CN113484362A - Method for correcting heat transfer area of heat conductivity coefficient tester - Google Patents
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Abstract
The invention discloses a method for correcting heat transfer area by a heat conductivity coefficient tester, wherein the heat conductivity coefficient tester comprises a metering hot plate and a protective hot plate, and a gap is arranged between the metering hot plate and the protective hot plate, and the method comprises the following steps: s1, obtaining a function curve of the position of the lowest temperature point at the gap along with the change of the temperature difference between the metering hot plate and the protective hot plate in a mathematical modeling mode; s2, measuring actual temperature deviation through experiments; s3, substituting the obtained actual temperature deviation into the function curve of the step S1 to obtain the actual position of the temperature lowest point at the gap; and S4, acquiring the effective radius of the metering hot plate based on the actual position of the temperature lowest point, and calibrating the heat transfer area by using the effective radius of the metering hot plate. The invention has the advantage that the heat transfer area is corrected according to the position of the lowest temperature point at the gap, thereby reducing the measurement error of the heat conductivity coefficient caused by inaccurate heat transfer area.
Description
Technical Field
The invention relates to the technical field of measurement of heat conductivity of materials, in particular to a method for correcting a heat transfer area by a heat conductivity coefficient tester.
Background
The thermal conductivity is defined as the heat flow per unit temperature gradient perpendicular to the unit direction passing through the unit area under the steady state condition, is an important parameter for evaluating the thermal conductivity of the material, and directly reflects the quality of the thermal insulation performance of the material. The thermal conductivity coefficient measuring method comprises a steady state method and a dynamic method, which have strict requirements on the type and the shape of the material, wherein the hot shield plate method belongs to the steady state method, and the measuring precision is highest; the hot plate shielding method is based on the temperature compensation principle of a metering hot plate, and measures the heat conductivity coefficient of a solid material by measuring parameters such as one-dimensional heat flow in the thickness direction of a sample, temperature gradient and the like.
Among the prior art, the protection hot plate sets up in the outside of measurement hot plate along measurement hot plate circumference, and the protection hot plate is used for preventing that the heat of measurement hot plate scatters and disappears, can leave the crack between measurement hot plate and the protection hot plate generally for reduce the heat transfer between measurement hot plate and the protection hot plate. In practical application, the thinner the metering hot plate is, the larger the gap is, the smaller the heat transfer between the metering hot plate and the protective hot plate is, and the more accurate the test is; when the measurement hot plate needs to be provided with a large area, the larger the area is, but the smaller the thickness is, the mechanical strength cannot be ensured, and the deformation is easy to occur. In addition, the larger the gap, the greater the proportion of the gap area to the area of the metering heat plate, which can cause additional measurement errors.
Therefore, when there is a temperature deviation between the measurement hot plate and the protection hot plate, an error is often generated in the measurement of the thermal conductivity meter due to an inaccurate heat transfer area.
Disclosure of Invention
The invention aims to solve the problems and provide a method for correcting the heat transfer area of a heat conductivity coefficient measuring instrument.
The technical scheme provided by the invention is a method for correcting heat transfer area by a heat conductivity tester, wherein the heat conductivity tester comprises a metering hot plate and a protective hot plate, and a gap is arranged between the metering hot plate and the protective hot plate, and the method comprises the following steps:
s1, obtaining a function curve of the position of the lowest temperature point at the gap along with the change of the temperature difference between the metering hot plate and the protective hot plate in a mathematical modeling mode;
s2, measuring the actual temperature deviation of the metering hot plate and the protective hot plate through experiments;
s3, substituting the actual temperature deviation obtained in the step S2 into the function curve of the step S1 to obtain the actual position of the temperature lowest point at the gap;
and S4, acquiring the effective radius of the metering hot plate based on the actual position of the temperature lowest point, and calibrating the heat transfer area by using the effective radius of the metering hot plate.
By the technical scheme, in order to ensure that the heat emitted by the metering hot plate completely passes through the measured sample to reach a one-dimensional stable state, the loss of the heat on the metering hot plate in various heat transfer modes can be reduced only when the temperature of the protective hot plate is required to be consistent with that of the metering hot plate; when temperature deviation exists between the metering hot plate and the protective hot plate, the heat transfer area is corrected according to the position of the lowest temperature point at the gap, and therefore heat conductivity coefficient measurement errors caused by inaccurate heat transfer area are reduced.
Further, in step S1, the specific steps are as follows:
establishing a numerical model according to boundary conditions of the metering hot plate and the protective hot plate for simulation calculation so as to obtain a temperature difference value of the metering hot plate and the protective hot plate;
analyzing a temperature field diagram of the temperature difference between the measuring hot plate and the protective hot plate to determine the position of the lowest temperature point at the gap between the measuring hot plate and the protective hot plate;
acquiring temperature difference values of a plurality of groups of metering hot plates and protective hot plates according to the step a; correspondingly, acquiring the positions of the lowest temperature points of the gaps of the plurality of groups of measuring hot plates and the protective hot plates according to the step b;
expressing the position of the temperature lowest point at the gap and the temperature difference value in a point value form; and then, fitting the obtained point values of the groups into a function curve to obtain a function relation of the position of the temperature lowest point at the gap position along with the change of the temperature difference.
According to the technical scheme, a three-dimensional model is established for analog calculation according to boundary conditions given by a metering hot plate and a protective hot plate, a calculated temperature value and a power value of the temperature value are selected as references, and the power value is changed through experiments to obtain a temperature difference value; determining the position of the lowest temperature point at the gap according to a temperature field diagram formed by the obtained temperature difference; based on a plurality of groups of values obtained by the method, obtaining a functional relation between the position of the temperature lowest point at the gap and the temperature difference value, and further obtaining a functional relation between the actual temperature difference value and the position of the temperature lowest point at the gap during an experiment;
further, in step S3, the actual position of the lowest point of temperature at the gap is obtained as follows;
Further, in the step a, a boundary condition of the temperature is selected, a temperature value is selected from the obtained temperature set as a temperature fixed value used by the metering hot plate and the protective hot plate at the same time, and the corresponding power is adjusted to float up and down to obtain different temperature difference values corresponding to different powers.
Further, in step S4, the calculation formula of the obtained calibrated heat transfer area is as follows:
wherein,
for the purpose of the calibrated heat transfer area,
in order to gauge the original area of the hot plate,
in order to gauge the original radius of the hot plate,
to measure the effective radius of the hot plate (1).
Preferably, when the gap is an unsteady gap, in step S1, a simulation calculation is performed using the geometric structure of the unsteady gap as a numerical model, so as to calibrate the heat transfer area of the unsteady gap.
Through the technical scheme, aiming at the unsteady gap, the geometric structure of the unsteady gap is adopted for simulation calculation when a numerical model is established, and the heat transfer area of the unsteady gap can be calibrated by the same other steps.
Preferably, when the gap is a line contact, in step S1, a simulation calculation is performed using the geometry of the line contact as a numerical model, and the heat transfer area of the line contact is calibrated.
Through the technical scheme, aiming at the line contact, the geometric structure of the line contact is adopted for simulation calculation when the numerical model is established, and the heat transfer area of the line contact can be calibrated by the same other steps.
Furthermore, the number of the metering hot plates and the number of the protective hot plates are two, and the heating elements are arranged between the two metering hot plates and the two protective hot plates.
Further, the heating member is a heating wire or a film heating sheet.
Further, the thermal conductivity tester also comprises two cold plates, two spaces are respectively formed between the two cold plates and the two metering hot plates, and the spaces are used for placing samples.
Further, in step S4, the samples are placed in the spaces, respectively.
The invention has the beneficial effects that: in order to ensure that the heat emitted by the metering hot plate completely passes through a measured sample to reach a one-dimensional stable state, the invention requires that the temperature of the protective hot plate is consistent with that of the metering hot plate, so that the heat on the metering hot plate can be reduced to be dissipated in various heat transfer modes; when temperature deviation exists between the metering hot plate and the protective hot plate, the heat transfer area is corrected according to the position of the lowest temperature point at the gap, and therefore heat conductivity coefficient measurement errors caused by inaccurate heat transfer area are reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic structural view of a protective heat plate of a heating unit of a thermal conductivity meter according to an embodiment of the present invention, where the protective heat plate is provided with a first protrusion;
fig. 2 is a schematic structural diagram of a protective hot plate and a metering hot plate of a heating unit of a thermal conductivity meter according to an embodiment of the present invention, both of which are provided with first protrusions;
fig. 3 is a schematic structural diagram of a heating unit of a thermal conductivity meter according to an embodiment of the present invention, in which a first protrusion is a trapezoid;
FIG. 4 is a schematic view of a second slit in a heating unit embodying the thermal conductivity meter of the present invention;
FIG. 5 is a schematic view of a sample and a cold plate in a heating unit embodying a thermal conductivity meter of the present invention;
FIG. 6 is a schematic view of a triangular first protrusion of a heating unit embodying the thermal conductivity meter of the present invention;
FIG. 7 is another schematic view of a triangular first protrusion of a heating unit embodying the thermal conductivity meter according to the present invention;
FIG. 8 is another schematic view of a heating unit embodying the thermal conductivity meter of the present invention in which the first protrusions are rectangular;
FIG. 9 is a further schematic view of a first protrusion of a heating unit embodying the thermal conductivity meter of the present invention;
FIG. 10 is a graph showing the lowest point of the temperature at the gap between the metering hot plate and the protective hot plate when the temperature difference is-0.2 according to the present invention;
FIG. 11 is a diagram illustrating the position of the lowest point of the temperature at the gap between the heat metering plate and the heat shielding plate when the temperature difference is 0 according to the present invention;
FIG. 12 shows the lowest point of the temperature at the gap between the heat metering plate and the heat shield plate when the temperature difference is 0.2 according to the present invention.
Reference numerals:
1-metering hot plate, 2-protective hot plate, 3-heating element, 4-first gap, 5-second gap, 6-sample, 7-cold plate,
11-first projections, 12-second projections.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The present invention will be further explained with reference to specific embodiments.
A heat conductivity coefficient measuring instrument revises the method of the heat transfer area, the heat conductivity coefficient measuring instrument includes measuring the hot plate 1 and protecting the hot plate 2, in order to guarantee that the heat that the measuring hot plate 1 sends out is all through measuring the sample 6 and reaching the one-dimensional steady state, it requires the temperature of the protecting the hot plate 2 to be identical with temperature of the measuring hot plate 1, can reduce the heat on the measuring hot plate 1 and dispel and conduct in various heat transfer ways; as shown in fig. 1 and 5, a gap is arranged between the metering heat plate 1 and the protective heat plate 2, and the gap comprises a first gap 4 and a second gap 5; the specific calibration method comprises the following steps:
s1, creating a numerical model;
establishing a numerical model according to boundary conditions of the metering hot plate 1 and the protective hot plate 2 for simulation calculation so as to obtain a temperature difference value of the metering hot plate 1 and the protective hot plate 2;
the specific implementation process is as follows:
selecting boundary conditions of a metering hot plate 1 and a protective hot plate 2 based on a specific thermal conductivity tester to create a three-dimensional model, selecting the boundary conditions of temperature, and performing numerical simulation calculation according to the formed three-dimensional model to obtain numerical values of temperature and power; selecting a temperature value from the obtained temperature set as a temperature constant value used by the metering hot plate 1 and the protective hot plate 2 at the same time, and adjusting the corresponding power to float up and down to obtain different temperature difference values corresponding to different powers;
the specific embodiment is as follows:
the radius of a measuring hot plate 1 is given to be 150mm, and the gap between the measuring hot plate 1 and a protective hot plate 2 is given to be 1 mm; the corresponding temperature differences are as follows:
s2, determining the position of the lowest temperature point at the gap between the measuring hot plate 1 and the protective hot plate 2;
analyzing a temperature field diagram of the obtained temperature difference between the measuring hot plate 1 and the protective hot plate 2 to determine the position of the lowest temperature point at the gap between the measuring hot plate 1 and the protective hot plate 2;
the specific embodiment is as follows:
based on the above technical solution, as shown in fig. 11, when the temperature difference is 0, the position of the lowest temperature point at the gap between the corresponding measurement hot plate 1 and the corresponding protective hot plate 2 is represented by a dotted line; as shown in fig. 10, when the temperature difference is-0.2, the position of the lowest temperature point at the gap between the corresponding metering hot plate 1 and the corresponding protective hot plate 2 is shifted to the left; as shown in fig. 12, when the temperature difference is 0.2, the position of the lowest temperature point at the gap between the corresponding metering hot plate 1 and the corresponding protective hot plate 2 is shifted to the right; similarly, when the temperature difference is 0.1 and-0.1, the positions of the lowest temperature points at the gaps of the metering hot plate 1 and the protective hot plate 2 are obtained; the specific results are as follows:
s3, fitting the step S1 and the step S2 into a functional relation;
obtaining temperature difference values of a plurality of groups of measuring hot plates 1 and protective hot plates 2 according to the step S1; correspondingly, the positions of the lowest temperature points of the gaps of the plurality of groups of measuring hot plates 1 and the heat shield hot plates 2 are obtained according to the step S2;
expressing the position of the temperature lowest point at the gap and the temperature difference value in a point value form; then, fitting the obtained point values of the groups into a function curve to obtain a function relation of the position of the temperature lowest point at the gap position along with the change of the temperature difference value;
based on the above technical solution, a person skilled in the art can obtain the above functional relationship fitted according to the temperature deviation and the temperature lowest point position according to the conventional basic knowledge, and the specific formula is as follows:
wherein,
for measuring the effective radius of the hot plate 1;
to measure the difference between the temperatures of the hot plate 1 and the hot shield plate 2.
S4, substituting the temperature deviation of the measuring hot plate 1 and the protective hot plate 2 measured in the experiment into the functional relation of the step S3 to obtain the effective radius of the measuring hot plate 1;
the specific implementation process is as follows:
when in experiment, the measurement hot plate 1 and the protective hot plate 2 are measured in real time to obtain the temperature difference value between the measurement hot plate 1 and the protective hot plate 2, and the temperature difference value is substituted into the function formula to obtain the corrected effective radius of the measurement hot plate 1;
s5, the effective radius of the metering hot plate 1 obtained in the step S4 is used for calibrating the heat transfer area.
The specific implementation process is as follows:
based on the technical scheme, the corrected heat transfer area is obtained according to the heat transfer area calculation formula as follows:
on the basis of the above scheme, in step S3, the functional relationship is as follows:
wherein,
for measuring the effective radius of the hot plate 1;
to measure the difference between the temperatures of the hot plate 1 and the hot shield plate 2.
On the basis of the above scheme, in step S5, the calculation formula of the calibrated heat transfer area is as follows:
wherein,
for the purpose of the calibrated heat transfer area,
in order to gauge the original area of the hot plate 1,
to gauge the original radius of the hot plate 1;
to gauge the effective radius of the hot plate 1.
Comparative examples
On the basis of the above scheme, the corrected area is compared with the uncorrected area (the uncorrected area adopts two algorithms, namely, the area of the metering hot plate 1, namely the circle with the radius of 150mm, and the area enclosed by the middle of the gap, namely the circle with the radius of 151 mm):
based on the above solution, when the gap is an unsteady gap, in step S1, a simulation calculation is performed using the geometric structure of the unsteady gap as a numerical model, and the heat transfer area of the unsteady gap is calibrated.
In addition to the above, when the parting line is in line contact, in step S1, simulation calculation is performed using the geometry of the line contact as a numerical model, and the heat transfer area of the line contact is calibrated.
On the basis of the scheme, the number of the metering hot plates 1 and the number of the protective hot plates 2 are two, and the heating elements 3 are arranged between the two metering hot plates 1 and the two protective hot plates 2.
On the basis of the scheme, the heating element 3 is a heating wire or a film heating sheet.
On the basis of the scheme, the thermal conductivity tester adopts a double-sample thermal conductivity tester, and the thermal conductivity tester also comprises two cold plates 7, two spaces are respectively formed between the two cold plates 7 and the two metering hot plates 1, and the spaces are used for placing samples 6.
As shown in fig. 1 to 5, the heating unit of the thermal conductivity meter provided in this embodiment of the present invention includes: the device comprises a metering hot plate 11, a protective hot plate 2 and a heating element 3, wherein the protective hot plate 2 is arranged on the outer side of the metering hot plate 1 along the circumferential direction of the metering hot plate 1, and the heating element 3 is respectively attached to the metering hot plate 1 and the protective hot plate 2; its characterized in that, the heating element of thermal conductivity apparatus still includes: the first protrusion 11 is arranged on the metering hot plate 1 and/or the protective hot plate 2, so that a first gap 4 is formed between the metering hot plate 1 and the protective hot plate 2, and the width of the first gap 4 is increased from the direction far away from the heating element 3 to the direction close to the heating element 3.
Specifically, the first gap 4 is a relatively uniform gap, and has a small width near the sample 6 and a large width near the heating member 3, and the increased width can reduce the heat transfer from the metering hot plate 1 to the shield hot plate 2.
Set up first arch 11 and can satisfy the intensity of measurement hot plate 1, can guarantee the thickness of measurement hot plate 1 and the size in clearance simultaneously, the area in clearance accounts for the area of measurement hot plate 1 less simultaneously, can not arouse extra measuring error.
In some embodiments of the present invention, the first protrusion 11 extends in a direction approaching the thermal shield 2 when the thermal shield 1 is provided, and the first protrusion 11 extends in a direction approaching the thermal shield 1 when the thermal shield 2 is provided.
Specifically, as shown in fig. 2, when the first protrusion 11 is provided on the metering hot plate 1, the first protrusion 11 extends in the right direction, and when the first protrusion 11 is provided on the protective hot plate 2, the first protrusion 11 extends in the left direction.
As shown in fig. 6-9, in some embodiments of the invention, the first protrusions 11 are triangular, trapezoidal, or rectangular in shape.
As shown in fig. 2, the shape of the first protrusion 11 is rectangular, as shown in fig. 3, the shape of the first protrusion 11 is trapezoidal, as shown in fig. 6 and 7, the shape of the first protrusion 11 is triangular, as shown in fig. 8, the first protrusion 11 is rectangular, the rectangular first protrusion 11 and the heat shield plate are in arc transition connection, as shown in fig. 9, another shape of the first protrusion 11 is provided, as long as the first protrusion 11 extends toward the left, which all belong to the protection scope of the present application.
In some embodiments of the present invention, the heating unit of the thermal conductivity meter further includes a second protrusion 12, the second protrusion 12 is disposed on the measuring hot plate 1 and/or the protective hot plate 2, such that a second gap 5 is formed between the measuring hot plate 1 and the protective hot plate 2, and a width of the second gap 5 increases and then decreases from a direction away from the heating member 3 to a direction close to the heating member 3.
Specifically, as shown in fig. 4, the width of the second gap 5 is smaller at the portion close to the sample 6, smaller at the portion close to the heating member 3, and larger at the middle portion, which can better increase the strength of the metering hot plate 1, and the area of the gap occupies smaller area of the metering hot plate 1, and does not cause additional measurement error.
In some embodiments of the present invention, the second protrusion 12 extends in a direction close to the thermal shield 2 when the second protrusion is provided on the thermal shield 1, and the second protrusion 12 extends in a direction close to the thermal shield 1 when the second protrusion is provided on the thermal shield 2.
Specifically, as shown in fig. 4, when the second projection 12 is provided on the measurement hot plate 1, the second projection extends in the right direction, and when the second projection 12 is provided on the shield hot plate 2, the second projection 12 extends in the left direction.
In some embodiments of the invention, the second protrusions 12 are triangular, trapezoidal or rectangular in shape.
In some embodiments of the invention, the heating unit of the thermal conductivity meter further comprises a cold plate 7, and a space is formed between the metering hot plate 1 and the cold plate 7, and the space is used for placing the sample 6.
Specifically, the thermal conductivity of the sample 6 is measured by transferring heat from the metering hot plate 1 through the sample 6 to the cold plate 7.
In some embodiments of the present invention, the number of the metering hotplate 1 and the hotplate 2 is two, and the heating element 3 is arranged between the two metering hotplates 1 and the two hotplates 2.
In particular, two samples 6 may be provided, each sample 6 being connected to a metering hotplate 1.
In some embodiments of the invention, the number of cold plates 7 is two, two spaces being formed between two cold plates 7 and two metering hot plates 1, respectively.
Specifically, two spaces are used for placing two samples 6, respectively.
In some embodiments of the present invention, the heating member 3 is a heating wire or a thin film heating sheet.
When the heating unit of the thermal conductivity tester provided by the invention is used for measuring, the uneven first gap 4 or second gap 5 can effectively reduce the measurement error of the thermal conductivity caused by the heat transfer between the temperatures of the metering hot plate 1 and the protective hot plate 2. Taking the radius of the measuring hot plate 1 as 150mm, the thickness as 20mm and the size of the sample 6 as 300 x 300 as an example, in the traditional structure, the height of the uniform gap is 1mm, and when the temperature difference between the measuring hot plate and the protective hot plate is 0.1 ℃, the heat transfer is about 0.02W, which causes the measurement error of the thermal conductivity coefficient to be about 2%. With a non-uniform first gap 4, the smaller height h1 is 1mm and the larger height h2 is 5mm, the heat transfer is 47% of a 1mm uniform gap when the larger height to smaller height ratio is 1:1, 36% when the larger height to smaller height ratio is 2:1, and only 25% when 9: 1.
In summary, in the heating unit of the thermal conductivity measuring instrument provided by the present invention, the first protrusion 11 is disposed to form the first gap 4 between the measuring hot plate 1 and the protective hot plate 2, the width of the first gap 4 increases from the direction away from the heating member 3 to the direction close to the heating member 3, the heat transfer from the measuring hot plate 1 to the protective hot plate 2 can be reduced at the position where the width increases, and the strength of the measuring hot plate 1 can be satisfied due to the disposition of the first protrusion 11, and the gap area ratio can also satisfy the requirement.
The above-described embodiments are merely illustrative of one or more embodiments of the present invention, which are described in more detail and detail, but are not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (10)
1. A method for correcting a heat transfer area by a heat conductivity tester, wherein the heat conductivity tester comprises a metering hot plate (1) and a protective hot plate (2), and a gap is arranged between the metering hot plate (1) and the protective hot plate (2), and the method is characterized by comprising the following steps:
s1, obtaining a function curve of the position of the lowest temperature point at the gap along with the change of the temperature difference between the metering hot plate (1) and the protective hot plate (2) in a mathematical modeling mode;
s2, measuring the actual temperature deviation of the metering hot plate (1) and the protective hot plate (2) through experiments;
s3, substituting the actual temperature deviation obtained in the step S2 into the function curve of the step S1 to obtain the actual position of the temperature lowest point at the gap;
s4, acquiring the effective radius of the measuring hot plate (1) based on the actual position of the temperature lowest point, and calibrating the heat transfer area by using the effective radius of the measuring hot plate (1).
2. The method for modifying a heat transfer area of a thermal conductivity meter according to claim 1, wherein in step S1, the specific steps are as follows:
establishing a numerical model according to boundary conditions of the metering hot plate (1) and the protective hot plate (2) for simulation calculation so as to obtain a temperature difference value of the metering hot plate (1) and the protective hot plate (2);
carrying out temperature field diagram analysis on the obtained temperature difference between the measuring hot plate (1) and the protective hot plate (2) to determine the position of the lowest point of the temperature at the gap between the measuring hot plate (1) and the protective hot plate (2);
a, acquiring temperature difference values of a plurality of groups of metering hot plates (1) and protective hot plates (2) according to the step a; correspondingly, acquiring the positions of the lowest temperature points of the gaps of a plurality of groups of metering hot plates (1) and protective hot plates (2) according to the step b;
expressing the position of the temperature lowest point at the gap and the temperature difference value in a point value form; and then, fitting the obtained point values of the groups into a function curve to obtain a function relation of the position of the temperature lowest point at the gap position along with the change of the temperature difference.
3. The method for correcting a heat transfer area of a thermal conductivity meter according to claim 1 or 2, wherein in step S3, the actual position of the lowest point of temperature at the gap is obtained as follows;
4. The method for modifying heat transfer area of thermal conductivity meter according to claim 2, wherein in step a, the boundary condition of temperature is selected, and in the obtained temperature set, a temperature value is selected as a temperature constant value for simultaneous use of the metering hot plate (1) and the protection hot plate (2), and the corresponding power is adjusted to float up and down to obtain different temperature differences corresponding to different powers.
5. The method for correcting heat transfer area of thermal conductivity meter according to claim 1, wherein in step S4, the calculation formula of the calibrated heat transfer area is as follows:
wherein,
for the purpose of the calibrated heat transfer area,
in order to measure the original area of the hot plate (1),
in order to measure the original radius of the hot plate (1),
to measure the effective radius of the hot plate (1).
6. The method for correcting heat transfer area of thermal conductivity meter according to claim 2, wherein when the gap is an unsteady gap, in step S1, the geometric structure of the unsteady gap is used as a numerical model to perform simulation calculation, thereby calibrating the heat transfer area of the unsteady gap.
7. The method for correcting a heat transfer area of a thermal conductivity meter according to claim 2, wherein when the gap is a line contact, the heat transfer area of the line contact is calibrated by performing a simulation calculation using a geometry of the line contact as a numerical model in step S1.
8. The method for correcting the heat transfer area of a thermal conductivity meter according to claim 1, wherein the number of the metering hot plate (1) and the shielding hot plate (2) is two, and the heating member (3) is disposed between the two metering hot plates (1) and the two shielding hot plates (2).
9. The method for modifying a heat transfer area of a thermal conductivity meter according to claim 8, wherein the heating member (3) is a heating wire or a thin film heating sheet.
10. The method for modifying the heat transfer area of a thermal conductivity meter according to claim 9, wherein the thermal conductivity meter further comprises two cold plates (7), and two spaces for placing the sample (6) are respectively formed between the two cold plates (7) and the two metering hot plates (1).
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