| Here's a cheap and simple way to build an | | | | container will quickly become cool, since metal is an |
| air-conditioning unit using simple household items. To | | | | excellent conductor of heat. |
| build the unit, the items and materials you will need | | | | Lastly, place the fan in front of the opening, and put |
| are: | | | | a sheet or whatever you have (which serves as a |
| · Fan | | | | lid) on top of the duct, leaving a small opening for the |
| · Wood (pieces of 2x4) | | | | air to blow out of, after making its way around the |
| · Metal container (such as a garbage can, | | | | duct. You may also want to seal part of the opening |
| approximately 15 inch tall by 13 inch diameter) | | | | above the fan with an old newspaper so that there's |
| · Circular saw | | | | no unnecessary gap above the fan where air can |
| · Nails and a hammer | | | | escape before being cooled. This is a crude design |
| · Aluminum metal repair roll, thin sheet (18 | | | | for sure, but it allows for easy fine-tuning, before |
| inch x 5 ft, available as a standard size at a hardware | | | | making something more permanent. |
| store) | | | | Now, turn the fan on and the air coming out should |
| The fan I used is roughly 8 inches in diameter. This | | | | be cooler. For my own unit I measured the exiting air |
| diameter will roughly dictate the size of the opening | | | | as 2-3 degrees Celsius cooler than the air going in (I |
| for the duct (but fan size is not critical). This opening | | | | used a digital kitchen thermometer to measure). The |
| will be made out of pieces of 2x4. | | | | ice in the container should last a few hours, and |
| If you would like to see pictures of the homemade | | | | when you're done you can dump the water down |
| air conditioner with explanation included, then feel | | | | the drain. |
| free to visit my website. The link is at the bottom. | | | | The advantage of this design is that you are utilizing |
| Using the circular saw (making sure to wear eye and | | | | the entire surface area of the metal container to cool |
| ear protection and following safe operating | | | | the air. |
| procedure) cut pieces of 2x4 and nail them together | | | | The dimensions and sizes I used work together |
| to make an 18 inch x 8 inch frame (the external | | | | nicely. But of course, many variations are possible. |
| height is 18 inches, and the opening is 8 inches wide). | | | | Some tips: |
| The aluminum roll will attach to this frame, to form a | | | | · You can put salt (NaCl) into the container |
| spiral duct. | | | | along with the ice. Due to the endothermic reaction |
| To form the spiral duct align the outermost end of | | | | between salt and water, you will get a further |
| the aluminum roll with one of the 18 inch sides of the | | | | lowering of temperature. It may be a useful |
| 18x8 inch frame, such that the inside surface of the | | | | experiment, to see how much salt to add to get a |
| roll touches the side of the frame. Adjust the | | | | target drop in temperature. |
| alignment so that the edges of the roll and frame are | | | | · Setting fan speed on low rather than high |
| flush, and then nail them together. Now, align the | | | | may result in cooler air coming out since the air stays |
| other end of the roll to the other side of the frame, | | | | in contact with the cold container longer. |
| such that the outside surface of the roll touches the | | | | · Well-placed fins inside the duct may help to |
| side of the frame. Once again, make sure the edges | | | | improve the flow and mixing time, thus improving the |
| are flush and nail them together. You should now | | | | amount of cooling. This would be a good project for |
| have a spiral shaped duct. | | | | future work. |
| Next, put the metal container inside the spiral duct, | | | | · In winter you can make blocks of ice |
| adjusting its position and that of the opening so that | | | | outside, and store them in your freezer for when |
| the air blows roughly tangentially past the container | | | | you need them in the summer. I figure that to hold |
| on its way in, and with ample room to exit. Now, fill | | | | you over on those really hot days you need around |
| the container with cold water and put a lot of ice in | | | | 30 ice blocks, each 4x4x8 inches, and one block for |
| it. The temperature of the water should drop to a | | | | each sitting. Remember, this is free ice and you won't |
| few degrees above freezing. The outside of the | | | | be loading your freezer. |