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Air conditioning costs, an idea
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| Gary Helfert 2005-08-28, 2:21 am |
| Many parts of the country the days can be exstreamly hot and the nights
quite cool.
It seems if you could run the ac at night and store the cold some how for
use in the day, it would be so much more efficient.
I thought of making the liquid freon at night and releasing it into the
system during the day but it occurred to me what would I do with all the
freon gas formed during the daytime cooling.
The only solution I came up with to "store cold", was to make ice at night
and circulate air over it during the day for cooling.
Any feedback on the practicality of this solution appreciated.
| |
| Jim Baber 2005-08-28, 3:21 am |
| Jim Baber replys:
Gary, for your information, the storage of cooled refrigerant for
use in the hot time of day is done in some commercial systems. I know
that California State university at Fresno does freeze ice at night and
then uses chilled fluid from the thawing of that ice as coolant in their
air conditioning system the next day. They are able to make use of the
considerably lower cost of the energy (electricity) at night as opposed
to the daytime energy costs to greatly reduce the daytime air
conditioning cost. Daytime summer temperatures can and do frequently
exceed 100 F., while the nights get down to 60 - 73 F.
Gary Helfert wrote:
>Many parts of the country the days can be exstreamly hot and the nights
>quite cool.
>It seems if you could run the ac at night and store the cold some how for
>use in the day, it would be so much more efficient.
>
>I thought of making the liquid freon at night and releasing it into the
>system during the day but it occurred to me what would I do with all the
>freon gas formed during the daytime cooling.
>
>The only solution I came up with to "store cold", was to make ice at night
>and circulate air over it during the day for cooling.
>
>Any feedback on the practicality of this solution appreciated.
>
>
>
>
| |
| the seventh sign 2005-08-28, 4:21 am |
| Gary Helfert wrote:
> Many parts of the country the days can be exstreamly hot and the nights
> quite cool.
> It seems if you could run the ac at night and store the cold some how for
> use in the day, it would be so much more efficient.
>
> I thought of making the liquid freon at night and releasing it into the
> system during the day but it occurred to me what would I do with all the
> freon gas formed during the daytime cooling.
>
> The only solution I came up with to "store cold", was to make ice at night
> and circulate air over it during the day for cooling.
>
> Any feedback on the practicality of this solution appreciated.
>
>
Make an old style ice house with modern insulating materials use a big
giant copper coil and fill it with ammonia gas put a fire to one end of
the coil (Outside) and voila nice cool room. if the pipes break how ever
it might be a dangerous room too. venting is a must i would bet and
safety doors too so no child gets locked and frozen in too. then vent
the cool to the house i guess with a pump of some kind.
TSS
| |
| Anthony Matonak 2005-08-28, 6:21 am |
| Gary Helfert wrote:
> Many parts of the country the days can be exstreamly hot and the nights
> quite cool.
> It seems if you could run the ac at night and store the cold some how for
> use in the day, it would be so much more efficient.
....
Some universities and industrial plants use something like this.
I'm not sure of the details but I seem to recall they use very
large tanks of water that they cool at night. Perhaps they use
brine as it has a lower freezing point. It helps if you have
time of use metering as you'll get a cheaper rate on your power
at night.
Anthony
| |
| Gary Helfert 2005-08-28, 9:21 am |
| I didn't really consider the lower cost of electricity at night. That would
be an added benefit. I was thinking that compressing freon at 60 degree
night time temperatures would surely be more cost efficient that trying to
compress it at 100 degree day time temperatures.
"Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
news:7_aQe.702$MN5.23@newssvr25.news.prodigy.net...
> Many parts of the country the days can be exstreamly hot and the nights
> quite cool.
> It seems if you could run the ac at night and store the cold some how for
> use in the day, it would be so much more efficient.
>
> I thought of making the liquid freon at night and releasing it into the
> system during the day but it occurred to me what would I do with all the
> freon gas formed during the daytime cooling.
>
> The only solution I came up with to "store cold", was to make ice at night
> and circulate air over it during the day for cooling.
>
> Any feedback on the practicality of this solution appreciated.
>
| |
| Ed Earl Ross 2005-08-28, 12:21 pm |
| Anthony Matonak wrote:
> Gary Helfert wrote:
>
>
> ...
>
> Some universities and industrial plants use something like this.
> I'm not sure of the details but I seem to recall they use very
> large tanks of water that they cool at night. Perhaps they use
> brine as it has a lower freezing point. It helps if you have
> time of use metering as you'll get a cheaper rate on your power
> at night.
>
> Anthony
Liquid desiccant cooling requires 25% the energy of conventional
refrigeration. See:
http://www.google.com/url?sa=t&ct=r...ZJ63-sAGyxaGxCg
The initial cost is considered too high for use in homes; although,
they are available for commercial buildings.
--
Humbly--Ed
"If the man doesn't believe as we do,
we say he is a crank, and that settles it.
I mean, it does nowadays, because now we
can't burn him." (Mark Twain)
| |
| SQLit 2005-08-28, 12:21 pm |
|
"Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
news:7_aQe.702$MN5.23@newssvr25.news.prodigy.net...
> Many parts of the country the days can be exstreamly hot and the nights
> quite cool.
> It seems if you could run the ac at night and store the cold some how for
> use in the day, it would be so much more efficient.
>
> I thought of making the liquid freon at night and releasing it into the
> system during the day but it occurred to me what would I do with all the
> freon gas formed during the daytime cooling.
>
> The only solution I came up with to "store cold", was to make ice at night
> and circulate air over it during the day for cooling.
>
> Any feedback on the practicality of this solution appreciated.
A/C systems have a given amount of freon. This is recycled to create the
cold. Your concept would require HUGE tanks one for the compressed freon and
one for the uncompressed gas. This would create some problems, nothing that
could not be over come.
Most single residential units hold less than 10 pounds of freon. Your
talking about a home having 2000 to 4000 pounds of freon. Just following
your idea here. At several dollars a pound I believe you can see the
problem here. Let alone the licenses needed to have that much freon.
There are commercial "ice plants". They use anti freeze and water and lower
the storage containment building to about a "slushy" consistency. Bank One
Ball Park in Phoenix has one of these, so does the Aladdin Hotel in Lost
Wages. These tanks are not small nor are the machines that are used.
I am unaware of any residential "ice plants". Smallest one I have ever seen
was 4000 tons, a pair of 2000 ton machines working together.
Lots of large commercial places have what is called "thermal storage". Water
cooled during the off peak times, and then recycled during the day when
electricity rates are higher. Smallest one I have ever seen is 1000
gallons.
| |
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| nicksanspam@ece.villanova.edu 2005-08-28, 4:21 pm |
| Gary Helfert <ghelfert@worldnet.att.net> wrote:
>I didn't really consider the lower cost of electricity at night.
>That would be an added benefit.
That might be the main benefit.
>...compressing freon at 60 degree night time temperatures would surely
>be more cost efficient that trying to compress it at 100 degree
>day time temperatures.
I'm not sure that makes much difference, esp since ACs are designed to
work at higher outdoor air temps. And you want to make ice vs 75 F air?
OTOH, you might flood the house with cool air at night and button it up
during the day, and evaporative cooling is more efficient in cooler air.
NREL says an average 74.1 F July day in Allentown, PA is 63.6 min and 84.5
max, with w = 0.0122, fairly humid, so we wouldn't want to add water to
house air, but we might add more thermal mass in the basement and let cool
air flow up through the attic at night with a couple of 2'x2' vents with
1-way lightweight plastic film dampers and a fan to circulate air between
the basement and upstairs during the day. A fan with an 80 F thermostat
would make this a bit more efficient. The max external ventilation below
is 1303-400 = 903 cfm at t = 16 hours, when it's 65 outdoors.
10 PI=4*ATN(1)
20 G=400'house conductance (Btu/h-F)
30 C=8000!'house capacitance (Btu/F)
40 A=4'vent area (ft^2)
50 H=16'height (ft)
60 ELEN=800'monthly indoor electrical energy use (kWh/mo)
70 ELHH=3412*ELEN/30/24'hourly electrical heat load (Btu)
80 FOR D=1 TO 10'day
90 FOR T=0 TO 23'hour
100 TA=74.1+(84.5-74.1)*SIN(2*PI/24*T)'outdoor temp (F)
110 IF TA<TC THEN GA=400+16.6*A*SQR(H*(TC-TA)) ELSE GA=400
120 TC=TC+(ELHH+(TA-TC)*GA)/C'new mass temp (F)
130 IF D=10 AND T/2-INT(T/2) = 0 THEN PRINT 200+T;"'";T,TA,GA,TC
140 NEXT:NEXT
outdoor thermal indoor
hour temp (F) conductance temp (F)
0 74.1 400 72.65117
2 79.3 400 74.10437
4 83.10667 400 75.82768
6 84.5 400 77.58048
8 83.10666 400 79.09271
10 79.3 564.7291 80.1314
12 74.1 1057.899 79.8982
14 68.9 1249.352 78.00316
16 65.09333 1303.31 75.24973
18 63.7 1249.099 72.79834
20 65.09334 1096.828 71.50678
22 68.9 819.7627 71.61571
With no indoor electrical use, C = 2300 Btu/F (with no extra thermal mass)
is enough to limit the max indoor temp to 80 F, but a US average 800 kWh of
electrical use adds 3800 Btu/h of heat (like a window AC), so more mass is
required. If the house has 2000 Btu/F of inherent mass, we might add 6000
more in the basement ceiling, eg 500ft^2x2" of water in poly film ducts.
Nick
Tired of Iraq? Do something about it. Learn to halve your energy use
while having fun with math and science.
Join PE Drew Gillett and PhD Rich Komp and me for a workshop on Solar House
Heating and Natural Cooling Strategies at the first Pennsylvania Renewable
Energy Festival on Saturday September 24, 2005 near Allentown. See
http://www.paenergyfest.com/workshop-info.shtml
| |
| William P. N. Smith 2005-08-28, 6:21 pm |
| "Gary Helfert" <ghelfert@worldnet.att.net> wrote:
>Many parts of the country the days can be exstreamly hot and the nights
>quite cool.
>It seems if you could run the ac at night and store the cold some how for
>use in the day, it would be so much more efficient.
Thermal stores can be made of water, rock, or anything with a
sufficiently high thermal mass. Using ice gives you a much more
compact store at the expense of designing the system to run at zero
degrees C.
Even something as simple as concrete construction can help moderate
day/night temperatures.
| |
| zenboom 2005-08-28, 6:21 pm |
|
"Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
news:rUhQe.14$yQ1.0@newssvr17.news.prodigy.com...
> I didn't really consider the lower cost of electricity at night. That
would
> be an added benefit. I was thinking that compressing freon at 60 degree
> night time temperatures would surely be more cost efficient that trying to
> compress it at 100 degree day time temperatures.
>
> "Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
> news:7_aQe.702$MN5.23@newssvr25.news.prodigy.net...
for[color=darkred]
night[color=darkred]
>
to distribute your compression cycle over 12 hrs would I guess require much
larger coolent system and charge...? would this pay off ?
| |
| Gary Helfert 2005-08-28, 10:21 pm |
| If you have an outdoor swimming pool maybe you can chill this down at night
and somehow use this water to cool the house during the day. If you seldon
use your pool for swimming this might be a practical use.
"Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
news:rUhQe.14$yQ1.0@newssvr17.news.prodigy.com...
>I didn't really consider the lower cost of electricity at night. That would
>be an added benefit. I was thinking that compressing freon at 60 degree
>night time temperatures would surely be more cost efficient that trying to
>compress it at 100 degree day time temperatures.
>
> "Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
> news:7_aQe.702$MN5.23@newssvr25.news.prodigy.net...
>
>
| |
| daestrom 2005-08-29, 6:21 pm |
|
"Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
news:7_aQe.702$MN5.23@newssvr25.news.prodigy.net...
> Many parts of the country the days can be exstreamly hot and the nights
> quite cool.
> It seems if you could run the ac at night and store the cold some how for
> use in the day, it would be so much more efficient.
>
> I thought of making the liquid freon at night and releasing it into the
> system during the day but it occurred to me what would I do with all the
> freon gas formed during the daytime cooling.
>
> The only solution I came up with to "store cold", was to make ice at night
> and circulate air over it during the day for cooling.
>
> Any feedback on the practicality of this solution appreciated.
You should probably abandon the idea of storing liquid freon at night and
capturing the gas formed during the day. Freon-22absorbs about 60 BTU/lbm.
So if you wanted to get the equivalent of a 3 Ton A/C unit operating 1/2 the
time for six hours, that would be 3Ton * 12000 BTU-Ton/hr * 3 hrs /(60
BTU/lbm) = 1800 lbm of Freon. And that much Freon, as a gas would take up
about 900 ft^3 of storage at 70F and 85 psig. Pretty large storage tank.
But the idea of using ice is a good one. Because ice absorbs about 144
BTU/lbm when it melts, you could get the same amount of cooling with: 3Ton *
12000 BTU-Ton/hr * 3 hrs / (144 BTU/lbm) = 750 lbm of water. In the liquid
state, that would be about 90 gallons.
You'd have to make some accomodation for expansion as it freezes of course.
How you circulate air around it to cool it, and how you re-freeze it every
night would have to be worked out. But as others say, it's been done on
commercial scale, so there's no absolute reason it couldn't be done on a
residential level.
To get maximum benefit, it would be best if your electricity was on TOU
(time-of-use) tariff. Depending on how much *other* electricity you use, it
may/may-not be worth it from a cost standpoint though.
daestrom
>
| |
|
| Ice banking. Make ice at night. We installed a system in Mooresville, NC
like this. It makes slabs of ice at night that drop into a pit in the
ground. The ice water is then pumped through a water coil in an air handler
during the day. Works great.
"Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
news:7_aQe.702$MN5.23@newssvr25.news.prodigy.net...
> Many parts of the country the days can be exstreamly hot and the nights
> quite cool.
> It seems if you could run the ac at night and store the cold some how for
> use in the day, it would be so much more efficient.
>
> I thought of making the liquid freon at night and releasing it into the
> system during the day but it occurred to me what would I do with all the
> freon gas formed during the daytime cooling.
>
> The only solution I came up with to "store cold", was to make ice at night
> and circulate air over it during the day for cooling.
>
> Any feedback on the practicality of this solution appreciated.
>
>
| |
| Dave Hinz 2005-08-30, 1:21 pm |
| On Mon, 29 Aug 2005 23:58:13 GMT, Tim <beachcooler@earthlink.net> wrote:
> Ice banking. Make ice at night. We installed a system in Mooresville, NC
> like this. It makes slabs of ice at night that drop into a pit in the
> ground. The ice water is then pumped through a water coil in an air handler
> during the day. Works great.
You know, you've got me thinking now. So, how about a big thermal
mass,like in the dead space under the basement stairs? Sand or
something that has good conductivity and mass, pipes running through it.
Chiller to cool it during the cheap off-peak electricity times, and then
dump heat into that during the day to "get the cold back" (yeah, I know,
heat doesn't flow that way.) In the winter, that's that much more
thermal mass...
| |
| Arnold Walker 2005-08-30, 1:21 pm |
|
"Dave Hinz" <DaveHinz@spamcop.net> wrote in message
news:3njccsF1otgfU5@individual.net...
> On Mon, 29 Aug 2005 23:58:13 GMT, Tim <beachcooler@earthlink.net> wrote:
handler[color=darkred]
>
> You know, you've got me thinking now. So, how about a big thermal
> mass,like in the dead space under the basement stairs? Sand or
> something that has good conductivity and mass, pipes running through it.
> Chiller to cool it during the cheap off-peak electricity times, and then
> dump heat into that during the day to "get the cold back" (yeah, I know,
> heat doesn't flow that way.) In the winter, that's that much more
> thermal mass...
Or you can do like some of the Southern Ice plants.
Kick down large vaccum on a coil with water in it and freeze your ice in
your ice house.
Absorpsive cycle without the ammonia or other refrig. media.
Some used steam and some used electric vaccuum compressors.
If you are using steam ......it can also make that coil hot.
>
----== Posted via droptable.com - Unlimited-Uncensored-Secure Usenet News==----
http://www.droptable.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
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| |
|
|
"the seventh sign" <die.now.spammers@internet.now> wrote in message
news:11h2n7si7suchde@corp.supernews.com...
> Gary Helfert wrote:
> Make an old style ice house with modern insulating materials use a big
> giant copper coil and fill it with ammonia gas put a fire to one end of
> the coil (Outside) and voila nice cool room. if the pipes break how ever
> it might be a dangerous room too. venting is a must i would bet and safety
> doors too so no child gets locked and frozen in too. then vent the cool to
> the house i guess with a pump of some kind.
Copper and ammonia are a no no !!
Yes, they do use ammonia in small absorsion plants with a naked flame, but
they are small and made of steel pipes, and great care is taken that the
ammonia cannot get near the flame.
Not sure what you are suggesting here with fire one end and cool the other,
but in over 40 years of experience in refrigeration I have never seen such a
device.
| |
|
|
"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in message
news:BbKQe.51548$Hx4.38256@twister.nyroc.rr.com...
>
> "Gary Helfert" <ghelfert@worldnet.att.net> wrote in message
> news:7_aQe.702$MN5.23@newssvr25.news.prodigy.net...
>
> You should probably abandon the idea of storing liquid freon at night and
> capturing the gas formed during the day. Freon-22absorbs about 60
> BTU/lbm. So if you wanted to get the equivalent of a 3 Ton A/C unit
> operating 1/2 the time for six hours, that would be 3Ton * 12000
> BTU-Ton/hr * 3 hrs /(60 BTU/lbm) = 1800 lbm of Freon. And that much
> Freon, as a gas would take up about 900 ft^3 of storage at 70F and 85
> psig. Pretty large storage tank.
>
> But the idea of using ice is a good one. Because ice absorbs about 144
> BTU/lbm when it melts, you could get the same amount of cooling with: 3Ton
> * 12000 BTU-Ton/hr * 3 hrs / (144 BTU/lbm) = 750 lbm of water. In the
> liquid state, that would be about 90 gallons.
>
> You'd have to make some accomodation for expansion as it freezes of
> course. How you circulate air around it to cool it, and how you re-freeze
> it every night would have to be worked out. But as others say, it's been
> done on commercial scale, so there's no absolute reason it couldn't be
> done on a residential level.
>
> To get maximum benefit, it would be best if your electricity was on TOU
> (time-of-use) tariff. Depending on how much *other* electricity you use,
> it may/may-not be worth it from a cost standpoint though.
>
> daestrom
Another consideration is the compression ratio of the compressor, chilling
down anything to a lower temperature than used in simple air conditioning
lowers the efficiency of the compressor by having a higher compression
ratio, and before jumping into a system like this, it should be looked into.
It could well be that with the larger equipment required and the lower
efficiency, nothing would be gained.
| |
| Solar Flare 2005-08-30, 9:21 pm |
| Doesn't just plain water in a tank have a higher specific heat than sand or
dry materials?
Much more conductive for heat exchange also?
A bit of chlorine or preservative may ned to be added from time to time.
"Dave Hinz" <DaveHinz@spamcop.net> wrote in message
news:3njccsF1otgfU5@individual.net...
> On Mon, 29 Aug 2005 23:58:13 GMT, Tim <beachcooler@earthlink.net> wrote:
handler[color=darkred]
>
> You know, you've got me thinking now. So, how about a big thermal
> mass,like in the dead space under the basement stairs? Sand or
> something that has good conductivity and mass, pipes running through it.
> Chiller to cool it during the cheap off-peak electricity times, and then
> dump heat into that during the day to "get the cold back" (yeah, I know,
> heat doesn't flow that way.) In the winter, that's that much more
> thermal mass...
| |
| the seventh sign 2005-08-31, 2:21 am |
| RamRod Sword of Baal wrote:
> "the seventh sign" <die.now.spammers@internet.now> wrote in message
> news:11h2n7si7suchde@corp.supernews.com...
>
>
> Copper and ammonia are a no no !!
>
> Yes, they do use ammonia in small absorsion plants with a naked flame, but
> they are small and made of steel pipes, and great care is taken that the
> ammonia cannot get near the flame.
>
> Not sure what you are suggesting here with fire one end and cool the other,
> but in over 40 years of experience in refrigeration I have never seen such a
> device.
Back when refrigeration was first invented they used an open flame with
a totally enclosed tube of some kind of coil acting as a cooler.
when you heat ammonia gas enclosed in this it cools where the heat is
not applied.
you would not have seen such a device in your 40 years of experience
because it was used in first generation refrigerators. i think this is
50 year old idea or so.
what this process is called i have no idea.
Hear is what i am thinking.
A Crosley "Icy Ball" (in operating condition): These refrigerators were
made for farms before rural electrification (approximately after World
War II). Ammonia and water charged (after regeneration over a kerosene
burner), the box temperature of 43 degrees Fahrenheit could be
maintained over a 24- to 40-hour period, while making ice cubes.
TSS
| |
|
|
"the seventh sign" <die.now.spammers@internet.now> wrote in message
news:11hacqhkqhgr032@corp.supernews.com...
> RamRod Sword of Baal wrote:
>
> Back when refrigeration was first invented they used an open flame with a
> totally enclosed tube of some kind of coil acting as a cooler.
> when you heat ammonia gas enclosed in this it cools where the heat is not
> applied.
>
> you would not have seen such a device in your 40 years of experience
> because it was used in first generation refrigerators. i think this is 50
> year old idea or so.
> what this process is called i have no idea.
>
> Hear is what i am thinking.
> A Crosley "Icy Ball" (in operating condition): These refrigerators were
> made for farms before rural electrification (approximately after World War
> II). Ammonia and water charged (after regeneration over a kerosene
> burner), the box temperature of 43 degrees Fahrenheit could be maintained
> over a 24- to 40-hour period, while making ice cubes.
Icy balls were a device with two balls, with a pipe in between, the ammonia
water mixture was forced into one ball by tipping the device on its end,
then the ball with the liquid was heated and the other ball was place in a
container with water in, the ammonia was the forced from the water ammonia
mixture (by the heat) and then condensed in the steel ball that was sitting
in the water. After a given time almost all of the ammonia was in one ball
and water in the other.
At that time the steel ball containing the ammonia was placed in an 'ice
chest' and the steel ball with the water in was on the outside, once the
water had cooled, the ammonia would start to evaporate getting that ball
very cold, and pass through the pipe and be absorbed into the water.
The modern absorbsion refrigerator works on a similar principle, but is
continuous in its operation. It has hydrogen and sometime methyl chloride in
with the ammonia and water mixture to improve the operation. It can use a
flame, an electric element even steam for a heat source.
While not having seen one I have read about it many times, and quite frankly
it is miles away from a device like >>Make an old style ice house with
modern insulating materials use a big giant copper coil and fill it with
ammonia gas put a fire to one end of the coil (Outside) and voila nice cool
room.<<
Ammonia attacks copper, hence the use of steel.
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