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The Dorm Cooler

It's getting hot in Delaware. Every day the temperature gets a little higher, and by mid-May, the humidity will creep up to summer levels. What is a cash-strapped student living in a dorm without A/C to do?

In my building, we are not allowed to use A/C units due to the amount of power they consume. Running computers, lamps, and even your own body heat add to the ambient temperature to make the average room even hotter than it is outside. It costs nothing to close your blinds and keep a fan blowing at the ceiling to circulate the cooler air at floor level, but for me, that wasn't enough.

My solution was built using about $40 worth of parts from Wal-Mart.

The original idea for this project came from a post I saw last year on lifehacker.

The basic idea: If you can put something really cold in the path of a stream of moving air in a sealed room, you'll be able to cool it. Cold air has less ability to hold moisture, so significant cooling will also dehumidify the room and make it more comfortable.

The implementation: Bend a piece of copper tubing, like what you would use for an ice maker or refrigerator ($15), into the shape of a spiral. Use zipties ($2 for 30) to attach it to a round fan (variable price), maximizing the exposed surface area of the copper.
Attach a 5 ft length of flexible tubing ($2 for 10ft) to each end of the copper spiral using hose clamps ($0.80 for 2).
Place a submersible pump ($21) inside of an insulated styrofoam cooler ($3). Attach one of the flexible tubes to the output of the pump, and route the other tube into the cooler (it will act as a return line). Make sure that the power plug for the pump is outside of the cooler.

Fill the cooler with ice water. Cut a notch into the lid of the cooler so that the water lines and power wire can be neatly run into the cooler while it is closed.

Use zip ties to tidy up the water lines, if necessary. Plug in the pump to make sure that everything is flowing correctly, and check for leaks. If your pump is adjustable, set it for maximum flow.






After about 30 seconds, touch the copper coils and check if they are cold. If so, turn on your fan and wait for the magic of dorm room cooling.

If your cooling system is truly effective, it will cause water to condense out of the air. It should be visible within five minutes of operation on a day with low humidity. I haven't tested my system yet on a really humid day. Condensation will appear as drops of water, like this:



Just like a conventional air cooling unit, this device will work best when air does not leave or enter the room. In other words, close all open windows, and avoid leaving your door open. Also... I used ice for the test run of this device, but anything cold could be used in the reservoir. Ice packs, cold drinks, snow...whatever.
Remember that you're only capable of transferring the heat from your room into the water inside the cooler; in other words, all the cold from the cooler will be transferred to the air of your room, but no more than that. So the colder the material in the styrofoam, the more efficient the heat exchange on the surface of the coils will be.

In theory, any thermally conductive material will work for the heat exchange element. If you're resourceful, the best thing to use would be an A/C core or heating radiator from a car, because they are engineered to facilitate heat exchange between air and their coolant.

Good luck.

The exhaust system

First post on a blog. This is just a cool place to host my junk and ideas whenever.

Today I gained a measure of aromatic privacy by constructing an exhaust system for the window of my dorm room using....
Two of the cheapest LASKO box fans I could find (3 speed, about 18.5"x18.5")
Roll of duct tape
Some scrap cardboard



Just shoving the fans in the window would have been enough to maintain a flow of air from the hallway into my dorm, but I noticed that it was wasteful and there was some backpressure coming back into the room through, over, and between the fans. I measured out a piece of cardboard to fill the space between the glass of the window and the fans and sealed it with duct tape to the top of the fans.

Air moved by a fan moves along a path through the disc traced out by the motion of its blades, so any backpressure is normally free to push back through the plastic grates of the fans around that disc without any competition. This can cause turbulence and hinder the direction of the air flow in the room. To compensate for this, I used duct tape to seal a 1.5" border from the outside edge of each grate, roughly closing off most of the area outside the blades that was vulnerable to backflow.

It's not a perfect system, but it's a vast improvement if you want to keep the smells from your room out of the rest of your dorm building. This might work for people who are cooking bacon, don't use deodorant, or are looking to hide the scent of....ah...incense.

Here's a quick video just to illustrate how this will the air coming IN through your door, not out...