Experimental Studies of Solar and Solar-Dehumidification Lumber Drying

A 1.2-m highly efficient and economical solar kiln, heated with external solar collectors built from recycled aluminum beverage cans, has been designed and constructed to dry green lumber to 15% moisture content. Yellow-poplar lumber was effectively 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% to 67%, respectively, and drying times were 2 to 3/2 times faster than air drying. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. During winter operation the solar-dehumidification system was able to dry green lumber down to 8% moisture content in 18 days. Also, energy consumption and time to dry to 15% moisture content was less with solar-dehumidification drying than with just solar drying.