Device and method for measuring thermal conductivity of material

Abstract

The invention provides a device for measuring the thermal conductivity of a material, and the device comprises a high-temperature experiment box which is used for accommodating a to-be-measured material; the heating structure is located in the high-temperature experiment box, and the output end of the heating structure is used for being in contact with the to-be-tested material; the thermal infrared imager is located in the high-temperature experiment box, and the shooting end of the thermal infrared imager is used for facing the to-be-tested material so as to obtain the temperature distribution condition of the to-be-tested material. The high-temperature experiment box is arranged to provide a constant-temperature environment for the to-be-measured material, so that the influence on the measurement precision of the thermal conductivity of the to-be-measured material due to the change of the external environment temperature is avoided, the measurement precision of the measurement device is improved, and the temperature distribution condition of the to-be-measured material can be directly obtained by arranging the thermal infrared imager; therefore, the thermal conductivity measuring time is shortened, the thermal conductivity measuring efficiency of the measuring device is improved, and the practicability and engineering applicability of the measuring device are improved.

Description

Technical Field

[0001] The present application relates to the field of measurement technology, and in particular to a device and method for measuring thermal conductivity of a material. Background Art

[0002] Due to the diversity of coating materials, there is no method suitable for measuring the thermal conductivity of various coating materials in the prior art. When applied in engineering sites, the measurement accuracy and efficiency are limited. Therefore, there is an urgent need for a material thermal conductivity measurement device to meet the requirements of measurement accuracy and efficiency in engineering applications. Summary of the invention

[0003] In view of this, the purpose of the present application is to provide a device and method for measuring the thermal conductivity of a material.

[0004] Based on the above purpose, the present application provides a device for measuring thermal conductivity of a material, comprising:

[0005] A high temperature test chamber to contain the materials to be tested;

[0006] A heating structure, located in the high temperature test box, with an output end thereof being in contact with the material to be tested;

[0007] The infrared thermal imager is located in the high temperature test box, and its shooting end is arranged toward the material to be tested to obtain the temperature distribution on the material to be tested.

[0008] Furthermore, the measuring device also includes a control system, and the control system is electrically connected to the high-temperature test box, the infrared thermal imager and the heating structure.

[0009] Furthermore, the measuring device also includes a measuring platform, which is located in the high-temperature test box and is used to carry the material to be tested.

[0010] Furthermore, the output end of the heating structure is a heating needle, and the heating needle is used to contact the center point of the material to be tested, and the infrared thermal imager is located directly above the material to be tested.

[0011] Furthermore, the heating needle is arranged in parallel with the optical path of the infrared thermal imager.

[0012] Based on the same inventive concept, the present application also provides a measurement method, which is applied to the device for measuring the thermal conductivity of the material as described above, comprising:

[0013] Place the material to be tested in a high temperature test chamber;

[0014] Starting the heating structure and increasing the output power of the heating structure until the color around the contact point between the material to be tested and the output end of the heating structure changes significantly in the image captured by the infrared thermal imager;

[0015] Acquiring an image captured by the infrared thermal imager and an output power of the heating structure;

[0016] The image captured by the infrared thermal imager and the output power of the heating structure are analyzed to obtain the thermal conductivity of the material to be tested.

[0017] Furthermore, after placing the material to be tested in the high temperature test box, the method further includes:

[0018] Adjusting the position of the infrared thermal imager so that the photographing end of the infrared thermal imager is disposed toward the material to be tested;

[0019] The position of the output end of the heating structure is adjusted so that the output end contacts the material to be tested and is arranged parallel to the optical path of the infrared thermal imager.

[0020] Furthermore, the temperature of the output end of the heating structure is 0.01-10° C. higher than the temperature of the high temperature test box.

[0021] From the above, it can be seen that the material thermal conductivity measuring device provided by the present application provides a high-temperature test box for accommodating the material to be tested, a heating structure for contacting the material to be tested, so as to provide thermal conductivity conditions for the material to be tested, and an infrared thermal imager for capturing an infrared image of the material to be tested, thereby analyzing the temperature of each position of the material to be tested under the thermal conductivity conditions provided by the heating structure, and providing a basis for the subsequent determination of the thermal conductivity of the material to be tested; the present application sets up a high-temperature test box to provide a constant temperature environment for the material to be tested, thereby avoiding the influence of the temperature change of the external environment on the accuracy of measuring the thermal conductivity of the material to be tested, which is beneficial to improving the measurement accuracy of the measuring device; the infrared thermal imager can directly obtain the temperature distribution of the material to be tested, thereby shortening the measurement time of the thermal conductivity, improving the efficiency of the measuring device in measuring the thermal conductivity, and being beneficial to improving the practicality and engineering applicability of the measuring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a schematic diagram of the structure of a device for measuring thermal conductivity of materials in an embodiment of the present application;

[0024] Figure 2 This is a schematic diagram of the process structure of the measurement method of the embodiment of the present application.

[0025] In the figure: 10, high temperature test box; 20, heating structure; 21, heating needle; 30, infrared thermal imager; 40, measuring platform; 50, PC. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0027] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0028] In terms of measuring the thermal conductivity of coating materials, due to the diverse structures of coating materials, there is currently no commercial instrument that can replace the laboratory measurement of the thermal conductivity of coating materials, nor is there a laboratory measurement method suitable for measuring the thermal conductivity of all coating materials. Therefore, a variety of experimental measurement methods are constantly being developed and improved.

[0029] Among them, the thermal conductivity measurement methods of coating materials mainly include steady-state measurement method and non-steady-state measurement method. 1. In the steady-state measurement method, the outside world applies a certain heat flow to the measurement sample until the temperature distribution in the measurement sample is a steady-state temperature field that does not change with time. When the measurement sample reaches thermal equilibrium, the Fourier equation can be used to directly determine the thermal conductivity of the measurement sample with the help of the heat flow rate and temperature gradient per unit area of ​​the measurement sample; 2. In the non-steady-state measurement method, the rate of change of the temperature distribution in the sample is measured, and the thermal diffusion coefficient of the measurement sample can generally be directly determined. Then, the thermal conductivity can be calculated from the thermal diffusion coefficient, specific heat and density.

[0030] In summary, the principle of the steady-state measurement method is simple, and it can directly measure thermal conductivity. The accuracy and precision of the measurement results are good, but the heat flow needs to be precisely controlled during the measurement process, and the measurement time is long. The measurement process needs to be carried out under good thermal protection measures; the non-steady-state method shortens the measurement time and reduces the requirements for measurement sample preparation, but there are also problems such as the precision and complexity of the measuring instrument components and the susceptibility of the temperature sensing process to environmental influences, which limits its application in engineering sites.

[0031] In engineering applications, the thermal conductivity measurement method of coating materials should not only meet the accuracy and precision requirements of thermal conductivity measurement, but also have the characteristics of single-sided non-contact non-destructive measurement, short measurement time, stable, reliable and lightweight test instruments, etc. Therefore, a material thermal conductivity measurement device is urgently needed to meet the application of engineering sites.

[0032] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0033] In some embodiments, Figure 1 As shown, a device for measuring thermal conductivity of a material comprises:

[0034] A high temperature test box 10, used to contain the material to be tested;

[0035] A heating structure 20 is located in the high temperature test box 10, and its output end is used to contact the material to be tested;

[0036] The infrared thermal imager 30 is located in the high temperature test box 10, and its shooting end is arranged toward the material to be tested to obtain the temperature distribution on the material to be tested.

[0037] Specifically, the high temperature test box 10 is provided with an infrared thermal imager 30 and a heating structure 20. The material to be tested is located in the high temperature test box 10 and is arranged opposite to the shooting end of the infrared thermal imager 30 so that the infrared thermal imager 30 can shoot the material to be tested. The output end of the heating structure 20 has a temperature, and the output end is in contact with the material to be tested to transfer the temperature to the material to be tested. The contact point between the material to be tested and the output end receives the temperature of the output end and then conducts it to its surroundings, so that heat conduction occurs at the periphery of the contact point of the material to be tested, which is conducive to the infrared thermal imager 30 shooting the infrared image of the material to be tested. On this basis, the infrared thermal imager 30 analyzes the obtained infrared image to obtain the temperature distribution on the material to be tested at different times, and based on this, the thermal conductivity of the material to be tested can be analyzed based on the non-steady-state measurement method.

[0038] The high temperature test box 10 is used to provide a constant temperature measurement environment for the material to be tested, thereby stabilizing the measurement environment of the measuring device and avoiding environmental influences, thereby improving the measurement accuracy of the measuring device. The temperature of the high temperature test box 10 is between 0 and 200°C.

[0039] The heating structure 20 includes a standard resistor, a graphite electrode, a copper electrode, a sample and an output terminal which are connected in sequence.

[0040] The infrared thermal imager 30 includes an infrared detector and an optical imaging objective lens. The infrared detector and the optical imaging objective lens receive the infrared radiation energy distribution pattern of the material to be tested, and reflect it on the photosensitive element of the infrared detector, thereby obtaining an infrared thermal image. Different colors on the infrared thermal image represent different temperatures. Therefore, the temperature distribution on the material to be tested can be obtained through the infrared thermal imager 30.

[0041] The infrared thermal imager 30 is a recording instrument that can record the temperature distribution of the material to be tested in real time. By analyzing the temperature changes at the same position at different times, the thermal conductivity of the material to be tested can be obtained.

[0042] It should be noted that the analysis of the temperature distribution of the material to be measured obtained by the infrared thermal imager 30 can be performed manually or by analysis software. The use of analysis software for analysis can improve the measurement efficiency of the measuring device. Therefore, a PC 50 installed with analysis software is connected to the infrared thermal imager 30 to receive the temperature distribution obtained by the infrared thermal imager 30 and perform analysis. Correspondingly, the heating structure 20 and the high temperature test box 10 are also connected to the PC 50 to obtain the power and temperature of the heating structure 20 and the high temperature test box 10, so that the analysis software can analyze and obtain the thermal conductivity of the material to be measured.

[0043] In this embodiment, a high-temperature test box 10 is provided to accommodate the material to be tested, a heating structure 20 is provided to contact the material to be tested, so as to provide thermal conductivity conditions for the material to be tested, and an infrared thermal imager 30 is provided to capture an infrared image of the material to be tested, and then the temperature of each position of the material to be tested under the thermal conductivity conditions provided by the heating structure 20 is analyzed, so as to provide a basis for the subsequent determination of the thermal conductivity of the material to be tested; the present application sets up a high-temperature test box 10 to provide a constant temperature environment for the material to be tested, thereby avoiding the influence of the temperature change of the external environment on the accuracy of measuring the thermal conductivity of the material to be tested, which is beneficial to improving the measurement accuracy of the measuring device; the infrared thermal imager 30 is provided to directly obtain the temperature distribution of the material to be tested, thereby shortening the measurement time of the thermal conductivity, improving the efficiency of the measuring device in measuring the thermal conductivity, and being beneficial to improving the practicality and engineering applicability of the measuring device.

[0044] In addition, the measuring device has a simple structure, is less affected by the environment, is relatively simple and convenient, and can meet the application requirements of engineering sites.

[0045] In some embodiments, the measuring device further includes a control system, and the control system is electrically connected to the high temperature test box 10 , the infrared thermal imager 30 , and the heating structure 20 .

[0046] Specifically, the control system is used to control the opening and closing and temperature of the high temperature test box 10, the opening and closing and output power of the heating structure 20, and the opening and closing of the infrared thermal imager 30. The control system adjusts the temperature of the output end of the heating structure 20 by adjusting the output power of the heating structure 20.

[0047] It should be noted that the control system can also be connected to a PC 50 installed with analysis software, so that the analysis software can obtain data from the high temperature test box 10, the heating structure 20 and the infrared thermal imager 30, and it is also convenient for the user to operate the control device, that is, only the PC 50 needs to be operated to control the operation and analysis of the measuring device.

[0048] In this embodiment, the control system controls the high temperature test box 10, the infrared thermal imager 30 and the heating structure 20, and can realize remote control of the measurement environment of the measuring device, avoiding affecting the measurement environment during the measurement process, which is beneficial to improving the measurement accuracy of the measuring device.

[0049] In some embodiments, the measuring device further includes a measuring platform 40 , and the measuring platform 40 is located in the high temperature test box 10 and is used to carry the material to be measured.

[0050] Specifically, the measuring platform 40 is located at the inner bottom of the high temperature test box 10 , and the material to be tested is located on the measuring platform 40 . Accordingly, the infrared thermal imager 30 is located at the inner top of the high temperature test box 10 , with its shooting end facing downward.

[0051] In this embodiment, the measuring platform 40 can provide stable support for the material to be measured and can shorten the distance between the infrared thermal imager 30 and the material to be measured, thereby facilitating improving the accuracy of the infrared thermal imager 30 in photographing the material to be measured and improving the measurement accuracy of the measuring device.

[0052] In some embodiments, the output end of the heating structure 20 is a heating needle 21, and the heating needle 21 is used to contact the center point of the material to be tested. The infrared thermal imager 30 is located directly above the material to be tested.

[0053] Specifically, the output end of the heating structure 20 is set as a heating needle 21, which can reduce the contact area between the output end and the material to be measured, and avoid the infrared thermal imager 30 delaying the capture of the temperature change of the material to be measured due to the large shielding area of ​​the output end. The setting of the heating needle 21 enables the infrared thermal imager 30 to capture the temperature change of the material to be measured in time, which is beneficial to improve the measurement accuracy of the measuring device.

[0054] The heating needle 21 is brought into contact with the center point of the material to be measured, and the infrared thermal imager 30 is arranged to be located directly above the material to be measured, so that the infrared thermal imager 30 can capture the complete temperature diffusion of the material to be measured, which is convenient for analyzing the thermal conductivity of the material to be measured and is beneficial to improving the measurement efficiency and accuracy of the measuring device.

[0055] In some embodiments, the heating needle 21 is arranged parallel to the optical path of the infrared thermal imager 30 .

[0056] Specifically, the parallel arrangement of the heating needle 21 and the optical path of the infrared thermal imager 30 can minimize the obstruction of the optical path of the infrared thermal imager 30 by the heating needle 21, thereby increasing the shooting area of ​​the infrared thermal imager 30 for the material to be measured, which is beneficial to improving the measurement accuracy of the measuring device.

[0057] In some embodiments, a measurement method is applied to the thermal conductivity measurement device of the material as described above, such as Figure 2 As shown, including:

[0058] Step S100, placing the material to be tested in a high temperature test box 10;

[0059] Specifically, the material to be tested is placed in the high temperature test box 10 and arranged opposite to the shooting end of the infrared thermal imager 30. When a measuring platform 40 is provided in the high temperature test box 10, the material to be tested is placed on the measuring platform 40.

[0060] It should be noted that after this step, the high temperature test box 10 and the infrared thermal imager 30 are started, and the temperature of the high temperature test box 10 is adjusted to a preset value for preheating.

[0061] Step S200, starting the heating structure 20 and increasing the output power of the heating structure 20 until the color around the contact point between the material to be tested and the output end of the heating structure 20 in the image captured by the infrared thermal imager 30 changes significantly;

[0062] Specifically, the output power of the heating structure 20 is increased to increase the temperature of the output end of the heating structure 20. While there is a temperature difference with the ambient temperature of the material to be tested, an obvious temperature difference can also appear on the material to be tested, so that the infrared thermal imager 30 can obtain infrared images of the material to be tested with different temperatures.

[0063] It should be noted that the output power of the heating structure 20 is not constant. When the temperature of the high-temperature test box 10 and any of the materials to be tested change, the output power of the heating structure 20 needs to be adjusted. The specific adjustment is based on the obvious color changes that can be observed in the infrared image taken by the infrared thermal imager 30.

[0064] Step S300, acquiring the image captured by the infrared thermal imager 30 and the output power of the heating structure 20;

[0065] Specifically, after determining the output power of the heating structure 20, the temperature of the material to be tested is observed through the infrared thermal imager 30 until the temperature of the material to be tested is constant, then the infrared thermal imager 30 is controlled to be turned off, the image taken by the infrared thermal imager 30 (i.e., the recorded image) is obtained, and the output power of the heating structure 20 is obtained, so as to obtain the thermal conductivity of the material to be tested through subsequent analysis.

[0066] Step S400: analyzing the image captured by the infrared thermal imager 30 and the output power of the heating structure 20 to obtain the thermal conductivity of the material to be tested.

[0067] Specifically, the thermal conductivity analysis software analyzes the image captured by the infrared thermal imager 30 in combination with the output power of the heating structure 20 to obtain the thermal conductivity of the material to be tested.

[0068] The thermal diffusion coefficient of the material to be tested can be obtained by analyzing the image taken by the infrared thermal imager 30, and the specific heat can be determined based on the output power of the heating structure 20. The density of the material to be tested is a constant, and the thermal conductivity can be calculated based on the thermal diffusion coefficient, specific heat and density.

[0069] In this embodiment, the process of measuring the thermal conductivity of the material to be measured by the measuring device is described in detail to clarify the method of using the measuring device. Starting the high-temperature insulation box before measurement can provide a constant temperature environment, which is beneficial to improving the stability of the measurement environment. After placing the material to be measured, the output power of the heating structure 20 is adjusted to determine the output power value of the heating structure 20, so that the output end of the heating structure 20 can transfer heat to the material to be measured and it can be clearly reflected on the infrared thermal imager 30, which is convenient for subsequent analysis of the image obtained by the infrared thermal imager 30, and thus is beneficial to improving the accuracy of the measurement method.

[0070] In some embodiments, after step S100: placing the material to be tested in the high temperature test box 10, the following steps are further included:

[0071] Step S500, adjusting the position of the infrared thermal imager 30 so that the shooting end of the infrared thermal imager 30 is disposed toward the material to be tested;

[0072] Specifically, according to the placement position of the material to be tested in the high temperature test box 10 (or on the measuring platform 40), the position of the infrared thermal imager 30 is adjusted so that the shooting end of the infrared thermal imager 30 is set toward the material to be tested and is directly opposite to the material to be tested. This can ensure that the material to be tested is symmetrically distributed in the infrared image taken by the infrared thermal imager 30, which is conducive to the subsequent analysis of the image taken by the infrared thermal imager 30.

[0073] Step S600 , adjusting the position of the output end of the heating structure 20 so that the output end contacts the material to be tested and is arranged parallel to the optical path of the infrared thermal imager 30 .

[0074] Specifically, after the position of the material to be measured is constant, the position of the output end of the heating structure 20 is adjusted so that the output end is in contact with the material to be measured and is parallel to the optical path of the infrared thermal imager 30, thereby minimizing the obstruction of the optical path of the infrared thermal imager 30 by the output end, which is beneficial to improving the measurement accuracy of the measuring device.

[0075] In this embodiment, the positions of the heating structure 20 and the infrared thermal imager 30 are adjusted according to the placement position of the material to be tested, which is beneficial to improving the accuracy of the measuring device in measuring the thermal conductivity of the material to be tested, thereby facilitating the practicability of the method.

[0076] In some embodiments, the temperature of the output end of the heating structure 20 is 0.01-10° C. higher than the temperature of the high temperature test chamber 10 .

[0077] Specifically, the temperature difference between the output end of the heating structure 20 and the temperature of the high temperature test box 10 is not a constant. According to existing experiments, when measuring the thermal conductivity of the coating material, the temperature of the output end of the heating structure 20 is usually 0.01 to 10°C higher than the temperature of the high temperature test box 10. The specific value is based on the color difference between the material to be tested and the output end of the heating structure 20 that can be clearly observed under the infrared thermal imager 30.

[0078] It is understandable that before using the technical solutions of each embodiment of the present disclosure, the type, scope of use, usage scenarios, etc. of the personal information involved will be informed to the user in an appropriate manner, and the user's authorization will be obtained.

[0079] For example, in response to receiving an active request from a user, a prompt message is sent to the user to clearly remind the user that the operation requested to be performed will require obtaining and using the user's personal information. Thus, the user can independently choose whether to provide personal information to software or hardware such as an electronic device, application, server, or storage medium that performs the operation of the technical solution of the present disclosure according to the prompt message.

[0080] As an optional but non-limiting implementation, in response to receiving the user's active request, the prompt information may be sent to the user in the form of a pop-up window, in which the prompt information may be presented in text form. In addition, the pop-up window may also carry a selection control for the user to choose "agree" or "disagree" to provide personal information to the electronic device.

[0081] It is understandable that the above notification and the process of obtaining user authorization are merely illustrative and do not constitute a limitation on the implementation of the present disclosure. Other methods that meet relevant laws and regulations may also be applied to the implementation of the present disclosure.

[0082] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0083] While specific details are set forth to describe exemplary embodiments of the present application, it is apparent to those skilled in the art that the present application embodiments can be implemented without these specific details or with variations in these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0084] Although the present application has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art in light of the foregoing description.

[0085] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A device for measuring thermal conductivity of a material, characterized in that: include: A high temperature test chamber to contain the materials to be tested; A heating structure, located in the high temperature test box, with an output end thereof being in contact with the material to be tested; The infrared thermal imager is located in the high temperature test box, and its shooting end is arranged toward the material to be tested to obtain the temperature distribution on the material to be tested.

2. The device for measuring thermal conductivity of a material according to claim 1, characterized in that: It also includes a control system, which is electrically connected to the high-temperature test box, the infrared thermal imager and the heating structure.

3. The device for measuring thermal conductivity of a material according to claim 1, characterized in that: It also includes a measuring platform, which is located in the high-temperature test box and is used to carry the material to be tested.

4. The device for measuring thermal conductivity of a material according to claim 1, characterized in that: The output end of the heating structure is a heating needle, and the heating needle is used to contact the center point of the material to be tested. The infrared thermal imager is located directly above the material to be tested.

5. The device for measuring thermal conductivity of a material according to claim 4, characterized in that: The heating needle is arranged parallel to the optical path of the infrared thermal imager.

6. A measurement method, applied to the material thermal conductivity measurement device as claimed in any one of claims 1 to 5, characterized in that: include: Place the material to be tested in a high temperature test chamber; Starting the heating structure and increasing the output power of the heating structure until the color around the contact point between the material to be tested and the output end of the heating structure changes significantly in the image captured by the infrared thermal imager; Acquiring an image captured by the infrared thermal imager and an output power of the heating structure; The image captured by the infrared thermal imager and the output power of the heating structure are analyzed to obtain the thermal conductivity of the material to be tested.

7. The measuring method according to claim 6, characterized in that: After placing the material to be tested in the high temperature test box, the method further includes: Adjusting the position of the infrared thermal imager so that the photographing end of the infrared thermal imager is disposed toward the material to be tested; The position of the output end of the heating structure is adjusted so that the output end contacts the material to be tested and is arranged parallel to the optical path of the infrared thermal imager.

8. The measuring method according to claim 6, characterized in that: The temperature of the output end of the heating structure is 0.01-10° C. higher than the temperature of the high temperature test box.

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