Fundamental study for heat pump stack length determination with complex flow paths in a compact thermoacoustic system

The miniaturization of thermoacoustic systems is expected to find practical applications in various fields. To achieve miniaturization, we focused on the relation of the sound wave in the tube and the length of the heat-pump stack. Accordingly, three types of metal meshes with different channel diameters were prepared, and thermoacoustic systems were designed considering omega tau, a dimensionless quantity. In the experiment, the stack length was varied and the stack temperature difference and heat flow were measured. Consequently, temperature difference and heat flow with respect to the stack length were studied. In addition, even when the stack was short, temperature difference at both ends of the stack was formed. The better stack length in terms of energy efficiency was also examined. Accordingly, we confirmed that the ratio of stack length to wavelength is in the range of 0.2%-0.6%. (c) 2023 The Japan Society of Applied Physics