Thermophysical parameters of chosen granular samples
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Faculty of Agricultural Engineering, Department of Physics, University of Agriculture, Tr. A. Hlinku 2, 949 76, Nitra, Slovakia
Int. Agrophys. 2005, 19(3): 203–207
This article deals with the thermophysical properties of granary mass. It is necessary to know the thermophysical parameters of granular mass to ensure the quality of the technological processes. Granular mass is composed as a complex of specific kinds of grains. It is a non-uniform material with both microscopic and macroscopic structures. Biophysical and physiological processes are realized within grains. Heat transfer cannot be isolated from the solid transfer and from the heat-moisture transfer. It means that specification of granular mass and granular fragments is difficult to determine. We researched the thermophysical properties of granular mass. Thermophysical parameters were measured by the Isomet instrument (made by the Applied Precision Comp.). It is used for quick and exact measurement of thermophysical parameters of various materials. Measurements were performed with a spike probe with the range of thermal conductivity of 0.015-0.2 Wm-1K-1. The spike probe was inserted into the analysed material. Heat was generated by the spike probe used. The time process of temperature which is related to the thermophysical parameters of samples was analysed. The relations of thermal conductivity and thermal diffusivity to the temperature of chosen samples (wheat, malt barley and colza) were measured first. The moisture content of samples during the measurements was constant 6.5%. All the measurements were realized at room temperature. Because moisture content is one of the most important parameters which determine the thermophysical parameters of biological materials, we made a second series of measurements of the relations of thermal conductivity and thermal diffusivity to the moisture content.