JPH06275304A - Fuel cell - Google Patents

Abstract

PURPOSE:To provide a fuel cell having improved generation efficiency where fuel gas and oxidant gas can be equally distributed to inside manifold type cells. CONSTITUTION:In an interconnector IA, an anode edge plate 2A, a cathode edge plate 3A, and an electrolytic layer 11A, passage cross sections of an anode inlet manifold 14 and an anode outlet manifold 15 are different and passage cross sections of a cathode inlet manifold 16 and a cathode outlet manifold are different. The interconnector 1A is held between the anode edge plate 2A and the cathode edge plate 3A, thus constituting a separator 4A. An anode 12 and a cathode are brought into close contact with the electrolytic layer 11A. An anode current collecting plate 13 and a cathode current collecting plate are disposed in the anode 12 and the cathode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to a manifold structure.

[0002]

2. Description of the Related Art In a stacked fuel cell, fuel gas and oxidant gas are supplied to and discharged from each cell via a manifold. This manifold is roughly divided into an external manifold and an internal manifold.

The external manifold uses a box-shaped flow path provided in close contact with the side surfaces of the stacked fuel cells as a manifold. Further, the internal manifold uses a hole that penetrates the end of the cell as the manifold.

FIG. 3 shows a single cell of a conventional internal manifold type fuel cell, in which a fuel gas 5 and a separator 4 are formed by sandwiching an interconnector 1 between an anode edge plate 2 and a cathode edge plate 3. Oxidizer gas 6
A manifold 7 provided at the end of the separator 4,
Supply and discharge by 8, 9, 10. As a result, the fuel gas 5 and the oxidant gas 6 are supplied to the electromotive component sandwiching the anode 12 and the cathode (not shown) with the electrolyte layer 11 being partitioned from each other via the interconnector 1.

Inside the separator 4, in order to efficiently derive the current from the electromotive component while ensuring the gas flow path inside the separator 4, the anode current collectors that are in close contact with the anode 12 and the cathode (not shown), respectively. A plate 13 and a cathode current collector (not shown) are provided.

In the above internal manifold structure, since each electrolyte layer is isolated by the separator, the electrolyte moves between the cells through the interface between the stacked cells and the manifold that adheres to the side surface of the cells. It is possible to avoid the drawbacks peculiar to the manifold. However, it is not easy to increase the flow passage cross-sectional area of the manifold,
There is still a problem in evenly supplying the fuel gas or the oxidant gas to each cell.

[0007]

By supplying an equal amount of fuel gas and oxidant gas to each of the stacked cells, the output performance of each cell is kept the same and the performance of the entire fuel cell is maintained high. be able to. In order to evenly supply the fuel gas or the oxidant gas to each cell, it is necessary to increase the flow passage cross-sectional area of the manifold or reduce the number of stacked cells.

However, it is difficult to increase the flow passage cross-sectional area of the manifold due to manufacturing restrictions. Further, in order to use a fuel cell as a power generation facility, from the viewpoint of increasing space efficiency, it is possible to supply fuel gas and oxidant gas to a large number of cells in a continuous manifold by stacking as many cells as possible. Required.

Therefore, an object of the present invention is to provide a fuel cell in which the fuel gas and the oxidant gas can be evenly distributed to each cell of the internal manifold type, and the power generation efficiency is improved.

[0010]

In order to achieve the above object, the present invention is directed to a fuel cell in which cells are stacked and a manifold is formed by providing openings at the ends of the cells to form a fuel gas and an oxidizer. The flow passage cross-sectional area of the manifold for supplying at least one of the gases is different on the inlet side and the outlet side.

[0011]

Since the static pressure difference between the manifolds at the inlet and outlet of each cell is the same from the bottom to the top of the stacked cells, the fuel gas or oxidant gas can be evenly distributed to each cell. Therefore, each cell can have the same output performance, and the performance of the entire fuel cell is improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the structure of a single cell, which is a main part of one embodiment of the present invention. In the figure, reference numeral 1A is an interconnector, and the anode inlet manifold 14 and the anode outlet manifold 15 have different flow passage cross-sectional areas, and the cathode inlet manifold 16 and the cathode outlet manifold 17 are provided.
The structure is the same as that of the conventional interconnector 1 described above, except that the flow passage cross-sectional area is different. Reference numeral 2A denotes an anode edge plate, which has the same configuration as that of the conventional anode edge plate 2 described above except that the flow passage cross-sectional areas of the anode inlet manifold 16 and the anode outlet manifold 17 are different. Reference numeral 3A denotes a cathode edge plate, which has the same configuration as that of the conventional cathode edge plate 3 described above except that the flow path cross-sectional areas of the cathode inlet manifold 16 and the cathode outlet manifold 17 are different. Four
A is a separator, which is composed of an interconnector 1A sandwiching an anode edge plate 2A and a cathode edge plate 3A. 11A is an electrolyte layer, which is the same as the above-mentioned conventional electrolyte layer 11 except that the anode inlet manifold 14 and the anode inlet manifold 16 have different cross-sectional areas and the cathode inlet manifold 16 and the cathode outlet manifold 17 have different flow passage cross-sectional areas. It is configured.

The fuel gas 5 and the oxidant gas 6 are supplied to the manifolds 14, 15, 1 provided at the ends of the separator 4A.
Since it is supplied and discharged by 6, 17, the interconnector 1A
The electrolyte layer 11A is supplied to the electromotive component sandwiching the anode 12 and the cathode (not shown) while being separated from each other via the.

Inside the separator 4A, the separator 4
In order to efficiently derive the current from the electromotive component while ensuring the gas flow path in A, the anode current collector plate 13 and the cathode current collector plate (not shown) closely attached to the anode 12 and the cathode (not shown) are provided. It is arranged.

In the above structure, the flow passage cross-sectional areas of the anode inlet manifold 14 and the anode outlet manifold 15 and the flow passage cross-sectional areas of the cathode inlet manifold 16 and the cathode outlet manifold 17 are set to the fuel gas 5
In addition, the static pressure difference between the inlet manifold and the outlet manifold is selected to be the same for all cells in response to changes in the composition, physical properties or mass flow rate of the oxidant gas 6 in the cells. As a result, the same flow rate of gas can be supplied to each cell.

Generally, the volumetric flow rate in the manifold is larger on the outlet side than on the inlet side. Therefore, when both manifold flow passage areas are the same as in the conventional case, the dynamic pressure of gas in the manifold is The exit side is larger than the side. The same dynamic pressure in both manifolds can be solved by increasing the manifold channel cross-sectional area on the outlet side. As a result, the same flow rate of gas can be supplied to each cell.

FIG. 2 shows the relationship of the variation in mass flow rate between cells with respect to the flow passage cross-sectional area of the inlet manifold and the outlet manifold for the fuel gas. Here, the variation of the mass flow rate means the mass flow rate Q _max and Q _min flowing through the cell having the largest mass flow rate and the cell having the smallest mass flow rate among all the stacked cells from (Q _max −Q _min ) / Q. _It is calculated by _min . In the conventional fuel cell, since the inlet and outlet manifolds have the same flow passage cross-sectional area, the mass flow rate varies at 1.00 points on the horizontal axis. However, when the outlet manifold channel cross-sectional area is gradually increased with respect to the inlet manifold channel cross-sectional area, the mass flow rate has a minimum value at some places.

In order to maintain high efficiency and long life of the fuel cell, it is desirable to suppress the mass flow rate variation between cells to about 10% or less. However, when the conventional manifold, that is, when the horizontal axis in the figure is 1.00, the mass flow rate variation exceeds 10%. At this time, the volumetric flow rate ratio of the outlet manifold to the inlet manifold is 1.047, which is indicated by point A on the horizontal axis in the figure. When the flow passage cross-sectional area of the outlet manifold with respect to the inlet manifold is in the vicinity of the value at point A, the mass flow rate variation between cells has a minimum value. Therefore, the mass flow rate between the cells is adjusted by matching the flow passage cross-sectional area ratio of the inlet manifold to the inlet manifold with the volume flow ratio of the outlet manifold to the inlet manifold, that is, by selecting point A in the figure. Variation can be reduced.

From the above, it is not preferable that the mass flow ratio of the outlet manifold to the inlet manifold exceeds 1.05, and in that case, the flow passage cross-sectional area of the outlet manifold is made larger than that of the inlet manifold. By changing the flow rate ratio, it is possible to suppress variations in mass flow rate between cells. At this time, if the flow channel cross-sectional area ratio matches the volume flow rate ratio within 5%, the mass flow rate variation between cells is within about 10%. Similarly, when the static pressure ratio of the inlet manifold to the outlet manifold of 1.053 is shown on the horizontal axis in the same figure, it is point B, and when the flow passage cross-sectional area ratio of the outlet manifold to the inlet manifold almost matches the static pressure ratio, the mass between cells is Flow rate variation is minimal.

As described above, according to the present embodiment, since the static pressure difference between the cell inlet and outlet is the same from the lower cell to the upper cell, an equal amount of gas flows through each cell, which increases the fuel cell level. Efficiency and long life can be achieved.

In the embodiment described above, the number of manifolds is one on each of the inlet side and the outlet side of the fuel gas and the oxidant gas, but the present invention is not limited to this. If there are multiple manifolds,
The flow rate cross-sectional area and mass flow rate show the sum total of each.

[0022]

As described above, according to the present invention, in a fuel cell in which cells are stacked and an manifold is formed by providing openings at the ends of these cells, at least one of fuel gas and oxidant gas is used. Since the cross-section area of the manifold for gas supply is different on the inlet side and the outlet side, it is possible to supply the fuel gas or oxidant gas to each cell more uniformly than the conventional internal manifold type fuel cell. Therefore, it is possible to provide a fuel cell having high performance and long life.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an embodiment of the present invention.

FIG. 2 is a diagram showing a variation in mass flow rate between cells with respect to a flow passage cross-sectional area ratio on an outlet side and an inlet side of a manifold.

FIG. 3 is a perspective view showing a main part of a conventional internal manifold type fuel cell.

[Explanation of symbols]

1 ... Interconnector, 2 ... Anode edge plate, 3 ... Cathode edge plate, 4 ... Separator, 5 ... Fuel gas, 6 ...
Oxidant gas, 7, 14 ... Anode inlet manifold, 8,
15 ... Anode outlet manifold, 9, 16 ... Cathode inlet manifold, 10, 17 ... Cathode outlet manifold, 1
1, 11A ... Electrolyte layer, 12 ... Anode, 13 ... Anode current collector.

Claims (3)

[Claims] 1. In a fuel cell in which cells are stacked and a manifold is formed by providing openings at the ends of these cells, a flow passage cross-sectional area of the manifold in supplying at least one of a fuel gas and an oxidant gas is A fuel cell characterized in that the inlet side and the outlet side are different. 2. When the ratio of the volumetric flow rate of gas at the outlet and inlet of the manifold is 0.95 or less or 1.05 or more, the channel cross-sectional area of the outlet of the manifold is the product of the channel cross-sectional area of the inlet and its ratio. 2. The fuel cell according to claim 1, wherein the fuel cells are matched with a deviation of 5% or less. 3. When the ratio of the static pressure in the manifold at the outlet and inlet of the gas passage in each cell is 9.95 or less or 1.05 or more, the passage sectional area of the outlet of the manifold is defined as the inlet passage sectional area. 2. The fuel cell according to claim 1, wherein the fuel cell and the ratio thereof are matched with a deviation of 5% or less.