Solar air conditioning project and questions

[Psycogeek]

First my Logic

When the Sun is out, that is when the largest quantity of air conditioning is nessisary. (in california, texas , etc)

so

if a solar system that was supplimental (verses grid tie) was able to run some sort of air conditioning, it would be a way to use the power, without the need for batteries as much.

Discount all Swamp coolers for this discussion, swamp cooler is not an option, due to increased humidity, mold mildew, and etc etc . they are highly efficient, and excelent naturality to them (water earth etc).

air conditioning is a very high power consumption device, and impractical for smaller solar systems to try and run say a compressor.

but the compressor on high tonnage devices doesnt nessisarily run the entire time.

i could run a smaller air conditioner

i could run a small refrigerator, and have the coils outside

i could create a huge propane fridge using solar concentrators (see idea i had at half baked)

or

i could run a weird peltier cooling wall.

and that is what i chose to test, because i can test it in the SMALL

the disadvantages of peltier, low efficiency, slow operation

if i look at the low efficiency of it, i also have to analize the low efficiency of a Motor, the compressor system, power generation, and line loss via the power company.  so mabey adding all that in the compressor systems might not be so hot after all.  even if they ARE hot :-)

the peltier ends up pumping 2x as much heat as it draws out

heat exchange with it is 3MM from eachother, unlike with the pipes that can be used in a compressor system to move the exchange further from its source.

the compressors are either whole house, a waste if your not IN the whole house, or much lower efficiency window models. even a window model can use 1500+Watts, and only need to run in cycles.

a peltier system could run as a constant, as soon as the sun to operate it came out.

even though the AC is not needed as much till later in the afternoon.

so i am testing SMALL, very very small, then if the tests have any usefull validity, i would try that larger.  but i am thinking both small and large at the same time :-(  how different it would be at large.

if a house was built with a heatsync WALLs in it, so to speak, it could be designed as a 100% PASSIVE heat pump system.  have enough heatsink, and a LOW enough flow of heat exchange, and there would not NEED to be fans.   Fans are still practical at .9a for a fan, to motivate 9A of exchange, but they still add noise and power consumption.

so a slow running, totally passive peltier exchange system.  got it?

Now with the QUESTION.

is chimmney convection so effective that a OPEN to the air passive heat sync would be cooled more when its in a verticle tunnel?

assume that there is NO wind, just the convection from the heat of JUST the heatsink.

if i put a chimney around a heat sync and its in a computer, that is great, it moves it OUT of the computer, but in this case, the heat is already outside so to speak, and i would just want to increase the passing of heat to the outside.

by Blocking the thing into a chimmney i am reducing exposure , possibly HEATING it instead.  but if convection (heat rising) is so almighty powerfull, would it be possible to enclose or block flow, and actually INCREASE it through convection.

[kww]

What about a modified swamp cooler that cools coils, etc. in which a liquid or gas is pumped through before going to a heat exchanger?   Anyway, to answer your question, I think the chimney would help cool the heat sink better than no chimney, assuming there's no wind.  Paint the chimney flat black above the heat sink for even more convection, spray a fine mist onto or before the heat sink...  

[Psycogeek]

swamp cool the heat sink :-)

water is not an option :-) even if it is more efficient, the owner will not allow it, due to rot, mold mildew etc.

If i paint the chimney black, to increase convection, that would HEAT the chimney, and that would be bad, UNLESS and you may have hit a great point, just the upper part, away from the heatsink cooling area was increased in heat to increase the convection.

but i was not thinking of ADDING more chimney than would shroud the syncs themselves, mabey 8' 9' max chimney, with the syncs ending at 6' max.

mabey them specs dont make enough chimmney?

if it is in a new build house, it must be practical, if its an added shroud , using a bit of wood and a frame, then i can get away with that.

if its a 15' tower, i cannot get away with that.

[kww]

The more chimney the better, to a point, but some chimney is better than no chimney when it comes to convection I think.  

I think you got what I mentioned.  

Here's another idea for you: throw the heat sink in a pond, river, etc.  I know, water.    Still, mold doesn't grow under water, I don't think.  

[nick02]

use water pumped (with a 12v bilge Pump)  to a heat exchanger with a fan blowing on it.  then  use a small compressor to cool the water even more. Then have the cool water pumped through a coil inside your main duct line (or inside the walls of a swamp cooler with copper coils) .

kinda did something like that with a science exparment a long time ago.

[Psycogeek]

water is an extreemly efficient method of motivating the heat and cold off of these electrical peltier things, especially when they have crasy ones like 370W.

the efficiency of the peltier changes quite a bit if you remove the exchange off of both sides.

but add in a pump, just like in the computer water systems, you add in a motor (that can fail) , and pressurized water garbage. and hoses and and and.

even a very small aquarium pump would move quite a volume of water.

but if the pump failed, so to would the whole system, i could even fry the solid state components , just like they fry computer processors, and spray stankey water all over thier computer :-)

i have seen the inside of a computer water block after time, even with proper maintance, its loosing conductivity in about 2 years.

look at a poorly maintained swamp cooler, Green from algie and moss hard water, stuff growing on it, stuff living in it. proper maintance of them means replacing the water plates, and eventually replacing the fan

with passive running very Low slow, not thermostatically controlled like we usually think.  

 I am cold , 22,000BTU and 5 minutes later everything is fine.

i forgot to mention, that peltier can be reversed, so you can heat more efficientally (with electricity) than resistive loads like baseboard heaters.

by just reversing the current flow, the cooler becomes a heater, not as often that solar would be used to run it, but some.

Just like baseboard heaters, is how i would like to see the system work, big arse heat cold transfer capacity, at low volume, much lower than baseboards or central systems, for a continual time.  baseboards are very low maintance, and long life.

low volume means ease of solar load, without specific voltage devices, no conversions or regulation is nessisary.

a Peltier specked for 12V could run at 10, or 14 just about as efficientally, a motor would be less likely to adapt to any voltage tossed at it, from unregulated sources (made by psycos :-)

also these things could be used in dueality instead of reversable , use both sides, heat your food on the other side of the refrigerator.

Ground or Pool, or pond or creek conduction would improve the efficiency greatly

sending the cold water to the house, and the hot water to the pool, would be excelent.  but again there is hoses everywhere, pumps, more STUFF. water corrosion etc.

the idea would be a 1 TIME cost, and magical operation after that.

30 years to pay for , then retire :-)

[domwild]

Adding my two cents worth: Mosques are cooled in this way: Hot desert wind is drawn into the tower the muezzin shouts his prayers from. The air gets piped down the tower and under the basin the faithful wash themselves, I suppose this is your swamp cooler. The cooled air then enters the mosque at the bottom and rises through the hole at the sperical top.

As you do not want a tower next to your house, you can use a blower. Take the air in concrete pipes through some wet earth and you get the cooling effect. Getting a fat pipe into the living area of the house could be a problem.

*

[scottsAI]

3.4 BTU's in a watt/hour

I have a 2.5 ton AC, 2.5*12,000= 30,000 BTU. In Michigan 1400sqft.

30,000 / 3.4 = 8,823 watts.

Assuming 2x = 16,000 watts.

The largest peltier I can find is 63 watts.

16,000 / 63 w = 254 peltier.

Lowest price is $18.

254 * 18 = $4,571.

I paid $1600 for my AC, 10yr ago. Current price is about $2K.

You must have a huge solar array to consider powering this form of AC.

I used your numbers, but the reality is for each deg delta temp the eff

of the peltier goes down. With 40 deg delta, you will get about 10 watts

of heat transfered, with 63w in. Look at the heat in to out curves.

I have studied this problem. The best solution I have found is Geo thermo.

If you have a source of cool water the efficiency of the heat pump goes

way up. I attempted to calculate: looked to be 5-6x better than air exchange AC.

Depends on how cold the water is.

Using cool water without heat pump does not work, the air's humidity stays high, you have to cool further to have the same effect. With a slight breeze from the forced air, makes you cold. Running a dehumidifier with it draws almost as much power as the AC!

My compressor draws 3,010 watts running. The blower 400w.

With Geo thermo, a smaller unit could be used, offering significant power savings.

There are high eff blowers now available. costly, but when solar cost

$6/w then are cheap.

Nice thing about a heat pump; they heat, and can provide hot water.

Have fun.

[Psycogeek]

ahh there you go with all that nasty math and science :-)

were running a 3 or 3.4Ton system here, just the fan is probably 300+Watts :-(

the lights dim when the compressor turns on, it has a 45 AMP fuse (i guess they had a hard time finding a breaker that BIG.

and it like most compressors Hard starts, so mabey it only uses 1500+ watts to run the worthless contraption, but it probably uses 3000 to kick in.

the power meter looks like its playing a 45rpm record :-)

so i agree with all of your assesments , its a huge load any way you look at it.

but, you missed the point of continual solid state vrses cycling compressors.

what if the present even 3.4T system we have, which is about 1seer rating :-) and costs 5000$ to even try and upgrade it to a 13-14, and already is 100% out of spec, based on the length of pipes used.

was only operated 1/10th or 1/25th of the time in cycles?

doesnt it have bad delta factors, when you cant get the heat off the condencer coils

or when the expander coils instantally freeze water on them, and reduce the efficiency.

do we have the total specs on the waste that a compressor system is? they even put the compressor which gets very hot, in the middle of the coils that is trying to be cooled.

now tack on the 300-500W fan that is on the outside coils, and the thing is a BEAST, its very efficient mabey, but it would never run off of solar.

You see the peltier system could be on a continum. run non-stop, run when the sun is out.  it is highly inneficient, but so to is the other. and it cant be reversed.

the peltiers would be rediculous to use as a central cooling system, again we agree.

the CLAIM for the average peltier is a 50-85W heat transfer, i can get them for only 10$.

somone claims to have a 370W but i dont know if that is the quantity of motivation, or the total power consumption, or just the HEAT output on one side :-)

it would also be very hard to pipe off of it efficientally all that kinda juice, but the cost is less than 30$ for one of them.

and i could use a multiple of these in a properly designed house.

the cost of the peltiers to get say 1500W would be no big deal, the cost of the heat transfer would be more than the peltiers,  huge sinks, or water motivational systems.

taking your Efficiency at the low delta into concideration, and figuring on WHEN it would be used, with the external heat at 100* removing the heat would be terrible.

without water cooling at least the exterior side when trying to cool the interior.

so i guess that means it would HAVE TO, have a water system, i could run pipes underground at 1 foot under the ground, they say its about 60*, so that would make a HUGE delta difference.

so that changes that , now i am stuck with a mess of pipe trash.

might as well, take the 60* water, and just pipe that straight in, it would be as good as a PASSIVE sync system, that would be run slow, and basically be putting out 50-60* air anyways.

[Psycogeek]

when it comes to HEAT, i am happy sitting in front of a 500W light.

if i can move 500W using 1000W , and get 1500W of heat , i would be quite happy.

if that is 10 370w peltiers running at 150 watts, that would be ok heat.

Reverse that

If 500W of motivation is that effective

then 30 peltiers moving 1000W of cool (and 3000w of heat outside) would be sufficient for a window air conditioner.

so that would mean a 2K solar system.

but try and run that window AC i got off of that, its 1500-1700W Same difference.

[Kwazai]

I lack the money to pursue it, but what about adapting an RV propane refrigerator to run from a dish? ammonia cycle refrigeration- lot of pipe involved. I would figure one modified fridge would make a window unit size airconditioner. just my .02$.

Mike

http://www.motherearthnews.com/arc/4514/

[scottsAI]

I looked into using just the cool water for AC.

The pipes need to be down 6 feet to 10 feet, to get the cool

temperatures. (depends on where you are, soil etc.)

The problem with the passive system, is it does not remove the humidity.

To get the comfort you desire. In Mi, the humidity gets 90%+, you can

cool down to 70 deg and it still feels yucky. To run a dehumidifier cost

almost the same as AC. The humidifier adds heat!

If you have the cool water the heat pump can be very small.

Since I have not built it to verify... The eff. of 5x should translate

to 3000/5 = 600 watts, the blower now at 400w with a new blower should

be down at 300w. So, based on data from real systems I should be able to

upgrade to a 900 watt heat pump system. I would use it for heating also. The

temp difference is much greater. The heating side would determine the

size of my system. I have seen -23'F for 5 days. Very coold!

The size of an AC system is based on the worst temperature in the area.

Mine kept the house cool when it was 107 deg outside. Ran 23.5hr that

day. Almost at it's limit. Above 100 is uncommon.

If you design a system to run all the time, when it gets hotter than

normal it will not be able to deal with it.

A normal hot summer day is 95, so would have been 92 inside on the 107

day. Not very cool.

Have fun.

[pyrocasto]

I think I'm going to use some 350watt peltiers on ebay for a dumb load when I build my wind genny. I hope it will work fine as a small AC and warm in the winter, but I dont know if I just want to use a fan and heat sink or water, radiator, and a fan to move the temps.

[Psycogeek]

see my crasy idea for a solar refigeration here

http://www.halfbakery.com/idea/Solar_20AC#999622800

my idea is along the lines of , moving the fluid by concentrated sun, when you hit these volitile liquids with Heat, they get active fast, much faster than water.

a steam system might be practical for a huge concentrator, but moving ammonia, or freon , or something would be easier with lower temps from a small collection.

also the idea of having the tracking done with a quad of freon hydrolic chambers, that get heated when the concentrated sun is in the wrong location.

its similar to a propane fridge.

but nobody could tell me how to Cycle it, or checkball it, or how to get the "fluid dynamics" to work in a way i can figure it out.

again this one is OUT because the owner wont have it.

[Psycogeek]

I was figuring a LOT of heat sync with 370, even running it slow, but using the extra SIZE of it to have better distribution on the sync

i think like this, a processor heat sync has to move about 80W , most the time less than that with HLT cooling .  so per computer heat sync i figure 40W to get good transfers.

with 370, assuming you could get the battery cables big enough to get that at it :-) it would take would have to have a sink that is 10x more capable than a processor sink.

of course OLD processor sinks are CHEAP and can be purchaced cheap with copper bases, and aluminum fins, or all copper.

[Psycogeek]

"pipes need to be down 6 feet to 10 feet,"

Backhoe time :-(  impracticality, difficult to repair.

a de-humidifyer, is just an AC unit anyways, total waste, most of the dehumidifyers just put the heat right back into the room, even though they "heat pumped" to get the condensation.

this little peltier TEST i am doing at 15Wx2 is barely cool, and the hot side is rediculously hot.

even though it is passive , and therfore VERY SLOW, and has adequite sink for distribution of the cold side, water is condencing on it very rapidly.

i think with a whole system, i would get a gallon a day.

i dont live in excessive humidity place, i was thinking with a slow enough transfer, condensation would not occur, but its here and that is VERY slow.

[Psycogeek]

Also , i was reading that the peltiers can get Damaged.

just so you know, from all the stuff i read, if you let it get hugely hot, or hugely cold on either side any way you do it, it could be permenentally damaged, even if it still works good.

so not just heat damaging the high temp solder points, but expansion and contraction damage aparentally.

the specs for them show sink clamping possible at 10X a processor sink clamping.

so if you plunk down your change, be sure to protect it even when testing.

i was surprised the ammount of transfer from the ceramics, usually cermaics are poor conductors.

[scottsAI]

I think you might like:

http://www.advancedbuildings.org/main_t_heat_gasfired_chiller.htm

Building uses gas to cool with.

The gas produces heat, you could replace it with solar heat for AC.

I have seen a lithium bromide chiller in operation. Worked great.

The final cooling stage was the evaporation of water in the cooling

tower. At the time the claim for Li-Br chillers was a BTU of gas is 1/3

cost of electricity. The cooling tower size was reduced by using

evaporation.

BTU for BUT the Li-Br was as efficient as the R12 machines. (now R134a).

If any of the above is true, then replacing the gas with solar you what

what you desire. Needs 100'c to 175'c temps.

Check out:

http://www.redrok.com/wellsrussell.htm

Dave explains this all better than I can.

Have fun.

[Psycogeek]

ohoh , brain fry :-)

he is using so many brand names and abreviations its hard to understand any of it.

i didnt hear him say Home Depot , or Pic-U-Part once :-)

looks like he is getting power from the gas expansion???

YES, it seems easy to use collectors or concentrators to achieve 175* assuming he wasnt talking celcius.

thse sysetem are so BEEG.

Water-based radiant panels cover 30% of ceiling area; panels operate at 35°C in winter and at 13°C in summer.

oh sure, cover 30% of the ceiling, i couldnt even afford the re-distribution system of the cool water.

they probably are using exchangers, ect.

to complicate it like that, requires a goverment grant :-)

oh thanks for the link, i will go get a PHD and get back to it.

[Psycogeek]

That was GOOD, i actually understand that stuff.

Dale :-) crasy man with the wood fired fridge.

i can see how i could create a small testing using that type of logic.

the Requirement of the gravity flow is a bit of a problem.

the condencer (the part you have to cool)

and the liquid reciever (the part that holds the fluid)

have to be above

the expander ( the part in the house that cools)

it means cooling would have to be on top of the house, and the resivor too.  to get the expanders below that.

and therin lies some of the impracticality, to cool the condencer to get a Very very COLD expaner, would mean lots of passive cooling on top of the house, where the sun is,  or back to the ol Pumps again. where you could bury the condencer, as long as you pump back to the resivor. the pump deafeats the whole purpose.

EX: mom says that propane refridgerators in motoe homes during extreeme temperatures 100+F have trouble keeping ice cream hard , ice cream because of fat content, has to be Below normal freezing temperatures.

without being able to cool the condencers during High temperatures. the expaners are not going to be FREEZING cold, and the size of the system then becomes stupid.

if you go back to a pump, then you might as well Pump freon.

i understand cooling through gas expansion, and motivation of gasses with heat, but i still do not comprehend what they mean by "absorption" and other terms.

isnt this thing

 just expanding gasses to defy gravity,

 cooling the expanded gases (you just heated)

 jetting the gasses into an expander

what is the absorbtion?  the amonia wants to get back to the water

ya sure, ammonia loves to get back with water, i seen it crawling out of the windex bottle last week :-)

[Psycogeek]

Wow we did it again, get to much brain going, and the topic drifts off , and the original question is 100% lost into oblivion

WHAT about the CHIMMNEY ?

the original question,

Will a shroud provide better cooling through convection

a chimney around the heat sinks

OR

Will a shroud mess up the cooling by covering

and reducing exposure to the rest of the air

KWM commented on it, do you all concurr?

[Kwazai]

http://techref.massmind.org/techref/other/spac.htm

this is the basis of what you are thinking- a few good references there. I am assuming that you had looked at the heat sink equations from computer stuff (finned aluminum). If you had a condenser coil stuck in a chimney  and sufficient convection from the chimney-there is a good possibility it would work. I thought about burying a condenser under my house(crawlspace) and running water through it-based on the electronic heatsink calcs and realized somehwere in the neighborhood of 300sqft would be needed to accomplish 'air conditioning' with geothermal crawlspace 'heatsinks' (1200sqft house). If the chimney you would use would pull the cool crawlspace air (deltaT=20F or so) the convective cooling might actually take a little less surface area- chimney would probably be standard house size with the heat supplied to run it from the attic- (tee fitting type venturi pump duct work?). problem would be getting pressure drop across the condensers with cool air.

I have more links if you would want to pursue it- didn't seem practical at the chimney and would take somewhere around 300sqft as a geothermal crawl space heat sink. Not sure how long buried aluminum would last in the soil.

Peltier heat sinks I thought were electrically based-- temperature follows the direction of the current...

[Phil Timmons]

Have pondered this more than a little bit myself around here (here being Texas) where there is some serious heat.  But I am also familiar with Michigan (that was home a lifetime ago) and yeah, you have some SERIOUS humidity and "air drying" to handle before you even think about cooling the air.  Usually a cooling coil in the near freezing range (35 degree (F)) tends to do that well.  Same way a de-humidifier (without cooling) tends to operate.

That leaves you with evaporator coil temps that freon systems tend to handle well -- I will not say "best" yet, but when you consider the mass manufactuered availability of freon based units -- even window units, they are relatively cheap and easy to work with.  

Have played with and owned some of the available "gas fired" ammonia / water systems.  I had a few old ones sitting around and started kludging some together -- where I went with that was that while you could reasonably heat the water mixture with solar instead of natural gas, playing with homebrew ammonia in a residential setting, I considered an unacceptable risk.  Also, the cooling coils tend to operate much warmer (around 50 degrees, F) so that means they are not so good on drying your Great Lakes' 1000% humidity.

Part that I like of your concepts, so far, are the "natural" design of the structures you are considering.  That brings up something a bit tired and while it is a bit retro -- insulation and underground construction make a huge difference on the size of the task you are pursuing.  

Anyway, where I wound up heading -- design-wise -- is towards directly making electricity in serious quantity, and just running conventional air-conditioning.  Cheap, quick, easy to replace/repair.  Just expensive to operate conventionally.  So the issue went away from Solar Air Conditioning towards serious Solar Electric.

The rig I am building for that now is a Solar Boiler system, with turbine and generator, all made from surplus/junk parts, but my goal is that it be easily replicated by Joe Anybody/Anywhere.  I have some interest in the "Tesla (yeah, I know ) Turbine Builders" folks in the UP (upper peninsula) up there.  I read were they are mentioned on this site.  I may visit for their one week of Summer, in July.

Well, this note got a bit long, but it looked like you were walking around some paths similar to the ones I walked and just was going to mention where I wound up with it all.

Good Luck, sir, and I will keep looking over your shoulder, if you do not mind.

[Psycogeek]

Also, the cooling coils tend to operate much warmer (around 50 degrees, F)

yes :-(  need more freezing, not just to increase condensation, but because it ends up being a rediculous ammount of evaporator coil, or sink, or transfer on the interior.

especially if they do a exchanger, and run cold water in, not going to cut it.

to many losses along the way and all.

but what IF the condencer was cooled to ground temps 70*F ?

  can the expanding ammonia type gasses get cold?

or is it just not volitile enough like freons.  

[Psycogeek]

didnt get the link to work yet.

that is a good idea, i had not thought about getting the convection chimmney air started from the ground under the house, its always a bit cooler under there.

but i am not sure if it will be SLAB or foundation. because slab alone already keeps the house cooler.  got slab here so cant test that without running the chimney across a area of the ground. that increases the "shroud" size by large horizontal ammounts.

[Phil Timmons]

I have to give you a design level "I do not know" to that part.  

I am certain that ammonia designed systems have the capacity to get very cold.  I think the big commercial ice plants and cold storage plants around here (Dallas) use them -- in fact I have worked on parts of the controls for one, but the ammonia end of industrial processes like that are considered hazardous.  Hazardous and homebrew can be a very, very bad combination.  

The 50 degree (F) designed cooling coil(s) I was talking about were natural gas residential ones I salvaged and played with.  I would think they could have conceivably been driven colder, but that was the design operating point.  I am not sure why they were not designed to run colder.  It may have been an ammonia concentration and pressure (and residential safety) issue.  What I was messing with was using solar heat for the outdoor part.   And even those ones could be pretty unpleasant with a leak.

For my bias I had smelled enough ammonia farming back up in Michigan a lifetime ago.

I suppose if one wanted, you could use heat to run a freon system, as well -- in place of the compressor.  Dunno, had not pondered that before.  

[Kwazai]

back to the original question--

some of the old stuff I had seen on hydronic air conditioning put a cooling coil close to the ceiling, just off the wall (they had problems with moisture condensing on the walls. Assuming you had a peltier "coil" close to ceiling at the outside of the room- the chimney draught could go thru the ceiling or above the ceiling with the cool side inside the room and natural draught cooling- moisture condensation again as if hydronic radiant cooling. From what I've been able to tell- people bailed for the most part on this type of cooling because of the moisture problem. Most of the systems had a drain pan under the cooling coil. From the prices you had memntioned- one room would make an ideal test bed. not sure about the numbers though- 1500W worth maybe for a room??

[Psycogeek]

yup

and i was planning on collecting the water with a tray type thing below it, that would send the water back outside.

the present AC uses that method.

and a TEST would have to be in a Window giving me about 2x4' of total space.  which sounds like a fan requirement.

the 3MM gap between the little THIN suckers is a big problem, insulating between them would have to be done for anything other than a test.

they have awesome passive copper plate, copper heat pipe aluminum fin , processor sinks now that are designed for passive.

this design would get the exchange AWAY from the 3MM thing, and PAST a insulation.

but they cost $30+ each Still.

with that type of sync, i can insulate around each peltier.

[Psycogeek]

here are the (to high priced) pipe coolers

http://www.quietpcusa.com/acb/showdetl.cfm?&DID=8&Product_ID=208&CATID=3

http://www.frozencpu.com/images/products/detail_hires/cpu-sls-01.jpg

http://www.silentpcreview.com/article201-page1.html

see how the Basics of these designs, can MOVE the heat and cold, from the tiny and thin peltier, into the area for dispersion of the exchange.

by doing that, more insulation between, and more passive capacity, more movement off the 3mm for dispersion.

[Kwazai]

If I can find it, I have an old bookmark page that has some links to just the base units(peltier). I had been looking at them in terms of cooling some circuitry for a fuel injection system. The basic Peltier devices were more like just a large microchip and did not include the coil,etc. of the cpu coolers- one side hot, one side cold. The cpucoolers look like they would be relatively easy to configure for PV cell usage, though. not sure what the diff. in efficiency would be. I will look for the bookmark page over the weekend and post it if I find it.

[Psycogeek]

Phhhhhtttt :-P

darn, i am testing that peltier off of e-bay, and , ,  err

well its either going to need water cooling, or a sink the size of manhatten

i had some really GOOD efficiency with the 2 small 5V ones

had one side freezing, while the other side was blowing some heat.

using 2 copper base, aluminum fin sinks.

Everything was all peachey and keen

but this THING is just a Heater :-P

i put it in the Same contraption of sinks

i have even ramped it down to a relative speed that the 2 little ones went,

and it still doesnt do diddley.

mabey i damaged it already.

if this is efficiency, mabey it will make a good STOVE.

[Kwazai]

sure its not hooked up backwards- they are DC devices.

[Kwazai]

adsorption- at a specific molar concentration a particular temperature and pressure 'coerce' (for lack of a better word)- the gas(nh3) back into the water (nh4oh). Most of the adsorption clacs are related to the wetted surface area -sort of like the reverse of boiling,with the 'inverse boiling point' (again for lack of a better word) being temperature and pressure dependent because of the concentration (off the shelf 26baume aqueous ammonia is roughly 17%(?) by volume nh4oh- not a chemistry expert here...). A first year college chemistry textbook probably has the best explanation of it- my ME textbooks were even less help.

ammonia gas liquifies somewhere around -28F at standard atmospheric pressure.

a mixture (aqueous ammonia) works the same way antifreez does- in that the boiling/freezing/liquefaction points change based on concentration. hence adsorption-ammonia gas going back into liquid solution (pressure-temperature and molal concentration-wetted surface area dependent. I'd have to look up the exact equations- the ones I had seen were all based on partial pressures of gaseous mixtures.......

Mike