Department of Agricultural Machinery Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran.
Department of Irrigation and Drainage Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran.
J Food Sci Technol. 2013 Aug;50(4):667-77. doi: 10.1007/s13197-011-0399-8. Epub 2011 May 28.
This study investigated thin layer drying of squash seeds under semi fluidized and fluidized bed conditions with initial moisture content about 83.99% (d.b.). An experimental fluidized bed dryer was also used in this study. Air temperature levels of 50, 60, 70 and 80 °C were applied in drying samples. To estimate the drying kinetic of squash seed, seven mathematical models were used to fit the experimental data of thin layer drying. Among the applied models, Two-term model has the best performance to estimate the thin layer drying behavior of the squash seeds. Fick's second law in diffusion was used to determine the effective moisture diffusivity of squash seeds. The range of calculated values of effective moisture diffusivity for drying experiments were between 0.160 × 10(-9) and 0.551 × 10(-10) m(2)/s. Moisture diffusivity values decreased as the input air temperature decreased. Activation energy values were found to be between 31.94 and 34.49 kJ/mol for 50 °C to 80 °C, respectively. The specific energy consumption for squash seeds was calculated at the boundary of 0.783 × 10(6) and 2.303 × 10(6) kJ/kg. Increasing in drying air temperature in different bed conditions led to decrease in specific energy value. Results showed that applying the semi fluidized bed condition is more effective for convective drying of squash seeds. The aforesaid drying characteristics are useful to select the best operational point of fluidized bed dryer and to precise design of system.
本研究在初始含水量约为 83.99%（干基）的半流化和流化床上对南瓜籽进行薄层干燥。本研究还使用了实验流化床干燥器。在干燥样品时，应用了 50、60、70 和 80°C 的空气温度水平。为了估计南瓜籽的干燥动力学，使用了七个数学模型来拟合薄层干燥的实验数据。在所应用的模型中，双项模型在估计南瓜籽的薄层干燥行为方面表现最佳。菲克第二定律在扩散中用于确定南瓜籽的有效水分扩散系数。计算的干燥实验有效水分扩散系数值在 0.160×10(-9)和 0.551×10(-10)m(2)/s 之间。随着输入空气温度的降低，水分扩散系数值降低。在 50°C 至 80°C 之间，活化能值分别为 31.94 至 34.49 kJ/mol。南瓜籽的比能耗计算值在 0.783×10(6)和 2.303×10(6)kJ/kg 的边界处。在不同的床层条件下提高干燥空气温度会导致比能耗值降低。结果表明，采用半流化床条件对流化床干燥南瓜籽更有效。上述干燥特性有助于选择流化床干燥器的最佳操作点，并精确设计系统。
