Abstract

The rapid increase in power densities of modern electronic devices necessitates advanced thermal management strategies capable of dissipating ultra-high heat fluxes while maintaining energy efficiency. Building on this need, this work investigates multiple device-level cooling approaches, with a primary focus on the experimental development of direct-to-chip evaporative cooling (DCEC). The DCEC architecture employs a silicon membrane integrated with an array of hollow micropillars that enable intrinsic liquid-vapor phase separation through geometric confinement. This structure sustains stable thin-film evaporation by holding back the liquid while allowing vapor extraction, thereby enhancing heat transfer performance. Complementary theoretical analysis indicates that, with optimized geometry and operating conditions, the platform can achieve heat fluxes exceeding 500 W/cm². Controlled environmental chamber experiments using water demonstrate a background heat dissipation exceeding 220 W/cm² and a heat transfer coefficient of 1.1 x 10⁵ W/m²·K, achieved at a pumping power below 2.3 mW, highlighting the potential for highly efficient thermal management.

To extend applicability toward realistic systems, the DCEC device is further evaluated within a pumped two-phase cooling loop using dielectric refrigerants. A newly designed low-resistance manifold is introduced to support area scaling of the evaporator while minimizing pressure losses. The study characterizes thermal resistance, pressure drop, and operational regimes (evaporation vs flow boiling with vapor venting) across varying heat loads, providing insights into the scalability and robustness of membrane-based evaporative cooling for next-generation high-power electronics.

Prof. Damena Agonafer is an Associate Professor and Inaugural Clark Faculty Fellow in the Department of Mechanical Engineering at the University of Maryland, College Park. In 2025, he received the Presidential Early Career Award for Scientists and Engineers (PECASE), the highest honor bestowed by the United States government on early-career scientists and engineers. Professor Agonafer's research sits at the intersection of thermal fluid sciences, interfacial transport phenomena, and energy systems. His work focuses on developing advanced materials and engineering novel systems for the thermal management of power-dense electronics, as well as for thermochemical and electrochemical energy storage. By tuning solid-liquid-vapor interactions at micro-and nanoscale lengths, his research aims to enable transformative advances in energy and thermal technologies. His group designs micro- and nanostructured materials for phase change heat transfer, interfacial transport, and energy storage applications. These innovations support a range of applications, including high-power electronics cooling, battery thermal management, data center cooling, and more efficient HVAC systems. Professor Agonafer received his PhD from the University of Illinois Urbana-Champaign and completed his postdoctoral training at Stanford University in Professor Ken Goodson's Nanoheat Lab. His honors include the Sloan Research Fellowship, the NSF CAREER Award, the Google Research Award, the Cisco Research Award, and multiple ASME early-career awards. He was also selected to participate in the National Academy of Engineering's Frontiers of Engineering Symposium. He currently serves as a site lead for the NSF Engineering Research Center on Environmental Refrigerant Technology, which is focused on developing a sustainable refrigerant lifecycle to address key challenges in the HVACR industry.

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