| 摘要: | 在本文中，我們開發了一種製造微模型的方法，和以前的製程比較起來，製造過程更加容易且使用的設備和材料不這麼昂貴，而製造出來的微模型具有2.5D的流道結構，流道中的垂直結構不是單純的平面，而是有著凹凸的複雜結構，和2D微模型相比，我們的微模型可以更好地代表真實多孔介質，能夠更真實的表現出流體在真實多孔介質中的流動現象。我們將塑膠片材以及雙面膠結合後，使用CNC(Computer Numerical Control)銑削機加工流道，因為材料的透明度很高，僅需要將流體染色後，就可以輕鬆看出流體的流況，且染色流體會在厚度不同的地方，顏色呈現不同的深淺，可以輕易地在複雜的微模型中觀察並且分析，無須透過其他複雜的儀器就能完成結果。
我們製作了單層、四層、八層模型來進行汲取(imbibition)和汲取-排退(imbibition-drainage)實驗。汲取實驗是將濕潤項流體(乙醇)注入模型將非濕潤項流體(空氣)排出，而汲取-排退實驗則是在汲取實驗之後，再注入非濕潤項流體(空氣)將濕潤項流體(乙醇)排出。完成模型之後利用軟管和注射泵浦連結，我們使用"3 μl" ⁄"min" 、6 "μl" ⁄"min" 、60 "μl" ⁄"min" 、150 "μl" ⁄"min" 和300 "μl" ⁄"min" 共五種流率來注入乙醇，比較汲取和汲取-排退實驗中的乙醇飽和率差別。
首先，乙醇在較薄的微模型中可以深入到流道孔隙中，而隨著微模型厚度的增加，乙醇開始只能在微模型的邊緣流動，只能填滿微模型中的角落區域無法填充整個流道，因此乙醇飽和度開始逐漸下降。而在相同厚度的微模型中，乙醇的毛細數較小時，只能夠在邊緣以角偶流的方式進行，而在毛細數逐漸增大後，才開始以完整的流體介面移動並填滿流道。而在相同厚度但內部流道形狀改變時，即使在汲取實驗後有著相同的乙醇飽合度，但空氣被限制在流道中的位置也完全不同，就可以看出流道形狀的簡化，對於流體的流動狀況會有很大的影響。
;In this study, we have developed a method for micromodels fabrication. Compared with the previous process, the fabrication is easier to manufacture and the equipment and materials used are less expensive. The micromodel produced has a 2.5D channel structure, and the vertical structure in the channel is not a simple plane, but a complex structure with irregularities. Compared with 2D micromodels, our micromodels can better represent real porous media and can more realistically show the fluids flow in real porous media. After bonding the plastic sheet and the double-sided tape, we use the CNC (Computer Numerical Control) milling machine to process the channel. Because of the high transparency of the material, it is easy to see the fluid flow after only dyeing the fluid. The dyeing fluid will show different color depths in different thicknesses of micromodels, which can be easily observed and analyzed in complex micro-models without the need to go through other complicated instruments.
We made single-layer, four-layer, and eight-layer micromodels for imbibition and imbibition-drainage experiments. The imbibition experiment is to inject the wetting phase fluid (ethanol) into the model to discharge the non-wetting phase fluid (air). In the imbibition-drainage experiment, after the imbibition experiment, to inject non-wetting fluid (air) to discharge the wetting phase fluid (ethanol). Then we use "3 μl" ⁄"min" , 6 "μl" ⁄"min" , 60 "μl" ⁄"min" , 150 "μl" ⁄"min" and 300 "μl" ⁄"min" flow rates for experiment.
First, ethanol can flow into the deep pores of the channel in a thin micromodel. With the increase of the thickness of the micromodel, ethanol can only flow at the edge of the micro-model and fill the corner regions in the micromodel, so the ethanol saturation decreases. In the same thickness micromodel, when the capillary number of ethanol is small, corner flow movement dominates ethanol flow in micromodels and most of the air was trapped at narrow pore throats. After the capillary number is gradually increased, bulk meniscus movement dominates ethanol flow in micromodels, the air trapped in the dead-end pores. At the same thickness but the shape of the internal channel is changed, even if the same ethanol saturation we obtained after the imbibition experiment, the position of the air trapped in the channel is completely different. We can know that the simplification of the shape of the flow channel has a great influence on the flow state of the fluid. |
