| 摘要 |
Lumber is dried in a kiln by controlling the temperature and humidity of air within the kiln during a first cycle, followed by a second cycle allowing humidity to equalize between the coarse and dense lumber in the kiln without adding further energy. Air recirculates across the lumber in the kilm, and the drop in dry bulb air temperature across the lumber indicates the dryness of the lumber. The air temperature within the kiln is maintained at a predetermined setpoint, but no attempt is made to control the temperature drop across the lumber. Upon reaching a predetermined temperature drop across the lumber, corresponding to a relatively high amount of moisture in the kiln, no further energy is supplied to the kiln and air recirculation continues for a time to allow equalization of moisture in all lumber within the kiln. The process yields a desired uniform amount of moisture in the lumber while avoiding overdrying of the relatively coarse lumber in the kiln.
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