Thermophysical properties of fresh and dried white onion slices
1995
Rapusas, R.S. | Driscoll, R.H.
The variation of the specific heat, effective thermal conductivity and density of onion (Allium cepa L., cv. Southport White Globe) slices with moisture content at near ambient temperature was determined by the method of mixtures, the line heat-source probe and the liquid displacement method respectively. The specific heat, the effective thermal conductivity and the calculated effective thermal diffusivity were found to vary linearly with moisture content. The effective thermal conductivity of the onion slices did not change significantly in the measurement temperature range 30.7-33.0 degrees and the porosity range 0.09-0.27. None of the additive models tested accurately predicted the specific heat and the effective thermal conductivity of onion slices at different moisture contents The true density of the onion slices increased linearly from 1066-1416 kg/m3 as the slices were dried. The apparent density and internal porosity as a function of moisture content were correlated by third-order polynomials.
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