|
Hi All, Last year a friend was having problems with moisture ruining his plasma cutter torch. I designed a small air dryer that worked well to cure this problem. The basic design is a CU tubing coil inside of a tank of fluid used as a heat exchanger. Water works in non-freezing areas and anti-freeze for freezing areas. Keep the tank as cool as possible, out of the sun, away from shop heat, etc. Air from the compressor is fed into the top of the heat exchanger where the chill from the water causes condensastion to form inside the exchanger thus droppping the condensasate to a "U" trap at the bottom of the heat exchanger where the moisture is removed via a automatic water drain valve. Use a coil of 3/4" CU tubing. Stretch that coil out and install spacer bars on 3 sides of the coil to where the coils are seperated a 1/4" or better. A piece of 1/2" rigid CU pipe would work well to keep the coils seperate as well as hang the exchanger from the top of the tank or as feet on the bottom of the tank. At the bottom of the coil bend a "U" trap. At the bottom of the "U" install a drip leg. I would think a couple 90º elbows and a "T" would also work to make the "U". Install a automatic water drain on the drip leg or a ball valve for manual draining. The condensastion drain extends thru the tank side wall to discharge the collected water. The "U" trap must be located at the bottom of the exchanger coil. The air and condensastion pass over the drip leg of the "U" where the water drops into the drip leg to be removed and the air continues to the top of the tank to be connected to the main air supply line. You can use a metal garbage can for the tank as that also supply's a lid to keep trash out of the cooling tank. The drain fitting can be welded to the tank. The colder the tank water is the more moisture that will be removed from the air. Under most conditions for a common air supply for a home shop, the ideal air temperature discharge is 45ºf to remove 100% of the moisture. That would mean a typical tank water temperature would have to be about 40º to allow for exchanger inefficiency. There's too many calculations to post for every possible air tempature and humidity conditions. I tried to figure a good general ball park area to work with and that was 45º to 55º coolant tempature. You can also add ice in the tank for summer time use. Just freeze 1gal jugs of water and sit them in the tank then refreeze as needed. During the summer it would be a benefit to wrap the tank with insulation to keep tank heat gain to a minimum. Also I would use a small amount of anti-freeze in the cooling water to keep the tank and coils as clean as possible. Clean equals a higher heat transfer ratio. So does it work? He stated he sees zero moisture at the last filter drain where before he was seeing alot of mositure at this filter. You can also use a old refrigerator to run the heat exchanger coil thru. I still suggest the liquid heat exchanger as it's more efficent than a air to air exchanger. Just remember that the "U" trap has to be at the lowest point of the system. T_Bone
| 
