Water-shedding coating boosts copper tube heat transfer 5.5x
Researchers have developed an ultrathin polymer coating that significantly enhances condensation heat transfer on copper tubes, potentially improving energy efficiency in power plants and electronics cooling.
A joint research team from KAIST has developed a novel technology that enhances condensation heat transfer by up to 5.5 times compared to conventional copper surfaces. The innovation involves an ultrathin polymer coating applied to surfaces, designed to promote the rapid formation and detachment of water droplets as water vapor condenses into liquid.
Condensation is a crucial process in various industrial applications, including power generation, desalination, and electronic cooling. Efficiently removing condensed water from a surface is key to maximizing heat transfer. However, traditional metal surfaces can develop water films that act as thermal resistance, hindering heat flow. Existing methods to improve condensation, such as roughening surfaces, often trap droplets, while smoothing surfaces can reduce droplet formation sites.
The KAIST team overcame this challenge by utilizing nanoscale polymer aggregates, previously considered surface defects. Using initiated chemical vapor deposition (iCVD), they created ultrathin polymer films. When the film was made thinner, these aggregates formed densely, acting as nucleation sites that encouraged the formation of approximately three times more water droplets than on thicker films.
Further enhancing the process, a heat treatment step was introduced to reduce the adhesion force between the droplets and the surface. This allowed the newly formed droplets to detach more easily before they grew large. By controlling film thickness for droplet nucleation and thermal treatment for droplet removal independently, the researchers created a system where the surface is continuously renewed by fast-forming and detaching droplets, thereby increasing heat transfer efficiency.
When applied to copper tubes commonly used in condensers, the coated surfaces achieved a maximum condensation heat transfer coefficient of approximately 88 kW·m⁻²·K⁻¹. This performance was over 50% better than conventional hydrophobic coatings and significantly higher than untreated copper surfaces. The researchers highlight that their strategy actively uses previously discarded surface 'defects' to improve performance.
This development addresses a fundamental trade-off in condensation heat transfer by leveraging nanoscale surface features, previously seen as defects. By controlling droplet nucleation and mobility separately, the technology significantly boosts heat transfer efficiency. This could have broad implications for industrial heat exchangers, power plants, desalination, and advanced cooling solutions for electronics, aligning with the broader push for more efficient thermal management in energy-intensive applications.
Edited by the news editor with AI from the original report — please refer to the original source.