Estimation of the effect of thin-plated surface on a three-staged looped thermoacoustic engine for low-grade heat recovery

This paper introduces two novel structures of looped thermoacoustic engines designed for outdoor low-frequency sound sources. The system consists of three thermoacoustic engines in a loop and a stub for sound radiating, which is characterized by reliability, high efficiency, and compactness. Two thin plates are used to prevent the Gedeon flow, facilitate sound propagation, and adjust the acoustic field. The system with a straight stub achieved a maximum Sound Pressure Level of 126.09 dB at 1 m away, surpassing highest reported records by 25.96 %. The system also achieves a high output efficiency of 3.86 %. The system with tapered stub and a 0.1 mm silicone plate, achieved an SPL of 120.76 dB at 1 m. To maintain the predetermined acoustic field, it is important to consider a thin plate with small Young's modulus and thickness. The effect on the acoustic field must be considered when the thickness exceeds 0.8 mm. The addition of the 0.28 mm thin plate in system with tapered stub resulted in a 7.8 W increase in acoustic power compared to that of system without the thin plate.