INTERCONNECTING DEVICE FOR SOLID OXIDE FUEL CELLS AND A FUEL CELL STACK COMPRISING THE SAME

Abstract

An interconnecting device for compact solid oxide fuel cells includes a body having first and second interface surfaces on distinct body sides. The first interface surface includes spaced apart anode and cathode exhaust inputs. The second interface surface includes spaced apart fuel and air supply ports. The anode exhaust input fluidly communicates with the fuel supply port and/or anode exhaust outlet arranged at a distance to the first and second interface surfaces. The cathode exhaust input fluidly communicates with the air supply port and/or cathode exhaust outlet arranged at a distance to the first and second interface surfaces. The first electrical port is arranged at or in the cathode exhaust input and is connectable from the first interface surface. The second electrical port is arranged at or in the fuel supply port and is connectable from the second interface surface, and is electrically connected to the second electrical port.

Claims

1. An interconnecting device for compact solid oxide fuel cells, the interconnecting device comprising a body having a first interface surface, and a second interface surface on distinct sides of the body, wherein the first interface surface comprises at least one anode exhaust input and at least one cathode exhaust input in a distance to the at least one anode exhaust input, wherein the second interface surface comprises at least one fuel supply port and at least one oxidant supply port in a distance to the at least one fuel supply port, wherein the at least one anode exhaust input is in fluid communication with at least one of the at least one fuel supply port or at least one anode exhaust outlet arranged at a distance to the first interface surface and the second interface surface, wherein the at least one cathode exhaust input is in fluid communication with the at least one of the at least one oxidant supply port or at least one cathode exhaust outlet arranged at a distance to the first interface surface and the second interface surface, wherein at least one first electrical port is arranged at or in the at least one cathode exhaust input and is connectable from the first interface surface, wherein at least one second electrical port is arranged at or in the at least one fuel supply port and is connectable from the second interface surface, and wherein the at least one first electrical port is electrically connected to the at least one second electrical port.

2. The interconnecting device of claim 1, wherein the first interface surface and the second interface surface are arranged on opposed sides of the body.

3. The interconnecting device of claim 1, further comprising at least one fuel inlet arranged on a side of the body that does neither comprise the first interface surface nor the second interface surface, wherein the at least one fuel inlet is in fluid communication with the at least one fuel supply port.

4. The interconnecting device of claim 1, further comprising at least one oxidant inlet arranged on a side of the body that does neither comprise the first interface surface nor the second interface surface, wherein the at least one oxidant inlet is in fluid communication with the at least one oxidant supply port.

5. The interconnecting device of claim 4, wherein the at least one oxidant supply port is in fluid communication with both the at least one oxidant inlet and the at least one cathode exhaust input.

6. The interconnecting device of claim 5, wherein an oxidant passage between the at least one cathode exhaust input and the at least one oxidant inlet comprises an orifice, wherein the body comprises the at least one cathode exhaust outlet, and wherein the orifice is dimensioned to divide a fluid flow from the at least one cathode exhaust input to the at least one oxidant supply port and the cathode exhaust outlet in a predetermined fraction for a predetermined operating state of the respective fuel cells attached to the interconnecting device.

7. The interconnecting device of claim 1, wherein the first interface surface comprises at least one pair of anode exhaust input and cathode exhaust input, and wherein the second interface surface comprises at least one pair of fuel supply port and oxidant supply port.

8. The interconnecting device of claim 1, wherein the at least one cathode exhaust input and the at least one oxidant supply port comprise an opening, which has a rectangular, round or otherwise regular shape.

9. The interconnecting device of claim 8, wherein the first electrical port and the second electrical port surround the respective opening of the at least one cathode exhaust input and at least one oxidant supply port at least in the respective interface surface.

10. The interconnecting device of claim 1, wherein the body has a cuboid shape having a width, height, and depth, wherein the first interface surface and the second interface surface are opposed in a depth-wise direction, and wherein the width and height of the body exceeds the depth of the body.

11. The interconnecting device of claim 1, wherein the body is made from a ceramic or metallic material.

12. A fuel cell stack, comprising a plurality of solid oxide fuel cells and at least one interconnecting device according to claim 1 arranged between two consecutive solid oxide fuel cells.

13. The fuel cell stack of claim 12, wherein the fuel cells comprise at least one column with at least one pair of an anode channel and a cathode channel arranged in an alternating manner in a block.

14. A vehicle, comprising at least one fuel cell stack of claim 12.

15. The vehicle of claim 14, wherein the vehicle is an aircraft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In the following, the attached drawings are used to illustrate exemplary embodiments in more detail. The illustrations are schematic and not to scale. Identical reference numerals refer to identical or similar elements.

[0034] FIG. 1 shows a fuel cell stack with SOFCs and an interconnecting device in a first example in an exploded view.

[0035] FIG. 2 shows an interconnecting device in a second example in perspective and cross sectional views.

[0036] FIG. 3 shows an interconnecting device in a third example in perspective and cross sectional views.

[0037] FIG. 4 shows an interconnecting device in a fourth example in perspective and cross sectional views.

[0038] FIG. 5 shows an aircraft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] FIG. 1 shows a fuel cell stack 2 in an exploded view. Here, two solid oxide fuel cells 4 (SOFC) are shown, which together enclose an interconnecting device 6. The fuel cell 4 comprises a fuel cell block 8, which exemplarily is of a cuboid shape. It comprises two anode channels 10 and two cathode channels 12, which extend through the fuel cell block 8 in a straight, linear manner Exemplarily, the two anode channels 10 are arranged side by side in a top portion of the fuel cell block 8 and the two cathode channels 12 are arranged side by side underneath the two anode channels 10 in a bottom portion of the fuel cell block 8. The anode channels 10 comprise a circumferential coating, which constitute anodes. In analogy, the cathode channels 12 comprise a cathode coating, which constitute the respective cathodes. The fuel cell block 8 may be made from a ceramic material and fuel cells are created by pairwise combinations of anode channels 10 and cathode channels 12.

[0040] The interconnecting device 6 serves to connect the fuel cells 4 to form the fuel cell stack 2 similarly to a bipolar plate. Due to the different concept of the SOFC 4 compared to conventional, two-dimensional, planar PEM fuel cells or the like, the interconnecting device 6 has a different design. It comprises a body 14 having a first interface surface 16 and a second interface surface 18. The first interface surface 16 is designed to flushly contact the fuel cell 4 on the left-hand side in FIG. 1, while the second interface surface 18 is designed to flushly contact the fuel cell 4 on the right-hand side of FIG. 1.

[0041] The first interface surface 16 comprises two anode exhaust inputs 20 arranged side by side, while the positions of the anode exhaust inputs 20 match the positions of the two anode channels 10 of the fuel cell 4. The anode exhaust inputs 20 receive exhaust gas from the anode channels 10, i.e., surplus hydrogen and water vapor.

[0042] Underneath, two cathode exhaust inputs 22 are provided, wherein their positions match the positions of the two cathode channels 12. The cathode exhaust inputs 22 receive cathode exhaust, i.e., surplus oxidant, which may be oxygen or oxygen depleted air.

[0043] In this exemplary embodiment, anode exhaust gas entering the anode exhaust inputs 20 is routed to an anode exhaust outlet 24, which is located at a first side 26 of the interconnecting device 6. This means, that surplus fuel, i.e., hydrogen, exits the interconnecting device 6 through the anode exhaust outlet 24. The first side 26 extends perpendicularly to both the first interface surface 16 and the second interface surface 18. In FIG. 1, it is arranged on the left-hand side. Consequently, the total flow of surplus fuel that enters the interconnecting device 6 leaves the interconnecting device 6 and is not routed into the subsequent fuel cell 4.

[0044] Cathode exhaust, which enters the cathode exhaust inlets 22, is routed to a cathode exhaust outlet 28, which is arranged at a second side 30 of the interconnecting device 6. The second side 30 extends perpendicularly to both the first interface surface 16 and the second interface surface 18 and is arranged at a bottom portion of the interconnecting device 6 in FIG. 1. Consequently, the whole flow of surplus oxidant, e.g., oxygen depleted air, leaves the interconnecting device 6.

[0045] An oxidant inlet 32 is provided at a third side 34, which extends perpendicularly to the first interface surface 16 and the second interface surface 18 and is located on the right-hand side of the interconnecting device 6. Here, oxidant, e.g., air, enters the interconnecting device 6 and flows to oxidant supply ports 36 arranged on the first interface surface 18. Hence, the subsequent fuel cell 4, which is arranged downstream of the interconnecting device 6, is supplied with oxidant through the oxidant inlet 32 only.

[0046] On the fourth side 38, fuel inlets 40 are provided, through which fuel flows to fuel supply ports 42 arranged on the second interface surface 18 to enter the anode channels 10 of the subsequent fuel cell 4. Consequently, the interconnecting devices 6 in this secondary embodiment is able to completely separate exhaust flows from the first fuel-cell 4 and the second fuel-cell 4, wherein peripheral devices may be connected with the interconnecting device 6 to further handle these exhaust and supply flows. In this example, the fourth side 38 perpendicularly extends between the first interface surface 16 and the second interface surface 18 and is located at a top portion of the interconnecting device 6. The exhaust outlets 24 and 28 are thus clearly separated from the inlets 36 and 40.

[0047] For electrically connecting the fuel cells 4, the interconnecting device 6 comprises first electrical ports 44 on the first interface surface 16 and second electrical ports 46 on the second interface surface 18. The first electrical ports 44 are provided by a material section that surround the anode exhaust inlets 20, while the second electrical ports 46 surround the fuel supply ports 42. Thus, they will electrically contact the respective anode channels 10 and cathode channels 12 of two subsequent fuel cells 4 when the interconnecting device 6 is sandwiched between the respective fuel cells 4. Electrons travel through the interconnecting device 6 through an electrical conductor 47, which is integrated into the interconnecting device 6 and extends from the first electrical ports 44 and second electrical ports 46. On the first interface surface 16, the anode exhaust inlets 20 may comprise an insulating layer or a recess 48 to avoid an electrical contact between the anode channels 10 and the interconnecting device 6.

[0048] The interconnecting device 6 may be created by a three-dimensional printing process, i.e., an additive manufacturing method, wherein the whole interconnecting device 6 may be made from a light-weight, electrically insulating material, which is able to withstand the elevated temperatures that are created in the fuel cell process. For example, it may be Yttria Stabilized Zirconia, which is also usable as electrolyte for the SOFCs 4.

[0049] In other variants, which are not explicitly shown as examples, the interconnecting device 6 may be made from an electrically conductive material. Then, a separate conductor 47 would not be required, but instead isolating means for preventing short circuits between the respective parts of the fuel cells 4.

[0050] In FIG. 2, another example of an interconnecting device 50 is provided and is shown in perspective and cross sectional views. Here, the design is generally equal to the interconnecting device 6, but comprises an oxidant passage 52 between the cathode exhaust inlets 22 and the oxidant supply ports 36, such that at least a part of cathode exhaust gas may flow into the oxidant supply ports 36 to be re-used. For example, air as an oxidant may be only partially oxygen depleted and has an oxygen content that is still usable in a further fuel cell 4. The oxidant passage 52 may comprise an orifice 54, i.e., constricted space between the cathode exhaust inlet 22 and the oxidant supply port 36, which orifice 54 is dimensioned to divide a fluid flow from the cathode exhaust inputs 22 to the at least one oxidant supply port 36 and the cathode exhaust outlets 28 in a predetermined fraction for a predetermined operating state of the respective fuel cells 4 attached to the interconnecting device 50.

[0051] In FIG. 3, and interconnecting device 56 is shown in perspective and cross sectional views, in which cathode exhaust gas and anode exhaust gas simply flow through the interconnecting device 56 from one fuel cell 4 to a subsequent fuel cell 4. Anode exhaust inlets 20 are thus in a direct fluid communication with fuel supply ports 42 and cathode exhaust inlets 22 are in direct fluid communication with oxidant supply ports 36. If air is used as oxidant, depleted air from an upstream SOFC 4 has only a marginal effect, and the fuel gas can be adjusted by pressure to be sufficient for several downstream SOFCs 4. This design has several considerable advantages. For instance, due to the simple through-flow of both reactants, the interconnecting device 56 may be made with a simpler design. It may be dimensioned to be thinner and thus more weight-saving. It is also possible to easily benefit from relatively short dimensions of each SOFC 4 and short current collection distances.

[0052] In FIG. 4, another exemplary embodiment of an interconnecting device 58 is shown in perspective and cross sectional views, which is adapted to conform a different design of a solid oxide fuel cell 60 and which is mainly based on the design shown in FIG. 3. However, the SOFCs 60 show electrochemical reactions in both transverse directions of the SOFCs 60 and the interconnecting device is correspondingly modified.

[0053] FIG. 5 shows an aircraft 62, into which a fuel cell stack having a plurality of fuel cells 4 or 60 and interconnecting devices 6, 56 or 58 is arranged.

[0054] 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.

REFERENCE NUMERALS

[0055] 2 fuel cell stack [0056] 4 fuel cell [0057] 6 interconnecting device [0058] 8 fuel cell block [0059] 10 anode channel [0060] 12 cathode channel [0061] 14 body [0062] 16 first interface surface [0063] 18 second interface surface [0064] 20 anode exhaust input [0065] 22 cathode exhaust input [0066] 24 anode exhaust outlet [0067] 26 first side [0068] 28 cathode exhaust outlet [0069] 30 second side [0070] 32 oxidant inlet [0071] 34 third side [0072] 36 oxidant supply port [0073] 38 fourth side [0074] 40 fuel inlet [0075] 42 fuel supply port [0076] 44 first electrical port [0077] 46 second electrical port [0078] 47 conductor [0079] 48 layer/recess [0080] 50 interconnecting device [0081] 52 oxidant passage [0082] 54 orifice [0083] 56 interconnecting device [0084] 58 interconnecting device [0085] 60 fuel cell [0086] 62 aircraft