Liquid hydrogen low-evaporation efficient storage device based on thermal transpiration effect

Abstract

The invention discloses a liquid hydrogen low-evaporation high-efficiency storage device based on a thermal transpiration effect, comprising: a storage tank, which is sequentially provided with a liquid hydrogen cavity, an inner container, a refrigeration cavity and a shell from inside to outside; the evaporated gas distribution pipe is communicated with the liquid hydrogen cavity; a high-pressure steam collecting pipe; the thermal transpiration type compressor unit is connected between the evaporation gas distribution pipe and the high-pressure steam collecting pipe; a pressure buffer tank; the expansion machine is communicated with the high-pressure steam collecting pipe through a pressure buffer tank; the cold end steam cooling screen is located between the inner container and the thermal transpiration type compressor unit and communicates with the expansion machine; the steam cooling screen is located between the thermal transpiration type compressor unit and the shell and communicates with the cold end pipeline; the hot end steam cooling screen is arranged between the thermal transpiration type compressor unit and the steam cooling screen and communicates with the steam pipeline; and a hot end steam outlet of the hot end pipeline is communicated with the outside. By the adoption of the storage device, heat permeating into the liquid hydrogen cavity from the external environment can be effectively reduced, and low-evaporation and high-efficiency storage of liquid hydrogen is ensured.

Description

Technical Field

[0001] This invention relates to the field of liquid hydrogen storage technology, and in particular to a liquid hydrogen low-evaporation and high-efficiency storage device based on the thermal runoff effect. Background Technology

[0002] Hydrogen energy, as a clean secondary energy source, is of great significance for energy transition and addressing climate change, and has received widespread attention in recent years. With the continuous increase in hydrogen supply and demand, how to achieve safe and efficient hydrogen storage is a pressing issue that needs to be addressed for the large-scale application of hydrogen energy.

[0003] Hydrogen storage is a crucial aspect of hydrogen energy applications. Hydrogen molecules are very small, making them prone to permeation and leakage, which can induce hydrogen embrittlement in materials. Furthermore, hydrogen has an extremely wide flammability range in air (4%-75%) and a very low ignition energy (0.02 mJ), making it highly flammable and explosive. Safe, economical, and sustainable hydrogen storage faces a series of technical challenges. Currently, common hydrogen storage methods include cryogenic liquid storage and high-pressure gaseous storage. Cryogenic liquid storage is a highly efficient method, with a liquid hydrogen density reaching 70.8 kg / m³ at one atmosphere, 788 times that of gaseous hydrogen under standard conditions (0.0899 kg / m³). In terms of unit hydrogen storage capacity, cryogenic liquid storage has a significant advantage over high-pressure gaseous storage. However, if liquid hydrogen storage tanks are exposed to ambient temperature, heat exchange will occur with the surrounding environment. Because the temperature of liquid hydrogen is much lower than ambient temperature, heat from the surrounding environment will be transferred to the liquid hydrogen inside the tank through the container walls. Liquid hydrogen (equilibrium hydrogen) at one atmosphere has a boiling point of 20.38 K and a relatively low latent heat of vaporization. Even a small amount of heat can cause it to evaporate, resulting in a rapid increase in pressure within the storage tank. To ensure safety, a certain amount of this evaporated hydrogen must be released from the tank. Although the evaporated hydrogen can be used directly, such as in hydrogen fuel cell power generation or combustion, these uses are often reactive and unavoidable, and may not meet the specific time and space demands for energy, ultimately leading to a loss of liquid hydrogen. In practical applications, liquid hydrogen storage tanks must be insulated to prevent excessive and rapid entry of external heat into the tank, thereby reducing liquid hydrogen evaporation losses.

[0004] Currently, liquid hydrogen low-evaporation storage technologies mainly include active thermal protection and passive thermal protection technologies, but both technologies have certain drawbacks. Active thermal protection technology involves configuring a cryogenic refrigerator on the cryogenic liquid storage device. This refrigerator generates cooling to offset the heat seeping into the storage device, achieving zero-evaporation storage of liquid hydrogen. Three commonly used cryogenic refrigerators are the Gifford-McMahon Cryogenic Refrigerator, the Pulse Tube Cryogenic Refrigerator, and the Reverse Brayton Cycle Cryogenic Refrigerator; however, their operation requires a significant amount of high-grade electrical or mechanical energy. Passive thermal protection technology employs advanced insulation measures, such as multi-layer insulation and vacuum insulation, to reduce heat conduction and radiation, thereby minimizing heat seepage into the storage device. It does not rely on actively inputting cooling to offset heat seeping from the external environment and has a simpler structure; however, insulation materials, especially high-performance insulation materials, are expensive, and the insulation layer may increase the size and weight of the device. Vapor-Cooled Shield (VCS) technology is also a passive thermal protection technology. It uses low-temperature hydrogen vapor to absorb heat that seeps into the storage device from the external environment, and finally discharges this heat with the hydrogen vapor, thereby further improving the insulation effect. At the same time, discharging the hydrogen vapor also prevents the pressure inside the storage device from rising continuously, ensuring the safe storage of liquid hydrogen. However, this technology still inevitably causes hydrogen loss and fails to fully utilize the cooling capacity of the hydrogen vapor.

[0005] It is evident that developing a method that utilizes the heat from the external environment penetrating into the liquid hydrogen storage device to perform work (essentially utilizing the temperature difference between the external environment and liquid hydrogen) and further achieves cryogenic refrigeration could potentially integrate the advantages of both active and passive thermal protection technologies while mitigating their respective disadvantages. This would help improve the utilization rate of hydrogen vapor cooling capacity without consuming additional high-grade energy, reduce and delay the entry of external heat into the storage device, significantly reduce the liquid hydrogen evaporation rate, and achieve superior low-evaporation and high-efficiency liquid hydrogen storage performance. Summary of the Invention

[0006] The purpose of this invention is to provide a liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect, thereby overcoming the shortcomings of existing liquid hydrogen low-evaporation storage technologies, which either require a large amount of high-grade electrical energy or mechanical energy for active cooling or have low utilization of liquid hydrogen vapor gas cooling energy.

[0007] To achieve the above objectives, the present invention provides a low-evaporation, high-efficiency liquid hydrogen storage device based on the heat flow effect, comprising: a storage tank, which, from the inside out, is provided with a liquid hydrogen chamber, an inner liner, a cooling chamber, and an outer shell, wherein the cooling chamber surrounds the outside of the liquid hydrogen chamber and is separated by the inner liner, and the outer shell surrounds the outside of the cooling chamber; the liquid hydrogen chamber has a hydrogen evaporation gas outlet; the cooling chamber has an exhaust port; an evaporation gas distribution pipe installed inside the cooling chamber, the inlet of the evaporation gas distribution pipe being connected to the hydrogen evaporation gas outlet; a high-pressure vapor collection pipe installed inside the cooling chamber; and a heat flow compressor unit installed inside the cooling chamber, the heat flow compressor unit comprising multiple parallel... The Knudsen compressors are arranged in series, each comprising multiple Knudsen compression units connected in series. Each Knudsen compression unit includes a cold cavity, a hot cavity, and a first connecting channel. The cold cavity and the hot cavity are connected through the first connecting channel. A low-temperature resistant porous membrane is provided within the first connecting channel. The low-temperature resistant porous membrane includes several microchannels connecting the corresponding cold cavity and the hot cavity. The characteristic size of each microchannel is not greater than the mean free path of hydrogen vapor molecules. A cold cavity heat exchanger is provided within the cold cavity, and a hot cavity heat exchanger is provided within the hot cavity. In each Knudsen compressor, the cold cavity inlet of the first Knudsen compression unit is connected to the vapor distribution pipe. The cold cavity inlet of the cold cavity of the subsequent Knudsen compression unit is connected to the hot cavity outlet of the hot cavity of the preceding Knudsen compression unit via a second connecting channel. The hot cavity outlet of the last Knudsen compression unit is connected to the high-pressure steam collection pipe. A pressure buffer tank is installed inside the refrigeration chamber, and its buffer inlet is connected to the outlet of the high-pressure steam collection pipe. An expander is installed inside the refrigeration chamber, and its expansion inlet is connected to the buffer outlet of the pressure buffer tank. A cold-end steam cooling screen is located between the inner liner and the hot-flow compressor unit, and the cold-end steam cooling screen is equipped with a cold-end pipe, through which the cold-end steam... The inlet is connected to the expansion outlet of the expander; each of the cold cavity heat exchangers is connected to the cold end pipe; a steam cooling screen is disposed between the hot flow compressor unit and the outer casing; the steam cooling screen is provided with a steam pipe, the steam inlet of the steam pipe is connected to the cold end steam outlet of the cold end pipe; and a hot end steam cooling screen is disposed between the hot flow compressor unit and the steam cooling screen, the hot end steam cooling screen is provided with a hot end pipe, the hot end steam inlet of the hot end pipe is connected to the steam outlet of the steam pipe, each of the hot cavity heat exchangers is connected to the hot end pipe; the hot end steam outlet of the hot end pipe is connected to the exhaust port.

[0008] Preferably, in the above technical solution, all the Knudsen compressors are spaced apart around the circumferential direction of the liquid hydrogen chamber, and all the Knudsen compression units of each Knudsen compressor are evenly distributed along the length of the storage tank.

[0009] Preferably, in the above technical solution, the cold cavity and hot cavity of each Knudsen compression unit are arranged opposite to each other, and the hot cavity is located outside the cold cavity when viewed from the inner liner to the outer shell.

[0010] Preferably, the above technical solution further includes: a refrigeration vapor distribution pipe installed inside the refrigeration chamber, the inlet of the refrigeration vapor distribution pipe being connected to the expansion outlet of the expander; the cold end pipes being configured one-to-one with the Knudsen compressor, the cold end vapor inlet of each cold end pipe being connected to the refrigeration vapor distribution pipe; and a refrigeration vapor collecting pipe installed inside the refrigeration chamber, the cold end vapor outlet of each cold end pipe being connected to the refrigeration vapor collecting pipe, and the outlet of the refrigeration vapor collecting pipe being connected to the vapor inlet of the vapor pipe.

[0011] Preferably, the above technical solution further includes: a process vapor distribution pipe installed inside the refrigeration chamber, the inlet of the process vapor distribution pipe being connected to the vapor outlet of the vapor pipe; the hot-end pipes being configured one-to-one with the Knudsen compressor, the hot-end vapor inlet of each hot-end pipe being connected to the process vapor distribution pipe; and a process vapor collecting pipe installed inside the refrigeration chamber, the hot-end vapor outlet of each hot-end pipe being connected to the process vapor collecting pipe, and the outlet of the process vapor collecting pipe being connected to the exhaust port.

[0012] Preferably, in the above technical solution, each of the cold end pipes and each of the hot end pipes are distributed in a U-shaped coil.

[0013] Preferably, in the above technical solution, the vapor pipe is spirally distributed around the liquid hydrogen cavity.

[0014] Preferably, in the above technical solution, both the cold cavity heat exchanger and the hot cavity heat exchanger are finned tube heat exchangers.

[0015] Preferably, the above technical solution further includes a support structure, wherein the support structure is provided between the inner liner and the steam cooling screen, and between the steam cooling screen and the outer shell; and the hot end steam cooling screen and the cold end steam cooling screen are fixed on the support structure between the inner liner and the steam cooling screen.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The liquid hydrogen low-evaporation high-efficiency storage device based on the thermal runoff effect of this invention utilizes the heat infiltrating from the external environment to cool the device, delaying the temperature rise of the hydrogen vapor gas. It operates solely based on the temperature difference between the external environment and the liquid hydrogen without consuming additional high-grade energy, i.e., it utilizes the thermal energy of the external environment for cooling. Compared with conventional active thermal protection technology, it requires no mechanical or electrical energy for cooling, saving high-grade energy. Compared with conventional vapor cooling screen technology, it also has an active cooling function, which can enhance the performance of the vapor cooling screen, further reduce the heat entering the liquid hydrogen chamber, and ensure that the liquid hydrogen is stored under stable conditions. This invention integrates the advantages of active and passive thermal protection technologies while reducing their respective disadvantages. On the one hand, it can achieve active cooling, reducing the impact of heat infiltrating from the external environment on the liquid hydrogen. On the other hand, it can compensate for the disadvantage of passive thermal protection technology, which cannot fully utilize the cooling energy of the hydrogen vapor gas.

[0018] 2. The hot-flow compressor unit of this invention does not require the consumption of high-grade electrical or mechanical energy. It utilizes the heat from the external environment entering the vapor cooling screen and the hot-end vapor cooling screen through the hot-cavity heat exchanger to maintain the hot cavity at a high temperature. The cooling capacity of the hydrogen vapor itself, along with the cooling capacity generated by its flow through the hot-flow compressor unit and the expansion refrigeration, insulates the liquid hydrogen cavity. Simultaneously, during the operation of the hot-flow compressor unit, the hydrogen vapor flows into the cold-cavity heat exchanger to cool the cold cavity and maintain it at a lower temperature. This fully utilizes the heat infiltrating from the external environment and the cooling capacity of the hydrogen vapor, allowing the hydrogen vapor to flow from the cold cavity to the hot cavity through the hot-flow effect, and be pressurized within the Knudsen compressor. The hydrogen vapor flows repeatedly between several cold and hot cavities connected in series within the Knudsen compressor, gradually increasing the pressure to enhance the expansion refrigeration effect, and enabling repeated alternation of hot and cold energy, delaying the time for external heat to enter the liquid hydrogen cavity, which helps in the low-evaporation and high-efficiency storage of liquid hydrogen.

[0019] 3. In the storage device of the present invention, the hydrogen vapor gas flows in series through the cold end vapor cooling screen, the vapor cooling screen and the hot end vapor cooling screen. On the one hand, the increased flow path allows it to absorb more heat from the external environment. On the other hand, the hydrogen vapor gas produces a certain cooling effect after being processed by the hot flow compressor unit, the pressure buffer tank and the expander, which slows down the temperature rise. This also enhances its ability to absorb heat from the external environment. The combination of these two factors can effectively weaken the process of heat continuing to transfer to the liquid hydrogen chamber. The hydrogen vapor gas that has absorbed enough heat is finally discharged to the outside of the storage device, ensuring the safety of low-evaporation and high-efficiency storage of liquid hydrogen.

[0020] 4. The Knudsen compressor using this invention has no moving parts, requires no lubrication, and is safe and reliable in operation. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the structure of a liquid hydrogen low-evaporation high-efficiency storage device based on the thermal runoff effect according to the present invention.

[0022] Figure 2 It is based on the present invention Figure 1 A cross-sectional view along plane AA.

[0023] Figure 3 This is a schematic diagram of the structure of the Knudsen compression unit according to the present invention.

[0024] Figure 4 This is a schematic diagram of the structure of the finned tube heat exchanger according to the present invention.

[0025] Explanation of key figure labels:

[0026] 1-Hydrogen evaporation outlet, 2-Evaporation gas distribution pipe, 3-Cold cavity inlet, 4-Hot cavity outlet, 5-High-pressure steam collecting pipe, 6-Buffer inlet, 7-Pressure buffer tank, 8-Expander, 9-Expansion outlet, 10-Refrigeration vapor distribution pipe, 11-Cold end steam inlet, 12-Cold end steam outlet, 13-Refrigeration vapor collecting pipe, 14-Steam inlet, 15-Steam cooling screen, 16-Steam outlet, 17-Process vapor distribution pipe, 18-Hot end steam inlet, 19-Hot end steam outlet, 20-Process vapor distribution pipe 21-Vacuum collecting pipe, 22-Exhaust port, 23-Liquid hydrogen filling port, 24-Outer shell, 25-Inner liner, 26-Hot flow compressor unit, 26-Knudsen compressor, 2601-Second connecting channel, 2602-Cold cavity, 2603-Cold cavity heat exchanger, 2604-Low temperature resistant porous membrane, 2605-Hot cavity, 2606-Hot cavity heat exchanger, 2607-First connecting channel, 27-Hot end vapor cooling screen, 28-Cold end vapor cooling screen, 29-Supporting structure, 30-Fins, 31-Heat exchange tube. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0028] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0029] Figures 1 to 4 A schematic diagram of a liquid hydrogen low-evaporation high-efficiency storage device based on the thermal runoff effect according to a preferred embodiment of the present invention is shown. The storage device includes a storage tank, an evaporation gas distribution pipe 2, a high-pressure vapor collection pipe 5, a thermal runoff compressor unit 25, a pressure buffer tank 7, an expander 8, a cold-end vapor cooling screen 28, a vapor cooling screen 15, and a hot-end vapor cooling screen 27.

[0030] reference Figures 1 to 4The storage tank, from the inside out, consists of a liquid hydrogen chamber, an inner liner 24, a cooling chamber, and an outer shell 23. The cooling chamber surrounds the liquid hydrogen chamber and is separated by the inner liner 24. The outer shell 23 surrounds the cooling chamber, sealing the entire device to protect its internal structure and components from easy damage. The liquid hydrogen chamber stores liquid hydrogen and has a hydrogen vapor outlet 1 to facilitate the discharge of hydrogen vapor and ensure that the pressure inside the liquid hydrogen chamber remains within a safe range. The cooling chamber has an exhaust port 21 to facilitate the discharge of hydrogen vapor to the outside of the storage device. The liquid hydrogen chamber has a liquid hydrogen filling port 22 for adding liquid hydrogen. The vapor distribution pipe 2 is installed inside the cooling chamber, and its inlet is connected to the hydrogen vapor outlet 1. A high-pressure vapor collecting pipe 5 is installed inside the cooling chamber. A hot-flow compressor unit 25 is installed inside the cooling chamber and operates using the temperature difference between the external environment and the liquid hydrogen as the driving force to prevent heat transfer from the external environment to the liquid hydrogen chamber. The hot flow compressor unit 25 includes multiple Knudsen compressors 26 connected in parallel, and each Knudsen compressor 26 includes multiple Knudsen compression units connected in series. Each Knudsen compression unit includes a cold cavity 2602, a hot cavity 2605, and a first connecting channel 2607, with the cold cavity 2602 and the hot cavity 2605 connected through the first connecting channel 2607. The first connecting channel 2607 contains a low-temperature resistant porous membrane 2604, which includes several microchannels connecting the corresponding cold cavity 2602 and hot cavity 2605. The characteristic size of each microchannel is no greater than the mean free path of hydrogen vapor molecules. When the characteristic size of the microchannel is comparable to or smaller than the mean free path of gas molecules, if a temperature difference is applied across the microchannel, a tangential temperature gradient will exist on the microchannel wall, causing gas molecules near the wall to spontaneously move from the lower temperature end to the higher temperature end; this is the hot flow effect. Under the effect of heat flow, gas molecules continuously gather towards the higher temperature end of the microchannel, increasing its pressure and thus achieving gas pressurization. A cold cavity heat exchanger 2603 is installed in the cold cavity 2602 to cool it, and a hot cavity heat exchanger 2606 is installed in the hot cavity 2605 to heat it. In each Knudsen compressor 26, the cold cavity inlet 3 of the first Knudsen compressor unit's cold cavity 2602 is connected to the evaporator gas distribution pipe 2. The cold cavity inlet 3 of the subsequent Knudsen compressor unit's cold cavity 2602 is connected to the hot cavity outlet 4 of the previous Knudsen compressor unit's hot cavity 2605 via a second connecting channel 2601. The hot cavity outlet 4 of the last Knudsen compressor unit's hot cavity 2605 is connected to the high-pressure steam collecting pipe 5. That is, all Knudsen compressors 26 are connected in parallel between the evaporator gas distribution pipe 2 and the high-pressure steam collecting pipe 5, and all Knudsen compressor units within each Knudsen compressor 26 are connected in series. The hydrogen vapor from the hydrogen vapor outlet 1 flows into each Knudsen compressor 26 through the vapor distribution pipe 2, and is pressurized step by step in each Knudsen compressor 26 to finally obtain hydrogen vapor with higher pressure.A pressure buffer tank 7 is installed inside the refrigeration chamber. The buffer inlet 6 of the pressure buffer tank 7 is connected to the outlet of the high-pressure vapor collecting pipe 5. It is used to store high-pressure hydrogen vapor and stabilize its pressure within a certain range. An expander 8 is installed inside the refrigeration chamber. The expansion inlet of the expander 8 is connected to the buffer outlet of the pressure buffer tank 7. High-pressure hydrogen vapor enters the expander 8 for expansion and cooling, resulting in hydrogen vapor at a lower temperature. A cold-end vapor cooling screen 28 is located between the inner liner 24 and the hot-flow compressor unit 25. The cold-end vapor cooling screen 28 has a cold-end pipe. The cold-end vapor inlet 11 of the cold-end pipe is connected to the expansion outlet 9 of the expander 8. Each cold-chamber heat exchanger 2603 is connected to the cold-end pipe. The lower-temperature hydrogen vapor flows into the cold-end pipe of the cold-end vapor cooling screen 28, which both keeps the liquid hydrogen in the liquid hydrogen chamber at a low temperature and flows into the cold-chamber heat exchanger 2603 to cool the cold chamber 2602. A vapor cooling screen 15 is positioned between the hot-flow compressor unit 25 and the outer casing 23. The vapor cooling screen 15 has a vapor pipe, with its vapor inlet 14 connected to the cold-end vapor outlet 12 of the cold-end pipe. Hydrogen vaporized gas after cooling the cold chamber 2602 flows into the vapor pipe of the vapor cooling screen 15, carrying away the heat transferred from the outer casing 23 to the vapor cooling screen 15, thus increasing the temperature of the hydrogen vaporized gas. A hot-end vapor cooling screen 27 is positioned between the hot-flow compressor unit 25 and the vapor cooling screen 15. The hot-end vapor cooling screen 27 has a hot-end pipe, with its hot-end vapor inlet 18 connected to the vapor outlet 16 of the vapor pipe. Each hot-chamber heat exchanger 2606 is connected to the hot-end pipe. The heated hydrogen vapor flows into the hot-end pipe of the hot-end vapor cooling screen 27, further carrying away the heat that has seeped in from the external environment, delaying the time it takes for heat to enter the liquid hydrogen chamber, and then flows into the hot-end heat exchanger 2606 to heat the hot chamber 2605, maintaining a certain temperature difference between the hot chamber 2605 and the cold chamber 2602. The hot-end vapor outlet 19 of the hot-end pipe is connected to the exhaust port 21, and the hydrogen vapor after heating the hot chamber 2605 is finally discharged to the outside of the storage device through the exhaust port 21. The storage device of this invention utilizes the thermal runoff effect generated by the temperature difference between liquid hydrogen and the external environment to pressurize the hydrogen vapor gas. The hot-end vapor cooling screen 27 is positioned closer to the external environment, while the cold-end vapor cooling screen 28 is positioned closer to the liquid hydrogen cavity. Due to the thermal radiation between the outer shell 23, the vapor cooling screen 15, the hot and cold-end vapor cooling screens, and the inner liner 24, as well as the effect of the hot and cold cavity heat exchanger, there is a temperature difference between the hot and cold-end vapor cooling screens, thus creating a temperature difference between the cold cavity 2602 and the hot cavity 2605. Since the characteristic size of the microchannels of the low-temperature resistant porous membrane 2604 is not greater than the mean free path of the hydrogen vapor gas molecules, a thermal runoff effect will be generated under the action of the temperature difference between the hot and cold cavities. The hydrogen vapor gas molecules will creep from the cold cavity 2602 to the hot cavity 2605 and accumulate in the hot cavity 2605, thereby increasing the pressure of the hydrogen vapor gas.The pressurized hydrogen vapor enters the expander 8 for expansion and cooling. After a certain temperature drop, the hydrogen vapor flows through the cold-end vapor cooling screen 28 to maintain the low temperature of the liquid hydrogen chamber, delaying the transfer of heat from the external environment to the liquid hydrogen chamber. It then flows through the vapor cooling screen 15 to absorb some of the heat that has seeped into the storage device from the external environment, thus increasing its temperature. Next, it flows through the hot-end pipe of the hot-end vapor cooling screen 27 and enters the hot-cavity heat exchanger 2606 to heat the hot-cavity 2605. Along with the flow of the hydrogen vapor, some of the heat that has seeped into the external environment is transferred between the vapor cooling screen 15 and the hot-cavity 2605, driving the hot-flow compressor unit 25. This not only slows the transfer of heat to the liquid hydrogen chamber but also converts some of the heat that has seeped into the external environment into cooling capacity through the hot-flow compressor unit 25 and the expander 8, further delaying the transfer of heat from the external environment to the liquid hydrogen chamber. The hydrogen vapor, which has completed energy transfer and carried most of the heat that has seeped into the external environment, is finally discharged to the outside of the storage device through the exhaust port 21, achieving low-evaporation and high-efficiency storage of liquid hydrogen.

[0031] refer to Figure 1 and Figure 2 In each Knudsen compressor 26, all Knudsen compression units can be evenly distributed along the length of the storage tank or along its circumference. Preferably, all Knudsen compressors 26 are spaced apart around the circumference of the liquid hydrogen chamber, and all Knudsen compression units of each Knudsen compressor 26 are evenly distributed along the length of the storage tank. This arrangement of the Knudsen compressors 26 facilitates the subsequent hydrogen evaporation gas pressurization and expansion-cooling process. The evaporation gas distribution pipe 2 is located at the left end of the storage tank and is distributed around the circumference of the liquid hydrogen chamber, while the high-pressure vapor collecting pipe 5 is located at the right end of the storage tank and is distributed around the circumference of the liquid hydrogen chamber.

[0032] refer to Figures 1 to 3 Each Knudsen compressor unit's cold cavity 2602 and hot cavity 2605 can be arranged in a left-right, front-back, or inner-outer configuration. Preferably, the cold cavity 2602 and hot cavity 2605 of each Knudsen compressor unit are arranged in an inner-outer configuration, that is, when viewed along the direction from the inner liner 24 to the outer shell 23, the hot cavity 2605 is located outside the cold cavity 2602, so that the cold cavity 2602 is close to the cold end vapor cooling screen 28 for easy cooling of the cold cavity 2602; the hot cavity 2605 is close to the hot end vapor cooling screen 27 for easy heating of the hot cavity 2605.

[0033] refer to Figure 1The cold-end pipe can be a single pipe or multiple pipes corresponding one-to-one with the Knudsen compressor 26. Preferably, the storage device further includes a refrigeration vapor distribution pipe 10 and a refrigeration vapor collection pipe 13. The refrigeration vapor distribution pipe 10 is installed inside the refrigeration chamber, and its inlet is connected to the expansion outlet 9 of the expander 8. The cold-end pipes are configured one-to-one with the Knudsen compressor 26, and the cold chamber heat exchanger 2603 of each Knudsen compressor 26 is connected to the corresponding cold-end pipe. The cold-end vapor inlet 11 of each cold-end pipe is connected to the refrigeration vapor distribution pipe 10. The hydrogen vapor after expansion and cooling in the expander 8 first flows into the refrigeration vapor distribution pipe 10, and then is distributed by the refrigeration vapor distribution pipe 10 to each cold-end pipe, providing low-temperature insulation to the liquid hydrogen chamber while also flowing through each cold chamber heat exchanger 2603 to cool the cold chamber 2602. A cooling vapor collection pipe 13 is installed inside the cooling chamber. The cold-end vapor outlet 12 of each cold-end pipe is connected to the cooling vapor collection pipe 13, and the outlet of the cooling vapor collection pipe 13 is connected to the vapor inlet 14 of the vapor pipe. The hydrogen vapor from each cold-end pipe flows into the cooling vapor collection pipe 13, and then flows into the vapor pipe of the vapor cooling screen 15, carrying away some of the heat that seeps in from the external environment. The cooling vapor distribution pipe 10 is located at the left end of the storage tank and is distributed around the circumference of the liquid hydrogen chamber, while the cooling vapor collection pipe 13 is located at the right end of the storage tank and is distributed around the circumference of the liquid hydrogen chamber.

[0034] refer to Figure 1 The hot-end pipe can be a single pipe or multiple pipes corresponding one-to-one with the Knudsen compressor 26. Preferably, the storage device further includes a process vapor distribution pipe 17 and a process vapor collection pipe 20. The process vapor distribution pipe 17 is installed inside the refrigeration chamber, and its inlet is connected to the vapor outlet 16 of the vapor pipe. The hot-end pipes are configured one-to-one with the Knudsen compressor 26, and each Knudsen compressor 26's hot-cavity heat exchanger 2606 is connected to its corresponding hot-end pipe. The hot-end vapor inlet 18 of each hot-end pipe is connected to the process vapor distribution pipe 17. The hydrogen vapor exiting the vapor pipe of the vapor cooling screen 15 increases in temperature as it carries away some of the heat that has seeped into the external environment. It is then distributed to each hot-end pipe through the process vapor collection pipe 20, continuing to carry away some of the heat that has seeped into the external environment and increasing in temperature. Simultaneously, it flows through each hot-cavity heat exchanger 2606, heating the hot cavity 2605. The process vapor collection pipe 20 is installed inside the cooling chamber. The hot-end vapor outlet 19 of each hot-end pipe is connected to the process vapor collection pipe 20, and the outlet of the process vapor collection pipe 20 is connected to the exhaust port 21. The hydrogen vapor from each hot-end pipe flows into the process vapor collection pipe 20, and then from the process vapor collection pipe 20 into the exhaust port 21, and is discharged outside the storage device. The process vapor distribution pipe 17 is located at the left end of the storage tank and is distributed circumferentially around the liquid hydrogen chamber, while the process vapor collection pipe 20 is located at the right end of the storage tank and is distributed circumferentially around the liquid hydrogen chamber.

[0035] refer to Figure 1 and Figure 4 Each cold-end pipe and each hot-end pipe can be in the shape of a straight line, a corrugated shape, or a U-shaped coil. Preferably, each cold-end pipe and each hot-end pipe is distributed in a U-shaped coil to increase the heat exchange area.

[0036] refer to Figure 1 The vapor pipes can be wavy, U-shaped coiled, or spiral in shape. Preferably, the vapor pipes are spirally distributed around the liquid hydrogen chamber and cover the entire vapor cooling screen. This facilitates extending the flow path of the hydrogen vapor, carrying away as much heat as possible from the external environment, maintaining the low-temperature environment inside the tank, and extending the storage time of liquid hydrogen.

[0037] refer to Figure 4 Preferably, both the cold cavity heat exchanger 2603 and the hot cavity heat exchanger 2606 are finned tube heat exchangers, meaning that both include a heat exchange tube 31 and fins 30 wound around the heat exchange tube 31 to enhance the heat exchange effect. The heat exchange tube 31 is connected to either the hot end pipe or the cold end pipe.

[0038] refer to Figure 2 Preferably, the storage device further includes a support structure 29, which is provided between the inner liner 24 and the vapor cooling screen 15, and between the vapor cooling screen 15 and the outer shell 23. The hot-end vapor cooling screen 27 and the cold-end vapor cooling screen 28 are fixed on the support structure 29 between the inner liner 24 and the vapor cooling screen 15. The support structure 29 includes support rods and support blocks. Multiple evenly distributed support rods are provided between the inner liner 24 and the vapor cooling screen 15 along the circumferential direction of the inner liner 24, while the hot-end vapor cooling screen 27 and the cold-end vapor cooling screen 28 are fixed on the support rods. Multiple evenly distributed support blocks are provided between the vapor cooling screen 15 and the outer shell 23 along the circumferential direction of the vapor cooling screen 15. The support structure 29 prevents the outer shell 23, the vapor cooling screen 15, the hot-end vapor cooling screen 27, the cold-end vapor cooling screen 28, and the inner liner 24 from being directly connected to each other. The support structure 29 is made of a material with excellent thermal insulation properties, which can both provide support and minimize the entry of heat from the external environment into the liquid hydrogen chamber.

[0039] In operation, the low-temperature hydrogen vapor is discharged from the liquid hydrogen chamber, passes through the hydrogen vapor outlet 1 into the vapor distribution pipe 2, and then flows into each Knudsen compressor 26 of the hot flow compressor unit 25. Each Knudsen compressor 26 consists of several cold chambers 2602 and hot chambers 2605 connected in series alternately. The temperature difference between the cold chambers 2602 and hot chambers 2605 is used as the driving force to generate a hot flow effect, which pressurizes the hydrogen vapor. The hydrogen vapor enters the cold chamber 2602, and then, under the action of the hot flow effect, passes through the low-temperature resistant porous membrane 2604 and enters the hot chamber 2605. During this process, the temperature rises and the pressure is increased, that is, the pressure of the hydrogen vapor flowing through the Knudsen compressor 26 increases, and the temperature also rises due to the absorption of heat. After being pressurized, the hydrogen vapor flows into the high-pressure steam collector 5 and then into the pressure buffer tank 7, and then passes through the expander 8 for expansion and cooling. The cooled hydrogen vapor is distributed to each cold-end pipe of the cold-end steam cooling screen 28 via the refrigeration vapor distribution pipe 10, cooling the cold-end steam cooling screen 28, and then flows through the cold cavity heat exchanger 2603 to cool the cold cavity 2602. Then, the cold-end vapor from the cold-end vapor outlet 12 of each cold-end pipe of the cold-end steam cooling screen 28 flows into the refrigeration vapor collecting pipe 13, and after being collected by the refrigeration vapor collecting pipe 13, it flows into the spiral vapor pipe of the steam cooling screen 15, carrying away the heat transferred from the outer shell 23 to the steam cooling screen 15. After this series of processes, its temperature rises. Finally, the vapor passes through the vapor outlet 16 of the vapor pipe into the process vapor distribution pipe 17, and is then distributed by the process vapor distribution pipe 17 to each hot-end pipe of the hot-end steam cooling screen 27. After absorbing the heat, the hot-end steam cooling screen 27 passes through the hot cavity heat exchanger 2606 to heat the hot cavity 2605, and then flows into the process vapor collecting pipe 20. The hydrogen vapor, which serves as a medium for energy transfer and carries most of the heat infiltrating from the external environment, is finally discharged from the storage device through exhaust port 21 for further utilization. It should be noted that the liquid hydrogen low-evaporation high-efficiency storage device based on the thermal runoff effect of the present invention cannot reduce the temperature of the hydrogen vapor to the temperature at which it just evaporated from the liquid hydrogen chamber. However, because the device can increase the transfer path of the heat infiltrating from the external environment in the cooling chamber, it delays the time for the heat infiltrating from the external environment to enter the liquid hydrogen chamber, thus enhancing the performance of traditional passive thermal protection in removing the infiltrated heat. In particular, the thermal runoff compressor unit 25 and the expander 8 can convert some of the heat infiltrating from the external environment into cooling, which is equivalent to offsetting some of the infiltrated heat through active cooling. That is, it further delays the transfer of heat infiltrating from the external environment to the liquid hydrogen chamber through active thermal protection. However, at this time, the cooling is powered by the temperature difference between the external environment and the liquid hydrogen, without the need to consume additional high-grade electrical or mechanical energy.

[0040] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A liquid hydrogen low-evaporation, high-efficiency storage device based on the heat flow effect, characterized in that, include: The storage tank comprises, from the inside out, a liquid hydrogen chamber, an inner liner, a cooling chamber, and an outer shell. The cooling chamber surrounds the liquid hydrogen chamber and is separated by the inner liner. The outer shell surrounds the cooling chamber. The liquid hydrogen chamber has a hydrogen vapor outlet. The cooling chamber has an exhaust port. An evaporator gas distribution pipe is installed inside the refrigeration chamber, and the inlet of the evaporator gas distribution pipe is connected to the hydrogen evaporator gas outlet. A high-pressure steam collecting pipe is installed inside the refrigeration chamber; A hot-flow compressor unit is installed within the refrigeration chamber. The hot-flow compressor unit includes multiple Knudsen compressors connected in parallel. Each Knudsen compressor includes multiple Knudsen compression units connected in series. Each Knudsen compression unit includes a cold chamber, a hot chamber, and a first connecting channel. The cold chamber and the hot chamber are connected through the first connecting channel. A low-temperature resistant porous membrane is provided within the first connecting channel. The low-temperature resistant porous membrane includes several microchannels connecting the corresponding cold chamber and the hot chamber. The characteristic size of each microchannel is not greater than the mean free path of hydrogen vapor molecules. A cold chamber heat exchanger is provided within the cold chamber, and a hot chamber heat exchanger is provided within the hot chamber. In each Knudsen compressor, the cold chamber inlet of the first Knudsen compression unit is connected to the vapor distribution pipe. The cold chamber inlet of the subsequent Knudsen compression unit is connected to the hot chamber outlet of the previous Knudsen compression unit through a second connecting channel. The hot chamber outlet of the last Knudsen compression unit is connected to the high-pressure vapor collection pipe. A pressure buffer tank is installed inside the refrigeration chamber, and the buffer inlet of the pressure buffer tank is connected to the outlet of the high-pressure steam collecting pipe. An expander is installed inside the refrigeration chamber, and the expansion inlet of the expander is connected to the buffer outlet of the pressure buffer tank. A cold-end steam cooling screen is disposed between the inner liner and the hot-flow compressor unit. The cold-end steam cooling screen is provided with a cold-end pipe. The cold-end steam inlet of the cold-end pipe is connected to the expansion outlet of the expander. Each of the cold-cavity heat exchangers is connected to the cold-end pipe. A steam cooling screen is disposed between the hot-flow compressor unit and the outer casing; the steam cooling screen is provided with a steam pipe, the steam inlet of which is connected to the cold-end steam outlet of the cold-end pipe; and A hot-end steam cooling screen is disposed between the hot-flow compressor unit and the steam cooling screen. The hot-end steam cooling screen is provided with a hot-end pipe. The hot-end steam inlet of the hot-end pipe is connected to the steam outlet of the steam pipe. Each of the hot chamber heat exchangers is connected to the hot-end pipe. The hot-end steam outlet of the hot-end pipe is connected to the exhaust port.

2. The liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect according to claim 1, characterized in that, All the Knudsen compressors are spaced apart around the circumferential direction of the liquid hydrogen chamber, and all the Knudsen compression units of each Knudsen compressor are evenly distributed along the length of the storage tank.

3. The liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect according to claim 1, characterized in that, The cold and hot chambers of each Knudsen compression unit are arranged opposite each other, with the hot chamber located outside the cold chamber when viewed from the inner liner to the outer shell.

4. The liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect according to claim 1, characterized in that, Also includes: A refrigeration vapor distribution pipe is installed inside the refrigeration chamber, and the inlet of the refrigeration vapor distribution pipe is connected to the expansion outlet of the expander; the cold-end pipes are configured one-to-one with the Knudsen compressor, and the cold-end vapor inlet of each cold-end pipe is connected to the refrigeration vapor distribution pipe; and A refrigeration vapor collection pipe is installed inside the refrigeration chamber. The cold-end vapor outlet of each cold-end pipe is connected to the refrigeration vapor collection pipe, and the outlet of the refrigeration vapor collection pipe is connected to the vapor inlet of the vapor pipe.

5. The liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect according to claim 1, characterized in that, Also includes: A process vapor distribution pipe is installed inside the refrigeration chamber, and the inlet of the process vapor distribution pipe is connected to the vapor outlet of the vapor pipe; the hot end pipes are configured one-to-one with the Knudsen compressor, and the hot end vapor inlet of each hot end pipe is connected to the process vapor distribution pipe; as well as A process vapor collection pipe is installed inside the refrigeration chamber. The hot-end vapor outlet of each hot-end pipe is connected to the process vapor collection pipe, and the outlet of the process vapor collection pipe is connected to the exhaust port.

6. The liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect according to claim 1, characterized in that, Each of the cold-end pipes and each of the hot-end pipes are distributed in a U-shaped coil.

7. The liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect according to claim 1, characterized in that, The steam pipes are spirally distributed around the liquid hydrogen cavity.

8. The liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect according to claim 1, characterized in that, Both the cold cavity heat exchanger and the hot cavity heat exchanger are finned tube heat exchangers.

9. The liquid hydrogen low-evaporation high-efficiency storage device based on the heat flow effect according to claim 1, characterized in that, It also includes a support structure, which is provided between the inner liner and the steam cooling screen, and between the steam cooling screen and the outer shell; and the hot end steam cooling screen and the cold end steam cooling screen are fixed on the support structure between the inner liner and the steam cooling screen.

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