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Home > Archive > Alternative Power sources > July 2005 > silica-gel packets as room dehumidifiers
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silica-gel packets as room dehumidifiers
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| no_child_left_unleashed@yahoo.com.sg 2005-07-24, 9:06 pm |
| Noticed that new-in-p
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| Couple hundred pound yes? maybe?
Are you serious?
Dido
<no_child_left_unleashed@yahoo.com.sg> wrote in message
news:1122199102.337590.79940@f14g2000cwb.googlegroups.com...
> Noticed that new-in-p
>
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| Oscar_Lives 2005-07-24, 9:06 pm |
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<no_child_left_unleashed@yahoo.com.sg> wrote in message
news:1122199102.337590.79940@f14g2000cwb.googlegroups.com...
> Noticed that new-in-p
>
Try shoving several up your XXX and see if it changes your humidity.
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| I came across dummy's but you take the cake
Dido
"Oscar_Lives" <nospam@nospam.net> wrote in message
news:ljNEe.178479$_o.9167@attbi_s71...
>
> <no_child_left_unleashed@yahoo.com.sg> wrote in message
> news:1122199102.337590.79940@f14g2000cwb.googlegroups.com...
>
> Try shoving several up your XXX and see if it changes your humidity.
>
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| William P. N. Smith 2005-07-24, 9:06 pm |
| no_child_left_unleashed@yahoo.com.sg wrote:
>Noticed that new-in-p
[Wha?]
TO answer your implied question, it would work, but the volumes
required, and the energy requirements to recharge them would be much
higher than a conventional dehumidifier.
Someone does make a regenerative (chemical) dehumidifier, though, but
I've slept since I saw it, so I don't remember much about it.
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| JoeSixPack 2005-07-24, 9:06 pm |
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<William P. N. Smith> wrote in message
news:2ah7e1h15q2jv26q73bmqgb7jh9ba9jiid@4ax.com...
> no_child_left_unleashed@yahoo.com.sg wrote:
> [Wha?]
>
> TO answer your implied question, it would work, but the volumes
> required, and the energy requirements to recharge them would be much
> higher than a conventional dehumidifier.
>
> Someone does make a regenerative (chemical) dehumidifier, though, but
> I've slept since I saw it, so I don't remember much about it.
>
What do you do with all that chemical once it saturates with water? Heat it
up to bake out the water?
The mountains dry out the air by cooling it to below the dewpoint, dropping
it out as rain when it passes over the high ground. If there were some way
to reduce the pressure of the humid air, so that it cools to below the
dewpoint, loses some moisture, them warms back up again, without using much
energy, you'd have the perfect dehumidifier.
Within the realm of science futurism, you could build a giant arch, much
larger than the one in St. Louis, force air in one end, as it rises, it
expands, cools, drops it's moisture, decends, warms again and comes out the
other end as drier air. An artificial mountain so-to-speak.
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| Harry Chickpea 2005-07-24, 9:06 pm |
| William P. N. Smith wrote:
>no_child_left_unleashed@yahoo.com.sg wrote:
>[Wha?]
>
>TO answer your implied question, it would work, but the volumes
>required, and the energy requirements to recharge them would be much
>higher than a conventional dehumidifier.
>
>Someone does make a regenerative (chemical) dehumidifier, though, but
>I've slept since I saw it, so I don't remember much about it.
Calcium Chloride. Interesting stuff. It heats up as it removes the
humidity (absorbs water). (This property is used in a calcium
chloride/sodium chloride road salt mixtures to heat ice and assist in
melting.) It is commonly used in closets or other smallish enclosed
spaces, usually in a bag or container marketed as "DampRid"
Adding more heat will drive the moisture out of the saltwater slush
that forms, but typically the liquid is discarded.
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| Ed Earl Ross 2005-07-24, 9:06 pm |
| William P. N. Smith wrote:
> no_child_left_unleashed@yahoo.com.sg wrote:
>
>
> [Wha?]
>
> TO answer your implied question, it would work, but the volumes
> required, and the energy requirements to recharge them would be much
> higher than a conventional dehumidifier.
>
> Someone does make a regenerative (chemical) dehumidifier, though, but
> I've slept since I saw it, so I don't remember much about it.
Desiccants are used in air conditioning systems for commercial
buildings. The technology is considered too expensive for
residential use.
--
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)
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| nicksanspam@ece.villanova.edu 2005-07-24, 9:06 pm |
| JoeSixPack <olegp@telus.net> wrote:
>What do you do with all that chemical once it saturates with water? Heat it
>up to bake out the water?
Sure. With the sun. A LiCl solution can absorb 10X its weight in water.
Nick
10 A1=12.7409'LiCl vapor pressure constants from the 1993 Hawlader paper
20 A2=-.065536
30 A3=-8.2416E-04
40 B1=-4675.4
50 B2=+29.31
60 B3=+.66911
70 C1=372690!
80 C2=-1689.8
90 C3=-187.1
100 TA=82.8'average ambient August temperature in Miami (F)
110 SG=1770'average August sun on ground in Miami (Btu/ft^2-day)
120 H=12'distillation day length (hours)
130 W=.0176'average ambient August humidity ratio in Miami
140 PV=25.4*29.921/(1+.62198/W)'ambient vapor pressure (mmHg)
150 P=9'dehumidification load (lb H2O/day)
160 FOR TC=60 TO 90 STEP 10'solution temp (C)
170 TK=273.1+TC'solution temp (K)
180 C=A1+B1/TK+C1/TK^2-LOG(PV)/LOG(10)
190 B=A2+B2/TK+C2/TK^2
200 A=A3+B3/TK+C3/TK^2
210 CONC=(-B-SQR(B^2-4*A*C)/(2*A))'equilibrium soln conc (wt%)
220 TF=1.8*TC+32'solution temp (F)
230 CONCSURF=1000*P/(.9*SG-H*(TF-TA))'LiCl surf needed for conc (ft^2)
240 TK=298.1'solution temp (25 C)
250 AP=A1+A2*CONC+A3*CONC^2
260 BP=B1+B2*CONC+B3*CONC^2
270 CP=C1+C2*CONC+C3*CONC^2
280 PVC=10^(AP+BP/TK+CP/(TK^2))'vapor pressure at 25 C (mmHg)
290 PVI=29.921/(1+.62198/.012)'indoor vapor pressure ("Hg)
300 PVL=PVC/25.4'LiCl vapor pressure ("Hg)
310 DRYRATE=.1*(PVI-PVL)'lb/h/ft^2 H2O
320 DRYSURF=P/(12*DRYRATE)'LiCl surface needed to dry P lb H2O in 12 h (ft^2)
330 PRINT TC,CONC,PVC,DRYSURF,CONCSURF
340 NEXT
still solution LiCl Pv drying concentrating
temp (C) conc (wt%) (mmHg) surf (ft^2) surf (ft^2)
60 39.15389 5.493444 21.42437 9.927201
70 45.89019 2.75522 16.3801 13.03215
80 52.33653 1.244954 14.49746 18.96333
90 58.57794 .5091767 13.72873 34.80277
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| no_child_left_unleashed@yahoo.com.sg 2005-07-25, 11:21 am |
| William wrote:
> TO answer your implied question, it would work, but the volumes
> required, and the energy requirements to recharge them would be much
> higher than a conventional dehumidifier.
A room is 8' x 10' with an 8-foot ceiling?
That's 800 cubic feet of volume?
Maximum humidity is seldom more than 0.03 pounds of water vapor per
pound of
air?
A pound of air is 13-1/3 cubic feet, so our room has about 60 pounds
of dry
air. 0.03 x 60 = 1.8 lbs of water vapor.
Silica gel is said to adsorb 40% of it's own weight in water vapor.
Call it
half of that to allow for whatever. so each pound of water vapor
needs 5
lbs of silica. Nine pounds. you think you'll have trouble
carrying that?
It takes 1.8(212-70)= 255.6 BTU to bring the adsorbed water from
70F to 212 F, and then 1800 BTU to evaporate it. 2055.6 BTU
You think you'll have trouble finding 2057 BTU of low-grade heat?
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| no_child_left_unleashed@yahoo.com.sg 2005-07-25, 11:21 am |
| > A room is 8' x 10' with an 8-foot ceiling?
that should read 10' x 10'
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| nicksanspam@ece.villanova.edu 2005-07-25, 3:21 pm |
| <no_child_left_unleashed@yahoo.com.sg> wrote:
>William wrote:
>
> A room is 8' x 10' with an 8-foot ceiling?
>
> That's 800 cubic feet of volume?
>
> Maximum humidity is seldom more than 0.03 pounds of water vapor per
>pound of air?
It's seldom more than 0.02 outdoors in the US... 0.012 is the upper limit
for comfort in the ASHRAE 55-2004 standard (and the int'l equivalent std.)
> A pound of air is 13-1/3 cubic feet, so our room has about 60 pounds
>of dry air. 0.03 x 60 = 1.8 lbs of water vapor.
>
> Silica gel is said to adsorb 40% of it's own weight in water vapor.
>Call it half of that to allow for whatever. so each pound of water vapor
>needs 5 lbs of silica. Nine pounds. you think you'll have trouble
>carrying that?
>
> It takes 1.8(212-70)= 255.6 BTU to bring the adsorbed water from
> 70F to 212 F, and then 1800 BTU to evaporate it. 2055.6 BTU
You will probably find it doesn't need boiling, and 1000 Btu will
evaporate it.
I'd try to evaporate water from a LiCl solar still on the roof during
the day, and let the concentrated LiCl absorb water vapor at night,
so the latent heat doesn't end up in the room.
Nick
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| William P. N. Smith 2005-07-25, 4:21 pm |
| no_child_left_unleashed@yahoo.com.sg wrote:
> That's 800 cubic feet of volume?
Maybe your rooms are 800 cuft, hermetically sealed, uninhabited, and
everything else goes perfectly as delineated by your formulas, in
which case, have at it!
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