流體流過黏彈性凝膠粒子床之理論與實驗研究

Theoretical and Experimental Studies of Fluid Flow through Viscoelastic Gel Particle Bed

林昱燊(Yu-Shen Lin)

指導教授 ： 童國倫

中原大學/工學院/化學工程研究所/碩士(2008年)

https://doi.org/10.6840/cycu200800157

摘要

在諸多工業的分離程序中，常會遇到流體流過可變形多孔介質的輸送現象，但可變形粒子與剛性粒子的堆積行為迥異，很難以傳統剛性粒子的理論來描述，故須適當的修正理論及推衍出新的經驗模式來描述流體流過可變形粒子床的流體力學行為。
本研究以理論和實驗的方式來探討流體流過黏彈性凝膠粒子床的流體力學行為。當流體流過凝膠粒子床時流體的拉曳力會造成孔隙度減少進而導致阻力上升的現象，本研究首先以計算流體力學來比較剛性粒子床與可變形粒子床的流動行為差異，並探討可變形粒子床中的水力壓力和拉曳力；再以單一軸向壓縮實驗量測得可變形粒子其有效比表面積與孔隙度的關係。藉由計算流力及單一軸向壓縮實驗所得到的結果，對Ergun方程式中接觸面積、有效比表面積、孔隙度及粒子壓縮後體積的變化進行修正，使之可適用於低孔隙度的可變形粒子床。
最後將修正後的理論方程式與實驗結果比較，以驗證其正確性。研究結果顯示，修正之後的Ergun方程式可估算得不同流速下黏彈性凝膠粒子床的壓降值。

關鍵字

凝膠 ； 壓降 ； 可變形粒子 ； 粒子床 ； 計算流體力學 ； Ergun方程式

並列摘要

The transport phenomenon of fluid flow through compressible porous media is widely encountered in industrial separation processes. However, most efforts have been devoted to describe fluid flow through rigid porous media or media that are composed of rigid materials, little concerned with the fluid flow through porous media that are composed of soft materials.
In this study, the hydrodynamic behaviors of fluid flow through particles bed composed of viscoelastic gel particles were studied theoretically and experimentally. Effect of particle deformation due to frictional drag and mass of particles on the reduction of porosity was analyzed to examine how this variation led to the increase in flow resistance in the gel particle bed. Computational fluid dynamic (CFD) technique has been adopted to reveal the difference of fluid flow stream in rigid and soft particle beds. The hydraulic pressure and drag force on gel particles were also estimated by CFD calculation. Uni-axial compression experiments have been applied to obtain the relation between effective specific surface area ratio and porosity of a deformable particle bed. Based on the CFD findings and uni-axial compression experimental results, a modified Ergun equation has been derived by considering the variations of contact area, effective specific surface area, porosity and gel particle volume during bed compression.
Finally, theoretical predictions were compared with experimental data of pressure drop to validate the accuracy of the proposed theoretical model. Results showed that the proposed modified Ergun equation could provide accurate steady-state pressure-drop predictions in particles bed composed of viscoelastic gel particles at different superficial velocities.

並列關鍵字

particle bed ； pressure drop ； deformable particle ； Ergun equation ； computational fluid dynamics(CFD) ； gel

參考文獻

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