Device and method for testing heat insulation performance of large-volume low-temperature storage tank with air cooling screen

Abstract

The invention provides a device and a method for testing the heat insulation performance of a large-volume low-temperature storage tank with an air cooling screen. According to the device, the bottom of an upper protection cavity is connected with the top of a test cavity through supporting pieces, the bottom of the test cavity is connected with the top of a lower protection cavity through supporting pieces, meanwhile, copper screens are introduced between the upper protection cavity and the test cavity and between the test cavity and the lower protection cavity, and therefore wrapping of multiple layers of heat insulation materials between the test cavity and the protection cavities is facilitated; by introducing the copper screen, parasitic heat leakage from the top plate and the bottom plate of the test cavity is effectively avoided, and the accuracy of a test result is improved. The device and the method can realize the determination of the leakage heat flow of the large-volume low-temperature storage tank and the apparent heat conductivity coefficient of the thermal insulation material.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic liquefied gas storage and transportation technology, and relates to a device and method for testing the thermal insulation performance of a large-volume cryogenic storage tank with a gas-cooled shield. Background Technology

[0002] With the transformation of the global energy structure and the rapid growth in demand for clean energy, the storage and transportation technologies for cryogenic liquefied gases such as liquefied natural gas, liquid hydrogen, liquid nitrogen, and liquid helium have become crucial for the development of emerging industries. Large-capacity cryogenic storage tanks, as the core storage facilities for these cryogenic liquefied gases, rely on superior insulation performance for long-term, efficient, and safe operation. Currently, cryogenic storage tanks commonly employ passive insulation technologies such as vacuum multilayer insulation and hollow glass microspheres. To achieve lower medium evaporation losses and further improve economic efficiency and operational effectiveness, an advanced technological approach is to introduce a "gas-cooled screen" thermal management unit into the traditional passive insulation structure.

[0003] The gas-cooled shield utilizes the cryogenic gas evaporating from the storage tank, absorbing some of the transferred heat through its sensible heat change. The introduction of this structure transforms the storage tank's insulation system into a complex heat transfer system composed of high-vacuum multilayer insulation materials and the gas-cooled shield. In this system, the apparent thermal conductivity of the insulation material is no longer a fixed property; its performance strongly depends on the specific temperature boundary created by the gas-cooled shield. Therefore, accurately obtaining the comprehensive thermal performance of the insulation material under actual operating conditions coupled with the gas-cooled shield is a fundamental prerequisite for accurately predicting the overall insulation effect of the storage tank, optimizing the structural design and operating parameters of the gas-cooled shield, and ultimately achieving lean engineering design. Existing literature mainly uses evaporation calorimetry to evaluate the performance of insulation systems for small cryogenic storage tanks coupled with gas-cooled shields. Traditional small cryogenic storage tanks have significant theoretical limitations: when the insulation layer thickness and the test chamber radius are on the same order of magnitude, the heat transfer process is typical cylindrical conduction, and the influence of material thickness is unavoidable. However, in engineering practice, the diameter of the test chamber for cryogenic containers is generally 1-2 orders of magnitude larger than the material thickness. In this case, the thermal conduction behavior of the insulation structure approaches that of a flat plate thermal conductivity model. This size effect leads to model bias, making it difficult for traditional small cryogenic tanks to simulate the wrapping methods and insulation structure states in actual engineering applications. Consequently, the performance obtained in the laboratory differs significantly from that in engineering applications. Therefore, research and testing of large cryogenic tanks are necessary.

[0004] Chinese patent applications CN111307485A and CN120490209A both employ evaporative calorimetry to determine the apparent thermal conductivity of insulation materials. These two patent applications primarily consist of an upper protective chamber, a test chamber, and a lower protective chamber, with each chamber connected only by pipes. This is feasible for small-volume cryogenic storage tanks with a test chamber volume less than 20 L. However, for larger cryogenic storage tanks, welded steel pipes are required to support the test chamber and the lower protective chamber. To ensure sufficient welding space, the distance between the test chamber and the protective chamber needs to be controlled at approximately 100 mm. This prevents the protective chamber and test chamber from being seamlessly integrated when using multi-layer insulation materials. Furthermore, the connecting pipes make it difficult to effectively enclose the top and bottom plates of the test chamber with multi-layer insulation materials, leading to increased heat leakage in the interlayer space between the test chamber and the protective chamber, thus affecting the accuracy of the test results.

[0005] In summary, current technologies focus on research into small cryogenic storage tanks and rarely address gas-cooled shield structures. For large cryogenic storage tanks with gas-cooled shields, modifications to the interlayer space between the testing chamber and the protective chamber are required, and relevant research is currently lacking. Summary of the Invention

[0006] To address the problem in the prior art that the protective cavity and test cavity of a large cryogenic storage tank with an air-cooled screen cannot be integrated with multiple layers of insulation material, this invention provides a device and method for testing the insulation performance of a large-volume cryogenic storage tank with an air-cooled screen.

[0007] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a testing device for the thermal insulation performance of a large-volume cryogenic storage tank with a gas-cooled screen, comprising a sealed container, a vacuuming unit, a cryogenic liquid injection unit, an exhaust unit, and a data acquisition unit. The sealed container contains, from top to bottom, an upper protective chamber, a test chamber, and a lower protective chamber. The bottom of the upper protective chamber is connected to the top of the test chamber, and the bottom of the test chamber is connected to the top of the lower protective chamber, all via support members. The lower outer wall of the upper protective chamber is connected to the upper outer wall of the test chamber, and the lower outer wall of the test chamber is connected to the upper outer wall of the lower protective chamber, all via copper shields. The outer walls of the upper protective chamber, the test chamber, and the lower protective chamber, as well as the top of the upper protective chamber, the bottom of the lower protective chamber, and the outer wall of the copper shields, are all covered with heat-insulating material. An air-cooled shield is installed within the heat-insulating material on the outer wall of the test chamber. The vacuum pumping unit is used to evacuate the sealed cavity; the cryogenic liquid injection unit is used to inject cryogenic liquid into the upper protective cavity, the test cavity, and the lower protective cavity; the exhaust unit is used to exhaust the gas in the upper protective cavity, the test cavity, the lower protective cavity, and the air-cooled screen; the data acquisition unit is used to measure the flow rate of the volatile gas in the test cavity and the temperature of the outer wall of the inner insulation material of the air-cooled screen, the outer wall of the insulation material of the outer side of the air-cooled screen, the outer wall of the test cavity, and the outer wall of the air-cooled screen.

[0008] Preferably, an indium sheet is disposed between the lower outer wall of the upper protective cavity and the corresponding copper screen, and an indium sheet is disposed between the upper outer wall of the lower protective cavity and the corresponding copper screen.

[0009] Preferably, the contact length between the upper protective cavity and the corresponding copper screen along the height direction is not less than 50 mm; the contact length between the lower protective cavity and the corresponding copper screen along the height direction is not less than 50 mm.

[0010] Preferably, an insulating gasket is provided between the test chamber and the copper screen.

[0011] Preferably, the contact length between the test cavity and the copper screen along the height direction is no more than 10 mm.

[0012] Preferably, the copper screen has multiple holes along the horizontal direction.

[0013] Preferably, the cryogenic liquid injection unit includes a cryogenic liquid storage tank; the test chamber is connected to the cryogenic liquid storage tank via a pipe and a first gate valve installed on the pipe, the lower protection chamber is connected to the cryogenic liquid storage tank via a pipe and a second gate valve installed on the pipe, and the upper protection chamber is connected to the lower protection chamber via a pipe.

[0014] Preferably, the exhaust unit includes a high-altitude exhaust pipe, the upper protective chamber is connected to the high-altitude exhaust pipe through a pipe, the test chamber is connected to the high-altitude exhaust pipe through a pipe and a third gate valve, the pipe between the test chamber and the third gate valve is connected to the air-cooled screen through a fourth gate valve, and the air-cooled screen is connected to the high-altitude exhaust pipe through a pipe.

[0015] Secondly, the present invention provides a method for testing the insulation performance of a large-volume cryogenic storage tank with an air-cooled shield, comprising: The sealed cavity is evacuated to a preset vacuum level; Cryogenic liquid is injected into the upper protection chamber, the test chamber, and the lower protection chamber. The gas volatilized in the protection chamber and the lower protection chamber is discharged through the exhaust unit. The gas volatilized in the test chamber is discharged through the exhaust unit after passing through the gas-cooled screen. The flow rate of volatile gas in the test chamber and the temperatures of the outer walls of the insulation material, the test chamber, and the air-cooled screen are measured. After the flow rate of volatile gas in the test chamber stabilizes, the heat flow of the cryogenic storage tank and the apparent thermal conductivity of the insulation material are calculated based on the measurement results.

[0016] Preferably, the formula for calculating the heat flow leakage of the cryogenic storage tank is: (1) In the formula, m It is the mass flow rate of the volatile gas in the test chamber, kg / s; h fgIt is the latent heat of vaporization of cryogenic liquids, J / Kg; d i It is the outer diameter of the test chamber, in meters (m). l It is the height of the test chamber, in meters (m). The formula for calculating the apparent thermal conductivity of the insulation material inside the air-cooled screen is as follows: (2) In the formula, d 1 is the outer diameter of the insulation material inside the air-cooled screen, in meters (m). T 1 represents the temperature difference, in K, between the outer wall of the insulation material inside the air-cooled screen and the outer wall of the test chamber. The formula for calculating the apparent thermal conductivity of the outer insulation material of the air-cooled screen is as follows: (3) In the formula, d o It is the outer diameter of the insulation material on the outside of the air-cooled screen, in meters; d 2 is the outer diameter of the air-cooled screen, in meters (m). T 2 is the temperature difference between the outer wall of the insulation material on the outside of the air-cooled screen and the outer wall of the air-cooled screen, in K.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The insulation performance testing device for large-volume cryogenic storage tanks with air-cooled shields described in this invention is connected to the bottom of the upper protective chamber and the top of the test chamber, as well as to the bottom of the test chamber and the top of the lower protective chamber, by support members. Therefore, this device is suitable for testing the insulation performance of large-volume cryogenic storage tanks. Simultaneously, copper shields are introduced between the upper protective chamber and the test chamber, and between the test chamber and the lower protective chamber, facilitating the wrapping of multiple layers of insulation material between the test chamber and the protective chamber. The introduction of the copper shields effectively avoids parasitic heat leakage from the top and bottom plates of the test chamber, improving the accuracy of the test results. This invention can determine the heat flux leakage of large-volume cryogenic storage tanks and the apparent thermal conductivity of the insulation material. This device breaks through the size limitations of traditional calorimeters. Compared to the existing technology where small cryogenic storage tanks generally use test chambers with diameters on the order of 0.15-0.25 m, the cryogenic storage tank of this invention significantly improves the engineering applicability of the experimental model through scale expansion. Furthermore, since the diameter of the test chamber provides the greatest uncertainty, increasing the diameter of the test chamber is beneficial to improving accuracy.

[0018] Furthermore, indium sheets are provided between the lower outer wall of the upper protective cavity and the corresponding copper screen, and between the upper outer wall of the lower protective cavity and the corresponding copper screen. The addition of indium sheets ensures that the copper screen, the indium sheets, and the outer wall of the protective cavity are in close contact, thus avoiding the influence of contact thermal resistance.

[0019] Furthermore, the contact length between the copper screen and the upper and lower protective cavities in the height direction is more than 50 mm, ensuring that the upper and lower protective cavities provide sufficient cooling to the copper screen and avoid insufficient cooling causing the copper screen temperature to be too high, which would affect the measurement of heat leakage in the test cavity.

[0020] Furthermore, the contact length between the copper screen and the test cavity in the height direction is within 10 mm, and a high thermal resistance insulating gasket is added between them, which effectively suppresses the influence of the copper screen on the heat leakage of the test cavity.

[0021] Furthermore, the copper screen has holes to ensure a high vacuum inside, thus improving the insulation effect. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a large-volume cryogenic storage tank insulation performance testing device with an air-cooled screen, according to one embodiment of the present invention. Figure 2 This is a schematic diagram of a copper screen structure in one embodiment of the present invention.

[0024] In the diagram: 1—First gate valve; 2—Second gate valve; 3—Third gate valve; 4—Mass flow meter; 5—Cover plate; 6—Full flow gauge; 7—Molecular pump unit; 8—Upper protective chamber; 9—Fourth gate valve; 10—Support component; 11—Insulation gasket; 12—Air-cooled screen; 13—Test chamber; 14—Thermometer group; 15—Copper screen; 16—Lower protective chamber; 17—Indium sheet; 18—Insulation material; 19—Outer shell; 20—Hole. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0027] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0028] Furthermore, it should be noted that the terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. The terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In addition, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements.

[0029] like Figure 1 As shown, the thermal insulation performance testing device for a large-volume cryogenic storage tank with a gas-cooled screen according to the present invention includes a sealed container, a vacuum pumping unit, a cryogenic liquid injection unit, an exhaust unit, and a data acquisition unit. The sealed cavity inside the sealed container is provided with an upper protective cavity 8, a test cavity 13, and a lower protective cavity 16 arranged sequentially from top to bottom; the bottom of the upper protective cavity 8 and the top of the test cavity 13, as well as the bottom of the test cavity 13 and the top of the lower protective cavity 16, are connected by a support member 10; the lower outer wall of the upper protective cavity 8 and the upper outer wall of the test cavity 13, as well as the lower outer wall of the test cavity 13 and the upper outer wall of the lower protective cavity 16, are connected by a copper screen 15; the outer walls of the upper protective cavity 8, the test cavity 13, and the lower protective cavity 16, as well as the top of the upper protective cavity 8, the bottom of the lower protective cavity 16, and the outer wall of the copper screen 15, are all covered with heat insulation material 18, and an air-cooled screen 12 is provided in the heat insulation material of the outer wall of the test cavity 13; The vacuum pumping unit is used to evacuate the sealed cavity, so that a vacuum interlayer is formed between the upper protective cavity 8, the test cavity 13, the lower protective cavity 16 and the sealed cavity; the cryogenic liquid injection unit is used to inject cryogenic liquid into the upper protective cavity 8, the test cavity 13 and the lower protective cavity 16; the exhaust unit is used to exhaust the gas in the upper protective cavity 8, the test cavity 13, the lower protective cavity 16 and the air-cooled screen 12; the data acquisition unit is used to measure the flow rate of the volatile gas in the test cavity 13 and the temperature of the outer wall of the inner side insulation material 18 of the air-cooled screen 12, the outer side insulation material 18 of the air-cooled screen 12, the outer wall of the test cavity 13 and the outer wall of the air-cooled screen 12.

[0030] In this invention, the bottom of the upper protective cavity 8 is connected to the top of the test cavity 13, and the bottom of the test cavity 13 is connected to the top of the lower protective cavity 16, both via support members 10. Therefore, this device is suitable for testing the insulation performance of large-capacity cryogenic storage tanks (greater than 20L). Simultaneously, copper screens are introduced between the upper protective cavity 8 and the test cavity 13, and between the test cavity 13 and the lower protective cavity 16, facilitating the wrapping of multiple layers of insulation material between the test cavity and the protective cavity. Thus, the introduction of the copper screens effectively avoids parasitic heat leakage from the top and bottom plates of the test cavity, improving the accuracy of the test results. This invention can realize the determination of heat flow leakage from large-capacity cryogenic storage tanks and the apparent thermal conductivity of insulation materials.

[0031] In some embodiments of the present invention, an indium sheet is disposed between the lower outer wall of the upper protective cavity 8 and the corresponding copper screen 15, and an indium sheet is disposed between the upper outer wall of the lower protective cavity 16 and the corresponding copper screen 15. Indium, as a metal with high thermal conductivity and good ductility, ensures close contact between the copper screen, the indium sheet, and the outer walls of each protective cavity, thus avoiding the influence of contact thermal resistance.

[0032] In some embodiments of the present invention, the contact length between the upper protective cavity 8 and the corresponding copper screen 15 along the height direction is not less than 50 mm; the contact length between the lower protective cavity 16 and the corresponding copper screen 15 along the height direction is not less than 50 mm. This ensures that the upper and lower protective cavities provide sufficient cooling to the copper screen, avoiding insufficient cooling that could cause the copper screen 15 to overheat.

[0033] In some embodiments of the present invention, at least one clamp is placed in the contact area between the copper screen 15 and the upper protective cavity 8 or the lower protective cavity 16 to achieve full contact between the indium sheet 17 and the copper screen 15 and the upper protective cavity 8 or the lower protective cavity 16.

[0034] In some embodiments of the present invention, a high thermal resistance insulating gasket 11 is provided between the test cavity 13 and the copper screen 15, which effectively suppresses the influence of the copper screen on the heat leakage of the test cavity.

[0035] In some embodiments of the present invention, the insulating gasket 11 is a PTFE gasket, and the thickness of the insulating gasket 11 deviates very little from the thickness of the indium sheet 17, not exceeding 2 mm.

[0036] In some embodiments of the present invention, the contact length between the test cavity 13 and the copper screen 15 along the height direction is no more than 10 mm, so as to minimize the influence of the copper screen on the heat leakage of the test cavity.

[0037] In some embodiments of the present invention, the copper screen 15 has a plurality of holes 20 along the horizontal direction. Figure 2 It is recommended to use 4-6 holes to ensure smooth vacuuming inside the copper screen 15, guaranteeing a high vacuum level in the internal area of ​​the copper screen and improving the insulation effect. The aperture of the hole 20 is preferably 6 mm to avoid parasitic heat leakage caused by excessively large apertures.

[0038] In some embodiments of the present invention, the cryogenic liquid injection unit includes a cryogenic liquid storage tank; the test chamber 13 is connected to the cryogenic liquid storage tank through a pipe and a first gate valve 1 provided on the pipe; the lower protection chamber 16 is connected to the cryogenic liquid storage tank through a pipe and a second gate valve 2 provided on the pipe; and the upper protection chamber 13 and the lower protection chamber 16 are connected through a pipe.

[0039] In some embodiments of the present invention, the exhaust unit includes a high-altitude exhaust pipe, an upper protective chamber 13 is connected to the high-altitude exhaust pipe through a pipe, a test chamber 13 is connected to the high-altitude exhaust pipe through a pipe and a third gate valve 3, a pipe between the test chamber 13 and the third gate valve 3 is connected to the air-cooled screen 12 through a fourth gate valve 9, and the air-cooled screen 12 is connected to the high-altitude exhaust pipe through a pipe.

[0040] The third gate valve 3 and the fourth gate valve 9 are responsible for controlling the discharge flow path of the test chamber 13. There are two paths for gas discharge from the test chamber 13: one is direct discharge through the pipe and the third gate valve 3, followed by high-altitude discharge; the other is first introduced into the air-cooled screen 12 through the fourth gate valve 9, and then discharged from the air-cooled screen 12. When the gas discharged from the test chamber 13 is introduced into the air-cooled screen 12, the connecting pipe between the test chamber 13 and the air-cooled screen 12, and the fourth gate valve 9, must be located in the area between the test chamber 13 and the upper protective chamber 8 to avoid an excessively long inlet pipe for the air-cooled screen 12, which could lead to an underestimation of the cooling effect of the air-cooled screen.

[0041] In some embodiments of the present invention, the data acquisition unit includes a mass flow meter 4 and a thermometer group 14. The mass flow meter 4 accurately measures the mass flow rate of the gas discharged from the test chamber 13. The thermometer group 14 is used to measure the temperature of the outer wall of the insulation material 18, the outer wall of the test chamber 13, and the outer wall of the air-cooled screen 12.

[0042] In some embodiments of the present invention, the support member 10 is a steel pipe.

[0043] In some embodiments of the present invention, the sealed container includes a housing 19 and a cover plate 5 connected to the top of the housing, the housing 19 and the cover plate 5 forming a closed cavity through a sealing connection. The molecular pump unit 7 is installed on the side wall of the housing 19; the full-scale gauge 6 is installed on the cover plate 5.

[0044] The present invention provides a method for testing the insulation performance of a large-volume cryogenic storage tank with an air-cooled shield, comprising: The sealed cavity is evacuated to a preset vacuum level; Low-temperature liquid is injected into the upper protective chamber 8, the test chamber 13, and the lower protective chamber 16. The gas volatilized in the protective chamber 8 and the lower protective chamber 16 is discharged through the exhaust unit; the gas volatilized in the test chamber 13 is discharged through the air-cooled screen 12 and then through the exhaust unit. The flow rate of the volatile gas in the test chamber 13 and the temperature of the outer wall of the insulation material 18, the outer wall of the test chamber 13, and the outer wall of the air-cooled screen 12 are measured. After the flow rate of the volatile gas in the test chamber 13 stabilizes, the heat flow of the low-temperature storage tank leakage and the apparent thermal conductivity of the insulation material 18 are calculated based on the measurement results.

[0045] In some embodiments of the present invention, the formula for calculating the heat flow leakage of the cryogenic storage tank is as follows: (1) In the formula, m It is the mass flow rate of the volatile gas in test chamber 13, kg / s; h fg It is the latent heat of vaporization of cryogenic liquids, J / Kg; d i It is the outer diameter of test cavity 13, in meters (m). l It is the height of test cavity 13, in meters (m). The formula for calculating the apparent thermal conductivity of the insulation material 18 on the inner side of the air-cooled screen 12 is as follows: (2) In the formula, d 1 is the outer diameter of the inner insulation material 18 of the air-cooled screen 12, in meters; T 1 is the temperature difference, in K, between the outer wall of the insulation material 18 inside the air-cooled screen 12 and the outer wall of the test chamber 13; The formula for calculating the apparent thermal conductivity of the outer insulation material 18 of the air-cooled screen 12 is as follows: (3) In the formula, d o It is the outer diameter, in meters, of the outer insulation material 18 on the outside of the air-cooled screen 12. d 2 is the outer diameter of the air-cooled screen 12, in meters; T2 is the temperature difference, in K, between the outer wall of the insulation material 18 on the outside of the air-cooled screen 12 and the outer wall of the air-cooled screen 12.

[0046] In a specific embodiment of the present invention, the method for testing the thermal insulation performance of the large-volume cryogenic storage tank containing the gas-cooled shield 12 includes the following steps: Step 1: Cover the side walls of the upper protective cavity 8, the lower protective cavity 16, and the test cavity 13 with the insulation material 18, as well as the top of the upper protective cavity 8 and the bottom of the lower protective cavity 16. Step 2: After installing the upper protective cavity 8, the test cavity 13 and the lower protective cavity 16 into the outer shell 19, the cover plate 5 is connected and sealed to the outer shell 19 through the flange; Step 3: Close the third gate valve 3 and open the fourth gate valve 9; Step 4: Turn on the molecular pump unit 7. When the reading of the full-scale gauge 6 is lower than 0.001 Pa, open the first gate valve 1 and the second gate valve 2 to inject cryogenic liquid into the upper protection chamber 8, the test chamber 13 and the lower protection chamber 16. The gas generated by the vaporization of the cryogenic liquid in the test chamber 13 passes through the air-cooled screen 12 and the mass flow meter 4 in sequence and is discharged from the high-altitude discharge pipe. Step 5: When the reading of mass flow meter 4 is stable, read the readings of mass flow meter 4 and thermometer group 14, and calculate the heat flow of the cryogenic storage tank leakage according to formula (1): (1) In the formula, m It is a mass flow meter reading of 4 kg / s; h fg It is the latent heat of vaporization of cryogenic liquids, J / Kg; d i It is the outer diameter of test cavity 13, in meters (m). l It is the height of test cavity 13, in meters (m). The apparent thermal conductivity of the insulating material 18 inside the air-cooled screen 12 is calculated according to formula (2): (2) In the formula, d 1 is the outer diameter of the inner insulation material 18 of the air-cooled screen 12, in meters; T 1 is the temperature difference, in K, between the outer wall of the insulation material 18 inside the air-cooled screen 12 and the outer wall of the test chamber 13; The apparent thermal conductivity of the outer insulating material 18 of the air-cooled screen 12 is calculated according to formula (3): (3) In the formula, d o It is the outer diameter, in meters, of the outer insulation material 18 on the outside of the air-cooled screen 12. d 2 is the outer diameter of the air-cooled screen 12, in meters; T 2 is the temperature difference, in K, between the outer wall of the insulation material 18 on the outside of the air-cooled screen 12 and the outer wall of the air-cooled screen 12.

[0047] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A testing device for the thermal insulation performance of a large-volume cryogenic storage tank with an air-cooled shield, characterized in that, Includes a sealed container, a vacuum unit, a cryogenic liquid injection unit, an exhaust unit, and a data acquisition unit; The sealed cavity inside the sealed container is provided with an upper protective cavity (8), a test cavity (13) and a lower protective cavity (16) arranged from top to bottom; the bottom of the upper protective cavity (8) and the top of the test cavity (13) and the bottom of the test cavity (13) and the top of the lower protective cavity (16) are connected by a support member (10); the lower outer wall of the upper protective cavity (8) and the upper outer wall of the test cavity (13) and the lower outer wall of the test cavity (13) and the upper outer wall of the lower protective cavity (16) are connected by a copper screen (15); the outer walls of the upper protective cavity (8), the test cavity (13) and the lower protective cavity (16), as well as the top of the upper protective cavity (8), the bottom of the lower protective cavity (16) and the outer wall of the copper screen (15) are all covered with heat insulation material (18), and an air-cooled screen (12) is provided in the heat insulation material of the outer wall of the test cavity (13); The vacuum pumping unit is used to evacuate the sealed cavity. The cryogenic liquid injection unit is used to inject cryogenic liquid into the upper protective cavity (8), the test cavity (13), and the lower protective cavity (16). The exhaust unit is used to exhaust the gas in the upper protective cavity (8), the test cavity (13), the lower protective cavity (16), and the air-cooled screen (12). The data acquisition unit is used to measure the flow rate of the volatile gas in the test cavity (13) and the temperature of the outer wall of the inner heat insulation material (18) of the air-cooled screen (12), the outer wall of the outer heat insulation material (18) of the air-cooled screen (12), the outer wall of the test cavity (13), and the outer wall of the air-cooled screen (12).

2. The device for testing the thermal insulation performance of a large-volume cryogenic storage tank with an air-cooled shield according to claim 1, characterized in that, An indium sheet is provided between the lower outer wall of the upper protective cavity (8) and the corresponding copper screen (15), and an indium sheet is provided between the upper outer wall of the lower protective cavity (16) and the corresponding copper screen (15).

3. The device for testing the thermal insulation performance of a large-volume cryogenic storage tank with an air-cooled shield according to claim 1, characterized in that, The contact length between the upper protective cavity (8) and the corresponding copper screen (15) along the height direction is not less than 50 mm; the contact length between the lower protective cavity (16) and the corresponding copper screen (15) along the height direction is not less than 50 mm.

4. The device for testing the thermal insulation performance of a large-volume cryogenic storage tank with an air-cooled shield according to claim 1, characterized in that, An insulating gasket (11) is provided between the test chamber (13) and the copper screen (15).

5. The device for testing the insulation performance of a large-volume cryogenic storage tank with an air-cooled shield according to claim 1, characterized in that, The contact length between the test cavity (13) and the copper screen (15) along the height direction is no more than 10 mm.

6. The device for testing the insulation performance of a large-volume cryogenic storage tank with an air-cooled shield according to claim 1, characterized in that, The copper screen (15) has multiple holes (20) along the horizontal direction.

7. The device for testing the insulation performance of a large-volume cryogenic storage tank with an air-cooled shield according to claim 1, characterized in that, The cryogenic liquid injection unit includes a cryogenic liquid storage tank; the test chamber (13) is connected to the cryogenic liquid storage tank through a pipe and a first gate valve (1) installed on the pipe; the lower protection chamber (16) is connected to the cryogenic liquid storage tank through a pipe and a second gate valve (2) installed on the pipe; and the upper protection chamber (13) and the lower protection chamber (16) are connected through a pipe.

8. The device for testing the thermal insulation performance of a large-volume cryogenic storage tank with an air-cooled shield according to claim 1, characterized in that, The exhaust unit includes a high-altitude exhaust pipe, an upper protective chamber (13) connected to the high-altitude exhaust pipe via a pipe, a test chamber (13) connected to the high-altitude exhaust pipe via a pipe and a third gate valve (3), a pipe between the test chamber (13) and the third gate valve (3) connected to an air-cooled screen (12) via a fourth gate valve (9), and an air-cooled screen (12) connected to the high-altitude exhaust pipe via a pipe.

9. A method for testing the insulation performance of a large-volume cryogenic storage tank with an air-cooled shield, characterized in that, include: The sealed cavity is evacuated to a preset vacuum level; Low-temperature liquid is injected into the upper protective chamber (8), the test chamber (13), and the lower protective chamber (16). The gas volatilized in the protective chamber (8) and the lower protective chamber (16) is discharged through the exhaust unit. The gas volatilized in the test chamber (13) is discharged through the air-cooled screen (12) and then discharged through the exhaust unit. The flow rate of the volatile gas in the test chamber (13) and the temperature of the outer wall of the insulation material (18), the outer wall of the test chamber (13) and the outer wall of the air-cooled screen (12) are measured. After the flow rate of the volatile gas in the test chamber (13) stabilizes, the heat flow of the low temperature storage tank leakage and the apparent thermal conductivity of the insulation material (18) are calculated based on the measurement results.

10. The method for testing the insulation performance of a large-volume cryogenic storage tank with an air-cooled shield according to claim 9, characterized in that, The formula for calculating the heat flow leakage from a cryogenic storage tank is: （1） In the formula, m It is the mass flow rate of the volatile gas in the test chamber (13), kg / s; h fg It is the latent heat of vaporization of cryogenic liquids, J / Kg; d i It is the outer diameter of the test cavity (13), in meters; l It is the height of the test cavity (13), in meters; The formula for calculating the apparent thermal conductivity of the insulation material (18) inside the air-cooled screen (12) is as follows: （2） In the formula, d 1 is the outer diameter (m) of the insulation material (18) inside the air-cooled screen (12); T 1 is the temperature difference, K, between the outer wall of the inner insulating material (18) of the air-cooled screen (12) and the outer wall of the test chamber (13); The formula for calculating the apparent thermal conductivity of the insulation material (18) on the outside of the air-cooled screen (12) is as follows: （3） In the formula, d o It is the outer diameter (m) of the insulation material (18) on the outside of the air-cooled screen (12); d 2 is the outer diameter of the air-cooled screen (12), in meters; T 2 is the temperature difference between the outer wall of the insulation material (18) on the outside of the air-cooled screen (12) and the outer wall of the air-cooled screen (12), in K.

Images