Experimental investigation of a standing-wave thermoacoustic electricity generator with different working gases

Thermoacoustic electricity generation is an environmentally friendly alternative technology to generate electrical energy from waste heat or other low-grade heat sources. The standing-wave type offers a simple and compact configuration. We experimentally studied a standing-wave thermoacoustic electricity generator with three working gases: air, nitrogen, and argon. This study evaluates the onset temperature difference, generated sound frequency, pressure amplitude, output electrical power, and optimal load resistance when the mean pressure of the working gases increased from 100 kPa to 500 kPa. A mean pressure of 200 kPa was found to be optimal for all tested working gases, resulting in the smallest onset temperature difference and the highest electrical power output. In general, the smallest onset temperature difference was 233 degrees C, while the largest root mean square electrical power was 1.54 W, both obtained with air as the working gas, with a heating power of 378 W. In addition, sound frequencies generated by all test gases increased by less than 2%, while pressure amplitudes increased nearly threefold. Furthermore, load resistances in the range of 10 Omega\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Omega $$\end{document} to 50 Omega\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Omega $$\end{document} were found to be the optimal load to extract the maximum electrical power.