A Real Cool Sound

After years of study, thermo-acoustics—using sound as a cooling agent—may finally move out of the research lab and into actual use.

Although not yet commercially viable, test projects have shown that the technology can work. In the recently completed “Triton” project, conducted for the Office of Naval Research, researchers, including those from Penn State University, were able to apply thermo-acoustics to three-ton air conditioners.

The technology, according to chief researcher Prof. Steven L. Garrett, makes use of acoustic drivers that function like loudspeakers to bounce sound around a sealed chamber. Because sound waves are air that is expanding and compressing, regions of air become hot and cold. The temperature differential at various parts inside the cavity can be used for an external cooling system, he explains. Garett has successfully used the technology to create an ice cream freezer.

In the case of project Triton, says Steve McElvany, the project’s program officer, researchers hoped to develop a system that would operate at or above the efficiency of a closed-cycle refrigerator. Unfortunately, he concedes, the project fell short of the goal. However, he believes that the efficiency of thermo-acoustic systems will eventually match conventional systems.

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