Device and method for synchronously measuring thermal conductivity and thermal diffusion coefficient of mineral rock under extreme conditions

Abstract

The invention belongs to the technical field of material physical property testing, and discloses a device and a method for synchronously measuring thermal conductivity and thermal diffusion coefficient of mineral rock under extreme conditions, the device comprises a power supply module, a pulse heating module and a data acquisition module; wherein the power supply module is used for supplying power to the pulse heating module and the data acquisition module; the pulse heating module is used for performing pulse heating on the sample; and the data acquisition module is used for acquiring voltage signals of the pulse heating module and the external thermocouple. According to the invention, the problems of incapability of synchronously and accurately measuring kappa and D, weak anti-interference capability and low data precision in the prior art are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of material property testing and is applicable to the fields of earth science, planetary science and materials science. It specifically relates to a device and method for synchronously measuring the thermal conductivity and thermal diffusivity of mineral rocks under extreme conditions. Background Art

[0002] The commonly used method for accurately and efficiently measuring the thermophysical parameters of minerals and rocks under high temperature and high pressure conditions is the pulse heating method, which requires the use of a large-volume press for heating and pressurizing. The sample is placed in a large multi-faceted anvil press, and the temperature is monitored by a thermocouple (usually K-type or C-type). The traditional measurement method has the following shortcomings: (1) An oscilloscope is required to record the voltage signal of the pulse heater and the thermoelectromotive force signal of the sample caused by pulse heating. Since the accuracy of the oscilloscope cannot distinguish the microvolt-level thermocouple signal, a signal amplifier needs to be introduced into the measurement circuit. However, the response time of the amplifier is usually more than 10ms, which will cause a delay in the thermocouple signal, seriously affecting the calculation results of the thermophysical parameters; (2) When calculating the thermophysical parameters, it is necessary to accurately know the power loaded on the planar heat source, but the traditional method cannot obtain the accurate planar heat source power; (3) The traditional measurement method requires switching circuits back and forth to measure and record different parameters, which is inefficient. In response to the above shortcomings, the present invention has developed an instrument device based on the pulse heating method that can accurately and quickly measure the thermophysical properties of minerals and rocks under high temperature and high pressure. Summary of the Invention

[0003] The present invention provides a device and method for synchronously measuring the thermal conductivity and thermal diffusivity of mineral rocks under extreme conditions, which solves the problems in the prior art of being unable to accurately measure κ and D synchronously, having weak anti-interference ability and low data accuracy.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A device for synchronously measuring thermal conductivity and thermal diffusivity of mineral rocks under extreme conditions, comprising: a power supply module, a pulse heating module, and a data acquisition module;

[0006] Wherein, the power supply module is used to supply power to the pulse heating module and the data acquisition module;

[0007] The pulse heating module is used to perform pulse heating on the sample;

[0008] The data acquisition module is used to collect voltage signals from the pulse heating module and the external thermocouple.

[0009] Preferably, the pulse heating module includes two solid-state relays and corresponding trigger circuits, five 1kΩ non-inductive precision resistors connected in parallel with the planar heat source, and one 2Ω non-inductive precision resistor connected in series with the planar heat source.

[0010] Preferably, the data acquisition module includes one 24-bit dynamic data acquisition card and two TB26D acquisition card connection terminals;

[0011] Among them, one terminal uses three groups of analog input channels to collect pulse voltage, loop current and sample temperature signals respectively; the three groups of channels are scheduled by a unified clock and collect three groups of signals simultaneously to ensure signal synchronization; all three groups of channels have built-in 24-bit ADC (analog-to-digital converter) with a resolution of <100nV;

[0012] The other terminal uses a set of digital output channels to send trigger signals to the pulse circuit.

[0013] The present invention also provides a method for synchronously measuring the thermal conductivity and thermal diffusivity of mineral rocks under extreme conditions. The method is implemented by the aforementioned device and comprises:

[0014] Assembling the rock samples to be measured;

[0015] Connect thermocouples, planar heat sources, and pulse power supply lines to the measurement device via twisted-pair copper wires;

[0016] Apply target pressure via a multi-faceted anvil large press;

[0017] If the sample needs to be heated, use direct current to heat the TiB2 main heater;

[0018] Preset file storage path, test data file name, sample thickness, pulse detection threshold, cable resistance R 线缆 , cold end temperature, sample thickness, sample density, sampling rate, sampling period, pulse heating voltage, pulse width, circuit direction, sampling times;

[0019] Pulse heating is performed on the sample, and the electromotive force change of the thermocouple is converted into temperature change data;

[0020] Synchronously collect the voltage signal of the thermocouple circuit, the voltage signal of the 2Ω standard resistor, and the voltage signal at both ends of the voltage divider resistor R1, combined with the pre-measured cable resistance R 线缆 , calculate the resistance R of a plane heat source at high temperature and high pressure 平面热源 and the corresponding power;

[0021] The relationship between temperature change and time is mathematically fitted to obtain the thermal conductivity and thermal diffusivity of the sample.

[0022] Preferably, the method for assembling the rock samples to be measured includes:

[0023] Three thin disc samples of equal thickness were placed in the middle of the pressure transmission medium. A flat heat source of the same size as the sample was placed in the middle of two of the samples, and a thermocouple was placed between the centers of the other two samples. Ni rods were placed at both ends of the samples, and the samples were surrounded by insulating ZrO2 material.

[0024] Preferably, calculate the resistance R of a planar heat source at high temperature and high pressure 平面热源 And the corresponding power methods include:

[0025] P plane heat source = I 2 (R total-R cable);

[0026] Where I is the plane heat source loop current, R 总 is the total line resistance, P 平面热源 is the power of a planar heat source under high temperature and high pressure.

[0027] Preferably, the method of mathematically fitting the relationship between temperature change and time to obtain the thermal conductivity and thermal diffusivity of the sample includes:

[0028]

[0029] Where ΔT is the temperature change, x represents the position of the flat thermocouple, which is 2 / 3d, d represents the total thickness of the three sample discs, t represents the time interval between pulse heating and the start of measurement, τ represents the pulse heating duration, P represents the pulse heating power, S represents the area of ​​the planar heat source, D represents the thermal diffusivity, and κ represents the thermal conductivity.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. Synchronous measurement: Using multi-channel acquisition card and software control, synchronously collect thermocouple electromotive force signal, pulse voltage signal, standard resistor voltage signal, and obtain κ, D and C synchronously in a single experiment. p , efficiency increased by more than 90%.

[0032] 2. High-precision anti-interference: By controlling the circuit with two solid-state relays, multiple measurements of the forward and reverse circuits can be achieved, eliminating the inductance in the planar heat source circuit and effectively eliminating 50 Hz mains frequency interference. The background noise is ≤ 4 μV, and the temperature resolution is better than 0.1 K. This avoids the problem that traditional methods cannot accurately measure the power of planar heat sources.

[0033] 3. High-pressure compatibility: Adaptable to the large multi-faceted anvil press platform, it can measure under extreme conditions of high temperature and high pressure.

[0034] 4. Intelligent control: The software written in LabVIEW is used to automatically complete data acquisition, filtering, fitting and storage, reducing human errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 This is a schematic diagram of an assembly diagram for measuring the thermophysical parameters of a sample using a pulse heating method according to an embodiment of the present invention;

[0037] Figure 2 Figure 1 is a diagram of a rock and mineral thermophysical property measuring instrument based on a pulse heating method according to an embodiment of the present invention, wherein (a) is a front view of the internal components; (b) is a back view of the internal components; (c) is a front view;

[0038] Figure 3 This is a planar heat source circuit diagram in the internal circuit diagram of an embodiment of the present invention;

[0039] Figure 4 This is a power supply circuit diagram in the internal circuit diagram of an embodiment of the present invention;

[0040] Figure 5 This is a thermocouple circuit diagram in the internal circuit diagram of an embodiment of the present invention.

[0041] In the figure: 101-1: TB26D terminal board 1; 101-2: TB26D terminal board 2; 102: 2Ω standard resistor; 103: Five 1000Ω voltage-dividing resistors; 104-1: Ultra-low latency solid-state relay 1; 104-2: Ultra-low latency solid-state relay 2; 105: Wire trough; 106: Terminal block; 107: Epoxy insulation board; 201: 24-bit multi-channel acquisition card; 202: AC-DC linear power supply; 203: Power battery pack; 301: Built-in DC power supply selection switch; 302: Thermocouple interface; 303: Planar heat source interface; 304: External DC power supply interface; 305: Power switch; 306: USB data transmission interface. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] Principle of pulse heating method:

[0046] like Figure 1 As shown, three thin cylindrical samples of equal thickness (e.g., olivine samples, each with a diameter of 3mm and a thickness of 0.2mm) are placed in the middle of a pressure-transmitting medium. A planar heat source (e.g., a molybdenum planar heat source, typically 0.02mm thick) of equal diameter is placed in the middle of two of the samples, while a square ultra-thin K-type thermocouple (1mm wide, 0.05mm thick) is placed between the centers of the other two samples. Ni rods (3mm diameter, 1.1mm height) are placed at both ends of the samples, and the samples are surrounded by insulating ZrO2 material. This device can provide a nearly one-dimensional homogeneous heat conduction model for the samples. Connection relationship with the thermal conductivity meter: 1) Use a twisted shielded pair of cables to connect the two rectangular wings of the planar heat source to the 303 planar heat source interface on the front panel of the thermal conductivity meter; 2) Use a twisted shielded pair of cables to connect the thermocouple to the 302 thermocouple interface on the front panel of the thermal conductivity meter. During the measurement, a planar heat source is loaded with a DC current of a fixed pulse width (e.g., 10ms). The heat generated by the heat conduction through the overlying sample causes the potential fluctuation of the thermocouple. The thermocouple's electromotive force signal is converted into temperature, and then the relationship between the temperature change and time is mathematically fitted to obtain the thermal conductivity and thermal diffusivity of the sample. During the stage where the heat source continuously releases energy (0≤t≤τ), the temperature response is given by the Green's function solution of the inhomogeneous heat conduction equation. For the Dirichlet boundary condition (fixed temperature of the nickel rod contact surface), the relationship between the temperature fluctuation ΔT at x and time satisfies:

[0047]

[0048] After the heat source is turned off (t>τ), the temperature field is given by the Green's function solution of the homogeneous heat conduction equation, with the initial condition being the temperature distribution at the end of the heating phase. The temperature fluctuation ΔT at x varies with time as follows:

[0049]

[0050] Parameters A and B are defined as follows:

[0051]

[0052] Where x represents the position of the flat thermocouple (2 / 3d), d represents the total thickness of the three sample discs (m), t represents the time interval between pulse heating and the start of measurement (s), τ represents the pulse heating time (s), P represents the pulse heating power (W), and S represents the area of ​​the planar heat source (m 2 ), D represents the thermal diffusivity (mm 2 / s), and κ represents thermal conductivity (W / mK). Because pulse heating often causes electromagnetic induction, the thermocouple will experience large electromotive force interference, which affects data fitting. Therefore, we usually only use data after pulse heating for fitting. That is, we use formulas (2) and (3) to fit the thermal disturbance signal. When n is set to 15, sufficiently accurate thermal conductivity and thermal diffusivity can be obtained.

[0053] The instrument of the present invention is developed based on the above-mentioned "pulse heating method principle". The present invention discloses a device for synchronously measuring the thermal conductivity and thermal diffusivity of mineral rocks under extreme conditions. The device includes: a power supply module, a pulse heating module and a data acquisition module;

[0054] Wherein, the power supply module is used to supply power to the pulse heating module and the data acquisition module;

[0055] Pulse heating module, used for pulse heating of samples;

[0056] The data acquisition module is used to collect voltage signals from the pulse heating module and the external thermocouple.

[0057] Among them, 1) the acquisition card and two solid-state relays are powered by a 15W DC linear regulated power supply ( Figure 2 b, 202); 2) The pulse heating module includes two solid-state relays and their trigger circuits ( Figure 3 When the trigger circuit is high, the MOSFET is turned on, connecting the planar heat source to the pulse power circuit. The on / off time of the MOSFET is less than 50μs, with a typical value of 27μs). It consists of 5 1kΩ non-inductive precision resistors and 1 2Ω non-inductive precision resistor. The power supply of the pulse heating module is divided into built-in power supply and external power supply, which are switched by a 4-speed conversion switch. The built-in power supply ( Figure 2 b, 203) consists of three 5000mA, 4V power batteries connected in series, with three output terminals (4V, 8V, 12V), providing a maximum heating pulse power supply of 12V, 7A. The external power supply is configured by the user. This instrument only provides a connection interface; 3) The data acquisition module includes a 24-bit dynamic data acquisition card ( Figure 2 b, 201), 2 TB26D acquisition card terminals ( Figure 2 a, 101-1, 101-2). Terminal 101-2 uses three analog input channels to collect pulse voltage, loop current, and sample temperature signals respectively. The three channels are scheduled by a unified clock and collect three sets of signals simultaneously to ensure signal synchronization; all three channels have built-in 24-bit ADCs (analog-to-digital converters) with a resolution of <100nV. Terminal 101-1 uses a digital output channel to send trigger signals to the pulse circuit. The specific structure of the device is as follows Figure 2 As shown, the internal circuit connections of the instrument are as follows Figure 3 、 Figure 4 、 Figure 5 The following is a description of each component:

[0058] 1) TB26D acquisition card terminal blocks (101-1, 101-2): 101-2 is used to acquire voltage signals from thermocouple electromotive force, 2Ω standard resistor divider, and 1kΩ resistor divider; 101-1 is used to send trigger signals to the pulse circuit.

[0059] 2) 2 ohm standard resistor (102): as a standard resistor, used to calculate the current of the planar heat source circuit. This sampling resistor also plays a role in current limiting to prevent the planar heat source from short-circuiting and causing the acquisition card to overload.

[0060] 3) Five 1k voltage divider resistors (103): used to calculate the total line voltage;

[0061] 4) Fast response solid-state relay (104-1, 104-2): controls pulse heating (delay time ≤ 1 μs) and pulse current direction;

[0062] 5) Wire duct (105): used for regular wiring;

[0063] 6) Terminal blocks (106): fast and safe wiring, reducing contact resistance;

[0064] 7) 24-bit high-precision acquisition card (201): supports 1-250k / s sampling rate, sub-microsecond time synchronization, multi-channel synchronous voltage data acquisition and control pulse circuit;

[0065] 8) AC to DC linear power supply (202): converts the mains power to 15V DC power to power the acquisition card and solid-state relay, which can effectively reduce the mains power frequency interference and reduce the background noise to the microvolt level;

[0066] 9) Power battery pack (203): power lithium battery (5000mA, 4V), providing 4V, 8V or 12V DC power to the planar heat source;

[0067] 10) Built-in DC power supply selection switch (301): 4-speed rotary switch, controls the built-in DC power supply voltage;

[0068] 11) Thermocouple interface (302): 3-core aviation plug, external thermocouple circuit;

[0069] 12) Planar heat source interface (303): 4-core aviation plug, externally connected to the planar heat source circuit;

[0070] 13) Pulse power interface (304): 2-core aviation plug, external DC power supply, powering the planar heat source;

[0071] 14) Power switch (305): controls the opening and closing of the entire circuit;

[0072] 15) USB interface (306): connected to an external computer for data transmission.

[0073] Example 2

[0074] The present invention provides a method for synchronously measuring the thermal conductivity and thermal diffusivity of mineral rocks under extreme conditions. The method is implemented using the apparatus described in Example 1 and includes:

[0075] 1) Sample preparation: First, the rock sample to be measured is placed in Figure 1 In the assembly diagram shown;

[0076] 2) Connect the thermocouple, planar heat source, and pulse power supply line (not required when using the built-in power supply) to the thermal conductivity meter (in this case) through twisted-pair shielded wires. For the specific wiring diagram, refer to Figure 3 、 Figure 4 、 Figure 5 ;

[0077] 3) High-pressure loading: applying the target pressure (e.g., 1 GPa) through a multi-faceted anvil press;

[0078] 4) High temperature loading: If the sample needs to be heated, use the linear DC power supply of the multi-faceted anvil press to heat the sample.

[0079] Heating by TiB2 main heater (the heating temperature does not exceed the limit temperature of the TiB2 heater, such as about 1900°C under 1GPa);

[0080] 5) Set the file storage path, test data file name, sample thickness, pulse detection threshold, cable resistance R 线缆 (Before applying pressure, use a 6.5-digit meter to measure the resistance of the connecting wire), cold junction temperature (corrected temperature), sample thickness, sample density, sampling rate, sampling period, pulse heating voltage, pulse width, circuit direction, and number of sampling times;

[0081] 6) Data acquisition and calculation method. The DC power supply pulse heats the sample. The thermocouple generates an electromotive force change due to the pulse heating of the planar heat source. The data acquisition module converts it into temperature data (converted according to the thermocouple graduation table of the national standard of the People's Republic of China). The 24-bit acquisition card synchronously collects the voltage signal of the thermocouple circuit (calculate the sample temperature) and the voltage signal of the 2Ω standard resistor (U 2Ω , used to calculate the plane heat source loop current I, ), the voltage signal across the voltage divider resistor R1 (U1, used to calculate the total voltage U of the planar heat source circuit 总 =5U1+U 2Ω and the total line resistance ). Combined with the pre-measured cable resistance R 线缆 (not in the sample chamber, so its value remains unchanged under high temperature and high pressure conditions), the resistance R of the plane heat source under high temperature and high pressure can be accurately calculated 平面热源 =R 总 -R 线缆 And its power P plane heat source = I 2 (R-to-R cable).

[0082] 7) After the acquisition is completed, the relationship between sample temperature (raw data) and time, the relationship between sample filter temperature and time, the relationship between pulse voltage and time, the relationship between current and time of pulse heating circuit, and the relationship between plane heat source resistance and time will be automatically projected. In addition to the above graphs, the instrument will also provide the actual pulse width, pulse voltage, loop current, sample resistance (i.e. plane heat source resistance), pulse power, and background temperature. Note: The above data are all from 2 n The average value of the measurements is calculated.

[0083] 8) Data Fitting. Two methods: 1) Automatic Fitting: Enter the time coordinates for the start and end points of the fit. The system automatically fits the spectrum between the two points according to Formulas 1 and 2, and calculates the thermal conductivity, thermal diffusivity, and specific heat capacity. 2) Manual Fitting: Use the mouse to select the start and end points of the fit in the sample temperature graph. The system will fit the temperature spectrum and calculate the thermal conductivity, thermal diffusivity, specific heat capacity, and fitting error.

[0084] Key points of the present invention: 1. A method for effectively suppressing electromagnetic induction in a circuit by utilizing the forward and reverse control of a planar heat source circuit;

[0085] 2. A method for calculating the power of a planar heat source under high temperature and high pressure using a series standard resistor solves the problem that traditional methods cannot accurately measure the resistance and power of a planar heat source;

[0086] 3. A method for efficiently collecting and accurately calculating the thermal conductivity, thermal diffusivity and specific heat capacity of the sample under test using a 24-bit acquisition card and self-written software.

[0087] Example 3

[0088] This example takes the test of a San-Carlos olivine single crystal sample at 1-9 GPa and 300-900 K as an example:

[0089] The San-Carlos olivine single crystal sample was processed into a cylinder with a diameter of 3 mm and a thickness of 0.5 mm. It was loaded into a 6-8 multi-faceted anvil press and pressurized to 1 GPa. The temperature was then raised from room temperature to 400K, 500K, 600K, 700K, 800K, and 900K. The thermophysical parameters were measured at each temperature. The software measurement interface is as follows: Figure 1After all measurements at 1 GPa are completed, the temperature is lowered to room temperature, the pressure is raised to 3 GPa, and the above heating and measuring process is repeated; the pressure is raised again (at intervals of 2 GPa) and the above steps are repeated until all measurements at 9 GPa are completed. The specific measurement process at a specific pressure and temperature is as follows:

[0090] 1. Experimental parameter settings: as shown in Table 1:

[0091] Table 1

[0092]

[0093] 2. Data Collection:

[0094] The collected data include: the divided voltage of the 1kΩ resistor, the electromotive force of the thermocouple, and the divided voltage of the 2Ω resistor within the collection time t.

[0095] 3. Data Visualization:

[0096] The system will automatically generate a graph showing the relationship between sample temperature (raw data) and time, a graph showing the relationship between sample filter temperature and time, a graph showing the relationship between pulse voltage and time, a graph showing the relationship between current and time of the pulse heating circuit, and a graph showing the relationship between plane heat source resistance and time.

[0097] 4. Data fitting and calculation results:

[0098] Automatic fitting: Input the time coordinates of the starting and ending points of the fitting, and use the difference method to fit the spectrum between the starting and ending points according to formulas (2) and (3), and calculate the thermal conductivity, thermal diffusivity and specific heat capacity.

[0099] Fitting range: 3.471ms-12.477ms.

[0100] Fitting data: A = 25.484 ± 0.074.

[0101] B=50.155±0.118.

[0102] R-square = 0.985.

[0103] κ: 5.35W / (m·K).

[0104] D: 1.95mm 2 / s.

[0105] c p :0.816J / (kg·K).

[0106] 5. Comparison of experimental data and reference values: as shown in Table 2:

[0107] Table 2

[0108]

[0109] The experimental pressure in this embodiment is 1 GPa, which is higher than the data in the reference, but the influence of pressure is very small, and our experimental data is basically consistent with the reference.

[0110] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A device for synchronously measuring thermal conductivity and thermal diffusivity of mineral rocks under extreme conditions, characterized by: The device includes: a power supply module, a pulse heating module and a data acquisition module; Wherein, the power supply module is used to supply power to the pulse heating module and the data acquisition module; The pulse heating module is used to perform pulse heating on the sample; The data acquisition module is used to collect voltage signals from the pulse heating module and the external thermocouple.

2. The device according to claim 1, characterized in that The pulse heating module consists of two solid-state relays and corresponding trigger circuits, five 1kΩ non-inductive precision resistors connected in parallel with the planar heat source, and one 2Ω non-inductive precision resistor connected in series with the planar heat source.

3. The device according to claim 1, characterized in that The data acquisition module includes one 24-bit dynamic data acquisition card and two TB26D acquisition card wiring terminals; Among them, one terminal uses three groups of analog input channels to collect pulse voltage, loop current and sample temperature signals respectively; the three groups of channels are scheduled by a unified clock and collect three groups of signals simultaneously to ensure signal synchronization; all three groups of channels have built-in 24-bit ADC (analog-to-digital converter) with a resolution of <100nV; The other terminal uses a set of digital output channels to send trigger signals to the pulse circuit.

4. A method for synchronously measuring the thermal conductivity and thermal diffusivity of mineral rocks under extreme conditions, the method being implemented by the device according to any one of claims 1 to 3, characterized in that: The method comprises: Assembling the rock samples to be measured; Connect thermocouples, planar heat sources, and pulse power supply lines to the measurement device via twisted-pair copper wires; Apply target pressure via a multi-faceted anvil large press; If the sample needs to be heated, use direct current to heat the TiB2 main heater; Preset file storage path, test data file name, sample thickness, pulse detection threshold, cable resistance R 线缆 , cold end temperature, sample thickness, sample density, sampling rate, sampling period, pulse heating voltage, pulse width, circuit direction, sampling times; Pulse heating is performed on the sample, and the electromotive force change of the thermocouple is converted into temperature change data; Synchronously collect the voltage signal of the thermocouple circuit, the voltage signal of the 2Ω standard resistor, and the voltage signal at both ends of the voltage divider resistor R1, combined with the pre-measured cable resistance R 线缆 , calculate the resistance R of a plane heat source at high temperature and high pressure 平面热源 and the corresponding power; The relationship between temperature change and time is mathematically fitted to obtain the thermal conductivity and thermal diffusivity of the sample.

5. The method according to claim 4, characterized in that Methods for assembling the rock samples to be measured include: Three thin disc samples of equal thickness were placed in the middle of the pressure transmission medium. A flat heat source of the same size as the sample was placed in the middle of two of the samples, and a thermocouple was placed between the centers of the other two samples. Ni rods were placed at both ends of the samples, and the samples were surrounded by insulating ZrO2 material.

6. The method according to claim 4, characterized in that Calculate the resistance R of a planar heat source at high temperature and high pressure 平面热源 And the corresponding power methods include: P plane heat source = I 2 (R total-R cable); Where I is the plane heat source loop current, R 总 is the total line resistance, P 平面热源 is the power of a planar heat source under high temperature and high pressure.

7. The method according to claim 4, characterized in that Methods for mathematically fitting the relationship between temperature change and time to obtain the thermal conductivity and thermal diffusivity of the sample include: Where ΔT is the temperature change, x represents the position of the flat thermocouple, which is 2 / 3d, d represents the total thickness of the three sample discs, t represents the time interval between pulse heating and the start of measurement, τ represents the pulse heating duration, P represents the pulse heating power, S represents the area of ​​the planar heat source, D represents the thermal diffusivity, and κ represents the thermal conductivity.

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