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性和亲水性微通道中单相流和两相流的特性。疏水性微通道由涂有有机硅的玻璃管制成。通过测量压降，在具有光滑疏水表面的管道中流动的脱气自来水没有发生减阻。进行了两相流（氮气和自来水）实验，使用显微镜和高速 VTR 系统测量总压降和流型。对于小液体流量，疏水微通道中的总压降比正常通道高得多。该流动模式是小的液体和气体段在没有液膜的管道中流动。液塞流两端固体壁上的液体分离和粘附，产生比液膜段塞流更大的阻力。另一方面，在亲水性表面中，预计难以发生液膜破裂。亲水微通道两相流比疏水通道更有望实现减阻。然而，在微通道内部制备亲水表面的硬质光催化TiO_2涂层非常困难。