Method for the simultaneous and independent determination of moisture content and density of particulate materials from radio-frequency permittivity measurements
AssigneeThe United States of America as represented by the Secretary of Agriculture
InventorsStuart O. Nelson, Samir Trabelsi, Andrzej W. Kraszewski
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Abstract
A method for simultaneously and independently measuring moisture content and bulk density of particulate materials using radio-frequency measurements allowing for on-line, real-time monitoring and control. Moisture and density are determined by measurements of complex permittivities. This method is based on the use of the dielectric properties of the materials for density and water content determination.
Claims17
A method for determining moisture content of a material comprising
- (a) locating a material in a radio-frequency measuring device comprising a source, sensing elements and a radio-frequencies properties measuring unit,
- (b) measuring the radio-frequency properties of said material,
- (c) calculating the dielectric constant .epsilon.' and the loss factor .epsilon.", and
- (d) determining percent moisture content, M% , of said material using .epsilon.' and .epsilon." obtained in step (c) using a calibration equation as follows:
- ##EQU32## wherein a.sub..function., B and a are constants specific to said material, and .zeta. is a density-independent function determined by the following equation:
- ##EQU33##
A method for determining bulk density of a material comprising (a) locating a material in a radiofrequency measuring device comprising a source, sensing elements and a radio-frequency properties measuring unit,
- (b) measuring the radio-frequency properties of said material,
- (c) calculating the dielectric constant .epsilon.' and the loss factor .epsilon.", and
- (d) determining bulk density, .rho., of said material using .epsilon.' and .epsilon." obtained in step (c) using the following equation:
- ##EQU34## wherein k, in g.sup.-1 .multidot.cm.sup.3 and a.sub..function. are constants specific to said material.
A method for determining moisture content and bulk density of a material comprising
- (a) locating a material in a radio-frequency measuring device comprising a source, sensing elements, and a radio-frequency properties measuring unit,
- (b) measuring the radio-frequency properties of said material,
- (c) calculating the dielectric constant .epsilon.' and the loss factor .epsilon.",
- (d) determining percent moisture content, M% , of said material using .epsilon.' and .epsilon." obtained in step (c) using a calibration equation as follows:
- ##EQU35## wherein a.sub..function., B and a are constants specific to said material, and .zeta. is a density-independent function determined as follows:
- ##EQU36## (e) determining bulk density, .rho., of said material using .epsilon.' and .epsilon." obtained in step (c) using the following:
- ##EQU37## wherein k , in g.sup.-1 .multidot.cm.sup.3, and a.sub..function. are all constants specific to said materials;
- and percent moisture content and bulk density are simultaneously and independently measured.
A method for determining percent moisture content of a material comprising
- (a) locating a material in a free-space transmission microwave system comprising a synthesized sweeper, a transmitting antenna, a receiving antenna and a vector network analyzer,
- (b) measuring complex transmission coefficient,
- (c) calculating dielectric constant .epsilon.' and .epsilon.", and
- (d) determining percent moisture content, M% , of said material using .epsilon.' and .epsilon." obtained in step (c) using a calibration equation:
- ##EQU38## a.sub..function., B and a are constants specific to said material, and .zeta. is a density-independent function determined as follows:
- ##EQU39##
Dependencies are inferred from the claim text.