CN108089062A - A kind of detection method of porous media dielectric constant - Google Patents
A kind of detection method of porous media dielectric constant Download PDFInfo
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- CN108089062A CN108089062A CN201711358405.2A CN201711358405A CN108089062A CN 108089062 A CN108089062 A CN 108089062A CN 201711358405 A CN201711358405 A CN 201711358405A CN 108089062 A CN108089062 A CN 108089062A
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- dielectric constant
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2617—Measuring dielectric properties, e.g. constants
- G01R27/2623—Measuring-systems or electronic circuits
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Abstract
The present invention relates to the technical fields of dielectric constant detection, and in particular to the computational methods of porous media dielectric constant.Its step includes, and the relatively low sample of moisture content is pulverized, and the powdered samples under different quality are compacted using homemade cylindrical stainless steel measuring unit.Dielectric constant measurement is carried out to the sample after compacting using the terminal open circuit coaxial probe being connected with Network Analyzer.The relation of sample permittivity and frequency is drawn with regression analysis, sample permittivity actual measured value is fitted to obtain to the mathematical model for being suitable for porous media dielectric constant measurement under certain frequency with the dielectric mixed equation theoretical value selected in advance.
Description
Technical field
The invention belongs to the technical field of dielectric constant detection, more particularly to the detection side of porous media dielectric constant
Method.
Background technology
Dielectric constant is a kind of intrinsic physical attribute of dielectric, can represent the ability of dielectric storage electric field energy, instead
Reflect the ability that the dielectric improves condenser capacity.Dielectric constant detection method is mainly used at this stage is based on network
The dielectric and magnetic technology of analyzer, it the advantages of be that measurement is rapid, quick, and one-shot measurement can be obtained by under all frequencies
Dielectric parameter.But it is that the solid of surfacing is either uniform to measured object requirement for the accuracy for ensureing measurement
Liquid.For the porous media that porosity is larger, simple measurement using this technology can generate relatively low repetitive rate and measurement
Error.Dielectric constant theoretical value actually needs to draw by mixed equation, and sample is also required to carry out pretreatment to ensure measurement
Precisely.In terms of patent, the technology with the dielectric constant of the method detection porous media is almost blank.
The content of the invention
For existing measurement technology there are the defects of, the applicant provides the detection side of porous media dielectric constant
Method.This method can ensure the accuracy of porous media dielectric constant measurement, so as to the microwave drying process work for porous media
Skill optimization provides reference and guidance.
Technical scheme is as follows：
(1) sample pretreatment：Porous media is cut into the relatively regular sheet sample of shape.Microwave in micro-wave oven is put into do
It is dry to compared with low water content, the sample comminution of intimate over dry is filtered out into uniform and delicate into powder with sieve with medicinal pulverizer
Powder.
(2) it is compacted：Powder sample is compacted in a homemade cylindrical stainless steel measuring unit using hydraulic device,
The sample diameter for the powder final molding being compacted is respectively equal to the internal diameter and height of test cell with thickness, changes different powder
Last quality obtains the powder sample under different densities successively.Edging machine flanging is placed it in after finally paving surface.
(3) measure of density and porosity：Use quality and volume basis calculate the density of the powder sample after crushed
ρ, the density measure of primary sample use bottle method.Experiment, which is repeated five times, with water work replacement solution is averaged to obtain original porous
Media density is ρm, porosity formulaIt is calculated.
(4) under different densities example dielectric characteristic measure：Before experiment is measured, first Network Analyzer is preheated
After 30min, then relevant parameter scope is set and the end of air, short circuit fault and deionized water to Network Analyzer is respectively adopted
Coaxial high-temperature probe of opening a way is calibrated.Ensure that the measured value sensitivity of open end coaxial probe is less than 0.5.Calibration is completed
Afterwards, the cylindrical stainless steel measuring unit equipped with powder sample is assembled in the stainless steel barrel in thermostatical oil bath, operation
When ensure the sample of measuring unit and the intimate surface contact of coaxial probe to prevent the air gap.Thermostatical oil bath is used for
The temperature of control material, thermocouple insertion material monitor its temperature on-line.
(5) regression analysis is carried out to the dielectric constant in the range of different frequency and fissipation factor with related software, obtains sample
Relation between product dielectric constant, fissipation factor and frequency is as follows：
Wherein, a, b are the constant that regression analysis obtains.
(6) by original irregular sample rate ρmCorresponding a, b parameter can be acquired by bringing linear equation into, and then obtain original
The relation for irregular sample dielectric and the frequency of beginning.
(7) obtained dielectric constant is brought into related mixed equation (1), (2), (3), (4) to the relational expression of frequency,
So as to calculate the dielectric Theory value based on different mixed equations.Pass through the actual measured value for comparing sample and different mixed equations
Calculated value, determine the mixed equation that most suitable porous media dielectric calculates.
lgε2=Alg ε1 2+(1-A)lgε2 2 (1)
Ln ε=[ln (ε1)+Aln(ε2)]3 (3)
Wherein, A is the porosity of porous media.
Description of the drawings
Fig. 1 is dielectric property detection device schematic diagram (the 1- computers of the present invention；2- Network Analyzers；3- metal probes
Frame；4 coaxial cables；5- temperature sensors；6- thermometers；7- thermostatical oil baths；8- dielectric probes；9- samples)
Fig. 2 is porous media dielectric constant theoretical value and the relation of calculated value and frequency
Specific embodiment
The invention will be further described with reference to the accompanying drawings and examples.
The dielectric property detection method of porous media is comprised the following steps：
(1) sample pretreatment：Porous media is cut into the relatively regular sheet sample of shape.50g samples is taken to be put into microwave
Stove drying pulverizes to 10% or so moisture wet basis, the powder of uniform and delicate is filtered out with sieve.
(2) it is compacted：Powder sample is compacted in a homemade cylindrical stainless steel measuring unit using hydraulic device
(having different scales in stainless steel measuring unit, total unit internal diameter is 25mm, is highly 15mm), the powder being compacted finally into
The sample diameter of type is respectively equal to the internal diameter and height of test cell with thickness, changes different powder qualities and obtains 3 successively
Powder sample under kind different densities.Respectively 0.968,1.034,1.129g/cm3, pressure is placed it in after finally paving surface
20min obtains final compacting sample under the machine of side.
(3) measure of density and porosity：The density measure of primary sample uses bottle method.Made to substitute solution weight with water
Multiple five experiments be averaged original porous media particle density is 1.257 ± 0.015g/cm3, porosity passes through related public
Formula is calculated as 0.68 ± 0.05
(4) under different densities sample permittivity measure：Before experiment is measured, first Network Analyzer is preheated
After 30min, then relevant parameter scope is set and the end of air, short circuit fault and deionized water to Network Analyzer is respectively adopted
Coaxial high-temperature probe of opening a way is calibrated.Ensure that the measured value sensitivity of open end coaxial probe is less than 0.5.Calibration is completed
Afterwards, the cylindrical stainless steel measuring unit equipped with powder sample is assembled in the stainless steel barrel in thermostatical oil bath, operation
When ensure the sample of measuring unit and the intimate surface contact of coaxial probe to prevent the air gap.Thermostatical oil bath is used for
The temperature of control material, thermocouple insertion material monitor its temperature on-line.
(5) to carry out Regression Analysis Result to the dielectric constant in the range of different frequency with related software as follows；
A=113.48 ρ -92.93 R2=0.998
B=3106.81 ρ -2837.51 R2=0.980
1 porous media of table corresponding constant under different densities
(6) by original irregular porous media sample rate ρm=1.257 ± 0.015g/cm3Bringing linear equation into can ask
Corresponding a, b parameter is obtained, and then the relation for obtaining original irregular sample dielectric and frequency is as follows：
(7) bring obtained dielectric into related mixed equation (1), (2), (3), (4) to the relational expression of frequency, calculate
Dielectric Theory value based on different mixed equations.The calculated value such as attached drawing of the actual measured value of sample and different mixed equations
Shown in 2.As seen from the figure, it is equation 4 to be most suitable for the mixed equation that porous media dielectric constant calculates.
Claims (4)
1. a kind of detection method of porous media dielectric constant, it is characterised in that：It is surveyed with Network Analyzer coaxial probe technology
The dielectric constant in the range of certain frequency is determined, on this basis with regression analysis to the calculated value and reality of mixed equation
Border detected value is mutually fitted to obtain the mathematical model for being most suitable for porous media dielectric constant.
2. according to claim 1 use Network Analyzer coaxial probe technology dielectric constant, it is characterised in that：Measured is more
Hole medium is calculated by crushing and the pretreatment of compacting, pretreated rear product density ρ with quality and volume basis, original sample
The density of product draws with bottle method, porosity formulaIt is calculated.
3. it is according to claim 1 with regression analysis to the calculated value of mixed equation compared with actually detected value,
It is characterized in that：Carry out regression analysis to the dielectric constant in the range of different frequency, the sample permittivity and frequency of selection it
Between relational model it is as follows：
<mrow>
<msup>
<mi>&epsiv;</mi>
<mo>&prime;</mo>
</msup>
<mo>=</mo>
<mi>a</mi>
<mo>+</mo>
<mfrac>
<mi>b</mi>
<mi>f</mi>
</mfrac>
</mrow>
Wherein, a, b are the constant that regression analysis obtains, and f is frequency.
4. most suitable porous Jie is obtained compared with actually detected value according to the calculated value of the mixed equation in claim 1
The mathematical model of matter dielectric constant, it is characterised in that：Obtained dielectric constant is brought into related mixing to the relational expression of frequency
Equation (1), (2), (3), (4) calculate the dielectric Theory value based on different mixed equations,
lgε2=Alg ε1 2+(1-A)lgε2 2 (1)
<mrow>
<mi>&epsiv;</mi>
<mo>=</mo>
<msup>
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<mo>&lsqb;</mo>
<mi>A</mi>
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<mi>&epsiv;</mi>
<mn>1</mn>
</msub>
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</mrow>
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<mn>1</mn>
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</mrow>
Ln ε=[ln (ε1)+Aln(ε2)]3 (3)
<mrow>
<mi>&epsiv;</mi>
<mo>-</mo>
<msub>
<mi>&epsiv;</mi>
<mn>1</mn>
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</mrow>
</mrow>
Wherein, A is the porosity of porous media.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711358405.2A CN108089062A (en) | 2017-12-17 | 2017-12-17 | A kind of detection method of porous media dielectric constant |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101158702A (en) * | 2007-10-30 | 2008-04-09 | 电子科技大学 | Dielectric materials high-temperature complex dielectric constant measurement method based on terminal short circuit method |
| CN102353847A (en) * | 2011-07-08 | 2012-02-15 | 山东大学 | Method for measuring dielectric constant of underground double-layer medium and system thereof |
| CN106839751A (en) * | 2017-03-29 | 2017-06-13 | 江南大学 | A kind of microwave drying control system based on dielectric property dynamic change |
-
2017
- 2017-12-17 CN CN201711358405.2A patent/CN108089062A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101158702A (en) * | 2007-10-30 | 2008-04-09 | 电子科技大学 | Dielectric materials high-temperature complex dielectric constant measurement method based on terminal short circuit method |
| CN102353847A (en) * | 2011-07-08 | 2012-02-15 | 山东大学 | Method for measuring dielectric constant of underground double-layer medium and system thereof |
| CN106839751A (en) * | 2017-03-29 | 2017-06-13 | 江南大学 | A kind of microwave drying control system based on dielectric property dynamic change |
Non-Patent Citations (1)
| Title |
|---|
| 宋春芳等: "基于微波加热的馒头介电特性的分析与研究", 《食品与生物技术学报》 * |
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Application publication date: 20180529 |