Collaborative Research: Very High Heat-flux Cooling through Stable Energy-Efficient Macro-scale Partial Flow-boiling Using Microstructured Surfaces and Ultrasonics

各行各业对高功率密度电子设备的迫切需求，迫切需要高效且经济的冷却解决方案。一种有前景的方法是利用先进且稳定的流动沸腾工艺，采用具有接近大气压的低沸点温度（40-50摄氏度）的环境友好的电介质流体，以及最大允许芯片温度和冷却电介质流体之间的相对小的操作温度差。该项目将通过在高热通量（50 - 200 W/cm 2或更高）下采用高度稳定和节能的Novec/3 M工程流体部分流动沸腾来展示有效的冷却策略。所提出的方法将涉及充满流体的微结构表面，这些表面经历特殊的结构和子结构微纳米尺度振动，消耗非常少量的能量。这种方法的一个有吸引力的好处是产生明显更高压力的蒸汽（比其他方法多2-3倍），从而能够从冷却热交换器回收大量的废热：当扩展到大型系统（例如数据中心）时，允许这些现象回收大部分废热（例如，拟议的研究将利用毫米级散热器中部分流动沸腾的稳定节能冷却性能，该散热器具有流体填充的微结构沸腾表面，用于增强核态沸腾（ENB）。该提案将通过利用由子结构的压电诱导超声微振动引起的声热效应来实现非均匀成核气泡内的显著且可持续的蒸发速率（即，频率为1-10 MHz的网线;振幅：nm/µm范围），在100至10，000 Hz的声波频率下叠加振幅调制，并产生µ m级振幅。声波频率将促进有效和共振的结构微振动，交替地增强液体再润湿和从微结构沸腾区域去除微气泡，允许它们过渡到散热器内的宏观尺度两相流。因此，ENB将通过共振和节能结构和子结构微振动的协同组合来实现。此外，这种方法引起的额外加热将在蒸汽中产生高压，可以利用这些高压来开发新的废热回收技术。因此，这一提议有可能为高功率密度设备开发新型节能和环保的冷却解决方案，以及改进废热回收的策略，将在数据中心和混合动力汽车市场中具有重要的应用。此外，该项目将促进大学与产业的合作，通过学生指导促进人力资源开发，并有助于促进该领域的多样性和包容性。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The urgent demand for high power-density electronic devices in various industries has created a pressing need for efficient and cost-effective cooling solutions. One promising approach is the utilization of advanced and stable flow-boiling processes, employing environmentally friendly dielectric fluids with low boiling temperatures (40-50 deg C) near atmospheric pressures, and relatively small operating temperature differences between the maximum allowable chip temperatures and the cooling dielectric fluid. This project will demonstrate an efficient cooling strategy by employing highly stable and energy-efficient partial flow-boiling of Novec/3M-engineered fluids at high heat fluxes (50 - 200 W/cm2 or more). The proposed approach will involve fluid-filled microstructured surfaces that undergo special structural and sub-structural micro-nano-scale vibrations, consuming very small amounts of energy. An attractive benefit of this approach is the generation of significantly higher pressure vapor (2-3 times more than other approaches), enabling significant waste heat recovery from cooling heat exchangers: allowing these phenomena, when scaled to large systems (such as data centers), to recover a large portion of the waste heat (e.g., 200 TWh globally from data centers alone) as clean electricity.The proposed research will leverage the stable energy-efficient cooling performance of partial flow-boiling in a millimeter-scale heat sink with a fluid-filled microstructured boiling surface for enhanced nucleate boiling (ENB). This proposal will deliver on achieving significant and sustainable vaporization rates within the heterogeneously nucleated bubbles by leveraging the acoustothermal effects caused by piezo-induced ultra-sonic micro-vibrations of the sub-structures (i.e. of mesh wires at frequency: 1-10 MHz; amplitude: nm/µm range), with superposed amplitude modulations at sonic frequencies ranging from 100 to 10,000 Hz and resulting in µm-scale amplitudes. The sonic frequencies will promote efficient and resonant structural micro-vibrations, alternately enhancing both liquid rewetting and the removal of micro-bubbles from the microstructured boiling region, allowing them to transition into the macro-scale two-phase flow within the heat sink. Hence, ENB will be achieved through the synergistic combination of resonant and energy-efficient structural and sub-structural micro-vibrations. Furthermore, the additional heating induced by this approach will generate high pressures within the vapor that can be harnessed to develop new waste heat recovery technologies. This proposal, therefore, with the potential to develop novel energy-efficient and environment-friendly cooling solutions for high-power density devices as well as strategies for improved waste heat recovery will have significant applications in data centers and the hybrid electric vehicle market. Furthermore, the project will foster university-industry collaborations, facilitate human resources development through student mentoring, and contribute to promoting diversity and inclusiveness within the field.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.