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中国物理学会期刊

表面材质对介电液体气泡成核及沸腾换热的微观影响机理

CSTR: 32037.14.aps.74.20250398

Microscopic influence mechanism of surface material on nucleation and boiling heat transfer of dielectric liquid bubbles

CSTR: 32037.14.aps.74.20250398
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  • 基于介电液体的两相换热技术已成为大功率电子器件高效热管理的可行方案之一. 然而, 受表面材质和工质热物理性质影响, 介电液体实际应用中存在显著沸腾滞后现象, 进而影响沸腾换热性能. 由于气泡起始成核空间和时间尺度较小且气相压力在相变过程显著波动, 宏观实验和模拟方法仍存在一定局限性. 本研究结合非平衡分子动力学和机械控压方法, 研究R1336mzz(Z)液膜在不同加热表面材质(铜原子、铝原子和硅原子)下的气泡成核及沸腾换热规律. 同时, 从声子振动态密度和势能约束两个方面讨论了介电液体的异相成核机理. 一方面, 以铜原子为代表的高固-液相互作用力、低频振动(<10 THz)表面材料在初始加热阶段可产生较大界面热通量(0.216 × 109 W/m2)且能在壁面附近吸引大量液相分子, 但不可避免提高了起始成核势垒. 另一方面, 相较铝表面(振动重叠度0.151)以硅原子为代表的弱固-液相互作用力、中高频振动表面材料可与介电液体产生合理的声子振动耦合(振动重叠度0.349)以桥接界面热输运, 并降低液膜所受势能约束, 有助于推动局部液体簇形成气泡胚核.

     

    Two-phase heat transfer technology utilizing dielectric liquids has emerged as one of the efficient solutions for thermal management in high-power electronic devices. However, in practical applications, due to the interfacial materials and thermophysical properties, dielectric liquids exhibit significant boiling hysteresis, which in turn affects the boiling heat transfer performance. Owing to small spatial and temporal scales of bubble nucleation initiation, macroscopic experiments and traditional simulation methods still face certain limitations. In this study, non-equilibrium molecular dynamics and mechanical pressure control method are utilized to investigate the bubble nucleation and boiling heat transfer characteristics of R1336mzz(Z) liquid film on different heating surface materials (i.e. copper atoms, aluminum atoms, and silicon atoms). Additionally, the heterogeneous nucleation mechanism of dielectric liquid is discussed from two perspectives: phonon vibrational density of states and potential energy restriction. On the one hand, surface materials, represented by copper atoms, with high solid-liquid interaction forces and low-frequency vibrations, can generate substantial interfacial heat flux and attract a large number of liquid-phase molecules near the heated wall. However, such materials inevitably increase the energy barrier of bubble nucleation. On the other hand, surface materials, represented by silicon atoms, with weak solid-liquid interaction forces and medium-to-high-frequency vibrations can achieve reasonable phonon vibrational coupling with dielectric liquid to bridge interfacial thermal transport. Such materials can reduce the potential energy restriction on the nanofilm, thus facilitating the formation of local liquid clusters into bubble nuclei. These findings can provide a comprehensive understanding of the underlying mechanisms of bubble nucleation and heat transfer in dielectric liquids, and thus offer valuable insights into thermal management enhancement strategies in high-power electronic devices.

     

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