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Considering from the second law of thermodynamics, the equation for entropy generation rate near a single-plate, representative of the stack inside thermoacoustic refrigerators was derived in this paper. It indicates that entropy generation is produced due to heat transfer in the x-y direction of finite temperature gradients and fluid friction irreversibility. Analysis of global entropy generation rate versus the position of the stack, 2x/λ and the volume porosity, ϕ were carried out. The results demonstrated that the optimal position of the stack was within 0.8 <2x/λ <0.83, and the optimal volume porosity was 0.7. [ABSTRACT FROM AUTHOR]

Based on linear thermoacoustic theory, an open-air traveling-wave thermoacoustic generator with 1 bar air has been designed and built up. The dimensions of regenerator and resonator influence on the resonant frequency, driver ratio, acoustic power and temperature difference are simulated and optimized to acquire the perfect performance, respectively. According to above simulated results, the acoustic pressures at the open end and 0.5 m far away from the open end of the resonator versus the heating power are investigated experimentally. The improved maximum acoustic pressures are up to 133 dB and 101 dB ref 20 μPa, respectively. [ABSTRACT FROM AUTHOR]