Thermoacoustic Refrigeration

By Jackie Branscomb

Motivation

• Pros– Uses sound for refrigeration –no harmful

chemicals (CFC’s, HFC’s, HCFC’s)– Few moving parts—more reliable– Not harmful to the environment

• Cons– Most efficent is approaching 40% of Carnot limit– 20-30% overall efficiency

Parts of Acoustic Refrigerator

• Two main parts– Driver

• Houses the Loudspeaker– Resonator

• Houses the gas (in this case Helium)• The hot and cold heat exchangers

• Houses the Stack

How it works• Moving coil Loudspeaker

– Inside 2 magnets with metal coil between them, current is induced causing coil to move

– Creates sound waves up to 200 dB!

• Resonator—where gas cooling and compression take place– Uses inert gas, commonly Helium

• Stack– Series of small parallel channels through which pressure and velocity

of waves change– In between the heat exchangers

• Heat Exchangers– Hot heat exchanger to remove excess heat– Cold heat exchanger for refrigeration

Acoustic Refrigerator

Applications

• Ben & Jerry’s– Ice cream storage containers– 200 L at 18 degrees Fahrenheit

• U.S. Navy– Wants acoustic refrigerators for submarines– Refrigerant leaks on subs are a deadly problem– With acoustic refrigerators, no harmful fluids