Abstract Flow boiling of dielectric fluids in microchannels is one of the most desirable cooling solutions for high power electronics. However, the flow boiling of dielectric fluids is hindered by their unfavorable thermophysical properties. Specifically, without precooling dielectric fluids, it is challenging to promote critical heat flux (CHF) due to its high vapor density, low surface tension and the resulted superior wettability. In this study, each side wall of a five-parallel silicon microchannel array was structured with an array of microscale reentry cavities and four micronozzles bypassed by an auxiliary channel. The present microchannel configuration aims to significantly enhance CHF of HFE-7100 flow boiling by improving global liquid supply using auxiliary channels and micrononozzles as well as by sustaining liquid film using capillarity induced by reentry cavity array. Equally important, these structures can promote nucleate boiling at low heat flux, generate intense mixing, and promote thin film evaporation at high heat flux, resulting in high flow boiling heat transfer rate. Flow boiling of HFE-7100 in the present microchannel configuration is characterized with mass flux ranging from 231 kg/m2 s to 1155 kg/m2 s. The effective two-phase heat transfer coefficients (HTCs) are ranging from 6 kW/m2 K to 117 kW/m2 K. Compared to the four-nozzle plain-wall microchannels, for example, the effective HTC and CHF can be substantially enhanced up to 208% and 37%, respectively, without escalating pressure drop at a mass flux of 462 kg/m2 s. Compared to plain microchannels with inlet restrictors, CHF is considerably enhanced up to 70% with a reduction of pressure drop ∼82% at a mass flux of 1155 kg/m2 s. Significantly reduced pressure drop is achieved by integrating bypass and the enhanced confined bubble removal. A peak CHF value of 216 W/cm2 is achieved at mass flux of 2772 kg/m2 s in the present microchannel configuration with inlet temperature at room temperature.

中文翻译：

---

HFE-7100 在集成有多个微喷嘴和再入微腔的硅微通道中的流动沸腾

摘要 微通道中介电流体的流动沸腾是大功率电子设备最理想的冷却解决方案之一。然而，介电流体的流动沸腾受到其不利的热物理性质的阻碍。具体而言，在没有预冷介电流体的情况下，由于其高蒸汽密度、低表面张力和由此产生的优异润湿性，提高临界热通量 (CHF) 具有挑战性。在这项研究中，五平行硅微通道阵列的每个侧壁都由一组微型折返腔和四个被辅助通道绕过的微喷嘴构成。本微通道配置旨在通过使用辅助通道和微喷嘴改善整体液体供应以及使用由再入腔阵列诱导的毛细管作用维持液膜来显着增强 HFE-7100 流动沸腾的 CHF。同样重要的是，这些结构可以在低热通量下促进成核沸腾，产生强烈混合，并在高热通量下促进薄膜蒸发，从而产生高流动沸腾传热速率。本微通道结构中 HFE-7100 的流动沸腾特征在于质量通量范围为 231 kg/m2 s 至 1155 kg/m2 s。有效的两相传热系数 (HTC) 的范围从 6 kW/m2 K 到 117 kW/m2 K。例如，与四喷嘴平壁微通道相比，在 462 kg/m2 s 的质量通量下，有效 HTC 和 CHF 可以分别显着提高至 208% 和 37%，而不会增加压降。与带有入口限流器的普通微通道相比，在 1155 kg/m2 s 的质量流量下，CHF 显着提高了 70%，压降降低了 82%。通过集成旁路和增强的受限气泡去除来实现显着降低的压降。在入口温度为室温的本微通道配置中，在 2772 kg/m2 s 的质量通量下实现了 216 W/cm2 的峰值 CHF 值。通过集成旁路和增强的受限气泡去除功能，可显着降低压降。在入口温度为室温的本微通道配置中，在 2772 kg/m2 s 的质量通量下实现了 216 W/cm2 的峰值 CHF 值。通过集成旁路和增强的受限气泡去除来实现显着降低的压降。在入口温度为室温的本微通道配置中，在 2772 kg/m2 s 的质量通量下实现了 216 W/cm2 的峰值 CHF 值。