Coating Boasts a Power Plant Boost

TUESDAY, DECEMBER 2, 2014


A new nano-engineered coating for power plants has the potential to save millions of dollars in fuel and avert thousands of tons of carbon dioxide emissions, its developers at MIT say.

Two thousand times thinner than a sheet of paper, the coating causes water droplets to bead up and roll off, self-shedding the blanket of steam that normally envelopes (and slows down) condensers.

The coating is so thin that it doesn't block condensation, but is strong enough to survive years of steam exposure, according to MIT.

For years, researchers have searched for a way to make steam-condenser surfaces hydrophobic, but most materials have limited durability and would start to degrade within minutes of exposure to the hot steam.

The team says the new technology can save 0.58 gigatons of carbon dioxide emissions—more than solar or wind power—through improved efficiency.

Developing DropWise

The research has snowballed into a startup called DropWise, which is developing a "grafted" hydrophobic coating that prevents water from building up on pipes when applied to condenser surfaces in power plants.

The new coating is currently in the development stage, and the company is working on scaling up the process to apply the coating at a large scale.

The startup was created by Kripa Varanasi, associate professor in MIT's Department of Mechanical Engineering (MechE); Karen Gleason, professor and associate provost in the Department of Chemical Engineering (ChemE); MechE postdoc Adam Paxson; and ChemE postdoc David Borelli.

Novel Application Method

A condenser has cold water flowing inside its tubes so that hot steam outside the tubes can condense, which creates a powerful suction force to spin the turbine. However, the metals used on the condenser tubes attract water, so the steam forms a thick blanket that insulates the surface and slows down the process.

By adding a hydrophobic coating, the water rolls off and steam condenses faster, generating power more efficiently so less fuel is burned.

The MIT team's new development of a covalent-bonding process is significantly more stable than previous coatings, Varanasi said when the findings were first reported.

Paxson explains how the coating and application method work in this DropWise introduction video.

The new coating can be applied to condenser materials using a process called initiated chemical vapor deposition (iCVD), which was developed by the Gleason Lab at MIT. The technique is a single-step, low-energy vapor-phase method that allows extremely thin coatings to be deposited and consumes a very small amount of raw materials.

"Because it's vapor-based, instead of flow- or spray-based, we don't need to fit spray nozzles or other equipment inside a heat exchanger or other complicated geometry. We're essentially 'condensing' the coating onto the surface," Paxson explained in an email.

A paper on the research, "Stable Dropwise Condensation for Enhancing Heat Transfer via the Initiated Chemical Vapor Deposition (iCVD) of Grafted Polymer Films," was previously published in Advanced Materials.

Seeking Partnerships

DropWise is now looking to partner with coatings and service providers to commercialize the coating.

The company was recently named a Gold Winner at the MassChallenge 2014 Accelerator Program, which came with a $50,000 prize.

MassChallenge is the world's largest startup accelerator, according to MIT. The program has helped develop another one of Varanasi's coatings startups, LiquiGlide, which is developing nonstick, nontoxic coatings that help condiments slide out of their bottles.

 

   

Tagged categories: Coating chemistry; Coating Materials; Colleges and Universities; Developers; Nanotechnology; North America; Power Plants; Research; Water repellents

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