Cryogenic heat transfer tester

Abstract

A cryogenic heat transfer tester according to an embodiment of the present invention is a heat transfer tester for measuring the thermal insulation performance of a specimen in a cryogenic and high vacuum environment. The cryogenic heat transfer tester may comprise: a first chamber; a second chamber which is located in the first chamber and in which the specimen is seated; a cryopump extending through and connected to the first chamber and maintaining the inside of the first chamber in a vacuum state; a cryogenic refrigerator having a displacer extending through the first chamber and connected to the second chamber, the cryogenic refrigerator being configured to cool the second chamber through a cold head; a gas supply control unit connected to the first chamber to control the supply of gas into the first chamber; a jig unit including a heater and movable toward the specimen through the first chamber and the second chamber to control the temperature of the specimen by using the heater; and a sensor unit for detecting changes inside the first chamber and the second chamber.

Description

Cryogenic heat transfer tester

[0001] The present invention relates to an ultra-low temperature heat transfer tester.

[0002] Unless otherwise indicated in this specification, the contents described in this identification item are not prior art for the claims of this application, and are not recognized as prior art simply because they are described in this identification item.

[0003] Generally, a liquefied gas storage device consists of a double-walled structure comprising an inner container for storing liquefied gas and an outer container that maintains the temperature of the liquefied gas stored in the inner container. The space between the inner and outer containers is filled with thermal insulation powder, and the structure is designed to minimize heat intrusion by maintaining a vacuum, thereby suppressing the evaporation of the liquefied gas as much as possible.

[0004] For such liquefied gas storage devices, the thermal insulation performance between the outer and inner containers is critical. Furthermore, since the vacuum level between the outer and inner containers changes over time due to internal outgasing, it is necessary to test the performance of the insulation material in response to changes in vacuum level.

[0005] In addition, with the recent increase in interest in hydrogen utilization, tests for analyzing the stability of equipment using liquid hydrogen are required. Accordingly, to measure the thermal conductivity at the boiling point of liquid hydrogen, 20K, a test environment is required where the temperature at the bottom of the specimen is 20K and the temperature at the top of the specimen is 300K.

[0006] The present invention aims to solve the above-mentioned problems by providing a heat transfer tester that maintains the internal state of the first chamber in a vacuum state using a cryopump connected to the first chamber, cools the specimen through a cryogenic refrigerator, and detects changes inside the first chamber and the second chamber through a sensor unit to calculate the heat flow rate and thermal conductivity coefficient of the specimen.

[0007] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0008] A cryogenic heat transfer tester according to one embodiment of the present invention may include: a first chamber; a second chamber located within the first chamber and having the specimen placed therein; a cryo pump connected through the first chamber and maintaining the interior of the first chamber in a vacuum state; a cryogenic refrigerator in which a displacer passes through the first chamber and is connected to the second chamber, and which cools the second chamber through a cold head; a gas supply control unit connected to the first chamber and controlling the supply of gas supplied into the first chamber; a jig unit including a heater and capable of moving toward the specimen by passing through the first chamber and the second chamber to control the temperature of the specimen using the heater; and a sensor unit for detecting changes inside the first chamber and the second chamber.

[0009] In one embodiment, the sensor unit may include at least one temperature sensor disposed inside the second chamber and monitoring the internal temperature of the second chamber; a heat flux sensor disposed in the jig unit and monitoring the heat flux transmitted to the specimen; and a gauge unit monitoring the pressure of the first chamber.

[0010] In one embodiment, a control unit that controls the operation of the cryo pump, the cryogenic refrigerator, the heater, and the jig may be further included.

[0011] In one embodiment, the control unit can move the jig unit toward the specimen so that the heater and the specimen come into contact when the specimen is placed in the second chamber.

[0012] In one embodiment, the control unit may operate the cryo pump to form a high vacuum in the first chamber, and when the pressure in the first chamber is less than a preset first pressure value, the cryogenic refrigerator may be operated.

[0013] In one embodiment, the control unit monitors the pressure of the first chamber through the gauge unit and can control the pressure value of the first chamber by opening or closing the first gate valve of the cryo pump or by using the supply control unit.

[0014] In one embodiment, the control unit may operate the second gate valve of the cryo pump when replacing the specimen to narrow the pressure gap between the pressure inside the first chamber and the outside.

[0015] In one embodiment, the control unit can maintain the temperature of the specimen by operating the heater when the temperature of the specimen cooled through the cryogenic refrigerator reaches a preset first temperature value.

[0016] In one embodiment, the control unit can measure the heat flow rate, thermal conductivity, and temperature of the specimen through the temperature sensor and the heat flux sensor.

[0017] In one embodiment, the outer surface of the first chamber and the second chamber may be surrounded by epoxy.

[0018] According to one embodiment of the present invention, the cryo-low temperature heat transfer tester can eliminate vacuum fluctuation factors that may occur when the temperature rises at cryogenic temperatures by connecting a cryo-pump to the first chamber, and can cool the temperature of the specimen to 20K or lower by connecting a cryo-low temperature refrigerator to the second chamber.

[0019] In addition, changes inside the first chamber and the second chamber can be detected through the sensor unit to calculate the heat flow rate and thermal conductivity coefficient of the specimen.

[0020] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below.

[0021] FIG. 1 is a perspective view of an ultra-low temperature heat transfer tester according to one embodiment of the present invention.

[0022] FIG. 2 is a perspective view of an ultra-low temperature heat transfer tester according to one embodiment of the present invention, viewed from another side.

[0023] FIG. 3 is a diagram showing the interior of a first chamber in an ultra-low temperature heat transfer tester according to one embodiment of the present invention.

[0024] FIG. 4 is a block diagram showing an ultra-low temperature heat transfer tester according to one embodiment of the present invention.

[0025] FIG. 5 is a block diagram showing a sensor section in an ultra-low temperature heat transfer tester according to one embodiment of the present invention.

[0026] Embodiments of the present invention are described below in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0027] Throughout the specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, throughout the specification, when a part is described as "connected" to another part, this includes not only cases where they are directly connected, but also cases where they are connected with an intermediate component interposed, and cases where they are electrically connected with an intermediate element. Moreover, throughout the specification, when a component is described as being "on" another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components. Additionally, expressions such as "first," "second," etc., used in this specification may modify various components regardless of order and / or importance; they are used merely to distinguish one component from another and do not limit those components, nor do they necessarily refer to different components. For example, "first direction" and "second direction" may refer to the same direction or different directions.

[0028] FIG. 1 is a perspective view of an ultra-low temperature heat transfer tester (10) according to one embodiment of the present invention, FIG. 2 is a perspective view of an ultra-low temperature heat transfer tester (10) according to one embodiment of the present invention viewed from another side, FIG. 3 is a drawing showing the interior of a first chamber (100) in an ultra-low temperature heat transfer tester (10) according to one embodiment of the present invention, and FIG. 4 is a block diagram showing an ultra-low temperature heat transfer tester (10) according to one embodiment of the present invention.

[0029] Referring to FIGS. 1 to 4, an ultra-low temperature heat transfer tester (10) according to one embodiment of the present invention may include a first chamber (100), a second chamber (200), a cryo pump (300), a cryogenic refrigerator (400), a gas supply control unit (500), a jig unit (600), and a sensor unit (700).

[0030] A cryogenic heat transfer tester (10) according to one embodiment of the present invention conducts a test after cooling a specimen (20) placed inside, and can measure the thermal conductivity coefficient of the specimen (20) at a low temperature.

[0031] The first chamber (100) has a first opening / closing part formed on one side so that a specimen (20) can be placed inside or removed.

[0032] For example, a part of the first opening / closing section may be made of a transparent material such as tempered glass or plastic so that the specimen (20) can be observed during a heat transfer test.

[0033] As shown in FIGS. 1 to 3, the first chamber (100) may have an opening formed so that a displacer (410) and a cold head (420) of a cryogenic refrigerator (400) are inserted and coupled at the bottom, a part of a jig part (600) is inserted and coupled at the top, and a part of a cryo pump (300) is inserted and coupled on the other side.

[0034] The outer surface of the first chamber (100) may be surrounded by epoxy to shield against the inflow of a heat source from the outside.

[0035] In one embodiment, the second chamber (200) is located within the first chamber (100), and a specimen (20) can be placed inside.

[0036] For example, as shown in FIG. 3, the second chamber (200) has a second opening / closing part formed on one side, and the lower part of the second chamber (200) can be in contact with the cold head (420) of the cryogenic refrigerator (400) to cool the second chamber (200). In addition, a part of the jig part (600) can be inserted into the upper part of the second chamber (200) to be configured to be in contact with the specimen (20).

[0037] The second opening / closing part may be formed at a position corresponding to the first opening / closing part to facilitate the replacement of the specimen (20) placed inside the second chamber (200).

[0038] A portion of the second opening / closing part may be made of a transparent material such as reinforced glass or plastic so that the specimen (20) can be observed during a heat transfer test, and the outer surface of the second chamber (200) may be covered with epoxy to shield against the inflow of a heat source from the outside, but the part in contact with the second chamber (200) and the cryogenic refrigerator (400) may not be covered with epoxy.

[0039] In one embodiment, the cryo pump (300) is connected through the first chamber (100) and can maintain the interior of the first chamber (100) in a vacuum state.

[0040] For example, the cryo pump (300) can be connected through the first chamber (100) to maintain the interior of the first chamber (100) in a high vacuum state.

[0041] The cryo pump (300) is a pump that reduces the internal pressure of the first chamber (100) and can eliminate vacuum fluctuation factors that may occur when the temperature rises from cryogenic temperatures.

[0042] The ultra-low temperature heat transfer tester (10) may further include a cryopump (300) and a roughing pump (not shown) connected to the first chamber (100).

[0043] A roughing pump (not shown) is used for initial vacuuming of the vacuum system and can be installed for rapid evacuation of the cryo pump (300) and the first chamber (100).

[0044] For example, a low vacuum can be formed in the first chamber (100) using a roughing pump (not shown), and when a low vacuum is formed in the first chamber (100), a cryo pump (300) can be operated to form a high vacuum in the first chamber (100).

[0045] In one embodiment, the cryogenic refrigerator (400) is connected to the second chamber (200) through the first chamber (100) by a displacer (410), and can cool the second chamber (200) through a cold head (420).

[0046] The cryogenic refrigerator (400) may be a GM refrigerator that generates cooling capacity by a GM (Gifford-McMahon) cycle using helium gas as the working fluid.

[0047] For example, as shown in FIG. 3, the cryogenic refrigerator (400) can transfer heat to a specimen (20) by connecting a displacer (410) through the first chamber (100) and a cold head (420) connected to the end of the displacer (410) to a cold plate (not shown) that contacts the bottom of the second chamber (200).

[0048] The cold head (420) of the cryogenic refrigerator (400) may be composed of multiple parts to increase the cooling rate of the specimen (20) placed inside the second chamber (200).

[0049] In one embodiment, the gas supply control unit (500) is connected to the first chamber (100) and can control the supply of gas supplied into the first chamber (100).

[0050] For example, when the interior of the first chamber (100) is formed into a high vacuum state through the cryo pump (300), gas can be supplied into the interior of the first chamber (100) through the gas supply control unit (500) to maintain the vacuum level desired by the user. At this time, the gas supplied into the interior of the first chamber (100) may be nitrogen, but is not limited thereto.

[0051] In one embodiment, the jig portion (600) includes a heater (610), and can move toward the specimen (20) by passing through the first chamber (100) and the second chamber (200) to control the temperature of the specimen (20) using the heater (610).

[0052] For example, as shown in FIGS. 1 to 3, the jig portion (600) is formed on the upper part of the first chamber (100) and penetrates the first chamber (100) and the second chamber (200), and moves toward and contacts the specimen (20), thereby causing the specimen (20) to be in close contact with the second chamber (200), so that the heat transfer efficiency from the cryogenic refrigerator (400) to the specimen (20) can be increased.

[0053] Meanwhile, a heater (610) is included at the end of the jig part (600) that contacts the specimen (20) to control the temperature of the specimen (20).

[0054] For example, by using a heater (610) that is in contact with the upper part of the specimen (20) to control the temperature of the specimen (20), the thermal conductivity at a desired temperature can be measured.

[0055] FIG. 5 is a block diagram showing a sensor unit (700) in an ultra-low temperature heat transfer tester (10) according to one embodiment of the present invention.

[0056] Referring to FIGS. 4 and 5, the sensor unit (700) can detect changes inside the first chamber (100) and the second chamber (200).

[0057] For example, the sensor unit (700) can detect internal changes in the first chamber (100) and the second chamber (200), and thereby control the operation of the cryo pump (300), cryogenic refrigerator (400), heater (610), and jig unit (600) according to the internal changes in the first chamber (100) and the second chamber (200) through the control unit (800) to be described later.

[0058] In one embodiment, the sensor unit (700) may include a temperature sensor (710), a heat flux sensor (720), and a gauge unit (730).

[0059] A temperature sensor (710) is placed inside the second chamber (200) and can monitor the internal temperature of the second chamber (200), a heat flux sensor (720) is placed in the jig part (600) and can monitor the heat flux transmitted to the specimen (20), and a gauge unit (730) can monitor the pressure of the first chamber (100).

[0060] As described above, the control unit (800) can control the operation of the cryo pump (300), cryogenic refrigerator (400), heater (610) and jig unit (600).

[0061] The control unit (800) can move the jig unit (600) toward the specimen (20) so that the heater (610) and the specimen (20) come into contact when the specimen (20) is placed in the second chamber (200).

[0062] For example, when the specimen (20) is placed in the second chamber (200), the control unit (800) moves the jig unit (600) toward the specimen (20) so that the heater (610) and the specimen (20) come into contact, thereby bringing the specimen (20) into close contact with the second chamber (200) and increasing the heat transfer efficiency from the cryogenic refrigerator (400) to the specimen (20).

[0063] The control unit (800) can operate the cryo pump (300) to form a high vacuum in the first chamber (100), and can operate the cryogenic refrigerator (400) when the pressure in the first chamber (100) is less than a preset first pressure value.

[0064] At this time, the control unit (800) can operate the roughing pump first, as described above, before operating the cryo pump (300).

[0065] For example, a roughing pump is installed to rapidly exhaust the cryo pump (300) and the first chamber (100) to form a low vacuum within the first chamber (100), and when a low vacuum is formed within the first chamber (100), the cryo pump (300) can be operated to form a high vacuum within the first chamber (100).

[0066] The control unit (800) monitors the pressure of the first chamber (100) through the gauge unit (730) and can control the pressure value of the first chamber (100) by opening and closing the first gate valve (310) of the cryo pump (300) or by using the gas supply control unit (500).

[0067] For example, when the control unit (800) forms a high vacuum inside the first chamber (100) through the cryo pump (300), it can supply gas into the inside of the first chamber (100) through the gas supply control unit (500) or open and close the first gate valve (310) to maintain the vacuum level desired by the user.

[0068] The control unit (800) can operate the cryogenic refrigerator (400) when the pressure inside the first chamber (100) is less than a preset first pressure value.

[0069] For example, the control unit (800) can operate the cryogenic refrigerator (400) when the pressure inside the first chamber (100) is less than a preset first pressure value through the cryo pump (300). After a certain amount of time has passed, the temperature of the specimen (20) can be cooled to 10K by the cryogenic refrigerator (400).

[0070] At this time, the cryogenic refrigerator (400) can be operated even when the pressure inside the first chamber (100) becomes less than a preset first pressure value by using a roughing pump connected to the cryo pump (300) and the first chamber (100). For example, if a vacuum is formed by using a roughing pump (not shown) to evacuate the internal pressure of the cryo pump (300) to less than a preset first pressure value, the cryogenic refrigerator (400) can be operated, and a high vacuum can be formed inside the first chamber (100) using the cryo pump (300).

[0071] In one embodiment, the control unit (800) can maintain the temperature of the specimen (20) by operating the heater (610) when the temperature of the specimen (20) cooled through the cryogenic refrigerator (400) reaches a preset first temperature value.

[0072] For example, the control unit (800) can operate a heater (610) that contacts the upper part of the specimen (20) after the lower part of the specimen (20) has been cooled to 10K by the cryogenic refrigerator (400) to maintain the upper part of the specimen (20) at a temperature desired by the user.

[0073] In one embodiment, the control unit (800) can measure the heat flow rate, thermal conductivity, and temperature of the specimen (20) through the temperature sensor (710) and the heat flux sensor (720).

[0074] For example, the control unit (800) can measure the heat flow rate of the specimen (20) through the heat flow sensor (720), and can measure the lower temperature and upper temperature of the specimen (20) through the temperature sensor (710), and can obtain the thermal conductivity coefficient through the measured heat flow rate, the lower temperature of the specimen (20), and the upper temperature of the specimen (20).

[0075] Here, the formula for calculating the thermal conductivity (K) is as follows.

[0076] <Mathematical Formula 1>

[0077] Q = K*(dT / t)

[0078] Here, Q is the heat flow rate, K is the thermal conductivity, dT is the temperature difference between the upper and lower parts of the specimen (20) (T₂ - T₁), and t is the thickness of the specimen (20).

[0079] Looking at the above mathematical formula 1, the thermal conductivity can be measured through the heat flow measured by the heat flow sensor and the temperature difference between the upper and lower parts of the specimen (20), that is, the difference between the lower temperature of the specimen (20) cooled by the cryogenic refrigerator (400) and the upper temperature of the specimen (20) heated by the heater (610).

[0080] In one embodiment, the control unit (800) can operate the second gate valve (320) of the cryo pump (300) when replacing the specimen (20) to narrow the pressure gap between the inside of the first chamber (100) and the outside.

[0081] For example, the control unit (800) can make it easier to replace the specimen (20) by controlling the opening and closing of the second gate valve (320) placed between the cryo pump (300) and the first chamber (100) as shown in FIG. 2, thereby narrowing the gap between the internal pressure of the first chamber (100) and the external pressure when replacing the specimen (20).

[0082] As described above, in an embodiment of the present invention, the cryo-low temperature heat transfer tester (10) can eliminate vacuum fluctuation factors that may occur when the temperature rises at cryogenic temperatures by connecting a cryo pump (300) to the first chamber (100), and can cool the temperature of the specimen (20) to 20K or lower by connecting a cryo-low temperature refrigerator (400) to the second chamber (200).

[0083] In addition, changes inside the first chamber (100) and the second chamber (200) can be detected through the sensor unit (700) to calculate the heat flow rate and thermal conductivity coefficient of the specimen (20).

[0084] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0085] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

1. In a heat transfer tester for measuring the thermal insulation performance of a specimen in an ultra-low temperature, high vacuum environment, First chamber; A second chamber located within the first chamber and having the specimen placed thereon; A cryo pump that is connected through the first chamber and maintains the interior of the first chamber in a vacuum state; A cryogenic refrigerator in which a displacer penetrates the first chamber and is connected to the second chamber, and cools the second chamber through a cold head; A gas supply control unit connected to the first chamber and controlling the supply of gas supplied into the first chamber; A jig portion including a heater and movable toward the specimen by penetrating the first chamber and the second chamber to control the temperature of the specimen using the heater; and A cryogenic heat transfer tester comprising: a sensor unit for detecting changes inside the first chamber and the second chamber.

2. In Paragraph 1, The sensor unit above is, At least one temperature sensor disposed inside the second chamber and monitoring the internal temperature of the second chamber; A heat flux sensor disposed in the above jig portion and monitoring the heat flux transmitted to the specimen; and A cryogenic heat transfer tester comprising a gauge unit for monitoring the pressure of the first chamber.

3. In Paragraph 2, A cryogenic heat transfer tester further comprising a control unit that controls the operation of the cryo pump, the cryogenic refrigerator, the heater, and the jig unit.

4. In Paragraph 3, The above control unit is, A cryogenic heat transfer tester that moves the jig portion toward the specimen so that the heater and the specimen come into contact when the specimen is placed in the second chamber.

5. In Paragraph 3, The above control unit is, A cryogenic heat transfer tester that operates the cryo pump to form a high vacuum in the first chamber, and operates the cryogenic refrigerator when the pressure in the first chamber is less than a preset first pressure value.

6. In Paragraph 3, The above control unit is, A cryogenic heat transfer tester that monitors the pressure of the first chamber through the gauge unit and controls the pressure value of the first chamber using the opening and closing of the first gate valve of the cryo pump or the gas supply control unit.

7. In Paragraph 3, The above control unit is, A cryogenic heat transfer tester that, when replacing the above specimen, operates the second gate valve of the above cryo pump to narrow the pressure gap between the inside of the first chamber and the outside.

8. In Paragraph 3, The above control unit is, A cryogenic heat transfer tester that operates a heater to maintain the temperature of a specimen when the temperature of the specimen, cooled through the cryogenic refrigerator, reaches a preset first temperature value.

9. In Paragraph 3, The above control unit is, A cryogenic heat transfer tester that measures the heat flow rate, thermal conductivity, and temperature of the specimen through the temperature sensor and the heat flux sensor.

10. In Paragraph 1, A cryogenic heat transfer tester in which the outer surfaces of the first chamber and the second chamber are surrounded by epoxy.

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