Moisture Meter for Bulk Solids Using Complex Dielectric Permittivity
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Solution Overview
Problem
Existing moisture meters for bulk materials face limitations in measuring moisture content accurately in materials like crushed stone and sand due to signal attenuation and reflection issues, and are not universal as they require specific impedance matching and structural complexity, which restricts their application to varying materials and moisture levels.
Innovation Solution
A moisture meter design that includes a metallic rod with adjustable installation configurations within the hopper, a measuring cell with resistors and detectors to measure real and imaginary parts of complex dielectric permittivity, and a temperature sensor to ensure accurate moisture content determination, independent of material density and moisture levels, with a simplified design that reduces mechanical stress and error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transition horns with dielectric plates are used to ensure impedance matching, then measurement accuracy is improved, but device complexity and mechanical strength deteriorate
Solution Approach 1:
The patent removes the transition horns and dielectric plates from the measurement system. Instead of using complex impedance matching structures, the invention directly measures the complex dielectric permittivity of the material using a simplified probe configuration, thereby eliminating the matching components that added complexity and mechanical weakness.
Solution Approach 2:
The patent replaces the mechanical impedance matching system (transition horns with dielectric plates) with an electrical measurement approach. By directly measuring complex dielectric permittivity at the probe input, the system substitutes mechanical impedance adaptation with electrical parameter measurement, achieving accuracy without mechanical complexity.
2Measurement precision
If transition horns are designed for specific materials, then measurement accuracy for those materials is improved, but adaptability to different materials deteriorates
Solution Approach 1:
The patent creates a universal measurement system that can measure complex dielectric permittivity for any bulk material without requiring material-specific configuration. The probe structure and measurement method are designed to be material-agnostic, allowing the same device to accurately measure different materials (grains, sand, crushed stone, etc.) with varying moisture contents and physical properties.
Solution Approach 2:
The patent measures both real and imaginary parts of complex dielectric permittivity across a range of frequencies, allowing the system to adapt to different materials through parameter variation rather than structural modification. This enables universal measurement capability while maintaining accuracy for diverse materials.
3Reliability
If horn sizes are fixed for impedance matching, then matching is achieved for specific conditions, but measurement reliability for varying moisture levels deteriorates
Solution Approach 1:
The patent employs a dynamic measurement approach where the system measures complex dielectric permittivity at multiple frequencies and extracts moisture content dynamically. Instead of relying on fixed horn dimensions for matching, the system adapts to varying moisture levels through frequency-sweep measurements and complex permittivity analysis, maintaining reliability across the full moisture range.
4Measurement precision
If dielectric plates are used in transition horns, then impedance matching is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent completely removes dielectric plates from the measurement system. By eliminating the matching structures that required mechanical support, the invention achieves impedance matching through electrical measurement methods alone, thereby removing the mechanical weakness introduced by dielectric plates while maintaining measurement accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate, universal moisture measurements in bulk materials by accounting for complex dielectric permittivity and temperature, reducing measurement errors and mechanical stress, and allowing for in-process monitoring without sampling.
Implementation Method 1
measures the moisture content in a material based on attenuation and phase shift of the probing signal propagating through the material
Implementation Method 2
measuring the complex dielectric permittivity of the material based on the attenuation and phase shift of the probing signal
Implementation Method 3
measures the moisture content in a material based on attenuation and phase shift of the probing signal
Implementation Method 4
measures the moisture content in a material based on attenuation and phase shift of the probing signal
Data Source
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AI summary
The moisture meter for measuring the moisture content of bulk solids comprises a harmonic signal generator which is retuneable in terms of frequency and the control input of which is connected to an electronic control device, a primary transducer formed by an outer shielding conductor and a signal conductor, with the space between said conductors being filed with the material to be measured, a measuring cell which is included between the output of the generator and the input of the primary transducer, and a measuring device which is connected to the control device and the measuring cell. The outer shielding conductor of the primary transducer used is a metallic hopper. The signal conductor is in the form of a small metallic bar, which is mounted inside the hopper and is fixed in openings formed in the walls of said hopper. An insulator consisting of a dielectric is mounted in an opening at a first end of the small bar, and the small bar is connected at its second end to the wall of the hopper. The moisture meter measures the moisture content of bulk solids without taking samples, and ensures an increased level of accuracy and insensitivity to variations in the density of the material at low moisture content levels.