Working gases in thermoacoustic engines

Abstract

The best working gases for thermoacoustic refrigeration have high ratios of specific heats and low Prandtl numbers. These properties can be optimized by the use of a mixture of light and heavy noble gases. In this paper it is shown that light noble gas-heavy polyatomic gas mixtures can result in useful working gases. In addition, it is demonstrated that the onset temperature of a heat driven prime mover can be minimized with a gas with large Prandtl number and small ratio of specific heats. The gas properties must be optimized for the particular application of thermoacoustics; it cannot be assumed that high specific heat ratio and low Prandtl number are always desirable.

Experimental study on the heat transfer at the heat exchanger of the thermoacoustic refrigerating system

“…Energy flux density around the heat exchangers was visualized and implications on the heat exchanger design were examined. Belcher et al [11] studied working gases suitable for use in thermoacoustic systems.…”

A two-stage traveling-wave thermoacoustic electric generator with loudspeakers as alternators

“…and the larger ratio of specific heats 1.67 γ = , which are useful to improve the thermoacoustic engine efficiency [24,25]. Thus, this thermoacoustic system uses helium as the working gas.…”

System Identification and Resonant Control of Thermoacoustic Engines for Robust Solar Power

“…To such a situation, suppressing mean-flow buckling but keeping thermoacoustic instability is a remedy. The control of mean-flow buckling was usually through passive approaches, such as re-shaping the chambers [11][12][13][14], changing the working gas [15], re-designing the heat regeneration [16][17][18][19][20][21][22], etc., based on the analysis of computation fluid dynamics as in [11,23,24] for example. As indicated in the literature of combustion instabilities [25][26][27][28], suppression of mean-flow buckling is usually accompanied by reduction of acoustic motions.…”