Abstract Thermal management of high-power electronics requires cooling strategies capable of dissipating high heat fluxes while maintaining the device at low operating temperatures. Two-phase jet impingement offers a compact cooling technology capable of meeting these requirements at a low pressure drop. Generally, confined impingement geometries are used in electronics cooling applications, where the flow is constrained between the hot surface and orifice plate. Understanding the primary heat transfer mechanisms occurring as boiling takes place on the surface during jet impingement is important, specifically under such confined conditions. In this study, heat transfer from a copper surface is experimentally characterized in both confined jet impingement and pool boiling configurations. The dielectric liquid HFE-7100 is used as the working fluid. For the jet impingement configuration, the jet issues through a single 2 mm-diameter orifice, at jet exit velocities of 1, 3, 6, and 9 m/s, into a confinement gap with a spacing of 3 jet diameters between the orifice and heat source. Additional orifice-to-target spacings of 0.5, 1, and 10 jet diameters are tested at the lowest (Vj = 1 m/s) and highest (Vj = 9 m/s) jet velocities. By incrementing the heat flux applied to the surface and observing the steady-state response at each flux, the single-phase and two-phase heat transfer performance is characterized; all experiments were carried through to critical heat flux conditions. The jet impingement data in the fully boiling regime either directly overlap the pool boiling data, or coincide with an extension of the trend in pool boiling data beyond the pool boiling critical heat flux limit. This result confirms that nucleate boiling is the dominant heat transfer mechanism in the fully boiling regime in confined jet impingement; the convective effects of the jet play a negligible role over the wide range of parameters considered here. While the presence of the jet does not enhance the boiling heat transfer coefficient, the jet does greatly increase single-phase heat transfer performance and extends the critical heat flux limit. Critical heat flux displays a linear dependence on jet velocity while remaining insensitive to changes in the orifice-to-target spacing.

中文翻译：

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确定在受限两相射流冲击过程中作为主要传热机制的核沸腾

摘要 大功率电子设备的热管理需要能够消散高热通量同时将设备保持在低工作温度的冷却策略。两相射流冲击提供了一种紧凑的冷却技术，能够在低压降下满足这些要求。通常，受限冲击几何形状用于电子冷却应用，其中流动在热表面和孔板之间受到限制。了解在射流冲击期间在表面发生沸腾时发生的主要传热机制很重要，特别是在这种受限条件下。在这项研究中，铜表面的传热在受限射流冲击和池沸腾配置中进行了实验表征。电介质液体 HFE-7100 用作工作流体。对于射流冲击配置，射流以 1、3、6 和 9 m/s 的射流出口速度通过一个直径为 2 mm 的孔口进入限制间隙，孔口和射流直径之间的间距为 3 个射流直径。热源。在最低 (Vj = 1 m/s) 和最高 (Vj = 9 m/s) 射流速度下测试了 0.5、1 和 10 个射流直径的额外孔口到目标间距。通过增加施加到表面的热通量并观察每个通量下的稳态响应，表征了单相和两相传热性能；所有实验都进行到临界热通量条件。完全沸腾状态下的射流冲击数据要么直接与池沸腾数据重叠，要么与池沸腾数据趋势超出池沸腾临界热通量限制的扩展一致。该结果证实，在约束射流冲击中，在完全沸腾状态下，核沸腾是主要的传热机制；射流的对流效应在此处考虑的广泛参数范围内发挥的作用可以忽略不计。虽然射流的存在不会提高沸腾传热系数，但射流确实大大提高了单相传热性能并扩展了临界热通量限制。临界热通量显示出对射流速度的线性依赖性，同时对孔口到目标间距的变化不敏感。虽然射流的存在不会提高沸腾传热系数，但射流确实大大提高了单相传热性能并扩展了临界热通量限制。临界热通量显示出对射流速度的线性依赖性，同时对孔口到目标间距的变化不敏感。虽然射流的存在不会提高沸腾传热系数，但射流确实大大提高了单相传热性能并扩展了临界热通量限制。临界热通量显示出对射流速度的线性依赖性，同时对孔口到目标间距的变化不敏感。