JP2021056036A - Low temperature thermal conductivity measuring device - Google Patents

Abstract

To provide a low-temperature thermal conductivity measuring device with which it is possible to suppress the consumption of liquid nitrogen or helium and cool the cooling plate of a GHP measurement device.SOLUTION: A GHP measurement device 4 which, with a pair of plates to be measured arranged on both sides of a heating plate and a pair of cooling plates further arranged respectively on outer sides of the pair of plates to be measured, measures the temperature of surface/reverse sides of each of the pair of plates to be measured, and calculates the thermal conductivity of the plates to be measured on the basis of an applied heat quantity and a difference in measured temperatures of the surface/reverse sides, is accommodated in the inside of a heat-insulating airtight container 5, and cooling means for cooling the cooling plate to low temperatures of 0°C or below is provided inside of the heat-insulating airtight container 5. To constitute the cooling means, a refrigerator 7 is provided that cools the cooling plate of the GHP measurement device 4 by heat conduction in the inside space of the heat-insulating airtight container 5.SELECTED DRAWING: Figure 1

Description

In the present invention, a pair of plate to be measured is arranged on both sides of the heating plate, a pair of cooling plates are arranged on both outer sides of the pair of plates to be measured, and the pair of plates to be measured are respectively arranged. A GHP method measuring device that measures the temperature of both the front and back sides and calculates the thermal conductivity of the flat plate to be measured based on the amount of heat given and the measured temperature difference between the front and back sides is housed inside the heat-insulating airtight container. The present invention relates to a low-temperature thermal conductivity measuring device provided with a cooling means for cooling the cooling plate to a low temperature of 0 ° C. or lower in the heat-insulating airtight container.

The GHP method measuring device is defined by the measuring method of JIS A 1412-1. Specifically, a heating plate and a pair of cooling plates are hung and supported from above so as to be movable in the plate thickness direction on the support frame. A pressing device that sandwiches the plate to be measured between the heating plate and the cooling plate, and moves the pair of plates to be measured and the pair of cooling plates close to each other around the heating plate to bring them into contact with each other. A pair is provided on both outer sides of the direction.

Conventionally, in the low temperature thermal conductivity measuring device, for example, liquid nitrogen or liquid helium is directly used or vaporized as a cooling means for cooling the cooling plate to lower the atmospheric temperature in the heat insulating airtight container, and the atmosphere thereof. It was configured as a device for cooling the cooling plate by temperature (see, for example, Non-Patent Document 1).

Building Material Test Information 12 '89 "Measurement of Thermal Conductivity in Bass Range by GHP Method"

In the conventional low-temperature thermal conductivity measuring device described above, it is difficult to lower the ambient temperature in the heat-insulating airtight container to a temperature below the boiling point of liquid nitrogen with a low-temperature gas obtained by evaporating liquid nitrogen. It was difficult to measure the conductivity in the extremely low temperature range of 180 ° C. or lower.
Therefore, as shown in FIG. 5, a device that vaporizes liquid helium (LHe) to lower the atmospheric temperature in the heat-insulating airtight container 5 formed by the vacuum heat-insulating container to an extremely low temperature region of about -268 ° C or lower. Although it is considered, in order to lower the atmospheric temperature in the heat insulating airtight container 5 by vaporizing the liquid helium, a large amount of the liquid helium must be consumed, and the liquid helium is very easily vaporized. There was a problem that it took a lot of time and effort for replenishment and storage, and it also cost a lot of money (Note that 5 in the drawing is an heat-insulating airtight container, 31 is a liquid helium storage container, and 4 is a GHP method measurement. The measuring unit 33 for accommodating the device is an opening / closing lid portion provided with a heat insulating material for opening the upper part of the heat-insulating airtight container so that the GHP method measuring device can be taken out).

Therefore, an object of the present invention is to provide a low-temperature thermal conductivity measuring device capable of solving the above-mentioned problems, suppressing the consumption of liquid nitrogen and helium, and cooling the cooling plate of the GHP method measuring device.

The first characteristic configuration of the present invention is to arrange a pair of plate to be measured on both sides of the heating plate, and further to arrange a pair of cooling plates on both outer sides of the pair of plates to be measured, and to arrange the pair of cooling plates. A GHP method measuring device that measures the temperature of both the front and back surfaces of each flat plate to be measured and calculates the thermal conductivity of the flat plate to be measured based on the amount of heat given and the measured temperature difference between the front and back surfaces. A low-temperature thermal conductivity measuring device provided in the heat-insulating airtight container with a cooling means housed inside the airtight container and cooling the cooling plate to a low temperature of 0 ° C. or lower, for forming the cooling means. A refrigerator is provided in the inner space of the heat-insulating airtight container to cool the cooling plate of the GHP method measuring device by heat conduction.

According to the first characteristic configuration of the present invention, in order to configure the cooling means, a refrigerator for cooling the cooling plate of the GHP method measuring device by heat conduction is provided in the inner space of the heat insulating airtight container. As a result, the consumption of liquid nitrogen and helium can be suppressed, and the cooling plate of the GHP measuring device can be easily cooled.

The second characteristic configuration of the present invention is that the refrigerator is arranged below the cooling plate, and the cooling portion of the refrigerator and the cooling plate are in direct thermal contact via a first metal heat conductive member. It is in the place where it is possible to configure.

According to the second characteristic configuration of the present invention, by arranging the refrigerator below the cooling plate, it is possible to easily assemble the GHP method measuring device provided with the cooling plate into the heat insulating airtight container. Further, the cooling part of the refrigerator and the cooling plate are brought into direct thermal contact by the first metal heat conductive member, so that the cold heat from the cooling part of the refrigerator is transferred to the first metal heat conductive member. Heat is efficiently transferred to the cooling plate through the cooling plate with little heat loss.

The third characteristic configuration of the present invention is that a first metal auxiliary heat conductive member is provided which directly brings the upper portion of the cooling plate and the cooling portion into direct thermal contact.

According to the third characteristic configuration of the present invention, the cooling degree of the upper part of the cooling plate is lowered due to the delay of heat conduction from the lower part and the heat loss in the middle of heat transfer. The cold heat from the cooling plate can be directly transferred to the upper part of the cooling plate through the cooling plate, and it becomes easier to cool the cooling plate more uniformly from the top to the bottom.
Therefore, the measurement accuracy of the thermal conductivity of the flat plate to be measured can be improved.

The fourth characteristic configuration of the present invention is a second metal heat conductive member in which the refrigerator is arranged above the cooling plate and the cooling portion of the refrigerator and the upper end portion of the cooling plate are brought into thermal contact with each other. It is in the place where.

According to the fourth characteristic configuration of the present invention, the refrigerator is arranged above the cooling plate, and the cooling portion of the refrigerator and the upper end portion of the cooling plate are brought into thermal contact with each other. By providing the member, the refrigerator can directly transfer heat from the upper part of the cooling plate through the second metal heat conductive member to cool the cooling plate, and the cooling plate is cooled to a more uniform temperature from the upper part to the lower part to achieve thermal conductivity. It is possible to improve the measurement accuracy of.

The fifth characteristic configuration of the present invention is that the cooling means is provided with a metal airtight container surrounding the GHP method measuring device in the inner space of the heat insulating airtight container, and the metal airtight container is provided. A refrigerator that cools by heat conduction is provided, and a first metal heat conduction member that directly brings the metal airtight container and the cooling plate into direct thermal contact is provided.

According to the fifth characteristic configuration of the present invention, a refrigerator is provided in which a metal airtight container surrounding the GHP method measuring device is provided in the inner space of the heat insulating airtight container, and the metal airtight container is cooled by heat conduction. By providing the first metal heat conductive member that directly brings the metal airtight container and the cooling plate into direct thermal contact, the cooling plate is directly cooled by the first metal heat conductive member, and it is easy to lower the temperature to a lower temperature. it can.
In addition, the metal airtight container surrounding the GHP method measuring device, for example, evacuates the space between the heat insulating airtight container and the metal airtight container to block the intrusion of heat from the outside, while making the metal airtight. If the internal space of the container is filled with the heat exchange refrigerant gas, the cooling plate of the GHP method measuring device can be efficiently cooled through the refrigerant gas.
Furthermore, the internal space of the metal airtight container is evacuated or filled with gas (nitrogen, oxygen, helium, argon, hydrogen, etc.) at an arbitrary pressure to measure the thermal conductivity with high accuracy in various atmospheres. It can be possible.

The sixth characteristic configuration of the present invention is that the cooling part of the refrigerator is attached by being brought into contact with the lower surface of the metal airtight container, and the bottom plate of the metal airtight container and the upper part of the cooling plate are in direct thermal contact. It is in the place where the first metal auxiliary heat conduction member to be made to be provided is provided.

According to the sixth characteristic configuration of the present invention, the refrigerator directly cools the lower surface of the metal airtight container, and at the same time, the cooling plate is cooled from the lower part by the first metal heat conductive member, and the upper part of the cooling plate is It is cooled via the first metal auxiliary heat conductive member, and in the end, the cooling plate can be cooled substantially uniformly up and down.

The seventh characteristic configuration of the present invention is that the cooling part of the refrigerator is attached in contact with the ceiling plate part of the metal airtight container.

According to the seventh characteristic configuration of the present invention, the ceiling plate portion of the metal airtight container is preferentially cooled, and therefore, the internal atmosphere in the upper internal space of the metal airtight container is higher than that of the lower part. Even if gas accumulates, its internal atmosphere gas is cooled by the upper wall of the preferentially cooled metal airtight container, allowing the cooling plate to be cooled more evenly, resulting in a low temperature thermal conductivity measuring device. The measurement accuracy of is improved.

It is a vertical sectional front view of this invention. It is a front view of the main part (GHP method measuring apparatus). It is a cross-sectional plan view of this invention. (A) is a first metal heat conductive member, (b) is a first bottom plate, and (c) is a plan view in which a first metal heat conductive member is erected and attached to the first bottom plate. It is a vertical sectional front view of a conventional example. It is a vertical sectional front view of another embodiment. It is a vertical sectional front view of another embodiment. It is a vertical sectional front view of another embodiment. It is a vertical sectional front view of another embodiment. It is a vertical sectional front view of another embodiment. It is a vertical sectional front view of another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 4, a pair of plate objects to be measured 2 are arranged on both sides of the heating plate 1, and a pair of cooling plates 3 are arranged on both outer sides of the pair of plate plates 2 to be measured. A GHP method measuring device 4 that measures the temperature of both front and back surfaces of a pair of flat plates 2 to be measured and calculates the thermal conductivity of the flat plates 2 to be measured based on the measured temperature difference between the front and back surfaces. A cooling means for accommodating the inside of the airtight container 5 and cooling the cooling plate 3 to a low temperature of 0 ° C. or lower is provided in the heat insulating airtight container 5.

[First Embodiment]
To form the cooling means, a metal airtight container 6 surrounding the GHP method measuring device 4 is provided in the inner space of the heat insulating airtight container 5, and a refrigerator 7 for cooling the metal airtight container 6 by heat conduction is provided. A first metal heat conductive member 8 is provided so that the metal airtight container 6 and the cooling plate 3 are in direct thermal contact with each other.

The cooling by the refrigerator 7 is, for example, a GM refrigerator (Giford-McMahon) so that it can be cooled to a temperature called an extremely low temperature below the boiling point of liquid air, particularly to a region below liquid helium (about -268 ° C). Use a cycle-based refrigerator).

As shown in FIGS. 1 to 4, the GHP method measuring device 4 suspends and supports the heating plate 1 and the pair of cooling plates 3 from above on the support frame 15 so as to be movable in the plate thickness direction, respectively, and the heating plate 1 A pressing device that sandwiches the object to be measured plate 2 between the and the pair of cooling plates 3 and moves the pair of plates to be measured 2 and the pair of cooling plates 3 close to each other around the heating plate 1 to bring them into contact with each other. A pair of 16's are provided on both outer sides in the plate thickness direction.
The grounding portion 15A of the support frame 15 is attached to a first bottom plate 17 made of copper having a thickness of 10 mm (FIGS. 4 (b) and 2), and an anchor plate made of copper having a thickness of 3 mm with respect to the first bottom plate 17. (The first metal heat conductive member 8) is provided so as to be vertically mounted (FIG. 4 (c)), and the anchor plate is provided with a connecting portion 19 (bolt insertion hole) with the cooling plate 3 at the upper part. A long hole 20 for inserting a bolt that can be connected to the first bottom plate 17 is provided in the lower end portion 8A along the moving direction of the cooling plate 3, and the bolt insertion hole 21 corresponds to the long hole 20 in the first bottom plate. A plurality of them are provided in 17 (FIGS. 4 (a), (b), (c)).

As shown in FIG. 1, the first bottom plate 17 is fixed to the container bottom plate 24 with bolts, and the first cover portion 22 surrounding the GHP method measuring device 4 is attached to the upper surface portion of the container bottom plate 24. The container bottom plate 24 and the first cover portion 22 constitute the metal airtight container 6 capable of making the inside airtight.
A GM refrigerator is attached to the lower surface of the container bottom plate 24 in a state where the two-stage cooling unit 23A (the second cooling unit 23 is provided with a two-stage expansion chamber inside) is in contact with the GM refrigerator.
Therefore, the cold heat from the GM refrigerator is directly transferred from the cooling unit 23 of the refrigerator 7 to the cooling plate 3 via the metal airtight container 6 and the first metal heat conductive member 8.

As shown in FIG. 1, a radiation shield container 25 that further surrounds the metal airtight container 6 is provided, and the second bottom plate 26 below the radiation shield container 25 is provided with a one-stage cooling unit 23B (first) of the GM refrigerator. The cooling unit 23 is provided with a one-stage expansion chamber inside) and is connected so as to be in contact with each other.
Therefore, the radiation shield container 25 is also cooled by heat conduction from the one-stage cooling unit 23B.
The outside of the metal airtight container 6 and the radiant shield container 25 is a shield layer member 27 called super insulation in which, for example, a sheet in which aluminum is vapor-deposited on a polyimide film is laminated for radiant heat insulation, and the entire circumference thereof. Is covered.

An aluminum outer tank airtight container 28 that further surrounds the metal airtight container 6 and the radiation shield container 25 is provided.
The radiation shield container 25 and the outer tank airtight container 28 constitute a heat insulating airtight container 5 that houses the GHP method measuring device 4 inside.
The first space S1 inside the outer tank airtight container 28 and the second space S2 inside the radiation shield container 25 are depressurized by a vacuum pump to be in a vacuum heat insulating state at the time of measuring the thermal conductivity, so that the heat is insulated from the outside. The introduction of heat can be suppressed as much as possible, and the refrigerating capacity can be increased.

The metal airtight container 6 can be used as a refrigerant cooling device that evacuates the internal space thereof, or fills a specific gas to cool the cooling plate 3 through the filled gas, or conducts heat in a filled gas atmosphere. You can also measure the rate.
When the internal space of the metal airtight container 6 is filled with a specific gas having a heat exchange action, if the cold heat from the cooling unit 23 is at a temperature equal to or higher than the freezing point of the filling gas, the filling gas is filled. Acts as a heat exchange gas, and cold heat is transferred to the cooling plate 3, which has the effect of further increasing the cooling efficiency.

Further, in the above-described embodiment, the heat-insulating airtight container 5 is in a vacuum-insulated state by reducing the pressure inside the outer tank airtight container 28 and the internal space of the radiation shield container 25, but the heat generated by the GHP method measuring device is obtained. When measuring the conductivity in a low temperature region where dew condensation and freezing of the outer tank airtight container 28 are not a problem, a heat insulating container having a heat insulating material at normal pressure may be used.
However, when it is necessary to increase the cooling capacity of the cooling unit 23 of the refrigerator 7, it is necessary to increase the heat insulating capacity around the refrigerator 7 by vacuum heat insulation or the like.

[Second Embodiment]
As the cooling means, in order to cool the cooling plate 3 by the refrigerator 7, a first metal heat conductive member 8 is provided which connects the first bottom plate 17 of the metal airtight container 6 and the cooling plate 3 so as to be heat conductive. In addition, as shown in FIG. 6, it is composed of eight copper wires (for example, 20 copper wires having a diameter of 1 mm are bundled) that directly bring the first bottom plate 17 and the upper portion of the cooling plate 3 into thermal contact. A first metal auxiliary heat conductive member 29 is provided. As a result, the upper part of the cooling plate 3 is also efficiently cooled, and the thermal conductivity can be measured in the extremely low temperature region.

[Third Embodiment]
As in the first embodiment and the second embodiment, in addition to attaching the cooling part 23 of the refrigerator 7 to the lower surface of the metal airtight container 6, as shown in FIG. 7, the metal airtight container 6 may be attached so as to be in contact with the ceiling plate portion 18. The GHP method measuring device 4 is placed and fixed on the bottom plate of the metal airtight container 6.

[Fourth Embodiment]
As shown in FIG. 8, the first space S1 and the second space S2 are used as a vacuum heat insulating space, and a metal airtight container 6 surrounding the GHP method measuring device 4 is provided inside the heat insulating airtight container 5 to freeze. The refrigerator 7 is arranged above the cooling plate 3 so that the cold heat from the cooling plate 23 of the machine 7 is directly conducted to the cooling plate 3, and the cooling unit 23 of the refrigerator 7 and the upper end of the cooling plate 3 are arranged. A second metal heat conductive member 35 that is in direct thermal contact with the portion may be provided.

[Fifth Embodiment]
As shown in FIG. 9, the cold heat from the cooling unit 23 of the refrigerator 7 is directly conducted to the cooling plate 3 without providing the metal airtight container 6 as shown in FIG. 1 surrounding the GHP method measuring device 4. As described above, for example, the first bottom plate 17 (the ground contact portion 15A of the support frame 15 of the GHP method measuring device 4) in which the first metal heat conductive member 8 such as the copper anchor plate described above is connected to the cooling portion 23. (Attach) and the lower part of the cooling plate 3 may be connected.
The GHP method measuring device 4 is housed inside a heat insulating airtight container 5 provided with a vacuum layer.

Further, as in FIG. 9, in a device not provided with the metal airtight container 6, in addition to the first metal heat conductive member, a first metal auxiliary heat conductive member 29 equivalent to the copper wire is attached to the first bottom plate. It may be connected over the 17 and the upper part of the cooling plate 3.

[Other Embodiments]
Other embodiments will be described below.
In the following other embodiments, the same members as those in the above embodiments are designated by the same reference numerals.
<1> The metal airtight container 6 surrounding the GHP method measuring device 4 is configured to be directly cooled by the refrigerator 7, but the cooling plate 3 is cooled without providing the metal heat conductive member. , The metal airtight container 6 may be cooled by a gas having a heat exchange action (indirect cooling).
<2> Instead of the GM refrigerator, another mechanical refrigerator (for example, a pulse tube refrigerator or the like) can be used.
<3> The first metal heat conductive member 8 and the first metal auxiliary heat conductive member 29 may be made of other metals other than copper, for example, aluminum, as long as they have good heat conductivity. The shape may be a plate shape or a shape other than a wire.
<4> Inside the heat-insulating airtight container 5, as shown in FIG. 10, the refrigerator 7 is attached to the GHP method measuring device 4, and the second metal heat conductive member is attached from the cooling part 23 of the refrigerator 7. By conducting heat conduction directly to the cooling plate 3 via 35, a storage container 31 for vaporizing liquid nitrogen or liquid helium is provided in the internal space of the heat insulating airtight container 5 as in the conventional case to lower the atmospheric temperature. The device may be used in combination with the refrigerator 7, and in this case, it can be expected that the amount of liquid nitrogen and helium used can be reduced as compared with the conventional device, and the time that can be operated by the combined use can be expected. It can also be expected to have advantages such as extension and less time and effort for replenishing the cryogen.
<5> As shown in FIG. 11, the GHP method measuring device 4 is installed inside the heat insulating airtight container 5 formed in the vacuum heat insulating space with the first space S1 between the outer tank airtight container 28 and the metal airtight container 6. It may be provided. In this case, the refrigerator may be provided with a single-stage refrigerator. Further, a pattern in which the container 25 in FIG. 1 is not provided in the two-stage GM refrigerator may be used.

As described above, the reference numerals are given for convenience of comparison with the drawings, but the description does not limit the present invention to the configuration of the accompanying drawings. In addition, it goes without saying that it can be carried out in various modes without departing from the gist of the present invention.

1 Heating plate 2 Flat plate to be measured 3 Cooling plate 4 GHP method measuring device 5 Insulation airtight container 6 Metal airtight container 7 Refrigerator 8 1st metal heat conductive member 23 Cooling part 29 1st metal auxiliary heat conductive member 35 Second metal heat conductive member

Claims (7)

A pair of flat plates to be measured are placed on both sides of the heating plate.
A pair of cooling plates are arranged on both outer sides of the pair of flat plates to be measured.
A GHP method measuring device that measures the temperature of both front and back surfaces of each of the pair of flat plates to be measured and calculates the thermal conductivity of the flat plates to be measured based on the amount of heat given and the measured temperature difference between the front and back surfaces. A low-temperature thermal conductivity measuring device that is housed inside a heat-insulating airtight container and has a cooling means for cooling the cooling plate to a low temperature of 0 ° C. or lower in the heat-insulating airtight container.
A low-temperature thermal conductivity measuring device provided with a refrigerator for cooling the cooling plate of the GHP method measuring device by heat conduction in the inner space of the heat-insulating airtight container to constitute the cooling means. According to claim 1, the refrigerator is arranged below the cooling plate, and the cooling unit of the refrigerator and the cooling plate are configured to be in direct thermal contact via a first metal heat conductive member. The low temperature thermal conductivity measuring device according to the above. The low-temperature thermal conductivity measuring device according to claim 2, further comprising a first metal auxiliary heat conductive member that directly brings the upper portion of the cooling plate and the cooling portion into direct thermal contact. The first aspect of claim 1, wherein the refrigerator is arranged above the cooling plate, and a second metal heat conductive member is provided to bring the cooling portion of the refrigerator into thermal contact with the upper end of the cooling plate. Low temperature thermal conductivity measuring device. To constitute the cooling means, a metal airtight container surrounding the GHP method measuring device is provided in the space inside the heat insulating airtight container.
A refrigerator is provided to cool the metal airtight container by heat conduction.
The low-temperature thermal conductivity measuring device according to claim 1, further comprising a first metal heat conductive member that directly brings the metal airtight container and the cooling plate into direct thermal contact. A first metal auxiliary heat conductive member that attaches the cooling part of the refrigerator to the lower surface of the metal airtight container and directly brings the bottom plate of the metal airtight container and the upper part of the cooling plate into direct thermal contact. The low temperature thermal conductivity measuring device according to claim 5, which is provided. The low-temperature thermal conductivity measuring device according to claim 5, wherein the cooling portion of the refrigerator is brought into contact with the ceiling plate portion of the metal airtight container and attached.

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