The Study of Pool Boiling Heat Transfer with Different Square Sized Microstructures

• Main Authors: Jhih-Yu Lai, 賴祉妤
• Other Authors: Tsung-Chie Cheng
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/6aw8u7

碩士 === 國立高雄應用科技大學 === 機械與精密工程研究所 === 100 === Anisotropic etching on (100) silicon chip surface. An experimental is etched on the silicon chip surface with the same array， and change the size of the artificial cavities diameter of square micro-structure， and discuss the size of the square micro-structure of artificial cavities diameter on silicon chip surfacec to chage superheat temperature and critical heat flux (CHF). An experimental study was performed to investigate the nucleate boiling and critical heat flux (CHF) of FC-72 dielectric liquid on hydrophilic square micro-structure silicon chip surface by the cost-effective and simple micro-structure silicon chip technique. The utility of boiling heat transfer is characterized by two parameters: (i) heat transfer coefficient (HTC) or the material thermal conductance; (ii) the CHF limit that demarcates the transition from high HTC to very low HTC. While increasing the CHF and the HTC has significant influence on system-level energy efficiency， safety， and cost， their values for dielectric fluids FC-72 have essentially remained unchanged for many decades. The 4cm2 hydrophilic square micro-structure silicon chip surfaces with different active artificial cavities radius and large size artificial cavities was utilized in saturated pool boiling tests with wetting dielectric fluid FC-72， and its performance was compared to that of a silicon chip surface. The results showed the artificial cavities diameter size of 15μm and 100μm increased CHF by 17.4% and 34% for FC-72， respectively， and boiling performance enhancement are dependent on the level of wettability improvement. In addition， the nucleate boiling heat transfer coefficient (HTC) of artificial cavities diameter size on silicon chip surface appeared higher than that of silicon chip surface. Because a high surface tension force offered by liquids in silicon chip surface provides an additional mechanism for boiling enhancement.