Scientists turn tiny “defects” into a 5.5x heat transfer boost

Scientists have created a surface coating that can boost condensation heat transfer performance by up to 5.5 times compared to traditional copper surfaces. This innovation, developed by a team from KAIST led by Professor Youngsuk Nam and Professor Sung Gap Im, hinges on carefully controlling the thickness and structure of a thin polymer coating.

This coating fosters more droplet formation during condensation and makes it easier for those droplets to detach, a combination that could significantly improve energy efficiency in power plants, desalination facilities, and the cooling of electronic devices. The key lies in harnessing nanoscale polymer aggregates that were previously considered defects in polymer coatings.

By using initiated chemical vapor deposition (iCVD), the researchers produced an ultrathin polymer layer. This layer encouraged more droplets to form while also improving their detachment. The researchers achieved this by reducing the polymer film thickness, which increased the number of sites where droplets could form, and applying thermal treatment to weaken the force holding droplets to the surface, allowing for easier detachment.

This dual approach effectively overcame the trade-off between droplet formation and removal. The enhanced heat transfer performance of up to 5.5 times that of conventional copper surfaces was demonstrated by applying the coating to copper tubes used in condensers. This new method of using previously regarded as defects as features to help droplets form represents a new strategy for designing condensation surfaces with wide-ranging potential applications in energy, water, and electronics.