Cool Air: A Sound ApproachNeil Gross
COMPRESSORS ARE THE UNGAINLY guts of air conditioners, refrigerators, and industrial cooling systems. Because pistons, crankshafts, and other moving parts are essential, compressors guzzle electricity while pumping refrigerants through cooling pipes. But not for long, if MacroSonix Corp. in Richmond, Va., has its way. President Tim S. Lucas has invented an energy-stingy compressor that requires no moving parts. He recently showed a prototype to a meeting of acoustical engineers in San Diego.
The compressor's secret: superpowerful sound waves. Energy transmitted by sound is already used by ultrasonic welding to melt plastics. Beyond a certain amplitude, though, sound energy dissipates as shock waves. Lucas discovered he could thwart this dissipation by precisely shaping the sound waves inside special containers called resonators. These can generate sound waves that pack 1,600 times more energy than ever before and can create pressures reaching 500 pounds per square inch. "It's one of the most exciting things to come along in acoustics in several years," says Gregory W. Swift, an acoustics expert at Los Alamos National Laboratory.