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Solid state AC

T

TheoPetro

Banned
Im moving to a new dorm in Aug.

This new dorm has NO AC! I sweat like crazy when I move much at all even in AC. I dont want to imagine whats gonna happen if there isnt any.

I had the idea to buy a few TEC coolers and vent the hot side outside while circulating the air in the room across the cool side. I could vary the temp by changing the wattage put into them. The room is ~12x15x8ft. It gets ~85 here.

How many 226W pelters/ how much air flow will it take to keep this room a comfortable 70deg.

Power usage isnt much of a concern but I would like to try and not trip every breaker in the place. This shouldnt be too much of a problem (I dont think) because I have a room to myself that is orig made for 2 people so it was wired for 2 people as well. We cant have AC units because of the power draw but I doubt my home made one will hurt too much.

My other reason for this little project is to keep my newly aquired 7900GTXs from burning up if I want to play a game during the day. They get ~70 while playing in my room that has AC.

Any help would be really appreciated. Especially concerning where I can get really inexpencive powersupplies for this or pelters.

Thanks

Edit for cliffs:

Cliffs:
Want to cool a ~85deg room w/ pelters.
Power isnt an issue.
Room is ~12x15x8ft
 
Firstly, the ammount of power needed to cool a room would be huge. So this would certainly consume more power then a window AC unit. But, what about a water bong? As long as the room is 25% humidity or less, you could use a makeshit swamp cooler to cool the room. Just set up a large capacity water bong, and instead of using the water to cool a CPU, just circulate it through the room.
 
Realize that if it were possible to make an air conditioning unit that would cool a room while using much less energy, they would already do so. However, it seems to me that there are some smaller AC units that only draw 6 or 8 amps. Thus, you may have a chance at doing something successfully.
 
Well, you'll need about 4 kW of cooling for a room that size. Additionally, your Peltier will need to generate about 30-40 C of temperature difference. (You want to the output side about 5-10 C, and the output side will need heatsinking capable of being cooled in a 35 C environment).

So. Let's assume that Peltier devices can operate at 50% of their Qmax in this situation. The above devices will be able to provide about 110 W of cooling each. So, you will need about 35 of these devices to acheive adequate cooling.

Seriously, in case you hadn't worked out - Peltiers are pretty much useless for cooling anything except the smallest things (e.g. CPUs). They are huge energy hogs, and have poor cooling performance.

A proper AC unit would be about 1/6 the price of building something out of peltiers and fans, and use about 1/6 the power.
 
Power isn't an issue, but a window AC uses too much power? As Dr. Pizza stated, if it was possible to do this using less power than a normal AC, it would already be on the market.
 


Yep, my roomates' coleman cooler ( can hold ~2-3 six packs ) had enough trouble keeping a few cans 'cool' - It had a 72W peltier I believe with a single fan driving a fan on the cooling side and the heated side.

Even if you did this, how would you eliminate the heat? I would guess for best performance a BIG ASS heatsink would be needed on the heated side sticking out the window with maybe a fan to help move the air. It's just not worth it.
 
~sigh.

I was hopen this one would have worked. The reason I cant get a normal AC unit is because there not allowed. If I had something that I could say was for my computer I think I could talk em into letting it slide if it ever came up.

Im thinken a massive dehumidifier + that bong cooler (if the bong cooler idea would work to cool the room) I cant remove the screen on the wondow ( and there not a normal size) but I can throw somethen together out of plexi or cardboard+ducttape and a fan to expel the heat from the room.

Any info on the bong cooler?
 
Originally posted by: TheoPetro
~sigh.

I was hopen this one would have worked. The reason I cant get a normal AC unit is because there not allowed. If I had something that I could say was for my computer I think I could talk em into letting it slide if it ever came up.

Im thinken a massive dehumidifier + that bong cooler (if the bong cooler idea would work to cool the room) I cant remove the screen on the wondow ( and there not a normal size) but I can throw somethen together out of plexi or cardboard+ducttape and a fan to expel the heat from the room.

Any info on the bong cooler?
Click to expand...

Google FTW. Try XtremeSystems also. I was thinking it would work cause, as you said, it would be convincingly like a computer cooler.
 
Howbout just roughing it like everyone else did in college? My dorm didn't have AC and I don't recall anyone having problems. Just get a big stand fan or something and keep the air moving.

Do you have some medical condition? If so, the school will probably accomodate you with an AC'ed dorm.
 
Originally posted by: sjwaste
Howbout just roughing it like everyone else did in college? My dorm didn't have AC and I don't recall anyone having problems. Just get a big stand fan or something and keep the air moving.
Click to expand...

Seriously, my freshman dorm had no AC and I just bought a high-airflow fan at Sam's for a couple of bucks and sat it next to the window. A few people with bigger rooms used 2 fans (in parallel, or for one to serve as exhaust) and had no problems even with 2-3 computers running 24/7.
 
Originally posted by: JohnCU
AGAIN, WTF kind of dorm doesn't have AC?
Click to expand...

A lot of them. I think about half of the dorms on my campus do not have AC. It is not as big of an issue as one would think due to the fact that you are really only on campus for about 2 months when you would need them.
 
Originally posted by: Born2bwire
Originally posted by: JohnCU
AGAIN, WTF kind of dorm doesn't have AC?
Click to expand...

A lot of them. I think about half of the dorms on my campus do not have AC. It is not as big of an issue as one would think due to the fact that you are really only on campus for about 2 months when you would need them.
Click to expand...

Depends on where you live, doesn't it? Here, I run my AC 11.5 months of the year.
 
2 things to keep it cool from an experienced dorm person.

1.) Buy 2 large 'tornado' floor fans from Home Depot or Lowe's they'll probably be about 36-40 inches in diameter. Place one as an exhaust fan in the window. PLace the second in an opposite corner pointing towards the other one. The idea is to move air at all times.

2.) Buy a dehumidifier and run it constantly.

If you do those two things while keeping your door shut and the shades drawn during the day, your room will stay about 10-20 degrees cooler and your PC wont suffer either.
 
Originally posted by: JohnCU
AGAIN, WTF kind of dorm doesn't have AC?
Click to expand...

A lot don't since ACs would cost the schools money to retrofit older buildings and increase operating costs. Also, ACs are only neeed for a month or two for many schools, so it is a useless investment for them.
 
Originally posted by: DeathBUA
2 things to keep it cool from an experienced dorm person.

1.) Buy 2 large 'tornado' floor fans from Home Depot or Lowe's they'll probably be about 36-40 inches in diameter. Place one as an exhaust fan in the window. PLace the second in an opposite corner pointing towards the other one. The idea is to move air at all times.
Click to expand...

How big are dorm rooms now? I could have barely fit a 36-40 inch fan through the door let alone have any room to actually keep it running in my dorm room. No AC by the way but the hottest it ever got was only about 106F. Was time to go down to the river and go tubing!

 
its kinda tough to set up but since he'll be living by himself it'll be easier my dorm room if IIRC was 15x 13 without a bathroom
 
Thermoelectric cooling would be considerably more expensive than the phase-change systems commonly in use in refrigerators, air conditioners, and dehumidifiers - the compressor setup and all.

Power usage isnt much of a concern but I would like to try and not trip every breaker in the place. This shouldnt be too much of a problem (I dont think) because I have a room to myself that is orig made for 2 people so it was wired for 2 people as well. We cant have AC units because of the power draw but I doubt my home made one will hurt too much.
Click to expand...
Power draw? A new AC shouldn't take more than maybe 6 amps for a small ~5200 BTU unit. That'd be somewhere around 760W.
You're talking about 226W Peltiers? And how many of these do you plan to use? How do you plan to supply them power cheaply? High-amperage 12VDC power supplies aren't what I'd call cheap.

Realize that if it were possible to make an air conditioning unit that would cool a room while using much less energy, they would already do so. However, it seems to me that there are some smaller AC units that only draw 6 or 8 amps. Thus, you may have a chance at doing something successfully.
Click to expand...
Agreed. I've seen peltiers used one place to "replace" compressors: in a tiny closet dehumidifier. And it's $45.

Originally posted by: sjwaste
Howbout just roughing it like everyone else did in college? My dorm didn't have AC and I don't recall anyone having problems. Just get a big stand fan or something and keep the air moving.

Do you have some medical condition? If so, the school will probably accomodate you with an AC'ed dorm.
Click to expand...
That's what I had to do in a dorm during my first semester. It got close to 90F in the rooms there at night, with the window open. Then I moved into a campus apartment....and my roommate was one of those outdoors-types who hated having the window closed. So the AC didn't get much use. Go figure. Fortunately, that was second semester, and it was only warmer toward the end, so I didn't have to deal with it for long. I had all the cold I could stand anyway - he also liked to have the windows open in the winter.
 
Go to your local equipment rental and rent a diesel air compressor. Park it out side and run the hose in through the window. Use it to cool the room with vortex tubes. It's going to be a little noisy but vortex tubes can output temps around -70F. vortex tube
 
Originally posted by: FrankSchwab
Boy, HT sure has hit rock bottom...

Five seconds with Google and "Portable air conditioner" gets you:
http://www.compactappliance.com/xq/JSP....romotion=Google%3EPortable%20Air%3EAd1

White boxes that sits inside the room, with a dryer hose that goes out a window. With suitable camouflaging, the dryer hose could probably look like a fan from the outside. Costs $500, and has an EER rating of 12.0, and cools up to 400 sq. ft.

Keep cool,

/frank
Click to expand...

Yes it has hit rock bottom with responses like this. It cant be an AC unit. CANT. Anything w/ a compressor, Freon, or factory looking device won?t work. I need something that looks home built, doesn?t sound like an AC unit, and can be easily called a "computer cooler". The people Im working for are ignorant, not dumb.
 
Originally posted by: FrankSchwab
Boy, HT sure has hit rock bottom...

Five seconds with Google and "Portable air conditioner" gets you:
http://www.compactappliance.com/xq/JSP....romotion=Google%3EPortable%20Air%3EAd1

White boxes that sits inside the room, with a dryer hose that goes out a window. With suitable camouflaging, the dryer hose could probably look like a fan from the outside. Costs $500, and has an EER rating of 12.0, and cools up to 400 sq. ft.

Keep cool,

/frank
Click to expand...

He's concerned about power consumption. Those portable air conditioners are 10,000BTU's or more. A small air conditioner, like around 5,200 BTU's is probably the best option.


Given the OP's restrictions, any solution is going to be cumbersome, expensive, and possibly dangerous (think "fire hazard").

That said:
Get two radiators, like from an old air conditioner. I don't know what's inside them, if it's safe to just release into the air or what....but the eventual idea:
water blocks. CPU-style waterblocks. One for the hot side, one for the cold side, each to its own radiator and pump.
The hot side radiator could be contained, and air blown over it. This would be ducted into a hose and fed outside, or indeed, the entire assembly could remain outside. It still would benefit from shading and a source of convection.
The cold side radiator would similarly have a fan blowing over it. This would serve to provide cool air, and it would condense moisture out of the air like a normal air conditioner.

Using this system, it might be feasible to daisy-chain two or possibly three peltiers together, depending on how hot and cold the respective sides get.

Temperature monitors are definitely something you'd want to have, and if this contraption is to be left alone for any amount of time at all, it should have some kind of thermal cutoff circuit, perhaps something with a thermistor and a relay. And something to monitor the pumps. Should the hot side pump fail, the water inside could perhaps boil, which could burst a pipe. The next result would be fried peltiers. Should the cold side pump fail, the result may not be as disastrous, but you'd probably wind up with bursting pipes/hoses from frozen water. The peltiers should survive it though.

Also consider antifreeze in the cold side. For additional cooling capability, I've heard that WaterWetter is a good additive to use. It's supposed to improve the thermal transfer capacity of water, or something to that effect.
 
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