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Hardware Hacking Technology

Homebrew Air Conditioning for Under $25 832

Posted by timothy from the ice-is-free-after-all dept.
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."
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Homebrew Air Conditioning for Under $25 More

Homebrew Air Conditioning for Under $25

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  • Its going to be hot soon (Score:5, Funny)

    by Anonymous Coward on Monday June 13, 2005 @05:45PM (#12807319)
    I hope his server isn't in his room, because all the thermodynamics courses in the world wont teach you about slashdotting.

  • And you can place it... (Score:4, Funny)

    by peter_gzowski ( 465076 ) on Monday June 13, 2005 @05:45PM (#12807324) Homepage
    ...right next to your webserver.
  • Move to San Francisco.

    Today it hit 70F, and the news stations are talking about "the heatwave of 2005".

  • Minor nit (Score:5, Insightful)

    by Roadkills-R-Us ( 122219 ) on Monday June 13, 2005 @05:46PM (#12807336) Homepage
    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.

    • Re:Minor nit (Score:3, Insightful)

      by kiatoa ( 66945 )
      Exactly, I think the financial folks talk about trading off initial costs for long term running costs. Someone is footing the bill on the electricity for making that ice. BTW the overall energy efficiency of this setup is substantially lower than the equivalent decent window air conditioner (COP of the air conditioner is much higher than the COP of an ice maker due to smaller delta T iirc).

    • Re:Minor nit (Score:2, Interesting)

      by bhtooefr ( 649901 )
      Hmm... Gallon jugs of water in the freezer?

      Still uses energy, mind you, but that takes care of the ice water.

      Also, I thought that routing the water OUT was a bad idea. Why not catch the water in another bin, or in jugs, and freeze that? Makes SO much more sense...

      • Re:Minor nit (Score:3, Insightful)

        by gl4ss ( 559668 )
        look.. using a freezer(that you run in the same area as you're trying to cool) to cool a room isn't that smart.

        I thought the guy had built up some swamp cooler or something like that, as that does really work - but this is just friggin lame/stupid in the long run to use. now... he could refine the idea quite a bit - use ground cooling to keep the water cool for example(just bury some copper pipes or some container a meter into the ground).

        "hey i built a cooler. well, i just brought some ice water to my r

      • One minor issue (Score:3, Insightful)

        by ad0gg ( 594412 )
        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.
    • Seriously, especially since for about $120 you can get a low end window unit [thebuzzelectronics.com].

    • Re:Minor nit (Score:5, Insightful)

      by LurkerXXX ( 667952 ) on Monday June 13, 2005 @05:59PM (#12807485)
      Why you can get the ice out of the freezer/refrigerator in your kitchen. It just costs a little electricity to make. It makes it by using a condensing coil to use a gas medium to pump heat from the freezer are to coils on the back of the fridge which... then heats the room you are trying to cool. DOH!

      • Re:Minor nit (Score:5, Funny)

        by tomhudson ( 43916 ) <barbara DOT huds ... a-hudson DOT com> on Monday June 13, 2005 @06:13PM (#12807598) Journal
        It's not a minor nit-pick. Its a major flaw. His setup is so much more inefficient than even a cheap ($100) AC.

        If he wants to be cheap, why not just take an old fridge ($20), remove the doors, and use the fridge to block the door to his room? Leave the coils facing out into the hallway, and his room becomes cooler - plus the light will always be on, so he can see wtf he's doing.

    • Re:Minor nit (Score:3, Funny)

      by v1 ( 525388 )
      If he's into thermodynamics he should realize the reason this is appearing to be a cheap way to AC is he's ignoring the need for the supply of cold water. (ice) Wouldn't he cut out the middleman here (and thus, theoretically increase efficiency of the system) by simply leaving his freezer door open with a fan in front of it?

      I suppose it might still work running on cold tap-water, but then that could make for an expensive water bill. Although not nearly as much as running your freezer with its compressor

      • Re:Minor nit (Score:3, Insightful)

        by Cutie Pi ( 588366 )
        Actually there's another interesting thing about thermodynamics...

        Many people think that if you leave the refrigerator open, it will cool down the house. However, all a refrigerator does is take heat from its inside and move it to the outside. That's why those coils in the back are warm. Thus, if you open up the fridge to cool the house down, all you'll do is make the place warmer (since the efficiency isn't 100%). Also, you'll probably burn out the motor in your refrigerator.

        I'll grant that in your parti

        • Re:Minor nit (Score:3, Informative)

          by emarkp ( 67813 )
          Um, that's the point. His setup is thermodynamically equivalent to opening up the fridge. Thus, he's not actually reducing the heat in the room, he's just moving it around.

    • Re:Minor nit (Score:5, Informative)

      by racermd ( 314140 ) on Monday June 13, 2005 @07:25PM (#12808302)
      I hit this through the mirrordot link from above...

      This is exactly how a good thermal heat-pump operates. However, a few "upgrades" would make this perfectly viable for a home of 1500+ sq. feet.

      1: Make it a closed-loop system, or even a dual-loop system.
      2: Use a good radiator and heat-block. Think of a water-cooling rig on a PC, but in reverse and a much larger scale.
      3: Use the earth, itself, as both the source and destination of heat.

      Most people that have done this for their homes use the earth as a natural heat sink. If it's new construction, they typically dig shallow, but wide. In a retro-fit, they'll drill deep and narrow. Either way, the earth holds a pretty steady temperature below 6-8 feet or so. All that's needed is a way to put heat into it when you want to cool off and a way to get heat out of it when you want to warm up.

      This way, all that you spend money on is the electricity to pump the heat-carrying fluid/gas/whatever into and out of the tubes in the ground. If that isn't enough, a small furnace and/or A/C unit can supplement, if need be. Either way, the energy consumed from the utility companies is a fraction of "normal".

      I have plans to build a new home in the next 3-5 years, and I'm looking at all sorts of alternatives to just about everything that consumes energy in a home.

      1: Geothermal heat pump(s) for climate-control.
      2: On-Demand, CNG water heater (i.e.: no tank to keep warm)
      3: Solar-powered radiant heat (suplements forced-air from #1)
      4: On-Demand lighting (sensors that detect room occupancy)

      I'm missing a number of other things I could do, but the goal is to have a home with all sorts of modern conveniences while trying to reduce the energy usage associated with most of them. It's tempting to add a water-cooling loop to the climate-control system for the comptuers. They're already producing heat, so why not just send it directly to it's destination and avoid that pesky conversion to heated air?

      Getting back on-topic, this guy hasn't done anything new. In fact, it's rather wasteful to just use a coil of copper tubing tied to the back of a fan. The fact that he's using ice water (as mentioned in other posts) does nothing to save energy costs. After all, he's got to power a freezer to make the ice to begin with, which offsets most of the savings. Never mind that the heat from the water (plus the heat from the machine, itself) went into the living space that he's trying to cool.

      And that he's a student, and *probably* not paying for much, if any, of his utility costs. But I digress...

      • Re:Minor nit (Score:3, Informative)

        by evilviper ( 135110 )

        2: On-Demand, CNG water heater (i.e.: no tank to keep warm)

        Unless they've improved drastically in the past few years, these systems are terrible, and they only sell because they trick the "green" crowd into believing they're wonderful, and because of cheapo construction companies who buy this cheap junk instead of a more expensive tank-based water heater.

        Basically, when you turn on the hot water, you can expect the first gallon to be scalding hot, and the rest will be barely warmed above room tempuratur

  • DOA (Score:2, Informative)

    by AmigaAvenger ( 210519 )
    I'm a student, with limited funds and a cheap house without air conditioning. To avoid dying this summer, I've built a primitive air conditioner. It's a basic heat pump, using water as the medium. You'll probably need to fiddle a bit with the dimensions of the supplies based on your resources and preferences.

    Materials:

    Salvage from around the house a:

    * large fan
    * garbage can

    Grab from Home Depot:

    * 25 feet of 1/8 inch outer diameter (OD) copper tubing (~ $14)
    * 20 feet of 1/8 inch inner

  • Thinkcycle (Score:3, Informative)

    by bigattichouse ( 527527 ) on Monday June 13, 2005 @05:47PM (#12807345) Homepage
    You may want to post this on thinkcycle.org as additional information for some of their cooling projects

  • Siphoning (Score:3, Funny)

    by sxltrex ( 198448 ) on Monday June 13, 2005 @05:47PM (#12807349)
    It certainly does suck!


    sorry...

  • Too bad it's not child compatible.
    (Unless my downstairs neighbors were hoping for rain in their kitchen.

  • MirrorDot (Score:4, Informative)

    by eric434 ( 161022 ) on Monday June 13, 2005 @05:47PM (#12807354) Homepage
    Next up, a $24 watercooling rig for his web server.

    http://www.mirrordot.org/stories/5cb66a4a72a5269bc 29e9dd8f982b3da/index.html [mirrordot.org]

  • Congrats on making your PH.d. pay for itself! (Score:5, Insightful)

    by jeffmeden ( 135043 ) on Monday June 13, 2005 @05:48PM (#12807360) Homepage Journal
    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.
    • Well, you could put the heated water on the boiler - there! You save your self the heating, too! :)
    • Depends. Around me (and it's nearly 90 outside today) the groundwater temperature is about 59 degrees (both in F, of course). Even the taps come out low 60s year round, once the slug of heated water in the house is gone.

      Not green, as the water is just getting wasted, but it may be cheaper for the water than the electricity + air conditioning. Especially if you're not paying for the water bill ;-)
    • 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)

      It's currently 7:51pm in New York City, and the temperature outside is about 85F. The high today was 94 in Brooklyn (my hood).

      The tap water temp, though, is still a blissful 61F (after letting it run for about 15 seconds). That's practically icewater, compared to the outside temp.

      Since very few residential customers in the city get bille

  • Canada (Score:5, Funny)

    by Geekboy(Wizard) ( 87906 ) <spambox@theap t . o rg> on Monday June 13, 2005 @05:48PM (#12807366) Homepage Journal
    Dude, you're in Canada. Open the window.

    Now you just have to figure out how to keep the snow off of the carpet.

    • Re:Canada (Score:5, Informative)

      by RobinH ( 124750 ) on Monday June 13, 2005 @05:56PM (#12807448) Homepage
      Dude, I'm in Canada... was 92 fahrenheit here on the weekend. Plus humidex.

      • Re:Canada (Score:4, Informative)

        by Anonymous Luddite ( 808273 ) on Monday June 13, 2005 @06:16PM (#12807626)
        >> 92 fahrenheit here on the weekend.

        weekend? Ontario's been a rotten b*stard for the last week - 30 Celsius + humidity every day.

        I'm sitting between two fans, beer in hand, AC cranked. My effing hydro bill is going to make me cry...

        • Re:Canada (Score:3, Funny)

          by pipingguy ( 566974 )

          We were driving through Brossard Sunday looking for Pont Victoria (most people in the Montreal area end up looking for this stealth bridge at one time or another) and passed one of those digital readout advertising signs that was flashing time and temp. It said -11 degrees C.

      • Re:Canada (Score:3, Insightful)

        by flithm ( 756019 )
        I'm quite upset with you. No self respecting Canadian, or any member of any country other than the lagging-behind-the-times-USA uses non-metric measurements. Canada and fahrenheit should never be mentioned in the same sentence, unless it's one of the following:

        "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."

    • Re:Canada (Score:4, Informative)

      by Quasar1999 ( 520073 ) on Monday June 13, 2005 @05:59PM (#12807487) Journal
      It's currently 28 degrees outside... check for yourself (http://weather.uwaterloo.ca/ [uwaterloo.ca]), if you can make snow at that temperature, I'd be impressed.

    • Re:Canada (Score:3, Funny)

      by KillerBob ( 217953 )
      I'd do that, but it'd make running the air conditionner even more expensive.... It hit 35'C with 70% humidity today, making it feel like 42'C (107'F).

      Can't wait until August, when it really gets hot. :)

  • Environmentally friendly? (Score:5, Insightful)

    by whoever57 ( 658626 ) on Monday June 13, 2005 @05:48PM (#12807369) Journal
    It's cheap, environmentally friendly (just fire the waste water off to your garden)
    So, if it is environmentally friendly, just where did the "ice water" come from?

    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?

    • Re:Environmentally friendly? (Score:4, Funny)

      by LurkerXXX ( 667952 ) on Monday June 13, 2005 @06:14PM (#12807608)
      So, if it is environmentally friendly, just where did the "ice water" come from?

      Ice Pixies magic it up, so he doesn't have to run a refridgerator/freezer to make the ice. Because, you know, those actually produce heat inside the house, which he is trying to get rid of... Pixies. Yeah, that's it.

  • Beer (Score:5, Funny)

    by supe ( 163410 ) * on Monday June 13, 2005 @05:49PM (#12807380) Journal
    I think that his garbage can full of ice water should at least have a few cold beers. I mean really, he's in college!

  • Congratulations (Score:5, Informative)

    by overshoot ( 39700 ) on Monday June 13, 2005 @05:50PM (#12807388)
    At first I thought you'd reinvented the swamp cooler [arizona.edu]. On RTFL, however, I find that you've actually reinvented the 18th-century icehouse cooler, which is notably less efficient (like, where does the heat from the icemaker go?)

    It didn't seem all that likely that most /.ers would care about evaporative cooling, since even in Arizona they only work part of the year (like now, although today the Phoenix dew point got up to 10C. I woke up just knowing it had gone up because the cooler was blowing full speed and it still wasn't all that cool.) Never mind next month when the monsoons start. AC time then for sure.

    • Swamp Coolers... (Score:4, Interesting)

      by GI Jones ( 21552 ) on Monday June 13, 2005 @06:56PM (#12808020) Homepage
      I had never heard of a swamp (evaporative) cooler until I moved to AZ. At first, I didn't like the idea of adding a ton of humidity to the air in order to cool some space, but when I bought my first house, I learned that I LOVE swamp coolers.

      Newer homes never have them, but the older house that I bought (built in 1979) had a monster one installed on it. During the early parts of summer (when the humidity is low) I can keep my house at 72 degrees when the outside temp is about 100 and my electricity bill is $65/mo.

      If I ran my AC unit and kept the house equally as cool with it, I would be looking at no less then a $150 in early summer and $200+ as the temp gets into the range of 110+.

      At this point, what I would love is a thermostat that runs both my swamp cooler and AC unit and can determine when to use one versus the other and switch automatically between them. Anybody know of such a device?

      cheers.

      • Re:Swamp Coolers... (Score:4, Informative)

        by Tsu Dho Nimh ( 663417 ) <[abacaxi] [at] [hotmail.com]> on Monday June 13, 2005 @10:24PM (#12809608)

        what I would love is a thermostat that runs both my swamp cooler and AC unit and can determine when to use one versus the other and switch automatically between them. Anybody know of such a device? Nope, and you won't find one. It's a fast way to kill your AC.

        I had a tenant who manually switched between AC and evap every day, when we were in one of those "not quite dry enough for evap" months. Her theory was that in the PM, when the RH was low, she could use the evap, then use the AC the rest of the time. Then she called me because the AC was not working.

        The first day or so of an AC switchover from evap is when the AC has to remove all that moisture left by the evap. The tenant had been switching often enough that the humidity removed made a sheet of ice on the coils and the AC died. Because it wasn't cooling rapidly enough, she cranked the T-stat down as low as possible, which made the icing worse. Fortunately, there was no permanent damage ot the AC, but she had to swelter with no cooling until the ice caking the coils melted. She wasn't willing to pay the AC guy his hourly to stand there with a blow dryer and melt yhe ice.

  • evaporative cooling is great, as long as you aren't jacking up your indoor humidity levels which can cause all kinds of nastiness like mold that can kill you or get your building condemned.

    If you do this in a non-arid climate, you're asking for trouble, IMHO.
  • I'm not sure whether this would be more energy efficient or not, but I would bet not. I mean, really it's using electricity like an air conditioner would -- it takes electricity to make the ice in your freezer (or make the ice you buy from the store).

    However, he did say it worked alright with cold water as well and water is included with rent in my apartment whereas electricity isn't. I think I might have to try this.

  • thermodynamics? (Score:5, Funny)

    by csimicah ( 592121 ) on Monday June 13, 2005 @05:53PM (#12807425)
    Wait... this retard thinks that using his fridge, inside his house, to produce ice... then cooling with the ice... is going to make his house cooler? He could accomplish the exact same thing by just opening his freezer door, right? I hope this kid's Thermo professor sees this and kicks him out of school.

    • hmmmm.... (Score:5, Insightful)

      by MarcoAtWork ( 28889 ) on Monday June 13, 2005 @05:59PM (#12807476)
      #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.

      • costs (Score:4, Insightful)

        by SuperBanana ( 662181 ) on Monday June 13, 2005 @06:54PM (#12808000)
        #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.

        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.

    • Re:thermodynamics? (Score:3, Insightful)

      by PondScum ( 51944 )
      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.

  • I don't think this would be very helpful in Florida, but you never know. I wonder if the inventor has tried it in 100% humidity/100F+ weather? :-) The major sticking point is needing the ice water to begin with of course.

    Being without A/C for a week after the hurricanes last year was no fun at all! I'm just glad our generator had enough juice to power a window air conditioner (but the gasoline cost a fortune :().

    Building a home brew A/C that was energy effecient would be a very useful project this year,
  • Not a terrible bit of redneck engineering (and I mean that is a positive way), but I can't imagine anyone having a limitless supply of ice and water.

    Not that the idea I'm about to present is any better, but this guy really needs to make this a closed system. Put that bucket'o'water in the refridgerator (or freezer), get an aquarium pump, and run the pickup line to the bottom of the bucket and the return line on the top of the bucket. Cut out the door gaskets to allow the lines to go through, and just add s

  • Most enviro friendly method to not overheat (Score:3, Interesting)

    by WillAffleckUW ( 858324 ) on Monday June 13, 2005 @05:59PM (#12807486) Homepage Journal
    is just to replace the standard incandescent lightbulbs in your house with compact flourescent bulbs.

    this will result in you using about 1/8 the electricity to get the same light, but drop the heat output from lighting - a major contributor to household heat - to virtually nil.

    I used to have a problem in my new house with having to get a fan until I realized it was mostly heat from lights that was making it hotter than a normal open window breeze could cool. Then I replaced my incandescent bulbs (well, most of them) with flourescent bulbs and suddenly it was cool enough I didn't even need a fan at all.

    Now, if the external temperature is above about 98 degrees Fahrenheit (30 C, I think), you may still need to do the water evaporator you describe, but the energy used by it will still be lowered by switching to compact flourescent bulbs for lighting.

    Oh, and get a flat panel LCD monitor - that will save a lot of energy usage and heat output as well.

    Save the fan to cool off your computer, not your room.

  • addressing all the flames/legitimate concerns... (Score:5, Informative)

    by inkey string ( 35594 ) on Monday June 13, 2005 @06:22PM (#12807678) Homepage
    number one, yes i realise that in a closed system freezing ice to cool yourself off is foolish. this is why i make ice in the kitchen, and cool my room off at night.

    which addresses the why no recirculation/you need an infinite supply of ice criticisms. this was designed to cool me off before bed, so i could fall asleep without wanting to kill myself. once the bucket runs out of water/ice, it just becomes a regular fan which is fine once the house cools off in the wee hours. plus i dont have to worry about knocking anything over in a morning daze.

    ive rigged it up to a slowly flowing garden hose which will keep things cool indefinitely, but i find it easier and a bit cooler to just pick up a big bag of ice and dump it in when it gets really hot.

    anyways, take it or leave it. and to the graduating chemmie that said he was ashamed to call me a student - come visit me at my office by the weef lab (e2-1311), im sure i can address any of your concerns to my satisfaction.

  • CostCo $50 for 5000 BTU (Score:5, Informative)

    by jbridges ( 70118 ) on Monday June 13, 2005 @06:58PM (#12808047)
    Spend another $26, and buy a real airconditioner for $50 at CostCo.

    It's $99.99 with an instant $50 off rebate at the register.

    Less work too.....
    • Spend another $26, and buy a real airconditioner for $50 at CostCo. It's $99.99 with an instant $50 off rebate at the register. Less work too.....

      Yeah, and if Linus Torvalds had dropped some cash for UNIX, he wouldn't have had to write his own. Less work there, too.

      I have to ask if you've ever built anything yourself, because there's a real pride to be enjoyed in knowing that what's working for you was built by you that seems to have passed you by - I'm writing this message on a computer I built mys

  • Bend the copper using sand (Score:5, Informative)

    by ishmalius ( 153450 ) on Monday June 13, 2005 @07:03PM (#12808093)
    I don't know if this guy ever took shop class, but the simple old trick of filling the part of the copper tubing to be bent with sand will help prevent it from collapsing from a too-tight bend.

  • While the freezer probably isn't the best way... (Score:5, Interesting)

    by foxtrot ( 14140 ) on Monday June 13, 2005 @07:08PM (#12808142)
    ...to cool a room, as has been noted repeatedly, a few refinements that can be done easily and cheaply:

    1) Get a second trash can. Drain to trash can number 2. This will allow you to save water, plus:

    2) Put salt in the water. The ice and chilled water mixture gets colder with salt.

    You probably don't want to drain salt water to the yard. :)

    You can run from one trash can to the other, then when it's done draining, swap one can for the other and ice down the other can. If you've got some freezer space to dedicate to the project, the bottles of ice are probably an excellent idea-- have a set in the freezer and one in the heat pump.

  • Homebrew swampcooler (Score:3, Interesting)

    by gessel ( 310103 ) on Monday June 13, 2005 @08:14PM (#12808697) Homepage
    Years ago, during a heatwave in Oakland, I built a homebrew swamp cooler with some muffin fans and a mist nozzle from McMaster (like 32215K11).

    From thermodynamics, the say you have 1kg of water to work with:

    Changing it from ice to water: 334kJ
    Raising it from 0C to 25C: 104kJ
    Converting from liquid to vapor: 2,260kJ

    Compared with vaporizing water, melting ice is trivial.

    For swamp coolers to work, the humidity has to be low--if it's high the ice bucket trick is a good one. But for those in dry hot climates, a swamp cooler works well.

    I connected mine to a hose spigot with 1/8" tubing, which supplied a continuous flow of water to the mist nozzle, which was mixed with a good flow of hot dry air from the fans, and resulted in a good flow of cool slightly damp air.

  • Capacity (Score:3, Informative)

    by ColaMan ( 37550 ) on Monday June 13, 2005 @08:39PM (#12808880) Journal
    This is all very well and good, but he's missing one thing - capacity.

    Air-conditioning systems are sometimes rated in "tons". That's "how many tons of ice required to melt in a 24hr period to get the same cooling effect."

    Surprisingly, in AC terms, a ton is not a very large unit. A typical car air-conditioner is about 2-2.5 tons. This size AC is capable of cooling about half a house. So, a 5kg bag of ice? Forget it. Go buy a real air-conditioner. Scrounge around - 30 bucks can buy a decent old second-hand unit.

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