CN111443106A - Method and system for testing equivalent thermal conductivity coefficient of heterogeneous material - Google Patents

Method and system for testing equivalent thermal conductivity coefficient of heterogeneous material Download PDF

Info

Publication number
CN111443106A
CN111443106A CN202010412999.6A CN202010412999A CN111443106A CN 111443106 A CN111443106 A CN 111443106A CN 202010412999 A CN202010412999 A CN 202010412999A CN 111443106 A CN111443106 A CN 111443106A
Authority
CN
China
Prior art keywords
temperature
thermal conductivity
sample
heat
measured
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202010412999.6A
Other languages
Chinese (zh)
Other versions
CN111443106B (en
Inventor
杜银飞
代明欣
陈嘉祺
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Central South University
Original Assignee
Central South University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Central South University filed Critical Central South University
Priority to CN202010412999.6A priority Critical patent/CN111443106B/en
Publication of CN111443106A publication Critical patent/CN111443106A/en
Application granted granted Critical
Publication of CN111443106B publication Critical patent/CN111443106B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00Investigating or analyzing materials by the use of thermal means
    • G01N25/20Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00Investigating or analyzing materials by the use of thermal means
    • G01N25/18Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)

Abstract

The invention discloses a method and a system for testing equivalent thermal conductivity of a heterogeneous material. And then establishing a one-dimensional heat transfer model in finite element software, applying a temperature field, and drawing temperature rise curves of the upper surface of the test piece under different heat conductivity coefficients. Wherein the upper and lower lines closest to the temperature rise curve obtained by actually measuring the temperature are the initial range of the equivalent thermal conductivity coefficient. And repeatedly selecting different heat conductivity coefficients in the range for simulation and comparison until the heat conductivity coefficient used in the finite element model is the equivalent heat conductivity coefficient of the sample to be measured when the temperature change curves obtained by the test and the finite element model are close or coincident. The method can not damage the sample to be tested, simplify the measurement process of the heat conductivity coefficient, reduce the requirement of test conditions, improve the accuracy of the measurement result and reduce the test cost.

Description

Method and system for testing equivalent thermal conductivity coefficient of heterogeneous material
Technical Field
The invention belongs to the technical field of heat conductivity coefficient testing, and particularly relates to a method and a system for testing equivalent heat conductivity coefficient of a heterogeneous material.
Background
Heat transfer is a phenomenon commonly existing in nature, and particularly in the industrial field, a large number of heat transfer problems need to be researched. Thermal conductivity is an important thermal property of a material, which directly reflects the heat transfer capability of the material. Current methods for measuring thermal conductivity can be broadly divided into two broad categories, namely steady state and unsteady state. In the steady state method, a sample to be measured is placed in a constant temperature field, and after the overall temperature of the sample reaches balance, the heat conductivity coefficient can be directly measured according to the measured heat flow passing through the sample in unit area, the temperature gradient of the sample in the heat conduction direction and the overall dimension of the sample. In the unsteady state method, temperature disturbance is applied to the interior or the boundary of a sample to be tested, then the change condition of the temperature of a sample testing area along with time is obtained, further the thermal diffusion coefficient of the sample to be tested is obtained, and finally the thermal conductivity coefficient of the material is obtained.
The heterogeneous material is composed of a solid framework structure and a pore structure, the distribution of the solid framework structure and the pore structure has certain variability, and particularly the pore structure can seriously influence the heat transfer. By adopting the conventional steady-state and unsteady-state measurement methods, the influence of the material space distribution cannot be effectively considered, so that the experimental test result has great deviation.
Disclosure of Invention
The invention aims to provide a method and a system for testing equivalent thermal conductivity of a heterogeneous material, which can not damage a sample to be tested and can reduce the requirement of test conditions aiming at the defects of the prior art.
The invention provides a method for testing equivalent thermal conductivity of a heterogeneous material, which comprises the following steps:
sampling, namely measuring the density and specific heat capacity of a sample, and placing the sample to be measured in a constant temperature environment for heat preservation for 4-6 h;
heating the bottom of a sample to be measured, measuring the temperature of the upper surface of the sample, and drawing a time-temperature curve;
step three, establishing a finite element heat transfer model of the sample to be measured;
selecting a heat conductivity coefficient, applying a constant temperature boundary equivalent to the constant temperature boundary in the step two to the bottom end of the model, and recording a time-temperature curve of the upper surface of the finite element heat transfer model under the heat conductivity coefficient;
step five, comparing the time-temperature curve measured by the finite element model with the actually measured time-temperature curve;
step six, if the measured time-temperature curve of the finite element model is higher than the measured time-temperature curve, the heat conductivity coefficient is reduced by 0.N, and then the step four and the step five are repeated,
if the measured time-temperature curve of the finite element model is lower than the measured time-temperature curve, adding 0.N on the basis of the heat conductivity coefficient, and repeating the fourth step and the fifth step;
step seven, repeating the step six until two adjacent heat conduction coefficients X.Y and X.Y +/-0. N are respectively positioned at the upper side and the lower side of the actual measurement time-temperature curve, and then judging that the actual heat conduction coefficient is positioned between the two heat conduction coefficients;
step eight, if accurate calculation is not needed, judging the common position X of the two heat conduction coefficients as an actual heat conduction coefficient;
step nine, if accurate calculation is needed, selecting the gradient value of the thermal conductivity coefficient to be 0.0N, repeating the step six to the step eight between X.Y and X.Y +/-0. N, and determining the thermal conductivity coefficient X.Y;
step ten, repeating the step nine to determine the thermal conductivity coefficients X.YZ, X.YZZ, … and X.YZ … Z; and if the time-temperature curve corresponding to the thermal conductivity selected in the comparison process is coincident with the time-temperature curve measured by the test, the thermal conductivity is the corresponding equivalent thermal conductivity.
The sample to be detected is a sample with flat upper and lower bottom surfaces, and has no shape requirement; the sample to be tested is surrounded by a heat insulating layer.
Preferably, the heat insulating layer is a heat insulating foam material.
Preferably, the temperature for heat preservation in the first step is between 20 and 30 DEG C
Preferably, the heating in the second step is constant temperature heating, and the heating temperature is between 50 and 60 ℃.
The invention also provides a system for testing equivalent thermal conductivity of the heterogeneous material, which is used for heating and measuring the temperature of the sample to be tested.
The system comprises a constant temperature heating device and a temperature measuring device; the temperature measuring device is used for measuring the temperature of a sample to be measured in the heat insulation layer.
Preferably, the constant-temperature heating device is a stainless steel constant-temperature heating plate capable of keeping the surface temperature of the device constant, and the temperature control range is 20-100 ℃.
In order to ensure the heating effect, the sample to be measured is provided with a flat base surface which can be in close contact with the constant-temperature heating device.
In one embodiment, the temperature measuring device is an infrared thermal imager.
The invention compares the time temperature curve obtained by finite element software simulation with the time temperature curve obtained by actual measurement, finds out the interval range of the equivalent heat conductivity coefficient by a plurality of comparisons, and repeatedly selects different heat conductivity coefficients in the range for simulation comparison until the heat conductivity coefficient used in the finite element model is the equivalent heat conductivity coefficient of the sample to be measured when the test is similar to or coincident with the temperature change curve obtained by the finite element model. In the whole use, a constant-temperature heat source is provided through the constant-temperature heating device, the test requirement is simple, the average temperature data of the surface of the sample is obtained by adopting the infrared thermal imager, the complex sensor connection is not needed, and the data acquisition is convenient. And finally, establishing a heat transfer model through finite element software, and comparing the change relation of the temperature along with time to obtain the equivalent heat conductivity coefficient of the heterogeneous material. The method has the advantages of not damaging the sample to be tested, simplifying the measurement process of the thermal conductivity, reducing the requirement of test conditions, improving the accuracy of the measurement result of the thermal conductivity of the heterogeneous material and reducing the test cost.
Drawings
Fig. 1 is a schematic view of a preferred embodiment of the present invention in use.
FIG. 2 is a schematic diagram of a finite element simulation of the preferred embodiment.
Fig. 3 is a process block diagram of the preferred embodiment.
Sequence numbers of the drawings:
1-a sample to be tested; 2-constant temperature heating device; 3, heat insulating layer; 4-temperature measuring device.
Detailed Description
As shown in fig. 1, the system for testing equivalent thermal conductivity of heterogeneous material disclosed in this embodiment is used to heat and measure the temperature of a sample 1 to be tested. The sample 1 to be measured has a flat base surface so as to be able to be brought into close contact with the constant-temperature heating apparatus, and the sample 1 to be measured is selected to be a cylinder in this embodiment.
The test system comprises a constant temperature heating device 2, a heat insulation layer 3 and a temperature measuring device 4, wherein the constant temperature heating device 2 is a stainless steel constant temperature heating plate (model DB-3AB) capable of keeping the surface temperature of the device constant, the temperature control range is 20-100 ℃, the heat insulation layer 3 is made of heat insulation foam materials and is adhered to the outside of a sample 1 to be tested, then the sample to be tested coated with the heat insulation layer 3 is placed on the stainless steel constant temperature heating plate, and then the surface temperature of the sample to be tested is measured through the temperature measuring device 4 (model F L IR).
Selecting a cylinder with the diameter of 10cm and the height of 10cm as a sample to be tested, and testing the density and the specific heat capacity of the sample to be tested to obtain the density of 2.12g/cm3The specific heat capacity is 734J/(kg. cndot.). The ambient temperature was 25 ℃ and the heating device temperature was set to 50 ℃. The initial temperature of the surface of the sample to be measured was measured using a temperature measuring device, and then the surface temperature of the sample to be measured was measured every 15 minutes. The time and temperature table is shown in Table 1
Figure BDA0002493998980000041
A finite element heat transfer model was created using ABAQUS software based on measured test parameters as shown in figure 2,
assuming that the density and specific heat capacity of the sample to be tested do not change with time, the transient heat balance can be expressed by a matrix:
Figure BDA0002493998980000042
wherein [ C ]]Is a matrix of specific heat, and is,
Figure BDA0002493998980000043
is a derivative matrix of the node temperature with respect to time, [ K]Is a heat conduction matrix, [ T ]]Is a node temperature matrix, [ Q ]]Is a node heat flow rate matrix.
Selecting a heat conductivity coefficient of 1.10W/(m.K), applying equivalent thermal load to the bottom end of the model, and recording a time-temperature curve of the surface of the finite element heat transfer model under the heat conductivity coefficient; then comparing the value with the measured value, if the value is smaller than the measured value, increasing the value by 0.02W/(m.K) on the basis of the thermal conductivity coefficient of 1.10W/(m.K), namely selecting the thermal conductivity coefficient of 1.12W/(m.K), repeating the simulation to obtain another set of time-temperature data, obtaining the change situation of the upper surface temperature of the sample to be measured under different thermal conductivity coefficients, recording the change situation in the table 1, and repeating the steps until the simulated value is larger than the measured value.
And (4) drawing temperature rise curves under different heat conductivity coefficients and a temperature rise curve obtained by actually measuring the temperature. Wherein the upper and lower lines closest to the temperature rise curve obtained by actually measured temperature are in the range of equivalent thermal conductivity coefficient.
The actual thermal conductivity is found to be between 1.12W/(mK) and 1.14W/(mK). If the requirement on the accuracy of the equivalent thermal conductivity is not high, the equivalent thermal conductivity is 1.1W/(m.K). If higher, the test can be repeated within the interval of 1.12-1.14W/(m.K).
In order to verify the test result, a thermal conductivity tester (the model is DRE-2C) based on the transient flat plate heat source method is adopted to measure the sample to be tested for many times, the average thermal conductivity is 1.12W/(m.K), and the difference between the test data obtained by the test method is not great, which indicates that the test result of the method is accurate.

Claims (10)

1. A method for testing equivalent thermal conductivity of a heterogeneous material is characterized by comprising the following steps:
sampling, namely measuring the density and specific heat capacity of a sample, and placing the sample to be measured in a constant temperature environment for heat preservation for 4-6 h;
heating the bottom of a sample to be measured, measuring the temperature of the upper surface of the sample, and drawing a time-temperature curve;
step three, establishing a finite element heat transfer model of the sample to be measured;
selecting a heat conductivity coefficient, applying a constant temperature boundary equivalent to the constant temperature boundary in the step two to the bottom end of the model, and recording a time-temperature curve of the upper surface of the finite element heat transfer model under the heat conductivity coefficient;
step five, comparing the time-temperature curve measured by the finite element model with the actually measured time-temperature curve;
step six, if the measured time-temperature curve of the finite element model is higher than the measured time-temperature curve, the heat conductivity coefficient is reduced by 0.N, and then the step four and the step five are repeated,
if the measured time-temperature curve of the finite element model is lower than the measured time-temperature curve, adding 0.N on the basis of the heat conductivity coefficient, and repeating the fourth step and the fifth step;
step seven, repeating the step six until two adjacent heat conduction coefficients X.Y and X.Y +/-0. N are respectively positioned at the upper side and the lower side of the actual measurement time-temperature curve, and then judging that the actual heat conduction coefficient is positioned between the two heat conduction coefficients;
step eight, if accurate calculation is not needed, judging the common position X of the two heat conduction coefficients as an actual heat conduction coefficient;
step nine, if accurate calculation is needed, selecting the gradient value of the thermal conductivity coefficient to be 0.0N, repeating the step six to the step eight between X.Y and X.Y +/-0. N, and determining the thermal conductivity coefficient X.Y;
step ten, repeating the step nine to determine the thermal conductivity coefficients X.YZ, X.YZZ, … and X.YZ … Z; and if the time-temperature curve corresponding to the thermal conductivity selected in the comparison process is coincident with the time-temperature curve measured by the test, the thermal conductivity is the corresponding equivalent thermal conductivity.
2. The method for testing equivalent thermal conductivity of a heterogeneous material of claim 1, wherein: the sample to be detected is a sample with flat upper and lower bottom surfaces, and has no shape requirement; the sample to be tested is surrounded by a heat insulating layer.
3. The method for testing equivalent thermal conductivity of a heterogeneous material of claim 2, wherein: the heat insulation layer is made of heat insulation foam material.
4. The method for testing equivalent thermal conductivity of a heterogeneous material of claim 1, wherein: the temperature of the first step is 20-30 ℃.
5. The method for testing equivalent thermal conductivity of a heterogeneous material of claim 1, wherein: and in the second step, constant-temperature heating is adopted, and the heating temperature is 50-60 ℃.
6. A system for testing equivalent thermal conductivity of a heterogeneous material, the system being adapted to heat and measure the temperature of a sample according to claim 1.
7. The heterogeneous material equivalent thermal conductivity test system of claim 6, wherein: the system comprises a constant temperature heating device and a temperature measuring device; the temperature measuring device is used for measuring the temperature of a sample to be measured in the heat insulation layer.
8. The heterogeneous material equivalent thermal conductivity test system of claim 7, wherein: the constant temperature heating device is a stainless steel constant temperature heating plate capable of keeping the surface temperature of the device constant, and the temperature control range is 20-100 ℃.
9. The heterogeneous material equivalent thermal conductivity test system of claim 8, wherein: the sample to be measured is provided with a flat base surface which can be in close contact with the constant-temperature heating device.
10. The heterogeneous material equivalent thermal conductivity test system of claim 7, wherein: the temperature measuring device is an infrared thermal imager.
CN202010412999.6A 2020-05-15 2020-05-15 Method and system for testing equivalent thermal conductivity coefficient of heterogeneous material Active CN111443106B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010412999.6A CN111443106B (en) 2020-05-15 2020-05-15 Method and system for testing equivalent thermal conductivity coefficient of heterogeneous material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010412999.6A CN111443106B (en) 2020-05-15 2020-05-15 Method and system for testing equivalent thermal conductivity coefficient of heterogeneous material

Publications (2)

Publication Number Publication Date
CN111443106A true CN111443106A (en) 2020-07-24
CN111443106B CN111443106B (en) 2023-02-21

Family

ID=71655173

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010412999.6A Active CN111443106B (en) 2020-05-15 2020-05-15 Method and system for testing equivalent thermal conductivity coefficient of heterogeneous material

Country Status (1)

Country Link
CN (1) CN111443106B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114858849A (en) * 2022-07-11 2022-08-05 中国空气动力研究与发展中心低速空气动力研究所 Method for obtaining thermal conductivity coefficient of dynamic ice
CN116757007A (en) * 2023-08-23 2023-09-15 中南大学 Method for predicting influence of low-temperature phase-change material on temperature and ice condensation of asphalt pavement

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011106918A (en) * 2009-11-16 2011-06-02 Stanley Electric Co Ltd Method and system for calculating heat conductivity
CN104280419A (en) * 2013-07-01 2015-01-14 北京中建建筑科学研究院有限公司 Method for testing material heat conductivity coefficient through transient plane heat source method
CN106093115A (en) * 2016-08-25 2016-11-09 青岛励赫化工科技有限公司 A kind of rubber heat conductivity accuracy tester
CN106248725A (en) * 2016-09-16 2016-12-21 北京工业大学 A kind of porous media Equivalent Thermal Conductivities measuring method
CN109001250A (en) * 2018-06-26 2018-12-14 中国电子科技集团公司第五十五研究所 Thermal conductivity of thin film analysis method based on infrared thermography

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011106918A (en) * 2009-11-16 2011-06-02 Stanley Electric Co Ltd Method and system for calculating heat conductivity
CN104280419A (en) * 2013-07-01 2015-01-14 北京中建建筑科学研究院有限公司 Method for testing material heat conductivity coefficient through transient plane heat source method
CN106093115A (en) * 2016-08-25 2016-11-09 青岛励赫化工科技有限公司 A kind of rubber heat conductivity accuracy tester
CN106248725A (en) * 2016-09-16 2016-12-21 北京工业大学 A kind of porous media Equivalent Thermal Conductivities measuring method
CN109001250A (en) * 2018-06-26 2018-12-14 中国电子科技集团公司第五十五研究所 Thermal conductivity of thin film analysis method based on infrared thermography

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
LANG LU 等: "Modeling and Simulation of Local Thermal Non-equilibrium Effects in Porous Media with Small Thermal Conductivity", 《TRANSP POROUS MED》 *
徐松杰: "纳米气凝胶改性水泥基材料耐高温性能试验研究及其应用", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 *
郭茶秀 等: "泡沫型多孔介质等效导热系数研究进展", 《储能科学与技术》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114858849A (en) * 2022-07-11 2022-08-05 中国空气动力研究与发展中心低速空气动力研究所 Method for obtaining thermal conductivity coefficient of dynamic ice
CN116757007A (en) * 2023-08-23 2023-09-15 中南大学 Method for predicting influence of low-temperature phase-change material on temperature and ice condensation of asphalt pavement
CN116757007B (en) * 2023-08-23 2023-11-03 中南大学 Method for predicting influence of low-temperature phase-change material on temperature and ice condensation of asphalt pavement

Also Published As

Publication number Publication date
CN111443106B (en) 2023-02-21

Similar Documents

Publication Publication Date Title
CN111443106B (en) Method and system for testing equivalent thermal conductivity coefficient of heterogeneous material
US4840495A (en) Method and apparatus for measuring the thermal resistance of an element such as large scale integrated circuit assemblies
CN104535609A (en) Device for determining heat-conductivity coefficient
CN109752113B (en) Sheet temperature sensor, position determining method and circuit design method in application of sheet temperature sensor
CN105415312A (en) Circuit board clamping table and temperature measurement system
CN110927212B (en) Testing device for thermal conductivity coefficient and contact thermal resistance of gas diffusion layer in laminated state
CN103837834A (en) Testing method of thermal runaway characteristic of battery
CN207675681U (en) A kind of materials for wall thermal conductivity measuring apparatus
CN109324079B (en) Material thermal expansion coefficient measuring method based on ultrasound
CN110779954A (en) Device and method for measuring contact heat conductivity coefficient in plastic deformation state
CN108490024A (en) A method of the heterogeneous content of limited thickness material is measured based on fictitious heat source principle
CN112858381B (en) Heat insulation performance test device and test method for heat insulation material for high-speed aircraft engine
CN103983660A (en) Indoor rock sample heat conduction coefficient testing device
CN104020188A (en) Unfavorable conductor heat conduction coefficient measuring device and unfavorable conductor heat condution coefficient measuring method
CN116718633A (en) Intelligent detection system and method for soft measurement of heat insulation performance of heat insulation material
CN106053527B (en) Method that is a kind of while testing power battery anisotropy thermal diffusion coefficient
CN111474204B (en) Method for testing heat conductivity coefficient of cylindrical sample by punching method
CN115616030B (en) Measurement method of heat conductivity coefficient
CN219162032U (en) Test fixture
CN106546628A (en) A kind of lossless detection method based on temperature field tomography
CN111610216A (en) Freezing and thawing environment moisture migration testing equipment
Rabin et al. Infrared temperature sensing of mechanically loaded specimens: thermal analysis
CN102128855B (en) Device and method for measuring high temperature thermophysical property
CN110887862A (en) Rapid heat-conducting performance testing device and testing method thereof
CN112034001A (en) System and method for measuring thermophysical property parameters of solid material based on multi-dimensional plane heat source method

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant