"And the stars are projectors, yeah, projecting our lives down to this planet Earth." - Modest Mouse
Ice cream moguls Ben & Jerry's have funded Penn State acousticians to develope an eco-friendly refrigerator which uses sound waves instead of CFC refrigerants.
.The Penn State thermoacoustic chiller uses helium gas instead of chemical refrigerants. Helium, which is used to keep birthday party balloons aloft, doesn't burn, explode or combine with other chemicals. If released into the atmosphere, helium drifts harmlessly into outer space.
The Penn State chiller 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, its heats up. When it expands, it cools down," Garrett explains. "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. 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."
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