García-Pérez J V, Cárcel J A, de la Fuente-Blanco S, Riera-Franco de Sarabia E
Food Technology Department, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain.
Ultrasonics. 2006 Dec 22;44 Suppl 1:e539-43. doi: 10.1016/j.ultras.2006.06.059. Epub 2006 Jul 12.
The application of high power ultrasound for dehydration of porous materials may be very effective in processes in which heat-sensitive materials such as foodstuffs have to be treated. In fact, high-intensity ultrasonic vibrations are capable of increasing heat and mass transfer processes in materials. The application of ultrasonic energy can be made alone or in combination with other kind of energy such as hot-air. In this case, ultrasound helps in reducing temperature or treatment time. The aim of this work is to study the effect of air flow rate, ultrasonic power and mass loading on hot-air drying assisted by a new power ultrasonic system. The drying chamber is an aluminium vibrating cylinder, which is able to create a high intensity ultrasonic field in the gas medium. To that purpose the chamber is driven at its centre by a power ultrasonic vibrator at 21.8 kHz. Drying kinetics of carrot cubes and lemon peel cylinders were carried out at 40 degrees C for different air velocities, with and without ultrasound. The results show that the effect of ultrasound on drying rate is affected by air flow rate, ultrasonic power and mass loading. In fact, at high air velocities the acoustic field inside the chamber is disturbed and the effect of ultrasound on drying kinetics diminishes.
高功率超声在多孔材料脱水方面的应用，对于诸如食品等热敏材料的处理过程可能非常有效。实际上，高强度超声振动能够增强材料中的传热和传质过程。超声能量的应用可以单独进行，也可以与其他能量形式（如热风）结合使用。在这种情况下，超声有助于降低温度或缩短处理时间。本研究的目的是探讨气流速率、超声功率和物料装载量对新型功率超声系统辅助热风干燥的影响。干燥室是一个铝制振动圆筒，能够在气体介质中产生高强度超声场。为此，该圆筒在其中心由一个21.8kHz的功率超声振动器驱动。在40℃下，针对不同风速，对胡萝卜块和柠檬皮圆筒进行了有无超声作用下的干燥动力学实验。结果表明，超声对干燥速率的影响受气流速率、超声功率和物料装载量的影响。实际上，在高风速下，干燥室内的声场受到干扰，超声对干燥动力学的影响减弱。
