Fuel cell module and gas supply method for fuel cell module

Abstract

To provide a fuel battery module having a fuel battery stack structure in which fuel cells are stacked capable of making uniform the temperature within the fuel battery stack.SOLUTION: A fuel battery module in a preferred aspect of the present invention includes; a fuel battery stack constituted of multiple stacked fuel cells that supply fuel gas and oxidizer gas to generate electricity; and a temperature adjustment component that performs heat exchange between the supply gas, which is at least one of a fuel gas and an oxidizer gas, supplied to the fuel cell, and an exhaust gas, which is at least one of the fuel gas and the oxidizing gas, discharged from the fuel battery cell.SELECTED DRAWING: Figure 3A

Description

[[Technical Field]]

[0001] The present invention relates to a fuel cell module. [[Background Art]]

[0002] In recent years, fuel cells have attracted attention as clean energy sources that enable high energy conversion and do not emit pollutants such as carbon dioxide and nitrogen oxides. Among fuel cells, solid oxide fuel cells (hereinafter abbreviated as SOFC) have high power generation efficiency and can use easily handled gases such as hydrogen, methane, and carbon monoxide as fuel. Therefore, they have many advantages compared to other types of fuel cells, and are expected to serve as cogeneration systems excellent in energy saving and environmental performance.

[0003] An SOFC has a structure in which a solid electrolyte is sandwiched between a fuel electrode and an air electrode. With the electrolyte serving as a partition wall, a fuel gas such as hydrogen is supplied to the fuel electrode side, and an oxidant gas such as air or oxygen gas is supplied to the air electrode side. In particular, planar SOFCs are promising because high output can be obtained by stacking them.

[0004] The planar SOFC stack disclosed in Patent Document 1 has a structure in which fuel cell stacks are repeatedly arranged between a base plate and an end plate. The fuel cell stacks include active fuel cell stacks that generate power by supplying fuel gas and air, and inactive fuel cell stacks that do not generate power because no fuel gas is supplied and only air is supplied. The inactive fuel cell stacks are arranged between the base plate or the end plate and the active fuel cell stacks. [[Prior Art Literature]] [[Patent Literature]]

[0005] [[Patent Document 1]] Japanese National Publication of International Patent Application No. 2017-508254 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0006] Patent Document 1 focuses on the temperature difference between the center and ends of an active fuel cell stack that generates electricity, in order to improve efficiency by reducing power generation variations within the fuel cell stack in the operating environment of a flat-plate SOFC stack. A non-power-generating inert fuel cell stack is inserted as a dummy between the end of the active fuel cell stack and the base plate or end plate, which is a factor in the temperature drop due to gas introduction. This reduces the temperature difference between the center and ends of the active fuel cell stack, and the temperature variation is managed by the operating voltage difference, which is an indicator of power generation.

[0007] However, in Patent Document 1, the temperature distribution from the base plate to the end plate remains unchanged; only a dummy is replaced in the region where the temperature drop is large. As a result, under operating conditions, the temperature of the active central part of the fuel cell stack rises as power is generated, and the temperature difference with the base plate and end plate increases. Furthermore, as fuel cell cells generate more power, it becomes necessary to flow large amounts of fuel gas and oxidizer gas, which increases the temperature drop of the base plate and other parts where the gas is introduced, making temperature uniformity within the fuel cell stack an increasingly difficult issue.

[0008] Therefore, assuming maximum output, the total number of inert fuel cell stacks must be increased and inserted, raising concerns about increased costs. Furthermore, when many inert fuel cells are used, the overall SOFC stack becomes larger, leading to increased costs for surrounding components, such as the hot module, which is made of insulating material that houses the SOFC stack and ensures uniform temperature throughout.

[0009] This invention has been made in view of the above-mentioned problems, and aims to achieve temperature uniformity within a fuel cell stack in a fuel cell module having a fuel cell stack structure in which fuel cell cells are stacked. [Means for solving the problem]

[0010] A preferred aspect of the present invention is a fuel cell module comprising a fuel cell stack comprising a plurality of fuel cell cells stacked on top of each other, which are supplied with fuel gas and oxidizer gas to generate electricity, and a temperature control member that performs heat exchange between a supply gas which is at least one of the fuel gas and oxidizer gas supplied to the fuel cell cells and an exhaust gas which is at least one of the fuel gas and oxidizer gas discharged from the fuel cell cells.

[0011] Another preferred aspect of the present invention is a gas supply method for a fuel cell stack comprising a plurality of stacked fuel cell cells that are supplied with fuel gas and oxidizer gas to generate electricity, wherein heat exchange is performed between a supply gas which is at least one of the fuel gas and oxidizer gas supplied to the fuel cell cells and an exhaust gas which is at least one of the fuel gas and oxidizer gas discharged from the fuel cell cells, and the heated supply gas is supplied to the fuel cell stack. [Effects of the Invention]

[0012] According to the present invention, in a fuel cell module having a fuel cell stack structure in which fuel cell cells are stacked, it is possible to achieve temperature uniformity within the fuel cell stack. Other problems and novel features will become apparent from the description herein and the accompanying drawings. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic perspective view of the fuel cell module. [Figure 2] This is a top-down plan view of the fuel cell module. [Figure 3A] This is a cross-sectional view AA of the fuel cell module 10 according to Embodiment 1. [Figure 3B] This is a cross-sectional view of a fuel cell cell 34 according to Embodiment 1. [Figure 4] This is a plan view of the upper side of the power generation cell substrate 28 according to Embodiment 1. [Figure 5] This is a plan view of the upper side of the electrode substrate 29 according to Embodiment 1. [Figure 6] FIG. 1 is a top plan configuration view of a separator 30 according to Embodiment 1. [Figure 7A] FIG. 2 is a top plan configuration view of a sealing material 31A according to Embodiment 1. [Figure 7B] FIG. 3 is a top plan configuration view of a sealing material 31B according to Embodiment 1. [Figure 7C] FIG. 4 is a top plan configuration view of a sealing material 31C according to Embodiment 1. [Figure 8] FIG. 5 is a top plan configuration view of a stack temperature adjustment layer 14A according to Embodiment 1. [Figure 9] FIG. 6 is a B-B cross-sectional view of the stack temperature adjustment layer 14A according to Embodiment 1. [Figure 10] FIG. 7 is a cross-sectional view of a fuel cell module in a comparative example. [Figure 11] FIG. 8 is a graph showing an in-stack temperature distribution according to Embodiment 1. [Figure 12] FIG. 9 is a cross-sectional view of a stack temperature adjustment layer according to Embodiment 2. [Figure 13] FIG. 10 is a top plan configuration view of a stack temperature adjustment layer according to Embodiment 3. [Figure 14] FIG. 11 is a configuration diagram showing a configuration of a fuel cell system according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Embodiments will be described in detail below with reference to the accompanying drawings. However, the present invention should not be construed as being limited to the description of the embodiments set forth below. Those skilled in the art will readily appreciate that the specific structure of the present invention may be altered without departing from the spirit and scope of the present invention.

[0015] In the structure of the embodiments described below, the same reference numerals are commonly used for identical parts or parts having similar functions across different drawings, and duplicate descriptions may be omitted.

[0016] When there are multiple elements with the same or similar function, they may be described using the same symbol but with different subscripts. However, if there is no need to distinguish between multiple elements, the subscript may be omitted in the description.

[0017] In this specification, notations such as "Part 1," "Part 2," and "Part 3" are used to identify components and do not necessarily limit their number, order, or content. Furthermore, the numbers used to identify components are used on a context-by-context basis, and a number used in one context does not necessarily indicate the same component in another context. Moreover, this does not prevent a component identified by one number from also performing the function of a component identified by another number.

[0018] The positions, sizes, shapes, and ranges of each component shown in drawings, etc., may not represent their actual positions, sizes, shapes, and ranges in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, and ranges disclosed in drawings, etc.

[0019] The publications, patents, and patent applications cited herein constitute part of the description herein.

[0020] In this specification, elements expressed in the singular form shall include the plural form unless otherwise clearly indicated in the context.

[0021] As will be explained in detail in the examples, in one example, a stack temperature control layer is provided between the end of the fuel cell stack, where fuel cell cells are stacked, and the plate substrate to which the piping for supplying and discharging fuel gas and oxidizer gas is connected, thereby providing a fuel cell module with high power output and high reliability.

[0022] The stack temperature adjustment layer has a meandering exhaust gas channel positioned in contact with the fuel cell stack end, and a meandering supply gas channel on the plate substrate side. The exhaust gas channel and the supply gas channel are in close proximity, and the high-temperature exhaust gas generated by power generation exchanges heat with both the fuel cell stack end, which is cooler than the center of the fuel cell stack, and the supply gas, which is cooler than the inside of the fuel cell stack. This corrects the temperature at the fuel cell stack end, thereby achieving temperature uniformity within the fuel cell stack. [Examples]

[0023] The fuel cell module according to this embodiment has a fuel cell stack made up of multiple cells, each consisting of an electrolyte layer and a pair of electrode layers sandwiching the electrolyte layer, and a stack temperature adjustment layer between the stack and a base plate or end plate to which gas supply and discharge piping is connected, which exchanges heat between the exhaust gas from the fuel cell stack and the supply gas.

[0024] Figure 1 is a schematic perspective view illustrating the configuration of the fuel cell module 10 according to Embodiment 1. Figure 2 is a plan view of the fuel cell module 10 as seen from above (top plate side). In Figures 1 and 2, some components of the fuel cell module 10 are shown as transparent dashed lines or omitted from the illustration in order to make the configuration easier to understand. In this specification, for convenience, the positive Z-axis direction is referred to as the upward direction and the negative Z-axis direction as the downward direction, but the fuel cell module 10 may be installed in a different orientation. The same applies to Figures 2 and beyond.

[0025] The fuel cell module 10 has a fuel cell stack 11 (a stack of power generation units) between a base plate 12, which serves as a plate substrate, and a top plate 13. A stack temperature adjustment layer 14 for adjusting the temperature within the fuel cell stack is placed between the base plate 12 and the fuel cell stack 11, and between the top plate 13 and the fuel cell stack 11.

[0026] As will be described later, the fuel cell stack 11 has a sealing material 31 between the base plate 12, the top plate 13, and the stack temperature adjustment layer 14, which serves to prevent gas leaks and act as a gas flow path. Each component has a through hole through which a bolt 24 passes, and the top and bottom are tightened with nuts 25 at a constant pressure. In this embodiment 1, the bolts 24 are provided at eight locations around the fuel cell module 10 on the outside of the fuel cell cells 34 that form the power generation area, but the installation locations and number may be changed by setting the tightening pressure.

[0027] Below the base plate 12, a gas supply through-hole 26 (not shown in Figures 1 and 2) is connected to a gas pipe connection section 17, which has a gas flow path inside, to which, for example, a fuel gas supply pipe 16 and a fuel gas discharge pipe 18 are connected. Fuel supply gas 15 is supplied into the fuel cell stack 11 and discharged as fuel exhaust gas 19 after power generation.

[0028] Furthermore, above the top plate 13, for example, an oxidizer gas supply pipe 21 and an oxidizer gas discharge pipe 22 are connected at a gas pipe connection part 17, and the oxidizer supply gas 20 is supplied into the fuel cell stack 11, and after generating electricity, it is discharged as oxidizer exhaust gas 23.

[0029] In this embodiment 1, the direction of the gas piping and the shape of the pipe connection are shown as examples, and the size and shape may change as long as the function remains the same. The fuel supply gas 15 may be hydrogen, methane, carbon monoxide, etc., and the oxidizer supply gas 20 may be air, etc., or a partially mixed gas or a reformed gas containing water vapor may also be used. The base plate 12, top plate 13, bolts 24, and nuts 25 are made of stainless steel.

[0030] Figure 3A is a cross-sectional view of AA in Figure 2. The diagram will be described from bottom to top. As shown in Figure 3A, the fuel cell module 10 has a base plate 12 on which a first stack temperature adjustment layer 14A is placed via a sealing material 31A. The base plate 12 has a fuel gas supply pipe 16, a gas pipe connection part 17A for fuel gas supply, a fuel gas discharge pipe 18, and a gas pipe connection part 17B for fuel gas discharge on its lower side. The stack temperature adjustment layer 14A has a meandering supply gas flow path 36 and an exhaust gas flow path 37.

[0031] Next, a metal electrode substrate 29 is placed on top via a sealing material 31C. Then, a power generation cell substrate 28 with a fuel cell 34 attached is placed on top via a sealing material 31B, and a metal separator 30 is placed on top via another sealing material 31B.

[0032] Figure 3B shows the structure of a fuel cell. The fuel cell cell 34 has a stacked structure consisting of an anode electrode 43, an electrolyte membrane 44, and a cathode electrode 45. As shown in Figure 3A, current collectors 33 made of porous metal are inserted above and below the fuel cell cell 34. The anode electrode 43 and cathode electrode 45 of the fuel cell cell 34 are electrically connected to the electrode substrate 29 or separator 30 via the current collectors 33.

[0033] As shown in Figure 3A, the current collector 33 is then inserted via the sealing material 31B, the power generation cell substrate 28 is placed on top again, the sealing material 31B and the current collector 33 are inserted, and the separator 30 is placed on top.

[0034] A power generation unit 32 is formed by sandwiching the power generation cell substrate 28 between an electrode substrate 29 and a metal substrate of a separator 30, or by sandwiching the power generation cell substrate 28 between upper and lower separators 30. By stacking (stacking) these power generation units 32, a fuel cell stack that can obtain high output is formed.

[0035] The top layer of the stack is an electrode substrate 29. Although not shown in the diagram, the two electrode substrates, the upper and lower layers, are connected externally by wiring, allowing for external output. A stack temperature control layer 14B is placed on the upper electrode substrate 29 via a sealing material 31C, with an exhaust gas flow path 37 on the electrode substrate 29 side and a supply gas flow path 36 on the top plate 13 side.

[0036] A top plate 13 is placed on the stack temperature control layer 14B via a sealing material 31A. An oxidizer gas supply pipe 21 is connected to the top plate 13 by a gas pipe connection part 17C for supplying oxidizer gas, and an oxidizer gas discharge pipe 22 is connected to it by a gas pipe connection part 17D.

[0037] As described above, the base plate 12, stack temperature adjustment layer 14, fuel cell stack 11, and top plate 13 are fastened together with bolts 24 and nuts 25 until a predetermined compressive force is applied.

[0038] Next, the gas flow in the fuel cell module of this embodiment 1 will be described. The gas flow is indicated by arrows in Figure 3A. For example, the fuel supply gas 15 at room temperature flows from the fuel gas supply pipe 16 at the bottom of the fuel cell module 10, which is kept at a constant temperature (for example, 500°C or higher), through the gas supply through-hole 26 in the base plate 12, and is heated in the stack temperature adjustment layer 14A.

[0039] The fuel supply gas 15 flows through the supply gas passage 36 on the base plate 12 side, then through the supply gas through-hole 38 (shown by the dashed line) to the gas through-hole 42A in the electrode substrate 29. Here, it splits into two flows: one into the gas through-hole 42A in the upward direction of the power generation cell substrate 28, and the other into the gas passage counterbore 46 in the electrode substrate 29.

[0040] The fuel supply gas flowing through the lateral gas channel recess 46 reaches the anode electrode of the fuel cell cell 34 exposed through the through-hole in the power generation cell substrate 28, generating electricity. During power generation, heat is also generated due to chemical reactions. Although there is a current collector 33 inside the gas channel recess 46, the fuel supply gas 15 is dispersed and reaches the anode electrode due to its porous nature. The shape of the current collector 33 may be changed to consume the fuel gas more efficiently.

[0041] The fuel exhaust gas 19, which is the result of consuming the fuel (e.g., hydrogen) used for power generation, is discharged through a gas through-hole 42B. It then enters the exhaust gas flow path 37 of the stack temperature control layer 14A, meanders along the underside of the electrode substrate 29, and exits through the gas discharge through-hole 27 of the base plate 12, passing through the fuel gas discharge pipe 18 to the outside.

[0042] Furthermore, the oxidizer supply gas 20 also flows through the oxidizer gas supply pipe 21 to the second stack temperature adjustment layer 14B and the cathode electrode of the fuel cell, and then flows back to the second stack temperature adjustment layer 14B as oxidizer exhaust gas 23. The power generation unit 32 consists of an electrode substrate 29, a power generation cell substrate, a separator 30 and a sealing material 31B between them, and a power generation cell substrate 28 and sealing material 31B sandwiched between the separator 30.

[0043] As described above, due to the heat generated during power generation, the fuel cell module 10 is hotter on the inside (the part away from the base plate 12 and top plate 13 in the Z-axis direction) and closer to room temperature on the outside (the part closer to the base plate 12 and top plate 13 in the Z-axis direction). In other words, the temperature distribution of the fuel cell cell 34 is not uniform.

[0044] Generally, higher temperatures lead to better power generation efficiency, but considering thermal expansion of components, it is desirable to maintain a high temperature within an appropriate range. The appropriate range depends on the design of the fuel cell module 10, but is, for example, 200 to 800°C. Ideally, it is desirable for the entire fuel cell cell 34 to be maintained at this temperature, but as mentioned above, the temperature is lower on the outside, which reduces power generation efficiency. Therefore, in this embodiment, a stack temperature adjustment layer 14 is used to perform heat exchange between the gas entering and leaving the fuel cell module 10, thereby preheating the fuel supply gas 15 and oxidizer supply gas 20 entering the fuel cell module 10.

[0045] Figure 4 is an upper plan view of the power generation cell substrate 28 according to Embodiment 1. The external shape of the power generation cell substrate 28 is the same as that of the base plate 12 and top plate 13, and the material used is a ceramic substrate with a thickness of approximately 3 mm. Eight through holes 35 for passing bolts 24 are arranged on the outer periphery, and a counterbore 41 for power generation cells is provided in the center for installing fuel cell cells 34. The depth of the counterbore 41 is such that, for example, when the fuel cell cell 34 is placed on the counterbore 41 and bonded, the fuel cell cell 34 is slightly higher.

[0046] In the fuel cell cell 34, an electrolyte membrane 44 is formed on the anode electrode 43, and a cathode electrode 45 is formed inside the electrolyte membrane. The anode electrode 43 and the electrolyte membrane 44 may be the same size. The thickness of the fuel cell cell 34 is approximately 100 μm to 1 mm.

[0047] Furthermore, the central part of the power generation cell substrate 28 has a through-hole that is larger than the cathode electrode 45 of the fuel cell cell 34 but smaller than the electrolyte membrane 44, and is processed so that the current collector 33 can contact the anode electrode 43.

[0048] Multiple gas through-holes 42 for supplying and discharging fuel gas and oxidizer gas are provided on all four sides of the outer circumference of the counterbore 41 for the power generation cell. In this embodiment, five gas through-holes 42 are provided on each side. These gas through-holes allow for the supply and discharge of gas from each stacked power generation unit 32 to the fuel cell cell 34, enabling power generation. In this embodiment, the case where one fuel cell cell 34 is mounted has been described, but the power generation cell substrate 28 may be modified to allow for the mounting of multiple cells. The thickness may also be changed.

[0049] Figure 5 is a plan view of the upper side of the electrode substrate 29 according to Embodiment 1. The outer shape of the electrode substrate 29 is the same as that of the base plate 12 and top plate 13, and it is made of a heat-resistant metal such as stainless steel, with a thickness of approximately 3 mm. Eight through holes 35 for passing bolts 24 are arranged on the outer periphery, similar to the power generation cell substrate 28, and gas through holes 42 for supplying and discharging fuel gas and oxidizer gas are formed in the same positions as on the power generation cell substrate 28.

[0050] Furthermore, to allow fuel gas or oxidizer gas to flow into the fuel cell cell, the gas passage counterbore 46 extends in one direction, and through-holes 42 for supplying and exhausting, for example, fuel supply gas 15, are formed therein. However, the gas through-holes 42 are not provided at the locations of the supply gas passage 36 and exhaust gas passage 37 of the stack temperature adjustment layer 14, which will be described later. Also, the electrode substrate 29 can be used as the electrode on the oxidizer gas side by rotating it 90° and inverting it upside down. The thickness may also be changed.

[0051] Figure 6 is an upper plan view of the separator 30 according to Embodiment 1. The separator 30 has the same outer shape as the electrode substrate 29, and the arrangement of the through holes 35 on the outer circumference, the gas through holes 42 for supplying and discharging fuel gas and oxidizer gas, and the counterbore 46 for the gas flow path are identical.

[0052] The difference is that a counterbore 47 for the opposite gas flow path is located on the back side. The counterbore for the opposite gas flow path has the shape of the counterbore 46 for the gas flow path on the front side rotated by 90°, and serves to allow different gases to flow on the front and back sides.

[0053] Furthermore, the counterbore 46 for the gas passage and the counterbore 47 for the gas passage on the opposite side are not through-holes, so the fuel gas and oxidizer gas do not mix. The through-holes 42 for supply and discharge gas are positioned in the same location when superimposed on the power generation cell substrate 28. The thickness is 3 mm, the same as the electrode substrate 29, but this may be changed.

[0054] Figures 7A to 7C are upper plan views of the sealing material 31 according to Embodiment 1. The sealing material 31 is for preventing the mixing of fuel gas and oxidizer gas, and may be, for example, a heat-resistant sheet material made from glass-based material or vermiculite. Three different shapes of the sealing material 31 are used in this Embodiment 1.

[0055] Figure 7A shows the sealing material 31A between the base plate 12 and the stack temperature control layer 14, and between the top plate 13 and the stack temperature control layer 14. The internal processing of the sealing material 31A includes through holes 35 for passing bolts 24 on the outer circumference and through holes 48 corresponding to the gas piping connection portions 17 of the base plate 12 and the top plate 13.

[0056] Figure 7B shows the sealing material 31B used between the electrode substrate 29 and the power generation cell substrate 28, and between the power generation cell substrate 28 and the separator 30. The interior of the sealing material 31B is provided with through holes 35 for passing bolts 24 on the outer circumference, through holes 49 in a region larger than the fuel cell cell 34, and through holes 48 that are the same as the gas through holes 42 of the electrode substrate 29 when they are aligned.

[0057] Figure 7C shows that the sealing material 31C is used between the electrode substrate 29 and the stack temperature control layer 14. The interior of the sealing material 31C is provided with through holes 35 for passing bolts 24 on the outer circumference, as well as through holes 50 for supply gas and 51 for exhaust gas. The thickness of the sealing material is approximately 0.3 to 1 mm.

[0058] Figure 8 is an upper plan view of the stack temperature adjustment layer 14A (base plate 12 side) according to Embodiment 1. In the stack temperature adjustment layer 14, heat exchange takes place between at least one of the fuel supply gas 15 and oxidizer supply gas 20 and at least one of the fuel exhaust gas 19 and oxidizer exhaust gas 23. That is, heat is transferred from the relatively high temperature (e.g., 500°C) fuel exhaust gas 19 and oxidizer exhaust gas 23 (exhaust gas) to the relatively low temperature (e.g., 25°C) fuel supply gas 15 and oxidizer supply gas 20 (supply gas).

[0059] In the embodiment, the stack temperature control layer 14 is in the form of a plate or layers. The supply gas flow path 36 through which the supply gas flows and the exhaust gas flow path 37 through which the exhaust gas flows are formed so that the gas flows in a plane parallel to the main surface (the surface with the largest area) of the stack temperature control layer 14. In order to efficiently transfer heat, methods such as reducing the distance between the supply gas and the exhaust gas, placing a material with high thermal conductivity between the supply gas and the exhaust gas, and increasing the opposing surface area between the supply gas (piping) and the exhaust gas (piping) are employed. In the example shown in Figure 8, the piping is meandering in order to increase the opposing surface area. In the example shown in Figure 8, heat exchange is performed between the fuel supply gas 15 and the fuel exhaust gas 19.

[0060] Figure 9 is a cross-sectional view of BB in Figure 8. As can be seen in Figure 8, eight through-holes 35 for bolts 24 are formed on the outer circumference of the stack temperature control layer 14A, similar to the electrode substrate 29.

[0061] In Figure 9, the electrode substrate 29 shown in Figure 5 is positioned so as to overlap the upper surface of the stack temperature adjustment layer 14A. An exhaust gas flow path 37 is formed in a meandering manner on the upper surface of the stack temperature adjustment layer 14A. For example, fuel exhaust gas 19 passing through the gas through-hole 42B (see Figure 3A) of the electrode substrate 29 flows through the exhaust gas flow path 37 to the exhaust gas through-hole 40 and is discharged from the gas discharge through-hole 27 of the base plate 12. The exhaust gas flow path 37 is positioned within the size of the fuel cell cell 34.

[0062] The base plate 12 is in close proximity to the lower surface of the stack temperature control layer 14A via a sealing material 31A. On the lower surface of the stack temperature control layer 14A, a meandering supply gas flow path 36 is formed, connected to a fuel supply gas through-hole 26 of the base plate 12, and passes through a supply gas through-hole 38, connecting to the supply gas stack flow path 39 on the surface (see also Figure 3A).

[0063] As shown in Figure 8, the supply gas channel 36 and the exhaust gas channel 37 are arranged in the stacking direction (Z direction) of the stack, but the heat exchange efficiency is increased by making the overlapping area in the Z direction (on the XY plane) larger.

[0064] The supply gas stack passage 39 is connected to the gas through-hole 42A of the electrode substrate 29. The material 14 of the stack temperature control layer is preferably a metal or an alumina-based ceramic with good thermal conductivity, and a material with good heat exchange is preferable. The thickness is preferably about 1 to 5 mm, and in this embodiment 1, it was set to 3 mm. Therefore, the thickness of the portion separating the supply gas passage 36 and the exhaust gas passage 37 is 1 mm or less.

[0065] The above describes the configuration of the stack temperature control layer 14A, but in the stack temperature control layer 14B, heat exchange takes place between the oxidizer supply gas 20 and the oxidizer exhaust gas 23. The physical configuration is the same as the stack temperature control layer 14A but inverted vertically (in the Z direction). Depending on the piping configuration, heat exchange may also take place between the fuel supply gas 15 and the oxidizer exhaust gas 23, or between the oxidizer supply gas 20 and the fuel exhaust gas 19.

[0066] In the example above, the exhaust gas passage 37 is located on the fuel cell cell 34 side. As a result, the heat from the exhaust gas is transferred to the fuel cell cell 34 via the electrode substrate 29, which also has the effect of raising the temperature of the fuel cell cell 34.

[0067] Figure 10 is a cross-sectional view of the fuel cell module 100 in a comparative example. The base plate 12, top plate 13, and fuel cell stack 11, which serve as the plate substrate, are the same as those of the fuel cell module 10 in Embodiment 1, the only difference being that the stack temperature adjustment layer 14 has been removed.

[0068] The fuel supply gas 15 flows from the supply gas through-hole in the base plate 12, immediately through the gas through-hole in the electrode substrate 29, through the lateral gas flow channel counterbore 46 and the gas through-hole 42 in the upper fuel cell cell substrate, and then to the next power generation unit.

[0069] Here, the temperature of the room-temperature fuel supply gas 15 entering from the outside is lower than that inside the fuel cell stack, and because the pipe length is short, the temperature of the electrode substrate 29 decreases. Furthermore, the fuel exhaust gas 19 becomes hot due to power generation inside the fuel cell stack and flows into the exhaust gas penetration hole of the base plate 12, but due to the short pipe, the temperature does not rise except at the gas pipe connection part 17. Rather, the temperature of the fuel gas exhaust pipe 18 rises.

[0070] Furthermore, even when the gas supply through-hole 26 and the gas discharge through-hole 27 are brought close together, the through-holes are short, so not much heat exchange occurs, and the fuel supply gas 15 does not warm up much. The oxidizer supply gas 20 is also supplied from an external source, similar to the fuel supply gas 15, so it flows to the fuel cell module 100 at a low temperature, causing the temperature of the electrode substrate 2 below the top plate 13 to drop.

[0071] Figure 11 shows the temperature distribution inside the fuel cell stack according to Embodiment 1. The horizontal axis represents temperature, and the vertical axis represents the position from the base plate to the top plate of the fuel cell stack 11. The dashed line represents the temperature inside the fuel cell stack of the comparative example fuel cell module 100.

[0072] As described above, the electrode substrate 29 at the end of the fuel cell stack 11 is cooled by the fuel supply gas 15 and oxidizer supply gas 20, resulting in a lower temperature, while the temperature tends to increase towards the center due to heat generated by power generation.

[0073] In the comparative example experiment, when the fuel supply gas 15 and oxidizer supply gas 20 were flowed at 2 L / min, the temperature difference between the end and center of the fuel cell stack was approximately 20°C. In contrast, in this embodiment 1, since a stack temperature adjustment layer 14 is provided at the end of the fuel cell stack 11, the temperature of the supply gas becomes higher than in the comparative example due to the heat exchange between the supply gas and exhaust gas. Furthermore, the temperature of the electrode substrate 29 becomes slightly higher than that of the adjacent power generation unit due to the heat exchange of the exhaust gas to the electrode substrate 29 (the part where the solid line graph in Figure 11 changes discontinuously).

[0074] These two effects reduced the temperature difference between the ends and the center of the fuel cell stack 11 to approximately 6°C. As described above, the heat exchange between the high-temperature exhaust gas and the supply gas, and the heat exchange with the fuel cell end substrate, mitigated the temperature distribution within the fuel cell stack 11.

[0075] Furthermore, the preferred relationship for heat exchange efficiency is between the supply gas flow path 36 and the exhaust gas flow path 37 > between the exhaust gas flow path 37 and the electrode substrate 29 ≥ between the supply gas flow path 36 and the base plate 12 or top plate 13. From the above relationship, the preferred relationship for the magnitude of thermal conductivity is stack temperature adjustment layer 14 > electrode substrate 29 ≥ base plate 12 or top plate 13.

[0076] Furthermore, by increasing the volume of the base plate 12 or top plate 13, such as by making it thicker, the heat capacity can be increased compared to the stack temperature adjustment layer 14 and electrode substrate 29, and by bringing it closer to the supply gas flow path of the stack temperature adjustment layer 14, the temperature of the supply gas can be increased.

[0077] Although the fuel cell module 10 described above is an example in which fuel cell stacks 11 are stacked vertically, it may also be a fuel cell module 10 oriented horizontally.

[0078] According to the fuel cell module of the above embodiment, one side of the stack temperature adjustment layer 14 is in contact with the end of the fuel cell stack, and the stack temperature adjustment layer 14 has a meandering exhaust gas flow path, and the gas discharged from the fuel cell stack flows through the exhaust gas flow path, thereby raising the temperature of the end of the fuel cell stack and reducing the temperature difference with the inside of the fuel cell stack.

[0079] Furthermore, the stack temperature adjustment layer 14 has a meandering supply gas flow path on the base plate 12 side. The supply gas flow path is not connected to the exhaust gas flow path and is arranged with a constant thickness to prevent gas mixing. Heat exchange occurs between the exhaust gas and the supply gas, and the supply gas temperature approaches the temperature inside the fuel cell stack just before the fuel cell stack, thereby reducing the temperature difference between the center and the edges of the fuel cell stack.

[0080] According to this embodiment, in a fuel cell module having a fuel cell stack structure in which fuel cell cells are stacked, it is possible to achieve temperature uniformity within the fuel cell stack, thereby providing a fuel cell system that offers high-efficiency power generation, improved reliability through stable power generation, and low cost. [Examples]

[0081] Embodiment 2 is a configuration for further improving the efficiency of heat exchange from exhaust gas to supply gas, and is described below.

[0082] Figure 12 is a cross-sectional view of the stack temperature control layer 14-2 according to Embodiment 2 of the present invention. As shown in this figure, the stack temperature control layer 14-2 is composed of five substrate layers. Through holes 35 for bolts 24 are formed in each layer, although these are not shown in the figure.

[0083] The lower supply gas heat exchange layer 53, although not shown in the figure, is provided with a supply gas through-hole 60A connected to, for example, the gas pipe connection 17 of the fuel gas supply pipe 16, and is connected to the meandering supply gas flow path 36-2. In addition, an exhaust gas through-hole 58 is formed at the location of the gas pipe connection 17 of the fuel gas exhaust pipe 18 from which the fuel exhaust gas 19 is discharged.

[0084] A sealing material 54 is placed on top of the supply gas heat exchange layer 53, and through holes are formed in the sealing material 54 at positions that overlap with the exhaust gas through holes 58 of the lower supply gas heat exchange layer 53 and at positions that overlap with the supply gas through holes 59, which will be described later. The thinner the thickness, the better, such as 0.3 mm.

[0085] A thin heat exchange layer 55, made of a metal with a high thermoelectric coefficient, is placed on top of the sealing material 54. Internally, exhaust gas penetration holes 58 and supply gas penetration holes 59 are drilled in the same positions as the aforementioned sealing material 54. Another layer of sealing material 54 is placed on top of this, and the exhaust gas heat exchange layer 56 is placed on top of the outermost layer.

[0086] The exhaust gas heat exchange layer 56 has a supply gas through-hole 59 positioned to overlap with the supply gas through-hole of the lower sealing material 54, and a meandering exhaust gas flow path 37-2 is arranged from a position overlapping with the exhaust gas through-hole 58. Furthermore, an exhaust gas through-hole 60B is opened at a position where the exhaust gas through-hole 42 of the electrode substrate 29 placed on top of this overlaps with the exhaust gas flow path 37-2.

[0087] Furthermore, the supply gas flow path 36-2 and the exhaust gas flow path 37-2 are designed to form as much overlapping area as possible, similar to the plan view of the stack temperature adjustment layer 14 mentioned above. The larger this area, the easier heat exchange will occur.

[0088] With the shape shown in Figure 12, for example, the fuel supply gas 15 enters the supply gas heat exchange layer 53 through the gas supply through-hole 60A from the gas supply through-hole 26 of the base plate 12 (though this is not shown), flows through the supply gas flow path 36-2, and then flows to the electrode substrate 29 through the supply gas through-hole 59.

[0089] The fuel exhaust gas 19 flows from the gas through-hole 42 for exhaust gas in the electrode substrate 29 to the exhaust gas through-hole 60B in the exhaust gas heat exchange layer 56, through the exhaust gas flow path 37-2, and then flows from the exhaust gas through-hole 58 to the gas exhaust through-hole 27 in the base plate 12.

[0090] In this process, the fuel exhaust gas 19 exchanges heat with the electrode substrate 29, which is in contact with the exhaust gas heat exchange layer 56 via the sealing material 31C in the region of the exhaust gas flow path 37-2, thereby bringing its temperature closer to that of the center. Furthermore, since the exhaust gas flow path 37-2 is in close proximity to the supply gas flow path 36-2 via the heat exchange layer 55, which has good thermal conductivity due to its metal composition, the temperature of the fuel supply gas 15 can be increased through heat exchange, reducing the temperature drop of the electrode substrate 29 and enabling temperature uniformity within the fuel cell stack 11.

[0091] Furthermore, the materials for the supply gas heat exchange layer 53 and the exhaust gas heat exchange layer 56 should be alumina-based ceramics with good thermal conductivity. In terms of thermal conductivity, the relationship is preferably metal heat exchange layer 55 > supply gas heat exchange layer 53, exhaust gas heat exchange layer 56 > base plate 12, electrode substrate 29. [Examples]

[0092] Figure 13 is an upper plan view of the stack temperature adjustment layer 14-3 according to Embodiment 3. The stack temperature adjustment layer 14-3 has a groove for the exhaust gas flow path 37-3 running parallel to a groove for the supply gas flow path 36-3 which meanders along one side of the same surface of a single substrate. For example, the temperature of the fuel supply gas is increased by heat exchange between the fuel exhaust gas 19 and the adjacent fuel supply gas 15, and this is directed to the electrode substrate 29, thereby achieving temperature uniformity within the fuel cell stack 11 in the same manner as described above. The substrate of the stack temperature adjustment layer 14-3 is preferably made of an alumina-based ceramic material with good thermal conductivity.

[0093] Furthermore, the gas supply through-hole 63 overlaps with the gas supply through-hole 26 of the lower base plate 12, and the exhaust gas through-hole 66 overlaps with the gas through-hole 42 for exhaust gas of the base plate 12. In this structure as well, a rise in the temperature of the supplied gas can be expected, and as described above, temperature uniformity within the fuel cell stack 11 can be achieved.

[0094] Furthermore, as an alternative configuration, an exhaust gas channel is provided on the back side of the electrode substrate and a supply gas channel on the surface of the base plate, with a metal substrate that does not have a channel with high thermal conductivity introduced between them. The back side of the electrode substrate, the metal substrate, and the surface of the base plate can be expected to have a similar effect as a stack temperature adjustment layer in this embodiment.

[0095] Figure 14 shows the configuration of the fuel cell system of the embodiment. The fuel cell system 70 has a fuel cell module 10 equipped with a stack temperature adjustment layer 14, which is insulated within a hot module 71 made of insulating material. The fuel gas supply pipe 16 and fuel gas discharge pipe 18 connected to the fuel cell module heat the fuel supply gas 15 in a fuel gas heat exchanger 72 even outside the hot module 71. In addition, the oxidizer gas supply pipe 21 and oxidizer gas discharge pipe 22 heat the oxidizer supply gas 20 in an oxidizer gas heat exchanger 73. Furthermore, by providing a mechanism to suppress temperature drop using insulating material between the hot module 71 and the fuel gas heat exchanger 72 and the oxidizer gas heat exchanger 73, temperature uniformity within the fuel cell stack 11 can be further achieved. A temperature-adjustable heating mechanism such as a burner may also be attached to the oxidizer gas supply pipe 21.

[0096] <Regarding variations of the present invention> The present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0097] According to the above embodiment, an efficient fuel cell can be realized, resulting in lower energy consumption, reduced carbon emissions, prevention of global warming, and contribution to the realization of a sustainable society. [Explanation of symbols]

[0098] 10: Fuel cell module, 11: Fuel cell stack, 12: Base plate, 13: Top plate, 14: Stack temperature control layer, 15: Fuel supply gas, 16: Fuel gas supply piping, 17: Gas piping connection, 18: Fuel gas exhaust piping, 19: Fuel exhaust gas, 20: Oxidizer supply gas, 21: Oxidizer gas supply piping, 22: Oxidizer gas exhaust piping, 23: Oxidizer exhaust gas, 28: Power generation cell substrate, 29: Electrode substrate, 30: Separator, 31: Sealing material, 32: Power generation unit 33: Current collector, 34: Fuel cell cell, 36: Supply gas passage, 37: Exhaust gas passage, 40: Exhaust gas through hole

Claims

1. A fuel cell stack consists of multiple fuel cell cells stacked on top of each other, which are supplied with fuel gas and oxidizer gas to generate electricity, The fuel cell cell is supplied with a fuel supply gas which is at least one of the fuel gas and oxidizer gas, and the fuel cell is discharged with an exhaust gas which is at least one of the fuel gas and oxidizer gas, and the temperature control member performs heat exchange between these two gases. The temperature control member is a temperature control layer, The temperature control layer includes: The supply gas flow path is a flow path through which the supply gas flows in the planar direction of the temperature control layer, An exhaust gas flow path is formed, which is a flow path through which the exhaust gas flows in the surface direction of the temperature control layer. The supply gas passage and the exhaust gas passage are arranged separately in the thickness direction of the temperature control layer. The temperature control layers are located at the top and bottom of the fuel cell stack, and in each of the temperature control layers, the exhaust gas flow path is configured to be closer to the fuel cell stack than the supply gas flow path, the supply gas supplied from the top is introduced into the temperature control layer located at the top, and the supply gas supplied from the bottom is introduced into the temperature control layer located at the bottom. Fuel cell module.

2. The supply gas passage and the exhaust gas passage have a structure that is bent within the plane of the temperature control layer. The fuel cell module according to claim 1.

3. The supply gas channel and the exhaust gas channel are formed on the front and back sides of the same substrate that constitutes the temperature control layer. The fuel cell module according to claim 1.

4. The substrate is made of metal or alumina-based ceramic. The fuel cell module according to claim 3.

5. The supply gas flow path is formed in the first substrate constituting the temperature control layer, The exhaust gas passage is formed on the second substrate constituting the temperature control layer, A heat exchange layer is formed between the first substrate and the second substrate. The fuel cell module according to claim 1.

6. The first substrate and the second substrate are made of alumina-based ceramic, and the heat exchange layer is made of metal. The fuel cell module according to claim 5.

7. The supply gas passage and the exhaust gas passage are arranged separately within the same plane of the temperature control layer. The fuel cell module according to claim 1.

8. The fuel cell stack is positioned between the top plate and the base plate. The top plate and the base plate are provided with piping for at least one of the fuel gas and the oxidizer gas. The temperature control layer is located between the fuel cell stack and the top plate, and at least one of the spaces between the fuel cell stack and the base plate. The fuel cell module according to claim 1.

9. The thermal conductivity of the temperature control layer is set to be higher than that of the electrode substrate, the base plate, and the top plate that constitute the fuel cell stack. The fuel cell module according to claim 8.

10. The heat capacity of the base plate and the top plate is set to be greater than that of the temperature control layer and the electrode substrate constituting the fuel cell stack. The fuel cell module according to claim 8.

11. A gas supply method for a fuel cell stack, which consists of multiple stacked fuel cell cells that generate electricity by being supplied with fuel gas and oxidizer gas, A heat exchange is performed between a supply gas, which is at least one of the fuel gas and oxidizer gas supplied to the fuel cell, and an exhaust gas, which is at least one of the fuel gas and oxidizer gas discharged from the fuel cell. The heated supply gas is supplied to the fuel cell stack. The fuel cell stack is positioned between the top plate and the base plate, to which the piping for the supply gas and exhaust gas is connected. The heat exchange is performed by temperature control members positioned between the top plate and the fuel cell stack, and between the base plate and the fuel cell stack. In each of the temperature control members, the exhaust gas flow path is positioned closer to the fuel cell stack than the supply gas flow path, the supply gas supplied from the top plate side is introduced to the temperature control member positioned between the top plate and the fuel cell stack, and the supply gas supplied from the base plate side is introduced to the temperature control member positioned between the base plate and the fuel cell stack. A method for supplying gas to a fuel cell module.

12. The temperature control member has a plate-like structure, and heat exchange between the supply gas and the exhaust gas is achieved by extending and bending the piping for the supply gas and the piping for the exhaust gas in the planar direction. A method for supplying gas to a fuel cell module according to claim 11.

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