Fluid cryogenic agent tank device and fuel cell system

Abstract

The invention relates to a fluid cryogen tank arrangement for a fuel cell system, the fluid cryogen tank arrangement comprising an inner pressure vessel for containing a pressurized fluid cryogen; an outer pressure vessel surrounding the inner pressure vessel wherein the inner pressure vessel and the outer pressure vessel are separated from each other by an intermediate space; and a thermally insulating spacer device arranged within the intermediate space and configured to support the inner pressure vessel and the outer pressure vessel against each other. The invention also relates to a fuel cell system.

Description

Technical Field

[0001] The present invention relates to a fluid cryogenic agent tank device for a fuel cell system, and a fuel cell system with the fluid cryogenic agent tank device. Background Art

[0002] In a fuel cell system (FCS), oxygen, an oxidant from the ambient air, is usually used to react with hydrogen in the fuel cell to form water or water vapor, thereby providing electricity through electrochemical conversion. The required hydrogen is stored in special tanks at high pressure and low temperature.

[0003] For example, document EP 1 707 867 A1 describes a long-term cryogenic storage system with a storage tank shell, wherein the storage tank shell comprises a protective outer layer, an impermeable inner layer and at least one insulating intermediate layer between the outer layer and the inner layer. In addition, the cryogenic storage system also comprises a nanoporous material filling the storage tank shell inside the inner layer of the storage tank shell, wherein the nanoporous material provides a storage medium for the cryogenic agent.

[0004] However, when the inner layer is fixed inside the outer layer, if a solid connection with a certain cross-sectional area is used, a so-called boil-off phenomenon may occur due to the high heat conduction. Summary of the invention

[0005] The present invention provides a fluid cryogen tank arrangement for a fuel cell system and a fuel cell system having the features of the independent claims.

[0006] According to a first aspect, the present invention relates to a fluid cryogen tank device for a fuel cell system. The fluid cryogen tank device comprises an inner pressure vessel for accommodating a pressurized fluid cryogen and an outer pressure vessel surrounding the inner pressure vessel. The inner pressure vessel and the outer pressure vessel are separated from each other by an intermediate space. In addition, the fluid cryogen tank device further comprises an insulating spacing device, which is arranged in the intermediate space and is configured to support the inner pressure vessel and the outer pressure vessel to each other.

[0007] According to a second aspect, the present invention relates to a fuel cell system with a fluid cryogen tank arrangement according to the present invention and a supply / discharge device fluidically connected to the fluid cryogen tank arrangement.

[0008] The invention is based on the idea of ​​fixing the second storage element or the inner pressure vessel in the interior of the first storage element or the outer pressure vessel and in doing so simultaneously reducing the heat transfer from the first storage element into the second storage element.

[0009] Advantageously, the spacer can fix the inner pressure vessel or the inner tank relative to the outer pressure vessel so that the two pressure vessels cannot move relative to each other. In addition, the spacer can also thermally insulate the outer pressure vessel from the inner pressure vessel. This means that the spacer reduces heat transfer, in particular heat conduction and convection.

[0010] Advantageous embodiments and refinements emerge from the further dependent claims and from the description, with reference to the drawings.

[0011] According to the expansion scheme of the fluid cryogen tank device, the spacer device has a plurality of hollow spacer elements. In this way, the heat conduction performance of the spacer device and the weight of a plurality of spacer elements or the spacer device can be reduced.

[0012] According to a further development of the fluid cryogen tank arrangement, a plurality of spacer elements are spherically configured. The spherical configuration or convex shape of the spacer elements can reduce heat conduction by minimizing the stop area or contact area.

[0013] According to an extended solution of the fluid cryogenic tank device, a plurality of spacer elements are arranged in a hexagonal, i.e., regular hexagonal spherical layer, so that each spherical spacer element is surrounded by six spherical spacer elements to form a most compact spherical packing with a layer sequence ABAB. Thus, as much air as possible can be exhausted from the intermediate space. In addition, the cost required to generate a vacuum in the intermediate space can be reduced.

[0014] According to an embodiment of the invention, the diameter of the plurality of spacer elements is dimensioned such that the intermediate space is filled by the plurality of spacer elements by at least 65%, in particular by at least 70%. As a result, as much air as possible can be removed from the intermediate space. Furthermore, the costs for generating a vacuum in the intermediate space can be reduced. Furthermore, the macroscopic expansion (i.e. the diameter) can also simplify handling.

[0015] According to an extension of the fluid cryogen tank device, the contact surface between the spacer and the inner pressure vessel or the outer pressure vessel is configured substantially in a punctiform manner. Alternatively, the contact surface between the spacer and the inner pressure vessel and the outer pressure vessel is configured substantially in a punctiform manner. In this way, the effective area of ​​heat conduction between the inner pressure vessel and the outer pressure vessel can be reduced.

[0016] According to a further development of the fluid cryogen tank arrangement, the remaining volume of the intermediate space not filled by the spacer arrangement contains a vacuum. Since the spacer element provides a defined distance or gap, a vacuum can be reliably established.

[0017] In the framework of the present invention, vacuum may refer to the state of a fluid in a volume or space when the pressure is significantly lower than the ambient pressure or atmospheric pressure under normal conditions.

[0018] According to an extended solution of the fluid cryogen tank device, the inner pressure vessel has a first wall layer and a second wall layer, wherein the second wall layer is arranged on the outer surface of the first wall layer. Here, the first wall layer comprises an inner contact surface in contact with the cryogen. The second wall layer comprises a fiber reinforced plastic. In particular, the second wall layer may comprise a carbon fiber reinforced plastic. Preferably, the inner wall layer may be made of a metal (e.g., aluminum) or a plastic (e.g., polyamide or polyethylene). In particular, the inner wall layer may be configured as a liner.

[0019] The cryogen is, for example, cryogenic hydrogen.

[0020] According to another development of the fluid cryogen tank arrangement, the inner pressure vessel further comprises a third wall layer arranged on an outer surface of the second wall layer, wherein the third wall layer comprises a thermal radiation shielding device for protecting the cryogen from thermal radiation.

[0021] In other words, the structure of the inner pressure vessel can be described as follows: The inner tank or inner pressure vessel consists of a pressure body coated on the inside (also called liner), a thermal radiation shield or third wall layer and a carbon fiber fabric surrounding the pressure body.

[0022] Preferably, the spacer can be made of plastic or other materials with poor thermal conductivity.

[0023] For example, a supply / exhaust arrangement of a fuel cell system may be fluidly connected to a closable inlet / outlet of a fluid cryogen tank arrangement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be explained below with reference to the accompanying drawings. In the drawings:

[0025] Figure 1 a schematic view of a cross section of a fluid cryogen tank assembly according to an embodiment of the present invention;

[0026] Figure 2A According to another embodiment of the present invention Figure 1 A schematic detailed view of a fluid cryogenic tank arrangement;

[0027] Figure 2B According to another embodiment of the present invention Figure 1 A schematic detailed view of a fluid cryogenic tank arrangement;

[0028] Figure 3 a schematic view in cross section of a spacing element according to another embodiment of the invention; and

[0029] Figure 4 A fuel cell system according to another embodiment of the present invention.

[0030] In all figures, identical or functionally identical elements and devices are marked with the same reference numerals. The numbering of the method steps is for the sake of clarity and does not generally imply a specific chronological order. In particular, multiple method steps can be performed simultaneously. DETAILED DESCRIPTION

[0031] Further advantages, features and details of the present invention will be presented in the following description, in which various embodiments are described in detail with reference to the drawings.

[0032] Figure 1 A schematic view in cross section of a fluid cryogen tank arrangement 1 is shown. The fluid cryogen tank arrangement 1 is provided, for example, for use in a fuel cell system.

[0033] The fluid cryogen tank arrangement 1 comprises an inner pressure vessel 2 for containing pressurized fluid cryogen 9a; 9b. The cryogen may be in liquid (9a) and gaseous (9b) state. The cryogen is preferably hydrogen and may, for example, supply a fuel cell system.

[0034] For example, the inner pressure vessel 2 comprises a first wall layer 6, a second wall layer 7 and a third wall layer 8, wherein in particular the third wall layer 8 is optional and can therefore also be omitted (see Figure 2A ). The second wall layer 7 is arranged on the outer surface of the first wall layer 6. The first wall layer 6 can be configured as an inner lining and comprises an inner contact surface in contact with the cryogenic agent 9a; 9b. In addition, the second wall layer 7 comprises carbon fiber reinforced plastic or carbon fiber fabric.

[0035] The optional third wall layer 8 is exemplarily arranged on the outer surface of the second wall layer 7, wherein the third wall layer 8 comprises a thermal radiation shielding device for protecting the cryogen from thermal radiation.

[0036] In addition, the fluid cryogenic tank device 1 further comprises an outer pressure vessel 3, which surrounds the inner pressure vessel 2. The inner pressure vessel 2 and the outer pressure vessel 3 are separated from each other by an intermediate space 4. The intermediate space 4 is sealed by the outer surface of the inner pressure vessel 2 and the inner surface of the outer pressure vessel 3. Here, the outer surface of the inner pressure vessel 2 corresponds to the outer surface of the third wall layer 8.

[0037] In addition, the fluid cryogen tank arrangement 1 comprises a thermally insulating spacer 5. The spacer 5 is arranged in the intermediate space 4 and is configured to support the inner pressure vessel 2 and the outer pressure vessel 3 against each other. This means that the inner pressure vessel 2 and the outer pressure vessel 3 cannot be displaced relative to each other.

[0038] In the present embodiment, the spacer 5 has a plurality of hollow and spherical spacer elements 5a. The diameters of the plurality of spacer elements are dimensioned such that the intermediate space 4 is filled by the plurality of spacer elements 5a by at least 65%, in particular by at least 70%. The remaining volume of the intermediate space 4 not filled by the spacer 5 or the plurality of spacer elements 5a is a vacuum. For example, the remaining volume comprises at most 35%, preferably at most 30% of the intermediate space 4. The remaining volume is generated in particular by the gaps between the individual spacer elements 5a. For example, the vacuum can be generated by a vacuum pump.

[0039] Figure 2A Shows Figure 1 Detailed schematic view of a fluid cryogenic tank device 1. Here, the inner pressure vessel 2 comprises only a first wall layer 6 and a second wall layer 7. Therefore, the outer surface of the inner pressure vessel 2 corresponds to the outer surface of the second wall layer 7.

[0040] The intermediate space 4 contains a plurality of spacer elements 5a, which form the spacer device 5. The contact surfaces between the spacer device 5 and the inner pressure vessel 2 and the outer pressure vessel 3 are substantially punctiform. A plurality of hollow and spherical spacer elements 5a are substantially in contact with each other in a punctiform manner. Furthermore, depending on the position at which the spacer elements 5a are positioned in the intermediate space 4, each spacer element 5a has a substantially punctiform contact surface with the inner pressure vessel 2 or the outer pressure vessel 3.

[0041] Figure 2B yes Figure 1 A schematic detailed view of a fluid cryogenic tank arrangement 1 in FIG. Figure 2A The difference of the fluid cryogenic tank device 1 shown in FIG. 1 is that the inner pressure vessel 2 has a third wall layer 8. Therefore, the outer surface of the inner pressure vessel 2 corresponds to the outer surface of the third wall layer 8.

[0042] Figure 3 A schematic view in cross section of a spacing element 5a is shown. Figure 3 As shown, the spacer element 5A has a diameter d and a wall thickness t. The wall thickness t is dimensioned in such a way that the spacer element 5a can withstand the mechanical and thermal loads in the intermediate space 4 without breaking or bursting.

[0043] Figure 4 A fuel cell system 10 is shown. The fuel cell system 10 includes a Figure 1 , 2AOr the fluid cryogen tank device 1 of 2B. In addition, the fuel cell system 10 has a supply / discharge device fluidically connected to the fluid cryogen tank device 1. In particular, the fuel cell system 10 can be fluidically connected to a closable inlet / outlet of the fluid cryogen tank device 1, wherein the closable inlet / outlet is arranged on the outer pressure vessel 3.

[0044] Although the present invention has been explained above by way of example by means of embodiments, it is not limited thereto but can be modified in various ways. In particular, combinations of the above-described embodiments are also conceivable.

Claims

1. A fluid cryogen tank device (1) for a fuel cell system, comprising: An inner pressure vessel (2) for containing a pressurized fluid cryogen (9a; 9b); An outer pressure container (3), the outer pressure container surrounding the inner pressure container (2), wherein: The inner pressure container and the outer pressure container (2, 3) are separated from each other by an intermediate space (4); and A thermally insulating spacer (5) is arranged in the intermediate space (4) and is designed to support the inner pressure container (2) and the outer pressure container (3) against each other.

2. The fluid cryogenic tank device (1) according to claim 1, wherein: The spacer device (5) has a plurality of hollow spacer elements (5a).

3. The fluid cryogenic tank device (1) according to claim 2, wherein: The plurality of spacer elements (5a) are each configured in a spherical shape.

4. The fluid cryogenic tank arrangement (1) according to claim 3, wherein: The plurality of spacer elements (5a) are arranged in hexagonal (regular hexagonal) spherical layers, so that each spherical spacer element (5a) is surrounded by six spherical spacer elements (5a), forming a most compact spherical packing with a layer sequence of ABAB.

5. The fluid cryogenic tank device (1) according to claim 3 or 4, wherein: The diameter of the plurality of spacer elements is dimensioned such that the intermediate space (4) is filled by the plurality of spacer elements (5a) by at least 65%, in particular by at least 70%.

6. A fluid cryogenic tank arrangement (1) according to any one of the preceding claims, wherein: The contact surface between the spacer (5) and the inner pressure container and / or the outer pressure container (2, 3) is designed essentially in a punctiform manner.

7. A fluid cryogenic tank arrangement (1) according to any one of the preceding claims, wherein: The remaining volume of the intermediate space (4) not filled by the spacer device (5) contains a vacuum.

8. A fluid cryogenic tank arrangement (1) according to any one of the preceding claims, wherein: The inner pressure vessel (2) comprises a first wall layer (6) and a second wall layer (7), wherein the second wall layer is arranged on the outer surface of the first wall layer (6), wherein the first wall layer (6) comprises an inner contact surface for contacting a cryogenic agent (9a; 9b), and wherein the second wall layer (7) comprises fiber reinforced plastic.

9. The fluid cryogenic tank arrangement (1) according to claim 8, wherein: The inner pressure vessel (2) further comprises a third wall layer (8) arranged on the outer surface of the second wall layer (7), wherein the third wall layer (8) comprises a thermal radiation shielding device for protecting the cryogen (9a; 9b) from thermal radiation.

10. A fuel cell system (10) having a fluid cryogen tank arrangement (1) according to any one of the preceding claims and a supply / discharge device fluidically connected to the fluid cryogen tank arrangement (1).

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