Tuesday, June 20, 2006

Homemade air conditioner!

Back when Bo and I started rooming together at U of I we had no air conditioner. So what do you think 2 engineering types do when it's the first week of class and you're sweating to death in a cramped dorm room? You build your own air conditioner! That's why I like this little contraption.

Apparently the cooler is full of ice water. The copper coil is submurged in the water and an aquarium pump is used to pump water through a circuit from the coil in the cooler to the coil strapped onto the fan.

Bo and I had a similar system, but since I came up with part of the design I naturally think it's a little better than this one. Rather than using a 2 heat exchanger system (one in the cooler and one on the fan) we simply pumped ice water from the cooler to a heat exchanger. Even better, I managed to get an old radiator to use as a heat exchanger. This had the advantage of having much more surface area than a simple copper coil. It was large enough to cover two small fans rather than one.

I suspect that the device in the picture would only create a cool breeze, while the radiator system actually cooled the room fairly well. Of course it did come at a cost. Bo and I had to fill the cooler with ice every 30 minutes or so. At least the ice in the dorm was free.

In the end, it turns out that the best part of the air conditioner system was the attention. Our room was a small time tourist attraction for a while, and even a couple semesters later I had a guy ask me "Did you know there were two dudes in Allen Hall who built their own air conditioner?"


At 2:49 PM, Blogger jl said...

i remember that air conditioner! go you.

At 12:06 AM, Anonymous Bo said...

Dude - I really have to comment on this one :) Living with another engineer (and tinkerer) in the dorms, with all these problems looking for solutions staring us in the face, those were great times. I'm amazed that we became famous enough to be part of the folk lore of exhalted Allen Hall. And yeah, I think our system rocked. The truck radiator is *designed* to do heat exchange from liquid to air - complete with fins, I'm sure we got someting like 100 times more heat exchange per delta time than the dude with the random coil strapped to a fan. Plus, we had two massive-but-slow box fans (that we put one in front, one behind the radiator if I remember correctly) and a smaller high-speed vortex fan, so we had more air movement as well.

Gotta hand it to us. Okay, really you, since you brought all the materials and built the thing. But still... -Bo

At 8:01 PM, Blogger Mr. Engineering Johnson said...


That was a fun time! I was just thinking the other day that we should have tried adding salt to ice-water so we could get the T0 of the exchanger a little bit lower.

As I recall the only real problem (aside from needing ice every 30 minutes) was that reducing the temperature in the room gave us a relative humidity of near 100% Still, it was more comfortable than the other rooms in the dorm.


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