Dehane Aissa, Merouani Slimane, Hamdaoui Oualid, Alghyamah Abdulaziz
Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, Badji Mokhtar - Annaba University, P.O. Box 12, 23000 Annaba, Algeria.
Laboratory of Environmental Process Engineering, Department of Chemical Engineering, Faculty of Process Engineering, University Salah Boubnider-Constantine 3, P.O. Box 72, 25000 Constantine, Algeria.
Ultrason Sonochem. 2021 May;73:105498. doi: 10.1016/j.ultsonch.2021.105498. Epub 2021 Feb 20.
The present study treats the effects of mass transport, heat transfer and chemical reactions heat on the bubble dynamics by spanning a range of ambient bubble radii. The thermodynamic behavior of the acoustic bubble was shown for three wave frequencies, 355, 515 and 1000 kHz. The used acoustic amplitude ranges from 1 to 3 atm. It has been demonstrated that the ambient bubble radius, R, of the maximal response (i.e., maximal bubble temperature and pressure, T and P) is shifted toward lower values if the acoustic amplitude (at fixed frequency) or the ultrasonic frequency (at fixed amplitude) are increased. The range of the ambient bubble radius narrows as the ultrasonic frequency increases. Heat exchange at the bubble interface was found to be the most important mechanism within the bubble internal energy balance for acoustic amplitudes lower than 2.5 and 3 atm for ultrasonic frequencies of 355 and 515 kHz, respectively. For acoustic amplitudes greater or equal to 2.5 and 3 atm, corresponding to 355 and 515 kHz, respectively, mass transport mechanism (i.e., evaporation and condensation of water vapor) becomes dominant compared to the other mechanisms. At 1000 kHz, the mechanism of heat transfer persists to be dominant for all the used acoustic amplitudes (from 1 to 3 atm). Practically, all the above observations were maintained for bubbles at and around the optimum bubble radius, whereas no significant impact of the three energetic mechanisms was observed for bubbles of too lower and too higher values of R (limits of the investigated ranges of R).
本研究通过涵盖一系列环境气泡半径，探讨了质量传输、热传递和化学反应热对气泡动力学的影响。展示了三种波频率（355、515和1000kHz）下声泡的热力学行为。所使用的声压幅值范围为1至3个大气压。结果表明，如果增加声压幅值（在固定频率下）或超声频率（在固定幅值下），最大响应（即最大气泡温度和压力，T和P）的环境气泡半径R会向较低值偏移。随着超声频率的增加，环境气泡半径的范围变窄。对于355kHz和515kHz的超声频率，分别在低于2.5和3个大气压的声压幅值下，发现气泡界面处的热交换是气泡内能平衡中最重要的机制。对于分别对应于355kHz和515kHz的大于或等于2.5和3个大气压的声压幅值，与其他机制相比，质量传输机制（即水蒸气的蒸发和凝结）变得占主导地位。在1000kHz时，对于所有使用的声压幅值（从1到3个大气压），热传递机制仍然占主导地位。实际上，上述所有观察结果对于处于最佳气泡半径及附近的气泡都成立，而对于R值过低和过高（所研究的R范围的极限）的气泡，未观察到这三种能量机制有显著影响。
