Effects of structural properties change during drying on thermal conductivity of fruits and vegetables
2004
Souma, S. (Chiba Univ. (Japan)) | Tagawa, A. | Iimoto, M.
The effects of structural properties and moisture content on the thermal conductivity of fruits and vegetables were investigated. The transient heat probe method using twin probe was used for the determination of thermal conductivity. Thermal conductivity at initial moisture content of eight kinds of fruits and vegetables was measured at 10 deg C. Especially, thermal conductivity of radish, ranging in moisture content from 0.0 to 94.6% (w.b.), was measured at 10 to 40 deg C. Structural properties of radish, such as apparent density, true density and internal porosity, were investigated at several moisture content. The apparent density and the dried solid density were measured by liquid displacement method, therefore, true density and internal porosity were calculated, respectively. Assuming three-phase system consisting of air, water, and solid, each volume fraction was calculated. Measured results of thermal conductivity were compared with the heat conduction model proposed by Rahman, which involve temperature, moisture content, volume fraction, and thermal conductivity of each component. Measured results were agreed well with the predicted results by Rahman's model.
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