Researchers at the Hong Kong University of Science and Technology (HKUST) have made significant strides in eco-friendly cooling technology by developing a sustainable method to manipulate interfacial heat transfer. This breakthrough has the potential to improve cooling performance in various applications, including electronics, buildings, and solar panels.
As global temperatures rise, the need for efficient and sustainable cooling solutions has become more pressing. Traditional active cooling methods, which rely heavily on energy consumption, are being scrutinized for their environmental impact. In contrast, passive cooling methods, which use natural processes to reduce heat without energy consumption, have gained significant interest for their eco-friendly nature.
One promising area in passive cooling research is the use of metal-organic frameworks (MOFs). MOFs are porous materials capable of capturing water vapor from the air, which can enhance energy efficiency in cooling systems. However, a major drawback of MOFs is their low thermal conductivity, which hampers their effectiveness as thermal conductors. The presence of water molecules in MOFs further reduces their thermal conductivity, posing a challenge for their use in cooling applications.
To overcome this limitation, researchers have focused on improving the interfacial thermal conductance (ITC) between MOFs and the materials they contact. Traditional methods such as using adhesion layers, nanostructures, and chemical modifications have shown some success but are limited by the complexity of precise atomic control required for these techniques.
The research team led by Prof. ZHOU Yanguang at HKUST introduced an innovative strategy that utilizes a water adsorption process to enhance ITC between MOFs and their contacting substrates. Using frequency-domain thermoreflectance (FDTR) measurements and molecular dynamics (MD) simulations, the team achieved a substantial increase in ITC—from 5.3 MW/m²K to 37.5 MW/m²K, a remarkable 7.1-fold improvement.
This enhancement is attributed to the formation of dense water channels within the MOFs. These channels create additional pathways for thermal energy transfer, significantly boosting interfacial heat dissipation. Further analysis revealed that the adsorbed water molecules activate high-frequency vibrations and increase the overlap of vibrational density of states between the substrate and MOFs, enhancing thermal energy transfer.
“This innovative study not only provides new insights into thermal transport across MOFs and other materials but also holds great promise for enhancing the performance of cooling applications involving MOFs. By leveraging 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.
The findings of this study represent a major advancement in the field of passive cooling and could lead to more effective and sustainable cooling solutions in various applications. By improving the thermal conductivity of MOFs through interfacial enhancements, researchers have opened new possibilities for eco-friendly cooling technologies that reduce energy consumption and environmental impact.
Source
Direct observation of tunable thermal conductance at solid/porous crystalline solid interfaces induced by water adsorbates, Nature, 2024-03-14
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