About

Damena Agonafer is an Associate Professor and Clark Faculty Fellow in the Department of Mechanical Engineering at the University of Maryland. His research interests lie at the intersection of thermal-fluid sciences, interfacial transport phenomena, and renewable energy. He focuses on developing novel materials and systems for thermal management of power and microelectronic systems, as well as for thermochemical and electrochemical energy storage applications. His goal is to achieve transformational changes in technologies by tuning and controlling solid-liquid-vapor interactions at micro- and nano-length scales. Specific areas of focus include the development of micro- and nanostructures for phase change heat transfer, thermochemical energy storage, and interfacial transport phenomena, with applications in cooling high-powered electronics, battery thermal management, data center cooling, and improving HVAC system efficiency.

Research topics

• Mechanical engineering
• Materials science
• Nanotechnology
• Mechanics
• Engineering
• Thermodynamics
• Composite material
• Physics

Selected publications

• Direct-to-Chip Evaporative Cooling: Effect of Liquid Delivery Layer onFlow Maldistribution and Thermal Performance

  SSRN Electronic Journal · 2026-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Extremely Low Thermal Resistance Architectures for AlxGaN1-x Semiconductor Devices

  Open MIND · 2026-02-21

  preprint

  Next-generation high-power radio-frequency (RF) devices increasingly demand transistors that operate efficiently with high gain at high frequencies. High-aluminum-content ultra-wide-bandgap (UWBG) AlGaN alloys have shown great potential for enabling such high-frequency RF technologies. However, the widespread adoption of AlGaN-based RF devices is limited by thermal-management challenges arising from the intrinsically low thermal conductivity of AlGaN, which leads to higher device thermal resistance for a given geometry compared to GaN RF devices. As a result, these next-generation devices are highly susceptible to self-heating. This study investigates the thermal behavior of UWBG AlGaN devices, focusing on the effects of AlGaN channel thickness, substrate technology, and high-k material integration on reducing device thermal resistance to enable high-power operation. Experimental results demonstrate a record-low thermal resistance of 3.96 mm$\cdot$K/W when an AlN substrate is employed and the AlGaN channel thickness is reduced to 5 nm. These findings provide valuable insights into mitigating thermal limitations in UWBG devices through device-level engineering and the strategic integration of high-k materials.

  DOI

• Augmenting the Heat Capacity of Dielectric Liquids using Encapsulated Phase ChangeMaterials

  SSRN Electronic Journal · 2026-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Extremely Low Thermal Resistance Architectures for AlxGaN1-x Semiconductor Devices

  arXiv (Cornell University) · 2026-02-21

  articleOpen access

  Next-generation high-power radio-frequency (RF) devices increasingly demand transistors that operate efficiently with high gain at high frequencies. High-aluminum-content ultra-wide-bandgap (UWBG) AlGaN alloys have shown great potential for enabling such high-frequency RF technologies. However, the widespread adoption of AlGaN-based RF devices is limited by thermal-management challenges arising from the intrinsically low thermal conductivity of AlGaN, which leads to higher device thermal resistance for a given geometry compared to GaN RF devices. As a result, these next-generation devices are highly susceptible to self-heating. This study investigates the thermal behavior of UWBG AlGaN devices, focusing on the effects of AlGaN channel thickness, substrate technology, and high-k material integration on reducing device thermal resistance to enable high-power operation. Experimental results demonstrate a record-low thermal resistance of 3.96 mm$\cdot$K/W when an AlN substrate is employed and the AlGaN channel thickness is reduced to 5 nm. These findings provide valuable insights into mitigating thermal limitations in UWBG devices through device-level engineering and the strategic integration of high-k materials.

  PublisherOA PDF

• Experimental investigation of Direct-to-Chip Evaporative Cooling using HollowMicropillar Arrays for High-Power AI Accelerators

  SSRN Electronic Journal · 2026-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Hierarchical hollow silica shells for scalable and passive superinsulation

  Materials Today · 2025-12-25 · 1 citations

  articleOpen access

  Porous silica materials are highly valued for their thermal management potential, with their high porosity and large surface area making them ideal for insulation. However, challenges persist in their practical manufacturing and in establishing clear relationships between their structure and insulation performance. Here, we report a rapid 10-minute gelation process under ambient temperature and pressure conditions to enable scalable manufacturing of tunable SiO 2 hollow spheres. By systematically investigating the effects of synthetic conditions, the resulting SiO 2 hollow spheres demonstrate a thermal conductivity as low as 15 mW m −1 K −1 and porosity exceeding 98 %. We found through simulations that a higher contact area between hollow silica particles leads to increased thermal conductivity. Additionally, we incorporated hollow silica into ceramic fibers, which presents additional advantages for thermal protection against transient high-temperature loads by effectively delaying heat propagation through heat absorption and self-extinguishing behavior in the presence of fire. Notably, the production process features a carbon footprint of 17.07 kg CO 2 /kg and a production yield of up to 40 %, striking a balance between performance and sustainability. This study marks a key step in advancing SiO 2 hollow spheres as effective thermal management materials.

  PublisherDOI

• Dynamic Thermal Management of a MOSFET Power Module Using a Novel Three-Component Phase Change Material

  ASME Journal of Heat and Mass Transfer · 2025-07-04 · 3 citations

  articleSenior author

  Abstract Silicon carbide (SiC) devices are increasingly favored in modern power modules, enabling significant size reductions while supporting higher power densities, resulting in heat fluxes exceeding 400 W/cm2. However, the time-varying loads typical in many applications induce substantial temperature cycling, posing thermo-mechanical challenges that necessitate cooling systems capable of handling peak loads. This study introduces a novel hybrid thermal management approach employing a three-component composite phase change material (PCM) integrated with standard liquid cooling to mitigate temperature cycling, lower peak junction temperatures, and extend the lifespan of power modules. The proposed PCM composition combines Field's metal (FM) with micro-encapsulated organic PCM (MEP) embedded within a graded porous honeycomb structure in the copper baseplate of the module. Transient thermal modeling is done under various time-varying loads and electric vehicle drive cycles, examining the effects of different times and duty factors. Results show a maximum temperature cycling reduction of 13.3% and 13.9% at heat transfer coefficients of 3000 W/m2 K and 4000 W/m2 K, respectively, compared to a power module with no PCM. Correspondingly, a power module lifecycle improvement of 120.1% and 112.5% is observed under these conditions. Thicker PCM-integrated baseplates improved transient performance due to higher thermal capacitance despite greater resistance. Additionally, FM-dominated PCM, with higher volumetric energy density, outperformed MEP-dominated PCM. These findings underscore the potential of a three-component composite PCM in power modules for superior transient thermal management and enhanced module durability.

  PublisherDOI

• Design and modeling of hollow micropillars evaporator for thermal management in high heat flux applications: Numerical analysis

  Applied Thermal Engineering · 2024-12-10 · 8 citations

  articleOpen accessSenior authorCorresponding
  PublisherOA PDFDOI

• An Experimental Investigation of Sintered Particle Effect on Heat Transfer Performance in an “Annular Flow” Evaporation Tube

  Journal of Thermal Science and Engineering Applications · 2024-04-03 · 1 citations

  articleOpen access

  Abstract Wicking structures have been widely used within passive heat transfer devices with high heat fluxes, such as heat pipes, to enhance their thermal performance. While wicking structures promote capillary pumping of the working fluid and thin film evaporation, they can result in capillary evaporation and further enhance the evaporation heat transfer. In this study, a 0.5 mm thick layer of 105 µm sintered copper particles was added to the inner wall of a copper tube, aiming to form an “annular flow” and enhance the heat transfer characteristics by taking advantage of thin film and capillary evaporation. Acetone was chosen as the working fluid, and the performance of an evaporation tube was tested for power inputs of 10, 30, 50, and 70 W. For each power input, trials were run at inclination angles varying from −90 deg to 90 deg to investigate the capillary effects. The temperature measurements showed that the temperature distribution along the evaporation tube is always downward sloping, meaning the temperature at the fluid inlet is larger than the outlet. Results show that an “annular flow” formed by a thin layer of sintered particles can promote thin film and capillary evaporation and, therefore, boost the evaporation heat transfer coefficient.

  PublisherOA PDFDOI

• Microscale Evaporation for High Heat Flux Applications

  WSPC series in advanced integration and packaging · 2024-02-01

  book-chapter1st authorCorresponding
  PublisherDOI

Recent grants

• CAREER: Fundamental Transport Mechanisms of Evaporation From Non-Axisymmetric Droplets Confined on Hollow Micropillars Structures

  NSF · $395k · 2020–2023

Frequent coauthors

• Yoonjin Won

  University of California, Irvine

  13 shared

• Binjian Ma

  Harbin Institute of Technology

  12 shared

• Kenneth E. Goodson

  12 shared

• Baris Dogruoz

  10 shared

• Mehdi Asheghi

  10 shared

• Shan Li

  8 shared

• Hyoungsoon Lee

  Chung-Ang University

  8 shared

• Mark A. Shannon

  7 shared

Awards & honors

• Alfred P. Sloan fellowship
• Graduate Engineering Minority Fellowship
• NSF Center of Advanced Materials for Purification of Water w…
• Google Research Award
• Sloan Research Fellowship Award