红外联合气体射流冲击方法缩短哈密瓜片的干燥时间

    Shorting drying time of Hami-melon slice using infrared radiation combined with air impingement drying

    • 摘要: 为了缩短哈密瓜片干制时间,应用中短波红外联合气体射流冲击方法干燥哈密瓜片,研究了干燥温度(50、55、60、65、70、75和80℃)、辐射距离(80、120和160 mm)和切片厚度(3、5、7、9和11 mm)对哈密瓜片干燥动力学、水分有效扩散系数、干燥活化能的影响。试验结果表明:与其他干燥技术相比,中短波红外联合气体射流冲击干燥哈密瓜片的干燥时间大幅缩短,约为2~3.5 h;哈密瓜片整个干燥过程属于降速干燥,通过费克第二定律求出了干燥过程中水分有效扩散系数在10.65×10-10~33.76×10-10 m2/s和8.06×10-10~39.97×10-10 m2/s的范围内分别随着干燥温度和切片厚度的增大而增大;通过阿尼乌斯公式计算出了干燥活化能为7.788 kJ/mol,表明中短波红外联合气体射流冲击干燥哈密瓜片时,启动干燥所需能量较低,水分脱除较为容易;哈密瓜片表面温度的动力曲线表明,中短波红外联合气体射流冲击干燥中能量直接与水分耦合,使物料在中前期干燥过程中温度迅速上升,加速了干燥进程。该研究为哈密瓜片中短波红外联合气体射流冲击干燥技术的应用提供了理论依据和技术支持。

       

      Abstract: Abstract: In order to reduce the drying time, the middle short-wave infrared radiation combined with air impingement drying was used to dry Hami-melon slices in this study. The effects of drying temperature of 50, 60, 65, 70, 75, and 80℃, radiation distance of 80, 120, and 160 mm, and sample thickness with 3, 5, 7, 9, and 11 mm, moisture effective diffusivity, and drying activation energy of Hami-melon slices were investigated through a series of experiments. Results indicated that the drying time of Hami-melon slices by infrared combined with air impingement drying was about 2-3.5 h. The drying time was decreased when compared with other drying technologies. The whole drying process occurred in the falling rate drying stage. The moisture effective diffusivity determined by Fick's second law varied from 10.65×10-10 to 33.76×10-10m2/s and from 8.06×10-10 to 39.97×10-10m2/s with increasing drying temperature and sample thickness, respectively. The drying activation energy was 7.788kJ/mol calculated based on Arrhenius equation. The energy needed to trigger drying is very small, drying can be operable easily using the middle short wave radiation combined with air impingement drying technology. The kinetics of surface temperature changes indicated that it increased quickly in the initial and middle drying stages and the drying process was accelerated due to the energy directly combined with water. This paper provides theoretical background and technical information for applying the middle short wave infrared combined with air impingement drying on Hami-melon slices.

       

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