呂理平臺灣大學：化學工程學研究所徐偉華Shiu, Wei-HuaWei-HuaShiu2007-11-262018-06-282007-11-262018-06-282006http://ntur.lib.ntu.edu.tw//handle/246246/52233本論文在探討有外加磁場作用下，液、固流體化床之流動模式、分散行為與傳統液、固流體化床之差異。流體化床採用內徑0.05 m高約0.75 m壓克力管，固相以平均粒徑274 μm之鐵粒子為磁性粒子，液相為水及濃度分別為0.03 wt%、0.1 wt%與0.2 wt%之CMC(carboxymethyl cellulose)溶液。床體外部利用漆包線纏繞成的兩螺線管來產生穩定的軸向磁場，使其作用於床體內部之粒子。利用壓力轉換器測量所得之單點壓力降對流體速度之曲線圖，來界定各流態間轉變之速度。並且利用追蹤劑技術分析不同流態區域下的軸向分散情況。 　　單點壓降實驗中，藉由Leva法所得鐵砂粒子之最小流體化速度Umf(L)並不會受磁場強度影響；而以Davidson and Harrison法所得之最小流體化速度Umf(DH)則會隨磁場強度上升而增加。磁滯現象的形成即可決定移轉速度Ut(P)，且隨著磁場強度上升而增加。 實驗結果顯示液、固磁流體化床共有四種不同流域，分別為固定床區、過渡區、磁穩定區和不穩定區；由低流速至高流速區分，其間之分隔分別是最小流體化速度Umf(L)、最小流體化速度Umf(DH)與移轉速度Ut(P)。當CMC溶液濃度上升，固定床區、過渡區與磁穩定區的範圍將隨之縮小，而不穩定區即相對擴大。 在軸向分散行為方面，軸向分散係數會隨流體速度上升而增加，而磁流體化床相較傳統流體化床有著較低之軸向分散係數。在使用水(Newtonian)或CMC(non-Newtonian)溶液的磁流體化床中，其軸向分散係數均隨磁場強度增加而下降。此外，磁場影響軸向分散係數的效果隨著CMC溶液濃度提升而逐漸減弱。In this study, the difference of hydrodynamic and dispersion behavior between the liquid-solid magneto-fluidized (0.05 m i.d. × 0.075 m height) bed and the liquid-solid traditional fluidized bed was investigated. The sphere iron particles of 274 μm average diameter were used as the solid phase, water and CMC (carboxymethyl cellulose) (0.03 wt%, 0.1 wt% and 0.2 wt%) solution were used as the liquid phase. A magnetic solenoid coiled by the magnet wire was applied to generate axially magnetic field. The dependency of pressure drop on the velocity was used to establish transition velocities between various regimes. The axial dispersion of various regimes was analyzed by the tracer input-response technique. By Leva’s method, the minimum fluidization velocity Umf(L) was not affect by magnetic force. However, by Davidson and Harrison’s method, the minimum fluidization velocity Umf(DH) was increased with increasing magnetic field intensity. Further more, the transition velocity Ut(P) determined by the hysteresis phenomenon was increased with increasing magnetic field intensity. The experimental results show that there were four flow regimes in a magneto-fluidized bed: fixed bed, transition, magnetically stabilized and unstable regime. The boundaries were minimum fluidization velocity Umf(L), minimum fluidization velocity Umf(DH) and transition velocity Ut(P). When the concentration of the CMC solution increased, the range of fixed bed, transition and magnetically stabilized regime was narrowed down, the unstable regime was enlarged. Both in the magnetic and the traditional fluidized beds, the axial dispersion coefficient was increased with the enhancing fluid velocity. The axial dispersion coefficient of the magnetic fluidized bed was lower than the traditional fluidized bed. The dispersion coefficient of the water (Newtonian) and the CMC solutions (non-Newtonian) both were decreased with the enhancing magnetic field intensity. Besides, the effect of magnetic field on the dispersion coefficient was decreased with the increasing concentration of CMC solution.中文摘要…………………………………………………………………I 英文摘要………………………………………………………………III 目錄………………………………………………………………………V 圖表索引……………………………………………………………VIII 第一章 緒論……………………………………………………………1 第二章 文獻回顧………………………………………………………5 2-1. 磁穩定作用………………………………………………………5 2-2. 液、固磁穩定流體化床之描述和應用…………………………5 2-3. 液、固磁流體化床中最小流體化速度與移轉速度之決定方法10 2-4. 液、固磁穩定流體化床之軸向分散行為………………………18 2-5. 非牛頓流體之相關研究…………………………………………19 第三章 理論背景………………………………………………………21 3-1. 磁性物質之分類…………………………………………………21 3-2. 電流與磁場………………………………………………………21 3-3. 軸向分散係數之預估……………………………………………24 3-3-1 刺激-響應(stimulus-response)法…………………………24 3-3-2 數學工具………………………………………………………25 3-3-3 分散模式(分散住狀流動模式) ………………………………25 第四章 實驗裝置與步驟………………………………………………30 4-1. 實驗裝置…………………………………………………………30 4-1-1 實驗裝置簡介…………………………………………………30 4-1-2 實驗裝置說明…………………………………………………30 4-2. 實驗操作變數……………………………………………………36 4-3. 實驗步驟…………………………………………………………36 4-3-1 單點壓降測量…………………………………………………36 4-3-2 軸向分散實驗…………………………………………………37 第五章 結果與討論……………………………………………………39 5-1. 液、固磁流體化床單點壓降分析………………………………39 5-1-1 磁場對流體化床之作用………………………………………39 5-1-2 磁場對最小流體化速度之影響………………………………45 5-1-3 磁場對移轉速度之影響………………………………………55 5-1-4 非牛頓流體對於最小流體化速度與移轉速度之影響………60 5-2. 液、固磁流體化床之相圖………………………………………66 5-2-1 液、固磁流體化床之區域流態………………………………66 5-2-2 牛頓與非牛頓流體之相圖比較………………………………67 5-3. 液、固磁流體化床之軸向分散實驗……………………………69 5-3-1 牛頓流體之軸向分散實驗……………………………………70 5-3-2 非牛頓之軸向分散實驗………………………………………76 第六章 結果與討論……………………………………………………87 第七章 符號說明………………………………………………………89 第八章 參考文獻………………………………………………………94 第九章 附錄…………………………………………………………100 Appendix 1. NaCl 濃度與電導度之關係…………………………100 Appendix 2. Lab-view 擷取平均壓力數據程式…………………101 Appendix 3. Labview 擷取追蹤劑濃度程式與濃度曲線圖………102 Appendix 4. 軸向分散係數計算方式………………………………104 Appendix 5. CMC 流體之物性………………………………………1051871564 bytesapplication/pdfen-US液固磁流體化床軸向分散係數liquid-solid magnetofluidized bedaxial dispersion coefficientthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/52233/1/ntu-95-R94524080-1.pdf