- 學位論文
以模擬探討定子-轉子旋轉盤反應器之流力行為
Simulation on fluid flow behaviour in a rotor - stator spinning disk reactor
摘要
定子-轉子旋轉盤反應器(rotor-stator spinning disc reactor, RS-SDR)是製程強化中新穎的裝置，具有良好的熱、質傳反應，並可調控流體於反應器內的滯留時間，因此本研究以模擬探討RS-SDR之流力特性，透過商用計算流體力學(Computational Fluid Dynamics, CFD)軟體Fluent 14.0以二維軸對稱對RS-SDR進行模擬，最後與文獻的實驗結果進行比較，進一步確認模擬與實驗間的誤差值，以確信CFD軟體模擬之可信度。 於模擬中，探討單相流體於改變通道寬度、轉速、進料流率等操作變因對流動型態的影響。由結果得知，增加轉速及進料流率皆可使流體速度提升，而壓降也隨著進料流率及轉速提升而增加。其次探討兩相流體於轉速、液體進料流率、氣體進料流率、空腔區(cavity zone)之徑向距離變化對反應器內流動的影響，由結果顯示，液體於上層通道主要流態分為塊狀流(slug flow)及液膜流動，隨著轉速提高，可改善氣體於空腔區的累積，並有助於氣體在下通道中形成小氣泡流動。此外將模擬結果與文獻之壓降、速度分布在相同的操作條件下進行比較，得到模擬之壓降值較實驗值高，但是模擬的壓降與速度分布之結果則與文獻中的趨勢相似。 由改良模型的結果得知，加上貫穿轉盤的流體分布通道，能改善氣體於空腔區之堆積，使下通道中容易出現破碎的小氣泡。根據實驗結果，以利未來於反應器性質研究上有明確的方向。
並列摘要
Rotor-stator spinning disc reactor (RS-SDR) is a novel equipment which has high heat and mass transfer efficiency for process intensification. In this study, the characteristics of hydrodynamics of the device were investigated by simulation. A commercial Computational Fluid Dynamics (CFD) software, Fluent 14.0, was used in the simulation. The simulation results were compared with the experimental results in references to confirm the reliability of the CFD model. The influences of the rotor-stator distance, the rotational speed, and liquid flow rate were investigated. The results showed that both the radial and the circumferential velocities increased with increasing the rotational speed and the liquid flow rate. Likewise, the pressure drop increased as the liquid flow rate and the rotational speed increased. Next, the influence of the rotational speed, the liquid flow rate, the gas flow rate, and the size of cavity zone were investigated in the two-phase flow system. According to the result, two types of liquid flow, i.e., slug flow and film flow, were found in the upper channel of the RS-SDR. Because of high centrifugal force, the accumulation of gas can be reduced in the cavity zone and small gas bubbles size were generated between the rotor and the bottom stator. Besides, the simulation results of the flow behavior of liquid and the pressure drop were compared with the experimental results in references under the same operating conditions. Even though the simulated pressure drop is higher than that in reference, the trends of the simulated pressure drop and velocity distribution were similar to the experimental ones. Finally, several designs of RS-SDR were tested. The results showed that the accumulation of gas in cavity zone can be effectively decreased by using perforated disc which contributes to easily forming small gas bubbles in the bottom channel. According to the experimental results, the optimization design of the RS-SDR is capable of being investigated in the future work.