New Two-Phase Acoustic Chillers For Controlled Personal Cooling (1000-555)

Novel concepts in thermoacoustic refrigeration are considered for use in a cooling garment for civilian or military first responders. Thermoacoustic refrigerators are of interest as alternatives to conventional vapor compression devices, since they can be very compact, using a minimum of simple, inexpensive parts, and offer features such as variable cooling capacity (allowing proportional control) and ready scalability to smaller sizes in ways that conventional vapor compression refrigerators are not capable. Backpack-sized devices exist now, and our team will investigate the minimum size that can meet the cooling requirement. The coefficient of performance (COP) of small thermoacoustic refrigerators is normally about 20% of the ideal (Carnot cycle) COP, which is actually better than similarly scaled vapor compression coolers which currently rate at about 10%. We propose a method to further enhance the efficiency of thermoacoustic chillers by eliminating one of the subsystem components that usually cause performance losses. The heat exchanger that is normally used at the end of the thermoacoustic "stack" will be removed by designing the system with a condensing working fluid that bears the thermal load more efficiently.