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CN-119666920-B - Dynamic measurement device and measurement method for heat conductivity coefficient under high temperature condition

CN119666920BCN 119666920 BCN119666920 BCN 119666920BCN-119666920-B

Abstract

The dynamic measurement device and the measurement method for the heat conductivity coefficient under the high-temperature condition are provided. The dynamic measurement device for the heat conductivity coefficient under the high temperature condition comprises a furnace body, a heat preservation layer, a sample sleeve assembly, a heating assembly and a temperature measuring probe, wherein the heat preservation layer is arranged in the furnace body, the sample sleeve assembly is used for installing a sample disc and forming a uniform temperature surface, the sample sleeve assembly comprises a heat protection plate, the heat protection plate is used for being installed at one axial end of the sample disc, the heating assembly comprises heating units positioned in the heat preservation layer, the two ends of the sample sleeve assembly are respectively provided with the heating units, the heat protection plate is positioned between the sample disc and one of the heating units, the two heating assemblies are respectively independently controlled and have adjustable power, the temperature measuring probe is positioned at the two ends of the furnace body, and the heat preservation layer and the heating assembly are provided with light path channels avoiding the detection path of the temperature measuring probe. The heating assemblies at the two ends of the sample sleeve assembly can provide enough heating power, and are beneficial to forming a uniform temperature field. While a heat shield plate at only one end facilitates temperature rise control of only a single shaft end.

Inventors

  • SUN YANFEI
  • WU YONGYONG
  • YANG XINGTUAN
  • REN CHENG

Assignees

  • 清华大学

Dates

Publication Date
20260505
Application Date
20241216

Claims (8)

  1. 1. A dynamic measurement device for thermal conductivity under high temperature conditions, comprising: A furnace body (3); The heat preservation layer (4) is positioned in the furnace body (3); a sample sleeve assembly (6) for mounting a sample tray (63), the sample sleeve assembly (6) comprising a heat shield plate (64), the heat shield plate (64) for mounting to an axial end of the sample tray (63); The heating assembly (5), the heating assembly (5) comprises heating units positioned in the heat insulation layer (4), the heating units are arranged at two ends of the sample sleeve assembly (6), the heat protection plate (64) is positioned between the sample plate (63) and one of the heating units, and the two heating assemblies (5) are independently controlled and have adjustable power; the temperature measuring probe is positioned at two ends of the furnace body (3), the heat insulation layer (4) and the heating component (5) are provided with light path channels avoiding the detection path of the temperature measuring probe, The sample sleeve assembly (6) comprises a sleeve for wrapping the sample tray (63) and the heat shield plate (64), The sample sleeve assembly (6) further comprises emissivity pipes arranged at two ends of the sample disc (63), the opposite surfaces of the two emissivity pipes are in a blocking state, the opposite surfaces of the two emissivity pipes are in an opening state, and the emissivity pipes penetrate through the sleeve and the heat protection plate (64).
  2. 2. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 1, wherein said sample sleeve assembly (6) comprises graphite paper (65) for sandwiching between said sample tray (63) and said heat shield plate (64).
  3. 3. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 1, wherein the material of the heat insulation layer (4) comprises carbon fiber felt and the material of the sleeve comprises graphite; the furnace body (3) is vacuumized or filled with inert gas.
  4. 4. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 2, wherein the sample tray (63), the heat shield plate (64), the graphite paper (65), the emissivity tube are coaxially arranged; The furnace body (3), the heat preservation layer (4), the heating unit, the sample sleeve assembly (6) and the temperature measuring probe are coaxially arranged; The furnace body (3) comprises furnace body units in butt joint with each other in an opening mode, and the heat preservation layer (4) comprises heat preservation layer units in butt joint with each other in an opening mode.
  5. 5. The dynamic measurement device for the heat conductivity coefficient under the high temperature condition according to claim 1, wherein the temperature measurement probe is a non-contact infrared temperature measurement probe (1), the non-contact infrared temperature measurement probe (1) is positioned outside the furnace body (3), and the non-contact infrared temperature measurement probe (1) is connected with the furnace body (3) through a sight glass (2).
  6. 6. The dynamic measurement device for thermal conductivity under high temperature conditions according to claim 1, wherein the heating unit is an electric heater (51), the electric heater (51) is in a shape of a cake, and the electric heater (51) comprises heating wires which are arranged in a meandering manner; graphite electrodes (52) are connected to two ends of the heating wire, water-cooled copper electrodes (53) are connected to two opposite ends of the graphite electrodes (52), and the water-cooled copper electrodes (53) penetrate through the inner wall and the outer wall of the furnace body (3).
  7. 7. The dynamic measurement device for thermal conductivity under high temperature according to claim 4, wherein the furnace body unit is provided with flange rings (36) at the butt joint parts of the openings; the butt joint of the openings of the heat preservation units is provided with annular concave-convex structures (43) which are mutually matched; The heat preservation unit comprises a containing cavity (41) in butt joint with each other in an opening mode, the sample sleeve assembly (6) and the heating unit are located in the containing cavity (41), a through channel (42) is communicated with the bottom surface of the containing cavity (41), the inner diameter of the through channel (42) is smaller than that of the containing cavity (41), and the light path channel comprises the through channel (42).
  8. 8. A method for dynamically measuring thermal conductivity under high temperature conditions, characterized in that the device for dynamically measuring thermal conductivity under high temperature conditions according to any one of claims 1 to 7 is used, the method comprising: Step S1, utilizing the heating assemblies (5) arranged at two ends of the sample sleeve assembly (6) to integrally heat the sample tray (63) and the heat protection plate (64); S2, when the heat preservation layer (4) is heated to a specified uniform temperature, the power of the heating component (5) at one end adjacent to the heat protection plate (64) is kept unchanged, and the power of the heating component (5) at the other end is increased and the temperature is continuously increased; And S3, using the temperature measuring probe to non-contact measure the sample disc (63) serving as the measured material, and measuring dynamic temperature rise curves at the central points of the two ends of the sample disc (63) to obtain the thermal diffusivity and the thermal conductivity of the measured material.

Description

Dynamic measurement device and measurement method for heat conductivity coefficient under high temperature condition Technical Field The application relates to the field of heat conductivity coefficient measurement, in particular to a dynamic measurement device and a measurement method for heat conductivity coefficient under high temperature. Background The heat conductivity coefficient is a key thermophysical property of a material, and is a basic and important design input parameter for the fields of material selection, heat transfer design, temperature field analysis and calculation and the like. The high-temperature resistant material is widely applied to various tip fields such as nuclear energy utilization, aerospace, metallurgy and the like, and the material is required to be used for isolating ultra-high temperature gas when a tip space rocket and a space shuttle reenter the atmosphere, so that the situation that a bin shell is disintegrated and the surface layer heat insulation tile falls off and fails when the space shuttle is reentered to the atmosphere is avoided. The application fields often need to select high-temperature resistant materials, heat-insulating materials and the like, and conduct heat transfer design. The heat conductivity coefficient of the high-temperature-resistant heat insulation material is important basic data of the work, so that the convenient and accurate measurement of the heat conductivity coefficient of the material at high temperature is also an urgent technical requirement. In general, the thermal conductivity of a substance is a function of temperature rather than a constant, and therefore it is often desirable to measure the thermal conductivity of a material at different temperatures. The measuring means known by the inventor is generally a static measuring method according to the law of steady-state heat conduction, namely, a measured material is processed into a workpiece with a certain regular shape, one side of the workpiece is heated, the other side of the workpiece is cooled, and after the temperature is stabilized, the heat conductivity coefficient of the material is obtained through calculation of power, temperature difference and workpiece size. There is also a dynamic thermal conductivity measurement method, for example, using laser pulses to heat a local part of a material in a short time, and then observing the time-dependent change of a temperature field, so as to estimate the thermal diffusivity and thermal conductivity of the material. The static method measurement heat conductivity coefficient technology known by the inventor is low in measurement accuracy under high temperature condition, because the static method is used for measuring the heat conductivity coefficient, the heat power conducted by the measured material is inevitably measured, however, because the heat dissipation problem cannot ensure that all heating power passes through the measured material, the heat dissipated at the heat conduction boundary cannot be accurately measured, and the heat transfer path is not always along the heat flow density direction, so that the measurement accuracy of the static method is low. In addition, the static method is also difficult to be applied to the high temperature field, because in order to prevent the material from being oxidized under the high temperature condition, the test needs to be performed under the vacuum or inert gas protection closed condition, and the heat dissipation condition of the cold end of the tested material is difficult to be built. Under the high temperature condition of above 1200 ℃, the heat dissipation loss of the static method is larger, so that the measured thermal power is inaccurate in measurement, and the measurement accuracy is reduced. The technology for measuring the heat conductivity coefficient by using the dynamic method of laser heating known by the inventor is generally not used for testing the heat insulation material because the heat insulation material is in a porous medium form and has low heat diffusion coefficient, and the heat generated by laser pulse cannot be completely absorbed on the surface layer, so that effective pulse heat diffusion cannot be formed inside the heat insulation material. In addition, as a thermal conductivity meter for measuring thermal conductivity. A relatively common thermal conductivity meter is the hot wire method thermal conductivity meter. The heat conduction instrument by the hot wire method is a heat conduction instrument that embeds a hot wire in a sample, generates heat by applying a constant current, and measures the temperature of the hot wire and related parameters to calculate the heat conductivity. The method is suitable for various materials, and has good measurement effect especially for anisotropic materials and materials with low heat conductivity coefficient. The heat conduction instrument is always provided with a constant-current heat source. For exampl