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easy, DIY solar powered AC for small room??

P

P E Schoen

Jan 1, 1970
0
Here are 60W Peltier cooling plates for $4 each with free shipping. 200
BTU/hr. 25 of them would (should) give you a 5000 BTU/hr A/C for under $100.
http://www.ebay.com/itm/320899431129
"Watt" a deal! How do they do it?

These are more believable (and complete units with heat sinks). $38 each for
70W or 170 BTU/hr. They are selling 24 pieces for $35/each. So for $840 you
would have a nice 4000 BTU/hr A/C. I don't know the efficiency, but it's
probably a lot better than going through a solar power inverter and then an
AC motor and compressor.
http://www.mpja.com/Peltier-Cooling-Assembly-Larger/productinfo/15513+PM/

Paul
 
A

amdx

Jan 1, 1970
0
amdx pretended :

Developed as early as 1890 in Coolgardie Western australia. See

http://en.wikipedia.org/wiki/Coolgardie_safe

Works much better in a breeze and is only impeded by sunlight which
provides the heat that, in truth, should be drawn from the contents

I'm curious if this concept could be pushed further, with modern
material and technology. Just to throw out an idea, a very well
insulated room with a pipe running in the center of the room vertically
to the ceiling, then horizontally to the outside down to the ground then
back to the center of the room. Circulate a liquid through the pipe. On
the outside the pipes use the evaporation concept to cool the liquid
which circulates to the center of the room. The pipe/evaporation
scheme would be duplicated as many times as required for the room.
I wonder if the liquid could be self circulating just by temperature
difference alone. Are there materials that could be used for the
evaporative sheets that are more efficient.
In the end it's a swamp cooler, but we don't want the evaporated
moister inside the room, we do want the cooled liquid
in the pipe circulated into the room.
Your ideas welcome.
Mikek
 
M

mike

Jan 1, 1970
0
I'm curious if this concept could be pushed further, with modern
material and technology. Just to throw out an idea, a very well
insulated room with a pipe running in the center of the room vertically
to the ceiling, then horizontally to the outside down to the ground then
back to the center of the room. Circulate a liquid through the pipe. On
the outside the pipes use the evaporation concept to cool the liquid
which circulates to the center of the room. The pipe/evaporation
scheme would be duplicated as many times as required for the room.
I wonder if the liquid could be self circulating just by temperature
difference alone. Are there materials that could be used for the
evaporative sheets that are more efficient.
In the end it's a swamp cooler, but we don't want the evaporated moister
inside the room, we do want the cooled liquid
in the pipe circulated into the room.
Your ideas welcome.
Mikek
Dias Analytic
https://www.google.com/search?num=1....0.0.0.182.182.0j1.1.0...0.0...1c.boGF2uLShRo

has a process that uses a membrane to suck moisture out of the air
without condensing
it or changing the temperature. Then they put the air thru a swamp
cooler to
cool the air and put the moisture back.
A year ago, they had the DoE interested enough to give them a bunch of $$$$.
But the steady decline in stock price suggests that things may not have gone
so well since.

If you have a hot area and a cold area, you can move the heat from one
area toward the other.
Normal technology requires some kind of heat exchanger.
The problem is that the hot area is typically higher in elevation
than the cold area. Efficient heat exchangers, like heat pipes,
work better moving heat upward. That requires some motive power
to reverse that process.

I've made some heat exchangers for a heat recovery ventilator using
copper pipe and freon. The pipes work amazingly well. Problem
is getting the heat from the air into the pipe with stuff you can build
in your garage. Suggestions welcome.

For air to air exchange, DIY units made out of Coroplast give a lot
of bang for the buck. Would be interesting to try to make an air to
water one.
Would take a LOT of caulk to patch up all the leaks. Or just use a car
radiator.

Bottom line is that your best investment is insulation. If you have
EXCELLENT insulation, simple schemes like pumping water around have
a better chance of working, but the amount you save is small.
Do the math. Takes a LOT of water to mediate the daily temperature
change, even if you do have the right climate for it.

If you do the math, it's likely that anything you do with retail cost
parts isn't cost effective. It then becomes a hobby exercise in what
you can do with what you have on hand or available for free.
 
M

mike

Jan 1, 1970
0
Here are 60W Peltier cooling plates for $4 each with free shipping. 200
BTU/hr. 25 of them would (should) give you a 5000 BTU/hr A/C for under
$100.
http://www.ebay.com/itm/320899431129
"Watt" a deal! How do they do it?

These are more believable (and complete units with heat sinks). $38 each
for 70W or 170 BTU/hr. They are selling 24 pieces for $35/each. So for
$840 you would have a nice 4000 BTU/hr A/C. I don't know the efficiency,
but it's probably a lot better than going through a solar power inverter
and then an AC motor and compressor.
http://www.mpja.com/Peltier-Cooling-Assembly-Larger/productinfo/15513+PM/

Paul
The problem has two loosely coupled parts, so let's separate them.

1)How do I cool the bedroom?
If you need to move heat from one place to a hotter place,
it's hard to imagine anything more cost effective than the air
conditioner he already has. Peltier is a very bad solution for
anything without severe restrictions...like cooling something
that puts out no power to very cold temperatures...thermal imaging...
or something that can't have any moving parts. Yes, sometimes it's
handy to be able to drink warm pop in the car instead of hot pop,
but it ain't efficient.

If you have a heat sink at a colder temperature, you may be able
to do something with a heat exchanger.

2)How do I power it cost-effectively with solar?
You don't!
 
P

P E Schoen

Jan 1, 1970
0
"Jeff Liebermann" wrote in message
Well, it might be expensive to air condition the entire room, but
he could build a space suit, and pump chilled water through vinyl
hoses between himself and the space suit. Cool the user, not the
house.

There are personal cooling vests and suits:
http://www.veskimo.com/liquid-cooled-microclimate-vest.html
http://en.wikipedia.org/wiki/Liquid_Cooling_and_Ventilation_Garment

You could probably make chilled water and circulate it through tubing and
thermally conductive pads placed on various parts of the body to feel
cooler. Sort of the reverse of a diving heater:
http://www.patcoinc.com/aqua_heaters.html

Paul
 
M

Martin Brown

Jan 1, 1970
0
2)How do I power it cost-effectively with solar?
You don't!

And that is even true for off grid provided that there is some
relatively easy way to carry a suitable battery to and from the site.

Wind turbines are a little bit better - you might at least hope to get
enough electricity out of one of them on a good day to power A/C though
there is still a very hefty capital investment to do so.

Best you can do for a small room is put a scacrificial thin shade layer
on the sun facing walls and follow the sorts of ancient building codes
with verandas and shutters to keep heat out during the day. Cacti and
termite mounds demonstrate most of the requisite engineering tricks.

Using modern advanced insulating materials like aluminium foil backed
bubble wrap and the equivalent in thick glass fibre insulation you can
prevent a lot of heat getting in from the roof space. Preventing the
heat getting inside is better than struggling to remove it later.

Regards,
Martin Brown
 
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