ENERGY RECOVERY ASSEMBLY, FUEL CELL SYSTEM AND VEHICLE WITH ENERGY RECOVERY ASSEMBLY

Abstract

An energy recovery assembly, fuel cell system and vehicle, with an electrolyzer configured to provide a fuel and an oxidant, a fuel cell configured to convert the fuel and an oxidant to electrical energy, a tank configured to store the fuel or the oxidant, and a conduction pathway connecting the tank to the electrolyzer and the fuel cell. The assembly also includes: an expansion machine disposed in the conduction pathway and configured to expand a fluid flowing through the expansion machine and to obtain mechanical energy; and a valve arrangement configured to put the pathway in a first mode in which the fuel or the oxidant is guided to the tank, or in a second mode in which the fuel cell or the oxidant is guided to the fuel cell, wherein the fuel or the oxidant in the first and second modes flows through the expansion machine.

Claims

1. An energy recovery assembly comprising: an electrolyzes configured to provide a fuel and an oxidant; a fuel cell configured to convert the fuel and the oxidant to electrical energy; a tank configured to store the fuel or the oxidant; a conduction pathway connecting the tank to the electrolyzer and the fuel cell, an expansion machine disposed in the conduction pathway and configured to expand a fluid flowing through the expansion machine and to obtain mechanical energy; and a valve arrangement configured to put the conduction pathway in a first conduction mode in which the fuel or the oxidant is guided to the tank, or in a second conduction mode in which the fuel cell or the oxidant is guided to the fuel cell, wherein the fuel or the oxidant in the first conduction mode and the second conduction mode flows through the expansion machine.

2. The energy recovery assembly as claimed in claim 1, wherein the valve arrangement comprises a multiway valve configured to connect a tank conduit of the tank either to an outlet conduit of the expansion machine or to a feed to the expansion machine.

3. The energy recovery assembly as claimed in claim 1, wherein the valve arrangement comprises a shutoff valve disposed in an outlet conduit of the electrolyzer and configured to adjust a flow cross section of the outlet conduit or a shutoff valve disposed in a feed to the fuel cell and configured to adjust a flow cross section of the feed.

4. The energy recovery assembly as claimed in claim 1, wherein the valve arrangement comprises a multiway valve connecting a feed of the expansion machine either to an outlet conduit of the electrolyzer or to a tank conduit of the tank.

5. The energy recovery assembly as claimed in claim 4, wherein the valve arrangement comprises a further multiway valve set up to connect an outlet conduit of the expansion machine either to a feed to the fuel cell or to a tank conduit of the tank.

6. The energy recovery assembly as claimed in claim 1, wherein the expansion machine is a rotary flow machine.

7. The energy recovery assembly as claimed in claim 6, wherein the rotary flow machine comprises a tooth arrangement having preferably seven teeth.

8. The energy recovery assembly as claimed in claim 7, wherein the tooth arrangement comprises a first section and a second section, wherein the first section disposed rotatably on a fixed conduit arrangement of the expansion machine and the second section is disposed rotatably about the first section, and wherein an expansion space of the expansion machine is provided between the first section and the second section.

9. The energy recovery assembly as claimed in claim 1, wherein the expansion machine further comprises a transmission output configured to output the mechanical energy obtained as rotary movement, or wherein the expansion machine is configured to convert the mechanical energy to electrical energy and output the electrical energy, or both.

10. The energy recovery assembly as claimed in claim 9, further comprising: a generator or motor coupled to the expansion machine.

11. The energy recovery assembly as claimed in claim 9, wherein the electrolyzer is configured to be operated under a pressure between 15 and 200 bar.

12. A regenerative fuel cell system comprising: the energy recovery assembly as claimed in claim 1; and a water tank configured to collect and store water formed in the fuel cell.

13. A vehicle comprising: at least one energy recovery assembly as claimed in claim 1.

14. The energy recovery assembly as claimed in claim 6, wherein the expansion machine is a rotary piston expansion machine.

15. The energy recovery assembly as claimed in claim 7, wherein the rotary flow machine comprises seven teeth.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Preferred working examples of the invention are elucidated in detail with reference to the schematic drawings appended, wherein:

[0032] FIG. 1 shows a schematic of an energy recovery assembly and reflects a first conduction mode;

[0033] FIG. 2 shows a schematic of an energy recovery assembly and reflects a second conduction mode;

[0034] FIG. 3 shows a schematic of a variant of a valve arrangement of an energy recovery assembly;

[0035] FIG. 4A shows a schematic of a longitudinal section of an expansion machine,

[0036] FIG. 4B shows a schematic of a cross section of an expansion machine; and

[0037] FIG. 5 shows a schematic of a vehicle with an energy recovery assembly.

DETAILED DESCRIPTION OF EMBODIMENTS

[0038] FIG. 1 shows a schematic of an energy recovery assembly 1. This comprises an electrolyzer 10 and a fuel cell 20, wherein the electrolyzer 10, by means of electrical energy, is able to generate and provide a fuel and an oxidant, while the fuel cell 20 can convert the fuel and an oxidant to electrical energy. The energy recovery assembly 1 further comprises a tank 30 in which fuel or oxidant can be stored, and a conduction pathway provided between tank 30, electrolyzer 10 and fuel cell 20. The conduction pathway can fluidically couple and/or connect the tank 30, electrolyzer 10 and fuel cell 20 to one another.

[0039] Part of the conduction pathway may be an outlet conduit 11 provided at an outlet of the electrolyzer 10, which leads off the fuel or oxidant generated in the electrolyzer 10. The electrolyzer 10 may of course comprise a second outlet (not shown separately), at which the other electrolysis product (oxidant or fuel) can flow out and be led off

[0040] A shutoff valve 12 may be provided for adjustment of a flow cross section of the outlet conduit 11. The shutoff valve 12 can completely close or completely open the flow cross section of the outlet conduit 11, or set it in any intermediate position. In this way, it is possible to control the pressure in the outlet conduit 11 of the electrolyzer 10 and hence (as far as and/or) at the outlet of the electrolyzer.

[0041] The energy recovery assembly 1 may also comprise an expansion machine 100. The outlet conduit 11 from the electrolyzer 10 may be fluidically coupled here to a feed 111 to the expansion machine 100. As shown in FIG. 1, fuel or oxidant is conducted from the electrolyzer 10 via the outlet conduit 11 (with the shutoff valve 12 open) and the conduit 111 into the expansion machine 100. The fuel or the oxidant, after leaving the expansion machine 100, is conducted onward via an outlet conduit 112 of the expansion machine 100 into a tank conduit 43 of the tank 30. The fuel or the oxidant can subsequently be stored in the tank 30.

[0042] On account of a pressure differential between the electrolyzer 10 and the tank 30, it is possible to expand the fuel or the oxidant in the expansion machine 100, meaning that the pressure of the fuel or the oxidant can be reduced, in which case the energy released is obtained in the form of mechanical energy by means of the expansion machine 100. Although the pressure differential decreases as the tank 30 is increasingly filled, the energy released can nevertheless be converted to mechanical energy in the course of expansion. The fuel or the oxidant may be in liquid form or gaseous form. It is likewise conceivable that the fuel or the oxidant is converted from the liquid state to the gaseous state in the expansion machine 100.

[0043] The expansion machine 100 may be coupled to a generator or motor 101. The generator 101 can convert the mechanical energy which is obtained in the expansion machine 100 to electrical energy. The coupling between expansion machine 100 and generator 101 may be via a transmission outlet 140. For example, the transmission outlet 140 may be a common shaft and/or a transmission (not shown separately). It is likewise conceivable that the expansion machine 100 has an integrated generator, such that electrical energy can be tapped directly from the expansion machine 100. This electrical energy can be used for the operation of the motor 101.

[0044] The energy recovery assembly 1 shown in FIG. 1 may also comprise a consumer 35 of the fuel or the oxidant, which is fluidically connected via an appropriate connection conduit 37 and shutoff valve 36 to the tank conduit 43. The consumer 35 may also be a further tank. It is likewise possible to design the valve 36 as a safety valve, such that any excess pressure in the conduction pathway can be released automatically. The consumer 35 in that case, rather than a tank, may also reflect the environment into which fluid is discharged from the conduction pathway for safety reasons.

[0045] FIG. 2 shows a schematic of an energy recovery assembly 1 that reflects a second conduction mode. In the second conduction mode, the fuel or the oxidant can be conducted from the tank 30 to the fuel cell 20. FIGS. 1 and 2 show conduits through which the fuel or the oxidant can flow (i.e. are not closed by a (shutoff) valve) by solid lines, whereas dotted lines indicate closed, inactive conduits.

[0046] For example, shutoff valve 12 and shutoff valve 36 are closed in the second conduction mode according to FIG. 2. This allows the pressurized fluid (gas and/or liquid), the fuel or the oxidant here, to flow out of the tank 30 via the tank conduit 43 to the multiway valve 40. The multiway valve 40 then closes a section 41 of the tank conduit 43 connected to the outlet conduit 112 of the expansion machine 100. Instead, the multiway valve 40 establishes a fluidic connection between the tank conduit 43 and an intermediate conduit 42 which is fluidically connected to the feed 111 to the expansion machine 100. After flowing through the expansion machine 100 and the outlet conduit 112, the fuel or the oxidant is run through the shutoff valve 22, which is now open, into a feed 21 to the fuel cell 20. The section 41 of the tank conduit 43, as described, is closed by the multiway valve 40.

[0047] In this conduction mode too, there is a pressure differential between the tank 30 and the fuel cell 20. Therefore, the fuel or the oxidant does not just automatically flow to the fuel cell 20; instead, it is also possible to expand the fuel or the oxidant in the expansion machine 100 and to convert energy released to mechanical and/or electrical energy. The expansion machine 100 may be designed or may be adjustable in such a way that there is a pressure in the outlet conduit 112 that always corresponds to the operating pressure of the fuel cell 20, irrespective of the exit pressure that exists in the tank 30. Alternatively or additionally, the operating pressure of the fuel cell 20 may also be controlled/adjusted via the valve 22.

[0048] The other elements shown in FIG. 2 correspond to those that have already been elucidated with regard to FIG. 1. Therefore, these components are not described again.

[0049] FIG. 3 shows a schematic of a variant of a valve arrangement of an energy recovery assembly 1. FIG. 3 shows merely a section of the energy recovery assembly 1, with the other portion of the energy recovery assembly 1 corresponding to the energy recovery assembly from FIG. 1 or 2. Rather than the shutoff valve 12 in the outlet conduit 11 of the electrolyzer 10 and the multiway valve 40, in the variant according to FIG. 3, a multiway valve 61 is provided directly between outlet conduit 11, feed 111 to the expansion machine 100 and tank conduit 43. In a first conduction mode, the multiway valve 61 connects the outlet conduit 11 to the feed 111, as shown by the upper arrow. In a second conduction mode, the multiway valve 61 connects the tank conduit 43 to the feed 111, as shown by the lower arrow.

[0050] In addition, in the valve arrangement according to FIG. 3, the shutoff valve 22 in the feed 21 to the fuel cell 20 is replaced by a further multiway valve 62. As likewise indicated by arrows, in a first conduction mode, the outlet conduit 112 from the expansion machine 100 is fluidically connected to a section 41 of the tank conduit 43 (lower arrow), and, in a second conduction mode, the outlet conduit 112 is fluidically connected to the feed 21 to the fuel cell 20 (upper arrow). Thus, in the first and second conduction modes, the conduction pathway generated by the corresponding valve settings is achieved in a corresponding manner to those from FIGS. 1 and 2.

[0051] Irrespective of the respective variants of the valve arrangement, the valves 12, 22, 40, 61, 62 may be implemented in a valve block or a valve unit. It is thus possible to shorten conduit lengths between the respective valves or to dispense with these conduits entirely. In a likewise very compact implementation, such a valve block or valve unit may also be connected to or integrated into the expansion machine 100 for construction purposes. Such an expansion machine 100 accordingly requires only three connections for connection of the outlet conduit 11 of the electrolyzer 10, the feed 21 to the fuel cell 20, and the tank conduit 43.

[0052] Merely by way of example, the energy recovery assembly 1 may be present in a regenerative fuel cell system 2 (see FIG. 1) which additionally comprises a water tank 25. The water tank 25 can collect and store water formed in the fuel cell 20. The fuel cell system 2 in fuel cell operation can therefore generate electrical energy from the fuel stored, for example, in tank 30. If another source of electrical energy is available, the electrolyzer 10 may be operated while the fuel cell 20 is switched off. Then the electrolyzer 10 can split the water stored in the water tank 25 at least into fuel by means of electrical energy. It is thus possible to convert excess electrical energy to fuel, which is stored in tank 30 until the other source of electrical energy is no longer available and the system is switched back to fuel cell operation. In each of the two modes of operation, however, it is possible to use the expansion machine 100, and hence very efficiently to continuously and additionally provide mechanical and/or electrical energy.

[0053] FIGS. 4A and 4B shows a schematic of a longitudinal section and a transverse section of an expansion machine 100. The expansion machine 100 shown in FIGS. 4A and 4B is a rotary piston expansion machine. It is of course also possible to use a different type of expansion machine 100 in the systems described here. The rotary piston expansion machine 100 may comprise, for example, a fixed conduit arrangement 110 containing the feed 111 on one side and the outlet conduit 112 from the expansion machine 100 on the other side.

[0054] The rotary piston expansion machine 100 may comprise a tooth arrangement. The tooth arrangement shown merely by way of example in FIGS. 4A and 4B comprises a first section 120 disposed in a rotatable manner on the fixed conduction arrangement 110, and a second section 130 disposed rotatably about the first section 120. For example, the first section 120 or the second section 130 may be disposed in a rotatable manner on the conduit arrangement 110 by means of bearings 151.

[0055] If fuel or oxidant then flows via the feed 111 to the first section 120 of the tooth arrangement, the fuel or the oxidant can pass through corresponding openings or apertures in the first section 120 into an expansion space 131. As a result of the expansion (reduction in pressure) of the fuel or oxidant, and by virtue of the different number of teeth in the first section and hollows or recesses in the second section 130, the first section 120 is pushed away from the second section 130. On account of the mounting of the first section 120 and of the second section 130 and owing to their mobility relative to one another, the first section 120 is rotated about the conduit arrangement 110, as a result of which the second section 130 is also rotated.

[0056] In this case, in another (roughly opposite) region of the expansion machine 100, the expansion space 131 is reduced in size as a result of convergence of the first and second sections 120, 130. Thus, the fuel or the oxidant is pushed through a corresponding opening or aperture in the first section 120 into the outlet conduit 112. Ultimately, the fuel or the oxidant is expanded, and the energy released is converted to the rotation of the first and second sections 120, 130, and hence mechanical energy.

[0057] The expansion machine 100 may comprise a housing 150. The housing 150 may be in fixed form, in which case the first and second sections 120, 130 rotate within the housing. Alternatively, the housing 150 may also be connected to the second section 130, such that the housing 150 rotates together with the second section 130.

[0058] A fixed housing 150 offers the option of using the relative movement between housing 150 and second section 130 for the formation of a generator. For instance, magnets (not shown), for example permanent magnets, may be disposed in the second section 130, in which case the housing 150 comprises coils (not shown) for generation of electrical current by the moving magnets.

[0059] Alternatively or additionally, the expansion machine 100 may also comprise a transmission outlet 140. This may exist merely by way of example in the form of an opening in the housing 150 and a gear disposed therein (not shown separately), which rotates together with the first section 120 or the second section 130.

[0060] FIG. 5 shows a schematic of a vehicle 5 with an energy recovery assembly 1. The vehicle 5 may, as shown in FIG. 5, be an aircraft that uses the energy recovery assembly 1 for generation of electrical power. It is likewise conceivable that the vehicle 5 may be a different mode of mass transport, for example a train, ship or bus, or even a car.

[0061] The vehicle 5 may also be a spaceship, satellite or pseudo-satellite (e.g. High Altitude Pseudo Satellite—HAPS). In this case, in particular, regenerative fuel cell systems 2 are advantageous since filling of a fuel cell system is not possible. Two different modes of operation are usually needed in the case of such space vehicles 5 as well. Firstly, solar cells (not shown) can convert sunlight to electrical energy. If, however, the solar cells are in the shade, the electrical energy has to be obtained by means of a different source (storage means), for example a fuel cell. It is thus possible, during the generation of electrical energy by means of the solar cells, to use a portion of the electrical energy in an electrolyzer 10 for generation of a fuel. While the solar cells are in the shade, the fuel thus generated can be converted to electrical energy in a fuel cell 20. With the energy recovery assembly 1 described here, it is possible in both modes of operation to generate additional mechanical energy and/or electrical energy by means of the expansion machine 100.

[0062] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.