Droplet impact dynamics and transient heat transfer of a micro spray system for power electronics devices
Droplet impact dynamics and transient heat transfer of a micro spray system for power electronics devices
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DOI：
10.1016/j.ijheatmasstransfer.2015.08.099
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发表时间：
2016
影响因子：
5.2
通讯作者：
S. Hsieh;Sueng-Yang Luo
中科院分区：
文献类型：
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作者：
S. Hsieh;Sueng-Yang Luo
研究了恒定热流(0.1~0.9W/cm2)加热下，多股水流冲击抛光表面时的瞬时换热和液滴冲击动力学，适用于电力电子设备的热结构设计。采用商用压电雾化板(功率为11.5W，频率为104kHz)，分别采用dj=9.7μm、10μm和35μm三种不同的喷嘴阵列，分别获得了质量流量分别为4.42×10−5 kg/S、1.11×10−4 kg/S和1.15×10−4 kg/S的多重喷雾。利用一种由氧化铟锡薄膜(∼200 nm)和厚度为0.3 mm的石英玻璃组成的超薄加热器来表征冷却过程和液滴撞击流体力学。通过底视光学可视化，测量和提取了瞬时冲击液滴的形貌和表面温度分布，得到了液膜的演化厚度。研究了喷嘴直径、喷雾高度和初始表面温度对极短时间内的换热的影响(<；1，S)。此外，还对所得到的∼-1和S的瞬时冷却性能和换热系数进行了确定和讨论。
We present a study on the instantaneous heat transfer and droplet impact dynamics caused by multiple streams of water impinging on a polished surface with a constant heat flux (0.1–0.9 W/cm2) heating applicable to power electronics’ thermal configuration design. A multiple spray was produced by a commercial piezoelectric atomization plate (power = 1.5 W and frequency 104 kHz) with three different nozzle arrays ofdj= 7 μm, 10 μm and 35 μm and a corresponding mass flow rate of 4.42 × 10−5kg/s, 1.11 × 10−4kg/s and 1.15 × 10−4kg/s, respectively. A heater consisting of an ultra-thin layer (∼200 nm) of Indium Tin Oxide (ITO) combined with quartz glass (0.3 mm thickness) substrate was used to characterize the cooling history and droplet impact hydrodynamics. Through optical visualization from a bottom view, the transient impact droplets’ morphology and the, surface temperature distribution, were measured and extracted to obtain the evolved film thickness. The effects of nozzle diameter, in addition to the spray height and the initial surface temperature on heat transfer for very short periods of time (<1 s), were studied. Furthermore, the resultant transient (∼1 s) cooling performance and heat transfer coefficient were secured and discussed.