Hydrogen storage container

Abstract

Provided is a hydrogen storage container filled with liquefied hydrogen and having improved insulation performance. A hydrogen storage container according to one aspect of the present invention comprises: an innermost shell forming a hydrogen storage space; an inner shell surrounding the innermost shell to form a first vacuum space between the outer surface of the innermost shell and the inner shell; an outer shell surrounding the inner shell to form a nitrogen storage space between the outer surface of the inner shell and the outer shell; and an outermost shell surrounding the outer shell to form a second vacuum space between the outer surface of the outer shell and the outermost shell.

Description

hydrogen storage tank

[0001] The present invention relates to a hydrogen storage container, and more particularly, to a hydrogen storage container filled with liquefied hydrogen and having improved insulation performance.

[0002] Due to industrial development and population growth, global demand for primary energy continues to rise, and the majority of this energy demand is supplied by fossil fuels such as oil, coal, and natural gas. However, these fossil fuels are finite resources at risk of depletion, and their combustion process emits carbon compounds, contributing to climate change, including global warming.

[0003] As climate change accelerates, the world is exploring ways to reduce reliance on fossil fuels and utilize alternative energy sources. According to the International Energy Agency (IEA), global energy demand is projected to increase by approximately 1% annually through 2030. However, demand for fossil fuels, which currently account for approximately 80% of energy demand, is projected to decline to 60% by 2050.

[0004] Hydrogen is attracting attention as an alternative energy source that can replace fossil fuels. Unlike fossil fuels, which emit carbon compounds during combustion, hydrogen produces electricity through a chemical reaction with oxygen, emitting virtually no pollutants other than water. Furthermore, hydrogen is abundant, making up 75% of the universe's mass, and is a universal element with no regional concentration, preventing depletion. Compared to other alternative energy sources, it offers the advantage of long-term, large-scale storage.

[0005] One method for storing hydrogen is to charge hydrogen in a separate hydrogen storage container, which is divided into two types depending on whether the hydrogen being charged is gaseous or liquid.

[0006] Of the two methods mentioned above, the most commonly used method is the hydrogen gas charging method, which offers the advantage of being easily applicable to products utilizing existing energy sources. However, this method requires an internal pressure of over 700 bar (70 MPa) to meet industrial standards for system gravimetric capacity. Due to this high pressure, the hydrogen storage vessel must be highly rigid and ensure safety during the hydrogen supply process. Furthermore, gaseous hydrogen has a low storage capacity per volume and poses a risk of explosion, requiring extreme care during storage and transport.

[0007] Meanwhile, the method of charging liquefied hydrogen offers the advantages of being able to store it at low pressures of 1 to 3 bar and being more stable than hydrogen gas. Furthermore, hydrogen shrinks by 1 / 800th its volume when changing from gas to liquid, allowing for greater storage capacity and faster charging speeds.

[0008] However, this method of storing liquefied hydrogen requires high insulation performance of the hydrogen storage container because the temperature of the stored liquefied hydrogen must be maintained below 20K (kelvin), which is the vaporization point of liquefied hydrogen.

[0009] Therefore, a hydrogen storage container with improved insulation performance is required for efficient storage of such liquefied hydrogen.

[0010] The purpose of the present invention is to provide a hydrogen storage container filled with liquefied hydrogen and having improved insulation performance.

[0011] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0012] A hydrogen storage container according to one aspect of the present invention may include an innermost shell forming a hydrogen storage space, an inner shell surrounding the innermost shell to form a first vacuum space between the innermost shell and an outer surface of the innermost shell, an outer shell surrounding the inner shell to form a liquid nitrogen storage space between the innermost shell and an outer surface of the inner shell, and an outermost shell surrounding the outer shell to form a second vacuum space between the innermost shell and an outer surface of the outer shell.

[0013] Preferably, the outer surface of the innermost shell may include a first insulating material laminated along the outer surface of the innermost shell and a plurality of first spacers arranged inside the first insulating material in a direction parallel to the lamination direction of the first insulating material.

[0014] Preferably, the outer surface of the outer shell may include a second insulating material laminated along the outer surface of the outer shell and a plurality of second spacers arranged inside the second insulating material in a direction parallel to the lamination direction of the second insulating material.

[0015] Preferably, the inner surface of the innermost shell, the inner shell, the inner surface of the outer shell, and the outermost shell can be formed of aluminum alloy, high-density polyethylene, polyamide, titanium, stainless steel, carbon fiber reinforced plastic, or glass fiber reinforced plastic material.

[0016] Preferably, the first insulation material and the second insulation material are formed by laminating a plurality of aluminum foils, and the first spacer and the second spacer can be formed of glass fiber or polyurethane foam material.

[0017] Preferably, liquid hydrogen may be filled into the hydrogen storage space so that the temperature of the hydrogen storage space is maintained below the vaporization point of liquid hydrogen, and liquid nitrogen may be filled into the liquid nitrogen storage space so that the temperature of the liquid nitrogen storage space is maintained below the vaporization point of liquid nitrogen.

[0018] Preferably, the liquefied hydrogen charged into the hydrogen storage space can be charged at a temperature lower than the vaporization point of the liquefied hydrogen.

[0019] Preferably, the liquefied hydrogen charged into the hydrogen storage space can be charged at a temperature in the range of 1K to 10K lower than the vaporization point of the liquefied hydrogen.

[0020] Preferably, the volume of liquid nitrogen filled in the liquid nitrogen storage space may be 0.001 to 1 times the volume of liquid hydrogen filled in the hydrogen storage space.

[0021] Preferably, the volume of liquefied hydrogen filled in the hydrogen storage space may be 50 L or more.

[0022] Preferably, the hydrogen storage container comprises the innermost shell and a second storage container including the inner shell, the outer shell and a first storage container including the outermost shell, and a joining cover joined to the first storage container, and can be manufactured in such a way that the second storage container, which has been manufactured in advance, is inserted into the first storage container, which has been manufactured in advance, and then the joining cover is joined.

[0023] A hydrogen storage container according to one embodiment of the present invention is configured with a quadruple insulation structure in which an innermost shell, an inner shell, an outer shell, and an outermost shell are arranged between a hydrogen storage space and the outside, thereby improving insulation performance and minimizing the impact of external impact on the hydrogen storage space.

[0024] In addition, according to one embodiment of the present invention, the outer surface of the innermost shell includes a first insulating material laminated along the outer surface of the innermost shell and a plurality of first spacers arranged inside the first insulating material in a direction parallel to the lamination direction of the first insulating material, so that the insulating performance of the innermost shell can be improved.

[0025] In addition, according to one embodiment of the present invention, the inner surface of the innermost shell, the inner shell, the inner surface of the outer shell, and the outermost shell are formed of an aluminum alloy material, the first insulation material and the second insulation material are formed by laminating a plurality of aluminum foils, and the first spacer and the second spacer are formed of a fiber glass material, whereby the hydrogen storage container can be made lighter and the rigidity and insulation performance of the hydrogen storage container can be improved.

[0026] In addition, according to one embodiment of the present invention, liquid hydrogen is charged into the hydrogen storage space so that the temperature of the hydrogen storage space is maintained below the vaporization point of liquid hydrogen, and liquid nitrogen is charged into the liquid nitrogen storage space so that the temperature of the liquid nitrogen storage space is maintained below the vaporization point of liquid nitrogen, so that the liquid nitrogen absorbs the heat energy transferred to the outer shell by the latent heat of vaporization, thereby reducing heat transfer to the hydrogen storage space where the liquid hydrogen is stored, and thus the storage time of the liquid hydrogen can be increased.

[0027] In addition, according to one embodiment of the present invention, the liquid hydrogen charged into the hydrogen storage space is charged at a temperature lower than the vaporization point of the liquid hydrogen, thereby delaying the time at which the liquid hydrogen begins to vaporize, thereby allowing the liquid hydrogen to be fully stored before the liquid hydrogen vaporizes.

[0028] In addition, various additional effects can be achieved through various embodiments of the present invention. These various effects of the present invention will be described in detail in each embodiment, or descriptions of effects easily understandable to those skilled in the art will be omitted.

[0029] FIG. 1 is a perspective view of a hydrogen storage container according to one embodiment of the present invention.

[0030] Figure 2 is a cross-sectional view of a hydrogen storage container according to one embodiment of the present invention.

[0031] Figure 3 is an enlarged view of part A of Figure 2.

[0032] Figure 4 is a drawing showing the insulation structure of a hydrogen storage container with double, triple, and quadruple insulation structures.

[0033] Figure 5 is a graph comparing the temperature changes over time of liquid nitrogen and liquefied hydrogen in the hydrogen storage containers with double, triple, and quadruple insulation structures of Figure 4.

[0034] Figure 6 is a drawing showing the insulation structure of a hydrogen storage container with a quadruple insulation structure and a hydrogen storage container using spray-on foam insulation.

[0035] Figure 7 is a graph comparing the temperature changes over time of liquid nitrogen and liquefied hydrogen in a hydrogen storage container with a quadruple insulation structure of Figure 6 and a hydrogen storage container using spray-on foam insulation.

[0036] Figure 8 is a graph comparing the temperature change of liquefied hydrogen over time according to the temperature of liquefied hydrogen charged into a hydrogen storage container according to one embodiment of the present invention.

[0037] Figure 9 is a graph comparing the change in heat transfer over time and temperature of liquefied hydrogen charged into a hydrogen storage container according to one embodiment of the present invention.

[0038] Figure 10 is a graph comparing the storage time of liquefied hydrogen according to changes in the volume of liquefied hydrogen filled in a hydrogen storage container according to one embodiment of the present invention.

[0039] Fig. 11 is a drawing showing a method of manufacturing a hydrogen storage container according to one embodiment of the present invention.

[0040] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concepts of terms to best explain his or her invention, they should be interpreted in a way that aligns with the technical spirit of the present invention.

[0041] Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and it should be understood that there may be various equivalents and modified examples that can replace them at the time of this application.

[0042] FIG. 1 is a perspective view of a hydrogen storage container (10) according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of a hydrogen storage container (10) according to one embodiment of the present invention.

[0043] Referring to FIGS. 1 and 2, a hydrogen storage container (10) according to one embodiment of the present invention may include an innermost shell (100), an inner shell (200), an outer shell (300), and an outermost shell (400).

[0044] The above innermost shell (100) can form a hydrogen storage space (101).

[0045] The inner shell (200) can surround the inner most shell (100) to form a first vacuum space (201) between the inner most shell (100) and the outer surface of the inner most shell (100).

[0046] The outer shell (300) can surround the inner shell (200) to form a liquid nitrogen storage space (301) between the outer surface of the inner shell (200).

[0047] The above outermost shell (400) can surround the outer shell (300) to form a second vacuum space (401) between the outer surface of the outer shell (300).

[0048] By this configuration, the hydrogen storage container (10) is configured as a quadruple insulation structure in which an innermost shell (100), an inner shell (200), an outer shell (300), and an outermost shell (400) are arranged between the hydrogen storage space (101) and the outside, thereby improving insulation performance and minimizing the impact of external impact on the hydrogen storage space (101). This quadruple insulation structure can act as an important factor in improving the insulation performance of the hydrogen storage container (10), and a detailed description thereof will be provided later.

[0049] In addition, the hydrogen storage container (10) may further include a hydrogen charging nozzle (500) and a nitrogen charging nozzle (600).

[0050] The hydrogen charging nozzle (500) may be coupled to the innermost shell (100) to form a passage through which hydrogen moves between the outside and the hydrogen storage space (101). In addition, although not shown, a boss part surrounding the hydrogen charging nozzle (500) may be formed in the innermost shell (100).

[0051] The nitrogen charging nozzle (600) may be coupled to the outer shell (300) to form a passage through which nitrogen moves between the outside and the liquid nitrogen storage space (301). In addition, although not shown, a boss portion surrounding the nitrogen charging nozzle (600) may be formed on the outer shell (300).

[0052] In addition, the first vacuum space (201) and the second vacuum space (401) can form a vacuum. Although not shown, a port connected to a vacuum pump may be provided in the first vacuum space (201) and the second vacuum space (401). In addition, the first vacuum space (201) and the second vacuum space (401) can be formed by a vacuum pump at 10 -10 It can be configured to receive a pressure of bar. Accordingly, heat transfer by convection and conduction of gas in the first vacuum space (201) and the second vacuum space (401) can be blocked.

[0053] And, the liquid nitrogen storage space (301) may be filled with a refrigerant. As an example, the refrigerant may be liquid nitrogen (N2).

[0054] Figure 3 is an enlarged view of part A of Figure 2.

[0055] Referring to FIG. 3, the outer surface (120) of the innermost shell may include a first insulating material (121) and a plurality of first spacers (122).

[0056] The above first insulation material (121) can be laminated along the outer surface (120) of the innermost shell.

[0057] The above first spacer (122) can be placed inside the first insulating material (121) in a direction parallel to the lamination direction of the first insulating material (121).

[0058] At this time, the first insulation material (121) and the first spacer (122) can form a multi-layer thin-film insulation material (MLI; Multi Layer Insulation).

[0059] Additionally, the outer surface (320) of the outer shell may include a second insulating material (321) and a plurality of second spacers (322).

[0060] The above second insulating material (321) can be laminated along the outer surface (320) of the outer shell.

[0061] The second spacer (322) may be arranged inside the second insulation material (321) in a direction parallel to the lamination direction of the second insulation material (321). In addition, the second insulation material (321) and the second spacer (322) may form a multilayer thin film insulation material, like the first insulation material (121) and the first spacer (122).

[0062] Hereinafter, with reference to FIG. 3, the heat flux of each section of a hydrogen storage vessel (10) configured with a quadruple insulation structure according to one embodiment of the present invention will be described in detail. It is assumed that the heat flux of each section of the hydrogen storage vessel (10) described below is measured in a steady state, in which the temperature of each shell is the same as that of the adjacent layer, and in an ideal vacuum in which there is no heat transfer by convection.

[0063] First, the heat flux q1 from the outermost shell (400) to the outer surface (320) of the outer shell can be expressed by the following mathematical expression 1. At this time, since the temperature of each shell is assumed to be the same as the adjacent layer as described above, the temperature of the outermost shell (400) is assumed to be the same as the external temperature. In addition, since the second vacuum space (401) is assumed to be an ideal vacuum, the following mathematical expression 1 only considers the heat flux due to thermal radiation.

[0064] [Mathematical Formula 1]

[0065]

[0066] Here, A represents the surface area of ​​the outer surface (320) of the outer shell, σ represents the Stefan-Boltzmann constant, T0 represents the temperature of the outermost shell (400), T1 represents the temperature of the outer surface (320) of the outer shell, e0 represents the emissivity of the outermost shell (400), and e1 represents the emissivity of the outer surface (320) of the outer shell.

[0067] In the above mathematical expression 1, the decrease in the surface area of ​​the outer surface (320) of the outer shell and the decrease in the emissivity of the outer surface (320) of the outer shell and the outermost shell (400) cause a decrease in the heat flux q1 from the outermost shell (400) to the outer shell (300), so it can be confirmed that the miniaturization of the hydrogen storage container (10) and the material of the second insulation material (321) are important factors in improving the insulation performance of the hydrogen storage container (10).

[0068] And, the heat flux from the outer surface (320) of the outer shell to the inner surface (310) of the outer shell is divided into q2, which is a heat flux due to thermal radiation, and q3, which is a heat flux due to thermal conduction. At this time, the heat flux q2 can be expressed by the following mathematical expression 2.

[0069] [Equation 2]

[0070]

[0071] In addition, the heat flux q3 can be expressed by the following mathematical expression 3.

[0072] [Equation 3]

[0073]

[0074] Here, A is the surface area of ​​the inner surface (310) of the outer shell, A spc1 is the outer surface area of ​​the second spacer (322), T1 is the temperature of the outer surface (320) of the outer shell, T2 is the temperature of the inner surface (310) of the outer shell, e1 is the emissivity of the outer surface (320) of the outer shell, e2 is the emissivity of the inner surface (310) of the outer shell, k spc1 The thermal conductivity of the second spacer (322) is L spc1 refers to the length of the second spacer (322).

[0075] Referring to the above mathematical expressions 2 and 3, a decrease in the surface area of ​​the inner surface (310) of the outer shell, a decrease in the emissivity of the outer surface (320) of the outer shell and the inner surface (310) of the outer shell, and a decrease in the length of the second spacer (322) cause a decrease in the heat fluxes q2 and q3, and therefore, it can be confirmed that miniaturization of the hydrogen storage container (10) and reduction in insulation thickness are important factors in improving the insulation performance of the hydrogen storage container (10).

[0076] In addition, the heat flux q4 from the inner surface (310) of the outer shell to the inner shell (200) can be expressed by the following mathematical expression 4. In addition, assuming that the liquid nitrogen storage space (301) is filled with a refrigerant, the following mathematical expression 4 only considers the heat flux due to heat conduction.

[0077] [Equation 4]

[0078]

[0079] Here, A is the surface area of ​​the inner shell (200), k LN2 is the thermal conductivity of the refrigerant filled in the liquid nitrogen storage space (301), T2 is the temperature of the inner surface (310) of the outer shell, T3 is the temperature of the inner shell (200), L LN2 refers to the distance from the inner surface (310) of the outer shell to the inner shell (200).

[0080] Referring to the above mathematical expression 4, the lower the thermal conductivity of the refrigerant filled in the liquid nitrogen storage space (301) and the shorter the distance from the inner surface (310) of the outer shell to the inner shell (200), the lower the heat flux q4, so it can be confirmed that the miniaturization of the hydrogen storage container (10) and the refrigerant of the liquid nitrogen storage space (301) are important factors in improving the insulation performance of the hydrogen storage container (10).

[0081] In addition, the heat flux q5 from the inner shell (200) to the outer surface (120) of the innermost shell can be expressed by the following mathematical expression 5. At this time, since the first vacuum space (201) is assumed to be an ideal vacuum, the following mathematical expression 5 only considers the heat flux due to thermal radiation.

[0082] [Equation 5]

[0083]

[0084] A represents the surface area of ​​the outer surface (120) of the innermost shell, T3 represents the temperature of the inner shell (200), T4 represents the temperature of the outer surface (120) of the innermost shell, e3 represents the emissivity of the inner shell (200), and e4 represents the emissivity of the outer surface (120) of the innermost shell.

[0085] Referring to the above mathematical expression 5, it can be confirmed that the miniaturization of the hydrogen storage container (10) and the material of the first insulating material (121) are important factors in improving the insulation performance of the hydrogen storage container (10).

[0086] In addition, the heat flux from the outer surface (120) of the innermost shell to the inner surface (110) of the innermost shell is divided into q6, which is a heat flux due to thermal radiation, and q7, which is a heat flux due to thermal conduction. At this time, the heat flux q6 can be expressed by the following mathematical expression 6.

[0087] [Equation 6]

[0088]

[0089] In addition, the heat flux q7 can be expressed by the following mathematical expression 7.

[0090] [Equation 7]

[0091]

[0092] Here, A is the surface area of ​​the inner surface (110) of the innermost shell, A spc2is the outer surface area of ​​the first spacer (122), T4 is the temperature of the outer surface (120) of the innermost shell, T5 is the temperature of the inner surface (110) of the innermost shell, e4 is the emissivity of the outer surface (120) of the innermost shell, e5 is the emissivity of the inner surface (110) of the innermost shell, k spc2 is the thermal conductivity of the first spacer (122), L spc2 refers to the length of the first spacer (122).

[0093] Referring to the above mathematical expressions 6 and 7, it can be confirmed that miniaturization of the hydrogen storage container (10) and reduction of insulation thickness are important factors in improving the insulation performance of the hydrogen storage container (10).

[0094] In addition, the inner surface (110) of the innermost shell, the inner shell (200), the inner surface (310) of the outer shell, and the outermost shell (400) may be formed of aluminum alloy, high density polyethylene (HDPE), polyamide, titanium, stainless steel, carbon fiber reinforced plastic (CFRP), or glass fiber reinforced plastic (GFRP).

[0095] Since the metals and synthetic resins, including high-density polyethylene, polyamide, titanium, etc., including these aluminum alloys, have low specific weight and high rigidity-to-weight ratio compared to other metals and synthetic resins, the hydrogen storage container (10) can be made lighter through this configuration while simultaneously improving the rigidity of the hydrogen storage container (10).

[0096] Alternatively, the inner surface (110) of the innermost shell, the inner shell (200), the inner surface (310) of the outermost shell, and the outermost shell (400) may include a liner made of a non-metallic material and a fiber-reinforced composite material. In this case, the liner may maintain the sealing and shape of the contents, and may be manufactured by winding the outer surface of the liner with a fiber-reinforced composite material. The liner may be made of a high-density polyethylene (HDPE) material.

[0097] In addition, the first insulation material (121) and the second insulation material (321) may be formed by laminating a plurality of aluminum foils. In addition, the first spacer (122) and the second spacer (322) may be formed of fiber glass or polyurethane foam material.

[0098] Since the laminated aluminum foil has excellent insulation performance, the glass fiber has excellent insulation performance and high rigidity, and the polyurethane foam has excellent insulation performance and adhesion, the insulation performance of the hydrogen storage container (10) can be improved through this configuration. In addition, the first vacuum space (201) and the second vacuum space (401) forming a vacuum can effectively block heat transfer by convection and conduction of gas, but cannot block most radiation heat transfer. The aluminum foil can minimize radiation heat transfer by retroreflecting more than 95% of the infrared radiation caused by such radiation heat transfer.

[0099] More specifically, since the emissivity of the outer surface (320) of the outer shell corresponds to e1 of the above mathematical expression 1, and the emissivity of the outer surface (120) of the innermost shell corresponds to e4 of the above mathematical expression 5, the lower the emissivity of the outer surface (120) of the innermost shell, which is affected by the material of the first insulating material (121), and the lower the emissivity of the outer surface (320) of the outer shell, which is affected by the material of the second insulating material (321), the more the heat fluxes q1 and q5 can be reduced. In addition, aluminum foil can have a low emissivity of approximately 0.05. Accordingly, by lowering the emissivity of the outer surface (120) of the innermost shell and the outer surface (320) of the outer shell through the first insulation material (121) and the second insulation material (321) formed by laminating such aluminum foils, the heat flux q1 from the outermost shell (400) to the outer surface (320) of the outer shell and the heat flux q5 from the inner shell (200) to the outer surface (120) of the innermost shell can be reduced. Through this configuration, the insulation performance of the hydrogen storage container (10) can be improved.

[0100] Alternatively, the first insulation material (121) and the second insulation material (321) may be formed of a plurality of aluminum foils and a plurality of glass wools. In this case, the first insulation material (121) and the second insulation material (321) may be formed in a structure in which aluminum foils and glass wools are alternately laminated.

[0101] In addition, in the embodiment of the present invention, liquid hydrogen (H2) may be filled into the hydrogen storage space (101) so that the temperature of the hydrogen storage space (101) is maintained below the vaporization point of liquid hydrogen (H2), and liquid nitrogen (N2) may be filled into the liquid nitrogen storage space (301) so that the temperature of the liquid nitrogen storage space (301) is maintained below the vaporization point of liquid nitrogen (N2). At this time, the vaporization point of the liquid hydrogen (H2) may be 20K, and the vaporization point of the liquid nitrogen (N2) may be 77K.

[0102] By this configuration, liquid nitrogen (N2) absorbs the heat energy transferred to the outer shell (300) by latent heat of vaporization, thereby reducing heat transfer to the hydrogen storage space (101) where liquid hydrogen (H2) is stored, thereby increasing the storage time of liquid hydrogen (H2).

[0103] In addition, the liquid nitrogen storage space (301) filled with the liquid nitrogen (N2) is formed between the inner shell (200) and the outer shell (300) so as to be located between the first vacuum space (201) and the second vacuum space (401), so that heat transfer to the liquid nitrogen storage space (301) is minimized, and the evaporation rate of the liquid nitrogen (N2) can be reduced.

[0104] Fig. 4 is a drawing illustrating the insulation structure of a hydrogen storage container having a double, triple, and quadruple insulation structure. More specifically, Fig. 4 (a) is a drawing illustrating the insulation structure of a hydrogen storage container having a double insulation structure, Fig. 4 (b) is a drawing illustrating the insulation structure of a hydrogen storage container having a triple insulation structure, and Fig. 4 (c) is a drawing illustrating the insulation structure of a hydrogen storage container having a quadruple insulation structure.

[0105] At this time, the hydrogen storage container having the double, triple and quadruple insulation structure may have the properties shown in Table 1 below.

[0106] Properties Value Layer density 40 layer / 4mm Density 320 kg / m 3 Pressure 10 -10 barsEffective conductivity 0.0437 W / mKEffective emissivity 0.00925

[0107] Fig. 5 is a graph comparing the temperature changes over time of liquid nitrogen and liquefied hydrogen in hydrogen storage containers with double, triple, and quadruple insulation structures of Fig. 4. More specifically, Fig. 5 is a graph showing the temperature changes over time of liquid nitrogen and liquefied hydrogen in hydrogen storage containers with double, triple, and quadruple insulation structures of Fig. 4, which have the same properties as Table 1, measured to confirm the insulation performance according to the insulation structure.

[0108] In Fig. 5, the red solid line represents the temperature of liquid hydrogen over time in a hydrogen storage vessel with a double insulation structure, the red dotted line represents the temperature of liquid hydrogen and adjacent insulation over time in a hydrogen storage vessel with a double insulation structure, the blue solid line represents the temperature of liquid hydrogen over time in a hydrogen storage vessel with a triple insulation structure, the blue dotted line represents the temperature of liquid nitrogen over time in a hydrogen storage vessel with a triple insulation structure, the yellow solid line represents the temperature of liquid hydrogen over time in a hydrogen storage vessel with a quadruple insulation structure, and the yellow dotted line represents the temperature of liquid nitrogen over time in a hydrogen storage vessel with a quadruple insulation structure.

[0109] At this time, the initial conditions and results for measuring the temperature change over time of liquid nitrogen and liquefied hydrogen in the hydrogen storage container with the double, triple, and quadruple insulation structures can be confirmed as shown in Table 2 below.

[0110] Adiabatic structure emissivity (ε) Initial volume of liquid hydrogen (L) Initial volume of liquid nitrogen (L) Complete evaporation time of liquid nitrogen (h) Complete evaporation time of liquid hydrogen (h) 2 times 9.25 x 10 -3 12NA00.53 medium 9.25x10 -3 1212105.63.74middle9.25x10 -3 1212422.4533

[0111] Referring to FIGS. 4, 4, 5, and Table 2, in the case of a hydrogen storage vessel with a double insulation structure, it can be confirmed that the stored liquid hydrogen completely evaporates about 30 minutes after measurement, and the temperature rises above the vaporization point. In addition, in the case of a hydrogen storage vessel with a triple insulation structure, it can be confirmed that the stored liquid hydrogen completely evaporates about 3.7 hours after measurement, and the temperature rises above the vaporization point. Finally, in the case of a hydrogen storage vessel with a quadruple insulation structure, it can be confirmed that the stored liquid hydrogen completely evaporates about 533 hours after measurement, and the temperature rises above the vaporization point.

[0112] Through these measurement results, it can be confirmed that the quadruple insulation structure is far superior to the double or triple insulation structure in terms of hydrogen storage and insulation capabilities of the hydrogen storage vessel. In addition, in the case of the triple or quadruple insulation structure, it can be confirmed that the temperature of the stored liquid hydrogen rises rapidly after a certain period of time from the point where the stored liquid nitrogen has completely evaporated, thereby confirming that the charging of liquid nitrogen has the effect of preventing the temperature rise of the stored liquid hydrogen.

[0113] Fig. 6 is a drawing illustrating the insulation structure of a hydrogen storage container having a quadruple insulation structure and a hydrogen storage container using spray-on foam insulation (SOFI). More specifically, Fig. 6 (a) is a drawing illustrating the insulation structure of a hydrogen storage container having a quadruple insulation structure, and Fig. 6 (b) is a drawing illustrating the insulation structure of a hydrogen storage container using spray-on foam insulation.

[0114] At this time, the hydrogen storage container with the above-mentioned four-layer insulation structure and the hydrogen storage container using the spray-on foam insulation have the properties as shown in Table 1 above, and the spray-on foam insulation may have the properties as shown in Table 3 below.

[0115] Properties Value Thermal conductivity 0.039 W / mK Specific heat capacity 1400 J / kg.K Density 7.5 kg / m 3

[0116] Fig. 7 is a graph comparing the temperature changes over time of liquid nitrogen and liquid hydrogen in a hydrogen storage container having a quadruple insulation structure of Fig. 6 and a hydrogen storage container using spray-on foam insulation. More specifically, Fig. 7 (a) is a graph comparing the temperature changes over time of liquid nitrogen and liquid hydrogen in a hydrogen storage container when 12 L of liquid hydrogen is filled, and Fig. 7 (b) is a graph comparing the temperature changes over time of liquid nitrogen and liquid hydrogen in a hydrogen storage container when 5 L of liquid hydrogen is filled.

[0117] In Fig. 7, the yellow solid line represents the temperature change over time of liquid hydrogen in a hydrogen storage container having a quadruple insulation structure, the yellow dotted line represents the temperature change over time of liquid nitrogen in a hydrogen storage container having a quadruple insulation structure, the red solid line represents the temperature change over time of liquid hydrogen in a hydrogen storage container using spray-on foam insulation having a thickness of 4.9 cm or 4.3 cm, the red dotted line represents the temperature change over time of spray-on foam insulation in a hydrogen storage container using spray-on foam insulation having a thickness of 4.9 cm or 4.3 cm, the blue solid line represents the temperature change over time of liquid hydrogen in a hydrogen storage container using spray-on foam insulation having a thickness of 55 cm or 45 cm, and the blue dotted line represents the temperature change over time of spray-on foam insulation in a hydrogen storage container using spray-on foam insulation having a thickness of 55 cm or 45 cm.

[0118] At this time, the initial conditions and results of the measurement of the temperature change over time of liquid nitrogen and liquefied hydrogen in the hydrogen storage container with the above-mentioned four-layer insulation structure and the hydrogen storage container using spray-on foam insulation can be confirmed as shown in Table 4 below.

[0119] Adiabatic structureEmissivity(ε)Initial volume of liquid hydrogen(L)Initial volume of liquid nitrogen(L)Insulation thickness(cm)Complete evaporation time of liquid hydrogen(days)Complete evaporation time of liquid nitrogen(days)4-19.25x10 -3 12124.922.217.6SOFI-19.25x10 -3 12NA4.94.9NASOFI-29.25x10 -3 12NA5521.1NA4-29.25x10 -3 554.316.212.2SOFI-39.25x10 -3 5NA4.33.7NASOFI-49.25x10 -3 5NA4516.1NA

[0120] Referring to FIGS. 6 and 7 and Table 4, when comparing the complete evaporation time of liquefied hydrogen stored in a hydrogen storage container with a quadruple insulation structure having the same insulation thickness and a hydrogen storage container using spray-on foam insulation, it can be confirmed that the hydrogen storage container with a quadruple insulation structure shows an evaporation time that is approximately 4.4 times longer than the hydrogen storage container using spray-on foam insulation.

[0121] Additionally, it can be confirmed that in order for the liquid hydrogen to completely evaporate in a time similar to that of a hydrogen storage container with a quadruple insulation structure, a hydrogen storage container using spray-on foam insulation with an insulation thickness more than 10 times that of a hydrogen storage container with a quadruple insulation structure is required.

[0122] These measurement results confirm that the quadruple-insulated structure significantly outperforms spray-on foam insulation in terms of hydrogen storage and insulation capabilities. Furthermore, the quadruple-insulated structure allows for smaller and lighter hydrogen storage containers, as the insulation thickness required to achieve the desired performance is reduced.

[0123] FIG. 8 is a graph comparing the temperature change of liquid hydrogen (H2) over time according to the temperature of liquid hydrogen (H2) charged into a hydrogen storage container (10) according to one embodiment of the present invention. More specifically, (a) of FIG. 8 is a graph comparing the evaporation time of liquid hydrogen (H2) according to the temperature of the liquid hydrogen (H2) charged into a hydrogen storage container (10) charged with 12 L of liquid hydrogen (H2) and 5 L of liquid nitrogen (N2), and (b) of FIG. 8 is a graph illustrating an enlarged portion of (a) of FIG.

[0124] Fig. 9 is a graph comparing the change in heat transfer over time according to the temperature of liquefied hydrogen (H2) filled in a hydrogen storage container (10) according to one embodiment of the present invention. More specifically, for a hydrogen storage container (10) having a quadruple insulation structure filled with 12 L of liquefied hydrogen (H2) and 5 L of liquid nitrogen (N2), the heat transfer over time from the inner shell (200) to the innermost shell (100) is represented by a solid line, and the heat transfer over time from the outermost shell (400) to the outer shell (300) is represented by a dotted line.

[0125] Referring to FIGS. 8 and 9, the liquid hydrogen (H2) charged into the hydrogen storage space (101) can be charged at a temperature lower than the vaporization point of the liquid hydrogen (H2).

[0126] By this configuration, by delaying the time at which the liquid hydrogen (H2) charged in the hydrogen storage space (101) begins to vaporize, the hydrogen storage container (10) can completely store the liquid hydrogen (H2) before the liquid hydrogen (H2) begins to vaporize.

[0127] More specifically, referring to FIG. 8, in the case of liquid hydrogen (H2) charged at a temperature of the vaporization point of liquid hydrogen (H2) indicated by a pink solid line, it can be confirmed that vaporization of liquid hydrogen (H2) starts from the start of measurement. In addition, in the case of liquid hydrogen (H2) charged at a temperature lower than the vaporization point of liquid hydrogen (H2) indicated by solid lines in colors other than pink, it can be confirmed that the lower the temperature at the time of charging liquid hydrogen (H2), the later the liquid hydrogen (H2) starts vaporizing, and the increase in the vaporization delay time of liquid hydrogen (H2) due to the decrease in the temperature of liquid hydrogen (H2) gradually slows down.

[0128] At this time, in the case of liquid hydrogen (H2) charged at a temperature 1K lower than the vaporization point of liquid hydrogen (H2) shown by the sky blue solid line, it can be confirmed that vaporization of liquid hydrogen (H2) does not occur for about 42 hours, and in the case of liquid hydrogen (H2) charged at a temperature 5K lower than the vaporization point of liquid hydrogen (H2) shown by the black solid line, it can be confirmed that vaporization of liquid hydrogen (H2) does not occur for about 70 hours.

[0129] Accordingly, while securing sufficient vaporization delay time of the liquid hydrogen (H2), taking into account the slowdown in the increase in delay time due to the decrease in temperature of the liquid hydrogen (H2), the liquid hydrogen (H2) filled in the hydrogen storage space (101) can be filled at a temperature in the range of 1K to 10K lower than the vaporization point of the liquid hydrogen (H2).

[0130] In addition, referring to FIG. 9, through heat transfer from the inner shell (200) shown in solid lines to the innermost shell (100), it can be confirmed that the liquefied hydrogen (H2) stored in the hydrogen storage space (101) steadily absorbs heat and completely vaporizes when the heat transfer rate from the inner shell (200) to the innermost shell (100) reaches the peak point, thereby not absorbing heat.

[0131] At this time, the time for the heat transfer rate from the inner shell (200) to the innermost shell (100) to reach the peak point tends to increase as the temperature of the liquid hydrogen (H2) charged into the hydrogen storage space (101) decreases. Therefore, through a configuration in which the liquid hydrogen (H2) charged into the hydrogen storage space (101) is charged at a temperature lower than the vaporization point of the liquid hydrogen (H2), there is also an effect of increasing the storage time of the liquid hydrogen (H2) stored in the hydrogen storage space (101).

[0132] FIG. 10 is a graph comparing the storage time of liquid hydrogen (H2) according to the change in the volume of liquid hydrogen (H2) filled in a hydrogen storage container (10) according to one embodiment of the present invention. More specifically, FIG. 10 (a) is a graph showing the volume of liquid nitrogen (N2) and liquid hydrogen (H2) that satisfy the corresponding storage time for three solid lines classified according to the storage time of liquid hydrogen (H2). At this time, the horizontal axis of the graph represents the volume of liquid hydrogen (H2) in L (liter), and the vertical axis of the graph represents the value obtained by multiplying the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2) by 100. FIG. 10 (b) is a graph showing the storage time and complete evaporation time of liquid hydrogen (H2) according to the volume of liquid hydrogen (H2) when the volumes of liquid nitrogen (N2) and liquid hydrogen (H2) are the same.

[0133] Referring to (a) of Fig. 10, it can be confirmed that as the volume of liquid hydrogen (H2) charged into the hydrogen storage container (10) increases and as the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2) increases, the storage time of liquid hydrogen (H2) increases. In addition, it can be confirmed that the increase in the storage time of liquid hydrogen (H2) due to the increase in the volume of liquid nitrogen (N2) and the increase in the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2) gradually slows down.

[0134] At this time, it can be confirmed that the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2) for implementing the target storage time of liquid hydrogen (H2) gradually decreases as the capacity of liquid hydrogen (H2) increases. In addition, considering that the storage capacity of liquid hydrogen (H2) required for hydrogen vehicles, which are the target use of the hydrogen storage container (10), is typically 50 L or more, the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2) for implementing the target storage time of liquid hydrogen (H2) will gradually decrease as the capacity of liquid hydrogen (H2) increases, and therefore, it is preferable that the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2) is 0.001 times or more. In addition, considering the slowdown in the increase in the storage time of liquid hydrogen (H2) due to the increase in the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2), even if the volume of the charged liquid hydrogen (H2) is considered to be a conservative figure of 1 L, it is preferable that the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2) be 1 or less so that the storage time of liquid hydrogen (H2) can be secured to 5 days or more.

[0135] Accordingly, in order to secure sufficient storage time of liquid hydrogen (H2), while also considering the slowdown in the increase in storage time of liquid hydrogen (H2) due to an increase in the volume ratio of liquid nitrogen (N2) to liquid hydrogen (H2), the volume of liquid nitrogen (N2) filled in the liquid nitrogen storage space (301) may be 0.001 to 1 times the volume of liquid hydrogen (H2) filled in the hydrogen storage space (101).

[0136] Referring to (b) of Fig. 10, when the volumes of liquid nitrogen (N2) and liquid hydrogen (H2) are the same, it can be confirmed that as the volume of liquid hydrogen (H2) increases, the storage time of liquid hydrogen (H2) increases, and the increase in the storage time of liquid hydrogen (H2) due to the increase in the volume of liquid hydrogen (H2) gradually slows down.

[0137] Accordingly, since the storage capacity of liquid hydrogen (H2) required for hydrogen vehicles, which are the target use of the hydrogen storage container (10), is typically 50 L or more, considering that the storage time of liquid hydrogen (H2) increases as the volume of liquid hydrogen (H2) charged increases, it is preferable that the volume of liquid hydrogen (H2) charged into the hydrogen storage space (101) is 50 L or more, preferably 40 L or more, and more preferably 30 L or more.

[0138] In addition, referring to the change in storage time of liquid nitrogen (N2) and liquid hydrogen (H2) according to the increase in volume of liquid nitrogen (N2) and liquid hydrogen (H2) shown as a blue solid line, it can be confirmed that when the volume of liquid nitrogen (N2) and liquid hydrogen (H2) is 5 L, a storage time of about 12 days of liquid hydrogen (H2) can be secured, and when the volume of liquid nitrogen (N2) and liquid hydrogen (H2) is 12 L, a storage time of about 18 days can be secured.

[0139] Considering the change in storage time of liquid hydrogen (H2) according to the increase in volume of liquid nitrogen (N2) and liquid hydrogen (H2), the volume of liquid hydrogen (H2) filled in the hydrogen storage space (101) may be 300 L or less, preferably 400 L or less, and more preferably 500 L or less. However, the volume of liquid hydrogen (H2) stored in the hydrogen storage space (101) is only an example and is not limited thereto.

[0140] Accordingly, in order to secure sufficient storage time of liquid hydrogen (H2), while taking into account the slowdown in the increase in storage time of liquid hydrogen (H2) due to an increase in the volume of liquid nitrogen (N2) and liquid hydrogen (H2), the volume of liquid hydrogen (N2) filled in the hydrogen storage space (101) may be 50 L to 300 L.

[0141] In addition, when miniaturizing the hydrogen storage container (10), the volume of liquid hydrogen (H2) filled in the hydrogen storage space (101) may be 5 L or more to secure a liquid hydrogen (H2) storage time of 12 days or more.

[0142] The increase in the storage time of liquid nitrogen (N2) and liquid hydrogen (H2) due to the increase in the volume of the above-mentioned liquid nitrogen (N2) and liquid hydrogen (H2) is due to the natural boil-off rate (BOR) of liquid nitrogen (N2) BOR LN2 and natural vaporization rate BOR of liquid hydrogen (H2) LH2 This can be confirmed by the following mathematical expressions 8 and 9. At this time, the following mathematical expressions 8 and 9 assume that there is no heat transfer by convection in an ideal vacuum in a steady state.

[0143] [Equation 8]

[0144]

[0145] [Equation 9]

[0146]

[0147] Here V LN2 is the volume of liquid nitrogen (N2), ρ LN2 is the density of liquid nitrogen (N2), H v,LN2 refers to the latent heat of liquid nitrogen (N2), and V LH2 is the volume of liquid hydrogen (H2), ρ LH2 is the density of liquid hydrogen (H2), H v,LH2 refers to the latent heat of liquefied hydrogen (H2).

[0148] Therefore, it can be confirmed that the natural vaporization rate of liquid nitrogen (N2) and liquid hydrogen (H2) decreases as the volume of liquid nitrogen (N2) and liquid hydrogen (H2) increases.

[0149] Fig. 11 is a drawing showing a method of manufacturing a hydrogen storage container (10) according to one embodiment of the present invention.

[0150] Referring to Fig. 11, the hydrogen storage container (10) may include a first storage container (700), a second storage container (800), and a coupling cover (900). In addition, the hydrogen storage container (10) may be manufactured in such a manner that the second storage container (800), which has been manufactured in advance, is inserted into the first storage container (700), and then the coupling cover (900) is coupled.

[0151] The second storage container (800) may include the innermost shell (100) and the inner shell (200).

[0152] The above first storage container (700) may include the outer shell (300) and the outermost shell (400).

[0153] The above combination cover (900) can be combined with the first storage container (700).

[0154] By this configuration, the hydrogen storage container (10) is manufactured by manufacturing two different storage containers each including two shells, rather than manufacturing a storage container including four shells at a time, thereby facilitating inspection and reducing losses when a defect occurs.

[0155] Additionally, the first storage container (700) and the second storage container (800) may be formed in a cylindrical shape with an open top.

[0156] At this time, the method of inserting the pre-fabricated second storage container (800) into the pre-fabricated first storage container (700) may be a method of inserting the second storage container (800) through the upper part of the opened first storage container (700), or a method of cutting the first storage container (700) in the longitudinal or radial direction, inserting the second storage container (800), and then welding the cut surface.

[0157] In addition, the method of manufacturing the hydrogen storage container (10) may further include a process of inserting the second storage container (800) into the first storage container (700), and then pressing the upper portions of the first storage container (700) and the second storage container (800) so that the upper diameter is formed smaller than the lower diameter based on a point spaced apart from the bottom surfaces of the first storage container (700) and the second storage container (800) in the vertical direction.

[0158] In addition, the coupling cover (900) can be coupled to the first storage container (700) to block the open upper portions of the first storage container (700) and the second storage container (800) when the second storage container (800) is inserted into the first storage container (700).

[0159] Through this configuration, heat transfer and leakage of liquefied hydrogen (H2) through the open upper portions of the first storage container (700) and the second storage container (800) can be prevented.

[0160] As described above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited thereto, and various modifications and variations are possible by a person having ordinary skill in the art to which the present invention pertains within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below.

[0161] [Explanation of symbols]

[0162] 10: Hydrogen storage tank

[0163] 100: Innermost Shell

[0164] 101: Hydrogen Storage Space

[0165] 110: Inside the Innermost Shell

[0166] 120: The exterior of the innermost shell

[0167] 121: First insulation

[0168] 122: First spacer

[0169] 200: Inner Shell

[0170] 201: The First Vacuum Space

[0171] 300: Outer Shell

[0172] 301: Liquid nitrogen storage space

[0173] 310: Inner surface of outer shell

[0174] 320: Outer shell exterior

[0175] 321: Second insulation

[0176] 322: Second spacer

[0177] 400: Outermost Shell

[0178] 401: Second vacuum space

[0179] 500: Hydrogen charging nozzle

[0180] 600: Nitrogen filling nozzle

[0181] 700: First storage container

[0182] 800: Second storage container

[0183] 900: Combination cover

[0184] H2: Liquid hydrogen

[0185] N2: Liquid nitrogen

Claims

1. Innermost shell forming hydrogen storage space; An inner shell surrounding the inner most shell to form a first vacuum space between the inner most shell and the outer surface of the inner most shell; An outer shell surrounding the inner shell to form a liquid nitrogen storage space between the outer surface of the inner shell; and An outermost shell that surrounds the outer shell to form a second vacuum space between the outer surface of the outer shell, Hydrogen storage tank.

2. In paragraph 1, The outer surface of the innermost shell is A first insulating material laminated along the outer surface of the innermost shell; and Comprising a plurality of first spacers arranged inside the first insulation material in a direction parallel to the lamination direction of the first insulation material, Hydrogen storage tank.

3. In paragraph 2, The outer surface of the above outer shell is A second insulating material laminated along the outer surface of the outer shell; and Including a plurality of second spacers arranged inside the second insulation material in a direction parallel to the lamination direction of the second insulation material. Hydrogen storage tank.

4. In paragraph 3, The inner surface of the innermost shell, the inner shell, the inner surface of the outer shell, and the outermost shell are formed of aluminum alloy, high density polyethylene (HDPE), polyamide, titanium, stainless steel, carbon fiber reinforced plastic (CFRP), or glass fiber reinforced plastic (GFRP). Hydrogen storage tank.

5. In paragraph 3, The above first insulation material and the above second insulation material are formed by laminating a plurality of aluminum foils, The first spacer and the second spacer are formed of fiber glass or polyurethane foam material. Hydrogen storage tank.

6. In paragraph 1, Liquid hydrogen is filled into the hydrogen storage space so that the temperature of the hydrogen storage space is maintained below the vaporization point of liquid hydrogen, Liquid nitrogen is filled into the liquid nitrogen storage space so that the temperature of the liquid nitrogen storage space is maintained below the vaporization point of the liquid nitrogen. Hydrogen storage tank.

7. In paragraph 6, The liquefied hydrogen charged into the above hydrogen storage space is: Filled at a temperature below the vaporization point of the above liquefied hydrogen, Hydrogen storage tank.

8. In paragraph 7, The liquefied hydrogen charged into the above hydrogen storage space is: It is charged at a temperature in the range of 1K to 10K lower than the vaporization point of the above liquefied hydrogen. Hydrogen storage tank.

9. In paragraph 6, The volume of liquid nitrogen filled in the above liquid nitrogen storage space is 0.001 to 1 times the volume of liquefied hydrogen to be filled in the above hydrogen storage space, Hydrogen storage tank.

10. In paragraph 6, The volume of liquefied hydrogen charged into the above hydrogen storage space is 50L or more, Hydrogen storage tank.

11. In paragraph 1, The above hydrogen storage container, A second storage container including the innermost shell and the inner shell; A first storage container including the outer shell and the outermost shell; and Including a coupling cover coupled to the first storage container, It is manufactured in such a way that the second storage container manufactured in advance is inserted into the first storage container manufactured in advance, and then the combination cover is combined. Hydrogen storage tank.

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