Radical production inside an acoustically driven microbubble

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• 作者：Laura Stricker ; Detlef Lohse
• 关键词：Radicals ; Sonochemistry ; Ultrasound ; Microbubbles ; Vapor ; Stoichiometric
• 刊名：Ultrasonics Sonochemistry
• 出版年：2014
• 出版时间：January, 2014
• 年：2014
• 卷：21
• 期：1
• 页码：336-345
• 全文大小：824 K

文摘

The chemical production of radicals inside acoustically driven bubbles is determined by the local temperature inside the bubbles and by their composition at collapse. By means of a previously validated ordinary differential equations (ODE) model [L. Stricker, A. Prosperetti, D. Lohse, Validation of an approximate model for the thermal behavior in acoustically driven bubbles, J. Acoust. Soc. Am. 130 (5) (2011) 3243-3251], based on boundary layer assumption for mass and heat transport, we study the influence of different parameters on the radical production. We perform different simulations by changing the driving frequency and pressure, the temperature of the surrounding liquid and the composition of the gas inside the bubbles. In agreement with the experimental conditions of new generation sonochemical reactors, where the bubbles undergo transient cavitation oscillations [D. F. Rivas, L. Stricker, A. Zijlstra, H. Gardeniers, D. Lohse, A. Prosperetti, Ultrasound artificially nucleated bubbles and their sonochemical radical production, Ultrason. Sonochem. 20 (1) (2013) 510-524], we mainly concentrate on the initial chemical transient and we suggest optimal working ranges for technological applications. The importance of the chemical composition at collapse is reflected in the model, including the role of entrapped water vapor. We in particular study the exothermal reactions taking place in H₂ and O₂ mixtures. At the exact stoichiometric mixture 2:1 the highest internal bubble temperatures are achieved.