Abstract
The aim of this study is to determine the dielectric constant of woody biomass at different water contents and describe its behavior with a dielectric mixing model. The use of the model for determination of water content is also verified. Dielectric constants were calculated from the travel times of electromagnetic waves with a center frequency of 555 MHz through collected biomass samples. The power law, Maxwell–Garnett, and Polder van Santen mixing models were applied to the experimental data. In the models, biomass was considered as a mixture of three phases: a solid solution composed of wood cellular material and bound water, free water, and air. The experimental data was found to be better described by the Maxwell–Garnett model. The use of this model along with an independent validation set for the determination of volumetric water content resulted in a root mean square error of prediction of 0.03 within the investigated volumetric water content range of 0.07–0.29.
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Acknowledgments
The authors would like to thank Värmeforsk—the Swedish district heating association, for financing the project in which this study is included and the combined heat and power plants Mälarenegi in Västerå s and Eskilstuna Energi och Miljö in Eskisltuna, Sweden, for providing the biofuel samples used in this study.
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Paz, A., Thorin, E. & Topp, C. Dielectric mixing models for water content determination in woody biomass. Wood Sci Technol 45, 249–259 (2011). https://doi.org/10.1007/s00226-010-0316-8
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DOI: https://doi.org/10.1007/s00226-010-0316-8