Page 20 RAIN April/May 1983 Grain Drying Bin Controller Current methods of drying corn for grain consume large amounts of energy. Many com drying bins rely on fans to blow air heated by natural gas or electricity through moist corn. Some farmers reduce fuel costs by using unheated air and manually controlled fans, but unheated, moistureladen air can cause spoilage. Nathan Meyers received a USDOE A.T. Small Grant to design a small, affordable computer controller to increase the efficiency of bin dryers. He is developing the computer hardware and the software necessary for ambient air monitoring and control. Sensors will measure air temperature and relative humidity in the bin, and a microprocessor will activate a supplemental heating system when ambient air has too much humidity to dry the corn. In order to test and monitor the grain drying bin controller, Meyers hopes to find a site by this summer. He is looking for a corn drying bin with electrically controllable heat (gas or electric source). The site should have an indoor desk near the bin to house the computer and printer and a person who will periodically observe the system. The location may be either east or west of the Cascade Mountains. The monitoring will take place over one drying period, beginning this fall. "This could be a genuine breakthrough,” notes Meyers. "In agriculture, computers are now used to keep financial records and aid farm management. This is revolutionary in that it would be tried as an actual controller of an agricultural process; it holds a lot of potential for new applications in energy-cost reductions.” (Nathan Meyers, 655 S.E. Bridgeway, Corvallis, OR 97333) Greenhouse/Animal Shelter Ecosystem Central Oregon’s growing season lasts just three short months or less. The air is dry, with the sun shining more than 300 days a year. Communities are dispersed and depend on distant food and fuel suppliers. Planning to lengthen the growing season to ten months or more, Bruce Withers of Sisters has used his grant to construct an integrated animal shelter and passive solar greenhouse from which he is collecting light, temperature, and relative humidity data. The greenhouse avails itself of unique, climateenhancing techniques. Heat is stored in 12 inch-deep rock walkways, five gallon clear plastic containers filled with dark blue water—situated below the elevated container beds to keep roots and soil warm—and a special Trombe wall. The wall separates the animal shelter from the greenhouse, absorbing heat from the greenhouse during the day. Warm air passes through large openings at the top of the wall into the shelter. At night, the wall radiates heat both to the greenhouse and to the animal shelter. Heat generated by the animals and their waste products is transferred through the upper wall vents to the greenhouse by natural convection. As the air cools in the greenhouse, it drops and returns to the animal shelter through the lower wall vents. The double glazing is insulated with roll-down window quilts at night. Ground-level vents in the south wall foundation and bamboo shades reduce summer temperatures. A thermally operated electric fan turns on at temperatures above 80 degrees. Withers has also planted Jerusalem artichokes and sunflowers along the southern and western walls for additional shading. The goats and chickens present at night contribute two other valuable "fuels” to the greenhouse: carbon dioxide and humidity. The shelter collects carbon dioxide-rich air at night, gently "leaking” it to the plants during the day. Since the air around Sisters is quite dry, the added 10 percent humidity produced from the animals breathing and waste product evaporation encourages plant growth. "This integrated design will extend the growing season considerably,” says Withers. "We hope to grow greens and root crops throughout the winter.” Sunlight, temperature, humidity, energy-use data, construction cost, and growing methods data will be available this fall. (Bruce Withers, P.O. Box 928, Sisters, OR 97759) Withers
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