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内的单相和两相流动特性。疏水微通道由涂有硅酮的玻璃管制成。通过压降测量，除气自来水在光滑疏水表面的管道中没有发生减阻。利用显微镜和高速VTR系统对两相流（氮气和自来水）进行了总压降和流型的测量。在液体流速较小的情况下，疏水微通道内的总压降要比普通通道大得多。这种流动模式是小的液体和气体在没有液膜的管道中流动。液体在液塞流两端固壁上的分离和粘附，比液塞流有液膜时产生更大的阻力。同时，在亲水表面，预计很难产生液膜的破裂。亲水微通道两相流比疏水微通道更能减少阻力。然而，在亲水表面的微通道内制备硬光催化TiO_2涂层过于困难。