Experimental study of the effects of ultrasonic waves on surface sediments in pool boiling

Increasing heat transfer and preventing sedimentation in equipment have always attracted the attention of engineers. In this work, the variations of salt concentration were effective on bubble diameter, departure frequency and generation points and its sediments acted as a heat transfer resistance. Therefore, first, the effect of ultrasonic waves on salt sedimentations in pool boiling was investigated. The results revealed that the ultrasonic waves had positive effect by suspending the soluble particles in the fluid and preventing them from precipitating on the surface of heat transfer. Increasing turbulences and perturbations due to changes in bubble dynamic and cavitation phenomenium, led to improve the heat transfer coefficient, significantly. The role of roughness on the surface heat transfer in bubble production was other investigation of the work. Bubble production by increasing the roughness with ultrasonic wave’s irradiation had direct and important effects on enhancing the heat transfer. Finally, salt and nanofluid sediments were compared. The nanoparticles precipitate faster and more easily under the bubble layer, but less in the salt solution if its dissolution is maintained. The ultrasonic waves were employed at three powers of 30%, 60% and 90%. Finally, the heat transfer coefficient and bubble departure diameter increased as 8.43% and 7.54%, respectively. In addition, the sedimentation decreased by 37.19%. As a result, the waves reduced their deposition by preserving salt dissolution.