超声波强化热风干燥梨片的干燥特性

为探讨超声波对常规热风干燥的强化效应,本实验以梨片为研究对象,进行气介超声波强化热风干燥的研究。结果表明:超声波传播能量随超声波辐射距离的延长而显著衰减,缩短超声波辐射距离有利于提高超声波能量利用率及干燥速率。提高干燥温度及超声波功率均有利于提高干燥速率及缩短干燥时间,超声波对干燥速率的强化效应在干燥初期较为明显,但随物料含水率的下降而有所减弱。有效水分扩散系数的范围为3.21×10-10~7.43×10-10 m2/s,且随干燥温度及超声波功率的提高而增大。将气介超声波应用于梨片的热风干燥,可获得显著的强化效果,实现干燥速率的有效提高。

Drying Characteristics of Pear Slices during Ultrasound-Assisted Hot Air Drying

In this work, we examined the enhancing effect of air-borne ultrasound treatment on conventional hot air drying
of pear slices. The results showed that ultrasonic energy attenuated significantly with an increase in ultrasonic radiation
distance, and a reduction in ultrasonic radiation distance was beneficial to improve both ultrasonic energy efficiency and
drying rate. The drying rate was increased and the drying time was shortened by increasing the drying temperature and
ultrasonic power. The enhancing effect of ultrasound on drying rate was obvious in the initial drying period, but declined
with decreasing moisture content in samples. The values of effective moisture diffusivity ranged from 3.21 × 10-10 to
7.43 × 10-10 m2/s, which were increased significantly by increasing either drying temperature or ultrasonic power. Therefore,
air-borne ultrasound could notably reinforce traditional hot air drying of pear slices and increase the drying rate.