WATERCRAFT AND METHOD FOR OPERATING A WATERCRAFT

Abstract

A watercraft includes at least one high-temperature superconducting coil and a cooling system for cooling the high-temperature superconducting coil to a cryogenic operating temperature, wherein the cooling system has a first cryostat tank, which surrounds the high-temperature superconducting coil and is designed to hold a liquid phase of a cryogenic coolant; wherein the watercraft also has a load, which is designed to convert an operating medium in the form of a fuel and/or in the form of a material promoting combustion; wherein at least one first material component of the operating medium is formed by the cryogenic coolant; and wherein the first cryostat tank is designed to hold a major part of the required total amount of the first material component of the operating medium for the operation of the load. A method operates a watercraft of this type.

Claims

1. A watercraft having comprising: at least one high-temperature superconducting coil, and a cooling system for cooling the high-temperature superconducting coil to a cryogenic operating temperature, wherein the cooling system has a first cryostat tank, which surrounds the high-temperature superconducting coil and is designed to hold a liquid phase of a cryogenic coolant, wherein the watercraft also has a load, which is designed to convert an operating medium in the form of a fuel and/or in the form of a combustion-promoting substance, wherein at least one first substance component of the operating medium is formed by the cryogenic coolant, and wherein the first cryostat tank is designed to hold a majority of the total quantity of the first substance component of the operating medium required for the operation of the load.

2. The watercraft as claimed in claim 1, wherein the first cryostat tank is designed to hold a proportion of at least 75%, of the total quantity of the first substance component of the operating medium required for operation of the load.

3. The watercraft as claimed in claim 1, wherein the cryogenic coolant is or comprises hydrogen, methane, natural gas or oxygen.

4. The watercraft as claimed in claim 1, wherein the operating medium has a fuel as the first substance component and a combustion-promoting substance as a second substance component, wherein the first cryostat tank is designed to hold the first substance component, and wherein the cooling system has a second cryostat tank, which encloses the first cryostat tank in the form of a jacket and is designed to hold the second substance component.

5. The watercraft as claimed in claim 1, wherein the load is designed to be operated with a gaseous phase of the cryogenic coolant.

6. The watercraft as claimed in claim 5, which comprises, as part of the cooling system, a gas outlet line, which is arranged at least partially within the first cryostat tank and is thermally coupled there, at least in a partial region, to a part of the superconducting coil in such a way that cooling of the superconducting coil is effected by the gaseous phase of the cryogenic coolant flowing in the gas outlet line.

7. The watercraft as claimed in claim 1, wherein the load is a fuel cell system.

8. The watercraft as claimed in claim 1, wherein the at least one high-temperature superconducting coil forms a component part of an electric machine which is designed to drive the watercraft.

9. The watercraft as claimed in claim 8, wherein the superconducting coil is designed as part of a stator winding of the electric machine.

10. The watercraft as claimed in claim 8, wherein the superconducting coil is designed as part of a rotor winding of the electric machine.

11. The watercraft as claimed in claim 1, wherein in which the at least one superconducting coil is designed to generate a magnetic flux outside the watercraft.

12. The watercraft as claimed in claim 1, wherein the watercraft is designed as an unmanned watercraft.

13. The watercraft as claimed in claim 12, wherein the watercraft is designed as a mine-clearing drone.

14. A method for operating a watercraft as claimed claim 1, comprising: cooling the at least one high-temperature superconducting coil via the liquid phase of the cryogenic coolant in the first cryostat tank, and using the same cryogenic coolant as the substance component of the operating medium which is converted by means of the load.

15. The method as claimed in claim 14, further comprising: operating the load with gaseous cryogenic coolant, which evaporates during cooling of the at least one superconducting coil.

16. The watercraft as claimed in claim 2, wherein the first cryostat tank is designed to hold a proportion of at least 90% of the total quantity of the first substance component of the operating medium required for the operation of the load.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The invention is described below by means of a number of preferred exemplary embodiments with reference to the appended drawings, in which:

[0031] FIG. 1 shows a schematic sectional illustration of a watercraft according to a first exemplary embodiment of the invention, and

[0032] FIGS. 2 to 4 show schematic sectional illustrations of various embodiments of superconducting coils and their associated cryostat tanks.

DETAILED DESCRIPTION OF INVENTION

[0033] In the figures, identical or functionally identical elements are provided with the same reference signs.

[0034] FIG. 1 shows a schematic partially perspective sectional illustration of a watercraft 1 according to a first example of the invention. In the example shown, this watercraft is a mine-clearing drone, which here just dips into the water W. Alternatively or additionally, however, use while floating on the surface of the water is also possible. The watercraft has a central longitudinal axis A and moves along a direction of travel which coincides with the longitudinal axis A, for example.

[0035] Here, the watercraft 1 is a self-propelled unmanned drone which can move in the water by means of an electric motor 2 and a propeller 3 mechanically coupled thereto and does not have to be towed by a mother ship. This drone is designed to generate a predetermined time-dependent magnetic profile at a specific target location in order to be able to detonate a magnetically triggerable sea mine. In order to generate the desired magnetic profile, the watercraft 1 is equipped with one or more superconducting magnet coils. Purely by way of example, several different superconducting magnet coils are shown for the watercraft 1: thus, the electric motor 2 has a stator winding 4 which can contain one or more superconducting coils. Moreover, the electric motor 2 has a rotor winding 7, which can likewise contain one or more superconducting coils. In addition, a single superconducting magnet coil 5 is shown in the rear part of the drone, said coil likewise cooperating in the generation of the desired magnetic profile but not being part of the electric motor. However, these windings or coils are illustrated only by way of example, and it is not necessary for all of them to be present at the same time in a watercraft. Thus, it is sufficient if at least one superconducting coil is present, this being embodied, for example, as part of the stator winding 4 or as part of the rotor winding 7 or else as a separate magnet coil 5. The other coils or windings can then optionally be configured alternatively as normally conducting coils.

[0036] The watercraft 1 has a load 6 which is designed for converting an operating medium. In FIG. 1, purely by way of example, this load is arranged in the front region of the watercraft. For example, the load 6 may be a fuel cell which provides the electrical energy required for the electric motor 2. Such a fuel cell can, in particular, be operated with an operating medium which comprises hydrogen and oxygen. In this case, the hydrogen acts as fuel and forms a first substance component of the operating medium of the load 6. The oxygen acts as a combustion-promoting substance and forms a second substance component of the operating medium. If the watercraft is to be used under the surface of the water, it is generally expedient if both the first substance component and the second substance component are stored and carried along in the watercraft. The storage tanks and supply lines used for this purpose are, however, not shown in FIG. 1 for the sake of clarity. According to the invention, however, at least the first substance component of the operating medium is formed by a cryogenic coolant which is used for cooling the superconducting coil to a cryogenic operating temperature. This dual use of the first substance component is explained in more detail in conjunction with FIGS. 2 to 4.

[0037] Thus, FIG. 2 shows a schematic sectional illustration of a superconducting coil 15 in its associated cryostat tank 10. This coil 15 can be used in a watercraft according to one example of the present invention, for example in a watercraft which is configured in a manner similar to that in FIG. 1. In principle, the coil may, in particular, be a coil of a rotor winding 7 or a coil of a stator winding 4 or a separate magnet coil 5. It should be assumed below, for example, that the coil 15 is a fixed coil in relation to the rest of the watercraftthat is to say a stator coil or a separate magnet coil 5.

[0038] The superconducting coil 15 is arranged within a first cryostat tank 10 and is surrounded by the latter. A liquid cryogenic coolant 11 is arranged in the interior of this first cryostat tank 10 and flows around the superconducting coil 15 and thus cools it to a cryogenic operating temperature. For example, the liquid cryogenic coolant is liquid hydrogen. During the cooling of the coil 15, this liquid hydrogen partially evaporates, with the result that a region containing gaseous coolant 12 is formed geodetically above a coolant level 17. This gaseous coolant 12 can escape from the first cryostat tank 10 through a gas outlet line 13 and can be fed via this line 13 to the load 6, which is shown here only schematically. Thus, in this way, the hydrogen required by a fuel cell, for example, is fed to it. In the example shown, this hydrogen is stored substantially within the first cryostat tank 10. Apart from the comparatively small volume of the line 13, there is, in particular, no additional storage reservoir for the hydrogen. This ensures that the space required within the cryostat tank for the liquid coolant can also be used at the same time for storing the operating medium of the load 6. This eliminates the space for an additional storage tank, at least for the first substance component of the operating medium. To refill the cryostat tank 10, the liquid coolant 11 can be introduced either through the line 13 or through a further line and/or opening (not illustrated specifically here).

[0039] In the example shown, the cryostat tank 10 is of double-walled design, with a vacuum space V being formed between the two walls. This serves to thermally insulate the interior of the cryostat from the comparatively warm external environment. Alternatively or additionally, however, the cryostat tank can also be thermally insulated by other measures, for example by means of perlite and/or superinsulation. In general, the cryostat tank can be of annular configuration (that is to say topologically biconnected), with the result that it surrounds an annular coil having two coil legs in a comparatively compact arrangement, the center of the coil then being free of coolant. Alternatively, however, the cryostat tank can also be configured as a simple pot (that is to say it can be topologically simply connected), with the result that the region in the interior of an annular coil can also be filled by the liquid cryogenic coolant. This simpler embodiment is shown in the sectional illustration of FIG. 2. In this case, the two superimposed coil elements 15a and 15b may be, for example, two opposite legs of the same coil 15. Alternatively, however, it would also be possible for the two elements 15a and 15b shown to be separate coils lying one above the other and for FIG. 2 to represent only a section of an annular cryostat tank 10.

[0040] If the quantity of cryogenic coolant required for the operation of the load 6 is stored substantially within the first cryostat tank 10 and is thus not refilled from an external storage tank, the coolant level 17 gradually drops during the operation of the watercraft 1. This is caused by the fact that the liquid coolant 11 is gradually evaporated and the gaseous coolant 12 which is formed is fed to the load 6. Correspondingly, FIG. 3 shows an operating state in which a significant portion of the liquid coolant 11 has already been consumed. Therefore, the coolant level 17 is already below half of the upper coil leg 15a, and therefore there is already no longer a flow of liquid coolant 11 around at least this coil leg 15a. In order nevertheless to achieve reliable cooling of the entire coil 15 to the cryogenic operating temperature, different measures can be taken. Thus, on the one hand, the coil 15 itself can be designed to be highly thermally conductive, thus ensuring that a flow of liquid coolant 11 around the lower coil leg 15b is sufficient to cool the upper coil leg 15a to a sufficiently low temperature by heat conduction. This can be achieved, for example, by a highly thermally conductive metallic substrate of a superconducting strip conductor on which the coil winding is based. Alternatively or additionally, however, the individual partial regions 15a and 15b can also be connected to one another in a heat-conducting manner by one or more additional bridging elements. For example, such an additional element can be provided by a heat-conducting coil carrier (not shown here).

[0041] As an alternative or additional measure for improved cooling of the upper coil part 15a, however, it is also possible for the gas outlet line 13 to be configured in such a way that efficient cooling of the coil part 15a is made possible by the gas flowing in said line. Such an optional configuration is shown by way of example in FIG. 3: here, the gas outlet line 13 is extended into the interior of the cryostat 10 and shaped in such a way that it is thermally coupled to the upper coil leg 15a at least in a partial region. This ensures that the gas flowing in the line 13 can cool this part 15a of the coil more efficiently than would be the case without such coupling. In particular, as a result of this particular embodiment, it is especially the outflowing gas which selectively absorbs the heat from the upper coil leg 15a, and excessive heating of the remaining gaseous coolant 12, which is above the coolant level 17 but is not yet being taken from the gas space, is advantageously reduced.

[0042] FIG. 4 shows a schematic sectional illustration of a coil 15 according to a further exemplary embodiment of the invention. The coil is arranged in a first cryostat tank 10 in a manner similar to the example of FIG. 2 and is cooled there by a liquid cryogenic coolant 11, which is converted in part by evaporation into gaseous coolant 12. In addition, the first cryostat tank 10 is here also surrounded by a second cryostat tank 20, which likewise contains a liquid coolant 21. These two cryostat tanks 10 and 20 are nested in one another in such a way that, overall, an onion-skin-like arrangement consisting of a plurality of enveloping jackets is obtained: the inner liquid coolant 11 flows around the coil 15. This coolant is enclosed by the double-walled first cryostat tank 10. The outer liquid coolant 21 flows around this inner cryostat tank. This outer coolant is enclosed by the double-walled cryostat tank 20. Overall, this onion-skin-like structure results in particularly effective thermal insulation of the internal superconducting coil 15.

[0043] As a particularly advantageous option, the selected liquid coolant 11 in the first cryostat tank 10 and the selected liquid coolant 21 in the second cryostat tank 20 can be different. In particular, the inner coolant 11 can be liquid hydrogen and the outer coolant 21 can be liquid oxygen. Or, in more general terms, the inner coolant can be a first substance component of the operating medium and the outer coolant can be a second substance component of the operating medium of the load 6. Accordingly, in the example of FIG. 4, these two coolants are fed in parallel to the load 6 after their evaporation through respectively associated gas outlet lines 13 and 23. It is thus possible, in particular, to implement the supply of hydrogen and oxygen to a fuel cell in a particularly simple and space-saving manner.

LIST OF REFERENCE SIGNS

[0044] 1 watercraft [0045] 2 electric motor [0046] 3 propeller [0047] 4 stator winding [0048] 5 magnet coil [0049] 6 load [0050] 7 rotor winding [0051] 10 first cryostat tank [0052] 11 liquid coolant [0053] 12 gaseous coolant [0054] 13 gas outlet line [0055] 13a partial region [0056] 15 superconducting coil [0057] 15a upper coil leg [0058] 15b lower coil leg [0059] 17 coolant level [0060] 20 second cryostat tank [0061] 21 liquid second substance component [0062] 22 gaseous second substance component [0063] 23 second gas outlet line [0064] A central axis [0065] V vacuum space [0066] W water