ARS | Publication request: Study of Temperature Dependence of Dielectric Properties of Bound Water in Grain and Seed at Microwave Frequencies

Submitted to: International Conference on Water and Irrigation
Publication Type: Abstract Only
Publication Acceptance Date: December 10, 2007
Publication Date: April 6, 2008
Citation: Trabelsi, S. 2008. Study of Temperature Dependence of Dielectric Properties of Bound Water in Grain and Seed at Microwave Frequencies. International Conference on Water and Irrigation.

Technical Abstract: The influence of temperature on dielectric properties of bound water in grain and seed was investigated through measurement of their dielectric properties at microwave frequencies over a wide temperature range between –80 oC and +24 oC. Free–space measurements were performed between 2 and 18 GHz on samples of different moisture contents. Cole-Cole plots reveal the existence of different distributions of relaxation times at different temperatures for samples of moisture contents around 15%. In contrast, Cole-Cole plots of data corresponding to samples with higher moisture contents (above 20%) indicate the existence of a single distribution of relaxation times for all temperatures. Plots at 9 GHz of the dielectric constant ,divided by bulk density, and of the loss factor, divided by bulk density, against temperature reveal almost linear increases with temperature with a characteristic slope change at around –20 oC. This observation suggests a freezing temperature of bound water at this temperature.