JP7332413B2 - Low temperature thermal conductivity measuring device - Google Patents

Description

According to the present invention, a pair of flat plates to be measured are arranged on both sides of a heating plate, and 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 for measuring the temperature of both the front and back sides and calculating the thermal conductivity of the flat plate to be measured based on the amount of heat applied and the measured temperature difference between the front and back sides is housed inside the adiabatic airtight container. and a low-temperature thermal conductivity measuring apparatus in which a cooling means for cooling the cooling plate to a low temperature of 0° C. or less is provided in the heat-insulating airtight container.

The GHP method measurement apparatus is defined by the measurement method of JIS A 1412-1. Specifically, a heating plate and a pair of cooling plates are suspended from above on a support frame so as to be movable in the plate thickness direction. , a pressing device in which a flat plate to be measured is sandwiched between a heating plate and a cooling plate, and a pair of flat plates to be measured and a pair of cooling plates are brought into contact with each other by moving the pair of flat plates to be measured and the pair of cooling plates, centering on the heating plate. A pair is provided on both outer sides of the direction.

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

Building material test information 12 '89 "Thermal conductivity measurement in the low range by GHP method"

In the above-described conventional low-temperature thermal conductivity measuring apparatus, 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 at cryogenic temperatures below 180°C.
Therefore, as shown in FIG. 5, there is an apparatus for vaporizing liquid helium (LHe) to lower the ambient temperature in a heat-insulating airtight container 5 formed of a vacuum heat-insulating container to a cryogenic region of about −268° C. or lower. However, in order to lower the atmospheric temperature in the heat-insulating airtight container 5 by evaporating liquid helium, a large amount of liquid helium must be consumed. There was a problem that it took a lot of time and effort for replenishment and storage, and moreover it cost a lot of money. A measurement unit containing the apparatus, 33, is an opening/closing lid provided with a heat insulating material for opening the upper portion of the heat-insulating airtight container so that the GHP method measuring apparatus can be taken out).

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a low-temperature thermal conductivity measuring apparatus which solves the above problems and which can cool the cooling plate of the GHP method measuring apparatus while suppressing the consumption of liquid nitrogen or helium.

In a first characteristic configuration of the present invention, a pair of flat plates to be measured are arranged on both sides of a heating plate, a pair of cooling plates are arranged on both outer sides of the pair of flat plates to be measured, and the pair of A GHP method measuring device for measuring the temperature of both the front and back surfaces of each flat plate to be measured and calculating the thermal conductivity of the flat plate to be measured based on the amount of heat given and the difference in temperature measured between the front and back surfaces is considered to be heat insulating. A low-temperature thermal conductivity measuring device, which is housed inside an airtight container and provided in the heat insulating airtight container for cooling the cooling plate to a low temperature of 0° C. or less, wherein the cooling means comprises the cooling means. a mechanical refrigerator for cooling the cooling plate of the GHP method measurement device in the inner space of the heat insulating airtight container, and the cooling plate is cooled from the cooling part of the mechanical refrigerator through a heat conducting member is in direct thermal contact with

According to the first characteristic configuration of the present invention, the cooling means is provided with a mechanical refrigerator for cooling the cooling plate of the GHP method measurement apparatus in the inner space of the heat insulating airtight container, Direct thermal contact of the cold plate of the mechanical refrigerator via a heat conduction member suppresses the consumption of liquid nitrogen or helium, and allows the cold plate of the GHP measuring device to be easily cooled. can.

According to a second characteristic configuration of the present invention, the mechanical refrigerator is arranged below the cooling plate, and the cooling portion of the mechanical refrigerator and the cooling plate are used as the heat conducting member and are made of a first metal. The point is that direct thermal contact is possible via a heat conducting member.

According to the second characteristic configuration of the present invention, by arranging the mechanical refrigerator below the cooling plate, the GHP method measurement device equipped with the cooling plate can be easily assembled into the heat insulating airtight container. In addition, the cooling part of the mechanical refrigerator and the cooling plate are brought into direct thermal contact with each other by the first metal heat-conducting member, so that cold heat from the cooling part of the mechanical refrigerator is 1. Heat is efficiently transferred to the cooling plate through the metal heat-conducting member with little heat loss.

A third characteristic configuration of the present invention resides in that a first metal auxiliary heat conduction member is provided as the heat conduction member for bringing 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 during heat transfer. Cold heat from the cooling portion can be directly transferred to the upper portion of the cooling plate through the cooling plate, making it easier to uniformly cool the cooling plate from top to bottom.
Therefore, it is possible to improve the measurement accuracy of the thermal conductivity of the flat plate of the object to be measured.

In a fourth characteristic configuration of the present invention, the mechanical refrigerator is arranged above the cooling plate, and the heat conduction section is arranged such that the cooling portion of the mechanical refrigerator and the upper end portion of the cooling plate are in thermal contact with each other. A second metal heat-conducting member is provided as a member.

According to the fourth characteristic configuration of the present invention, the mechanical refrigerator is arranged above the cooling plate, and the heat dissipating portion of the mechanical refrigerator is brought into thermal contact with the upper end of the cooling plate. By providing the second metal heat-conducting member as a heat-conducting member, it is possible to directly transfer heat from the upper part of the cooling plate through the second metal heat-conducting member to cool the mechanical refrigerator, and the cooling plate is more heated from the upper part to the lower part. Cooling to a uniform temperature can improve the accuracy of thermal conductivity measurement.

A fifth characteristic configuration of the present invention is that the cooling means is configured by providing a metal airtight container surrounding the GHP method measurement apparatus in the inner space of the heat insulating airtight container, and the metal airtight container A mechanical refrigerator for cooling by heat conduction is provided, and a first metal heat conduction member is provided as the heat conduction member for bringing the metal airtight container and the cooling plate into direct thermal contact.

According to the fifth characteristic configuration of the present invention, a metal airtight container is provided to surround the GHP method measurement apparatus in the inner space of the heat insulating airtight container, and the metal airtight container is cooled by heat conduction. The cooling plate is directly cooled by the first metal heat-conducting member by providing a first metal heat-conducting member as the heat-conducting member that directly thermally contacts the metal airtight container and the cooling plate. and can be lowered to a lower temperature more easily.
In addition, the metal airtight container surrounding the GHP method measurement device can be evacuated, for example, by evacuating the space between the adiabatic airtight container and the metal airtight container to block heat from entering from the outside. If the internal space of the container is filled with a heat exchange refrigerant gas, the cooling plate of the GHP measurement apparatus can be efficiently cooled through the refrigerant gas.
In addition, the internal space of the metal airtight container can be evacuated or filled with gas (nitrogen, oxygen, helium, argon, hydrogen, etc.) at any pressure to measure thermal conductivity with high accuracy in various atmospheres. possible and possible.

In a sixth characteristic configuration of the present invention, the cooling part of the mechanical refrigerator is attached in 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 directly connected. A first metallic auxiliary heat conducting member is provided for thermal contact.

According to the sixth characteristic configuration of the present invention, the mechanical 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-conducting member, and the upper part of the cooling plate is cooled via the first metallic auxiliary heat-conducting member, and as a result, the cooling plate can be cooled substantially uniformly from top to bottom.

A seventh characteristic configuration of the present invention resides in that the cooling part of the mechanical refrigerator is mounted in contact with the ceiling plate part of the metal airtight container.

According to the seventh characteristic configuration of the present invention, the metal airtight container is preferentially cooled at the ceiling plate portion, so that the upper internal space of the metal airtight container has an internal atmosphere having a higher temperature than the lower part. Even if the gas accumulates, the internal atmospheric gas is cooled by the preferentially cooled metal airtight upper wall, allowing the cooling plate to be cooled more uniformly, resulting in a low-temperature thermal conductivity measuring device. can improve the measurement accuracy of

It is a longitudinal front view of the present invention. It is a front view of the principal part (GHP method measuring device). 1 is a cross-sectional plan view of the present invention; FIG. (a) is a first metal heat conduction member, (b) is a first bottom plate, and (c) is a plan view in which the first metal heat conduction member is erected and attached to the first bottom plate. It is a longitudinal front view of a conventional example. It is a longitudinal front view of another embodiment. It is a longitudinal front view of another embodiment. It is a longitudinal front view of another embodiment. It is a longitudinal front view of another embodiment. It is a longitudinal front view of another embodiment. It is a longitudinal front view of another embodiment.

An embodiment of the present invention will be described below with reference to the drawings.
As shown in FIGS. 1 to 4, a pair of flat plates 2 to be measured are arranged on both sides of a heating plate 1, and a pair of cooling plates 3 are arranged on both outer sides of the pair of flat plates 2 to be measured, The GHP method measuring device 4 for measuring the temperature of the front and back surfaces of each of the pair of flat plates 2 to be measured and calculating the thermal conductivity of the flat plate 2 to be measured based on the measured temperature difference between the front and back surfaces is used as a heat insulator. A cooling means for cooling the cooling plate 3 to a low temperature of 0° C. or below is provided in the heat-insulating airtight container 5 .

[First Embodiment]
In order to constitute the cooling means, a metal airtight container 6 is provided to surround the GHP method measurement device 4 in the inner space of the heat insulating airtight container 5, and a refrigerator 7 is provided to cool the metal airtight container 6 by heat conduction. A first metal heat-conducting member 8 is provided to bring the metal airtight container 6 and the cooling plate 3 into direct thermal contact.

Cooling by the refrigerator 7 is performed at a temperature called a cryogenic temperature below the boiling point of liquid air, particularly to a region below liquid helium (approximately -268°C). A refrigerator using a cycle) is used.

As shown in FIGS. 1 to 4, the GHP method measuring apparatus 4 supports a heating plate 1 and a pair of cooling plates 3 on a support frame 15 so as to be movable in the plate thickness direction. and a pair of cooling plates 3, and the pair of flat plates 2 to be measured and the pair of cooling plates 3 are brought into close contact with each other with the heating plate 1 as the center. 16 are provided on both outer sides in the plate thickness direction.
The grounding portion 15A of the support frame 15 is attached to the first bottom plate 17 made of copper with a thickness of 10 mm (FIGS. 4B and 2), and an anchor plate made of copper with a thickness of 3 mm is attached to the first bottom plate 17. The (first metal heat conduction member 8) is provided so as to be vertically mounted (FIG. 4(c)), and the anchor plate is provided with a connection portion 19 (bolt insertion hole) with the cooling plate 3 at the top, A long hole 20 for bolt insertion that can be connected to the first bottom plate 17 is provided in the lower end portion 8A along the movement direction of the cooling plate 3, and a bolt insertion hole 21 corresponding to the long hole 20 is provided on the first bottom plate. 17 (FIGS. 4A, 4B, and 4C).

As shown in FIG. 1, the first bottom plate 17 is fixed to the container bottom plate 24 with bolts, and the top surface of the container bottom plate 24 is attached with the first cover portion 22 surrounding the GHP method measuring apparatus 4. , the container bottom plate 24 and the first cover portion 22 constitute the metal airtight container 6 whose interior can be airtight.
A GM refrigerator is attached to the lower surface of the container bottom plate 24 so as to be in contact with its two-stage cooling section 23A (the second cooling section 23 having a two-stage expansion chamber provided therein).
Therefore, the cold heat from the GM refrigerator is directly transferred from the cooling section 23 of the refrigerator 7 to the cooling plate 3 via the metal airtight container 6 and the first metal heat-conducting member 8 .

As shown in FIG. 1, a radiation shield container 25 is provided to further surround the metal airtight container 6, and a second bottom plate 26 below the radiation shield container 25 is provided with a first-stage cooling section 23B (first cooling unit) of the GM refrigerator. The first-stage expansion chamber of the cooling section 23 is provided in the interior thereof) is penetrated and connected so as to be in contact with each other.
Accordingly, the radiation shield container 25 is also cooled by heat conduction from the first-stage cooling section 23B.
The outer side of the metal airtight container 6 and the radiation shield container 25 is a shield layer member 27 called super insulation, which is made by laminating a sheet of aluminum vapor-deposited on a polyimide film, for heat insulation from radiation. is covered.

An aluminum outer airtight container 28 is provided to further surround the metal airtight container 6 and the radiation shield container 25 .
The radiation shield container 25 and the outer airtight container 28 constitute a heat-insulating airtight container 5 in which the GHP method measuring device 4 is accommodated.
The first space S1 inside the outer tank airtight container 28 and the second space S2 inside the radiation shielding container 25 are decompressed by a vacuum pump and placed in a vacuum insulation state at the time of thermal conductivity measurement. The introduction of heat is 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 its internal space, is filled with a specific gas and cools the cooling plate 3 via the filled gas, or heat conduction in the filled gas atmosphere. Rates can also be measured.
In addition, when the internal space of the metal airtight container 6 is filled with a specific gas having a heat exchange action, if the temperature of the cold heat from the cooling section 23 is equal to or higher than the freezing point of the filling gas, the filling gas acts as a heat exchange gas, cold heat is transmitted to the cooling plate 3, and there is an effect of further increasing the cooling efficiency.

In the above-described embodiment, the heat-insulating airtight container 5 is vacuum-insulated by depressurizing the inside of the outer tank airtight container 28 and the inner space of the radiation shield container 25. When the conductivity is measured in a low-temperature region where dew condensation and freezing of the outer airtight container 28 do not pose a problem, the container may be an insulated container containing a heat insulating material under normal pressure.
However, when it is necessary to increase the cooling capacity of the cooling section 23 of the refrigerator 7, the surroundings of the refrigerator 7 need to be highly heat-insulated by vacuum insulation or the like.

[Second embodiment]
As the cooling means, the cooling plate 3 is cooled by the refrigerator 7, and a first metal heat-conducting member 8 is provided for connecting the cooling plate 3 to the first bottom plate 17 of the metal airtight container 6 so that heat can be conducted. In addition, as shown in FIG. 6, it consists of 8 copper wires (for example, 20 copper wires with a diameter of 1 mm are bundled) that directly thermally contact the first bottom plate 17 and the upper part of the cooling plate 3. A first metallic auxiliary heat conducting member 29 is provided. As a result, the upper portion of the cooling plate 3 is also efficiently cooled, making it possible to measure thermal conductivity in a cryogenic region.

[Third Embodiment]
As shown in FIG. 6 may be attached in contact with the ceiling plate portion 18. The GHP method measurement 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 vacuum-insulated spaces, and inside the heat-insulating airtight container 5, a metal airtight container 6 surrounding the GHP method measurement device 4 is provided, and the freezer is frozen. The refrigerator 7 is arranged above the cooling plate 3 so that the cold heat from the cooling part 23 of the refrigerator 7 is directly conducted to the cooling plate 3, and the upper end of the cooling part 23 of the refrigerator 7 and the cooling plate 3 is arranged. A second metal heat conducting member 35 may be provided in direct thermal contact with the portion.

[Fifth Embodiment]
As shown in FIG. 9, the cold heat from the cooling part 23 of the refrigerator 7 is directly conducted to the cooling plate 3 without providing the metal airtight container 6 as shown in FIG. For example, the first metal heat-conducting member 8 such as the above-mentioned copper anchor plate is connected to the first bottom plate 17 (the grounding portion 15A of the support frame 15 of the GHP measurement device 4) connected to the cooling portion 23. ) and the lower part of the cooling plate 3 .
The GHP method measuring device 4 is accommodated inside a heat-insulating airtight container 5 provided with a vacuum layer.

As in FIG. 9, in the apparatus without the metal airtight container 6, in addition to the first metal heat conduction member, a first metal auxiliary heat conduction member 29 equivalent to the copper wire is provided on the first bottom plate. 17 and the upper part of the cooling plate 3 may be connected.

[Other embodiments]
Other embodiments will be described below.
In addition, in other embodiments below, the same reference numerals are given to the same members as in the above embodiment.
<1> The metal airtight container 6 surrounding the GHP method measurement device 4 is configured to be directly cooled by the refrigerator 7, but the cooling plate 3 is cooled without providing a metal heat-conducting member. , cooling (indirect cooling) by a gas having a heat exchanging action filled in the metal airtight container 6 may be used.
<2> Instead of the GM refrigerator, other mechanical refrigerators (for example, pulse tube refrigerators, etc.) can be used.
<3> The first metal heat-conducting member 8 and the first metal auxiliary heat-conducting member 29 may be made of metal other than copper, such as aluminum, as long as it has good heat conductivity. The shape may also be a plate shape or a shape other than a wire.
<4> Inside the heat-insulating airtight container 5, as shown in FIG. A storage container 31 for evaporating liquid nitrogen or liquid helium is provided in the internal space of the adiabatic airtight container 5 in such a manner that cold heat is directly conducted to the cooling plate 3 via 35 to lower the ambient temperature. In this case, the advantage of being able to reduce the amount of liquid nitrogen or helium used can be expected compared to the conventional device, and the combined use can increase the operating time. Advantages such as longer extension and less labor for replenishing cryogen can be expected.
<5> As shown in FIG. 11, the first space S1 between the outer tank airtight container 28 and the metal airtight container 6 is formed in a vacuum insulation space, and the GHP method measurement device 4 is placed inside the heat insulating airtight container 5. may be provided. In this case, a single-stage refrigerator may be provided as the refrigerator. Also, a pattern without the container 25 in FIG. 1 may be used in a two-stage GM refrigerator.

As described above, reference numerals are used for convenience of comparison with the drawings, but such entries do not limit the present invention to the configurations shown in the attached drawings. Moreover, it is a matter of course that the present invention can be embodied in various modes without departing from the gist of the present invention.

REFERENCE SIGNS LIST 1 heating plate 2 flat plate of object to be measured 3 cooling plate 4 GHP method measuring device 5 heat insulating airtight container 6 metal airtight container 7 mechanical refrigerator 8 first metal heat conducting member 23 cooling part 29 first metal auxiliary heat Conductive member 35 Second metal thermally conductive member

Claims (7)

Place a pair of flat plates to be measured on both sides of the heating plate,
Disposing a pair of cooling plates on both outer sides of the pair of flat plates of the object to be measured,
A GHP measuring device for measuring the temperature of both the front and back surfaces of each of the pair of flat plates to be measured, and calculating the thermal conductivity of the flat plate to be measured based on the amount of heat given and the difference in temperature measured between the front and back surfaces. , a low-temperature thermal conductivity measuring device that is housed inside an adiabatic airtight container and provided in the adiabatic airtight container with cooling means for cooling the cooling plate to a low temperature of 0 ° C. or less,
The cooling means is provided with a mechanical refrigerator for cooling the cooling plate of the GHP method measurement apparatus in the inner space of the heat insulating airtight container, and heat is transferred from the cooling part of the mechanical refrigerator. A low-temperature thermal conductivity measuring device in direct thermal contact with the cooling plate via a member. The mechanical refrigerator is arranged below the cooling plate, and the cooling plate and the cooling part of the mechanical refrigerator can be directly thermally contacted with each other as the heat conducting member through a first metallic heat conducting member. 2. The low-temperature thermal conductivity measuring device according to claim 1, wherein 3. The low-temperature thermal conductivity measuring device according to claim 2, wherein a first metallic auxiliary heat-conducting member is provided as said heat-conducting member for bringing the upper portion of said cooling plate and said cooling portion into direct thermal contact. The mechanical refrigerator is arranged above the cooling plate, and a second metal heat-conducting member is provided as the heat-conducting member for thermally contacting the cooling part of the mechanical refrigerator and the upper end of the cooling plate. 2. The low-temperature thermal conductivity measuring device according to claim 1, further comprising: A metal airtight container surrounding the GHP method measurement device in the inner space of the heat insulating airtight container is provided to constitute the cooling means,
A mechanical refrigerator is provided for cooling the metal airtight container by heat conduction,
2. The low-temperature thermal conductivity measuring device according to claim 1, wherein a first metal heat-conducting member is provided as said heat-conducting member for directly thermally contacting said metal airtight container and said cooling plate. A first metal auxiliary heat conduction device in which the cooling part of the mechanical refrigerator is attached in 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. 6. The low-temperature thermal conductivity measuring device according to claim 5, further comprising a member. 6. The low-temperature thermal conductivity measuring device according to claim 5, wherein the cooling part of the mechanical refrigerator is mounted in contact with the ceiling plate part of the metal airtight container.

Images