Influence of Frequency and Intensity of Bilateral Audible Sound Waves on Heat Transfer Performance of Air-to-air Heat Exchange Systems

To enhance the air heat transfer performance, this study applied the bilateral audible sound waves to an air-to-air heat exchanger. The effect of the frequency and intensity of sound waves on heat transfer performance was investigated from the viewpoint of flow instability and heat flux, and the sound power efficiency was also explored to reveal the efficiency of sound waves on the heat transfer performance. The results showed that the flow instability intensified with the increase in sound pressure level (SPL) and decrease in frequency, which was reflected by the distribution of turbulence kinetic energy. The change in sound waves has different effects on the turbulence kinetic energy at different locations, and the directivity distribution characteristics of the turbulence kinetic energy inside and outside the heat tube caused similar directivity distribution characteristics of the heat flux, in which the maximum value of the heat flux was located perpendicular to the flow direction. Additionally, the heat flux at different locations increased with an increase in SPL and a decrease in frequency. The heat transfer performance was relatively superior when the SPL was higher than 120 dB and the frequency was lower than 100 Hz, and a decrease in frequency could increase the sound power efficiency. This study can guide the application of sound waves in the heat transfer enhancement of air-to-air heat exchange systems. (c) 2022 Elsevier Ltd. All rights reserved.