Known as much for its quirky ice cream flavors as for being environmentally aware, Ben & Jerry's has been working on a way to eliminate refrigerants from freezers needed to keep ice cream frozen in scoop shops.

Using Pennsylvania State University as its research partner, Ben & Jerry's, owned by Anglo-Dutch conglomerate Unilever, has announced a working thermoacoustic refrigeration prototype that chills with sound waves. Penn State's compact chiller substitutes sound waves for environment-damaging chemical refrigerants. Hooked up to a standard ice cream sales freezer cabinet in a Ben & Jerry's retail scoop shop, the environmentally friendly unit successfully kept the creamy merchandise in delicious condition, according to Ben & Jerry's.

"We expect this new compact approach to thermoacoustic chillers to be used first in applications that are difficult for chemical refrigeration, such as beverage vending machines, cooling microprocessor chips in computers and, of course, ice cream sales cabinets," said Steven Garrett, leader of the thermoacoustic chiller research team.

The thermoacoustic chiller uses helium gas instead of chemical refrigerants. Helium does not burn, explode or combine with other chemicals. If released into the atmosphere, it drifts harmlessly into outer space. The chiller prototype takes advantage of helium's inertness and high thermal conductivity as well as the fact that a sound wave is a rapid succession of compressions and expansions of the gas that carries it. When a gas is compressed, it heats up. When it expands, it cools down.

"In thermoacoustics, we arrange the compressions and expansions so that all of the heat of compression is deposited at one end of the system, where it can be exhausted into the room," Garrett said. "

We arrange for all of the expansions to occur at a different location where the cooling, due to expansion, can be used to refrigerate ice cream, for example. Our compact unit also makes this happen with no mechanical valves or cams or linkages."

The thermoacoustic chiller is patented by Penn State. Negotiations for a license are in progress with a startup company formed to commercialize the technology.

To view a Flash demonstration of the technology, visit