Reference Description of the study Frequency, power, intensity Best and/or interesting result obtained Bergles [63 ] Review article, heat transfer enhancement Cai et al. [71 ] Experimental, natural convection, acoustic cavitation, circular heated copper tube in water, brine and sugar water 18 kHz, 0–250 W Heat flux from cylinder: 132 W m−2 , ultrasonic intensity: 80 W cm−2 , enhancement up to 360%.
Fand and Kave [7 ] Acoustic streaming, convection heat transfer, heated cylinder 800 Hz–4800 Hz 3-fold increase in heat transfer rate Gould [70 ] Acoustic streaming, convection between metal and water or glycerin-water mixtures ? Up to 10-fold increase Hoshino and Yukawa [41 ] Experimental investigation, hot and cold cylinders, vertical standing waves, local and global coefficients in degassed water 28 kHz, 0.1–0.215 W cm−2 Local coefficient
at 0.125 W cm−2 , maximum at antinode and minimum at node Hoshino et al. [40 ] Free convective heat transfer from a heated wire 28 kHz Local coefficient
at 0.24 W cm−2 acoustic intensity, maximum at antinode and minimum at node Hyun et al. [8 ] Experiments and CFD simulations of acoustic streaming induced by flexural vibrations of a beam, cooling of a stationary beam above 28.4 kHz Temperature drop of 40°C in 4 min,
up to 157 W m−2 K−1 Iida et al. [39 ] Experimental, natural convection heat transfer from a fine cylinder to water, comparison convection coefficient and sound pressure profiles 28 kHz Augmentation ratio around 1.6 when ΔP > 0.02 MPa Komarov and Hirasawa [64 ] Standing and travelling sound waves in tubes, platinum wire 0.3–17.2 kHz
at 17.2 kHz, no gas flow and preheated wire temperature ~675 KLam et al. [77 ] Experimental study, saturated and air-dried wood cylinders heated in a water bath at 59.8°C with and without ultrasound 50–55 kHz, Significant influence of ultrasound on the temperature increase at the centre of cylinders Larson [62 ] Acoustic streaming around a sphere within a cylinder, cavitation, toluene, and water 20–1000 kHz, −2 Increase in Nusselt number up to about 4 times, but not sufficient to warrant the technology Lee and Loh [76 ] Acoustic streaming in a gap between heat source and transducer 30 kHz Heat transfer rate increased up to 75% Lee and Choi [72 ] Acoustic cavitation into CO2 saturated water 138 W Up to 369.5% turbulence intensity enhancement Loh et al. [9 ] Experiments and simulations (CFX4), flexural vibrations of a beam, acoustic streaming in air above (open) to cool a fixed beam 28.4 kHz Temperature drop of 40°C in 4 min, streaming velocity up to 2 m s−1 Markov et al. [75 ] Flowing molten metal (~1520°C) in a water-cooled tube 20 kHz Heat transfer coefficient as much as doubled Nakagawa [11 ] Experimental and computational results (CFX4), 4 vibrators to control acoustic streaming in a vessel containing silicon oil 1 MHz Maximum streaming velocity measured: 0.07 m s−1 , jet position modified Nakayama and Kano [38 ] Experiments, cylindrical glass vessel, distilled water, with or without glass beads 20 kHz, 0–140 W With glass beads, at saturation pressure 13.3 kPa,
increased up to 4 times Nomura and Nakagawa [15 ] Cooling a narrow surface, acoustic streaming and cavitation effects separated, water tank, experimental investigations 40 kHz, 600 W Acoustic streaming at 0.4 m s−1 ,
predicted with forced convection equations. Cavitation:
increased up to about 10 times Nomura et al. [16 ] Downward facing surface, ultrasound from below, experimental, cavitation, and acoustic streaming 60.7 kHz, 5–20 W Up to 10-fold increase in heat transfer coefficient, tap and degassed water Nomura et al. [26 ] Turbulence intensity measured experimentally, square channel, transducer at the bottom 25 kHz, 0–50 W Turbulence intensity 3 times larger with ultrasonic vibrations and up to 5 times locally Nomura et al. [66 ] Effect of ultrasonic frequency on downward facing and vertical surface 28 kHz (110 W), Around 2 or 3 times average increase in
Nomura et al. [67 ] Experimental, natural convection, obstacle in front of a heating surface (different materials), acoustic streaming 60.7 kHz, 5–20 W Up to 3 times with acrylic plate at 20 W, obstruction plates placed near the horn tip Richardson [69 ] Horizontal heated cylinder, horizontal and vertical sound fields, shadowgraphs 710 and 1470 Hz Local changes of boundary layer thickness and heat transfer enhancement Uhlenwinkel et al. [61 ] Experimental, gas vessel (air argon helium), resonant acoustic field, distance between transducers 20–200 mm 10 and 20 kHz Heat transfer enhancement up to 25 times at ambient pressure at about 0.9 MPa and 20 kHz Vainshtein et al. [12 ] Two horizontal plates at different temperatures, acoustic streaming in longitudinal direction 200 Hz–15 kHz, 140 and 145 dB Nu from 1 to 10, increase with frequency Yukawa et al. [65 ] Inclined copper plate in water 28 kHz, 0.1–0.48 W cm−2 Convection coefficient increased 6-fold at inclination 90°, intensity 0.48 W cm−2 Zhou et al. [74 ] Horizontal copper tube in water, acetone and ethanol, experimental study ? Maximum ratio of heat transfer enhancement: 3.95 with acetone, maximum source intensity, and close sound distance
