Abstract:

Saturated flow boiling experiments were conducted to investigate the influence of surface wettability on the hydraulic and thermal transport performance in a large width-to-height aspect ratio, one-sided heated rectangular microchannel with deionized water as the working fluid. The superhydrophilic surface is fabricated through the Plasma Enhanced Chemical Vapor Deposition (PECVD) method on the originally smooth hydrophilic silicon wafer. The contact angles of the silicon wafer and superhydrophilic surface deposited with 100 nm-thickness silicon dioxide thin film are 65° ±3° and less than 5° respectively. Effects of heat flux and mass flux on the heat transfer characteristics for the superhydrophilic and silicon wafer surface are discussed through experimental measurements, which are further explained by flow patterns observed through high speed visualization. The local heat transfer coefficient decreases first until approaching a minimum value and then increases towards the exit along the flow direction. Severe heat transfer deterioration is obtained for the bare silicon wafer surface with increased heat flux, resulting from the local dryout phenomenon as can be verified by the flow visualization. Improved heat transfer performance is obtained on the superhydrophilic surface for relatively low mass fluxes and high heat fluxes as a result of latish occurrence of the local dryout phenomenon.

摘要：

以去离子水为工质，针对高宽高比的矩形微细通道内竖直向上的饱和流动沸腾进行了实验研究。利用等离子增强化学气相沉积工序在原本光滑亲水的硅片表面上沉积100 nm厚度的二氧化硅薄膜得到超亲水表面。通过实验测量探讨了热通量、质量流量对超亲水和普通表面换热特性的影响，并进一步通过高速摄像对观察到的两相流型结合换热进行解释。结果表明超亲水表面在低流速和高热通量下可以通过延缓局部干涸的发生从而强化换热。