JPS6280967A - Fuel cell - Google Patents

Abstract

PURPOSE:To make temperature distribution uniform and make current density distribution uniform by making oxidizing gas and fuel gas which flow with a separator interposed in a form of parallel flow, and making oxidizing gas and fuel gas which flow with an electrolyte plate interposed in a form of counter flow. CONSTITUTION:Oxidizing gas and fuel gas supply passage holes 9, 10 and exhaust passage holes 11, 12 are installed on one side of the peripheries of an electrolyte plate 1 and a separator 4 and the other side of them respectively. The supply passage hole and exhaust passage hole of oxidizing gas and the supply passage hole and exhaust passage hole of fuel gas which are installed in the periphery of each separator in every adjacent step so as to form counter flow are alternately opened in gas passages in the center of the separator so that oxidizing gas and fuel gas which flow with the separator interposed form parallel flow, and oxidizing gas and fuel gas which flow with the electrolyte plate interposed form counter flow. Thereby, optimum temperature is uniformly kept on the whole surface of the electrolyte plate and the composition of fuel gas and oxidizing gas is kept uniform. Therefore, the whole surface of the electrolyte plate can be effectively utilized to obtain high current density, and the high performance of the fuel cell can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuel cell used in the energy sector that directly converts the chemical energy of fuel into electrical energy. This invention relates to an internal manifold type fuel cell which is sandwiched between fuel electrodes and has a characteristic gas inlet/outlet portion that allows oxidizing gas to flow to the oxygen electrode side and fuel gas to the fuel electrode side.

[Prior art] In a fuel cell, an electrolyte plate is sandwiched between an oxygen electrode and a fuel electrode, and oxidizing gas and fuel gas are supplied to each electrode, thereby generating gas between the oxygen electrode and the fuel electrode. The unit has a structure in which a plurality of units that generate power by a potential difference are laminated in multiple layers with separators interposed in between.

Conventionally, such fuel cells are divided into cross-flow type, counter-flow type, and parallel-flow type fuel cells, depending on the flow type of oxidizing gas supplied to the oxygen electrode side and fuel gas supplied to the fuel electrode side with an electrolyte plate sandwiched between them. It was getting worse.

As shown in FIG. 4, the parallel flow fuel cell has a structure in which a unit consisting of an electrolyte plate 1 sandwiched between an oxygen electrode 2 and a fuel electrode 3 from both upper and lower sides is laminated with a separator 4 in between. Oxidizing gas O supplied to the oxygen electrode 2 side of
The separator 4 is arranged so that G and the fuel gas G supplied to the fuel electrode side 3 sandwich the electrolyte plate 1 and flow in parallel in the same direction.
The directions of the gas passages 5 and 6 are determined, and the oxidizing gas OG and fuel gas FG flowing between the separators 4 are also made to flow in parallel in the same direction as above.

For this reason, in a conventional parallel flow fuel cell, as shown in FIGS. 5 and 6, an electrolyte plate 1, a separator 4,
and a spacer 7 on the oxygen electrode side for preventing the electrodes 2 and 3 from being pressed against the electrolyte plate 1 by the separator 4 and for allowing the oxidizing gas OG and fuel gas FG to flow along both sides of the separator 4, and a spacer 7 on the fuel electrode side. On one side of each peripheral part of the spacer 8, only the supply passage holes 9 for oxidizing gas OG and the supply passage holes 10 for fuel gas FG are provided alternately at appropriate intervals, and on the other side of the peripheral part, Gas OG discharge channel hole 11
and fuel gas FG exhaust passage holes 12 are provided alternately at appropriate intervals. Furthermore, in order to supply and discharge the oxidizing gas OG and fuel gas FG to both sides of each separator 4 in each layer, all the oxidizing gas supply channel holes 9 and Notches 13 and 14 are provided in each oxidant gas discharge passage hole 11, and after all of the oxidant gas OG on the supply side is guided to the gas passage 5 of the separator 4 at the oxygen electrode side spacer 7, the discharge passage is Hole 1
It is made to be drained to 1. Similarly, all fuel gas supply passage holes 10 and each fuel discharge passage hole 12 provided in each fuel electrode side spacer 8 have notches 15.
1B, and the fuel gas F is provided at the fuel electrode side spacer 7.
Only G flows from all supply passage holes 10 to all discharge passage holes 12.

[Problems to be Solved by the Invention] However, in the parallel flow fuel cell, while the oxidizing gas OG and the fuel gas FG sandwich the separator 4 and the electrolyte plate 1 and flow in parallel from the supply side to the discharge side, the separator 4 There is almost no temperature difference between the two gases due to heat exchange between the oxidizing gas and the fuel gas. Each temperature of the separator increases uniformly, and on the entire plane of the electrolyte plate 1, a high temperature area occurs on the discharge side of both gases, the temperature is low on the inlet side of both gases, and the temperature is high on the discharge side. Temperature distribution. As a result, the power generation current density distribution cannot be made uniform over the entire surface of the electrolyte plate, resulting in a decrease in efficiency.

As described above, when a large temperature gradient occurs between the inlet side and the discharge side of the electrolyte plate, the thermal stress of the electrolyte plate becomes large and the life of the electrolyte plate is shortened.

Therefore, in order to solve this problem, the present invention aims to make the temperature distribution uniform by reducing the temperature difference on the entire surface of the electrolyte plate, and to make the current density distribution uniform on the entire surface of the electrolyte plate. The aim is to improve performance.

[Means for Solving the Problems] The present invention provides an oxidizing gas to the oxygen electrode side and a fuel gas to the fuel electrode side of a single cell configured such that both sides of an electrolyte plate are sandwiched between an oxygen electrode and a fuel electrode. In a fuel cell in which units configured to flow are stacked via a separator, the electrolyte plate, one side of the peripheral portion of the separator, and the other side opposite to the one side,
Supply passage holes and discharge passage holes are respectively provided for oxidizing gas and fuel gas, and the oxidizing gas and fuel gas flowing through the separator become parallel flows, and the oxidizing gas and fuel gas flowing through the electrolyte plate between them. are the oxidizing gas supply passage hole and discharge passage hole, and the fuel gas supply passage hole and discharge passage hole, which are provided at the periphery of each separator in each adjacent stage so as to provide counterflow. and are alternately opened to the gas passage in the center of the separator.

[Function] The oxidizing gas and the fuel gas flowing across the electrolyte plate are flown along the separator from the respective supply flow passage holes at opposing positions to form counterflows. As a result, the composition ratio of oxidizing gas and fuel gas can be kept uniform over the entire surface of the electrolyte plate, and the entire surface of the electrolyte plate can be utilized at its maximum performance, resulting in a high current density. In addition, since the oxidizing gas and the fuel gas flowing through the separator flow in parallel, the entire surface of the electrolyte plate can be kept at an optimal temperature.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which an oxygen electrode spacer 7 and a fuel electrode side spacer 8 are formed by cutting out the central part corresponding to the electrode to form a space, similar to FIGS. 5 and 6. In a fuel cell, the electrolyte plate 1 and the separator 4 of each layer are interposed between the electrolyte plate 1 and the separator 4 to prevent the unevenness of the central part of the separator 4 from pressing the electrodes 2 and 3 strongly. 4. Oxygen electrode side spacer 7a, 7
An oxidizing gas supply channel hole 9 and a discharge channel hole 11 are provided on one side of the peripheral portion of each of the spacers 8a and 8b on the fuel electrode side.
, fuel gas supply passage holes 10 and discharge passage holes 12 are provided at appropriate intervals, and the above-mentioned flow passage holes 9, 11, 10, 12 are also provided at appropriate intervals on the loose sides of the opposing peripheral parts. establish.

Oxidizing gas flowing between the separators 4 0G-1,0
Oxidizing gas 0G-1 flows in such a way that G-2 and fuel gases FG-1 and FG-2 flow in parallel and sandwich the electrolyte plate 1.
, 0G-2 and the fuel gases FG-1 and FG-2 are located directly above the electrolyte plate 1 so that the gases can flow in opposite directions. A notch 13 is provided for opening only the oxidizing gas discharge passage hole 11 provided on one side of the peripheral portion of the oxygen electrode side spacer 7a into the space in the center, and a cutout 13 is provided for opening only the oxidizing gas discharge passage hole 11 provided on one side of the peripheral portion of the oxygen electrode side spacer 7a, and a cutout 13 is provided on the other side of the opposing peripheral portion. A notch 15 is provided in which only the discharge passage hole 12 opens into the central space, and a notch 16 is provided in which only the fuel gas supply passage hole 10 provided on the other side of the opposing peripheral portion opens into the central space. .

On the other hand, in the fuel electrode side spacer 8b located directly below the electrolyte plate 1, a notch 16 is provided to open only the fuel gas supply passage hole 10 provided on one side of the periphery to the space in the center, and It is located on the other side of the periphery. A notch 15 is provided to open only the fuel gas discharge passage hole 12 into the central space, and a notch 15 is provided on one side of the periphery of the oxygen electrode side spacer 7b located below the fuel electrode side spacer 8b. A notch 14 is provided that opens only the oxidizing gas supply flow path hole 9 into the space in the center, and a notch that opens only the oxidant gas discharge flow path hole 11 provided on the other side of the opposing periphery into the space in the center. 13 will be provided.

Each of the oxidizing gas supply passage hole 9 and discharge passage hole 11 and the fuel gas supply passage hole 10 and discharge passage hole 12 are connected to piping arranged outside the fuel cell.

Electrolyte plate 1, separator 4, spacers 7a, 7b.

Oxidizing gas is introduced from the outside into each of the oxidizing gas supply passage holes 9 provided at opposing positions in the peripheral portions of 8a and 8b, and fuel gas is introduced from the outside into each of the fuel gas supply passage holes 10. When introduced, oxidizing gas 0G-1 or 0G-2 and fuel gas FG-1 or FG flow between the separators 4 of the stages.
-2 is a parallel current flowing in the same direction as shown by the arrow, but
The oxidizing gas 0G-1 and the fuel gas [G-1, or 0G-2 and FG-2, which flow across the electrolyte plate 1, form countercurrents flowing in opposite directions. That is, the flow directions of both of the gases are as shown in FIG. 2, which only shows the flow of the gases. As a result, the oxidizing gas and the fuel gas flow in opposite directions on both sides of the electrolyte plate 1, so that the composition ratio of the fuel gas and the oxidizing gas can be made uniform over the entire plane of the electrolyte plate 1, and the separator 4 Since the oxidizing gas 0G-1 or 0G-2 and the fuel gas FG-2 or FG-1 flow in parallel across the electrolyte plate 1, the entire surface of the electrolyte plate 1 can be uniformized to an optimal temperature. As described above, in the present invention, the features of countercurrent flow and the features of parallel flow can be obtained at the same time, resulting in the temperature distribution and current density distribution as shown in FIG. That is, the oxidizing gas 0G-2 and the fuel gas FG-1 flowing through one separator 4 are uniformly heated from the inlet portion a as shown by the curve 2. On the other hand, the temperature of the oxidizing gas 0G-1 and the fuel gas FG-2 flowing through another adjacent separator 4 decreases uniformly as the flow direction distance X increases from the discharge side to the inlet part, as shown by the curve I'll go.

Since the temperatures of the oxidizing gas 0G-1 and the fuel gas FG-1, which flow across the electrolyte plate 1, flow opposite each other, the temperature of the electrolyte plate 1 becomes close to the average temperature of both gases, resulting in a nearly flat temperature distribution. Obtainable.

As shown by curve (2), the current density has a flattened distribution that is almost the same as the electrolyte plate temperature because the temperature of the electrolyte plate 1 is uniform and the gas composition ratio is almost uniform.

In the above, the entire surface of the electrolyte plate 1 is maintained at its optimum operating temperature by appropriately selecting the inlet temperatures of the oxidizing gases 0G-1, 0G-2 and the fuel gases FG-1, FG-2.
The amount of power generated across the entire area can be maintained at a high value. Also, electrolyte plate 1
As shown in FIG. 3, the temperature of the oxygen electrode 2, fuel electrode 3, and separator 4 is almost uniform over the entire surface, and a durable battery is obtained in which thermal stress is less likely to occur.

Note that the present invention is not limited to the above embodiments. For example, spacers 7a, 7b, 8a.

8b is used, and cutouts 13, 14, 15, and 16 are provided in this so that the gas communicates with the gas passage of the separator 4 and the supply channel hole and the discharge channel hole of each gas. However, a notch groove may be provided in the separator 4 itself to communicate each gas passage hole with the gas passage of the separator, and each shape of the notch 13, 14, 15, 16
The numbers may be other than those shown.

[Effects of the Invention] As described above, according to the fuel cell of the present invention, in order to regulate the flow direction of the oxidizing gas and the fuel gas flowing along the separator differently in each stage, the supply passage holes for each gas and The exhaust flow path holes are defined so that the oxidizing gas and fuel gas that always flow between the separators flow in parallel, and the oxidizing gas and fuel gas that flow between the electrolyte plates flow in opposite directions. The effect can be reduced.

(1) Since the electrolyte plate can be kept at an optimal temperature over its entire surface, and the composition ratio of fuel gas and oxidizing gas can be kept uniform, the entire surface of the electrolyte plate can be used at its maximum performance, resulting in high current density. As a result, the performance of fuel cells can be improved.

(n) Since the flow rate of fuel gas and oxidizing gas can be suppressed to the minimum flow rate necessary for the reaction in order to remove the reaction heat generated from the electrolyte plate, the power can be reduced and high efficiency can be achieved.

(2) Since the current density is uniform, wear and tear on the electrolyte plate does not increase locally, and the life of the battery can be extended.

OV) Because the temperature distribution of the electrolyte plates, electrodes, and separators that make up the battery is small, thermal stress is less likely to occur, and
Because hot spots are less likely to occur on the electrolyte plate. Breakage of the electrolyte plate is less likely to occur, and battery performance is stabilized and reliability is high.

[Brief explanation of drawings]

FIG. 1 is an explanatory perspective view showing one embodiment of the present invention, FIG. 2 is a perspective view showing the flow of gas obtained by the present invention, and FIG.
The figure shows the distribution of temperature and current density in the case of the gas flow type shown in Fig. 2, Fig. 4 is a perspective view showing the gas flow of a parallel flow type fuel cell, and Fig. 5 shows the distribution of the gas flow in the case of the gas flow type shown in Fig. 4. FIG. 6 is a perspective view showing an example of a conventional gas inlet/outlet section for realizing gas flow, and FIG. 6 is a sectional view of a conventional parallel flow fuel cell. 1 is an electrolyte plate, 2 is an oxygen electrode, 3 is a fuel electrode, 4 is a separator, 7.7a, 7b is an oxygen electrode side spacer, 8, 8a,
8b is a fuel electrode side spacer, 9 is an oxidizing gas supply channel hole,
Reference numeral 10 indicates a fuel gas supply channel hole, 11 indicates an oxidizing gas discharge channel hole, and 12 indicates a fuel gas discharge channel hole.

Claims (1)

[Claims] 1) A unit in which oxidizing gas flows to the oxygen electrode side and fuel gas flows to the fuel electrode side of a single cell configured so that both sides of an electrolyte plate are sandwiched between an oxygen electrode and a fuel electrode are laminated via a separator. In the fuel cell, supply passage holes and discharge passage holes for oxidizing gas and fuel gas are respectively provided on one side of the peripheral portion of the electrolyte plate and the separator and on the other side opposite to the one side, and the above-mentioned The oxidizing gas and fuel gas flowing between the separators become parallel flows, and the oxidizing gas and fuel gas flowing between the electrolyte plates become counter-flows. 1. A fuel cell characterized in that supply and discharge passage holes for oxidizing gas and supply and discharge passage holes for fuel gas are alternately opened in a gas passage in the center of a separator.