The boiling of water is at the heart of many industrial processes, from the operation of electric power plants to chemical processing and desalination. But the details of what happens on a hot surface as water boils have been poorly understood, so unexpected hotspots can sometimes melt expensive equipment and disable plants.

Now researchers at MIT have developed an understanding of what causes this extreme heating — which occurs when a value known as the critical heat flux (CHF) is exceeded — and how to prevent it. The new insights could make it possible to operate power plants at higher temperatures and thus significantly higher overall efficiency, they say.

The findings are reported this week in the journal Nature Communications, in a paper co-authored by mechanical engineering postdoc Navdeep Singh Dhillon, professor of nuclear science and engineering Jacopo Buongiorno, and associate professor of mechanical engineering Kripa Varanasi.

“Roughly 85 percent of the worldwide installed base of electricity relies on steam power generators, and in the U.S. it’s 90 percent,” Varanasi says. “If you’re able to improve the boiling process that produces this steam, you can improve the overall power plant efficiency.”

The bubbles of vapor that characterize boiling, familiar to anyone who has ever boiled water on a stove, turn out to limit energy efficiency. That’s because gas — whether it’s air or water vapor — is highly insulating, whereas water is a good absorber of heat. So on a hot surface, the more area that is covered with bubbles, the less efficient the transfer of heat energy becomes.

If those bubbles persist too long at a given spot, it can significantly increase the temperature of the metal underneath, since heat is not transferred away fast enough, Varanasi says — and can potentially melt part of the metal.

“This will most certainly damage an industrial boiler, a potentially catastrophic scenario for a nuclear power plant or a chemical processing unit,” says Dhillon. When a layer of bubbles limits heat transfer, “locally, the temperature can increase by several thousand degrees” — a phenomenon known as a “boiling crisis.”