| Summary: | 碩士 === 國立中興大學 === 農業機械工程學系 === 87 === This study mainly used air with six temperatures 25, 32, 35, 38, 40 and 45℃ to process the drying tests of garlic. The experimental results show that the condition to determine the moisture content of garlic is 130℃ and 72 hours of dehydration. The best drying temperature of air is 38℃ with the average relative humidity 24.71% in the drying process. The drying time for obtaining the standard stored products as moisture content of 250%(d.b.) are 15 days for Shen Gang and 13 days for Mai Liau, respectively. The drying time for attending the change of moisture content in 24 hours less than 1%(d.b.) are respectively of 39 days for Shen Gang and 43 days for Mai Liau.
Newton’s, modified Newton’s, Page’s and Diffusion models were used to simulate the drying process of garlic and to investigate the fitting agreement of the moisture content data obtained from each drying condition. Analyzing and comparing the statistical values obtained from regression analysis, two values such as the coefficient of determination R2(R square) and the full set standard error of estimate of the predicted values of moisture content to the measured values showed that Diffusion model was optimal and had the best fitting agreement.
The drying constant K and the modified diffusion coefficient Dr obtained, respectively, by applying the dynamic equilibrium moisture content value Med into Newton’s, modified Newton’s, Page’s and Diffusion models, were both reduced as the drying time increased. Both correlative equations constructed for the drying constant K and the modified diffusion coefficient Dr were the polynomial equations of third order in temperature T(℃) and first order in relative humidity RH(%). While applying the static equilibrium moisture content value Me into the above models described, the drying constant K exclusive of the case obtained from Page’s model, and the modified diffusion coefficient Dr were also decreased as the drying time increased. After analyzing and comparing Newton’s, modified Newton’s and Diffusion models, the predicted values obtained by using Me value are worse than those obtained by Med value. Therefore, this study showed that the dynamic equilibrium moisture content value Med applied in drying models could achieve better predicting characteristics.
|
|---|
