| Ultrasonic wave is a kind of mechanical wave with high frequencies. As a form of energy, ultrasonic vibration, ultrasonic cavitation, and the various effects generated by interaction between cavitation bubbles and liquid in the the liquid showed a very broad prospect in the physical, chemical and biological sciences of basic research and applied technology development. Ultrasonic vibration, ultrasonic cavitation can effectively strengthen mass transfer, heat transfer, change balance of physical chemistry, and accelerate the rate of a chemical reaction.From theory and numerical simulation of the ultrasonic cavitation, this article mainly studies bubble dynamics and designs extraction device, and the main work and related conclusions are as follows:(1) Discuss ultrasonic field strengthening mass transfer process. Based on the theory that ultrasonic cavitation bubbles expand and contract under the action of the ultrasonic field, the bubble can be treated as a oscillator in liquid load. From derivation method of Rayleigh equation to be used, the kinetic model of bubbles in ultrasonic field of one frequency and two frequencies is deduced, dynamic effects of in the two cases are analyzed using numerical simulation with Matlab, and the results show that ultrasonic effect double-frequency cavitation bubble brings about is stronger than that monophonic frequency cavitation under the same conditions, due to which dual-frequency ultrasound can be used to enhance mass transportation of Chinese herbal medicine.(2) according to Fick first law and herbal leaching mechanism, combining Titus mechanism ultrasonic cavitation effect, the influence of mechanical effect on extraction system, the dynamics model of ultrasound improved extraction Chinese herbals is established and relationship between time, ultrasonic sound pressure amplitudes and leaching quantity of effective component is discussed, proved by the experimental data and simulated numerically. Studies show that, the relationship from the theory between ultrasonic extraction yield time, the ultrasonic sound pressure amplitude, experiment data and simulation results are basically in agreement. (3) Based on advantages of ultrasonic extraction technology used in traditional Chinese medicine auxiliary in of extracting effective components, in order to expand ultrasound practical application value, in theory research, according to the acoustic propagation and ultrasonic effects, related to piping transmission characteristics of Chinese traditional medicine extraction equipment, the double system of dual-frequency is designed, analyzed and discussed. It shows that the equipment is proper, distinctive and can be applied to industry more. |
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