Flow and Heat Transfer Characteristics of Hydrophobic and Hydrophilic Microchannel Flow

疏水和亲水微通道流动的流动和传热特性

• 批准号: 16560174
• 负责人: SUZUKI Yuji
• 金额: $ 2.37万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16560174/
• 关键词: Microchannel; Functional Solid Interface; Hydrophobic and Hydrophilic Wall; Two Phase Flow; Flow Characteristics; Bursting of Liquid Film; 撥水性固体壁面; 親水性固体壁

Characteristics of single and two-phase flow in hydrophobic and hydrophilic microchannels were investigated in the laminar flow range. The hydrophobic microchannel was made by a glass tube coated with a silicone. Drag reduction did not occur in degassed tap water flowing in pipes with the smooth hydrophobic surface by measuring the pressure drop. Experiments in two-phase flow (nitrogen and tap water) were carried out to measure the total pressure drop and the flow pattern by using a microscope and a high-speed VTR system. For small liquid flow rate, total pressure drop in the hydrophobic microchannel was much higher as compared with the normal channel. That flow pattern was small liquid and gas segments flowing in the pipe without liquid film. The separation and adhesion of the liquid on the solid wall at both ends of liquid slug, caused larger drag than the slug flow with liquid film. Meanwhile, in the hydrophilic surface, a bursting of liquid film is expected to be hard to arise. The hydrophilic microchannel two-phase flow is more expectative for a drag reduction than the hydrophobic channel. However, it was too difficult to make a hard photocatalytic TiO_2 coating inside of a microchannel for a hydrophilic surface.

在层流范围内研究了疏水和亲水微通道中单相和两相流的特征。疏水微通道是由涂有硅树脂的玻璃管制成的。通过测量压力下降，在带有光滑的疏水表面流动的脱气自来水中不会发生阻力减少。进行两相流（氮和自来水）中的实验，以使用显微镜和高速VTR系统来测量总压降和流动模式。对于较小的液体流量，与正常通道相比，疏水微通道的总压降要高得多。该流量模式是小液体，气体段在没有液体膜的管道中流动。液体在液体slug的两端的固体壁上的分离和粘附，比用液体膜的Slug流动更大。同时，在亲水性表面，预计很难出现液体膜的爆发。与疏水通道相比，亲水性微通道两相流对阻力减少的期望更高。然而，对于亲水性表面的微通道内部的硬催化TiO_2涂层来说是太困难了。