CN112630261A - Measuring device and measuring method for multiple thermophysical parameters of material - Google Patents
Measuring device and measuring method for multiple thermophysical parameters of material Download PDFInfo
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- CN112630261A CN112630261A CN202011460676.0A CN202011460676A CN112630261A CN 112630261 A CN112630261 A CN 112630261A CN 202011460676 A CN202011460676 A CN 202011460676A CN 112630261 A CN112630261 A CN 112630261A
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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
Abstract
The invention provides a device and a method for measuring multiple thermophysical parameters of a material, and the device comprises a fixed frame, a laser generating device, an infrared thermal imaging device, a convex lens, a temperature measuring device and a data receiving and processing device, wherein the laser generating device outputs a laser signal to heat the measured material, the convex lens focuses laser on the material to be measured to generate an obvious temperature rise signal, the infrared thermal imaging device acquires the temperature rise signal, the data receiving and processing device acquires a temperature signal of the surface of the material to be measured, which is measured by the infrared thermal imaging device, and a temperature signal obtained by measuring a thermocouple, then the surface emissivity of a sample at different temperatures can be obtained by calculation, experimental correction is carried out, and finally the corrected temperature information is fitted by a computer numerical value to obtain the thermophysical parameters of the measured. The method can measure the multi-thermophysical property parameters of the material under the condition of not damaging the surface structure and the surface characteristics of the material, and eliminate the measurement errors caused by contact thermal resistance and sample surface damage due to contact.
Description
Technical Field
The invention belongs to the technical field of thermophysical property measurement, and particularly relates to a device and a method for measuring multiple thermophysical property parameters of a material.
Background
Thermal diffusion coefficient, thermal conductivity, specific heat capacity, surface emissivity and the like are important physical parameters of various materials, and the material has a wide application background in the field of heat transfer engineering. However, the thermal property parameters of various materials are mainly determined by experiments, and how to quickly, accurately and conveniently measure the thermal property of various materials becomes very important. In the conventional thermophysical property measurement techniques, a physical model according to a measurement method is roughly classified into a steady-state measurement method and a transient-state measurement method. In the steady state method, the sample needs to be uniformly heated or cooled to a thermal steady state before thermophysical parameter measurement is performed. Its advantage is simple mathematical model, but it takes longer time for the sample to reach thermal steady state in measurement. Meanwhile, the corresponding measuring device of the transient measuring method is complex, and the sample needs to be processed into a specified shape, so that the application of the transient measuring method in the industry is limited. In addition, most of the current experimental measurements are single parameters or thermophysical parameters at a certain temperature. It only represents one physical property of the material at a certain temperature, and cannot reflect the actual thermal physical properties and change trend of the material at different temperatures.
Infrared imaging uses optoelectronic devices to detect and measure radiation and to correlate the radiation with surface temperature. A technique for receiving the radiant energy emitted by an object and thereby inferring its temperature. The infrared measurement of the temperature of an object requires knowing the surface emissivity of the object, but the surface emissivity also changes along with the change of the temperature of the material and the surface characteristics of the material, and real-time correction of the surface emissivity is needed.
Patent No. CN104215660A discloses a method and system for simultaneously measuring the thermal conductivity and thermal diffusivity of a solid material. The measuring device generates a constant-temperature water medium with a certain temperature by using a super constant-temperature water bath, a sample is placed into a sample box with the bottom being a brass plate and the upper surface and the side surfaces being sealed by heat insulation materials, the bottom of the sample box is contacted with the constant-temperature water medium to form a one-dimensional unsteady heat transfer process under a constant-temperature boundary, and then the thermal diffusivity, the specific heat capacity and the heat conductivity coefficient of a measured material are obtained by using a parameter estimation method. However, the device is in a steady-state heat transfer model, the stabilization time is long, and the measurement time is long. Patent No. CN107907565A discloses a method for measuring thermophysical parameters of a solid material based on a laser spot heat source. The device is directly based on a constant power boundary one-dimensional unsteady state heat transfer model, and the thermal conductivity and thermal diffusivity of the solid material are measured by using a parameter estimation method, so that errors caused by over simplification of a mathematical model are avoided. However, the measuring apparatus requires polishing of the surface of the measuring material, and has certain requirements for the measuring environment and the measuring material. The method uses a plurality of thermocouples to measure the back temperature, cannot be suitable for occasions needing single-side measurement, has more temperature measuring points, needs a plurality of groups of temperature measuring elements, has higher energy consumption, and has the problems of poor contact and the like. In addition, the device has complex algorithm, cannot carry out real-time measurement, and must sample laboratory measurement, thereby limiting the application of the device in industry.
Disclosure of Invention
The invention aims to provide the measuring device for the multi-thermophysical parameters of the material aiming at the defects in the prior art, the measuring device is simple and convenient to operate, and can carry out single-side nondestructive measurement on the measured material and the measuring result is accurate.
In order to solve the technical problems, the invention adopts the following technical scheme:
a measuring device for multi-thermal parameters of a material comprises a fixed frame, a laser generating device, an infrared thermal imaging device, a convex lens, a temperature measuring device and a data receiving and processing device; wherein the content of the first and second substances,
the fixed frame is used for supporting the laser generating device and the infrared thermal imaging device;
the laser generating device is used for generating laser for heating the material to be detected, and comprises a laser controller and a laser electrically connected with the laser controller, and the laser is movably arranged on the fixed frame;
the thermal infrared imager device is used for acquiring temperature information of the surface of a material to be measured, and comprises a thermal infrared imager host and a thermal infrared imager probe electrically connected with the thermal infrared imager host, wherein the thermal infrared imager probe is movably arranged on the fixed frame;
the convex lens is used for generating a laser spot with a proper size, the convex lens is movably arranged on the fixed frame, and the laser, the convex lens and the material to be measured are on the same light path during measurement;
the temperature measuring device is used for measuring the temperature of the material to be measured and is electrically connected with the material to be measured; and
and the data receiving and processing device is used for receiving and processing corresponding information and is electrically connected with the thermal infrared imager host and the temperature measuring device.
Furthermore, the laser and the thermal infrared imager probe are respectively arranged on the fixed frame through a shifter.
Further, the adjustment accuracy of the displacer is 10 micrometers.
Furthermore, the shifter comprises a first base fixed on the fixed frame, a first guide rail fixed on the first base, a first screw rod rotatably arranged between the first guide rails, and a first slider connected with the first screw rod through threads and in sliding connection with the first guide rail, and the laser and the thermal infrared imager are respectively arranged on the sliders corresponding to the shifter.
Further, convex lens passes through single-axis displacement device and sets up on the fixed frame, single-axis displacement device control convex lens removes on laser light path.
Further, unipolar displacement device includes motor and mechanical slip table, mechanical slip table is including fixing second base on the fixed frame, fix second guide rail on the second base, rotationally set up second lead screw between the second guide rail and with the second lead screw passes through threaded connection and sliding connection and is in second slider on the second guide rail, the second lead screw still with the drive shaft connection of motor, convex lens fixes on the second slider.
Further, the temperature measuring device is a thermocouple thermometer.
The invention also provides a measuring method of the measuring device for the multi-thermophysical property parameters of the material, which comprises the following steps:
s1: adjusting the positions of the laser and the convex lens on the fixed frame to enable the laser, the convex lens and the material to be detected to be on the same light path, adjusting the distance between the laser and the convex lens to enable the laser to be focused on the surface of the material to be detected to form a point heat source, and then adjusting the position of the thermal infrared imager probe to enable the material to be detected to be located at the focal length of the thermal infrared imager probe so that the thermal infrared imager host can obtain a clear infrared image;
s2: heating the material to be measured by using a laser, and under the heating of different powers, acquiring the temperature information of a certain point on the surface of the material to be measured as T by the thermal infrared imager host through the thermal infrared imager probe1While measuring the temperature at this point as T by means of a temperature measuring device2The thermal infrared imager and the temperature measuring device transmit the temperature information to the data receiving and processing device and give the real-time environmental temperature T of the data receiving and processing device3And calculating the surface emissivity epsilon of the sample at different temperatures according to the following formula:
ε＝[T1 4-T3 4]/[T2 4-T3 4]；
s3: the data receiving and processing device corrects the thermal infrared imager host in real time according to the acquired surface emissivity epsilon of the material to be measured at different temperatures, the corrected thermal infrared imager host is used for acquiring a sample initial temperature picture through a thermal infrared imager probe, and then the sample initial temperature picture is processed through the data receiving and processing device to obtain the initial temperature T of the measured material0；
S4: using the laser output to maintain a constant laser signal and recording the laser power value q applied at that time0The size of the spot diameter a on the material to be measured on which the laser is focused;
s5: while laser heating, the data receiving and processing device controls the thermal infrared imager host to acquire and record the instantaneous temperature signal T of the laser spot center, namely the highest temperature pointt；
S6: after the temperature distribution of the material to be measured reaches a stable state, finishing temperature acquisition to obtain a stable state temperature signal T∞And drawing a temperature-time curve; obtaining a transient temperature expression (1) and a steady-state temperature expression (2) of the highest point of the central temperature of the light spot according to the obtained temperature-time curve:
wherein, TtThe central temperature of the laser spot on the material to be measured at the moment T, T0Is the spot center temperature at time 0, i.e. the initial temperature, T∞The central temperature of the laser spot after the steady state is the steady state temperature, a is the diameter of the laser spot, q0Is the laser power;
s7: calculating the heat conductivity coefficient k, the thermal diffusion coefficient alpha and the heat capacity C of the molten salt of the material to be measured at different temperatures through the expressionpThe thermal conductivity k is obtained by the formula (2):
then, the thermal conductivity k is treated in the formula (1), and the thermal diffusion coefficient alpha is obtained through nonlinear curve fitting, so that the heat capacity is obtained:
further, during measurement, laser emitted by the laser is perpendicular to the surface of a sample to be measured, and an included angle between a light path of the thermal infrared imager probe and a laser light path is not more than 30 degrees.
Further, during measurement, the data receiving and processing device sets the data acquisition frequency of the thermal infrared imager host, controls the thermal infrared imager host to correct emissivity parameters of the surface of the material to be measured at different temperatures, obtains temperature information of the sample at each moment, and records transient temperature response and steady state temperature response.
Compared with the prior art, the invention has the beneficial effects that:
1) the device for measuring the multiple thermal parameters of the material can rapidly measure the multiple thermal properties of the measured material in a nondestructive mode, a laser outputs a constant laser signal to heat the measured material, a convex lens focuses laser on the measured material to generate an obvious temperature rise signal, a thermal infrared imager probe shoots a temperature distribution diagram of the measured material to obtain the temperature rise signal, a computer obtains a temperature signal of the surface of the measured material measured by a thermal infrared imager host and a temperature signal obtained by thermocouple measurement, then the surface emissivity of samples at different temperatures can be obtained through calculation, experiment correction is carried out, and finally the corrected temperature information is fitted through the computer numerical value to obtain the thermal property parameters of the measured material; the method can nondestructively measure the multi-thermophysical parameters of the material in real time, does not damage the surface structure and the surface characteristics of the material in the measuring process, eliminates the contact thermal resistance caused by contact and the measuring error caused by the damage of the surface of a sample, and can carry out on-site real-time measurement;
2) the measuring device designed by the invention is a single-side thermophysical property measuring device, the laser and the thermal infrared imager respectively heat and measure temperature signals on the same side and single side of a sample, and the multi-thermophysical property measurement and monitoring can be carried out on a measured sample under real-time working conditions;
3) the measuring device designed by the invention ensures that a proper temperature rise signal is generated under the condition of sample invariance by adjusting the laser power, and reduces the error of the measurement result caused by heat loss; setting environmental parameters such as environmental temperature, material properties and the like in the thermal infrared imager and surface emissivities at different temperatures, so that the measured temperature is corrected to set the data acquisition frequency of the thermal infrared imager host, the transient temperature and the final steady-state temperature of the sample at each moment are recorded, and the accuracy of the measurement result is ensured;
4) the measurement result is obtained by the cooperative fitting of transient response and steady-state response of the temperature rise of the material, the transient measurement method can quickly obtain thermophysical parameters, the steady-state measurement method can ensure the accuracy of the measurement result, and the cooperative measurement ensures high measurement precision and good reliability;
5) the device can be widely applied to fluid thermophysical property measurement, fluid is inhomogeneous due to the liquidity characteristic of the fluid, the device can measure the local thermophysical property of the material, and thermophysical property parameters of samples at different temperature levels can be researched by changing the temperature of the fluid.
Drawings
FIG. 1 is a schematic structural diagram of a measuring apparatus according to an embodiment of the present invention;
FIG. 2 is a flow chart of a measurement method according to an embodiment of the present invention;
FIG. 3 is a physical model diagram of a measurement method according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention.
As shown in FIG. 1, the invention provides a device for measuring multiple thermophysical parameters of a material, which comprises a fixed frame 9, a laser generating device, an infrared thermal imaging device, a convex lens 5, a temperature measuring device and a data receiving and processing device. In the present embodiment, the fixing frame 9 is a box-shaped housing with a cover on one side, and is used for supporting the laser generating device and the infrared thermal imaging device. In addition, the fixed frame 9 can also play an effective dustproof role, and the influence of dust and the like in the air on laser signals is reduced. The laser generating device is used for generating laser for heating the material to be tested 6, the laser generating device comprises a laser controller 1 arranged outside the fixed frame 9 and a laser 7 electrically connected with the laser controller 1, the laser 7 is an adjustable laser, the power of the laser 7 can be adjusted, the material to be tested 6 is ensured to have a proper temperature rise signal under the condition of invariance, and stable and constant laser power is output. The laser 7 is movably arranged on a longitudinal first inner side wall of the fixed frame 9. Specifically, the laser 7 is disposed on the first inner side wall by the first displacer 8, and the adjustment accuracy of the first displacer 8 is 10 μm. The first shifter 8 comprises a first base fixed on the fixed frame 9, a first guide rail fixed on the first base, a first screw rod rotatably arranged between the first guide rail, and a first slide block connected with the first screw rod through a thread and connected on the first guide rail in a sliding manner, and the laser 7 is fixedly arranged on the slide block. The first displacement device is commercially available, and in order to improve the flexibility of adjustment, a three-dimensional displacement device on the market is used as the first displacement device, so that the position of the laser 7 can be adjusted in three directions of XYZ.
The thermal infrared imager device is used for acquiring temperature information of the surface of a material to be measured and comprises a thermal infrared imager host 12 arranged outside the fixed frame 9 and a thermal infrared imager probe 3 electrically connected with the thermal infrared imager host 12, wherein the thermal infrared imager probe 3 is movably arranged on the fixed frame 9. The thermal infrared imager probe 3 is fixed on the fixed frame 9 through the second shifter 4 with the same structure and precision as the first shifter 8, and in order to facilitate the thermal infrared imager probe 3 to acquire the temperature of the material to be detected, the thermal infrared imager probe 3 is arranged on a second side wall, perpendicular to the first inner side wall, of the fixed frame 9. The second shifter 4 can also be a three-dimensional shifter on the market, so that the position of the infrared thermal imager probe 3 can be adjusted in the three directions of XYZ, and the distance between the infrared imager probe 3 and the laser 7 can be adjusted through the second shifter 4. During measurement, the second shifter 4 is adjusted to enable the included angle between the light path of the thermal infrared imager probe 3 and the laser light path to be not larger than 30 degrees, the included angle is guaranteed to be as small as possible, in addition, the position of the thermal infrared imager probe 3 is adjusted, the material 6 to be measured is enabled to be located on the focal length of the thermal infrared imager probe 3, and therefore the thermal infrared imager host 12 can obtain a clear infrared image.
The convex lens 5 is provided on a third inner side wall opposite to the second inner side wall on the fixed frame 9 by a uniaxial displacement device. Unipolar displacement device includes servo motor and mechanical slip table 11, and mechanical slip table 11 is in including fixing the second base on fixed frame 9, fixing the second guide rail on the second base, rotationally set up the second lead screw between the second guide rail and pass through threaded connection and sliding connection with the second lead screw second slider on the second guide rail, the second lead screw still with servo motor's drive shaft connection, convex lens 5 are fixed on the second slider, and wherein, the second guide rail sets up in a parallel with laser light path direction. In order to facilitate the control servo motor, still set up the single-axis controller 10 with servo motor electrical connection again on the third inside wall, servo motor's behavior can be controlled to this single-axis controller 10, work as single-axis controller 10 control servo motor, servo motor work drives the second lead screw and rotates and then promote convex lens 5 on second slider and the second slider and move on the second guide rail, thereby realize that convex lens 5 moves along laser light path direction, and then adjust convex lens 5's position and make laser focus on the material that awaits measuring best position, produce the laser spot of suitable size on the material that awaits measuring.
The temperature measuring device is used to measure the temperature of the material to be measured, which in this embodiment is a thermocouple thermometer 13. The data receiving and processing device is used for receiving and processing corresponding signals and is electrically connected with the thermal infrared imager main unit 12 and the thermocouple thermometer 13. In this embodiment, the data receiving and processing device is a data processing computer, the data processing computer 2 can control the sampling frequency and the sampling position of the thermal infrared imager host 12, and the surface emissivity of the measured material at different temperatures can be obtained by collecting, storing and processing the measured data of the thermocouple thermometer and the measured data of the thermal infrared imager. Meanwhile, the data processing computer 2 controls the thermal infrared imager host 12 to correct emissivity parameters of the surface of the material to be measured at different temperatures according to the measured surface emissivity, so that the temperature data are accurate and reasonable. During measurement, the data collecting computer 2 sets the frequency of data collected by the thermal infrared imager host, obtains the temperature information of the sample at each moment, and records the transient temperature response and the steady-state temperature response. At the same time, data collectionThe computer 2 processes and stores the data to obtain a real-time temperature distribution map of the material 6 to be measured, and performs linear and nonlinear fitting on the measured data to obtain the heat conductivity coefficient k, the thermal diffusion coefficient alpha and the heat capacity C of the material 6 to be measuredpAnd the like thermophysical parameters. In actual measurement, the temperature of the material to be measured 6 can be changed to study the change of the thermophysical property parameter of the measured material at different temperatures.
As shown in fig. 2, the present invention further provides a measuring method of the measuring apparatus for the multiple thermophysical parameters of the material, including the following steps:
step 1: thereby adjust and position first shifter 8, unipolar displacement device 11 and make laser instrument 7, convex lens 5 and the material 6 that awaits measuring on same light path to adjust first shifter 8 and unipolar displacement device 11, control the distance between laser instrument 7, convex lens 5 and the material 6 three that awaits measuring, make laser focus on the material 6 surface that awaits measuring and form a point heat source, guarantee laser perpendicular and the material surface that awaits measuring simultaneously. And adjusting the second shifter 4 to ensure that the included angle between the incident light path of the thermal infrared imager probe 3 and the laser light path is not more than 30 degrees. In addition, the position of the thermal infrared imager probe 3 is adjusted to enable the material 6 to be measured to be at the focal distance of the thermal infrared imager probe 3, so that the thermal infrared imager host 12 can obtain a clear infrared image;
step 2: heating the sample by using a laser 7, and under the heating of different powers, acquiring temperature information of one point on the surface of the material to be detected 6 when the temperature information is stable by using a thermal infrared imager host 12 as T1And simultaneously measuring the temperature at the point as T by using a thermocouple thermodetector 132Both transmit the temperature to the data collection computer 2 and give the ambient temperature T at the time of measurement by the data collection computer 23By the following formula:
ε＝[T1 4-T3 4]/[T2 4-T3 4]
calculating to obtain the surface emissivity epsilon of the material 6 to be measured at different temperatures;
and step 3: the infrared thermal imager host 12 is used for obtaining the initial temperature picture of the material 6 to be measured, the initial temperature picture is processed by the data collecting computer 2,obtaining the initial temperature T of the material 6 to be measured0；
And 4, step 4: controlling the laser controller 1 to make the laser 7 output a constant laser signal and recording the laser power value q applied at the time0The size of the spot diameter a on the material 6 to be measured on which the laser is focused;
and 5: while the laser heating is carried out, the data collecting computer 2 controls the thermal infrared imager main machine 12 to obtain and record the instantaneous temperature signal T of the laser spot center, namely the temperature peakt；
Step 6: when the temperature distribution of the material 6 to be measured reaches the steady state, the temperature acquisition is finished to obtain a steady state temperature signal T∞And drawing a temperature-time curve;
referring to fig. 3, the heat transfer model of the measuring device can be simplified as follows: a physical model of applying constant heat flux density on the surface of a semi-infinite object in a region with a diameter a is shown in fig. 3, so that a transient temperature expression (1) and a steady-state temperature expression (2) of the highest point of the central temperature of the light spot can be obtained:
wherein, TtThe central temperature of the laser spot on the material 6 to be measured at the moment T, T0Is the spot center temperature at time 0, i.e. the initial temperature, T∞The central temperature of the laser spot after the steady state is the steady state temperature, a is the diameter of the laser spot, q0Is the laser power;
and 7: calculating the heat conductivity coefficient k, the thermal diffusion coefficient alpha and the heat capacity C of the molten salt of the material 6 to be measured at different temperatures through the expressionpThe thermal conductivity k is obtained by the formula (2):
then, the thermal conductivity k is treated in the formula (1), and the thermal diffusion coefficient alpha is obtained through nonlinear curve fitting, so that the heat capacity is obtained:
in conclusion, the surface emissivity epsilon, the heat conductivity coefficient k, the heat diffusion coefficient alpha and the heat capacity C of the sample to be measured at different temperatures can be measured by the measuring device and the measuring methodpAnd the like. From the above, it is understood that the measuring apparatus and the measuring method can rapidly and nondestructively measure the thermophysical properties of the molten salt at different temperatures.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (10)
1. A measuring device for multi-thermophysical parameters of a material is characterized by comprising a fixed frame, a laser generating device, an infrared thermal imaging device, a convex lens, a temperature measuring device and a data receiving and processing device; wherein the content of the first and second substances,
the fixed frame is used for supporting the laser generating device and the infrared thermal imaging device;
the laser generating device is used for generating laser for heating the material to be detected, and comprises a laser controller and a laser electrically connected with the laser controller, and the laser is movably arranged on the fixed frame;
the thermal infrared imager device is used for acquiring temperature information of the surface of a material to be measured, and comprises a thermal infrared imager host and a thermal infrared imager probe electrically connected with the thermal infrared imager host, wherein the thermal infrared imager probe is movably arranged on the fixed frame;
the convex lens is used for generating a laser spot with a proper size, the convex lens is movably arranged on the fixed frame, and the laser, the convex lens and the material to be measured are on the same light path during measurement;
the temperature measuring device is used for measuring the temperature of the material to be measured and is electrically connected with the material to be measured;
and the data receiving and processing device is used for receiving and processing corresponding information and is electrically connected with the thermal infrared imager host and the temperature measuring device.
2. The device for measuring the multi-thermophysical parameter of the material as claimed in claim 1, wherein the laser and the thermal infrared imager probe are respectively arranged on the fixed frame through a shifter.
3. The apparatus for measuring multiple thermal parameters of a material according to claim 2, wherein the adjustment accuracy of the displacer is 10 microns.
4. The device for measuring the multiple thermophysical parameters of the material as claimed in claim 2, wherein the displacer includes a first base fixed on the fixed frame, a first guide rail fixed on the first base, a first lead screw rotatably disposed between the first guide rails, and a first slider connected with the first lead screw by a thread and slidably connected to the first guide rail, and the laser and the thermal infrared imager are respectively disposed on the sliders of the corresponding displacer.
5. The apparatus for measuring multiple thermophysical parameters of a material according to claim 1, wherein the convex lens is disposed on the fixed frame by a uniaxial displacement device, and the uniaxial displacement device controls the convex lens to move on a laser light path.
6. The device for measuring the multiple thermophysical parameters of the material as claimed in claim 5, wherein the single-axis displacement device comprises a motor and a mechanical sliding table, the mechanical sliding table comprises a second base fixed on the fixed frame, a second guide rail fixed on the second base, a second screw rod rotatably arranged between the second guide rails, and a second slider connected with the second screw rod through a thread and connected with the second guide rail in a sliding manner, the second screw rod is further connected with a driving shaft of the motor, and the convex lens is fixed on the second slider.
7. The device for measuring the polythermoplastic parameter of a material as claimed in claim 1, wherein the temperature measuring device is a thermocouple thermometer.
8. A method for measuring the multiple thermophysical parameters of the material according to any one of claims 1 to 7, characterized by comprising the following steps:
s1: adjusting the positions of the laser and the convex lens on the fixed frame to enable the laser, the convex lens and the material to be detected to be on the same light path, adjusting the distance between the laser and the convex lens to enable the laser to be focused on the surface of the material to be detected to form a point heat source, and then adjusting the position of the thermal infrared imager probe to enable the material to be detected to be located at the focal length of the thermal infrared imager probe so that the thermal infrared imager host can obtain a clear infrared image;
s2: heating the material to be measured by using a laser, and under the heating of different powers, acquiring the temperature information of a certain point on the surface of the material to be measured as T by the thermal infrared imager host through the thermal infrared imager probe1While measuring the temperature at this point as T by means of a temperature measuring device2The thermal infrared imager and the temperature measuring device transmit the temperature information to the data receiving and processing device and give the real-time environmental temperature T of the data receiving and processing device3And calculating the surface emissivity epsilon of the sample at different temperatures according to the following formula:
ε＝[T1 4-T3 4]/[T2 4-T3 4]；
s3: data receiving and processing deviceThe method comprises the steps of correcting a thermal infrared imager host in real time according to the obtained surface emissivity epsilon of a material to be measured at different temperatures, obtaining a sample initial temperature picture through a thermal infrared imager probe by using the corrected thermal infrared imager host, and then processing the sample initial temperature picture through a data receiving and processing device to obtain the initial temperature T of the measured material0；
S4: using the laser output to maintain a constant laser signal and recording the laser power value q applied at that time0The size of the spot diameter a on the material to be measured on which the laser is focused;
s5: while laser heating, the data receiving and processing device controls the thermal infrared imager host to acquire and record the instantaneous temperature signal T of the laser spot center, namely the highest temperature pointt；
S6: after the temperature distribution of the material to be measured reaches a stable state, finishing temperature acquisition to obtain a stable state temperature signal T∞And drawing a temperature-time curve; obtaining a transient temperature expression (1) and a steady-state temperature expression (2) of the highest point of the central temperature of the light spot according to the obtained temperature-time curve:
wherein, TtThe central temperature of the laser spot on the material to be measured at the moment T, T0Is the spot center temperature at time 0, i.e. the initial temperature, T∞The central temperature of the laser spot after the steady state is the steady state temperature, a is the diameter of the laser spot, q0Is the laser power;
s7: calculating the heat conductivity coefficient k, the thermal diffusion coefficient alpha and the heat capacity C of the molten salt of the material to be measured at different temperatures through the expressionpThe thermal conductivity k is obtained by the formula (2):
then, the thermal conductivity k is treated in the formula (1), and the thermal diffusion coefficient alpha is obtained through nonlinear curve fitting, so that the heat capacity is obtained:
9. the method for measuring the multiple thermophysical parameters of the material according to claim 8, wherein the laser emitted by the laser is perpendicular to the surface of the sample to be measured, and the included angle between the optical path of the thermal infrared imager probe and the optical path of the laser is not more than 30 degrees.
10. The method for measuring the material multiple thermophysical parameters of claim 8, wherein during measurement, the data receiving and processing device sets the frequency of data acquisition of the thermal infrared imager host, controls the thermal infrared imager host to correct the emissivity parameters of the surface of the material to be measured at different temperatures, obtains the temperature information of the sample at each moment, and records the transient temperature response and the steady temperature response.
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| CN114428102B (en) * | 2022-01-17 | 2024-02-23 | 哈尔滨工业大学 | Device and test method for measuring high-low temperature heat conduction physical property parameters of anisotropic material |
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