Department of Mechanical Engineering , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States.
Department of Mechanical Engineering , Yonsei University , Seoul 03722 , Republic of Korea.
Nano Lett. 2018 Oct 10;18(10):6392-6396. doi: 10.1021/acs.nanolett.8b02747. Epub 2018 Sep 5.
We present a new concept of a structured surface for enhanced boiling heat transfer that is capable of self-adapting to the local thermal conditions. An array of freestanding nanoscale bimorphs, a structure that consists of two adjoining materials with a large thermal expansion mismatch, is able to deform under local temperature change. Such a surface gradually deforms as the nucleate boiling progresses due to the increase in the wall superheat. The deformation caused by the heated surface is shown to be favorable for boiling heat transfer, leading to about 10% of increase in the critical heat flux compared to a regular nanowire surface. A recently developed theoretical model that accounts for the critical instability wavelength of the vapor film and the capillary wicking force successfully describes the critical heat flux enhancement for the nanobimorph surface with a good quantitative agreement.
我们提出了一种新的结构化表面概念，用于增强沸腾换热，该表面能够自适应局部热条件。由两个热膨胀系数相差很大的相邻材料组成的自由支撑的双晶纳米结构能够在局部温度变化下发生变形。由于壁面过热度的增加，随着核沸腾的进行，这种表面会逐渐变形。实验结果表明，受热表面的变形有利于沸腾换热，与常规纳米线表面相比，临界热流密度提高了约 10%。最近提出的一个理论模型考虑了蒸汽膜的临界不稳定性波长和毛细抽吸力，成功地描述了双晶纳米结构表面的临界热流密度增强，具有很好的定量一致性。
