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Homebrew Air Conditioning for Under $25
inkey string writes "Summer has arrived, and I've been busy slowly overheating in my student house without central air.
I decided to put my thermodynamics classes to work however, and produced this ~24$ homebrew air conditioner. It'll cool a room to a comfortable level in 15-20 mins, and will run for a few hours on a garbage pail full of water.
It's cheap, environmentally friendly (just fire the waste water off to your garden), and makes a good one hour project for a quiet evening."
From the article: "cheap, environmentally friendly".
From who.int: "Billions without clean water": link
The guy has no clue how lucky he is in his "student ghettos don't have gardens" home to have clean water to throw around.
Just great, assuming you have an infinite supply of free ice water. Add teh cost of the ice machine, and it costs a bit more than $24.
>> I hope his server isn't in his room
It's actually a University of Waterloo server. I'm sure the sysadmin is gonna love this sudden DDOS.
http://request-header.info
But sadly this isnt that revolutionary, nor is it very 'green'. It takes a cold source of water to work, and if you have none in your area (tap water wont cut it unless you happen to get fed from a pipe running through a glacier) you have to get cold media from your local refridgerator/freezer. Why not instead rig a direct cycle through your cooling appliance of choice to offer a small, localized cooling effect? It also wouldn't waste water. Just remember, don't try to cool the room with the freezer in it.
Unless you have a solar or wind-powered refrigerator, I suspect that the overall system is not actually all that environmentally friendly. What is the energy efficiency of the system?
The real "Libtards" are the Libertarians!
#1 you can buy a bag of ice at the gas station/convenience store, not free but then neither is the electricity to run your freezer.
#2 even if you used the house freezer, you shut the door and basically you're pumping heat away from the bedroom into the kitchen, obviously you won't get huge temperature differentials, but 5-6C feels very noticeable when you're trying to fall asleep and it's too hot to do so.
-- the cake is a lie
The goal was cooling a room.
While I agree that there are far more elegant ways to do this, You can still cool a room this way and not disobey the laws of Thermodynamics.
The heat generated by the Fridge stays in the Kitchen. Close the door and now you have effectively transfered heat from the cool room (bedroom or livingroom) to the kitchen. It is now far easier to relax.
Think it through before calling someone a moron.
Isn't this just a swamp cooler? Aren't they rendered useless in humid environments? Wouldn't reading this article be a complete waste of time for the majority of us?
If he's getting ice from the freezer in his apartment/room, it is negating his attempt to cool his apartment/room. Heat removed from water in the freezer to make the water freeze is put right back into the house by the thermal coils on the back of freezer/refridgerator.
Have you ever been to a turkish prison?
The store needs to make a profit on top of the cost of the electricity to maintain the machine, and the ice...
...supplied by the ice company which bought the machine, maintains it, and freezes the ice, and trucks it to the store from their "plant"...and make a profit.
You do realize that 1kW/hr costs about 22 cents, whereas a 20lb bag of ice costs about $5, right?
You have to move 330J of energy to freeze one gram of water, basically. We'll assume a 50% efficiency here (pretty poor, I believe). A bag of ice, say, 20lb- would need about 3 million joules (watt-seconds), or 6 million watt-seconds of electricity. That's 1662 Watt-hours, roughly.
Or about 36 cents.
#2 even if you used the house freezer, you shut the door and basically you're pumping heat away from the bedroom into the kitchen, obviously you won't get huge temperature differentials
Most refrigerators are virtually incapable of pumping that much heat (there's a reason they're insulated), and furthermore, are designed to work at a temperature range 60-90 degrees cooler than what you're asking of it. Ever noticed that a fridge takes forever to get from room temperature down to operating temperature?
This idea is so stupid, I can't believe I just wasted 5 minutes on this post. I want that 5 minutes of my life back.
Please help metamoderate.
Actually, the prices Californians pay for power offsets the cost to deliver electricity to customers in the Northwest. I'm reminded of the slogan at Chilkoot Charlie's in Anchorage: "We cheat the other guys and pass the savings along to you."
And, yes, I work for a power company and know how the system works.
The Spoon
Updated 6/28/2011
"That Fahrenheight 911 show was pretty good eh?"
"Fahrenheight? It's too damn hot in here for your jibberish. Go fill up the $24 AC with ice so we can get the temperature to a respectable level of Centrigadey goodness."
If you live somewhere that it gets significantly colder at night than in the daytime, that works.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
As others have said, this setup has all sorts of problems, from a reliance upon a source of ice that may very well be dumping more heat into the local environment than it saves, to wasting water.
Very good point. Just where is the fridge located that produces the ice? Where is it putting the heat. The fridge is not included in the price of the project. Why not just take the door off the fridge and mount the fridge in the wall to expell the heat elswhere?
For those who don't know, fridges use a small compressor because they are cooling a small insulated enclosed space. They do not provide enough cooling to deal with the heat influx of a large room. It's BTU capacity is way undersized.
His fridge would not produce enough ice to keep his cooler supplied. The ice is a overnight creation cold storage medium to provide a short coling burst. This is not a cooling solution.
Air conditioning compressors displacement is designed to be effecient at expected cold side pressures and high (hot) side pressures. A fridge compressor is sized to work with lower suction pressures (larger displacement) for the creation of Ice in the freezer compartment. Running it with constantly elevated tempratures will overload the compressor causing ineffeciency.
When buying a compressor, they are sized for high temp use (air conditioning) and low temprature (freezers) The diffrence is the displacement is sized to the expected low side pressure.
High pressure moves more BTU/watt. Low pressure is for a large temprature differential.
The truth shall set you free!
With all respect to university resource limitations, you would think they would be most proud of having their students attracting world attention, especially for something laudable.
Web pages for professors hardly get any news coverage, and these people are supposed to be at the top of the game. Surely research funding would leap to another quantum level if professors discussed on their websites how much impact or influence their research has, especially if those sites attracted page hits from large numbers of the public.
The adage of publish or perish seems to become perish and perish (i.e., lose, lose) when it comes to a little slashdotting.
Know your pads. One time pad: good for cryptography. Two timing pad: where to take your mistress.
I dont see any reason why this wouldn't work
here in australia i have a few mates that have set up sprinklers on top of the shed, can easily drop the temp inside by a few degrees which makes all the difference on a 40deg day
Where he of course met Guinan and Data and was almost killed by time shifting aliens that were attempting to steal our souls. Wouldn't that be anyones worst season?
"Genius may shine aloof and alone, like a star, but goodness is social, and it takes two men and God to make a Brother."