微通道内液液两相流压力降的测量和关联

摘要

In microchannel, the pressure drop of liquid-liquid two-phase flow is of vital importance for intensifying heat and mass transfer of the flow system. In the present work, liquid-liquid two-phase flow in rectangular microchannels with two different aspect ratios (400μm×600μm and 400μm×800μm) was recorded by using a high-speed camera, and the pressure drop under slug flow regime was measured by using a differential pressure sensor. The cyclohexane was used as the dispersed phase and distilled water with 0.3%SDS(sodium lauryl sulfate) as the continuous phase. The results show that the pressure drop increases with the increases of the flow rates of both phases, the capillary number Ca, the Reynolds number Re and the viscosity of the continuous phase, and decreases with the increase of the velocity ratio of both phases. When Ca>0.015 or Re > 20, the pressure drop increases with the increase of the aspect ratio of the microchannel. A modified correlation for homogeneous flow model was proposed for predicting pressure drop under slug flow regime of liquid-liquid two-phase flow in microchannels, and the calculated results show good conformity to the experimental data.%　　微通道内液液两相流的压力降对系统内部热量和质量传递具有重要影响。针对环己烷-含0.3%SDS(十二烷基硫酸钠)蒸馏水液液两相系统，利用高速摄像仪对2种不同深宽比的矩形截面直管微通道内的液液两相流进行了实时观测和记录，用压差变送器测定了其在弹状流型下的压力降。微通道尺寸(深度×宽度)分别为400μm×600μm，400μm ×800μm。结果表明：弹状流型下的压力降随系统各相流率、毛细数、雷诺数、连续相黏度的增加而增加，随两相速度比值的增加而减小，且当毛细数 Ca>0.015或雷诺数 Re>20时，压力降随着通道截面深宽比的增加而增加。基于实验结果，修正了均相流模型，提出了新的压力降预测关联式，模型计算结果与实验值吻合良好。