臺灣博碩士論文加值系統

本研究分析重質氣體在一維管柱中之傳輸參數及流通量，然為補充先前鄭(2011)傳輸實驗中所欠缺之擴散係數而進行雙氣體擴散實驗，製作孔隙率為0.3676之乾燥海砂管柱，以與傳輸實驗的土壤管柱特性一致，並取得氣體在海砂中之擴散參數。分析結果顯示，N2與CO在乾燥海砂中擴散系統之有效擴散係數在8.27×10-6～9.59×10-6 m2/sec間，而N2與SF6系統則為3.65×10-6～4.23×10-6 m2/sec間，這些系統中Knudsen擴散係數則在2.67×10-3～8.89×10-3 m2/sec間。
接下來利用Dusty Gas Model與Fick’s first law理論及使用鄭(2011)的傳輸實驗數據來計算擴散通量及分析討論重力及密度影響的各個傳輸分量。流通量之分析結果顯示，DGM擴散流通量主要由莫耳分率梯度之擴散所主導，但不等莫耳分子量及受重力影響之擴散通量也占有相當的比例，分別最大可佔10%及30%。而DGM與Fick’s first law理論計算出的擴散通量雖有差異，但大致上級數是一致的。黏滯流通量的結果顯示，當傳輸實驗為垂直向上及向下方向傳輸時，重質氣體入口端至土壤管柱五公分處主要受壓力梯度影響黏滯流通量；土壤管柱五至十五公分處則主要由重力所影響。另外，總流通量的結果則受黏滯流通量的影響，兩個理論的計算結果有時會有一個級數的差異。
另外，本研究也以MISER模式(Rathfelder et al.,1997)分析氣體在一維管柱中隨著時間改變的傳輸情形，並與鄭(2011)之傳輸實驗結果比較。結果顯示，其並不完全與實驗趨勢一致，判斷由於MISER求解莫耳分率型式之擴散傳輸方程式，並未包含其他可能影響傳輸通量的因素，如DGM中的不等莫耳分子量產生之擴散通量及受重力影響之擴散通量，故造成實驗與模式結果的差異。而Altevogt et al. (2003)以質量型式傳輸方程式模擬比較其實驗結果的符合度則較本研究為佳，此一結果應待更進一步的研究。

This study analyzes transport parameters and flux components for dense gas transport in a one-dimensional soil column. A binary gas diffusion experiment was firstly conducted for the effective diffusion coefficient in a column composed of dry sea sand with a porosity of 0.3676, similar to the column used in the transport experiment of Cheng (2011). Results show that the effective diffusion coefficient for N2-CO system ranges between 8.27×10-6 and 9.59×10-6 m2/sec；for N2-SF6 system 3.65×10-6 and 4.23×10-6 m2/sec； and the Knudsen diffusion coefficient for air ranges between 2.67×10-3 and 8.89×10-3 m2/sec.
The Dusty Gas Model (DGM) theory and Fick’s first law were then applied to analyze various flux components based on the experimental measurements in Cheng (2011). Results show that the dominant diffusion component is the molar-fracton gradient term in the DGM. However, the nonequimolar and gravity-induced diffusion component can be at most 10% and 30%, respectively, of the total diffusive flux. Magnitudes of the diffusive flux given from two diffusion theories are of the same order. The viscous flux induced by gravity is dominant between the SF6 gas entrance to the soil column and the 5-cm location from the entrance in the soil column. But pressure gradient-induced viscous flux is dominant between 5-cm and 15-cm from the entrance in the soil column. Thus, magnitude of the total flux affected by the viscous one, can be one order of magnitude in difference between these two different theories.
Besides, the time-varied SF6 density in the transport column for the experiment in Cheng (2011) was simlated with a numerical model – MISER developed by Rathfelder et al. (1997), to investigate how the discrepancy between the experimental measurement and the prediction from a Fickian-type, molar based transport equation, used in MISER is. Results show that prediction from the transport modeling with MISER can have great difference from the experiment measurement, especially for systems in vertically upward and downward transport directions, due to the inadequacy of considering diffusion only induced by molar fraction variation. However, Altevogt et al. (2003) used predictions from a mass-based transport equation and compared with in experiment measurements. They showed a result more consistently than ours. This issue needs advanced study in the future.

致謝 I
摘要 II
ABSTRACT IV
目錄 VI
表目錄 V
圖目錄 VI
第一章 緒論 1
1.1 研究背景 1
1.2 研究目的與內容 3
第二章 理論背景與文獻回顧 5
2.1 Dusty Gas Model 5
2.2 Fick’s first law 8
2.3 傳輸方程式 9
第三章 研究方法 11
3.1 傳輸實驗資料 11
3.2 傳輸量計算 17
3.2.1 有效擴散係數 17
3.2.2 內在滲透係數與Knudsen擴散係數 22
3.2.3傳輸流通量 23
3.3 傳輸模式 24
第四章 結果與討論 29
4.1 擴散實驗 29
4.1.1 檢量線 29
4.1.2 雙氣體擴散實驗 32
4.2 傳輸參數 42
4.3 傳輸流通量 45
4.4 暫態傳輸分析 57
第五章 結論與建議 63
第六章 參考文獻 67
附錄 70

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