A new technology has been developed that enhances heat transfer performance by up to 5.5 times by improving the way water droplets form and fall. This advancement is expected to increase energy efficiency in power plants and desalination facilities, as well as improve cooling performance in electronic devices.
The Korea Advanced Institute of Science and Technology (KAIST) announced on August 23 that a joint research team led by Professors Nam Young-seok from the Department of Mechanical Engineering and Lim Sung-kap from the Department of Bio and Chemical Engineering has developed a method to enhance the heat transfer efficiency of the condensation process by adjusting the thickness and structure of polymer coating films.
Condensation refers to the process of water vapor turning into liquid water. It is utilized in various applications, including converting steam back into water in power plants, obtaining fresh water from seawater through desalination, and cooling electronic devices. The efficiency of heat transfer during condensation is largely determined by how quickly the water that forms on the surface is removed.
Previous technologies faced limitations: roughening the surface to increase droplet formation hindered droplet removal, while smoothing the surface reduced droplet generation.
The research team addressed this issue by utilizing nano-sized aggregates, previously considered defects in conventional polymer films. They employed a method called initiator-assisted chemical vapor deposition (iCVD) to create thin polymer films that allowed for the formation of these nano-sized aggregates. iCVD is a technique that deposits gaseous raw materials onto a surface to create thin polymer films, offering the advantage of uniform coating on complex surface shapes.
The nano-sized aggregates formed in this process acted as 'seed sites' for droplet formation. As a result, the thin polymer films produced approximately three times more droplets than thicker films.
Additionally, the research team applied heat treatment to reduce the adhesion forces on the surface. By adjusting the thickness of the polymer film, they increased droplet generation while also enhancing the rate at which droplets were removed.
When the polymer film was applied to copper tubes used in actual condensers, it achieved heat transfer performance that was up to about 5.5 times higher than that of standard copper surfaces and over 50% higher than that of existing hydrophobic coated surfaces.
Professor Nam stated, "The significance lies in utilizing what was previously considered a defect in nano structures as a factor that aids droplet generation. We expect this technology to be applicable in various energy and environmental fields, including industrial heat exchangers, due to its ability to provide thin and uniform coatings on complex surfaces."
* This article has been translated by AI.
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