Document Type : Research Article
Authors
Tarbiat Modares University
Abstract
In this study thin layer drying of corn in a convective dryer was investigated at air temperatures of 50, 60 and 70ºC and air flow rates of 1, 1.4 and 1.8 kg min-1. Experiments were performed in Completely Randomized Design (CRD). The effect of air temperature and flow rate on drying time, drying rate, effective diffusivity coefficient and activation energy were studied. Results showed that the effects of temperature and flow rate on drying process were significant. Increasing the air temperature from 50 to 70 ˚C, caused 31.7 percent decrease in drying time and change of air flow rate from 1 to 1.8 kg min-1 reduced drying time 27 percent in average. The effective diffusivity coefficient and activation energy varied from 3.47258 ×10-11 to 7.34352×10-11 m2 s-1. and 13.761 to 16.193 kJ mol-1, respectively depending on the drying treatments. The Logarithmic model was found to be in a better agreement with experimental data compared with other models. The minimum value of specific energy requirement (3.61 kWh kg-1) was obtained at a drying air temperature of 50 °C and air flow rate of 1 kg min-1, whereas the corresponding parameters for the maximum value (5.34 kWh kg-1) were determined as 70 °C and air flow rate 1.8 kg min-1.
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