超声波联合热风干燥香菇片试验研究

Mushroom Slices Drying Using Hot-air Drying Coupled with Power Ultrasound

根据超声波强化传热传质的优点,并结合弯曲振动圆盘的声阻抗特性,设计了一种超声波联合热风干燥的设备,该设备实现了大功率超声与空气介质的有效耦合。通过对香菇片的干燥试验表明,在传统热风干燥中附加频率为20 kHz、功率为150 W、辐照圆盘直径为21 cm的超声波时,可使香菇片的干燥时间缩短至未加超声波前的50%,蒸发每千克水减少能耗约22%。超声波强化热风干燥的机理可能主要归因于超声的机械作用效应,有效强化了由水分内扩散控制的干燥过程。

With the aim to improve the efficiency of hot-air drying, a dryer of hot-air drying combined power ultrasound was explored according to the advantages of ultrasound on enhancing heat and mass transfer and the acoustic impedance of flexural vibrating plate. In this dryer, ultrasound could work effectively in air. The results of mushroom slices drying showed that the drying time using hot-air drying combined power ultrasound at 20 kHz, 150 W and diameter 20 cm plate was shorter as 50% as that using hot-air drying and the energy consumption per kilogram of water evaporation reduced by 22%. The mechanism of ultrasound which enhanced hot-air drying was discussed. It was possible attributed to ultrasound mechanical actions to enhance the moisture diffusion controlling step in the drying processing.