Design and Tests of a 500 BF Solar Kiln

Recent shortages and soaring costs of fossil fuels have renewed the interest in using solar energy for lumber drying. A highly efficient kiln, heated with external solar collectors built from recycled aluminum beverage cans, dried lumber to 15 percent moisture content (MC). Yellow-poplar lumber was dried in all seasons of the year in less time by solar kiln-drying than by air-drying. Solar kiln-drying was most effective in the summer and early fall when kiln efficiencies were 90 and 67 percent, respectively, and drying times were two to three and one-half times faster than air-drying. Electrical use in solar-drying was only one-fourth that in kiln-drying. Solar-drying is best suited for small charges (1,000 to 10,000 BF)and when required final MC was more than 12 percent. For lumber that requires lower MC or stress relief, the solar dryer can still serve as a predryer but some of its advantages are obviously lost. The solar kiln, with slight modification, can be used to dry grains and produce, coal slurry, and other industrial products when high temperatures and strict drying schedules are not required.

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