Methods of Determination for Effective Diffusion Coefficient During Convective Drying of Clay Products
© 2012 Vasic et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Methods of Determination for Effective Diffusion Coefficient During Convective Drying of Clay Products
Performance evaluation of hybrid thin layer solar tunnel-windmill dryer in the drying of brined and non-brined Tafi (Siganussutor) Fish
Studies were carried out to evaluate the performance of hybrid solar tunnel-windmill dryer in thin layer drying of brined and non-brined Tafi ( Siganus spp .) fish. The fish were, eviscerated, and split into pieces of approximately 6cm by 4cm by 5mm was soaked in brine at 0 and 5% concentrations. The samples were dried in the dryer for 44 hours. The moisture content of the drying fish was evaluated by the AOAC oven drying procedure. In addition, analysis was carried out to establish the best thin layer drying model that describes the drying of fish in the hybrid wind-solar tunnel dryer. The moisture content of the drying fish was found to reduce linearly from 4.2 and 3.9kg/kg ( db ), respectively for brined and non-brined fish to 0.8kg/kg ( db ). A two way Students t -test did not establish any significant difference in the drying of salted and unsalted fish (t stat =1.4032, t crit, 5% =2.0687). Further, the page thin layer drying model was found to be the best model describing the thin layer drying of Tafi fish in the hybrd solar tunnel-windmill dryer (R 2 =0.9655 and 0.09434; RMSE=0.0539 and 0.0840 for unsalted; c 2 =0.0032 and 0.0077, for salted and unsalted fish, respectively). These results provide useful information in the modelling and design of solar drying systems for the drying of Tafi fish. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ 
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Factors affecting water uptake of rice grain during soaking
The soaking process of rice (raw, dehulled or bran and white) in plain water was investigated between 25°C and 65°C. The corresponding effective diffusion coefficients were evaluated by fitting experimental absorption curves to Fick's second law for diffusion out of sphere. Effective diffusion coefficients for raw, brown and white rice varied between 1.56×10−11 and 7.20×10−11 m2 s−1; 2.22×10−11 and 8.82×10−11 m2 s−1 and 20.5×10−11 and 47.0×10−11 m2 s−1, respectively, for the temperature range investigated. The amount of total solids leached increased with the increase of temperature and time; the highest corresponded to white rice. The rates of absorption of raw rice in aqueous solutions of ClH, CH3COOH and PO4H3 at 25°C were quite similar and much lower than those in plain water at the same temperature. Raw rice soaked in NaOH aqueous solutions and Na2CO3 aqueous solutions gave, in terms of the diffusion coefficients, higher absorption rates than raw rice soaked in plain water. Absorption rates for raw rice soaked in NaOH concentrations were higher than those found in Na2CO3 concentrations. When raw rice was soaked in NaOH aqueous solution at 55°C the rate of absorption was coincident to that found during soaking of dehulled rice in plain water.