JP2016031330A - Thermal conductivity measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal conductivity measuring system capable of accurately measuring the thermal conductivity of a sample even if a magnetic field or an electric field is applied to the sample.SOLUTION: A thermal conductivity measuring system comprises: electric field/magnetic field application means; temperature gradient prediction means; temperature gradient adjustment means; and thermal conductivity measuring means. The electric field/magnetic field application means applies an electric field or a magnetic field to a sample. The temperature gradient prediction means predicts a temperature gradient within the sample on the basis of temperatures detected at a plurality of points in the sample. The temperature gradient adjustment means heats or cools the sample in order to eliminate the temperature gradient predicted by the temperature gradient prediction means when the electric field/magnetic field application means applies the electric field or the magnetic field to the sample. The thermal conductivity measuring means measures the thermal conductivity of the sample in a state in which the temperature gradient adjustment means heats or cools the sample.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermal conductivity measurement technique.

  Conventionally, a technique for measuring the thermal conductivity of a sample is known. For example, Patent Document 1 discloses a thermal conductivity in which a temperature difference between both surfaces of a sample whose thermal conductivity is to be measured and a heat flow rate flowing in the thickness direction of the sample are respectively measured and the thermal conductivity is obtained by a predetermined calculation formula. A technique for controlling the average temperature of a sample by disposing a pair of thermoelectric conversion devices in close contact with the sample in the measurement device is disclosed.

JP-A-63-290949

  When obtaining the thermal conductivity of a sample with different resistivity inside when applying a magnetic field or electric field, a temperature gradient occurs in the sample due to the heat generated by the sample itself due to the current generated by applying the magnetic field or electric field. . In this case, there is a problem that an accurate thermal conductivity cannot be obtained.

  The present invention has been made to solve the above-described problems, and is capable of accurately measuring the thermal conductivity of a sample even when a magnetic field or an electric field is applied to the sample. The main purpose is to provide a rate measurement system.

  In one aspect of the present invention, a thermal conductivity measurement system for measuring the thermal conductivity of a sample is based on electric field / magnetic field applying means for applying an electric field or a magnetic field to the sample, and temperatures detected at a plurality of points in the sample. A temperature gradient predicting means for predicting a temperature gradient inside the sample and a temperature gradient predicted by the temperature gradient predicting means when an electric field or a magnetic field is applied by the electric field / magnetic field applying means. Temperature gradient adjusting means for heating or cooling the sample, and thermal conductivity measuring means for measuring the thermal conductivity of the sample in a state where the sample is heated or cooled by the temperature gradient adjusting means.

  The thermal conductivity measuring system includes an electric field / magnetic field applying unit, a temperature gradient predicting unit, a temperature gradient adjusting unit, and a thermal conductivity measuring unit. The electric field / magnetic field applying means applies an electric field or a magnetic field to the sample. The temperature gradient predicting means predicts a temperature gradient inside the sample based on temperatures detected at a plurality of points in the sample. The temperature gradient adjusting means heats or cools the sample so as to eliminate the temperature gradient predicted by the temperature gradient predicting means when an electric field or magnetic field is applied by the electric field / magnetic field applying means. The thermal conductivity measuring means measures the thermal conductivity of the sample while the sample is heated or cooled by the temperature gradient adjusting means. According to this aspect, the thermal conductivity measurement system can accurately measure the thermal conductivity of a sample to which an electric field or a magnetic field is applied.

It is a block diagram which shows the structure of the thermal conductivity measuring system which concerns on embodiment. (A) is a figure which shows the outline | summary of a temperature gradient detection process. (B) shows the estimated value of the temperature in the thermal conductivity variable material based on the detected value of the radiation thermometer. (A) is a figure which shows the outline | summary of a temperature gradient adjustment process. (B) shows the relationship between the coordinates in the thermal conductivity variable material and the temperature during heating by the adjustment heating unit. It is a figure which shows the outline | summary of a thermal conductivity measurement process.

  Hereinafter, preferred embodiments of an electric vehicle according to the present invention will be described with reference to the drawings.

[Configuration of thermal conductivity measurement system]
FIG. 1 is a block diagram showing the configuration of the thermal conductivity measurement system according to this embodiment. The thermal conductivity measurement system is a system for measuring the thermal conductivity of the thermal conductivity variable material 1 as a sample, and includes a power source 2, a thermal conductivity measuring device 3, a radiation thermometer 4, and an adjustment heating unit. 5 and a heating part 6 for measurement.

  The thermal conductivity variable material 1 is a laminated body of a first material 11 and a second material 12, and the thermal conductivity changes depending on whether an electric field or a magnetic field is applied. FIG. 1 shows a state in which a predetermined voltage is applied to the heat conductivity variable material 1 by a power source 2. Further, the first material 11 has a higher resistivity than the second material 12. Therefore, the amount of heat generated by the first material 11 when a voltage is applied from the power source 2 is greater than the amount of heat generated by the second material 12.

  The radiation thermometer 4 performs radiation side temperature for the thermal conductivity variable material 1. The radiation thermometer 4 measures the temperature at the second surface 9d, which is the surface of the thermal conductivity variable material 1 on the second material 12 side, when measuring the thermal conductivity. Further, the radiation thermometer 4 detects the temperature gradient in the thermal conductivity variable material 1 before the measurement of the thermal conductivity, and the temperature of the boundary surface 9m, the thermal conductivity variable material 1 on the first material 11 side. The temperature of the first surface 9u, which is the surface, and the temperature of the second surface 9d are measured.

  The adjustment heating unit 5 is a laser for heating the heat conductivity variable material 1 from the second surface 9d. The adjustment heating unit 5 is used to cancel the temperature gradient generated in the heat conductivity variable material 1 (that is, to set the temperature gradient to 0). The measurement heating unit 6 is a laser for heating the thermal conductivity variable material 1 from the first surface 9 u for the purpose of measuring thermal conductivity. The heating unit for adjustment 5 and the heating unit for measurement 6 are switched on and off based on the control of the thermal conductivity measuring device 3.

  The thermal conductivity measuring device 3 measures the thermal conductivity of the variable thermal conductivity material 1 when a voltage is applied, based on a laser flash method. At this time, the thermal conductivity measuring device 3 has a thermal conductivity caused by a current generated by applying a voltage to the thermal conductivity variable material 1 and a difference in resistivity between the first material 11 and the second material 12. The second surface 9 d is heated by the adjustment heating unit 5 so as to eliminate the temperature gradient in the variable material 1. And the thermal conductivity measuring apparatus 3 calculates | requires the thermal conductivity of the thermal conductivity variable material 1 by heating the 1st surface 9u by the heating part 6 for a measurement, and measuring the temperature change of the 2nd surface 9d.

[Measurement method]
Next, the measurement method of the heat conductivity which the heat conductivity measuring apparatus 3 performs is demonstrated. Schematically, the thermal conductivity measurement device 3 detects a temperature gradient that occurs when a voltage is applied to the thermal conductivity variable material 1 (also referred to as “temperature gradient detection process”), and eliminates the detected temperature gradient. The process of heating the thermal conductivity variable material 1 by the adjustment heating unit 5 (also referred to as “temperature gradient adjustment process”) and the process of measuring the thermal conductivity of the thermal conductivity variable material 1 by the laser flash method (“ Also referred to as “thermal conductivity measurement process”). Thereby, the thermal conductivity measuring device 3 accurately measures the thermal conductivity of the variable thermal conductivity material 1 changed by the action of an electric field or a magnetic field.

(1) Temperature gradient detection process FIG. 2A is a diagram showing an outline of the temperature gradient detection process. As shown in FIG. 2A, the radiation thermometer 4 has a temperature “Tu” at the first surface 9u, a temperature “Tm” at the boundary surface 9m, and a temperature “Tm” at the second surface 9d, depending on the radiation side temperature. Td ”is acquired and supplied to the thermal conductivity measuring device 3.

  FIG. 2B shows an estimated value of the temperature in the thermal conductivity variable material 1 based on the detection value of the radiation thermometer 4. The vertical axis “distance” in the graph shown in FIG. 2B represents the distance from the second surface 9d to each position in the thermal conductivity variable material 1 when the vertical direction of the second surface 9d is used as a reference. Show. Moreover, the measurement point 21 shows the measurement result when the second surface 9d is radiated side temperature, the measurement point 22 shows the measurement result when the boundary surface 9m is radiated side temperature, and the measurement point 23 is the first point. The measurement result when the surface 9u is subjected to radiation side temperature is shown.

  As shown in FIG. 2B, the first material 11 has a higher resistivity and a larger amount of heat generation than the second material 12, and therefore approaches the first surface 9u on the first material 11 side far from the second material 12. The measured temperature becomes higher, and the measured temperature becomes lower as it approaches the second surface 9d on the second material 12 side far from the first material 11. In this case, the thermal conductivity measuring device 3 recognizes a straight line (that is, a linear expression) indicating the relationship between the temperature and the distance L on the basis of the measurement points 21 to 23, and determines the slope “θ” of the graph of the straight line. This is recognized as a temperature gradient of the thermal conductivity variable material 1 generated when a voltage is applied.

(2) Temperature gradient adjustment process FIG. 3A is a diagram showing an outline of the temperature gradient adjustment process. As shown in FIG. 3A, in the temperature gradient adjustment process, the thermal conductivity measuring device 3 heats the thermal conductivity variable material 1 from the second surface 9d on the low temperature side by the adjustment heating unit 5. . In this case, the thermal conductivity measurement device 3 increases the output of the adjustment heating unit 5 as the inclination θ detected by the temperature gradient detection process increases. Specifically, the thermal conductivity measuring device 3 preliminarily displays a map or an expression indicating the output value of the adjustment heating unit 5 necessary for canceling the temperature gradient of the inclination θ for each assumed inclination θ. It memorize | stores in memory etc. and the output of the heating part 5 for adjustment is determined with reference to the said map.

  FIG. 3B shows the temperature in the thermal conductivity variable material 1 during heating by the adjustment heating unit 5. Here, the measurement point 21A shows the measurement result when the second surface 9d is radiated side temperature, the measurement point 22A shows the measurement result when the boundary surface 9m is radiated side temperature, and the measurement point 23A is The measurement result when one surface 9u is subjected to radiation side temperature is shown.

  As shown in FIG. 3B, in this case, as a result of the second surface 9d on the lower temperature side being heated according to the inclination θ by the adjustment heating unit 5, the measured temperature Td on the second surface 9d, The measured temperature Tm at the boundary surface 9m and the measured temperature Tu at the first surface 9u are equal to each other, and the temperature gradient in the thermal conductivity variable material 1 is eliminated.

(3) Thermal conductivity measurement process FIG. 4 is a diagram showing an outline of the thermal conductivity measurement process. As shown in FIG. 4, in the thermal conductivity measurement process, the thermal conductivity measurement device 3 is configured such that the second surface 9 d is heated by the adjustment heating unit 5 based on the gradient detection process, and the thermal conductivity variable material 1 is heated. Measure the thermal conductivity. In the example of FIG. 4, the thermal conductivity measuring device 3 calculates the thermal conductivity of the thermal conductivity variable material 1 by the laser flash method, and therefore the thermal conductivity variable material 1 from the first surface 9 u by the measurement heating unit 6. And the temperature Td of the second surface 9d is measured by the radiation thermometer 4. And the thermal conductivity measuring apparatus 3 calculates thermal conductivity based on the change of temperature Td. In this case, since the temperature gradient in the thermal conductivity variable material 1 is canceled by the heating of the adjustment heating unit 5, the thermal conductivity measuring device 3 performs the thermal conduction of the thermal conductivity variable material 1 to which a voltage is applied. The rate can be measured accurately.

[Modification]
Next, a modified example suitable for the above-described embodiment will be described.

(Modification 1)
The thermal conductivity variable material 1 is not limited to a multilayer structure as shown in FIG. 1, and may have a single layer structure in which the resistivity varies. Even in this case, the thermal conductivity measuring device 3 detects the temperature gradient in the thermal conductivity variable material 1 by measuring the temperature at a plurality of points of the thermal conductivity variable material 1. And the thermal conductivity measuring apparatus 3 performs the thermal conductivity measurement process in the state which canceled the temperature gradient by heating the thermal conductivity variable material 1 with the heating part 5 for adjustment from the surface of the low temperature side.

(Modification 2)
The thermal conductivity measuring device 3 cools the thermal conductivity variable material 1 from the first surface 9u on the higher temperature side instead of heating the thermal conductivity variable material 1 from the second surface 9d on the lower temperature side. May be. In this case, the thermal conductivity measurement system has a cooling unit for cooling the thermal conductivity variable material 1 instead of the adjustment heating unit 5, and the thermal conductivity measurement device 3 is used in the temperature gradient adjustment process. The temperature gradient in the heat conductivity variable material 1 is eliminated by cooling the heat conductivity variable material 1 from the first surface 9u on the low temperature side by the cooling unit.

(Modification 3)
The thermal conductivity measuring device 3 calculates the thermal conductivity based on the laser flash method in the thermal conductivity measurement process, but is not limited to this, and various methods such as a pulse heating method, a periodic heating method, a step heating method, and a steady method are used. The thermal conductivity may be calculated by this method.

DESCRIPTION OF SYMBOLS 1 ... Thermal conductivity variable material 2 ... Power supply 3 ... Thermal conductivity measuring device 4 ... Radiation thermometer 5 ... Heating part for adjustment 6 ... Heating part for measurement 11 ... 1st material 12 ... 2nd material

Claims (1)

A thermal conductivity measurement system for measuring the thermal conductivity of a sample,
An electric field / magnetic field applying means for applying an electric field or a magnetic field to the sample;
A temperature gradient predicting means for predicting a temperature gradient inside the sample based on temperatures detected at a plurality of points in the sample;
A temperature gradient adjusting means for heating or cooling the sample so as to eliminate a temperature gradient predicted by the temperature gradient predicting means when an electric field or a magnetic field is applied by the electric field / magnetic field applying means;
Thermal conductivity measuring means for measuring the thermal conductivity of the sample in a state where the sample is heated or cooled by the temperature gradient adjusting means;
A thermal conductivity measurement system comprising:

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