A superconducting liquid hydrogen energy storage device

Abstract

This invention discloses a superconducting liquid hydrogen energy storage device, belonging to the field of superconducting magnet cooling. It includes: a nitrogen-fixed Dewar containing nitrogen, a liquid hydrogen Dewar containing liquid hydrogen, and a refrigerator. The nitrogen-fixed Dewar is immersed in the liquid hydrogen. The nitrogen encapsulates the superconducting energy storage magnet, providing electrical isolation between the liquid hydrogen and the superconducting energy storage magnet, and providing deformation restraint for the superconducting energy storage magnet. The liquid hydrogen Dewar has a hydrogen liquefaction inlet. The refrigerator is connected to the hydrogen liquefaction inlet and is used to cool the liquid hydrogen, allowing the liquid hydrogen to cool the superconducting energy storage magnet through the nitrogen. This invention comprehensively utilizes the isolation function of nitrogen fixation and the energy storage and cooling functions of liquid hydrogen, simultaneously achieving a high-safety combination of superconducting energy storage and liquid hydrogen energy storage, and nitrogen fixation prevents deformation of the superconducting energy storage magnet.

Description

Technical Field

[0001] This invention belongs to the field of superconducting magnet cooling, and more specifically, relates to a superconducting liquid hydrogen energy storage device. Background Technology

[0002] Currently, the cooling methods for superconducting magnet energy storage are roughly divided into three types: immersion cooling, gas cooling, and conduction cooling. For immersion cooling, the refrigerants used are liquid helium (1.8K-4.2K), liquid nitrogen (63K-77K), liquid neon (24K-27K), and liquid hydrogen (13K-20K).

[0003] Compared to other refrigerants, liquid hydrogen, due to its more reactive chemical properties, is prone to violent chemical reactions, potentially leading to production accidents. When superconducting magnets are immersed in liquid hydrogen, air trapped in their metal gaps may leak out and react with the liquid hydrogen, causing an explosion. Therefore, the superconducting energy storage field currently maintains a cautious approach to liquid hydrogen refrigeration. Meanwhile, as a crucial part of developing renewable energy, the conversion of renewable energy into hydrogen or liquid hydrogen for energy storage and transportation has been a key research focus. Currently, the safety issues surrounding the transportation of hydrogen and liquid hydrogen remain unresolved, and the utilization of hydrogen energy urgently needs development and expansion. Summary of the Invention

[0004] In response to the shortcomings of existing technologies and the need for improvement, this invention provides a superconducting liquid hydrogen energy storage device. Its purpose is to overcome the disadvantage of the hidden accident risks in superconducting energy storage using liquid hydrogen refrigeration, while increasing the utilization scenarios of hydrogen energy and improving the demand for renewable energy.

[0005] To achieve the above objectives, the present invention provides a superconducting liquid hydrogen energy storage device, comprising: a nitrogen-fixing Dewar loaded with nitrogen, a liquid hydrogen Dewar loaded with liquid hydrogen, and a refrigerator, wherein the nitrogen-fixing Dewar is immersed in the liquid hydrogen; the nitrogen-fixed material encapsulates a superconducting energy storage magnet, serving to provide electrical isolation between the liquid hydrogen and the superconducting energy storage magnet, and to provide deformation constraint force for the superconducting energy storage magnet; the liquid hydrogen Dewar is provided with a hydrogen liquefaction inlet; the refrigerator is connected to the hydrogen liquefaction inlet for cooling the liquid hydrogen, so that the liquid hydrogen cools the superconducting energy storage magnet through the nitrogen-fixed material.

[0006] Furthermore, the refrigeration power of the refrigerator satisfies:

[0007]

[0008] Where Q is the cooling power of the refrigerator, σ is the Boltzmann coefficient, A is the surface area of ​​the nitrogen-fixing Dewar, ε is the emissivity of the nitrogen-fixing Dewar, T1 is the temperature outside the nitrogen-fixing device, and T2 is the temperature inside the nitrogen-fixing device.

[0009] Furthermore, the depth of nitrogen fixation immersed in the liquid hydrogen is not less than a depth threshold d0, which is determined by the nitrogen fixation volume, the nitrogen fixation radius, and the operating current of the superconducting energy storage magnet.

[0010] Furthermore, the ratio of the nitrogen-fixed radius to the liquid hydrogen Dewar radius is less than a ratio threshold r0, which is determined by the operating current of the superconducting energy storage magnet and the depth of the nitrogen-fixed part immersed in the liquid hydrogen.

[0011] Furthermore, it also includes a boom and current leads; the boom is used to secure the nitrogen-fixed Dewar and the superconducting energy storage magnet; the current leads are used to connect the superconducting energy storage magnet to the power grid.

[0012] Furthermore, the nitrogen-fixing Dewar is initially filled with liquid nitrogen, and the low temperature conducted by the liquid hydrogen causes the nitrogen element in the liquid nitrogen to solidify from a liquid state to a solid state, and during the solidification process, it adheres to and encapsulates the superconducting energy storage magnet.

[0013] Furthermore, it also includes a barometer for measuring the pressure in the liquid hydrogen dewar, and the refrigerator adjusts its cooling power based on the measurement results from the barometer.

[0014] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0015] (1) Adding nitrogen fixation between the superconducting energy storage magnet and liquid hydrogen as an electrical isolation means that the superconducting energy storage magnet is in direct contact with the inactive nitrogen. In this way, the air in the metal gap of the superconducting energy storage magnet will not come into contact with the liquid hydrogen, and the liquid hydrogen can act as a refrigerant for the superconducting magnet. At the same time, the air and liquid hydrogen are isolated to prevent chemical reactions, improve the production safety level, and reduce the risk of fire.

[0016] (2) Liquid hydrogen (13K-20K) can maintain the nitrogen (63K) state and indirectly provide a cold source for the superconducting energy storage magnet. The nitrogen encapsulates the superconducting energy storage magnet and, in its solid state, constrains the thermal expansion and stress changes generated by the superconducting energy storage magnet during operation, thus preventing the superconducting energy storage magnet from losing its superconductivity due to thermal stress.

[0017] (3) Combining liquid hydrogen energy storage and superconducting magnet energy storage gives full play to the advantages of both, while overcoming the hidden dangers and disadvantages of liquid hydrogen as an energy storage method and refrigerant, expanding the application field of hydrogen energy, and further providing implementation plans and more possibilities for renewable energy development. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the superconducting liquid hydrogen energy storage device provided in an embodiment of the present invention;

[0019] Figure 2A schematic diagram of the liquid hydrogen refrigeration principle of the superconducting liquid hydrogen energy storage device provided in an embodiment of the present invention.

[0020] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0021] 1 is a liquid hydrogen Dewar, 2 is a nitrogen-fixed Dewar, 3 is a hydrogen liquefaction inlet, 4 is a barometer, 5 is a superconducting energy storage magnet, 6 is a current lead, and 7 is a boom. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] In this invention, the terms "first," "second," etc. (if present) in the invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0024] Figure 1 This is a schematic diagram of the structure of a superconducting liquid hydrogen energy storage device provided in an embodiment of the present invention. (See also...) Figure 1 , combined Figure 2 The superconducting liquid hydrogen energy storage device in this embodiment will be described in detail.

[0025] See Figure 1 The superconducting liquid hydrogen energy storage device includes: a nitrogen-fixed Dewar 2 filled with nitrogen, a liquid hydrogen Dewar 1 filled with liquid hydrogen, and a refrigerator (not shown in the figure). The nitrogen-fixed Dewar 2 is immersed in liquid hydrogen. Nitrogen is used to coat the superconducting energy storage magnet 5, providing electrical isolation between the liquid hydrogen and the superconducting energy storage magnet 5, and providing deformation restraint for the superconducting energy storage magnet 5. The liquid hydrogen Dewar 1 is provided with a hydrogen liquefaction inlet 3. The refrigerator is connected to the hydrogen liquefaction inlet 3 to cool the liquid hydrogen, allowing the liquid hydrogen to cool the superconducting energy storage magnet 5 through the nitrogen fixation.

[0026] In superconducting liquid hydrogen energy storage devices, nitrogen fixation, as an inert solid state, isolates the reactive hydrogen element from the residual air in the superconducting energy storage magnet, thus preventing chemical reactions that could lead to safety accidents. Simultaneously, the thermal conduction between nitrogen fixation and the liquid hydrogen and superconducting energy storage magnet makes it possible to use liquid hydrogen for cooling the magnet, significantly improving safety and reliability. Throughout the device, liquid hydrogen acts as an indirect cold source because its low temperature maintains the nitrogen fixation state. Nitrogen fixation provides a cryogenic operating environment for the superconducting coils, and the heat generated by the coils is transferred to the liquid hydrogen via nitrogen fixation, ultimately being carried away by the liquefaction device.

[0027] The liquid hydrogen refrigeration principle of superconducting liquid hydrogen energy storage devices is as follows: Figure 2 As shown, see reference Figure 2 Since the superconducting energy storage magnet is in direct contact with fixed nitrogen, the heat generated when the superconducting energy storage magnet is working is mainly transferred to the liquid hydrogen through nitrogen radiation. Therefore, the cooling power of the refrigerator connected to the liquid hydrogen is greater than the nitrogen radiation heat transfer power.

[0028] Nitrogen fixation radiation heat transfer power Q rad It can be represented as:

[0029] Q rad =σεAT 4

[0030] Where σ is the Boltzmann coefficient, ε is the emissivity of the nitrogen-fixed Dewar, A is the surface area of ​​the nitrogen-fixed Dewar, and T is the temperature of the nitrogen-fixed surface.

[0031] Therefore, the radiation power Q generated on both sides of nitrogen fixation at different temperatures inside and outside can be obtained. rad 'for:

[0032]

[0033] Where E is a coefficient between 0 and 1, and depends on the reflection type of the inner and outer surfaces; T1 is the temperature of the outer surface of the nitrogen-fixed container; T2 is the temperature of the inner surface. The nitrogen-fixed Dewar involved in this embodiment is a coaxial container, and the inner and outer cavity walls exhibit diffuse reflection; therefore:

[0034]

[0035] Where ε1 is the emissivity of the irradiated object, ε2 is the emissivity of the radiating object, A1 is the surface area of ​​the irradiated object, and A2 is the surface area of ​​the radiating object. The heat of nitrogen fixation radiation can be expressed as:

[0036]

[0037] In the embodiments of the present invention, the heat transfer from nitrogen fixation to liquid hydrogen is as follows:

[0038]

[0039] The refrigeration power of the chiller needs to meet the condition Q' greater than 0, that is:

[0040]

[0041] Where Q is the cooling power of the refrigerator, σ is the Boltzmann coefficient, A is the surface area of ​​the nitrogen-fixed Dewar, ε is the emissivity of the nitrogen-fixed Dewar, T1 is the temperature of the outer side of the nitrogen-fixed Dewar, and T2 is the temperature of the inner side of the nitrogen-fixed Dewar. When the heat generated by the superconducting magnet increases, T2 will rise, which will lead to an increase in Q', and the corresponding cooling power will also change accordingly.

[0042] To ensure the superconducting energy storage magnet operates in a cryogenic environment, the depth d of nitrogen fixation immersed in liquid hydrogen must be no less than a depth threshold d0. This depth threshold d0 is determined by the nitrogen fixation volume, nitrogen fixation radius, and the operating current of the superconducting energy storage magnet. A larger d value is more conducive to the stable operation of the superconducting energy storage magnet.

[0043] To ensure the superconducting energy storage magnet operates in a cryogenic environment, the ratio r / R of the nitrogen-fixed radius r to the liquid hydrogen Dewar radius R must be less than the ratio threshold r0. The ratio threshold r0 is determined by the operating current of the superconducting energy storage magnet and the depth of nitrogen immersion in liquid hydrogen. A larger r / R ratio is more beneficial for maintaining the nitrogen-fixed structure and for the superconducting energy storage magnet to function properly. The parameters d, r, and R can be calculated based on the requirements for stable operation of the superconducting energy storage magnet and for maintaining its structure using liquid hydrogen and nitrogen in specific application scenarios.

[0044] According to an embodiment of the present invention, the superconducting liquid hydrogen energy storage device further includes a boom 7 and a current lead 6. The boom 7 is used to fix the nitrogen-fixing Dewar 2 and the superconducting energy storage magnet 5. The current lead 6 is used to connect the superconducting energy storage magnet 5 to the power grid.

[0045] According to an embodiment of the present invention, the nitrogen-fixing Dewar 2 is initially filled with liquid nitrogen. The low temperature of liquid hydrogen conduction causes the nitrogen element in the liquid nitrogen to solidify from a liquid state to a solid state, and during the solidification process, it adheres to and wraps the superconducting energy storage magnet 5.

[0046] According to an embodiment of the present invention, the superconducting liquid hydrogen energy storage device further includes a barometer 4. The barometer 4 is used to measure the pressure change in the liquid hydrogen dewar 1 caused by evaporation, and the refrigerator adjusts its cooling power according to the measurement results of the barometer to ensure safety.

[0047] Because superconducting magnets generate AC losses during operation, these losses affect their temperature. Furthermore, localized heat can cause the magnet to expand, leading to stress and even significant strain. In this embodiment of the invention, a superconducting liquid hydrogen energy storage device has nitrogen fixed between the superconducting energy storage magnet and the liquid hydrogen, tightly encasing the magnet. This limits the thermal stress generated during the magnet's operation, making it less prone to significant strain and reducing the risk of quenching. The nitrogen also serves to isolate the liquid hydrogen from the magnet and transfer heat. The liquid hydrogen, produced by electrolyzing water using electricity generated from renewable energy sources, is liquefied and stored in a Dewar flare, thus serving a dual purpose of energy storage and cooling.

[0048] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A superconducting liquid hydrogen energy storage device, characterized in that, include: The nitrogen-fixing Dewar is loaded with nitrogen fixation, the liquid hydrogen Dewar is loaded with liquid hydrogen, and a refrigerator is used; the nitrogen-fixing Dewar is immersed in the liquid hydrogen. The nitrogen-coated superconducting energy storage magnet is used to provide electrical isolation between the liquid hydrogen and the superconducting energy storage magnet, and to provide deformation constraint force for the superconducting energy storage magnet; The liquid hydrogen Dewar is provided with a hydrogen liquefaction inlet; the refrigerator is connected to the hydrogen liquefaction inlet and is used to cool the liquid hydrogen, so that the liquid hydrogen cools the superconducting energy storage magnet through the nitrogen fixation. The nitrogen-fixing Dewar is initially filled with liquid nitrogen. The low temperature conducted by the liquid hydrogen causes the nitrogen element in the liquid nitrogen to solidify from a liquid state to a solid state, and during the solidification process, it adheres to and wraps the superconducting energy storage magnet. Liquid hydrogen at 13K-20K can maintain a nitrogen-fixed state, indirectly providing a cold source for the superconducting energy storage magnet. The nitrogen-fixed state encapsulates the superconducting energy storage magnet and, in its solid state, constrains the thermal expansion and stress changes generated during operation, thus preventing the superconducting energy storage magnet from losing its superconductivity due to thermal stress.

2. The superconducting liquid hydrogen energy storage device as described in claim 1, characterized in that, The refrigeration power of the refrigerator meets the following requirements: in, The cooling power of the refrigerator is... Boltzmann coefficient, The surface area of ​​the nitrogen-fixing Dewar. The emissivity of the nitrogen-fixing Dewar. The temperature outside the nitrogen fixation zone. This refers to the temperature inside the nitrogen-fixing zone.

3. The superconducting liquid hydrogen energy storage device as described in claim 1, characterized in that, The depth of nitrogen fixation immersed in the liquid hydrogen is not less than a depth threshold. The depth threshold It is determined by the nitrogen fixation volume, nitrogen fixation radius, and the operating current of the superconducting energy storage magnet.

4. The superconducting liquid hydrogen energy storage device as described in claim 3, characterized in that, The ratio of the nitrogen-fixed radius to the liquid hydrogen Dewar radius is less than the ratio threshold. The ratio threshold The depth of nitrogen fixation is determined by the operating current of the superconducting energy storage magnet and the depth of immersion in the liquid hydrogen.

5. The superconducting liquid hydrogen energy storage device as described in claim 1, characterized in that, It also includes the boom and current leads; The boom is used to fix the nitrogen-fixing Dewar and the superconducting energy storage magnet; the current lead is used to connect the superconducting energy storage magnet to the power grid.

6. The superconducting liquid hydrogen energy storage device as described in claim 1, characterized in that, It also includes a barometer for measuring the pressure in the liquid hydrogen dewar, and the refrigerator adjusts its cooling power according to the measurement results of the barometer.

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