Acoustically enhanced heat transport

Abstract

We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10(6) Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξs ∼ 10(-9) m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξs ∼ 10(-8) m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10(-8) m with 10(6) Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.

Enhancing rate of water absorption in seeds via a miniature surface acoustic wave device

“…In this work, the treatment does not induce acoustic cavitation. Based on the power and the frequency of the SAW, although the acoustic pressure amplitude should be of the order of 10 6 Pa [12], as filtered water is used, the threshold for acoustic cavitation is as high as 10 7 Pa [11]. Additionally, unlike the high-power low-frequency ultrasound technique in which seeds are fully soaked in water, in our approach, the seeds are only partially in contact with water, thus reducing the amount of water needed in the process.…”

Thermal performance enhancement in heat exchangers using active and passive techniques: a detailed review

“…The performance of the absorber plate was significantly improved with increasing number of electrodes. The phenomenon of HTE due to a sound wave in the nucleate boiling regime was explained by Ang et al [45]. The experimentation revealed that enhancement in thermal transport occurs at low-, moderate-, and high-frequency sound waves.…”