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Researchers are developing a sustainable strategy to manipulate interfacial heat transfer for environmentally friendly cooling applications

HKUST researchers improve the performance of environmentally friendly cooling applications by developing a sustainable strategy to manipulate heat transfer at the interface

Heat transferred from the solid substrate to passively cooling porous crystals via water-filled interfaces. Credit: HKUST

Researchers from the School of Engineering at Hong Kong University of Science and Technology (HKUST) have developed a sustainable and controllable strategy to manipulate interfacial heat transfer, paving the way to improve the performance of eco-friendly cooling in various applications such as electronics , buildings and solar panels.

The team’s research work, titled “Direct Observation of Tunable Thermal Conductance at Solid/Porous Cystalline Solid Interfaces Induced by Water Adsorbates,” was recently published in Nature communication. Led by Prof. Zhou, the team included his Ph.D. students Wang Guang, Fan Hongzhao and Li Jiawang, as well as Associate Head of the Department of Mechanical and Aerospace Engineering at HKUST Prof. Li Zhigang.

As the demand for effective cooling solutions continues to grow due to rising global temperatures, scientists around the world have been actively researching energy-saving cooling technologies that are more effective. Compared to active cooling, which is completely dependent on energy consumption, passive cooling relies on natural processes and design principles to reduce heat and maintain a comfortable temperature with low or no energy consumption. This approach has therefore generated widespread interest among researchers due to its environmentally friendly nature and zero-electricity feature.

An emerging area of ​​research is passive cooling using metal-organic frameworks (MOFs), which are porous materials that can capture water vapor from the air and can be used to increase energy efficiency in room temperature space cooling applications.

However, MOFs typically exhibit low thermal conductivity, making them poor thermal conductors. Moreover, the presence of adsorbed water molecules in MOFs further reduces their effective thermal conductivity. This limitation leaves little room for manipulating the intrinsic thermal transport properties of MOFs to improve their cooling performance.

HKUST researchers improve the performance of environmentally friendly cooling applications by developing a sustainable strategy to manipulate heat transfer at the interface

Prof. Zhou Yanguang (second from right), Assistant Professor of Mechanical and Aerospace Engineering at HKUST, and his Ph.D. students Fan Hongzhao (first left), Wang Guang (second left) and Li Jiawang (first right). Credit: HKUST

To address this problem, researchers around the world have turned their attention to heat dissipation at the interface between MOFs and the materials they come into contact with. Various approaches, including the use of adhesion layers, nanostructures, chemical modification, and self-assembling monolayers, have been employed to improve interfacial thermal conductivity (ITC). However, synthesizing or fabricating buffer layers with precise atomic control is a challenging task, limiting the potential applications of these methods.

In their groundbreaking work, the research team led by Prof. Zhou Yanguang from HKUST’s Department of Mechanical and Aerospace Engineering introduced a sustainable and controllable strategy to manipulate interfacial heat transfer between the contacted substrate and typical MOFs by using a water adsorption process.

Through extensive frequency domain thermoreflectance (FDTR) measurements and molecular dynamics (MD) simulations, they demonstrated a remarkable improvement in ITC between the contacted substrate and MOFs. The ITC was increased from 5.3 MW/m2K up to 37.5 MW/m2K, which represents an improvement of about 7.1 times. Effective improvements are also observed in other Au/MOF systems.

The research team attributes this improvement to the formation of dense water channels, made possible by the adsorbed water molecules in MOFs. These channels serve as additional thermal pathways, significantly improving the transfer of thermal energy across the interfaces.

Further analysis using the direct decomposition method in the frequency domain developed by the team found that the adsorbed water not only activates the high-frequency vibrations, but also increases the overlap of the vibrational density of states between the substrate and the MOF, thereby improving the thermal energy dissipation of the substrate to MOF, highlighting the bridging effect of the adsorbed water molecules.

“This innovative study not only provides new insights into thermal transport between MOFs and other materials, but also holds promise for improving the performance of cooling applications involving MOFs. By utilizing the water adsorption process, our team has achieved a breakthrough in manipulating interfacial heat transfer, paving the way for more efficient cooling technologies,” said Prof. Zhou.

More information:
Guang Wang et al., Direct observation of tunable thermal conduction at interfaces between solid and porous crystalline solids induced by water adsorbates, Nature communication (2024). DOI: 10.1038/s41467-024-46473-8

Provided by the Hong Kong University of Science and Technology

Quote: Researchers develop a sustainable strategy to manipulate interfacial heat transfer for eco-friendly cooling applications (2024, May 28) retrieved on May 28, 2024 from https://techxplore.com/news/2024-05-sustainable-strategy-interfacial-eco-friendly.html

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