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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."
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.
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.