 110 F oil through a heat exchanger to
warm 0.4 gpm of 60 F water to about 110 F. Z = 0 and E = 1-e^(-NTU)
= 0.9 makes NTU = 2.3 = 60A/200, so A = 6.7 ft^2, eg a 3"x10' copper
pipe inside a 4"x10' PVC pipe.

Or 5 3/4" x 10' copper pipes connected with Ts and street elbows.
Heating water with 1/3 the usual energy could be interesting, compared
to a $1K heat-pump water heater. Put an AC on a platform in the
basement with a fountain pump and a vertical PVC pipe near a tank water
heater with a thermosyponing fresh water loop, and air condition the
house with a circulation fan to the (dry) basement.

Wal-Mart sells Haier 5K Btu/h window ACs with a 9.7 COP for $98. I took
one apart today and found it wouldn't be hard to add a tank around the
hot fins without any recharging or replumbing.

Nick

That would be a good solution, because no connection would have to be
made to the outside, except if the hot water wasn't used frequently.
And if that happened, some type of solenoid valve could be actuated to
release some of the hot water outdoors and cycle in some cold water to
cool the AC.

At my apartment, unfortunately, I don't have access to the water
heater. Something to keep in mind when buying a house, I suppose.

I think I'm going to try cutting the piping in a conventional window AC
and adding longer refrigerant lines so that the hot fins are outside,
and the evaporator is inside. The compressor could technically be on
either side, but I might as well put it outside if I can. There would
also have to be a way to drain out the water which condenses inside --
shouldn't be too difficult.

On 18 Apr 2005 13:15:31 -0700, wrote:

That would be a good solution, because no connection would have to be
made to the outside, except if the hot water wasn't used frequently.
And if that happened, some type of solenoid valve could be actuated to
release some of the hot water outdoors and cycle in some cold water to
cool the AC.

At my apartment, unfortunately, I don't have access to the water
heater. Something to keep in mind when buying a house, I suppose.

I think I'm going to try cutting the piping in a conventional window AC
and adding longer refrigerant lines so that the hot fins are outside,
and the evaporator is inside. The compressor could technically be on
either side, but I might as well put it outside if I can. There would
also have to be a way to drain out the water which condenses inside --
shouldn't be too difficult.

Won't work, college boy.

You'll find out why soon enough.

BTW - I wouldn't be so hard on you if you hadn't tried to
impress everyone with your soon-to-be-born PH D, followed by your
COMPLETE lack of understanding of reality, and snotty attitude about
the whole thing.


Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/

What is with the anti-college attitude? I only brought up my Physics
background after you said:

"Nick Pine specializes in astral-physics - physics that only work in
another plane of reality. Take his nonsense accordingly. "

Placing myself with a crowd that you label in that manner is hardly
trying to "impress everyone". And I'm not about to get my PhD, I don't
know why you assumed that. And as far as attitude, I've been trying to
maintain composure and stick to the subject despire your incessant
flaming from the get-go. You seem to have made about twelve thousand
posts since google started their archive. After briefly scrolling
through the list, I see that they are almost all pointless banter from
someone who has nothing better to do.

wrote:

...I don't have access to the water heater...

That's good.

Nick

Back to the actual subject, if anyone can still bear to follow this
thread...

I think the only concern would be getting the pressure right in the
indoor part of the tubing. You want to make sure the refrigerant boils
and turns to a vapor in the indoor part, and you can set the
temperature at which this happens by the pressure in the tubing. If the
splicing of the tubing affected the pressure, some adjustable valves
might be able to compensate.

On 18 Apr 2005 13:48:27 -0700, wrote:

What is with the anti-college attitude? I only brought up my Physics
background after you said:

"Nick Pine specializes in astral-physics - physics that only work in
another plane of reality. Take his nonsense accordingly. "

Placing myself with a crowd that you label in that manner is hardly
trying to "impress everyone". And I'm not about to get my PhD, I don't
know why you assumed that.

Thought I recalled you saying it. My bad if wrong.

And as far as attitude, I've been trying to
maintain composure and stick to the subject despire your incessant
flaming from the get-go. You seem to have made about twelve thousand
posts since google started their archive.

I told you - I STARTED this group 10 years ago.

After briefly scrolling
through the list, I see that they are almost all pointless banter from
someone who has nothing better to do.

Blow me, asshole.

This is not
alt.collegeboy.wants.to.take.a.hacksaw.to.his.air. conditioner , so go
the **** away, you clueless twit.





Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/

On 18 Apr 2005 14:06:41 -0700, "nick pine"
wrote:

wrote:

...I don't have access to the water heater...

That's good.

Nick

Oh ...... my .....god .......

Nick and I agree on something !!!! Right when they're
electing a new pope !!!! It could be the coming of the anti-christ
after all !!!!!!


Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/

On 18 Apr 2005 14:13:49 -0700, wrote:

Back to the actual subject, if anyone can still bear to follow this
thread...

Nope, no one can. No one is interested in your amateur hack
bull****. Good by.


I think the only concern would be getting the pressure right in the
indoor part of the tubing. You want to make sure the refrigerant boils
and turns to a vapor in the indoor part, and you can set the
temperature at which this happens by the pressure in the tubing. If the
splicing of the tubing affected the pressure, some adjustable valves
might be able to compensate.

Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/

Hmm, shouldn't have used google-groups to post. I thought I was posting
just to alt.home.repair, but I guess it went to both groups.

wrote in message
oups.com...
Hmm, shouldn't have used google-groups to post. I thought I was posting
just to alt.home.repair, but I guess it went to both groups.

Yup, now twice as many people world wide know just how clueless you really
are.

Dude,

You are going to spend thousands of dollars to save a few tens of
dollars! If you open the refrigerand circuit without EPA certification
the penalty is 5 years jail and $27,500 fine! In addition if you don't
have the certification you won't be able to buy the proper refrigerant
for this application. This is NOT the stuff you can buy at Wal-Mart.
There are over 100 different refrigerants, only one will work in the
window unit. Has to do with compression ratios, specific heat,
operating pressures, metering oriface sizes and LOTS of other stuff.
Stick to electricity.

On the other hand, if you start working on this project, it should keep
you out of other kinds of trouble for a LONG time! :-) That is if
this thing doesn't blow up in your face and kill you. I have i brother
and a sister in law who are engineers and they don't mess with stuff
they don't understand. By the way, have you ever heard of the darwin
awards? Don't get your name on their lists.

Stretch

"stretch" wrote in message
ups.com...
Dude,

You are going to spend thousands of dollars to save a few tens of
dollars! If you open the refrigerand circuit without EPA certification
the penalty is 5 years jail and $27,500 fine! In addition if you don't
have the certification you won't be able to buy the proper refrigerant
for this application. This is NOT the stuff you can buy at Wal-Mart.
There are over 100 different refrigerants, only one will work in the
window unit. Has to do with compression ratios, specific heat,
operating pressures, metering oriface sizes and LOTS of other stuff.
Stick to electricity.

On the other hand, if you start working on this project, it should keep
you out of other kinds of trouble for a LONG time! :-) That is if
this thing doesn't blow up in your face and kill you. I have i brother
and a sister in law who are engineers and they don't mess with stuff
they don't understand. By the way, have you ever heard of the darwin
awards? Don't get your name on their lists.

Stretch


Funny thing is, he can buy what hes wanting...spend under 2 grand, and save
alot of effort attempting to re-invent the wheel.

I read his posts..and all I can do is say that I actually agree with Paul on
this one..
The guy has no clue what to call the parts hes working with, but...hes gonna
make a window unit work again after he opens it..
and if you say..500 mC, hes gonna be like....wha?
You tell him, and then its..but the compressor in the unit will do that
right?
No...dont tell this guy about the Dawin awards....if he wins this year, we
can all say we know someone..err...knew someone thats famous.

On Tue, 19 Apr 2005 01:18:22 -0400, "
wrote:


"stretch" wrote in message
oups.com...
Dude,

You are going to spend thousands of dollars to save a few tens of

Stretch


Funny thing is, he can buy what hes wanting...spend under 2 grand, and save
alot of effort attempting to re-invent the wheel.

No he can't. He's an EE. They can't do ANYTHING the simple
way.

I read his posts..and all I can do is say that I actually agree with Paul on
this one..

Watch it there, bud.


Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/

wrote:

wrote:

...I don't have access to the water heater...

That's good.

If he did, what would he do if the water heater tank were full of 110 F
water and he still needed AC?

Nick and I agree on something !!!!

I like cats too. I have four: Roo (blind), Creamsickle (stupid), Inviso
(feral), and Kidders (evil feline of doom.)

Nick

wrote:

[Whilst considering air conditioning while heating water for showers
with 1/3 the usual energy by disconnecting the condenser fan and making
an unpressurized tank around the hot fins of a $98 Haier 5K Btu/h 9.7
SEER Chinese-built AC (with remote :-) from Wal-Mart and pumping
antifreeze up through a vertical 4"x8' PVC pipe with a 10 W fountain
pump, said pipe containing 5 1/2" copper pipes connected with Ts and
street elbows to make a pressurized thermosyphon loop through a tank
water heater...]

...I don't have access to the water heater...

That's good.

If he did, what would he do if the water heater tank were full of
110 F water and he still needed AC?

He might pump 110 F pressurized water through a $40 400' flat spiral of
1/2" plastic pipe on the bottom of a 6' plastic swimming pool on the
balcony. A smaller pool would do, if the AC only works part-time.

Where I live, the average outdoor humidity ratio w = 0.0133 with water
vapor pressure Pa = 29.921/(0.62198/w+1) = 0.626 "Hg on an average day
in July, and air near 110 F water has a saturated vapor pressure Pw =
e^(17.863-9621/(110+460)) = 2.68 "Hg, so (using an ASHRAE swimming pool
formula) we can lose 5K Btu/h = 100A(Pw-Pa) with A = 24 ft^2 by
evaporating about 5/8 gallons per hour of water.

The hot water circ pump (Grainger's $120 4PC86 looks good) would also
improve the thermosyphon loop.

Nick

wrote:

[Whilst considering air conditioning while heating water for showers
with 1/3 the usual energy by disconnecting the condenser fan...

We might disconnect the fan motor to save more energy. This might ice
less in wintertime with another tank for the evaporator fins.

and making an unpressurized tank around the hot fins of a $98
Haier 5K Btu/h 9.7 SEER Chinese-built AC (with remote :-) from
Wal-Mart and pumping antifreeze up through a vertical 4"x8'
PVC pipe with a 10 W fountain pump, said pipe containing 5
1/2" copper pipes connected with Ts and street elbows to make
a pressurized thermosyphon loop through a tank water heater...]

what would he do if the water heater tank were full of
110 F water and he still needed AC?

He might pump 110 F pressurized water through a $40 400' flat spiral
of 1/2" plastic pipe on the bottom of a 6' plastic swimming pool on
the balcony. A smaller pool would do, if the AC only works part-time.

The hot water circ pump (Grainger's $120 4PC86 looks good) would also
improve the thermosyphon loop.

Then again, we might use 3/4" copper pipes for better thermosyphoning,
with another $10 10 watt fountain pump for the pool loop.

Nick

cat boi, get a job , get a woman, get a life, until then , just **** off
and die


wrote in message
...
On 18 Apr 2005 14:13:49 -0700, wrote:

Back to the actual subject, if anyone can still bear to follow this
thread...

Nope, no one can. No one is interested in your amateur hack
bull****. Good by.


I think the only concern would be getting the pressure right in the
indoor part of the tubing. You want to make sure the refrigerant boils
and turns to a vapor in the indoor part, and you can set the
temperature at which this happens by the pressure in the tubing. If the
splicing of the tubing affected the pressure, some adjustable valves
might be able to compensate.

Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's
http://pmilligan.net/pmtherm/

cat boi, u started no group, get a job, get a woman, get a life, otherwise
**** off and die


wrote in message
...
On 18 Apr 2005 13:48:27 -0700, wrote:

What is with the anti-college attitude? I only brought up my Physics
background after you said:

"Nick Pine specializes in astral-physics - physics that only work in
another plane of reality. Take his nonsense accordingly. "

Placing myself with a crowd that you label in that manner is hardly
trying to "impress everyone". And I'm not about to get my PhD, I don't
know why you assumed that.

Thought I recalled you saying it. My bad if wrong.

And as far as attitude, I've been trying to
maintain composure and stick to the subject despire your incessant
flaming from the get-go. You seem to have made about twelve thousand
posts since google started their archive.

I told you - I STARTED this group 10 years ago.

After briefly scrolling
through the list, I see that they are almost all pointless banter from
someone who has nothing better to do.

Blow me, asshole.

This is not
alt.collegeboy.wants.to.take.a.hacksaw.to.his.air. conditioner , so go
the **** away, you clueless twit.





Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's
http://pmilligan.net/pmtherm/

"nick pine" wrote in message
oups.com...

wrote:

wrote:

...I don't have access to the water heater...

That's good.

If he did, what would he do if the water heater tank were full of 110 F
water and he still needed AC?

Nick and I agree on something !!!!

I like cats too. I have four: Roo (blind), Creamsickle (stupid), Inviso
(feral), and Kidders (evil feline of doom.)

Nick


I like cats too. Breaded, fried, and with a little sweet and sour sauce,
the China Wok down the street does a pretty good job with 'em!

Hi,

I took this thread off of "sci.engr.heat-vent-ac" and "alt.hvac";
hopefully it will calm down a bit. It seems to be added to
"alt.energy.homepower", so I'll continue it there as well. If anyone is
just starting on this thread, I'm trying to come up with a way to make
an AC that works without a window, yet works better than those portable
units (I already own one, and I don't like it). There are "split" AC
systems pre-made, but I'm starting to think they aren't appropriate for
an apartment, even if money was not an issue. Upon moving out, the
refrigerant circuit would have to be dismantled. I'm not sure if
store-bought units provide valves to contain the refrigerant when doing
this; otherwise the refrigerant would have to be completely drained and
refilled every time. Additionally, they're fairly expensive, and though
building one is simple in principle, I might instead pursue another
route, which Nick just suggested.

Warning: This is a rather long post.

---------------

In reply to Nick's previous message:

That would actually be like a cross between two types of AC's: split
and portable units. It would be just like the portable unit in that the
compressor and the entire refrigerant circuit stays inside. Except
instead of using a fan and an air duct to remove the heat outdoors, it
would use a water circuit. And instead of discharging the exhaust right
out a window, like a portable unit, it would have a "second half"
outdoors, like a split unit. The nice thing about such a unit would be
that the exhaust "duct" could just be two thin, flexible hoses. If such
a unit was commercially produced (or should I say producable?), it
could have many applications. There are many people who work in
temporary locations, and use portable AC's. But a lot of these people
just point the AC at their immediate work area, and let the hot air
blast out the back. Usually this is because it's too inconvenient or
impractical to duct the hot air through their workplace. With smaller
water hoses, this wouldn't be as much of a problem. Don't get me wrong,
lugging around a swimming pool of tubing wouldn't allow for
portability, but I address an alternative later in the post.
Additionally, for temporary use, they could just plug into any cold
water supply and drain.

In order to get my store-bought portable unit to operate acceptably, I
need to use an enormous hose (bigger than the manufacturer supplied),
or else it will overheat and automatically shut off. Even in a very
small room, with the exhuast only having to go a foot or two. The
exhaust duct is ugly, and it is extremely hot. If the duct was more
than 10 feet or so, I bet the net result of using the portable AC would
be to heat the room, due to the heat radiating from the duct.

To add to Nick's idea:

What about using a second (smaller) compressor for the water circuit?
If the water was allowed to evaporate as it hit the hot coils, its
cooling ability would be much more efficient than if it stayed liquid
and just absorbed a small amount of heat as it passed. The compressor
would then pressurize the steam, lowering its boiling point, and it
would cool through the tubing Nick just mentioned, where it would
condense. There could then be a resevoir of water, to ensure that the
water in the next part of the tubing was almost entirely in the liquid
phase. Then it would go through some small flexible tubing to the
indoors, and cools the coils again. The pressure in various stages of
the tubing could be regulated somewhat by adjustable valves.

For me, a 6 foot pile of piping isn't that bad in the first place; I
never use my porch. But it would be nice to reduce that size, if
possible.

Some people might argue that having two compressors would reduce the
efficiency of the total system by a factor of about 1/2 purely because
of having double the number of compressors. However, where the water
compressor is doing "extra" work, the regular AC doesn't have to work
as hard, because its hot coils would be cooler. There would still
energy losses due to more moving parts, the viscocity of the water,
etc... The net efficiency would surely go down, and maybe it would go
to less than 1/2 its original value. It's just a question of whether it
goes to an acceptable level. People who buy portable units expect to
pay more for the units, and paying more for electricity is expected
too. The units are usually only bought because the user is unwilling to
go without AC, but the choice of AC units is limited by the
environment. Generally the application is temporary, and my case is no
exception (I won't live here very long). I have to guess that my
store-bought portable AC has an efficiency of 1/4 of even a cheap
window unit. A similar efficiency would be fine.

Also, I *do realize* a purely water-based AC would NOT work well
(alone). I am definitely not suggesting anything like that. Here, the
water is just transferring heat from a very hot coil to the less hot
outdoor air. The water would do that naturally, without a compressor
involved. It is NOT causing a SEPERATION of heat between two resevoirs;
ie: adding heat to the hotter side. And I realize that the water would
probably never been cooler than either the indoor or outdoor air. It
would only be cooler than the hot coils of the AC, and that's all that
matters. The phase changes between liquid and vapor would simply be to
absorb and release lots of energy quickly.

If such a unit was made commercially, the only benefit over a standard
portable AC would be having a thinner, flexible exhaust circuit. That
alone would open up possibilities. But for me, it would also mean that
I wouldn't have to cut into any refrigerant circuits. Which means not
having to worry about properly containing the refrigerant, getting a
vacuum pump, soldering the joints, putting more refrigerant back in
without letting in air/moisture, getting the pressure right, the list
goes on...

----------------------

Now, we had some arguements in the other newsgroup about making versus
buying, "reinventing the wheel", etc. Personally, I think it's more
like "building a wheel" to a certain specification. There will always
be some people who try to do things that they are destined to fail at,
and others who run away from anything challenging. Either extereme
isn't desirable. As far as that topic goes, I think it's best to just
leave it at that. But just for the record, if someone made a portable
AC unit approximately 20,000 BTU which had the design I described above
(with flexible, insulated water tubing), I would probably buy instead
of build. But that's besides the point, because I've never seen such a
thing.

One more addition to that already long post.

An analogy would be if you had a window AC sitting on a table, with the
hot fins surrounded by a box. In the box, you put a bunch of towels.
You pour some water onto the hot fins to cool them down, and then close
the box. The water quickly evaporates, and gets soaked up by the
towels. You bring them outside and squeeze them out. You then have a
bucket full of hot water, which you let cool down outside for awhile.
Then you dump the water back on the coils and repeat.

The analogy is crude, because a lot of the water would evaporate to the
outside air, etc. But it might aid in understanding that business I
described about adding a second water compressor.

I really apologize for making a 3rd post in a row, but the 1st post
should have read:

"The compressor would then pressurize the steam, RAISING its boiling
point, ..." -- ie trying to make it a liquid again.

wrote in message
oups.com...
Hi,

I took this thread off of "sci.engr.heat-vent-ac" and "alt.hvac";
hopefully it will calm down a bit. It seems to be added to
"alt.energy.homepower", so I'll continue it there as well. If anyone is
just starting on this thread, I'm trying to come up with a way to make
an AC that works without a window, yet works better than those portable
units (I already own one, and I don't like it).

Please explain what you do not like about the portable unit. I have just
purchased one for my bedroom and am now in the process of building a 2' high
pedestal so the exhaust hose can get a straight shot out the window. (I love
the concept of the portable unit because it is one less thing I have to deal
with to prepare the house for a hurricane.)

Vaughn

wrote:

...I'm trying to come up with a way to make an AC that works
without a window... There are "split" AC systems pre-made,
but I'm starting to think they aren't appropriate for an
apartment, even if money was not an issue. Upon moving out, the
refrigerant circuit would have to be dismantled. I'm not sure if
store-bought units provide valves to contain the refrigerant
when doing this; otherwise the refrigerant would have to be
completely drained and refilled every time.

In reply to Nick's previous message:

That would actually be like a cross between two types of AC's:
split and portable units. It would be just like the portable
unit in that the compressor and the entire refrigerant circuit
stays inside. Except instead of using a fan and an air duct to
remove the heat outdoors, it would use a water circuit. And
instead of discharging the exhaust right out a window, like
a portable unit, it would have a "second half" outdoors, like
a split unit. The nice thing about such a unit would be that
the exhaust "duct" could just be two thin, flexible hoses.

You might need the outdoor part if you had your own water heater and
the tank were hot and you needed more AC, but you are unlikely to need
one if you push the hot water back into the hot water pipe that enters
your apartment and the apartment tank is bigger and more people use its
hot water. Do you pay your own hot water bill?

...lugging around a swimming pool of tubing wouldn't allow for
portability, but I address an alternative later in the post.

You could make a flat spiral of 400' of 1/2" HDPE pipe in a fairly
lightweight 6 foot diameter disk.

Additionally, for temporary use, they could just plug into any cold
water supply and drain.

And miss the opportunity to heat water with 1/3 the usual energy... You
might open a solenoid valve to drain some hot water from the top of the
tank when/if the bottom gets to 110 F, in order to avoid the pipe and
pool on the balcony. You'd still have the 8' PVC pipe containing some
copper pipes.

What about using a second (smaller) compressor for the water circuit?

More money and energy and complexity.

If the water was allowed to evaporate as it hit the hot coils, its
cooling ability would be much more efficient than if it stayed liquid
and just absorbed a small amount of heat as it passed.

Evaporating water from the hot coils seems to invite mineral deposition
and corrosion. It also requires lots of surface. If you didn't mind
wasting energy, you might build an unpressurized plastic film
plate-type heat exchanger into the aquarium surrounding the hot fins.
If 5K Btu/h flows through A ft^2 of film with a 30A Btu/h-F conductance
and a 5 F temp diff, A = 5K/(5x30) = 33 ft^2, eg 16 1'x2' films spaced
1/4" apart. This would take the place of the 8' PVC pipe and the pipe
on the balcony. The "pool" might be a 6'x6' piece of plastic film
draped over 2 2x4s in a balcony corner, with a 10 W fountain pump.

Nick

Vaughn,

For me, there are two problems with portable unit. First, the one I
have is supposedly a 10,000 BTU unit, but it doesn't cool even a very
small room on an 85 degree day. Maybe a degree or two temperature drop,
if that. The coils aren't dirty, it's charged just fine, and there
aren't any leaks. The area right in front of the unit is cold, but an
equal amount of heat must "leak" back into the room. I've used it in
different locations, with the same results. Most of the problem
probably comes from the (very) hot exhaust hose. I'm considering adding
some insulation to it. Some heat might also come from the chassis of
the unit itself. Even if I had the ambition to built a better
fiberglass chassis and put insulation inside it, I think doing so would
cause the unit to overheat.

And the second problem is just that the hose is so large and ugly. And
since it's so hot, the unit has to be RIGHT next to a window. And if
the unit has to be right next to a window, and it only cools down the
area immediately in front of it, it pretty much limits the places you
can work.

Maybe the solution is to just assume that the units are 1/2 to 1/3
their stated BTU rating (when comparing to a window unit), and buy
accordingly, then insulate the exhaust duct. But most of the
consumer-oriented portable units only go up to 10,000-12,000 BTU (which
SHOULD be fine for a small room). If you want higher than that, you
have to go to the ones geared towards wharehouses and computer server
rooms. They're extremely expensive and you wouldn't want them in your
living room, even if you had the proper power hookups. So, unless
insulating the duct makes a WORLD of difference, I'm just going to
assume that portable AC's aren't for me - they're more for emergency
cooling and spot cooling.

Nick,

We do pay for hot water. I agree that if I pushed the water back into
the hot water pipe, it would probably be used up. But wouldn't doing so
require spending a lot of energy to force the water against the
pressure in the pipe? Or would you rely on thermosyphoning alone? I do
agree that it would be a shame to miss the energy-savings of heating
hot water, but I think I can wait until my home is permenantly setup
before attempting that part.

-------------

As far as evaporating the hot water, having the 2nd compressor, etc:

Since it would be a closed loop, any mineral deposits would flush out
once, and stay out (it will "auto-distill"). Distilled water could just
be used from the start. Corrosion of the hot fins on the AC is
definitely something worthy of consideration. Maybe something other
than water (but still not freon) could be used.

I think this type of system would be less efficient than a regular
window AC, and you wouldn't get the benefit of the hot water usage. But
I think it would still be more efficient than a portable AC, and about
equal in efficiency to the pool setup. If it was setup precisely (ie
water flow rate, pressures in different parts of the circuit), the
water compressor would barely be doing anything. It would just be
providing a "nudge" for the water vapor to go liquid again, and the
outside air would do the rest. And because the hot fins of the AC would
(hopefully) be MUCH cooler than they would be if the unit was mounted
in a window, the AC wouldn't have to work as hard (ie: less energy
spent).

---------------------

Can you explain further about the plastic films? What type of plastic
would be used, and what are its thermal properties? I'm not familiar
with that type of thing.

wrote:

We do pay for hot water.

Do you ever run out? Does everyone pay the same?

I agree that if I pushed the water back into the hot water pipe,
it would probably be used up. But wouldn't doing so require
spending a lot of energy to force the water against the pressure
in the pipe?

No, not at all. Since everything is under pressure, the pump only needs
to overcome the small friction loss in the pipe. You might use
Grainger's $102 5P428 1/35 HP pump, which draws less than 60 watts.

As far as evaporating the hot water, having the 2nd compressor, etc:

Since it would be a closed loop, any mineral deposits would flush out
once, and stay out (it will "auto-distill"). Distilled water could
just be used from the start. Corrosion of the hot fins on the AC is
definitely something worthy of consideration.

Evaporation happens when water meets air. Underwater fins won't
"evaporate" water unless it boils, which would kill AC efficiency. To
evaporate quickly, the fins must be wet and exposed to lots of airflow,
which sounds like a recipe for corrosion.

If it was setup precisely (ie water flow rate, pressures in different
parts of the circuit), the water compressor would barely be doing
anything.

How would you make a vacuum-tight seal around the hot fins?

It would just be providing a "nudge" for the water vapor
to go liquid again, and the outside air would do the rest.

How would the heat get into the air?

Can you explain further about the plastic films?

That wastes energy. Pushing hot water into the pipe is better.

Nick

wrote in message
oups.com...
Vaughn,

For me, there are two problems with portable unit. First, the one I
have is supposedly a 10,000 BTU unit, but it doesn't cool even a very
small room on an 85 degree day. Maybe a degree or two temperature drop,
if that. The coils aren't dirty, it's charged just fine, and there
aren't any leaks. The area right in front of the unit is cold, but an
equal amount of heat must "leak" back into the room.

Actually, that may be part of your problem. If your AC is blowing
hundreds of cubic feet of hot air out of your room, then an equal amount of
air must enter the room from *somewhere*. I have seen a few units that have
two hoses, but that may lead to other problems. Also, just because the
units come with 7 or 8 feet of hose, it does not mean that it is a good idea
to use it all. My unit will have about 18", of hose that will exhaust out
in a straight line.

I've used it in
different locations, with the same results. Most of the problem
probably comes from the (very) hot exhaust hose.

I doubt that is a significant part of your problem. Check with me in
three or four weeks and I will have some practical experience with my new
unit. Actually, my house has central air, but since we are "empty nesters"
we can get away with shutting it off at night and just running a small
bedroom unit. Also, our standby generator can power that bedroom unit in
the "powerless" days following a hurricane, but is not sufficient to power
our central air.

Vaughn

nick pine wrote:

Do you ever run out? Does everyone pay the same?

I've never run out of hot water in this place. It's split equally.

No, not at all. Since everything is under pressure, the pump only
needs
to overcome the small friction loss in the pipe. You might use
Grainger's $102 5P428 1/35 HP pump, which draws less than 60 watts.

So the water comes in from the cold pipe under pressure, and hopefully
doesn't lose much pressure throughout the circuit. Then it goes through
this small pump and gets forced into the hot water pipe, which is at an
almost equal pressure?

The one problem with this is that if the hot water tank *does* fill up,
I don't have access to it. I will just have to dump the hot water
directly down the drain and take more cold water. What was the gallon
per minute flow rate you quoted early (ballpark figure is fine)? Take
that flow rate and compare it to the average hot water usage for a few
apartment residences. During showers or dishwashing, the two flow rates
might be comparable. But otherwise I think the hot water tank would
fill up very fast. Filling the hot water tank quickly is good, in one
sense, but afterwards I will probably be back to dumping nearly a
thousand pounds of water per hour down the drain pipe.

I could COMBINE that idea with the outdoor cooling circuit idea. But it
wouldn't be as simple as just redirecting the heated water outdoors. I
would also have to stop taking in cold water, and take in the water
which is returning from the outdoor cooling circuit. It would require
four solenoid valves, or two 3-way solenoid junctions. Now that's fine.
But the REAL disadvantage for me is that there are now two constraints:

- Must have piping going to the hot and cold water pipes
- Must have piping going outdoors

So now the AC is somewhere near a power outlet, and there are 4 rather
long tubes coming out of it. At any given time, water is moving through
only two of the tubes - one hot and one cold. It would work fine in a
basement, but it's a little much for an apartment (at least mine). In
my apartment, one side faces the outdoors (porch & windows on this
side) and the plumbing runs on the opposite side (kitchen & bathroom on
this side).

I'd be fine with putting the AC on either side. Meaning I'd use either
the outdoor cooling circuit idea or the hot water pipe idea. But I'd
rather not do both. For me, I think I'd prefer the outdoor cooling
circuit, just so that I didn't have to dump all that water down the
drain. I know, it's free for me, and I was considering it before. But
I've recently come to think that it is rather wasteful of resources.
Also, they might notice around 2 gpm * 1440 minutes per day = 2880
gallons per day of additional cold water usage.

Evaporation happens when water meets air. Underwater fins won't
"evaporate" water unless it boils, which would kill AC efficiency. To
evaporate quickly, the fins must be wet and exposed to lots of
airflow,
which sounds like a recipe for corrosion.

Well, here's what I was planning. The water would start off as steam,
then pass through the compressor, raising its boiling point (turns
liquid at a lower temperature). It would go through a condenser
(basically a radiator), where it would cool and turn liquid. It would
then head towards the hot fins of the indoor AC. When it got there, the
water tubing would enter a chamber which is hot (from the AC fins) and
is at a lower pressure (because the water would be expanding into a
larger volume). You're right that it would require a vacuum-tight seal.
But the fins wouldn't be underwater, and no outside air would pass
through them.

BTW: To avoid corrosion, maybe use glycol mixed with an anti-corrosive
agent instead of water.

How would you make a vacuum-tight seal around the hot fins?

I'm not sure. Some tight rubber gaskets around the refrigerant tubing
might work. Without a vacuum-tight seal, this evaporative water circuit
couldn't be used (at least not *directly*).

Awhile ago, I described an *indirect* approach for transferring heat
between two closed circuits (the liquid-liquid heat exchanger). But
I've since decided that is probably a poor method (performance
degredation).

Maybe instead of rubber gaskets, the chamber could be built around the
fins with a small clearance wherever the refrigerant tubing got in the
way. Then I could weld around all the clearances.

How would the heat get into the air?

The heat would dissapate from the tube into the air naturally; the
water (vapor) is hotter than the air. A standard radiator/condenser
would do the trick. A fan would help.

Can you explain further about the plastic films?

That wastes energy. Pushing hot water into the pipe is better.

Nick

I just did a google search for the following:

"water circuit" air conditioner
water tower air conditioning

I found information on two types of AC systems which use water circuits
to transfer heat. The first was used mostly in large boats / yachts.
These people use closed circuit fresh-water circuits to directly
distribute heat to / absorb heat from different parts of their yachts.
One such system is described at the following web page:

http://mail.veco.net:82/veco/sito/fai_da_te/eng/ac1.htm

On that web page, they describe three types of systems:

1) Direct expansion, single room unit. Pretty much a standard window AC
made for marine use.

2) Central compressor, direct expansion. Basically a multi-split.

3) "central systems with chilled (or heated) water distribution to
several fan coils "

The THIRD system is the one I am interested in. It would be equivalent
to putting almost everything AC-related outdoors. A water circuit would
just come indoors, and pass through a fan-assisted radiator. A small
radiator is capable of doing the job; I know of people who cool large
areas (sucessfully!) by passing well water through a truck radiator.
The water just has to be kept cold enough (well-water temperature is
fine). Anyway, onto the second type of system.

The second type of system relies on a cooling tower, and is often found
in large commercial buildings or hotels. I've actually seen these
before and talked to some people who service them, so I don't know why
I didn't remember them earlier. It's fairly similar to what we were
talking about with the cooling circuit on the porch, though there are
some differences. Here are the basic principles, which I've just copied
and pasted from another site:

- A cooling tower blows air through a stream of water so that some of
the water evaporates.
- Generally, the water trickles through a thick sheet of open plastic
mesh.
- Air blows through the mesh at right angles to the water flow.
- The evaporation cools the stream of water.
- Because some of the water is lost to evaporation, the cooling tower
constantly adds water to the system to make up the difference.

That is actually just one type. There are both direct (open circuit)
and indirect (closed circuit) versions. A good source of basic
information about them is:

http://www.cti.org/whatis/coolingtowerdetail.shtml

With an direct (open circuit) cooling system, only regular water can be
used in the circuit, because it will constantly be evaporating and
being replaced. So the fins would probably need to be plated with
something which is corrosion-resistant. With an indirect (closed
circuit) cooling system, the main cooling circuit doesn't have to be
filled with water, and an anti-corrosion additive could be used.

Now, the "usual" purpose of these cooling towers is to increase
efficiency. But for me, it has the side-effect of letting me place the
AC indoors, with the hot fins being cooled by the water stream. I have
a feeling that THIS system would be best in efficiency (rather than the
other system - used on boats). The water might be around 90 - 110
degrees (20 or so degrees above outdoor temp), and the fins might be
around 190 degrees. The difference in temperature between the water and
the hot fins would be rather large, so heat transfer would be rapid.
With the boat system described earlier, the cold water might be 60 - 70
degrees. The room temperature would only be about 10 - 20 degrees
hotter than this. So heat transfer wouldn't be as rapid.

The one advantage of the "boat system" is that the entire AC unit could
be placed outdoors. On the indoor side, there would be no tubing above
room temperature. Which eliminates the problem I have had with my
portable unit: heat leaking back into the room. As far as I'm
concerned, both systems are adequate; ease/difficulty in construction
will be the deciding factor.

Well, previously I said that I would just buy a system if I could find
a water-based system which was of about the size I need.

http://www.flagshipmarine.com/selfcontained.html

Starting price: $1,189 for a 16,500 BTU unit that would go indoors, and
be water-cooled to an outdoor "cooling tower" (this I know I can make).

http://www.flagshipmarine.com/chiller.html

Starting price: $3,300 for a 18,000 BTU unit that would be almost
completely outdoors, except a cold water circuit and a fan-assisted
indoor radiator. Since it is intended for marine use, it is probably
water-cooled, so an outdoor "cooling tower" might still be needed.

The 1st one is cheaper, and probably more efficient, so I might just
buy that. I could either hide it in a chest / cabinet (with an air
grille), or make a fiberglass chassis for it.

On 20 Apr 2005 13:14:18 -0700, wrote:

nick pine wrote:

Do you ever run out? Does everyone pay the same?

I've never run out of hot water in this place. It's split equally.

No, not at all. Since everything is under pressure, the pump only
needs
to overcome the small friction loss in the pipe. You might use
Grainger's $102 5P428 1/35 HP pump, which draws less than 60 watts.

So the water comes in from the cold pipe under pressure, and hopefully
doesn't lose much pressure throughout the circuit. Then it goes through
this small pump and gets forced into the hot water pipe, which is at an
almost equal pressure?

The one problem with this is that if the hot water tank *does* fill up,

You may, just possibly, be the biggest ****ing moron ever to
graduate college with a technical degree.


Click every day here to feed an animal that needs you today !!!

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Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
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On Wed, 20 Apr 2005 21:04:37 GMT,
wrote:

On 20 Apr 2005 13:14:18 -0700, wrote:

nick pine wrote:

Do you ever run out? Does everyone pay the same?

I've never run out of hot water in this place. It's split equally.

No, not at all. Since everything is under pressure, the pump only
needs
to overcome the small friction loss in the pipe. You might use
Grainger's $102 5P428 1/35 HP pump, which draws less than 60 watts.

So the water comes in from the cold pipe under pressure, and hopefully
doesn't lose much pressure throughout the circuit. Then it goes through
this small pump and gets forced into the hot water pipe, which is at an
almost equal pressure?

The one problem with this is that if the hot water tank *does* fill up,

You may, just possibly, be the biggest ****ing moron ever to
graduate college with a technical degree.

Including Nick. And that's saying a LOT !!!!


Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/

On 20 Apr 2005 14:04:02 -0700, wrote:

Well, previously I said that I would just buy a system if I could find
a water-based system which was of about the size I need.

http://www.flagshipmarine.com/selfcontained.html

Starting price: $1,189 for a 16,500 BTU unit that would go indoors, and
be water-cooled to an outdoor "cooling tower" (this I know I can make).

Yep - you got Nick beat, I have to admit it.

At least his stupid ideas are cheap.


Click every day here to feed an animal that needs you today !!!

http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'

HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/
Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/

Short of moving, or cutting a hole in the wall (and getting evicted),
what would YOU do? (I'm expecting some not-very-funny comment about
working in the car/bath tub... or possibly something more childish like
"die")

Back when I purchased my portable AC, it was somewhere near $1000
(slightly less). Even if it worked a little better, it will never be
able to cool more than a bedroom; it's only about 10,000 BTU. Portable
units don't come much bigger than that without spending absurd amounts
of money.

You still haven't posted a single intellegent comment, of either a
technical or theoretical nature, which backs up anything you've said.