臺灣博碩士論文加值系統

超低溫系統通常使用二元冷凍系統(Cascade)，可降低壓縮比，由於分別兩段所使用的壓縮機體積可變小，相對其耗功變小，達到節能的效果，且可輕易達到系統之操作溫度，因此，本論文利用市售二元超低溫冷凍系統，進行硬體設計、控制策略及冷媒搭配，達到此系統設計的合宜的運轉條件。由於原系統壓縮機及控制電路故障，因此，以相近排氣量之壓縮機取代，並用傳統電路取代機板電路及填充高溫段冷媒A+B與低溫段冷媒A+B，使二元冷凍系統能夠穩定降溫且達到需求溫度，在完成研製冷凍系統後庫內溫度降溫至設定值，且系統以穩定及維持庫內溫度方式下進行測試，分別以庫內溫度-60℃、-70℃、-80℃及-80℃增加負載來測試，之後運轉穩定後取兩小時的溫度及壓力數據並繪制壓焓圖計算冷凍系統效能，結果二元冷凍系統運轉-60℃時的效能為2.31、-70℃的效能為1.07、-80℃的效能為0.84及-80℃增加負載的效能為1.78，但考慮降至-80℃增加負載的降溫過程中所需時間經計算後其效能為0.33。

The Cryogenic systems use cascade system, thus reducing the compression ratio. As the volume of the compressors in two stages is decreased, the wasted work is reduced relatively, so that the energy can be saved, and the system operating temperature can be reached easily. Therefore, this study used the cascade refrigeration system available on the market for hardware design, control strategy and refrigerant collocation, in order to meet the appropriate operating conditions of this system design. Due to the faults of the original system compressor and control circuit, the compressor with similar discharge capacity was used instead, and the board circuit was replaced by traditional circuit. The hot section refrigerant A+B and cold section refrigerant A+B were filled in, so that the cascade system could meet the required temperature and stability. After the refrigeration system was completed. The chamber temperature was cooled to setting value, and then tested the performance of the system under the stable and maintained chamber temperature. The load was increased at the chamber temperature of -60℃, -70℃, -80℃ and -80℃ for testing. Afterwards, the temperature and pressure data in two hours stable operation were taken and the pressure-enthalpy chart was drawn to calculate the performance of refrigeration system. The results showed that the performance of cascade system in operation at -60℃ was 2.31, the performance at -70℃ was 1.07, the performance at -80℃ was 0.84 and the performance with additional load at -80℃ was 1.78, however, considering the time required in the process of cooling to -80℃ the cascade system performance was 0.33.

摘　要 .........................................i
ABSTRACT .........................................ii
誌　謝 .........................................iv
目　錄 .........................................v
圖目錄 .........................................vii
表目錄 .........................................x
第一章 緒論 ...............................1
1.1研究背景 ...............................1
1.2文獻回顧 ...............................2
1.3研究目的 ...............................3
第二章 cascade系統原理說明 .....................4
第三章 實驗系統架構及實驗方法 .....................8
3.1實驗系統架構 ...............................9
3.1.1低溫段 ...............................12
3.1.2高溫段 ...............................17
3.2 控制系統 ...............................23
3.3實驗儀器 ...............................24
3.4實驗方法與步驟 ...............................30
第四章 結果與討論 ...............................32
4.1運轉溫度-60℃ ...............................35
4.2運轉溫度-70℃ ...............................38
4.3運轉溫度-80℃ ...............................43
4.4運轉溫度-80℃及增加負載 .....................46
4.5運轉溫度-80℃及增加負載降溫效能分析 ...........49
第五章 結論與未來建議 .....................51
5.1結論 .........................................51
5.2未來建議 ...............................52
參考文獻 .........................................53

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