In this paper, we present an experimental investigation of pool boiling heat transfer on multiscale (microano) functionalized metallic surfaces. Heat transfer enhancement in metallic surfaces is very important for large scale high heat flux applications like in the nuclear power industry. The multiscale structures were fabricated via a femtosecond laser surface process (FLSP) technique, which forms self-organized mound-like microstructures covered by layers of nanoparticles. Using a pool boiling experimental setup with deionized water as the working fluid, both the heat transfer coefficients and critical heat flux were investigated. A polished reference sample was found to have a critical heat flux of 91 W/cm2 at 40 °C of superheat and a maximum heat transfer coefficient of 23,000 W/m2 K. The processed samples were found to have a maximum critical heat flux of 142 W/cm2 at 29 °C and a maximum heat transfer coefficient of 67,400 W/m2 K. It was found that the enhancement of the critical heat flux was directly related to the wetting and wicking ability of the surface which acts to replenish the evaporating liquid and delay critical heat flux. The heat transfer coefficients were also found to increase when the surface area ratio was increased as well as the microstructure peak-to-valley height. Enhanced nucleate boiling is the main heat transfer mechanism, and is attributed to an increase in surface area and nucleation site density.
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机译：在本文中，我们对多尺度（微/纳米）功能化金属表面上的池沸腾传热进行了实验研究。金属表面的传热增强对于像核电行业这样的大规模高热通量应用非常重要。通过飞秒激光表面处理（FLSP）技术制造了多尺度结构，该技术形成了自组织的丘状微结构，被纳米颗粒层覆盖。使用去离子水作为工作液的池沸腾实验装置，研究了传热系数和临界热通量。发现抛光的参考样品在40°C的过热下的临界热通量为91 W / cm 2 ，最大传热系数为23,000 W / m 2 K.经处理的样品在29°C下的最大临界热通量为142 W / cm 2 ，最大传热系数为67,400 W / m 2 K.发现临界热通量的增加与表面的润湿和芯吸能力直接相关，其起到补充蒸发液体并延迟临界热通量的作用。还发现，当表面积比增加以及微观结构峰谷高度时，传热系数也会增加。增强的核沸腾是主要的传热机制，并且归因于表面积和成核位点密度的增加。
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