Thermophysical properties and their application to numerical models for heat and moisture migration in bulk storage of soyameal in the humid tropics
2002
Ricarte, M.I.
This study was conducted to determine the thermophysical properties (moisture sorption isotherm, specific heat, thermal conductivity, bulk density, porosity, and caking) of soyameal; and to apply these properties to create a heat transfer model and the corresponding moisture migration model of the bulk stored product. Two hopper-bottom bins were filled with soyameal and were used in validating the models. Moisture sorption isotherm was determined using three sets of jars with 11%, 32%, 53%, 75% and 90% controlled relative humudity. Each set was exposed to a constant temperature of 15 deg C, 25 deg C, and 35 deg C, and it was determined that the Guggenheim, Anderson and Deboer (GAB) model gave the best-fit equations. The phenomenon of caking was observed at when the moisture content reaches 14% db. The specific heat was determined using a calorimeter; the thermal conductivity was obtained using a modified fitch set-up, the bulk density was determined using a bulk density apparatus, and the porosity was measured by volumetric method. The transient heat transfer model was developed using explicit finite difference method and it showed that heat generation and conduction are the main driving force for heat transfer in bulk-stored soyameal. The GAB model developed in the MSI [moisture sorption isotherm] study was the basis for the moisture migration model and it showed that the moisture tends to be deposited in the cooler regions of the bin. The actual storage experiment showed that both heat transfer and moisture migration models were acceptable in predicting the temperature and moisture content of bulk-stored soyameal, respectively
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