The fabrication of a single glass microchannel to study the hydrophobicity effect on two-phase flow boiling of water

Abstract

Hydrophobicity is an important parameter in a microscale two-phase thermal hydraulic system because the interfacial force has an influential role in this system. Previous research has been limited to the two-phase flow regime, with most results indicating that the surface hydrophobicity is an influential parameter. However, the hydrophobicity effect on flow boiling has not been studied, especially at the microscale. This is due to the coupled difficulties of the fabrication of the microchannel and the modification of its surface. This study develops the methods for the fabrication of a single glass microchannel and the formation of a hydrophobic surface. The flow boiling experiment in the microchannel is conducted using deionized water. The visualization of two-phase flow patterns was carried out using a high-speed camera and a long-distance microscope. Very clear images were obtained due to the high transparency of the microchannel material. Local dry patches were observed in the liquid film of elongated bubbles and a new flow pattern was found with the hydrophobic surface.