造林木之高週波／抽眞空乾燥

High-frequency Dielectric Power/Vacuum Drying of Plantation Wood

熊如珍(Ju-Chen Hsiung) ； 翟思湧(Sy-Yung Jai)

《台灣林業科學》 14卷2期 (1999/06) Pp. 177-186

https://doi.org/10.7075/TJFS.199906.0177

摘要

高週波／抽眞空乾燥係將高週波加熱與抽眞空合併使用的乾燥法，本研究旨在探討高週波／抽眞空乾燥之乾燥效能。特以台灣主要造林樹種中之檸檬桉(Eucalyptus citriodora)、香楠(Machilus zuihoensis)及樺木(Zelkova formosana)為試材，分別進行傳統窯乾及高週波／抽眞空乾燥。試驗結果顯示：高週波／抽眞空乾燥方法無法用同樣乾燥條件以乾燥檸檬桉、香楠及櫸木，亦即不同樹種以此法乾燥時，在乾燥溫度、眞空度及乾燥時間上有其各自適用的基準。高週波／抽眞空乾燥檸檬桉及香楠木材其乾燥速率均明顯大於傳統窯乾者，顯示高週波／抽眞空乾燥方法對提高木材乾燥速率確有效益。高週波／抽眞空乾燥檸檬桉、香楠及櫸木，均發生長度方向乾燥不均勻之現象。乾燥後檢視最後含水率其表、心層之均勻程度，僅檸檬之高週波／抽眞空乾燥不及傳統窯乾者，香楠及櫸木之兩種乾燥方法其均勻程度趨於一致。乾燥後檢視木材表、心層含水率，高週波／抽眞空乾燥三樹種均係心層大於表層，與傳統窯乾者之結果一致，顯示高週波／抽眞空乾燥均非自內至外，而是與基於傳統窯乾者一般，乃自外至內。

關鍵字

高週波／抽眞空乾燥 ； 檸檬桉 ； 香楠 ； 櫸木

並列摘要

This study evaluates the effects of high-frequency/vacuum (HFV) drying on plantation wood of Eucalyptus citriodora, Machilus zuihoensis, and Zelkova formosana. Drying schedules in the conventional kiln were T3-C2 for Eucalyptus citriodora, T8-D4 for Machilus zuihoensis, and T6-B3 for Zelkova formosana. Drying schedules in the HFV kiln used drying temperatures of 42-45℃. At the same time, a vacuum of up to 20-60 ton was placed on the chamber. The results of this study indicate that: adequate drying temperature of the HEV kiln was not the same drying temperature of 42-45℃. Lumber in the HFV kiln dried faster than did lumber in the conventional kiln. As to moisture content distribution along the Length of the board, moisture content changed from the end to the middle of the board, not being uniform in HFV kiln-drying. Moisture distribution across the hoard thickness showed a tendency, after drying, for the moisture content to be lower at the outside than the inside of the hoards. Thus, the lumber did not dry ”from the inside out”, but dried in basically the same manner as occurs in conventional kiln-drying, from the outside in.

並列關鍵字

high-frequency/vacuum drying ； Eucalyptus citriodora ； Machilus zuihoensis ； Zelkova formosana