Fundamental Investigations for Very High Heat-Flux Innovative Operations of Milli-Meter Scale Flow Boilers

CBET-1402702高热通量去除在许多关键应用中至关重要，例如电子冷却或数据中心冷却（电子处理器或组件产生的热量必须快速消散以保持其可靠工作）。去除热量的最有效的方式之一是通过相变过程，例如在集成在发热装置的背面上的冷却通道中沸腾。在电子应用中，热量通常在芯片级产生，并且由于尺寸小，由于蒸汽阻塞通道以及通道中的不稳定性，会出现显着的功能和沸腾效率问题。拟议的研究将集中在通过确保加热表面上的薄连续蒸发膜来克服效率问题的方法上。这些方法的成功开发将确保提高计算机和电子设备的可靠性，并实现更密集的封装和更小的footprint.For拟议的研究，预计在两个阶段（液体和蒸汽）的外部施加的脉动下的高热流能力。由于脉动，薄且波状的沸腾液体膜出现，并且覆盖整个热交换表面。研究将证实，通过适当调整平均准稳态膜厚分布（在没有脉动的情况下）以及沿着叠加波的振幅控制（通过控制施加脉动的振幅），是否可以沿流动锅炉的长度沿着获得高的热通量值。这是预期的，因为波谷附近的液膜流动动力学由接触线流动物理学主导，该接触线流动物理学导致波谷“粘滞/停留”。“靠近热交换表面。因此，在所提出的脉动操作下，在大多数位置处，平均液膜厚度将显著减小，并且对流效应（在热交换表面与液体-蒸气界面之间的液体流动中）将同时增加。

CBET-1402702High heat flux removal is of critical importance in a number of key applications such as electronic cooling or data center cooling (where heat generated by electronic processors or components have to be rapidly dissipated to keep them working reliably). One of the most effective ways of removing heat is through a phase change process such as boiling in cooling channels integrated on the back side of the heat-generating device. In electronic applications, the heat is typically generated at the chip-level, and due to the small sizes, significant functionality and boiling efficiency problems arise due to the vapor blocking the channel, and instabilities in the channel. The proposed research will focus on methods that will overcome the efficiency issues by ensuring a thin continuously evaporating film on the heated surface. Successful development of these methods will ensure improved reliability of computer and electronic devices and enable denser packaging and smaller footprint.For the proposed study, high heat-flux capabilities are expected under externally imposed pulsations in the two phases (liquid and vapor). Thin and wavy boiling liquid films arise as a result of the pulsations, and cover the entire heat-exchange surface. Investigations will confirm if one can achieve high heat-flux values along the length of the flow boiler by a suitable adjustment of the mean quasi-steady film thickness profile (in the absence of pulsations) along with amplitude control of superposed waves (by controlling the amplitude of imposed pulsations). This is expected because the liquid film flow dynamics near the wave-troughs are dominated by the contact-line flow physics which causes the wave-troughs to "stick/dwell?" near the heat exchange surface. Therefore, under the proposed pulsatile operations, at most locations, the mean liquid film thickness will be significantly reduced and convection effects (in the liquid flow between the heat-exchange surface and the liquid-vapor interface) will be concurrently increased.