Supersonic expansion and liquefaction liquid hydrogen preparation system
Through the supersonic expansion liquefaction system, the unliquefied hydrogen is recycled, combined with high-pressure ejectors and multi-stage compressors, the problems of low efficiency and complex equipment in the liquid hydrogen preparation system are solved, and efficient and low-cost liquid hydrogen preparation is achieved.
Patent Information
- Application Number
- CN202422723303.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-09-23
- Estimated Expiration
- 2034-11-08
AI Technical Summary
Existing liquid hydrogen preparation systems have problems such as low efficiency, complex equipment, and high cost, especially in the liquefaction and storage and transportation processes, where energy consumption is high and the equipment is complex.
The liquid hydrogen preparation system adopts supersonic expansion liquefaction. Through the combination of hydrogen storage tanks, the first hydrogen compressor, the heat exchanger and the supersonic separator, the unliquefied hydrogen is recycled and combined with high-pressure ejectors and multi-stage compressors to achieve efficient liquefaction of hydrogen.
It improves heat exchange efficiency, reduces energy consumption and equipment load, extends equipment life, reduces operating costs, and improves the overall efficiency and stability of the system.
Smart Images
Figure CN223376182U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of liquid hydrogen preparation, in particular to a liquid hydrogen preparation system using supersonic expansion and liquefaction. Background Art
[0002] At present, there are mainly the following forms of hydrogen transportation, among which liquid hydrogen occupies an important position.
[0003] Compressed gaseous hydrogen is currently the most common form of hydrogen transportation. Hydrogen is stored in high-pressure gas cylinders or pipelines at a high pressure of 350-700 bar at room temperature. The advantages are mature technology and relatively complete infrastructure, but the energy density of hydrogen is relatively low, resulting in higher storage and transportation costs per unit volume.
[0004] Liquid hydrogen is another important form of hydrogen transportation. After hydrogen is liquefied at -253°C, its volume is greatly reduced and its energy density is significantly increased, giving liquid hydrogen obvious advantages in long-distance and large-scale transportation. The main features of liquid hydrogen transportation include: 1. High energy density: The volume energy density of liquid hydrogen is about 8 times that of gaseous hydrogen. This allows liquid hydrogen to carry more energy under the same transportation volume, making it more suitable for long-distance and large-scale transportation; 2. Typical transportation methods: Liquid hydrogen is usually transported over long distances by means of transportation such as cryogenic insulated tank trucks and liquid hydrogen tank ships. Liquid hydrogen tank trucks have been widely used in commercial transportation, while tank ships are mostly used for intercontinental transportation. However, liquid hydrogen transportation currently faces some challenges, namely, hydrogen volatilization may occur during extremely low-temperature storage and transportation. In addition, the low-temperature preparation process of liquefied hydrogen itself consumes a lot of energy.
[0005] In the transportation of chemical hydrogen carriers, ammonia, as a hydrogen carrier, can release hydrogen by decomposition. Ammonia storage and transportation technology is mature, low-cost, and can be stored and transported in liquid form at room temperature and pressure, so it has attracted much attention in long-distance hydrogen transportation. Ammonia has great potential in areas with incomplete hydrogen energy infrastructure, but its decomposition process to produce hydrogen is relatively complicated. Organic liquid hydrogen carriers, referred to as LOHCs, are a technology that combines hydrogen with organic liquid compounds to produce liquid hydrides that can be stored and transported, and then releases hydrogen through catalytic reactions at the destination. LOHCs do not require low-temperature storage and transportation and can be used in existing liquid fuel transportation networks, but require additional hydrogenation and dehydrogenation equipment, which increases the overall cost and complexity.
[0006] Liquid hydrogen plays an important role in the fields of long-distance hydrogen transportation, aerospace applications, hydrogen fuel vehicles, etc. Especially in the context of the development of the global hydrogen economy, liquid hydrogen has become one of the preferred forms of cross-border and intercontinental hydrogen transportation due to its high energy density and efficient transportation mode. In addition, liquid hydrogen has also become the preferred fuel form in deep space exploration, aerospace and other fields due to its light weight and high energy density. In summary, liquid hydrogen plays an important role in the long-distance and large-scale transportation of hydrogen, especially showing significant advantages in cross-border and maritime transportation, but its high liquefaction and storage and transportation costs remain a challenge.
[0007] At present, the mainstream technical paths for hydrogen liquefaction mainly include the Joule-Thomson effect method, the pre-cooling-expansion liquefaction method, the mixed refrigerant cycle method and the Claude cycle method. Among them, the principle of the Joule-Thomson effect method is to reduce the temperature of hydrogen by adiabatic expansion, and finally liquefy it to produce liquid hydrogen. The advantage is that the equipment is simple and suitable for small-scale refrigeration and low-temperature applications. The disadvantage is that it has low efficiency, requires large compression work, and has high energy consumption. It is mostly used in the pre-cooling stage of liquefied nitrogen or other gases; the second method is the pre-cooling-expansion liquefaction method. The principle of the pre-cooling-expansion liquefaction method is to pre-cool hydrogen with liquid nitrogen or other refrigerants, and then use an expander to cool and liquefy it to produce liquid hydrogen. The advantage is that the efficiency can be improved through multi-stage pre-cooling. It is commonly used in large-scale liquefaction equipment. The disadvantage is that the equipment is complex and the initial investment is high. Large, requiring an additional pre-cooling cold source; the third method is the mixed refrigerant cycle method. The principle of the mixed refrigerant cycle method is to use mixed refrigerants with different boiling points to cool hydrogen in stages, gradually reaching the liquefaction temperature to produce liquid hydrogen. The advantage is high efficiency, and it is particularly suitable for large-scale liquefaction. The disadvantage is that the process is complex, the precise control of the refrigerant composition is high, and the maintenance cost is high; the fourth method is the Claude cycle method. The principle of the Claude cycle method is to use hydrogen expansion and pre-cooling for liquefaction, and is usually used in combination with other liquefaction technologies. The advantage is high efficiency and it is suitable for medium and large hydrogen liquefaction equipment. The disadvantage is that the equipment is complex and the manufacturing and maintenance costs are high.
[0008] In summary, the above four methods either have low efficiency in preparing liquid hydrogen and high energy consumption, or have complex processes and equipment, and high manufacturing and maintenance costs. Therefore, there is an urgent need for an energy-saving and simple liquid hydrogen preparation system. Utility Model Content
[0009] In response to the deficiencies in the above-mentioned background technology, the present invention proposes a liquid hydrogen preparation system using supersonic expansion liquefaction, which solves the technical problems of existing hydrogen liquefaction equipment being simple but inefficient and high-efficiency but complex equipment and processes.
[0010] The technical solution of this application is:
[0011] A liquid hydrogen preparation system using supersonic expansion and liquefaction comprises a hydrogen storage tank, a first hydrogen compressor, a heat exchanger, and a supersonic separator for hydrogen liquefaction and separation, which are connected in sequence. A first outlet of the supersonic separator is connected to the liquid hydrogen storage tank, and a second outlet of the supersonic separator is connected to an inlet of the supersonic separator via a hydrogen circulation pipeline.
[0012] Preferably, the first outlet is provided at the end of the liquid discharge structure of the supersonic separator, and the second outlet is provided at the end of the diffuser of the supersonic separator.
[0013] Preferably, the hydrogen circulation pipeline includes a high-pressure ejector connected to the second outlet, and the high-pressure ejector is connected to the inlet via a third hydrogen compressor and the heat exchanger in sequence.
[0014] Preferably, the hydrogen circulation pipeline includes a high-pressure ejector connected to the second outlet, and the high-pressure ejector is connected to the inlet through the first hydrogen compressor and the heat exchanger in sequence.
[0015] Preferably, the high-pressure ejector includes a fluid chamber and an air intake chamber located at the inlet end, and a mixing chamber outlet located at the outlet end. A mixing chamber is provided between the inlet end and the outlet end. The second outlet is connected to the air intake chamber. The hydrogen storage tank is connected to the fluid chamber through a second hydrogen compressor, and the third hydrogen compressor is connected to the mixing chamber outlet.
[0016] Preferably, the axis of the fluid cavity is parallel to the flow direction of hydrogen along the high-pressure injector, and the axis of the air intake cavity is perpendicular to the axis of the fluid cavity.
[0017] Preferably, the diameter of the inlet end is larger than the diameter of the outlet end, and the diameter of the outlet end is larger than the diameter of the mixing chamber.
[0018] Preferably, the compression ratio of the second hydrogen compressor is greater than the compression ratio of the third hydrogen compressor.
[0019] Preferably, the compression ratio of the first hydrogen compressor is greater than the compression ratio of the third hydrogen compressor.
[0020] Preferably, the refrigerant of the heat exchanger is nitrogen, helium or natural gas.
[0021] Compared with the prior art, the technical solution disclosed in this utility model has the following beneficial effects:
[0022] 1. By recycling unliquefied hydrogen and re-exchanging and liquefying the remaining hydrogen after the first heat exchange, this not only effectively improves heat exchange efficiency but also significantly reduces energy consumption and losses in the primary hydrogen compressor, compared to simply exchanging heat with the hydrogen in the hydrogen storage tank. Hydrogen can be fully utilized during the liquefaction process, reducing energy waste, improving overall system efficiency and stability, extending equipment life, and reducing operating costs, resulting in significant economic and environmental benefits.
[0023] 2. The unliquefied hydrogen is introduced into the high-pressure ejector and mixed with the high-pressure mainstream hydrogen pressurized by the second hydrogen compressor. The hydrogen then flows through the third hydrogen compressor or the first hydrogen compressor at a higher pressure to re-enter the heat exchange and liquefaction process. The liquid hydrogen preparation system is simple, reduces the load on the hydrogen compressor, reduces the energy consumption of hydrogen liquefaction, and improves the liquefaction efficiency of hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0025] Figure 1 It is a working principle diagram of the utility model.
[0026] Description of Figure Numbers:
[0027] 1 Hydrogen storage tank, 2 First hydrogen compressor, 3 Heat exchanger, 4 Supersonic separator, 4-1 First outlet, 4-2 Second outlet, 5 High-pressure ejector, 5-1 Intake chamber, 5-2 Fluid chamber, 5-3 Mixing chamber outlet, 6 Liquid hydrogen storage tank, 7 Second hydrogen compressor, 8 Third hydrogen compressor. DETAILED DESCRIPTION
[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the core concept of the present invention and the following embodiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0029] Example 1, a liquid hydrogen preparation system using supersonic expansion liquefaction, such as Figure 1As shown, it includes a hydrogen storage tank 1, a first hydrogen compressor 2, a heat exchanger 3 and a supersonic separator 4 for hydrogen liquefaction separation, which are connected in sequence. The first outlet 4-1 of the supersonic separator 4 is connected to a liquid hydrogen storage tank 6, and the second outlet 4-2 of the supersonic separator 4 is connected to the inlet of the supersonic separator 4 through a hydrogen circulation pipeline.
[0030] Specifically, along the flow direction of hydrogen, the supersonic separator 4 includes a cyclone, a supersonic nozzle, a cyclone separation working area, and a gas-liquid separator, which are connected in sequence. The hydrogen expands and liquefies as it flows in the tube. The liquefied liquid hydrogen eventually flows through the liquid discharge structure of the gas-liquid separator and enters the liquid hydrogen storage tank 6. The unliquefied hydrogen flows through the diffuser of the gas-liquid separator and enters the hydrogen circulation pipeline, where it is repeatedly pressurized and heat-exchanged, and then expands and liquefies in the supersonic separator 4. In this cycle, the unliquefied hydrogen is recycled, which not only effectively improves the heat exchange efficiency but also significantly reduces the energy consumption and loss for hydrogen compression. The hydrogen can be fully utilized during the liquefaction process, which not only reduces energy waste, but also improves the overall efficiency and stability of the system, extends the service life of the system, reduces operating costs, and has significant economic and environmental benefits.
[0031] Example 2, based on Example 1, provides a liquid hydrogen preparation system using supersonic expansion and liquefaction, wherein the first outlet 4-1 is located at the end of the liquid discharge structure of the supersonic separator 4, and the second outlet 4-2 is located at the end of the diffuser of the supersonic separator 4. The first outlet 4-1 is located at the end of the liquid discharge structure, which can completely collect the liquefied liquid hydrogen and enter the liquid hydrogen storage tank 6. The diffuser of the supersonic separator 4 is also provided with guide vanes. The second outlet 4-2 is located at the end of the diffuser. Before the hydrogen flows out, the guide vanes in the diffuser can be used to guide the hydrogen, reducing the flow resistance of the hydrogen and allowing the hydrogen to completely and quickly enter the hydrogen circulation pipeline.
[0032] Example 3, based on Example 2, provides a liquid hydrogen production system using supersonic expansion and liquefaction, wherein the hydrogen circulation pipeline includes a high-pressure ejector 5 connected to the second outlet 4-2, which is connected to the inlet via a third hydrogen compressor 8 and the heat exchanger 3. Unliquefied hydrogen flows out of the second outlet 4-2, flows through the high-pressure ejector 5, and is then re-pressurized by the third hydrogen compressor 8. It is then reheated by the heat exchanger 3 and expanded and liquefied by the supersonic separator 4, thereby achieving hydrogen recycling.
[0033] Example 4, based on Example 2, a supersonic expansion and liquefaction liquid hydrogen preparation system, the hydrogen circulation pipeline includes a high-pressure ejector 5 connected to the second outlet 4-2, and the high-pressure ejector 5 is connected to the inlet through the first hydrogen compressor 2 and the heat exchanger 3 in sequence. After the unliquefied hydrogen flows out through the second outlet 4-2, it flows through the high-pressure ejector 5 and is pressurized again by the first hydrogen compressor 2. The unliquefied hydrogen is mixed with the hydrogen directly flowing out of the hydrogen storage tank 1, and then heat is exchanged again by the heat exchanger 3 and expanded and liquefied by the supersonic separator 4, thereby realizing the recycling of hydrogen. Mixing the unliquefied hydrogen with the hydrogen directly flowing out of the hydrogen storage tank 1 helps to reduce the load of the first hydrogen compressor 2 and reduce the energy consumption of hydrogen liquefaction.
[0034] Example 5. Based on Example 3, a liquid hydrogen preparation system with supersonic expansion liquefaction is provided, wherein the high-pressure ejector 5 includes a fluid chamber and an air intake chamber located at the inlet end, and a mixing chamber outlet located at the outlet end. A mixing chamber is provided between the inlet end and the outlet end. The second outlet of the supersonic separator 4 is connected to the air intake chamber. The hydrogen storage tank 1 is connected to the fluid chamber through the second hydrogen compressor 7, and the third hydrogen compressor 8 is connected to the mixing chamber outlet 5-3.
[0035] In this embodiment, the fluid chamber and the suction chamber allow hydrogen to flow in, and the mixing chamber balances the pressure of the incoming hydrogen. Finally, the pressure-balanced hydrogen is smoothly discharged at the mixing chamber outlet, with the hydrogen pressure at the mixing chamber outlet being between the pressure of the hydrogen flowing into the fluid chamber and the pressure of the hydrogen flowing into the suction chamber. The hydrogen flowing out of the second outlet of the supersonic separator 4 is at a lower pressure, exhibiting a disordered flow. The hydrogen then flows out of the mixing chamber of the high-pressure ejector 5, mixing and achieving smoother hydrogen flow and more balanced hydrogen pressure.
[0036] Specifically, the hydrogen in the hydrogen storage tank 1 is first compressed by the second hydrogen compressor 7 to become high-pressure hydrogen. The high-pressure hydrogen enters the fluid cavity from the first inlet 5-1, and the low-pressure hydrogen remaining after liquefaction and separation by the supersonic separator 4 enters the intake cavity from the second inlet 5-2. Since the high-pressure hydrogen in the fluid cavity has a high flow rate and a high pressure, a negative pressure is formed when the high-pressure hydrogen flows into the mixing cavity. The hydrogen in the intake cavity has a low flow rate and a low pressure. Under the action of the negative pressure and the high-pressure hydrogen flow rate, the low-pressure hydrogen is brought into the mixing cavity and is fully mixed with the high-pressure hydrogen during the process of being brought in. The mixed hydrogen then flows out of the mixing cavity outlet 5-3 of the high-pressure ejector 5 at a relatively high pressure state so as to be re-pressurized and enter the heat exchange and liquefaction process.
[0037] Example 6, based on Example 5, provides a liquid hydrogen preparation system using supersonic expansion and liquefaction, wherein the axis of the fluid chamber is parallel to the flow direction of the hydrogen along the high-pressure injector 5, and the axis of the intake chamber is perpendicular to the axis of the fluid chamber. Furthermore, the high-pressure injector 5 is generally shaped like a hollow tube, wherein the hydrogen flowing from the fluid chamber flows along the axis of the hollow tube into the mixing chamber, and the hydrogen flowing from the intake chamber flows into the mixing chamber in a direction perpendicular to the axis of the hollow tube. During the process of high-pressure hydrogen flowing into the mixing chamber, a negative pressure is formed at the connection between the fluid chamber and the intake chamber. Driven by the negative pressure and the flow rate of hydrogen entering from the fluid chamber, the hydrogen flowing from the intake chamber enters the mixing chamber, and the hydrogen entering from the two directions mixes from the time they meet until they enter the mixing chamber.
[0038] Example 7, based on Example 6, a liquid hydrogen production system using supersonic expansion liquefaction, wherein the diameter of the inlet end is greater than the diameter of the outlet end, and the diameter of the outlet end is greater than the diameter of the mixing chamber. Furthermore, the diameter of the high-pressure injector 5 along the direction of hydrogen flow is gradually contracted and expanded, with the inlet end having the largest diameter, which can reduce the flow resistance of hydrogen and facilitate the inflow of a large amount of hydrogen. The mixing chamber has the smallest diameter, which facilitates reducing the hydrogen flow rate, increasing the hydrogen mixing time, and making the hydrogen pressure more balanced. The outlet end has an intermediate diameter, which allows the pressure-balanced hydrogen to flow out at a moderate flow rate, improving the efficiency of liquid hydrogen production, and avoiding the hydrogen staying in the high-pressure injector 5 for too long and the excessive amount of hydrogen staying in the high-pressure injector 5, resulting in excessive hydrogen pressure in the mixing chamber.
[0039] Example 8, based on Example 7, provides a liquid hydrogen production system using supersonic expansion and liquefaction, wherein the compression ratio of the second hydrogen compressor 7 is greater than the compression ratio of the third hydrogen compressor 8. The second hydrogen compressor 7 is used to compress and pressurize the hydrogen in the hydrogen storage tank 1, and drives the low-pressure hydrogen remaining after liquefaction and separation by the supersonic separator 4 into the mixing chamber of the high-pressure ejector 5. After the high-pressure hydrogen and low-pressure hydrogen are mixed, they are at a higher pressure. The third hydrogen compressor 8 is used to compress and pressurize the mixed hydrogen. The energy consumption required for re-pressurization is relatively low. The low compression ratio of the third hydrogen compressor 8 can reduce the energy consumption of the liquid hydrogen production system and reduce operating costs. The high compression ratio of the second hydrogen compressor 7 can enhance the hydrogen circulation effect, improve the heat exchange efficiency, and thus improve the overall efficiency of the liquid hydrogen production system.
[0040] Example 9, based on Example 8, provides a liquid hydrogen production system using supersonic expansion and liquefaction, wherein the compression ratio of the first hydrogen compressor 2 is greater than that of the third hydrogen compressor 8. The third hydrogen compressor 8 is used to compress and pressurize the mixed hydrogen flowing out of the high-pressure ejector 5 at a relatively high pressure. Compared to directly compressing and pressurizing the hydrogen in the hydrogen storage tank 1, the energy consumption required for re-pressurization is lower, and therefore the power of the third hydrogen compressor 8 is minimized. In addition, the third hydrogen compressor 8 is used to compress and pressurize the circulating hydrogen, which improves the recycling efficiency of the hydrogen and also reduces the operating load of the first hydrogen compressor 2 to a certain extent.
[0041] Example 10, based on Example 9, provides a liquid hydrogen production system using supersonic expansion liquefaction, wherein the refrigerant in heat exchanger 3 is nitrogen, helium, or natural gas. The refrigerant in heat exchanger 3 flows in the opposite direction to the hydrogen flow. The refrigerant is used to cool the high-pressure hydrogen to bring it close to or reach its critical temperature, thereby improving the liquefaction efficiency of the hydrogen in supersonic separator 4.
[0042] When Example 10 is implemented, the hydrogen in the hydrogen storage tank 1 is first compressed and pressurized by the first hydrogen compressor 2, then cooled by the heat exchanger 3, and then sent to the supersonic separator 4 for liquefaction and separation. The liquid hydrogen liquefied by the supersonic separator 4 is directly sent to the liquid hydrogen storage tank 6 for storage, and the remaining hydrogen not liquefied by the supersonic separator 4 enters the intake chamber of the high-pressure injector 5; at the same time, the hydrogen in the hydrogen storage tank 1 is compressed and pressurized into high-pressure hydrogen by the second hydrogen compressor 7, and the high-pressure hydrogen enters the fluid chamber of the high-pressure injector 5. When the high-pressure hydrogen enters the mixing chamber from the fluid chamber, the remaining hydrogen not liquefied by the supersonic separator 4 is sucked in and fully mixed in the mixing chamber to obtain mixed hydrogen. After the mixed hydrogen is compressed and pressurized by the third hydrogen compressor 8 in a relatively high-pressure state, it re-enters the heat exchange and liquefaction process to realize the cyclic liquefaction of hydrogen.
[0043] Anything not described in detail in the present invention is a conventional technical means known to those skilled in the art.
[0044] The above content shows and describes the basic principles, main features and beneficial effects of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.
Claims
1. A liquid hydrogen production system using supersonic expansion liquefaction, characterized by: The invention comprises a hydrogen storage tank (1), a first hydrogen compressor (2), a heat exchanger (3), and a supersonic separator (4) for hydrogen liquefaction separation, which are connected in sequence. A first outlet (4-1) of the supersonic separator (4) is connected to a liquid hydrogen storage tank (6), and a second outlet (4-2) of the supersonic separator (4) is connected to an inlet of the supersonic separator (4) through a hydrogen circulation pipeline.
2. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 1, characterized in that: The first outlet (4-1) is provided at the end of the liquid discharge structure of the supersonic separator (4), and the second outlet (4-2) is provided at the end of the diffuser of the supersonic separator (4).
3. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 2, characterized in that: The hydrogen circulation pipeline comprises a high-pressure ejector (5) connected to the second outlet (4-2), and the high-pressure ejector (5) is connected to the inlet via a third hydrogen compressor (8) and the heat exchanger (3) in sequence.
4. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 2, characterized in that: The hydrogen circulation pipeline comprises a high-pressure ejector (5) connected to the second outlet (4-2), and the high-pressure ejector (5) is connected to the inlet via the first hydrogen compressor (2) and the heat exchanger (3) in sequence.
5. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 3, characterized in that: The high-pressure ejector (5) comprises a fluid chamber and an air intake chamber at an inlet end, and a mixing chamber outlet at an outlet end, a mixing chamber being provided between the inlet end and the outlet end, the second outlet (4-2) being connected to the air intake chamber, the hydrogen storage tank (1) being connected to the fluid chamber via a second hydrogen compressor (7), and the third hydrogen compressor (8) being connected to the mixing chamber outlet (5-3).
6. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 5, characterized in that: The axis of the fluid cavity is parallel to the flow direction of hydrogen along the high-pressure injector (5), and the axis of the air intake cavity is perpendicular to the axis of the fluid cavity.
7. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 6, characterized in that: The diameter of the inlet end is larger than the diameter of the outlet end, and the diameter of the outlet end is larger than the diameter of the mixing chamber.
8. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 7, characterized in that: The compression ratio of the second hydrogen compressor (7) is greater than the compression ratio of the third hydrogen compressor (8).
9. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 8, characterized in that: The compression ratio of the first hydrogen compressor (2) is greater than the compression ratio of the third hydrogen compressor (8).
10. The liquid hydrogen production system using supersonic expansion liquefaction according to claim 9, characterized in that: The refrigerant of the heat exchanger (3) is nitrogen, helium or natural gas.