1989 - Volume #13, Issue #4, Page #23[ Sample Stories From This Issue | List of All Stories In This Issue | Print this story | Read this issue]
No Worry Bin Cooler
"I preached for years at Iowa State about keeping an eye on grain in storage. I came up with this idea on my own farm. When you've got a bin full of grain that isn't dried real well, it gets you thinking," says Hull.
His "no worry" system consists of a 1/40 hp. electric squirrel cage fan mounted on a plywood cover that fits over the blower fan on the bin. The small fan draws air out from the plenum chamber under the slatted drying floor at the bottom of the bin, providing at least two air changes per hour in the bin.
"It doesn't dry the corn. It only keeps drawing cool air down through it to prevent air currents in the bin that can cause moisture migration and result in spoilage spots at the center. By keeping air circulating, you keep the temperature down in the bin," says Hull.
Hull simply covered the bin's blower fan with a sheet of plywood and mounted the small blower fan at the center of it (Hull bought the 157 cfm fan from the mail order company W.W. Grainger - ph. toll-free 800 323-0620; in Ill., call 800 225-7149). He covered the fan with a sheet metal cover and then wired it up. Hull stresses that the fan housing must be grounded to the dryer fan housing. The last step was to seal off all openings around the lower part of the bin. He sealed up the opening around the unloading auger with a metal cap and duct tape.
Hull's objective was to change the air twice per hour in the 24-ft. bin. He came up with a simple formula for figuring out how big a fan he needed to do that. He says that about 40% of the space in a bin of corn is free air and a bushel of corn takes up about 1.25 cu. ft. That means a bushel of corn has 1/25 x 0.4 = 0.5 ft. of air space. In a 10,000 bu. bin there would be 0.5 x 10,000 = 5,000 cu. ft. of air space in the stored corn. To get two air changes per hour, you'd need a fan that would move 10,000 cu. ft. per hour. Since most fans are rated by cfm, or cubic feet per minute, you simply divide 10,000 cu. ft. by 60 min a to arrive at 167 cfm.
Hull spent only about $50 to put the low level aeration system together. He recommends turning the small fan on as soon as you shut off the big blower in the fall, and let it run continously. Electric costs run just $10 to $15 per month. He checks the condition of the corn every two weeks or so with a thermometer mounted on a steel rod.
Contact: FARM SHOW Followup, Dale O. Hull, 2925 Ross Road, Ames, Iowa 50010 (ph 515 292-2143).
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