【摘要】 对超声波作用下苹果片预干燥过程进行了试验研究,分析了超声声强对样品预干燥速率的影响.建立了超声波预干燥过程的数学模型,模型中引入修正系数γ来反映超声波对样品内部水分扩散系数的影响.结合试验中所得样品含水率数据,计算出不同超声强度对应的修正系数,并拟合出修正系数与超声强度的关系曲线.研究结果表明,超声波有效强化了苹果片的预干燥过程,当超声强度为1.0 W/cm2时,干燥速率提高了67.2%.超声波对样品内部水分扩散系数的影响随着超声强度的增大而逐渐增强,且修正系数与声强呈线性递增关系.试验过程中发现,超声热效应引起的样品表面及中心的温度变化很小,超声强度为1.0 W/cm2时,样品平均温升小于2℃.更多还原

【Abstract】 The experiment on pre-dehydration process of apple slice under ultrasound radiation was performed,and the effect of ultrasonic intensity on pre-dehydration rate of sample was analyzed.A mathematical model for ultrasonic pre-dehydration process was established.In this model,the correction coefficient γ was employed for considering the effect of ultrasound on moisture diffusion coefficient in sample,and it was numerically calculated based on the experimental data of water content in sample under different acoustic intensity.The relation curve of ultrasonic intensity to correction coefficient was also fitted.The results show that ultrasound effectively enhances the moisture transfer process in apple slice,the dehydration rate increases 67.2% at ultrasonic intensity of 1.0W/cm2.The effect of ultrasound radiation on moisture diffusion coefficient intensifies gradually with increasing of ultrasonic intensity and the correction coefficient increases linearly with ultrasonic intensity.In the experimental process,it is observed that temperature rising in the center and surface of sample caused by the thermal effect of ultrasound is unobvious,and the average temperature rise of sample is no more than 2℃ at the ultrasonic intensity of 1.0W/cm2.更多还原