Dielectric properties of hops - an effect of bulk density

Jakub Lev and František Kumhála
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Jakub Lev: Department of Physics,
František Kumhála: Departmen of Agricultural Machines, Faculty of Engineering, Czech University of Life Sciences Prague, Czech Republic Corresponding auhtor: kumhala@tf.czu.cz

Research in Agricultural Engineering, 2017, vol. 63, issue SpecialIssue, S18-S23

Abstract: Continuous detection of basic physical properties of freshly picked and cleaned wet hop cones would be very helpful for better control and automation of harvesting processes. That is why the main aim of this article was to determine the effects of bulk density changes on dielectric properties of freshly picked hop cones. Relative permittivity and loss factor were measured using a newly developed capacitance measuring device. A strong linear correlation between fresh hops relative permittivity and bulk density was found. This finding could be used e.g. for consequent hop drying process control. Significant differences between tested hop varieties were observed for both relative permittivity and loss factor measurements. These differences cannot be explained only by a slightly different moisture content of the measured varieties and ambient temperature changes. Measured material loss factor was only slightly affected by bulk density changes. However, relative permittivity was affected by bulk density changes significantly. These facts could be used for other properties of wet hop cones estimation.

Keywords: fresh hop cones; relative permittivity; loss factor; capacitance sensor (search for similar items in EconPapers)
Date: 2017
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Persistent link: https://EconPapers.repec.org/RePEc:caa:jnlrae:v:63:y:2017:i:specialissue:id:34-2017-rae

DOI: 10.17221/34/2017-RAE

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