CN110376244B - Heat conductivity coefficient measuring device - Google Patents
Heat conductivity coefficient measuring device Download PDFInfo
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- CN110376244B CN110376244B CN201910768850.9A CN201910768850A CN110376244B CN 110376244 B CN110376244 B CN 110376244B CN 201910768850 A CN201910768850 A CN 201910768850A CN 110376244 B CN110376244 B CN 110376244B
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- G01N25/18—Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating 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
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Abstract
The invention discloses a heat conductivity coefficient measuring device, comprising: the first measuring unit comprises a first central heat-conducting column and a first measuring column; the first central heat conduction column is provided with a first fluid cavity, a heat source fluid inlet and a heat source fluid outlet, and the first fluid cavity is respectively connected with the heat source fluid inlet and the heat source fluid outlet; the first central heat-conducting column is connected with the first measuring column; the second measuring unit comprises a second central heat-conducting column and a second measuring column; the second central heat-conducting column is provided with a second fluid cavity, a cold source fluid inlet and a cold source fluid outlet, and the second fluid cavity is respectively connected with the cold source fluid inlet and the cold source fluid outlet; the second central heat-conducting column is connected with the second measuring column; be used for placing the test sample between the top of second measuring column and the bottom of first measuring column, and first measuring column and second measuring column all are equipped with temperature acquisition unit. The heat conductivity coefficient measuring device of the invention provides uniform and constant heat flow for the measuring device, and improves the measuring precision of the heat conductivity coefficient.
Description
Technical Field
The invention belongs to the technical field of measurement, and particularly relates to a heat conductivity coefficient measuring device.
Background
The internal temperature of the fuel cell stack needs to be maintained within a relatively stable range during operation to ensure the normal operation of the fuel cell stack. Therefore, the heat conduction and dissipation capacity of the galvanic pile plays a significant role in the overall performance of the galvanic pile. In order to measure the thermal conductivity of the stack, the thermal conductivity of the stack internals, in particular the bipolar plates and the carbon paper, must be measured. The conventional thermal conductivity measurement methods are based on the fourier heat conduction law, which calculates the thermal conductivity from the temperature change rate and the cross-sectional area. At present, the thermal conductivity of the material is generally measured by using a steady-state method, but the steady-state method has the following defects: the method has the advantages that uniform and stable heat flow is difficult to provide for a sample, so that measurement errors become large, and the problems comprise that the distribution of axial heat flow is not uniform, the heat loss from a test area to the outside is serious, the heat flow of a heat source is unstable and uniform, and the like; the influence of the contact thermal resistance cannot be excluded; when pressure is applied, the pressure is concentrated on one point, so that the pressure distribution is easy to be uneven, the measurement precision is influenced, meanwhile, the pressure is concentrated on a smaller point, the system is easy to be unstable, and the measurement error and the potential safety hazard are increased; the distribution of temperature measuring points is not scientific, and the actual temperature of the surface of the sample cannot be accurately obtained; the temperature difference of cold and heat sources is small, so that the error caused by the precision of the instrument is increased; meanwhile, the temperature of the sample is far higher than the room temperature, and when the heat conductivity coefficient of the sample is close to that of the heat insulating material, the loss of external heat at the sample is large, so that the heat flow is uneven, and the system error is increased. Therefore, it is desirable to provide a method capable of improving the measurement accuracy of the thermal conductivity.
Disclosure of Invention
The invention aims to provide a heat conductivity coefficient measuring device capable of improving the measurement accuracy of the heat conductivity coefficient.
In order to achieve the above object, the present invention provides a thermal conductivity measuring apparatus comprising: a first measurement unit comprising a first central thermally conductive post and a first measurement post; the first central heat conduction column is provided with a first fluid cavity, a heat source fluid inlet and a heat source fluid outlet, and the first fluid cavity is respectively connected with the heat source fluid inlet and the heat source fluid outlet; the first central heat-conducting column is connected with the first measuring column; a second measurement unit comprising a second central thermally conductive post and a second measurement post; the second central heat-conducting column is provided with a second fluid cavity, a cold source fluid inlet and a cold source fluid outlet, and the second fluid cavity is respectively connected with the cold source fluid inlet and the cold source fluid outlet; the second central heat-conducting column is connected with the second measuring column; the first measuring unit is located above the second measuring unit, a test sample is placed between the top of the second measuring column and the bottom of the first measuring column, and the first measuring column and the second measuring column are both provided with temperature collecting units.
Preferably, the thermal conductivity measuring device further comprises a pressure applying and device fixing unit, and the pressure applying and device fixing unit is respectively connected with the first measuring unit and the second measuring unit.
Preferably, the thermal conductivity measuring device further comprises: the first measuring unit further comprises a first heat insulation top cover, the first heat insulation top cover is arranged at the top of the first central heat conduction column, and a first caliper is arranged on the first heat insulation top cover and is connected with the pressure applying and device fixing unit through the first caliper; the second measuring unit further comprises a second heat insulation top cover, the second heat insulation top cover is arranged at the bottom of the second central heat conducting column, and the second heat insulation top cover is connected with the pressure applying and device fixing unit.
Preferably, the pressure applying and device fixing unit includes a first support plate, a second support plate and a support rack, the first support plate is connected with the support rack and the first heat-insulating top cover respectively; the second supporting plate is respectively connected with the supporting rack and the second heat-insulating top cover; and the first supporting plate is provided with a rotary stud, a pressure testing unit and a rotating handle.
Preferably, the thermal conductivity measuring device further comprises: a heat insulation unit disposed outside the first and second measurement units.
Preferably, the insulation unit comprises an inner insulation layer and an outer insulation layer, the inner insulation layer covers the first measuring column and the second measuring column; the outer heat insulation layer covers the inner heat insulation layer, the first central heat conduction column and the second central heat conduction column.
Preferably, the first and second fluid chambers are both annular chambers.
Preferably, the diameter of the first central heat-conducting column is larger than that of the first measuring column, and the diameter of the second central heat-conducting column is larger than that of the second measuring column.
Preferably, the heat source fluid inlet is provided below the heat source fluid outlet; the cold source fluid inlet is arranged above the cold source fluid outlet.
Preferably, a plurality of temperature acquisition units are arranged on the first measuring column, wherein 1 temperature acquisition unit is arranged on the first measuring column and abuts against the sample; and the second measuring column is provided with a plurality of temperature acquisition units, wherein 1 temperature acquisition unit is arranged at the position, which is close to the sample, on the second measuring column.
The invention has the beneficial effects that: the heat conductivity coefficient measuring device simultaneously heats the test sample by the cold source fluid and the heat source fluid, provides uniform and constant heat flow for the measuring device, reduces the measurement error caused by uneven heat flow to the minimum, simultaneously reduces the cold end temperature to 0 ℃ or even lower by the cold source fluid, enlarges the temperature distribution range, ensures that the temperature of the test sample is close to the room temperature, reduces the heat loss to the maximum extent, can fully ensure that the measurement result is not influenced by heat flow loss, reduces the measurement error and improves the measurement precision of the heat conductivity coefficient.
The heat conductivity coefficient measuring device provided by the invention has the advantages that the heat conductivity coefficient of the sample is measured under different pressure states by the aid of the large-size pressurizing studs and the plurality of pressure testing sensors of the pressure testing unit and the pressure transmission points are dispersed, stress conditions of all positions can be monitored by the aid of the plurality of pressure sensors at different positions, the test sample can be subjected to more uniform pressure, and a measuring result is more accurate.
The heat conductivity coefficient measuring device ensures that the temperature is closer to a true value and the accuracy of a result through optimized temperature acquisition and measurement point distribution.
The system of the present invention has other features and advantages which will be apparent from or are set forth in detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the invention.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings. Wherein like reference numerals generally refer to like parts throughout the exemplary embodiments of the invention.
Fig. 1 shows a structural connection diagram of a thermal conductivity measurement apparatus according to an embodiment of the present invention.
Fig. 2 shows a profile of a thermal conductivity measurement apparatus according to an embodiment of the present invention.
Fig. 3 shows a wiring diagram of a part of the temperature acquisition unit wiring of the thermal conductivity measuring apparatus according to one embodiment of the present invention.
Fig. 4 is a diagram illustrating a CFD simulation result of a thermal conductivity measuring apparatus according to an embodiment of the present invention.
Description of the reference numerals
1. A first central thermally conductive post; 11. a heat source fluid inlet; 12. a heat source fluid outlet; 13. a first fluid chamber; 15. a first thermally insulating top cover; 2. a first measuring column; 20. an inner insulating layer; 21. an outer insulating layer; 22. a thermal insulation layer interface; 3. a second central thermally conductive post; 31. a cold source fluid inlet; 32. a cold source fluid outlet; 33. a second fluid chamber; 4. a second measuring column; 6. a temperature acquisition unit; 61. a thermocouple sensor wire; 7. a first support plate; 71. a pressure test unit; 72. rotating the stud; 73. rotating the handle; 8. a second support plate; 9. a support stand.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The invention provides a heat conductivity coefficient measuring device, comprising: the first measuring unit comprises a first central heat-conducting column and a first measuring column; the first central heat conduction column is provided with a first fluid cavity, a heat source fluid inlet and a heat source fluid outlet, and the first fluid cavity is respectively connected with the heat source fluid inlet and the heat source fluid outlet; the first central heat-conducting column is connected with the first measuring column; a second measurement unit comprising a second central thermally conductive post and a second measurement post; the second central heat-conducting column is provided with a second fluid cavity, a cold source fluid inlet and a cold source fluid outlet, and the second fluid cavity is respectively connected with the cold source fluid inlet and the cold source fluid outlet; the second central heat-conducting column is connected with the second measuring column; the first measuring unit is located above the second measuring unit, a test sample is placed between the top of the second measuring column and the bottom of the first measuring column, and the first measuring column and the second measuring column are both provided with temperature collecting units.
Specifically, the constant-temperature heat source fluid provided by the thermostat enters the first fluid cavity from the heat source fluid inlet of the first central heat-conducting column and flows back to the thermostat from the heat source fluid outlet of the first central heat-conducting column. Constant-temperature cold source fluid provided by the thermostat enters the second fluid cavity from a cold source fluid inlet of the second central heat-conducting column and flows back to the thermostat from a cold source fluid outlet of the second central heat-conducting column. The first central thermally conductive post and the first measurement post are integrally formed to avoid thermal contact resistance between the first fluid chamber and the first measurement post. The second central thermally conductive post and the second measurement post are integrally formed to avoid thermal contact resistance between the second fluid chamber and the second measurement post. The first central heat-conducting column and the second central heat-conducting column are symmetrically arranged, a test sample is clamped between the first measuring column and the second measuring column, and the required diameter of the test sample is the same as that of the measuring column. When a heat source fluid flows in and a cold source fluid flows in, the first fluid cavity transmits heat of a constant-temperature heat source of the fluid to the first central heat-conducting column, the first central heat-conducting column transmits the heat to the first measuring column, and then transmits the heat to a test sample, the second fluid cavity transmits the heat of the constant-temperature cold source of the fluid to the second central heat-conducting column, and the second central heat-conducting column transmits the heat to the second measuring column, and then transmits the heat to the test sample, so that uniform and constant heat flow is provided for the measuring device. The temperature acquisition unit sets up on first measuring column and second measuring column, gathers the temperature of first measuring column and second measuring column multiple spot, and then adopts the heat conduction law of Fourier to calculate the coefficient of heat conductivity of test sample.
The thermal conductivity measuring apparatus according to the exemplary embodiment forms a constant temperature difference on both sides of a sample by two constant temperature fluids, a cold source fluid and a hot source fluid, provides a uniform and constant heat flow to the measuring apparatus, through reasonable temperature setting of cold and heat sources and two tight heat insulation layers of the inner layer and the outer layer, the heat flow passing through the sample is ensured to be uniform and constant, so that the measurement error caused by uneven heat flow is reduced to the minimum, meanwhile, the cold source is cooled by using a constant-temperature cold fluid, so that the temperature of the cold end is reduced to 0 ℃ or even lower, the temperature distribution range is expanded, on one hand, a larger temperature difference is realized to reduce the system error of temperature measurement, on the other hand, the temperature of a test sample is close to the room temperature, the heat loss is reduced to the maximum extent, the measuring result can be fully ensured not to be influenced by heat flow loss, the measuring error is reduced, and the measuring precision of the heat conductivity coefficient is improved.
Preferably, the thermal conductivity measuring device further comprises a pressure applying and device fixing unit, and the pressure applying and device fixing unit is connected with the first measuring unit and the second measuring unit respectively.
Preferably, the thermal conductivity measuring device further includes: the first measuring unit further comprises a first heat insulation top cover, the first heat insulation top cover is arranged at the top of the first central heat conducting column, and a first caliper is arranged on the first heat insulation top cover and is connected with the pressure applying and device fixing unit through the first caliper; the second measurement unit further comprises a second heat insulation top cover, the second heat insulation top cover is arranged at the bottom of the second central heat conduction column, and the second heat insulation top cover is connected with the pressure applying and device fixing unit.
Specifically, a first heat insulation top cover is connected with the middle part of a first central heat conduction column through a connecting stud, a sealing ring is arranged at the top parts of the first heat insulation top cover and the first central heat conduction column, and a first caliper is arranged on the first heat insulation top cover and is connected with a pressure applying and device fixing unit through the first caliper; the second heat insulation top cover is connected with the middle part of the second central heat conduction column through a connecting stud, a sealing ring is arranged at the top of the second heat insulation top cover and the top of the second central heat conduction column, and the second heat insulation top cover is connected with the pressure applying and device fixing unit.
Preferably, the pressure applying and device fixing unit comprises a first support plate, a second support plate and a support rack, wherein the first support plate is respectively connected with the support rack and the first heat insulation top cover; the second supporting plate is respectively connected with the supporting rack and the second heat-insulating top cover; the first supporting plate is provided with a rotary stud, a pressure testing unit and a rotating handle.
Specifically, the first caliper is connected with a first supporting plate of the pressure applying and device fixing unit, the second caliper is connected with a second supporting plate of the pressure applying and device fixing unit, and the supporting rack is connected with the first supporting plate and the second supporting plate. The first supporting plate is provided with a rotary stud, a pressure testing unit and a rotating handle. The diameter of the rotary stud is the same as that of the first heat-insulating top cover, the length of the rotary stud is about 10cm, and the rotary stud is fixed in the horizontal direction through calipers on the first heat-insulating top cover. Can provide even controllable pressure to first measuring element through rotatory double-screw bolt, the pressure test unit is equipped with 7 pressure sensor, and 7 pressure sensor read out the pressure value and guarantee that pressure uniformity is stable.
According to the heat conductivity coefficient measuring device of the exemplary embodiment, the pressure transmission points are dispersed through the large-sized pressurizing studs and the plurality of pressure testing sensors of the pressure testing unit, so that the test sample can be subjected to more uniform pressure, and the measuring result is more accurate.
In one example, if the stud, the pressure sensor and the support rack are replaced by the connecting piece on the universal testing machine, larger pressure can be applied to the sample, and higher requirements can be met.
Preferably, the thermal conductivity measuring device further includes: and the heat insulation unit is arranged on the outer sides of the first measuring unit and the second measuring unit.
Preferably, the heat insulation unit comprises an inner heat insulation layer and an outer heat insulation layer, and the inner heat insulation layer coats the first measuring column and the second measuring column; the outer insulating layer covers the inner insulating layer, the first central heat-conducting column and the second central heat-conducting column.
Specifically, the inner heat insulation layer covers the first measuring column and the second measuring column, and the outer heat insulation layer covers the inner heat insulation layer, the first central heat conduction column and the second central heat conduction column. The inner and outer heat insulation layers are both made of foam heat insulation materials, and small holes for accommodating thermocouple sensor leads to pass through are reserved on the inner and outer heat insulation layers. Prevent first measuring column and second measuring column to external heat loss completely through the isolation layer, guarantee that the heat flow uniformity through the sample is stable, guarantee the measuring accuracy.
Preferably, the first fluid chamber and the second fluid chamber are both annular chambers.
Preferably, the diameter of the first central heat-conducting column is larger than that of the first measuring column, and the diameter of the second central heat-conducting column is larger than that of the second measuring column.
Specifically, the diameter of the first central heat-conducting column is slightly larger than that of the first measuring column, and the diameter of the second central heat-conducting column is slightly larger than that of the second measuring column. The first fluid cavity, the first central heat conduction column and the first measuring column are integrally formed, so that uneven thermal contact resistance between the first fluid cavity and the first measuring column is avoided, and the measuring precision is improved. The top surface of the first measuring column is connected with the bottom surface of the first central heat-conducting column, and the diameter of the first central heat-conducting column is larger than that of the first measuring column.
The second fluid cavity, the second central heat conduction column and the second measuring column are integrally formed, so that uneven thermal contact resistance between the second fluid cavity and the second measuring column is avoided, and the measuring precision is improved. The bottom surface of the second measuring column is connected with the top surface of the second central heat-conducting column, and the diameter of the second central heat-conducting column is larger than that of the second measuring column.
Preferably, the heat source fluid inlet is arranged below the heat source fluid outlet; the cold source fluid inlet is arranged above the cold source fluid outlet.
Specifically, through theoretical analysis and experiments, a heat source fluid inlet is arranged below a heat source fluid outlet, and a cold source fluid inlet is arranged above a cold source fluid outlet. After the heat source fluid enters the fluid cavity, the fluid level in the first fluid cavity is raised, and after the fluid level reaches a certain height, the fluid overflows from the heat source fluid outlet. After the cold source fluid enters the fluid cavity, the fluid level in the second fluid cavity rises, and the fluid overflows from the cold source fluid outlet after reaching a certain height, so that uniform and constant heat flow is provided for the measuring device.
Preferably, the first measuring column is provided with a plurality of temperature acquisition units, wherein 1 temperature acquisition unit is arranged at a position, close to the sample, on the first measuring column; a plurality of temperature acquisition units are arranged on the second measuring column, wherein 1 temperature acquisition unit is arranged at the position, close to the sample, of the second measuring column.
The sample is clamped between the first measuring column and the second measuring column, and heat flows from the first measuring column to the second measuring column. Due to the one-dimensional heat transfer, the heat flow density is equal everywhere. From the fourier law of thermal conductivity, one can obtain:
where Q is the heat flow from the heat source through the sample to the cold source, THIs a uniform constant heat source temperature, TLTo equalize cold source temperature, Δ TMIs the temperature difference, k, between two adjacent temperature measuring points on the first measuring columnMThermal coefficient of conductivity, L, for the first measurement columnMThe distance between two adjacent temperature measuring points is represented by delta Ts, the temperature difference between the upper surface and the lower surface of the sample, ks is the heat conductivity coefficient of the sample, Ls is the thickness of the sample, and A is the cross-sectional area of the sample and the measuring column.
Q is one-dimensional heat transfer for the heat flow, and no heat dissipation to the outside in the radial direction exists. I.e. is insulated from the outside.
Through the formula, the thermal conductivity coefficient ks of the sample can be obtained.
The purpose of setting a plurality of temperature measuring points is to reduce the error of the heat flow Q; the purpose of providing two temperature measurement points very close to the upper and lower surfaces of the sample is to obtain the temperature of the upper and lower surfaces of the sample as accurately as possible. Because the two temperature measuring points are actually at a slight distance from the sample, the temperature difference between the two temperature measuring points cannot be simply calculated by equating the temperature of the two temperature measuring points to the temperature of the upper surface and the lower surface of the sample, and the temperature difference can be corrected by the heat flow and the distance between the two temperature measuring points and the sample. If the actual measurement is not performed, a system error of about 2-4% will be generated.
Specifically, the temperature acquisition unit adopts a thermocouple sensor, the measurement part of the thermocouple sensor extends into the inner centers of the first measurement column and the second measurement column, and the heat conductivity coefficient measurement device acquires the distribution of measurement points through optimized temperature, so that the temperature is ensured to be closer to a true value, and the accuracy of the result is ensured. The first thermocouple sensor, the second thermocouple sensor and the third thermocouple sensor are arranged on the first measuring column, the second thermocouple sensor, the fourth thermocouple sensor, the fifth thermocouple sensor and the sixth thermocouple sensor are arranged on the second measuring column, the third thermocouple sensor is arranged at a position, close to a sample, of 1-2 mm on the first measuring column, the fourth thermocouple sensor is arranged at a position, close to a sample, of 1-2 mm on the second measuring column, and the purpose is to obtain the temperatures of the upper surface and the lower surface of the sample as accurately as possible. During the experiment, uniform and stable heat flow passes through a test sample from top to bottom, the temperature of each test point read by the thermocouple sensor is read, and the thermal resistance (contact thermal resistance + material thermal resistance) at the moment can be obtained through the Fourier law.
According to the Fourier heat conduction law, the relationship between the thermal resistance and the thermal conductivity is as follows:
where Q is the heat flow from the heat source through the sample to the heat sink, T2Is the temperature of the heat source, T1Is the cold source temperature, delta x is the heat conduction distance/sample thickness, K is the sample heat conduction coefficient, A is the sample cross-sectional area, and Rth is the sample thermal resistance.
Since the surface of a solid always has a certain roughness, contact thermal resistance is certain to exist at the interface of the two solids for heat transfer. Therefore, the calculated thermal resistance derived in the foregoing equation (2) actually includes two parts: the thermal contact resistance of the sample with the measurement column and the actual thermal resistance of the sample itself. The calculated thermal resistance is designed to be Rth, the actual thermal resistance of the sample is Rs, the contact thermal resistance is Rc, the thickness of the sample is deltax,
at sample thickness Δ x, Rth 2Rc + Rs
At a sample thickness of 2 Δ x, Rth ═ 2Rc +2Rs
At a sample thickness of 3 Δ x, Rth ═ 2Rc +3Rs
……
When the thickness of the sample is n delta x, Rth is 2Rc + nRs
And measuring Rth values under different thicknesses, and making an n-Rth linear regression line, wherein the slope of the line is the true thermal resistance Rs of the sample, and the intercept is the contact thermal resistance between the sample and the measuring column. Therefore, by measuring samples with different thicknesses, the influence of contact thermal resistance can be eliminated.
Specifically, a thermostat is used for introducing constant-temperature heat source fluid into a heat source fluid inlet and introducing constant-temperature cold source fluid into a cold source fluid inlet, so that a certain temperature difference is kept between the heat source and the cold source. The sample with the same diameter as the first and second measuring columns is clamped between the first and second measuring columns, and the rotary stud is tightened to apply the required pressure to the first measuring cell. Then an insulating layer is sleeved on the thermocouple sensor lead. Respectively placing a first thermocouple sensor, a second thermocouple sensor, a third thermocouple sensor, a fourth thermocouple sensor, a fifth thermocouple sensor and a sixth thermocouple sensor from the top of the first measuring column to the bottom of the second measuring column, setting the distance between adjacent thermocouple sensors (except the third thermocouple sensor and the fourth thermocouple sensor) to be L, and setting the thermal conductivity coefficients of the first measuring column and the second measuring column to be kMThe cross section area is A, the thickness of the test sample is D, the cross section area is equal to A, the distance from the third thermocouple sensor and the fourth thermocouple sensor to the contact surface of the test sample is D, and the temperature T of the 6 thermocouple sensors is read after the temperature is stabilized1～T6。
The temperature gradient in the first measuring column and the second measuring column is as follows: Δ T ═ T1-T2+T5-T6)/2L，T1、T2、T5、T6And the L parameter are known, so that the delta T can be obtained. And further obtaining the value of the thermal conductivity and the contact thermal resistance of the test sample as follows: r ═ kMAΔT/(T4-T3-2dΔT)，A、kM、ΔT、T4、T3And d parameters are known, so that R can be obtained.
Measuring the test samples with the thicknesses of D, 2D and 3D … … nD respectively to obtain the linear relation between R and n, making the linear relation between R and n to obtain a regression curve, wherein the slope of the regression curve is the contact thermal resistance of the test sample with the thickness of D, and the thermal conductivity coefficient can be obtained, so that the introduction coefficient is not influenced by the contact thermal resistance. By the method of variable thickness measurement linear regression, the influence of contact thermal resistance is eliminated, and the measurement accuracy is further improved.
Example one
Fig. 1 shows a structural connection diagram of a thermal conductivity measurement apparatus according to an embodiment of the present invention. Fig. 2 shows a profile of a thermal conductivity measurement apparatus according to an embodiment of the present invention.
With reference to fig. 1 and 2, a thermal conductivity measuring apparatus includes: the measuring device comprises a first measuring unit, a second measuring unit and a measuring unit, wherein the first measuring unit comprises a first central heat-conducting column 1 and a first measuring column 2; the first central heat conduction column 1 is provided with a first fluid cavity 13, a heat source fluid inlet 11 and a heat source fluid outlet 12, and the first fluid cavity 13 is respectively connected with the heat source fluid inlet 11 and the heat source fluid outlet 12; the first central heat-conducting column 1 is connected with the first measuring column 2; a second measuring unit comprising a second central thermally conductive post 3 and a second measuring post 4; the second central heat-conducting column 3 is provided with a second fluid cavity 33, a cold source fluid inlet 31 and a cold source fluid outlet 32, and the second fluid cavity 33 is respectively connected with the cold source fluid inlet 31 and the cold source fluid outlet 32; the second central heat-conducting column 3 is connected with a second measuring column 4; the first measuring unit is located the top of second measuring unit, is used for placing the test sample between the top of second measuring column 4 and the bottom of first measuring column 2, and just first measuring column 2 and second measuring column 4 all are equipped with temperature acquisition unit 6.
The device for measuring the thermal conductivity further comprises a pressure applying and device fixing unit, and the pressure applying and device fixing unit is connected with the first measuring unit and the second measuring unit respectively.
Wherein the thermal conductivity measuring device further comprises: the first measuring unit further comprises a first heat insulation top cover 15, the first heat insulation top cover 15 is arranged at the top of the first central heat conduction column 1, the first heat insulation top cover 15 is connected with the first central heat conduction column 1 through a connecting stud, and sealing rings are arranged at the top of the first heat insulation top cover 15 and the top of the first central heat conduction column 1; the first insulating top cover 15 is provided with a first caliper which is connected with the pressure applying and device fixing unit; the second measuring unit further comprises a second heat insulation top cover, the second heat insulation top cover is arranged at the bottom of the second central heat conducting column 3, and the second heat insulation top cover is connected with the pressure applying and device fixing unit.
The pressure applying and device fixing unit comprises a first supporting plate 7, a second supporting plate 8 and a supporting rack 9, wherein the first supporting plate 7 is respectively connected with the supporting rack 9 and a first heat insulation top cover 15; the second supporting plate 8 is respectively connected with the supporting rack 9 and the second heat-insulating top cover; the first support plate 7 is provided with a rotary stud 72, a pressure test unit 71 and a rotating handle 73.
Wherein the thermal conductivity measuring device further comprises: and the heat insulation unit is arranged on the outer sides of the first measuring unit and the second measuring unit.
The heat insulation unit comprises an inner heat insulation layer 20 and an outer heat insulation layer 21, wherein the inner heat insulation layer 20 coats the first measuring column 2 and the second measuring column 4; the outer heat insulation layer 21 covers the inner heat insulation layer 20, the first central heat conduction column 1 and the second central heat conduction column 3.
Wherein the first fluid chamber 13 and the second fluid chamber 33 are both annular chambers.
Wherein, the diameter of the first central heat-conducting column 1 is larger than that of the first measuring column 2, and the diameter of the second central heat-conducting column 3 is larger than that of the second measuring column 4.
Wherein the heat source fluid inlet 11 is arranged below the heat source fluid outlet 12; the cold source fluid inlet 31 is disposed above the cold source fluid outlet 32.
Wherein, a plurality of temperature acquisition units 6 are arranged on the first measuring column 2, wherein 1 temperature acquisition unit 6 is arranged at the part of the first measuring column 2, which is close to the sample; a plurality of temperature acquisition units 6 are arranged on the second measuring column 4, wherein 1 temperature acquisition unit 6 is arranged on the second measuring column 4 and is abutted against the sample.
Fig. 3 shows a wiring diagram of a part of the temperature acquisition unit 6 of the thermal conductivity measuring apparatus according to an embodiment of the present invention. Fig. 4 is a diagram illustrating a CFD simulation result of a thermal conductivity measuring apparatus according to an embodiment of the present invention.
As shown in fig. 3, the thermocouple sensor wire 61 passes through the small hole on the inner and outer heat insulation layers, and the thermocouple sensor wire 61 is routed as shown in the figure. As shown in fig. 4, the thermal simulation result shows that the inner and outer thermal insulation layers can completely prevent the first measuring unit and the second measuring unit from dissipating external heat, so that the uniformity and stability of heat flow passing through the sample are ensured, and the test accuracy is ensured.
The use method of the thermal conductivity measuring device is as follows:
step 1: when in use, the heat conductivity coefficient measuring device is placed on a horizontal plane. The test sample is cut or sheared into a cylinder having the same cross section as the first measuring cylinder 2 and the second measuring cylinder 4 and a thickness D, and the test sample is clamped between the first measuring cylinder 2 and the second measuring cylinder 4.
Step 2: the rotary stud 72 is tightened to apply the required pressure to the first measurement unit, fine-tuning the test sample position until the readings of the 7 pressure sensors are consistent. The thickness of the sample is recommended to be about 0.1-5 cm so as to reduce experimental errors.
And 3, step 3: and respectively introducing constant-temperature heat source fluid and constant-temperature cold source fluid into the first central heat-conducting column 13 and the second central heat-conducting column 33 according to the figure, and keeping the required temperature difference between the heat source and the cold source.
And 4, step 4: the inner and outer insulating layers are wrapped on the first measuring column 2, the second measuring column 4, the first central heat-conducting column 13 and the second central heat-conducting column 33, and a thermocouple sensor lead 61 is led out.
And 5: waiting for 5 to 10 minutes, recording the temperature value T of each thermocouple sensor after the reading is stable1～T6。
Step 6: samples (2D, 3D … nD) of different thicknesses were replaced and the temperature values for each set were recorded.
And 7: for a set of temperature values, adjacent thermocouple sensorsThe spacing between (except for the third thermocouple sensor and the fourth thermocouple sensor) is L, kMThe cross section area is A, the thickness of the test sample is D, the cross section area is equal to A, the distance from the third thermocouple sensor and the fourth thermocouple sensor to the contact surface of the test sample is D, and the temperature T of the 6 thermocouple sensors is read after the temperature is stable1～T6。
The temperature gradient in the first measuring column 2 and the second measuring column 4 is as follows:
ΔT＝(T1-T2+T5-T6)/2L，
wherein, Delta T is temperature gradient, T1Is the temperature, T, of the first thermocouple sensor2Is the temperature, T, of the second thermocouple sensor5Is the temperature, T, of the fifth thermocouple sensor6L is a distance between adjacent thermocouple sensors (except for the third thermocouple sensor and the fourth thermocouple sensor) at the temperature of the sixth thermocouple sensor.
The value of the thermal conductivity and the contact thermal resistance of the test sample is obtained by adopting the following formula
R＝kMAΔT/(T4-T3-2dΔT)，
Wherein R is the heat conductivity and the contact thermal resistance of the test sample, A is the cross-sectional area of the test sample, and kMIs the thermal conductivity, T, of the first measuring column 2 and the second measuring column 44Is the temperature, T, of the fourth thermocouple sensor3Is the temperature of the third thermocouple sensor and d is the distance from the third thermocouple sensor and the fourth thermocouple sensor to the test sample contact surface.
And 8: and (3) solving R corresponding to the test samples with the measured thicknesses of D, 2D and 3D … … nD respectively to obtain a linear relation between R and n, and making the linear relation between R and n to obtain a regression curve, wherein the slope of the regression curve is the contact thermal resistance of the test sample with the measured thickness of D, and the thermal conductivity coefficient of the test sample can be obtained by R-contact thermal resistance.
While embodiments of the present invention have been described above, the above description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the illustrated embodiments.
Claims (7)
1. A thermal conductivity measurement device, comprising:
a first measurement unit comprising a first central thermally conductive post and a first measurement post; the first central heat conduction column is provided with a first fluid cavity, a heat source fluid inlet and a heat source fluid outlet, and the first fluid cavity is respectively connected with the heat source fluid inlet and the heat source fluid outlet; the first central heat-conducting column is connected with the first measuring column;
a second measurement unit comprising a second central thermally conductive post and a second measurement post; the second central heat-conducting column is provided with a second fluid cavity, a cold source fluid inlet and a cold source fluid outlet, and the second fluid cavity is respectively connected with the cold source fluid inlet and the cold source fluid outlet; the second central heat-conducting column is connected with the second measuring column;
the first measuring unit is positioned above the second measuring unit, a test sample is placed between the top of the second measuring column and the bottom of the first measuring column, and the first measuring column and the second measuring column are both provided with temperature acquisition units;
the device further comprises a pressure applying and device fixing unit, and the pressure applying and device fixing unit is respectively connected with the first measuring unit and the second measuring unit;
the first measuring unit further comprises a first heat insulation top cover, the first heat insulation top cover is arranged at the top of the first central heat conduction column, and a first caliper is arranged on the first heat insulation top cover and is connected with the pressure applying and device fixing unit through the first caliper;
the second measuring unit further comprises a second heat-insulating top cover, the second heat-insulating top cover is arranged at the bottom of the second central heat-conducting column, and the second heat-insulating top cover is connected with the pressure applying and device fixing unit;
the pressure applying and device fixing unit comprises a first supporting plate, a second supporting plate and a supporting rack, wherein the first supporting plate is respectively connected with the supporting rack and a first heat insulation top cover; the second supporting plate is respectively connected with the supporting rack and the second heat-insulating top cover; and the first supporting plate is provided with a rotary stud, a pressure testing unit and a rotating handle.
2. The thermal conductivity measurement device according to claim 1, further comprising: a heat insulation unit disposed outside the first and second measurement units.
3. The thermal conductivity measurement device of claim 2, wherein the insulation unit comprises an inner insulation layer and an outer insulation layer, the inner insulation layer encasing the first and second measurement columns; the outer thermal insulation layer covers the inner thermal insulation layer, the first central heat conduction column and the second central heat conduction column.
4. The thermal conductivity measurement device of claim 1, wherein the first and second fluid chambers are both annular chambers.
5. The thermal conductivity measurement device of claim 4, wherein the diameter of the first central thermally conductive post is greater than the diameter of the first measurement post, and the diameter of the second central thermally conductive post is greater than the diameter of the second measurement post.
6. The thermal conductivity measurement device of claim 1, wherein the heat source fluid inlet is disposed below the heat source fluid outlet; the cold source fluid inlet is arranged above the cold source fluid outlet.
7. The thermal conductivity measuring apparatus according to claim 1, wherein a plurality of temperature collecting units are provided on the first measuring column, wherein 1 temperature collecting unit is provided on the first measuring column at a portion abutting against the sample; and the second measuring column is provided with a plurality of temperature acquisition units, wherein 1 temperature acquisition unit is arranged at the position, which is close to the sample, on the second measuring column.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB911849A (en) * | 1959-04-15 | 1962-11-28 | Commissariat Energie Atomique | Improvements in or relating to apparatus for measuring the coefficient of thermal conductivity of solid materials |
| CN101184610A (en) * | 2005-01-24 | 2008-05-21 | 特莫瓦克有限公司 | Evacuated thermal insulation panel |
| CN101393148A (en) * | 2008-10-22 | 2009-03-25 | 河北工业大学 | Test device for coating heat dispersion and test method thereof |
| CN102621179A (en) * | 2012-03-20 | 2012-08-01 | 北京航空航天大学 | Device and method for measuring heat conductivity coefficient of barred body material |
| CN104535609A (en) * | 2014-12-26 | 2015-04-22 | 怡维怡橡胶研究院有限公司 | Device for determining heat-conductivity coefficient |
| CN109001252A (en) * | 2018-06-28 | 2018-12-14 | 西南电子技术研究所（中国电子科技集团公司第十研究所） | Test device of thermal conductivity coefficient |
| CN109991266A (en) * | 2019-03-22 | 2019-07-09 | 上海工程技术大学 | The laser of interface heat exchange coefficient and material thermal conductivity heats measuring device and method |
-
2019
- 2019-08-20 CN CN201910768850.9A patent/CN110376244B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB911849A (en) * | 1959-04-15 | 1962-11-28 | Commissariat Energie Atomique | Improvements in or relating to apparatus for measuring the coefficient of thermal conductivity of solid materials |
| CN101184610A (en) * | 2005-01-24 | 2008-05-21 | 特莫瓦克有限公司 | Evacuated thermal insulation panel |
| CN101393148A (en) * | 2008-10-22 | 2009-03-25 | 河北工业大学 | Test device for coating heat dispersion and test method thereof |
| CN102621179A (en) * | 2012-03-20 | 2012-08-01 | 北京航空航天大学 | Device and method for measuring heat conductivity coefficient of barred body material |
| CN104535609A (en) * | 2014-12-26 | 2015-04-22 | 怡维怡橡胶研究院有限公司 | Device for determining heat-conductivity coefficient |
| CN109001252A (en) * | 2018-06-28 | 2018-12-14 | 西南电子技术研究所（中国电子科技集团公司第十研究所） | Test device of thermal conductivity coefficient |
| CN109991266A (en) * | 2019-03-22 | 2019-07-09 | 上海工程技术大学 | The laser of interface heat exchange coefficient and material thermal conductivity heats measuring device and method |
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