High-temperature and high-pressure thermal conductivity thermal diffusion coefficient measuring device based on double-line transient plane heat source method

Abstract

The invention belongs to the field of thermal conductivity and thermal diffusion coefficient measurement, and particularly relates to a high-temperature and high-pressure thermal conductivity thermal diffusion coefficient measurement device based on a double-line transient plane heat source method, which comprises a sample, a thermocouple, a plane heat source heating wire, a heat insulation pipe, heat conduction metal columns, a heater and a pressure transmission medium, the surface of the sample and the surface of the heat conduction metal column are wrapped with a heat insulation pipe, the center of the pressure transmitting medium is provided with a hole-shaped sample bin, the heat insulation pipe is arranged in the hole-shaped sample bin, the heater is located between the heat insulation pipe and the pressure transmitting medium, and the sample comprises a first sample piece, a second sample piece and a third sample piece which are stacked from top to bottom. The thermocouple is horizontally arranged between the first sample piece and the second sample piece, and the plane heat source heating wire is arranged between the second sample piece and the third sample piece. Measurement errors and system errors can be reduced, and the experiment success rate is increased.

Description

Technical Field

[0001] The invention belongs to the field of thermal conductivity and thermal diffusivity measurement, and in particular relates to a high-temperature and high-pressure thermal conductivity and thermal diffusivity measurement device based on a double-line transient plane heat source method. Background Art

[0002] Thermal conductivity and thermal diffusivity are important thermophysical parameters of materials. In the past, due to technical limitations, there was a lack of means to measure materials under high pressure and high temperature and high pressure. The traditional transient plane heat source method can only directly measure the thermal diffusivity of the material, but cannot obtain thermal conductivity. The high-pressure time domain reflectometry method combined with diamond anvil can only obtain the thermal diffusivity of the material under high pressure conditions, while the two-line transient plane heat source method can measure the thermal diffusivity and thermal conductivity at the same time. However, the application of the two-line transient plane heat source method in high-pressure experiments is still relatively rare, and it is limited by factors such as the large resistance error of the heating wire that generates the plane heat source, the influence of the thermocouple's own specific heat capacity, and the unreasonable sample size, resulting in large measurement errors and system errors and low experimental success rate.

[0003] In order to solve the problems of insufficient high-temperature and high-pressure thermal conductivity measurement methods and large errors, it is necessary to design a more accurate high-temperature and high-pressure thermal conductivity thermal diffusivity measurement device based on the double-line transient plane heat source method to reduce measurement errors and system errors and improve the success rate of the experiment. Summary of the invention

[0004] In view of the technical defects of the prior art in measuring the thermal conductivity and thermal diffusivity of materials under high temperature and high pressure conditions, the present invention discloses a high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on a double-line transient plane heat source method, which improves the measurement accuracy and experimental success rate, and can be applied to the measurement of thermal conductivity and thermal diffusivity of various solid materials under high temperature and high pressure conditions, and specifically discloses the following technical solutions:

[0005] A high-temperature and high-pressure thermal conductivity and thermal diffusivity measuring device based on a double-line transient plane heat source method, comprising a sample, a thermocouple, a plane heat source heating wire, an insulating tube, a heat-conducting metal column, a heater and a pressure transmission medium, wherein the top and bottom of the sample are provided with heat-conducting metal columns, the surfaces of the sample and the heat-conducting metal column are wrapped with the insulating tube, the sample and the heat-conducting metal column are both located at the center of the insulating tube, a hole-shaped sample bin is provided at the center of the pressure transmission medium, the insulating tube is arranged in the hole-shaped sample bin, the heater is located between the insulating tube and the pressure transmission medium, the sample comprises sample slice 1, sample slice 2 and sample slice 3 stacked horizontally from top to bottom, the thermocouple is horizontally placed between sample slice 1 and sample slice 2, and the plane heat source heating wire is placed between sample slice 2 and sample slice 3.

[0006] Furthermore, the sample piece 1, the sample piece 2 and the sample piece 3 are circular pieces with the same specifications, and the connection point of the thermocouple coincides with the center of the circular piece.

[0007] Furthermore, it also includes a pulse power supply, which is connected in series with the planar heat source heating wire.

[0008] Furthermore, it also includes an insulating tube, which is arranged in the pressure transmission medium and is used to wrap the lead connecting the planar heat source heating wire and the pulse power supply.

[0009] Furthermore, it also includes a data collector, which is electrically connected to the thermocouple.

[0010] Furthermore, the aspect ratio of the sample is ≤1:8 to avoid the influence of lateral heat scattering on thermocouple measurement.

[0011] Furthermore, the diameter of the sample is 8 mm and the thickness is ≤ 1 mm.

[0012] Furthermore, the thickness of the thermocouple is ≤0.05 mm.

[0013] Furthermore, the planar heat source heating wires are arranged in a serpentine shape within the interlayer and are disc-shaped as a whole.

[0014] Furthermore, the planar heat source heating wire is made of molybdenum foil with a thickness of ≤0.03mm by laser or chemical etching, the diameter of the disk formed by the planar heat source heating wire is 8mm, and the interval between the planar heat source heating wires is ≤0.3mm.

[0015] The beneficial effects of the present invention are as follows: the present invention can be applied to the measurement of thermal conductivity and thermal diffusivity of various solid materials under high temperature and high pressure conditions, significantly improves experimental accuracy, greatly reduces measurement errors and system errors, and improves the success rate of experiments. A new type of heating wire is used as a planar heat source to effectively ensure the uniformity of heat generation by the heat source. By providing a reasonable size of the sample in the high-pressure experiment, the ideal state of one-dimensional heat conduction at the center of the sample is ensured, thereby greatly improving the accuracy of experimental measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the main body of the present invention;

[0017] Figure 2 It is a schematic diagram of the assembly of the thermocouple, planar heat source heating wire and sample of the present invention.

[0018] Among them, 1-sample piece one; 2-sample piece two; 3-sample piece three; 4-lead; 5-insulating tube; 6-heat-conducting metal column; 7-heater; 8-pressure transmission medium; 9-thermocouple; 10-insulating tube; 11-planar heat source heating wire. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Reference Figure 1 The present invention discloses a high-temperature and high-pressure thermal conductivity and thermal diffusivity measuring device based on a double-wire transient plane heat source method, which is mainly suitable for measuring the thermal conductivity and thermal diffusivity of solid materials with poor electrical conductivity, including a sample, a thermocouple 9, a plane heat source heating wire 11, an insulating tube 5, a heat-conducting metal column 6, a heater 7, a pressure transmission medium 8, a pulse power supply, an insulating tube 10, and a data collector. The top and bottom of the sample are provided with heat-conducting metal columns 6, the surfaces of the sample and the heat-conducting metal columns 6 are wrapped with the insulating tube 5, the sample and the heat-conducting metal columns 6 are both located at the center of the insulating tube 5, a hole is provided at the center of the pressure transmission medium 8 as a sample chamber, the insulating tube 5 is provided in the hole-shaped sample chamber, and the heater 7 is located between the insulating tube 5 and the pressure transmission medium 8.

[0021] like Figure 2 As shown, the aspect ratio of the sample is not greater than 1:8, which can effectively avoid the scattering of side heat from affecting the measurement of thermocouple 9. Specifically, the sample includes three circular sheets of the same specifications stacked horizontally from top to bottom, namely sample sheet 1, sample sheet 2 and sample sheet 3. Thermocouple 9 is horizontally placed between sample sheet 1 and sample sheet 2, and the connection point of thermocouple 9 coincides with the center of the circular sheet. The planar heat source heating wire 11 is placed between sample sheet 2 and sample sheet 3, and the center of the heating wire coincides with the center of the sample sheet. Taking the six-sided top press as an example, the recommended sample size is 8mm in diameter and less than or equal to 1mm in thickness.

[0022] The thermocouple 9 in this embodiment is used to monitor temperature changes. The volume of the thermocouple 9 should be as small as possible, especially the thickness, to prevent it from interfering with the temperature measurement. Taking the sample thickness of 1 mm as an example, the thickness of the thermocouple 9 is not greater than 0.05 mm.

[0023] The structure of the planar heat source heating wire 11 in this embodiment is shown in FIG. Figure 2 It is arranged in a serpentine shape in the interlayer and is disc-shaped as a whole. It is made of molybdenum foil with a thickness of no more than 0.03 mm by laser or chemical etching. Taking the heating wire with a diameter of 8 mm as an example, the interval between the heating wires should be no more than 0.3 mm to ensure that the heat source generated by the heating wire is close to the ideal plane heat source in the measurement.

[0024] Since the transient plane heat source method simulates a one-dimensional heat transfer process, the insulation tube 5 can play a role in heat preservation, thereby preventing heat from being lost from the outside. In this embodiment, zirconia can be used as the material of the insulation tube 5.

[0025] In this embodiment, the heat-conducting metal column 6 is close to both sides of the sample, and its diameter is the same as that of the sample. Its function is to quickly transfer the heat generated by the transient planar heat source to avoid heat accumulation, destroying the one-dimensional heat conduction state of the sample and affecting the measurement accuracy. Metal nickel can be used as a heat-conducting material.

[0026] In this embodiment, the heater 7 is made of metal or graphite, and heats the entire sample chamber in a low voltage and high current manner, so that the sample can be measured from room temperature to high temperature conditions.

[0027] Since the pressure generated by the high-pressure device must be achieved through the pressure transmission medium 8, for the six-sided top press, sintered pyrophyllite is recommended as the pressure transmission medium 8, and for the six- and eight-sided top press, magnesium oxide is recommended as the pressure transmission medium 8. When conducting high-temperature and high-pressure experiments, it is recommended that the pressure transmission medium 8 be baked and dehydrated in a muffle furnace in advance at high temperature to avoid the structural water of the minerals in it affecting the experiment at high temperature and causing unnecessary errors.

[0028] In this embodiment, the pulse power supply releases a single pulse current to generate a transient planar heat source through the planar heat source heating wire 11, and the heat heats the thermocouple 9 through the sample to cause the thermocouple 9 to generate an electrical signal.

[0029] As a preferred embodiment of the present invention, the lead wire 4 connecting the heating wire and the pulse power supply needs to be protected by a high-temperature resistant alumina tube to prevent short circuit leakage.

[0030] The data collector in this embodiment should respond quickly and collect the electrical signal of the thermocouple 9 in time for later data processing and analysis.

[0031] When the present invention measures the thermal conductivity and thermal diffusion coefficient of a fixed material, a pulsed direct current is released to the planar heat source heating wire 11 through a pulse power supply to heat the sample. The heat of the planar heat source heating wire 11 passes through the sample sheet 2 and reaches the thermocouple 9, which is converted into a thermoelectric signal by the thermocouple 9. The hot spot signal is collected and recorded by a data collector. The recorded thermal disturbance data can be fitted through a one-dimensional heat conduction equation to simultaneously obtain the thermal diffusion coefficient and thermal conductivity.

[0032] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on a double-line transient plane heat source method, characterized in that: It includes a sample, a thermocouple, a planar heat source heating wire, an insulating tube, a heat-conducting metal column, a heater and a pressure transmission medium. The top and bottom of the sample are provided with heat-conducting metal columns, the surfaces of the sample and the heat-conducting metal columns are wrapped with the insulating tube, the sample and the heat-conducting metal column are both located at the center of the insulating tube, a hole-shaped sample compartment is provided at the center of the pressure transmission medium, the insulating tube is arranged in the hole-shaped sample compartment, the heater is located between the insulating tube and the pressure transmission medium, the sample includes sample sheet one, sample sheet two and sample sheet three horizontally stacked from top to bottom, the thermocouple is horizontally placed between sample sheet one and sample sheet two, and the planar heat source heating wire is placed between sample sheet two and sample sheet three.

2. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 1 is characterized in that: The sample piece 1, sample piece 2 and sample piece 3 are circular pieces with the same specifications, and the connection point of the thermocouple coincides with the center of the circular piece.

3. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 1 is characterized in that: It also includes a pulse power supply, which is connected in series with the planar heat source heating wire.

4. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 3 is characterized in that: It also includes an insulating tube, which is arranged in the pressure transmission medium and is used to wrap the lead connecting the planar heat source heating wire and the pulse power supply.

5. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 1 is characterized in that: The device also includes a data collector, which is electrically connected to the thermocouple.

6. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 5, characterized in that: The aspect ratio of the sample is ≤1:8 to avoid the influence of scattering of side heat on thermocouple measurement.

7. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 1 is characterized in that: The sample has a diameter of 8 mm and a thickness of ≤1 mm.

8. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 1, characterized in that: The thickness of the thermocouple is ≤0.05 mm.

9. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 1, characterized in that: The planar heat source heating wires are arranged in a serpentine shape in the interlayer and are disc-shaped as a whole.

10. The high temperature and high pressure thermal conductivity and thermal diffusivity measuring device based on the double-line transient plane heat source method according to claim 9, characterized in that: The planar heat source heating wire is made of molybdenum foil with a thickness of ≤0.03mm by laser or chemical etching. The diameter of the disk formed by the planar heat source heating wire is 8mm, and the interval between the planar heat source heating wires is ≤0.3mm.

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