sound waves used to produce sub freezing temperatures

dasa · December 11, 2002

Sound Waves May

Replace Refrigerants

By Katrina Woznicki

UPI Science News

12-4-2

CANCUN, Mexico (UPI) -- Scientists said Wednesday they have developed technology that converts sound waves into refrigeration, which could lead to more environmentally efficient household and industrial products.

The research team, led by Steven Garrett, professor of acoustics at Pennsylvania State University in College Park, said the thermoacoustics process could be a viable alternative to chemical refrigerants.

Thermoacoustics can work both ways, by removing heat or adding heat. Scientists used tweaked loudspeakers to create high amplitude sound waves in the air.

The amplitude levels were far higher than those at rock concerts, where the decibel level is around 120. At 165 decibels, the sound level is so intense the friction could set fire to hair as gas undergoes such huge acoustic undulations.

The study was funded by ice cream maker Ben & Jerry's and Unilever, its parent company, and presented Wednesday at the First Pan-American/Iberian Meeting on Acoustics in Cancun.

The U.S. Department of Energy and the Navy have tested the potential of thermoacoustics.

The thermoacoustic system managed to bring cooling temperatures down to 8 degrees below zero, well below the freezing point.

"The thermoacoustic refrigeration machine we are developing for Ben & Jerry's (ice cream) would be just about what you would want for use in a home food refrigerator/freezer," Garrett said.

Ganesh Raman, an associate professor in the mechanical, materials and aerospace engineering department at Illinois Institute of Technology in Chicago, and editor of the International Journal of Aeroacoustics, called the research "revolutionary."

"The possibilities, I think, will go well beyond refrigeration," Raman told UPI. "This is an exciting development that only comes once in a while. And unlike other developments, this isn't an incremental step. This is a major leap."

This new step in sound wave technology is equivalent to the strides made in harnessing light waves into laser technology, he explained.