真空乾燥是一種可於相對低溫運作的乾燥法，許多熱敏感性物料如食物、藥品或其他具生物活性的物質皆適用真空乾燥。此乾燥法在傳統上皆以真空幫浦來移除真空腔體內因乾燥過程而產生的水汽，但真空泵浦的運作相當耗能，而且容易連帶地將細小的乾成品排至大氣環境中，所以本團隊應用溴化鋰吸收式冷凍系統的原理，來設計一組溴化鋰吸濕及脫水系統，此系統可連續地在真空下吸收水汽，並可將所吸收的水汽排除至真空腔體外。
　　本團隊所建立的吸濕/排汽系統包括概念設計、軟體程式的模擬與分析、實驗設備的製作與組裝，以及吸濕/排汽功能的測試，而本文的重點在運用其中數值模擬的結果來設計實驗設備的幾何尺寸與材料選用，並確保腔體真空度的維持，來達到吸濕/排汽的連續性。
　　在輔助提升吸濕效能的實驗上，本研究以兩種不同的冷卻水排管(平滑管與鰭片管)進行吸濕實驗，實驗結果在總熱傳率上，鰭片管較平滑管提升了8%~35%；而總吸濕率方面，鰭片管則較平滑管提升了16%~21%。

Vacuum drying can be operated at a relatively low temperature and is one of a few drying methods which can be applied for drying the temperature-sensitive materials such as health foods, drugs and other bio-active materials. To maintain a low pressure inside the vacuum chamber, the vaporized steam is usually expelled out by a vacuum pump. Since the specific volume of vapor is very large (about 40000 times of liquid water), the operation energy for a pump is very energy intense. In addition, the very fine dried product may be entrained into the exhausted system flow and loss to (or contaminate) the environment. There for, our research team used the concept from lithium bromide absorption chiller to create an absorber/desorber system, which can continuously absorb the vaporized steam inside the vacuum chamber and desorbs it outside the chamber.
The construction of this absorber/desorber system includes conception design, system simulation and analysis by a computer code, manufacture and setup of a test facility and the functional test of absorption/desorption processes. In this thesis, the focuses are placed on the configuration design of experimented facility and the material selection for system components in order to maintain a low pressure environment inside the vacuum chamber and to achieve the continuity of absorption/desorption processes.
To assist in promoting the absorption capacity, the absorption tests carried out in this study used two different kinds of cooling tube; one without fin and the other with plat-fin connected vertically along a tube array. The test results indicated that the heat transfer rate and the vapor absorption rate of finned tube were respective about 8~35% and 16~21% higher than that of plain tube.

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