微细窄通道内纳米线表面的过冷沸腾流动与传热特性  

Flow and heat transfer characteristics of subcooled flow boiling on nanowires surfaces in a narrow microchannel

作　　者：李蔚[1] 李俊业[1] 汪秋刚 邵帅 冯钊赞 Wei Li;Junye Li;Qiugang Wang;Shuai Shao;Zhaozan Feng(Department of Energy Engineering,Zhejiang University,Hangzhou 310027,China;College of Water Conservancy and Civil Engineering,Shihezi University,Shihezi 832000,China;College of Electrical Engineering,Zhejiang University,Hangzhou 310027,China;CRRC Zhuzhou Institute Co.,Ltd.,Zhuzhou 412001,China)

机构地区：[1]浙江大学能源工程学院,杭州310027 [2]石河子大学水利建筑工程学院,石河子832000 [3]浙江大学电气工程学院,杭州310027 [4]中车株洲电力机车研究所有限公司,株洲412001

出　　处：《科学通报》2020年第20期2178-2186,共9页Chinese Science Bulletin

基　　金：浙江省自然科学基金(LY19E060004)资助。

摘　　要：微/纳米结构表面对流动沸腾过程有着显著影响,被应用于高热流的设备散热中.为了进一步探究其物理规律,以去离子水为工质,配合高速摄像观测,研究了截面为0.5 mm×5 mm的矩形微细窄通道内纳米线表面的竖直流动过冷沸腾.一种TiC纳米线的直径约230 nm,高度约4μm;另一种直径约535 nm,高度约12μm.过冷沸腾的质量流量是200和300 kg/(m^2s),过冷度为10 K,热流密度范围是20~200 kW/m^2.分析了不同工况下过冷沸腾的沸腾曲线、平均换热系数和两相流流型.研究发现, 4μm高度纳米线表面的两相换热系数更高,但高热流条件下传热恶化更早. 4μm高度纳米线表面形成了"形成拉长气泡——气泡上下游扩张——局部干涸——流体重新润湿"的周期性两相流型,而12μm高度纳米线表面的流型在高热流下仍以气泡聚合以及形成受限拉长气泡向下游扩张为主.Nowadays, heat dissipation methods of single-phase air cooling or liquid cooling, such as natural convection and forced convection, are unable to meet the high heat flux density dissipated by the heat exchange components of the thermal management system in many relevant fields, such as energy, electronic, and chemical engineering industries. With the recent increase in the power density consumption and miniaturization trend of various equipments, the compactness and efficiency of heat exchangers are becoming increasingly demanding. Compared to conventional channels, heat sinks fabricated using micro-scale channels have a compact structure, higher surface area-to-volume ratio, and heat transfer coefficient, together with less demand for the working fluid and the pumping power supply, which have been gradually paid attention to as remarkable cooling scheme candidates for applications in modern-day and next-generation electronic elements. Recently, the rapid development of the surface modification technology has prompted the development of heat transfer surfaces with micro-or nano-scale structures ranging from a few micrometers to tens of nanometers, which can enhance the boiling heat transfer coefficient and critical heat flux. Therefore, the combination of structured surface and microchannel flow boiling is a highly promoted method of achieving a higher heat transfer performance. Nanowire is one of the micro-structures that can enhance boiling heat transfer. Previous experimental results showed that a nanowirestructured surface could increase the nucleate site density and enhance the capillary wicking process, thereby achieving a higher heat transfer coefficient and a critical heat flux.Herein, TiC nanowires were synthesized on a titanium wafer surface through the electro-deposition method. The diameters of the two types of nanowires were approximately 230 and 535 nm, and their heights were 4 and 12 μm,respectively. The nanowires were staggered and closely arranged on the surface, forming micro-/nano-scaled gaps.

关 键 词：微细窄通道 过冷流动沸腾 纳米线 两相流型 

分 类 号：TK124[动力工程及工程热物理—工程热物理]