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Build Yourself A Solar Dryer
An Iowa farmer dries his corn for 1 1/2 cents a bushel, using a home-made solar collector mounted on an old mobile home chassis. "I wouldn't dry corn any other way," says Calvin Colony, of Oxford. "What other way can you dry a bushel of 31% moisture corn down to 17% for a cent and a half?"
Colony's collector, pictured here, is 8x24 ft. x 8 in. deep and is baffled so that air moves up and down around the baffles on its way through the collector and into the 8,000-bu. bin of corn. An 8 hp fan pulls air through the collector and into the grain. Colony claims he has achieved air temperatures as high as 170 degrees F.
The lowan farms 320 acres and raises corn which he feeds to livestock. He stores and feeds through the winter, and says he can get by with the 17% moisture. "Bringing corn on down another 2 points would be the most difficult part of my drying procedure," he says. "A small electric heating element would be of great help."
His homemade collector, built with the help of an Iowa State University professor, cost $200 when it was built three years ago. It is made of aluminum, painted black and shaped into fins, glass, foam insulation, and wood. It is mounted on the chassis of a burned-out mobile home, and the aluminum is pop cans cut open and flattened out. He used glass rather than fiberglass because he feels it is more efficient for letting in the sun's rays.
The advantage of the mobile home chassis is three-fold: (1) The collector is portable; (2) It can be tilted, using concrete blocks, to face the sun directly; and (3) The collector face can be turned away from the sun for summer, which is necessary to protect it.
Temperature of the air from the collector differs, depending on the position of the sun in the sky, which changes during the day and from month to month. Colony says that during the winter months, when the sun is at a lower angle, the solar collector will produce warmer air. Also, he says, humidity in the air can reduce the temperature.
He likes to use reflector panels on the ground in front of the collector to increase the amount of heat obtained. Also, he uses a grain stirring system in his grain bin to, aid in the drying process and to retard grain spoilage.
"Solar-dried grain is like crib-dried grain," says Colony. "It's a deeper yellow; no cracking or grain damage occurs with solar drying. It's better quality grain."
He lists these disadvantages of his system:
• Time to dry is long. Last year it took 21 days to dry 6,000 bushels.
• A collector is needed for each bin.
• High winds can damage a collector.
Some do's and don'ts include:
• Don't try to pull all the air from drying through the collector, just enough to pick up the heat. It takes too much electricity to pull all the air through the 120 ft. collector and attached tubes.
• Do use break-resistant glass instead of fiberglass.
• Do use pop cans cut open. "Aluminum 'was invented to collect and dissipate heat, and aluminum cans are cheap."
• Do put baffles in the collector so that the air doesn't bypass some of the heat as it moves through.
• Do put the collector on a mobile home trailer frame.
• Don't let the collector face the sun in summer as it can get too hot.
• Don't turn off the fan, because it takes all night to cool off the collector and all day to heat it up. Corn seems to dry faster if you heat and cool it repeatedly.
For more information, contact: FARM SHOW Followup, Calvin Colony, Rt. 2, Oxford, Ia. 52322 (ph 319 645-2831).


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1980 - Volume #4, Issue #5