Researchers at Massachusetts Institute of Technology, Cambridge, say they found a way to improve the efficiency of steam condensation-the key to worldwide production of electricity and clean water. It has been known for years that making steam-condenser surfaces hydrophobic could improve the efficiency of condensation by causing the water to quickly form droplets. But most hydrophobic materials have limited durability, especially in steamy industrial settings. The new approach to coating condenser surfaces should overcome that problem, according to researchers.
The covalent-bonding process the team developed is significantly more stable than previous coatings, even under harsh conditions. Tests of metal surfaces coated using the team’s process show “a stark difference,” says Kripa Varanasi, professor of mechanical engineering. In tests, the material stood up well even when exposed to steam at 100°C in an accelerated endurance test. The coating can easily be applied to conventional condenser materials-typically titanium, steel, copper, or aluminum-in existing facilities, using a process called initiated chemical vapor deposition (iCVD). For more information: Kripa Varanasi, 617/324-5608, [email protected], http://varanasi.mit.edu.
Image caption – On typical hydrophobic coatings, droplets forming from high-temperature steam soon spread out to coat the surface, quickly degrading their performance. The coating seen here maintains its ability to foster droplet formation over long periods.
