Device for measuring thermal conductivity of material

Abstract

The utility model provides a material thermal conductivity measuring device, the measuring device comprises: a power supply, a relay, a heating module, a thermal probe, a temperature acquisition module and a microprocessor module which are connected in sequence, and an upper computer, the relay comprises a first relay and a second relay which are respectively connected with the first heating module and the second heating module; the heat probe comprises a heat needle and a heat plane which are respectively connected with the first heating module and the second heating module; the microprocessor module is respectively connected with the first relay and the second relay; and the upper computer is connected with the microprocessor module. According to the device for measuring the thermal conductivity of the material, a hot needle method and a hot plane method are combined, the measuring range covers various materials such as powder, blocks, viscous liquid and biological tissues, measuring results can be directly verified through the two methods, the difference of different characters of the same material is researched, and the measuring efficiency is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of material thermal property testing, and specifically to a material thermal conductivity measuring device. Background Art

[0002] Thermal conductivity is one of the important parameters of the thermophysical properties of materials, representing the strength of the heat transfer performance of the material. At present, the methods for measuring the thermal conductivity of materials are mainly divided into steady-state method and transient method. The steady-state method often takes a long time to measure, has high requirements on the insulation conditions of the measurement system, and has a relatively high production cost. Commonly used transient measurement methods include the thermal needle method and the thermal plane method, which are based on the one-dimensional infinite length line thermal probe theory and the plane thermal probe theory, respectively. However, for various materials with different shapes and properties, the device made according to one measurement method has a very limited range of materials to be measured. Therefore, it is of great significance to provide a material thermal conductivity measurement device with a large measurement range, short measurement time, and low cost. Utility Model Content

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to solve one or more problems in the prior art. For example, one of the purposes of the present invention is to provide a material thermal conductivity measurement device that combines the thermal needle method and the thermal plane method, has a large material measurement range, a short measurement time, and a low cost.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a material thermal conductivity measuring device, which may include: a power supply, a relay, a heating module, a thermal probe, a temperature acquisition module and a microprocessor module connected in sequence, and a host computer, wherein the relay includes a first relay and a second relay, which are respectively connected to the first heating module and the second heating module; the thermal probe includes a thermal needle and a thermal plane, which are respectively connected to the first heating module and the second heating module; the microprocessor module is respectively connected to the first relay and the second relay; and the host computer is connected to the microprocessor module.

[0005] According to one or more exemplary embodiments of the present invention, the power source may include a heating power source capable of heating the thermal probe.

[0006] According to one or more exemplary embodiments of the present invention, the heating module is capable of providing an adjustable heating current.

[0007] According to one or more exemplary embodiments of the present invention, the heating module can provide a current less than and / or equal to 1A, and the accuracy may include 1mA.

[0008] According to one or more exemplary embodiments of the present invention, the heat needle and the heat plane may each include a heating wire, a thermocouple and a housing.

[0009] According to one or more exemplary embodiments of the present invention, the temperature acquisition module can transmit the acquired time and temperature data to the microprocessor module.

[0010] According to one or more exemplary embodiments of the present invention, the sampling frequency of the temperature acquisition module may be greater than and / or equal to 5 times / second.

[0011] According to one or more exemplary embodiments of the present invention, the microprocessor module can control the switch of the relay, send instructions to the temperature acquisition module, and transmit time and temperature data to the host computer.

[0012] According to one or more exemplary embodiments of the present invention, the host computer can send instructions to the microprocessor module, receive time and temperature data, and calculate and display thermal conductivity.

[0013] According to one or more exemplary embodiments of the present invention, the measuring device may further include an ammeter, which is connected to the power supply and the thermal probe, respectively, and can display real-time current.

[0014] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0015] (1) The material thermal conductivity measuring device provided by the utility model has a wider range of measuring materials, supports dual-channel simultaneous measurement, and has more accurate measurement results.

[0016] (2) The material thermal conductivity measuring device provided by the utility model combines the hot needle method and the hot plane method, and the measurement range covers a variety of materials such as powders, blocks, viscous liquids and biological tissues. The measurement results can be directly verified by the two methods to study the differences in different properties of the same material, thereby effectively improving the measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects and / or features of the present invention will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0018] Figure 1 A schematic structural diagram of a material thermal conductivity measuring device in an exemplary embodiment of the utility model is shown;

[0019] Figure 2A Shows Figure 1 Schematic diagram of the structure of the medium heat needle;

[0020] Figure 2B Shows Figure 1 Schematic diagram of the structure of the medium heat plane;

[0021] Figure 3AA circuit diagram of a heating module in a material thermal conductivity measuring device in an exemplary embodiment of the utility model is shown;

[0022] Figure 3B Another circuit diagram of a heating module in a material thermal conductivity measuring device in an exemplary embodiment of the utility model is shown;

[0023] Figure 4A Shows Figure 1 A circuit diagram of a microprocessor module;

[0024] Figure 4B Shows Figure 1 Another circuit diagram of a microprocessor module in;

[0025] Figure 5 A schematic diagram showing a material thermal conductivity measuring device in an exemplary embodiment of the present utility model during operation is shown.

[0026] Description of reference numerals:

[0027] 1- Heating wire, 2- Thermocouple, 3- Metal shell, 4- High thermal conductivity silicone grease, 5- Thin film shell. DETAILED DESCRIPTION

[0028] Hereinafter, the material thermal conductivity measuring device of the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0029] It should be noted that "I" and "II" are only for the convenience of distinction and description, and do not indicate or imply importance or order. Relay I may also be the first relay, relay II may also be the second relay, heating module I may also be the first heating module, and heating module II may also be the second heating module. The terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0030] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0031] Exemplary Embodiment 1

[0032] Figure 1A schematic structural diagram of a material thermal conductivity measuring device in an exemplary embodiment of the utility model is shown; Figure 2A Shows Figure 1 Schematic diagram of the structure of the medium heat needle; Figure 2B Shows Figure 1 Schematic diagram of the structure of the medium heat plane; Figure 3A A circuit diagram of a heating module in a material thermal conductivity measuring device in an exemplary embodiment of the utility model is shown; Figure 3B Another circuit diagram of a heating module in a material thermal conductivity measuring device in an exemplary embodiment of the utility model is shown; Figure 4A Shows Figure 1 A circuit diagram of a microprocessor module; Figure 4B Shows Figure 1 Another circuit diagram of a microprocessor module in; Figure 5 A schematic diagram showing a material thermal conductivity measuring device in an exemplary embodiment of the present utility model during operation is shown.

[0033] The present exemplary embodiment provides a material thermal conductivity measurement device that combines a thermal needle method and a thermal plane method.

[0034] like Figure 1 As shown in the figure, the material thermal conductivity measuring device combining the hot needle method and the hot plane method mainly includes a heating power supply, a host computer, a microprocessor module, a temperature acquisition module, a relay I, a relay II, a heating module I, a heating module II, a hot needle, a hot plane and a digital display ammeter.

[0035] In this exemplary embodiment, the heating power supply can be connected to a digital display ammeter and a relay to provide power for heating the thermal probe. The host computer can be connected to a microprocessor module to calculate and display data transmitted by the microprocessor. The microprocessor can be connected to the host computer, the temperature acquisition module, and the relay to record the measured time and temperature data and control the switch of the relay. The heating module can be connected to the heating wire in the hot needle and the hot plane to provide an adjustable heating current. The hot needle and the hot plane can both be composed of a heating wire, a thermocouple and a housing. The digital display ammeter can be used to display real-time current.

[0036] In this exemplary embodiment, Figure 2A As shown in , the hot needle may include a stainless steel metal shell, a heating wire 1, a thermocouple 2 and a high thermal conductivity silicone grease 4. The metal shell 3 may be cylindrical, with a diameter of 2 mm and a height of 15 cm, and a structure for fixing the heating wire and the thermocouple on the top. The heating wire may be a nickel-chromium alloy wire with a diameter of 0.2 mm, and the thermocouple may be a K-type thermocouple, with the node located in the middle of the metal shell. High thermal conductivity silicone grease may be filled in the metal shell. The external leads of the heating wire and the thermocouple are encapsulated in a cable. As shown in Figure 2BAs shown in , the thermal plane may include a heating wire 1, a thermocouple 2 and a film housing 5. The thermal plane may be a circular plane with a radius of 2 cm, the film housing may be resistant to high temperatures, and has a thickness of 0.1 mm, the heating wire is sealed in the plane in the form of a double helix, and a K-type thermocouple is attached to the surface of the circular plane.

[0037] In this exemplary embodiment, the core component of the temperature acquisition module can be an eight-channel thermocouple temperature measurement module, model ZAM6218A, which can perform up to eight-channel thermocouple temperature measurement, and internally adopts a 24-bit Sigma-Delta ADC for thermocouple signal sampling to achieve high resolution and high precision of temperature measurement. The module is connected to the microprocessor module through a standard IIC communication interface. The thermocouple of the hot needle is connected to channel one through a filter circuit, and the thermocouple of the hot plane is connected to channel two through a filter circuit. Eight TMP116 chips are selected as thermocouple cold end compensation, and the average value of the temperature read by the eight chips is taken as the cold end compensation value.

[0038] In this exemplary embodiment, Figure 3A and Figure 3B As shown in , the main structure of the heating module circuit can be a constant current source circuit composed of an operational amplifier U4.1 and a power transistor Q1, and CN2 is a heating wire interface. The operational amplifier uses a low-cost LM358 chip, and the power transistor uses a TIP142G chip, which is a Darlington bipolar power transistor with a maximum power of 125W, which meets the requirements. The feedback path adds a differential amplifier circuit composed of an operational amplifier U6.1 and a resistor to increase the accuracy of the output current and reduce interference. The sampling resistor R42 is a 0.5 ohm power resistor, and U5 is a precision multi-turn sliding rheostat with a resistance of 100K. The 2.5V voltage connected to its pin 1 is provided by the voltage reference chip LM385M, and the pin 2 is connected to the reverse end of U4.1 via a voltage follower formed by U4.2. Here, the structure of the heating module I can be the same as that of the heating module II.

[0039] In this exemplary embodiment, Figure 4A and Figure 4B As shown in the figure, the microprocessor module circuit can use STM32F103C8T6 as the main control chip, pins 42 and 43 are IIC function pins, connected to the temperature acquisition module to achieve data transmission and control. Pins 45 and 46 are used to control the switch of the relay, and pins 30 and 31 are serial port pins, which are connected to the host computer through a USB cable to achieve data transmission between the microprocessor module and the host computer.

[0040] In this exemplary embodiment, Figure 5 As shown in the figure, the thermal conductivity measuring device of the material using the hot needle method and the hot plane method is used to measure the powder and block of the same material, which may include:

[0041] Pour the solid powder into a cylindrical container with a diameter of 10 cm. The height of the powder should be enough to cover the heating needle. Make two cylindrical materials with the same diameter as the hot plane, and each piece is 2 cm high.

[0042] Before the measurement begins, place the hot needle and hot plane in the air, turn on the measuring device through the host computer, read the temperature at this time, record it as T0, turn on the relay, watch the digital ammeter, adjust the current to a value between 0 and 1A by rotating the sliding rheostat, which can be 0.2A, turn off the relay, and wait for the hot needle and hot plane to cool to the temperature T0 read at the beginning;

[0043] Insert the hot needle into the powdered material from the center of the circle until the powder covers the hot needle, clamp the hot plane between two pieces of material and press them tightly with a heavy object;

[0044] Start the heating and temperature measurement program on the host computer and read the time and temperature data;

[0045] The host computer fits the slope based on the heating current and the collected time-temperature data through the least squares method, thereby calculating the thermal conductivity of the material to be tested.

[0046] Here, a voltage-stabilized DC power supply of model UTP1305 can be used as a heating power supply, with a maximum output DC voltage of 33V and a maximum output current of 5A.

[0047] Exemplary Embodiment 2

[0048] The present exemplary embodiment provides a device for measuring thermal conductivity of a material.

[0049] The measuring device may include: a power supply, a relay, a heating module, a thermal probe, a temperature acquisition module and a microprocessor module, which are connected in sequence, and a host computer.

[0050] Wherein, the relay includes a first relay and a second relay, which are respectively connected to the first heating module and the second heating module, the thermal probe includes a hot needle and a hot plane, which are respectively connected to the first heating module and the second heating module, the microprocessor module is respectively connected to the first relay and the second relay, and the host computer is connected to the microprocessor module. The power supply may include a heating power supply, which can heat the thermal probe. The hot needle and the hot plane can both include a heating wire, a thermocouple and a shell. The measuring device can also include an ammeter, which is respectively connected to the power supply and the thermal probe and can display real-time current.

[0051] In this exemplary embodiment, the heating module can provide an adjustable heating current. The heating module can provide a current less than and / or equal to 1A, the accuracy can include 1mA, the output current can be adjusted by a sliding resistor, and the current value change during measurement is within 3mA.

[0052] In this exemplary embodiment, the temperature acquisition module can transmit the collected time and temperature data to the microprocessor module. The sampling frequency of the temperature acquisition module can be greater than and / or equal to 5 times / second. Here, the temperature acquisition module can collect the temperature values ​​of the thermocouple at different times.

[0053] In this exemplary embodiment, the microprocessor module can record the measured time and temperature data, control the switch of the relay, send instructions to the temperature acquisition module, and transmit the time and temperature data to the host computer. The host computer is used to calculate and display the data sent by the microprocessor module. The host computer can send instructions to the microprocessor module, receive time and temperature data, and calculate and display thermal conductivity.

[0054] In this exemplary embodiment, the use process / working principle of the material thermal conductivity measuring device may include:

[0055] Pour the material to be tested into a cylindrical container, the material height can cover the heating needle, and make two cylindrical materials with the same diameter as the heating plane. Here, the material to be tested can be one or more of powder, block, viscous liquid and biological tissue;

[0056] Before the measurement begins, place the hot needle and hot plane in the air, turn on the measuring device through the host computer, read the temperature at this time, record it as T0, turn on the relay, watch the digital ammeter, adjust the current to 0-1A by rotating the sliding rheostat, for example, 0.2A, 0.3A, 0.5A, 0.7A or 0.9A, turn off the relay, and wait for the hot needle and hot plane to cool to the temperature T0 read at the beginning;

[0057] Insert the hot needle into the material to be tested from the center of the circle, so that the material does not pass through the hot needle. Clamp the hot plane between two pieces of material and press them tightly with a heavy object.

[0058] Start the heating and temperature measurement program on the host computer and read the time and temperature data;

[0059] The host computer fits the slope based on the heating current and the collected time-temperature data through the least squares method, thereby calculating the thermal conductivity of the material to be tested.

[0060] Here, a voltage-stabilized DC power supply of model UTP1305 can be used as a heating power supply, with a maximum output DC voltage of 33V and a maximum output current of 5A.

[0061] In summary, the material thermal conductivity measuring device provided by the utility model combines the hot needle method and the thermal plane method, and the measurement range covers a variety of materials such as powders, blocks, viscous liquids and biological tissues. The measurement results can be directly verified by the hot needle method and the thermal plane method, and the differences in different properties of the same material can also be studied, effectively improving the measurement efficiency.

[0062] Although the material thermal conductivity measuring device of the present invention has been described above in conjunction with exemplary embodiments, those skilled in the art should appreciate that various modifications and changes may be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined in the claims.

Claims

1. A material thermal conductivity measuring device, characterized in that: The measuring device comprises: a power supply, a relay, a heating module, a thermal probe, a temperature acquisition module and a microprocessor module, and a host computer connected in sequence, wherein: The relay includes a first relay and a second relay, which are respectively connected to the first heating module and the second heating module; The thermal probe includes a thermal needle and a thermal plane, which are respectively connected to the first heating module and the second heating module; The microprocessor module is connected to the first relay and the second relay respectively; The host computer is connected to the microprocessor module.

2. The material thermal conductivity measuring device according to claim 1, characterized in that: The power supply includes a heating power supply, which can heat the thermal probe.

3. The material thermal conductivity measuring device according to claim 1, characterized in that: The heating module is capable of providing an adjustable heating current.

4. The material thermal conductivity measuring device according to claim 3, characterized in that: The heating module is capable of providing a current less than and / or equal to 1 A, with an accuracy of 1 mA.

5. The material thermal conductivity measuring device according to claim 1, characterized in that: The heat needle and the heat plane both include a heating wire, a thermocouple and a housing.

6. The material thermal conductivity measuring device according to claim 1, characterized in that: The temperature acquisition module transmits the acquired time and temperature data to the microprocessor module.

7. The material thermal conductivity measuring device according to claim 6, characterized in that: The temperature acquisition module performs sampling at a frequency greater than and / or equal to 5 times per second.

8. The material thermal conductivity measuring device according to claim 1, characterized in that: The microprocessor module can control the switch of the relay, send instructions to the temperature acquisition module, and transmit time and temperature data to the host computer.

9. The material thermal conductivity measuring device according to claim 1 or 8, characterized in that: The host computer can send instructions to the microprocessor module, receive time and temperature data, and calculate and display thermal conductivity.

10. The material thermal conductivity measuring device according to claim 1, characterized in that: The measuring device also includes an ammeter, which is connected to the power supply and the thermal probe respectively and can display real-time current.

Images