Inside a Dewey

Jim Beckman’s favorite new word is “dewvaporation.” The word is a combination of “evaporation” and “dew formation.”

Beckman is not a linguist. He is an ASU professor of chemical and materials engineering. The new word is important. Dewvaporation describes the process taking place inside a NEWT Double Helix Tower, an inexpensive device created by Beckman to efficiently make freshwater out of saltwater. The device is affectionately known as “Dewey.”

Dewvaporation describes how Dewey works. Each of the device’s modules contains a heat transfer wall made of plastic. The wall divides the module into two compartments, one for evaporation and one for dew formation.

An external pump sends dirty, salty water down into the evaporation compartment, where an external blower provides an upward stream of air. Heat coming through the heat transfer wall causes most of the water to evaporate into the air. The rest of the water, now with a much higher concentration of salt, exits out the bottom of the module.

At the top of the module, the now humid air mixes with a stream of steam and flows into the dew formation compartment. Heat flows through the heat transfer wall into the evaporation compartment, cooling the air and allowing pure liquid water—dew—to form.

The clean, pure water flows out of the bottom of the device, and the air cycles through the module again.

A standard Dewey is 2 foot by 2 foot by 5 foot in size. A single Dewey contains 20 to 30 modules that can process up to 100 gallons of water per day.—Linley Erin Hall