Experimental investigation of a thermo-acoustic prime mover with helium–argon mixtures as working gases

In order to further investigate the effect of the working gas (especially, the helium–argon mixture) on the actual operating characteristics (including static and dynamic characteristics) of a thermo-acoustic engine, an experimental standing-wave thermo-acoustic engine was built up in this study. The thermo-acoustic system was introduced in detail, and experimental results on the thermodynamic characteristics of the system with helium–argon mixtures, especially the dynamic and oscillating characteristics, were also presented. At different molar fractions in the helium–argon mixture, under different charging pressures, the pressure ratio and the pressure amplitude of the thermo-acoustic system gradually increase with heating temperature. Under given conditions of the charging pressure and heating temperature, there exists an optimal molar fraction in the helium–argon mixture. It is obvious that using a certain proportion of helium–argon mixture as the working gas, the on-set temperature of the thermo-acoustic system can be effectively reduced and this is helpful in using low-quality energy and enhancing the thermodynamic efficiency of the whole system. Using helium–argon mixtures can widen the application range of the thermo-acoustic system and obtain any frequency between the resonance frequencies of two pure substances. However, the unexpected large fluctuation of the resonance frequency will make the engineering application of the system difficult. These results will provide a reliable experimental basis for further improving the thermodynamic performance of the thermo-acoustic system and broaden the application range.