What are the outstanding research issues which should be addressed to understand how to improve thermoacoustic refrigerator performance in the future?
The reason that thermoacoustic technology has progressed so rapidly during the past decade is that there has been an excellent theoretical understanding of the thermoacoustic heat pumping process which was developed by N. Rott in the late 1960’s and early 1970’s, and by J. Wheatley and G. Swift in the 1980’s, and G. Swift in the 1990’s. Unfortunately, that understanding has thus far been limited to a fairly small portion of the available “parameter space.” In particular, existing models have been limited to fairly low acoustic Mach Numbers (Mac < 3% or p1/pm < 5%), due to the one-dimensional nature of the equations, the limitations of linear acoustics, the absence of mean flow, and the assumption of a stable laminar boundary layer. Since the power density of thermoacoustic devices depends upon (p1/pm)^2, there is quite a strong motivation to understand thermoacoustics at higher amplitudes. Progress in this direction will require the construction of thermoacoustic refrigerators which ca
