Kidus Guyea, Vivek Manepallia, Baris Dogruozb, and Damena Agonafera
aMechanical Engineering, University of Maryland, College Park, MD, United States of America
bRivos inc., Santa Clara, CA, United States of America
For more information about this article and related research, please contact Prof. Damena Agonafer.
Abstract:
With the advancement of artificial intelligence (AI) applications, there is a growing demand for sophisticated and powerful chips. The adoption of these processors, along with increased power and bandwidth, highlights the necessity for efficient thermal management solutions. In this context, advanced two-phase thermal management systems have emerged as promising solutions. This study introduces a novel direct-to-chip evaporative cooling (DCEC) device that uses hollow micropillars integrated with a liquid delivery system to enable microscale evaporation of water and dielectric coolants in a fully actively pumped system. The device can operate in different evaporative regimes, characterized by a concave meniscus inside the micropillar’s hole or a droplet confined at the inner or outer edge of the micropillar, depending on the heating power, thermophysical properties of the coolant, and operating pressure. To characterize the heat transfer performance of the DCEC, we conduct a comprehensive numerical analysis, varying different operating and design parameters for water, R-1336mzz(Z), and Opteon™2P50. Our numerical results demonstrate device-level heat fluxes of 575 W/cm2, 413 W/cm2 , and 365 W/cm2 for water, R-1336mzz(Z), and Opteon™2P50, respectively. The corresponding heat transfer coefficients are 2.88 × 105 W/m2 K, 2.07 × 105 W/m2 K, and 1.83 × 105 W/m2 K for water, R-1336mzz(Z), and Opteon™2P50, respectively. We also examine the performance of the device across various operating regimes. The results show that the device achieves 1.33× and 3.1× greater heat flux when a droplet is suspended at the outer edge of the hollow micropillar, compared to the stages with a concave or convex meniscus inside the micropillar’s hole. We here conduct a detailed pressure analysis to understand the hydrodynamic characteristics of the device and determine the required inlet pressure for different coolants, operating regimes, and heat loads. These inlet pressure conditions can be integrated into the design of a feedback loop system to mitigate system failures caused by flooding or dryout.
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