氣液二相流體於突擴十字聚焦型微流道利用界面活性劑增進傳輸穩定性之研究

Effects of surfactant concentration on bubble transport in a double forcing microchannel with sudden expansion

吳政蒲(Cheng-Pu Wu)

指導教授 ： 潘國隆

國立臺灣大學/工學院/機械工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.01249

摘要

本研究主要探討雙十字聚焦微流道與界面活性劑，應用於氣泡傳輸穩定性，及微氣泡載體技術上之可行性。研究主要分為三大部分：(1)利用新型雙十字聚焦 (double forcing microchannel, DFM) 之結構，嘗試在改變不同氣液流量比及流體界面活性劑濃度下，維持氣泡粒徑大小，以符合微氣泡載體技術之條件；(2)藉由方形突擴流場，使氣泡減速、碰撞、形變甚至發生破裂的現象，分析不同界面活性劑濃度對於氣泡傳輸穩定性之影響；(3)藉由漸擴型微流道及對衝型微流道，驗證氣泡表面阻力效應，及氣泡間薄膜流動效應對氣泡傳輸及穩定性之影響。研究中發現，DFM結構確實能夠克服傳統氣泡產生機制之限制，使氣泡於不同流場條件下維持其尺寸。此外，添加低濃度的界面活性劑於研究中確實有助於防止氣泡產生結合、形變，及破裂之現象，提升氣泡之傳輸穩定性，但此效應會隨著界面活性劑濃度之提高而逐漸下降。研究最後，藉由漸擴型微流道及對衝型微流道，排除氣泡間運動之複雜性，對高濃度下界面活性劑所產生之效應做更進一步之探討及驗證。

關鍵字

界面活性劑 ； 雙十字聚焦流道 ； 突擴流道 ； 氣泡結合 ； 微氣泡載體

並列摘要

In the present work, the stability of bubble transportation and application of delivery agent with microbubbles, were studied.
The research was categorized into three parts: (1) To investigate the surfactant effect on bubble deformation, a new device, double forcing microchannel (DFM) was designed to maintain the bubble size in desired surfactant concentration; (2) Analyzing the surfactant concentration effect on bubble transportation, by investigation of bubble coalescence, rupture, and bubble deformation in sudden expansion; (3) Using a diverging microchannel and a set of counter-flow microchannesl to prove the effect of drag force and film flow on bubble surface at high concentration of surfactants.
The result showed that the limitations of traditional microbubble generators could be overcome by applying the DFM device. The bubble size could be maintained at different gas-liquid flow ratios and surfactant concentrations. Furthermore, the coalescence, rupture, and deformation of bubbles could be prevented by lowering the concentration of surfactant. This effect was reduced when the surfactant concentration in the liquid became higher. In the final part, to demonstrate the effect of drag force and film flow on the bubble surface at high surfactant concentration, the bubble motions are to be studied in a diverging microchannel and a set of counter-flow microchannels, whereby the complexity is reduced.

並列關鍵字

Surfactant ； double forcing microchannel ； sudden expansion ； bubble coalescence ； microbubble agents

參考文獻

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