Case system and method for operating a case system

Abstract

The invention relates to a tank system (100) for storing cryogenic fluid. A tank system (100) comprises a tank (101), a heating element (103), where the tank (101) comprises an inner tank (105) and an outer tank (107), where the inner tank (105) encloses a storage volume (109) for storing a fluid, where the outer tank (107) encloses the inner tank (105), where the inner tank (105) is spaced from the outer tank (107) by an intermediate volume (111), where the heating element (103) is arranged between the inner tank (105) and the outer tank (107). The heating element (103) comprises a plurality of active thermal elements (113) arranged on the outer box (107), a plurality of passive thermal elements (115) arranged on the inner box (105), and a control unit configured for supplying an electrical current to the plurality of active thermal elements (113) in order to heat the plurality of passive thermal elements (115).

Description

Technical Field

[0001] The invention relates to a tank system and a method for operating a tank system. Background Art

[0002] For storing cryogenic liquids, such as hydrogen, two-part tanks are known, in which an inner tank is separated from an outer tank by an intermediate volume in which a vacuum exists.

[0003] The above-described design causes so-called “boiling off” of the tank, ie, a deformation of the tank, when the fluid stored in the tank is heated, for example, by a heating element in the tank.

[0004] However, it is necessary to heat the fluid in the tank as needed in order to keep the pressure in the tank constant by evaporation of the fluid when the fluid is withdrawn from the tank. Summary of the invention

[0005] Within the scope of the present invention, a tank system and a method for operating a tank system are proposed. Features and details relating to the method according to the invention are of course also applicable to the tank system according to the invention, and vice versa, so that the disclosures concerning the various aspects of the invention can always be mutually referenced.

[0006] The invention is particularly intended to provide the possibility of a robust tank system for storing cryogenic liquids.

[0007] Therefore, according to a first aspect of the present invention, a tank system for storing a cryogenic fluid is proposed.

[0008] The tank system of the present invention comprises a tank and a heating element, wherein the tank comprises an inner tank and an outer tank, wherein the inner tank surrounds a storage volume for storing a fluid, and the outer tank surrounds the inner tank, wherein the inner tank is separated from the outer tank by an intermediate volume, wherein the heating element comprises a plurality of active thermal elements arranged on the outer tank, a plurality of passive thermal elements arranged on the inner tank, and a control unit, and wherein the control unit is configured to supply current to the plurality of active thermal elements so as to heat the plurality of passive thermal elements.

[0009] In the context of the present invention, a cryogenic fluid is understood to be in particular a fluid which has been cooled below its normal boiling point, for example -253°C.

[0010] In the context of the present invention, a control unit is understood to be a computing unit which is configured, for example, for regulating or controlling the supply of electric current to the plurality of active thermal elements.

[0011] The invention is based on the principle that an active thermal element that can be controlled or energized by electric current is arranged on a first side or outer side of the intermediate volume, and a passive thermal element that can be heated by the active thermal element is arranged on a second side or inner side of the intermediate volume. The active thermal element and the passive thermal element are not coupled directly, in particular not mechanically, but are coupled, for example, inductively, so that energy for heating the passive thermal element can be transferred from the active thermal element to the passive thermal element via a vacuum that may be present in the intermediate volume, without having to provide an interface that penetrates the intermediate volume.

[0012] The fluid stored in the storage volume of the tank can be heated by the respective heatable passive thermal element, so that the fluid evaporates and generates pressure in the tank.

[0013] For example, the inner box may be constructed of stainless steel or aluminum.

[0014] For example, the outer box may be constructed from a fabric such as carbon fiber.

[0015] It can be arranged that each active thermal element is an electromagnet and each passive thermal element comprises a magnetic material.

[0016] By means of active thermal elements in the form of electromagnets and magnetic passive thermal elements, energy can be transferred from the active thermal elements to the passive thermal elements by magnetic induction, in particular so-called "back induction" or corresponding magnetic fields. In this case, the magnetic field between the active thermal element and the passive thermal element penetrates the intermediate volume, even if the intermediate volume is subjected to a vacuum.

[0017] In particular, eddy currents can be induced in the corresponding passive thermal element by the active thermal element configured as an electromagnet, so that the passive thermal element heats up due to the eddy current losses. The passive thermal element heated in this way transfers thermal energy to the fluid stored in the tank. For this purpose, the passive thermal element can be, for example, an expanding electrical conductor and a time-varying magnetic field can be generated by means of the active thermal element.

[0018] For example, the passive thermal element may be a spatially structured assembly of coils, metal blocks and / or metal sheets.

[0019] It can also be provided that a plurality of passive thermal elements are arranged on a surface of the inner box which is oriented toward the storage volume of the box.

[0020] The passive thermal elements arranged on the surface of the inner box oriented toward the storage volume of the box can, for example, be in direct contact with the fluid stored in the box and heat it accordingly well. To this end, the passive thermal elements can be welded, glued to the surface of the inner box or connected to the inner box by any other technically suitable method.

[0021] It can also be provided that the passive thermal elements are arranged in corresponding thin regions of the inner box, the wall thickness of the inner box being reduced in these thin regions relative to other regions of the inner box.

[0022] The thin area provides a receptacle for the passive thermal element, into which the passive thermal element can be at least partially introduced, so that the storage volume displaced by the passive thermal element is minimized and the storage volume of the tank is correspondingly maximized. In the event of local stress peaks due to the notch effect, the outer tank can be locally reinforced there.

[0023] It can also be provided that the inner box has a plurality of deformation regions in which the inner box extends further into the intermediate volume than in other regions of the inner box, and that the passive thermal elements are arranged in corresponding deformation regions of the inner box.

[0024] On the one hand, the storage volume displaced by the passive thermal element is minimized by the deformation region, and the storage volume of the tank is correspondingly maximized. On the other hand, the intermediate volume is locally thinned or the volume of the intermediate volume is reduced by the deformation of the corresponding deformation region into the intermediate volume, and the energy transfer between the corresponding active thermal element and the corresponding passive thermal element is maximized.

[0025] It may also be provided that an intermediate element is arranged between each active thermal element and each passive thermal element, wherein the intermediate element is configured for maximizing the heating of the corresponding passive thermal element.

[0026] On the one hand, the intermediate element, for example a metal block made of a soft magnetic material, in particular an iron ring, causes the intermediate volume between the corresponding active thermal element and the corresponding passive thermal element to be minimized. On the other hand, the intermediate element causes an optimized magnetic flux due to its magnetic properties. Therefore, the intermediate element acts as a kind of magnetic amplifier. For this purpose, the intermediate element can be configured, for example, to bunch the magnetic field lines emitted from the active thermal element and transfer them to the passive thermal element or focus them on the passive thermal element.

[0027] Alternatively or additionally, the inner box can be made of steel, in particular 316L steel, which, due to its molybdenum alloy, exhibits only minimal interaction with magnetic fields, whereby the magnetic flux between the active and passive thermal elements can be maximized or optimized.

[0028] It can also be provided that the inner box comprises a first layer and a second layer, wherein in the region between the passive thermal elements and the active thermal elements the inner box forms a receiving portion in which the first layer is spaced apart from the second layer, wherein the intermediate element is arranged in the receiving portion.

[0029] The intermediate elements arranged between the layers of the inner box enable the passive thermal elements to be arranged opposite the corresponding active thermal elements on the surface of the inner box. In this case, the first layer of the inner box, in which the passive thermal elements are arranged, can extend flat, and the second layer can extend into the intermediate volume in order to form a receptacle for the intermediate element, so that the intermediate volume is locally thinned in the region of the active and passive thermal elements, thereby optimizing or maximizing the magnetic flux between the active and passive thermal elements.

[0030] It can also be provided that the passive thermal elements are encapsulated by a cover, wherein the cover extends from a surface of the inner box in the direction of the storage volume of the box.

[0031] In particular, a cover that is directly thermally coupled to each passive thermal element can maximize the surface for transferring thermal energy through the passive thermal element into the corresponding fluid. To this end, the cover can, for example, have flow elements, such as fins, in particular a so-called "pin-fin structure".

[0032] It can also be provided that a plurality of active thermal elements are arranged in the intermediate volume on the side of the outer box facing the inner box.

[0033] By arranging the active thermal elements in the intermediate volume, the distance between the respective passive thermal elements and the active thermal elements is minimized and the magnetic flux between the heating elements is maximized or optimized.

[0034] It may also be provided that the control unit is configured to supply current to the plurality of active thermal elements as a function of the pressure acting in the tank.

[0035] The pressure in the tank can be controlled or regulated by supplying a plurality of active thermal elements with current as a function of the pressure acting in the tank. For this purpose, the pressure can be measured, for example, by means of a pressure sensor or can be mathematically modeled, for example, as a function of the temperature in the tank and / or the state of a fuel consumer, such as a fuel cell system, which is supplied with fuel via the tank.

[0036] According to a second aspect, the invention relates to a method for operating a possible configuration of the proposed tank system.

[0037] The proposed method includes ascertaining the pressure in the tank, ascertaining the pressure difference between the ascertained pressure and a predefined target pressure, and heating a plurality of passive thermal elements until the pressure difference falls below a predefined control threshold value.

[0038] In particular, the pressure in the corresponding tank can be kept constant or quasi-stable using the proposed method.

[0039] The advantages of the tank system for storing cryogenic fluids described in detail according to the first aspect of the invention are equally applicable to the method of operating the possible configuration of the tank system proposed according to the second aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Further advantages, features and details of the invention are apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the accompanying drawings. The features mentioned in the claims and the description may be essential to the invention individually or in any combination.

[0041] The following schematically shows:

[0042] Figure 1 : Overview of a possible configuration of the proposed box system,

[0043] Figure 2 : Schematic diagram of the first configuration of the proposed box system,

[0044] Figure 3 : Schematic diagram of the second configuration of the proposed box system,

[0045] Figure 4 : Schematic diagram of the third configuration of the proposed box system,

[0046] Figure 5 : Schematic diagram of the fourth configuration of the proposed box system, and

[0047] Figure 6 : Possible configurations of the proposed method. DETAILED DESCRIPTION

[0048] exist Figure 1 A detailed view of a tank system 100 for storing a cryogenic fluid, presently hydrogen, is shown in FIG.

[0049] The tank system 100 includes a tank 101 and a heating element 103 .

[0050] The tank 101 comprises an inner tank 105 and an outer tank 107 , wherein the inner tank 105 surrounds a storage volume 109 for storing a fluid, and the outer tank 107 surrounds the inner tank 105 .

[0051] The inner box 105 is separated from the outer box 107 by an intermediate volume 111. In the intermediate volume 111 there is a vacuum.

[0052] The heating element 103 includes an active thermal element 113 arranged on the outer box 107 and a passive thermal element 115 arranged on the inner box 105, and a control unit not shown.

[0053] The control unit is configured to supply current to the active thermal element 113 in order to thereby heat the passive thermal element 115. To this end, the control unit may, for example, induce a time-varying magnetic field in the active thermal element 113, so that the passive thermal element 115 heats up due to eddy current losses, transfers thermal energy to the fluid and generates pressure in the tank 101.

[0054] For example, the active thermal element 113 is an electromagnet that generates a magnetic field when supplied with current. By supplying current in a time-varying manner, in particular with a changing polarity, a magnetic field can be generated by the active thermal element 113, which induces eddy currents in the passive thermal element 115, so that the passive thermal element 115 is heated due to eddy current losses.

[0055] The heated passive thermal element 115 causes the liquid stored in the tank 101 to evaporate, thereby causing the pressure in the storage volume 109 to increase.

[0056] exist Figure 2 , the structure of the tank system 100 is shown, wherein the inner tank 105 is shown in two layers with a first layer 117 , for example a pressure body, in particular made of steel, and a second layer 119 , for example a radiation shield, which forms a receptacle 121 for an intermediate element 123 .

[0057] The intermediate element 123 is made of a ferromagnetic material and the intermediate volume 111 is thinned locally so that the magnetic flux between the active thermal element 113 and the passive thermal element 115 is optimized or maximized, thereby minimizing the energy required for building up pressure in the tank 101 .

[0058] exist Figure 3 , the structure of the tank system 100 is shown, wherein the inner tank 105 is completely deformed and locally forms a deformation region 125 , in which the inner tank 105 thins the intermediate volume 111 and provides a volume for arranging a passive thermal element 115 .

[0059] Alternatively, the intermediate element 123 may be arranged on the inner box 105 in direct contact with the passive thermal element 115 .

[0060] exist Figure 4 , the structure of the tank system 100 is shown in FIG. 1 , wherein the passive thermal element 115 is encapsulated by the cover 129 .

[0061] The cover 129 forms the receiving portion 131 and is in direct thermal contact in particular with the passive thermal element 115 and maximizes the surface through which thermal energy is introduced into the storage volume 109 or into the fluid.

[0062] exist Figure 5 1 shows the structure of a tank system 100, wherein the inner tank 105 is locally thinned in the thinned region 127, so that the thinned region provides a volume into which the passive thermal element 115 is partially immersed. Thus, the portion of the storage volume 109 that is displaced by the passive thermal element 115 is minimized.

[0063] exist Figure 6 The following table shows the method for running Figure 1A method 200 of the box system 100 is provided.

[0064] Method 200 comprises a first ascertainment step 201 in which the pressure in tank 101 is ascertained, a second ascertainment step 203 in which a pressure difference between the ascertained pressure and a predefined target pressure is ascertained, and a heating step 205 in which the passive thermal element 115 is heated until the pressure difference falls below a predefined control threshold.

Claims

1. A tank system (100) for storing cryogenic fluids, in, The box system (100) comprises: - box (101), - a heating element (103), The box (101) includes an inner box (105) and an outer box (107). wherein the inner box (105) surrounds a storage volume (109) for storing a fluid, and the outer box (107) surrounds the inner box (105), wherein the inner box (105) and the outer box (107) are separated by an intermediate volume (111), The heating element (103) comprises a plurality of active thermal elements (113) arranged on the outer box (107), a plurality of passive thermal elements (115) arranged on the inner box (105), and a control unit. The control unit is configured to supply current to the plurality of active thermal elements (113) so as to heat the plurality of passive thermal elements (115).

2. The box system (100) according to claim 1, It is characterized in that Each active thermal element (113) is an electromagnet, and each passive thermal element (115) includes a magnetic material.

3. The box system (100) according to claim 1 or 2, It is characterized in that A plurality of passive thermal elements (115) are arranged on a surface of the inner box (105) oriented toward the storage volume (109) of the box (101).

4. The tank system (100) according to any one of the preceding claims, It is characterized in that Each passive thermal element (115) is arranged in a corresponding thin region (127) of the inner box (105), and the wall thickness of the inner box (105) is reduced in the thin region relative to other regions of the inner box (105).

5. The tank system (100) according to any one of the preceding claims, It is characterized in that The inner box (105) has a plurality of deformation regions (125), in which the inner box (105) extends further into the intermediate volume (111) than in other regions of the inner box (105), and each passive heat generating element (115) is arranged in a corresponding deformation region (125) of the inner box (105).

6. The tank system (100) according to any one of the preceding claims, It is characterized in that An intermediate element (123) is arranged between each active heat generating element (113) and each passive heat generating element (115), Wherein, the intermediate element (123) is configured to maximize the heating of the corresponding passive thermal element (115).

7. The box system (100) according to claim 6, It is characterized in that The inner box (105) includes a first layer (117) and a second layer (119), wherein, in the region between each passive thermal element (115) and each active thermal element (113), the inner box (105) forms a receiving portion in which the first layer (117) is spaced apart from the second layer (119), Therein, the intermediate element (123) is arranged in the receiving portion.

8. The tank system (100) according to any one of the preceding claims, It is characterized in that Each passive thermal element (115) is encapsulated by a cover (129). The cover (129) extends from the surface of the inner box (105) toward the storage volume (109) of the box (101).

9. The tank system (100) according to any one of the preceding claims, It is characterized in that A vacuum exists in the intermediate volume (111).

10. The tank system (100) according to any one of the preceding claims, It is characterized in that A plurality of active thermal elements (113) are arranged in the intermediate volume (111) on a side of the outer box (107) facing the inner box (105).

11. Tank system (100) according to any one of the preceding claims, It is characterized in that The control unit is configured to supply electric current to a plurality of active thermal elements (113) depending on the pressure acting in the tank (101).

12. A method (200) for operating a tank system (100) according to any one of claims 1 to 11, in, The method (200) comprises: - determining (201) the pressure in the box (101), - determining (203) the pressure difference between the determined pressure and a predetermined target pressure, - heating (205) a plurality of passive thermal elements (115) until the pressure difference falls below a predefined control threshold value.

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