臺灣博碩士論文加值系統

本篇論文主要針對木材進行乾燥脫水之研究，而乾燥方式主要分為四種，分別為熱風乾燥、真空乾燥、微波加熱乾燥及真空微波加熱乾燥等四種方式，並進行乾燥速率比較及乾燥後木材的應力與應變比較。實驗結果發現，一般所使用的熱風乾燥方式所需的乾燥時間最長，乾燥至12﹪的含水率約需花費8~10小時，而微波加熱乾燥方式所花的乾燥時間約比熱風乾燥方式快72倍的時間，乾燥至12﹪的含水率約7~12分鐘。而真空微波加熱乾燥方式所花的時間又比微波加熱乾燥方式短，乾燥至12%的含水率約為5~9分鐘，這是因為在真空狀態下木材內部的水分子有由內部往外部移動的趨勢，因此比在大氣環境下進行微波加熱的木材乾燥速率快1.2倍左右。在這四種乾燥方式中以真空乾燥法所需花費的時間最長，花費30分鐘進行乾燥後，其木材含水率仍高達83﹪，效果並不理想。在應力測試上運用熱風乾燥方式其含水率到達12﹪時，木材所能承受的應力較運用微波及真空微波加熱方式要好，這是因為運用微波加熱的方式，木材由於內部受到微波加熱引起高溫，當木材內部的水分含量低於一定值後，將會發生燃燒現象，導致內部結構受損，所能承受的應力也會大大的減小，因此使用微波加熱方式時宜注意導入微波的功率與加熱時間的長短。

This paper studied drying and dehydration of timber. The four drying methods included heat drying, vacuum drying, microwave heating drying, and vacuum microwave heating drying. The drying speed, the stress and strain of the timber after drying were compared. The experiments found that heat drying required the longest drying time; using the method to dry to 12% water content required 8-10 hours. The drying time required for microwave heating drying was 72 times shorter than heat drying; using the method to dry to 12% water content required 7-12 minutes. The drying time required for vacuum microwave heating drying was shorter than microwave drying; using the method to dry to 12% water content required 5-9 minutes. The reason was that in a vacuum environment, the water molecules inside the timber had outward movement trend. Thus, the drying speed of microwave heating was 1.2 times faster in atmospheric environment. Of those four methods, vacuum drying required the longest time. After 30 minutes of drying, the water content was 83%. The result was unsatisfactory. In stress tests, when the water content was 12% under heat drying method, the stress bearable to the timber was better than that of microwave and vacuum microwave heating methods. The reason was that when the timber was heated microwave, the temperature rise started from the inside. When the water content of the inside of the timber reduced to a specific level, ignition may occur and led to damage to the internal structure, and the bearable stress would reduce significantly. Therefore, attention should be paid to the power of microwave and the heating time length when using microwave heating method.

摘要
ABSTRACT
誌謝
目錄
表目錄
圖目錄
第一章 緒論
1.1研究背景
1.2文獻回顧
1.3研究目的
第二章 研究方法
2.1微波技術簡介
2.2微波加熱原理
2.3實驗數學模式
第三章 實驗設備
3.1熱風乾燥設備
3.2真空乾燥設備
3.3真空微波/微波加熱乾燥設備
3.4其他儀器介紹
第四章 操作說明及實驗步驟
4.1熱風機台操作程序
4.2真空乾燥機台操作程序
4.3真空微波加熱機台操作程序
4.4實驗步驟
第五章 結果討論
5.1微波系統性能測試
5.2木材溫度分佈量測
5.3乾燥速率測試
5.4木材應力試驗
第六章 結論及建議
參考文獻
符號彙編

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