Heat transfer enhancement using 2 MHz ultrasound

Odin Bulliard-Sauret (1) , Sébastien Ferrouillat (1) , Laure Vignal (1) , Alain Memponteil (2) , Nicolas Gondrexon (3)

1 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]
2 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
3 LRP - Laboratoire Rhéologie et Procédés

The present work focuses on possible heat transfer enhancement from a heating plate towards tap water in forced convection by means of 2 MHz ultrasound. The thermal approach allows to observe the increase of local convective heat transfer coefficients in the presence of ultrasound and to deduce a correlation between ultrasound power and Nusselt number. Heat transfer coefficient under ultrasound remains constant while heat transfer coefficient under silent conditions increases with Reynolds number from 900 up to 5000. Therefore, heat transfer enhancement factor ranges from 25% up to 90% for the same energy conditions (supplied ultrasonic power = 110 W and supplied thermal power = 450 W). In the same time cavitational activity due to 2 MHz ultrasound emission was characterized from mechanical and chemical viewpoints without significant results. At least, Particle Image Velocimetry (PIV) measurements have been performed in order to investigate hydrodynamic modifications due to the presence of 2 MHz ultrasound. It was therefore possible to propose a better understanding of heat transfer enhancement mechanism with high frequency ultrasound.

Mots clés: Forced convection; Heat transfer enhancement; 2 MHz ultrasound; Acoustic streaming; PIV; Turbulence

Domaines: Thermique [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Acoustique [physics.class-ph]

Odin Bulliard-Sauret, Sébastien Ferrouillat, Laure Vignal, Alain Memponteil, Nicolas Gondrexon. Heat transfer enhancement using 2 MHz ultrasound. Ultrasonics Sonochemistry, 2017, 39, pp.262-271. ⟨10.1016/j.ultsonch.2017.04.021⟩. ⟨hal-01664608⟩