JP2007109669A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell not disturbing flow in a reaction fluid exhausting port of a cell plate in a fuel cell stack. <P>SOLUTION: The fuel cell includes a reaction fluid supply manifold 3 for supplying reaction fluid, a reaction fluid exhausting manifold 4 installed in a point symmetrical position to the reaction fluid supply manifold for exhausting reaction fluid, a cooling medium supply manifold 6 for supplying a cooling medium cooling the fuel cell stack, and a cooling medium exhausting manifold 8 installed in a point symmetrical position to the cooling medium supply manifold for exhausting the cooling medium, and the reaction fluid exhausting manifold 4 is formed to have a cross section lager than that of the cooling medium exhaust manifold 8, and extended to a more lower part than a reaction fluid outflow port of the cell plate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polymer electrolyte fuel cell characterized by a battery plate in which a reaction gas channel is formed.

  A conventional polymer electrolyte fuel cell includes a single cell in which an anode (fuel electrode) is arranged on one surface of a solid polymer electrolyte membrane and a cathode (oxidant electrode) on the other surface, and a battery plate (separator). A fuel cell stack is formed by stacking a large number of layers so as to be sandwiched between. A fuel flow path is formed on the battery plate surface in contact with the anode, and an oxidant flow path is formed on the battery plate surface in contact with the cathode.

  The battery plate includes a normal fuel (hydrogen-based reformed gas or hydrogen gas) supply manifold, a fuel discharge manifold, an oxidant (air or oxygen gas) supply manifold, and an oxidant discharge manifold. Formed in relation. Each manifold is provided with a supply port or a discharge port penetrating the battery plate. These supply ports or discharge ports communicate with each other in the stacking direction in the fuel cell stack, and include a fuel supply path, a fuel discharge path, an oxidant supply path, Each of the oxidizing agent discharge paths is configured (for example, Japanese Patent Laid-Open No. 9-92308).

  When fuel gas such as reformed gas is supplied to the fuel supply port of the fuel cell stack, the fuel gas is distributed and supplied to the fuel supply manifold of each battery plate while passing through the fuel supply path, and from the fuel supply manifold. Each is supplied to a fuel flow path. Similarly, when an oxidant gas such as air is supplied to the oxidant supply path of the fuel cell stack, the oxidant gas is distributed to the oxidant supply manifold of each battery plate while passing through the oxidant supply path. And supplied from the oxidant supply manifold to the oxidant flow path.

  The fuel gas and the oxidant gas distributed and supplied to each battery plate cause an electrochemical reaction through the solid polymer electrolyte membrane to generate an electromotive force. These electromotive forces are collected and taken out from the fuel cell stack, converted into desired power by a power converter such as a DC / AC inverter, and used.

The unreacted fuel gas in each cell plate is discharged to the fuel discharge manifold and discharged to the outside through a fuel discharge path communicating in the stacking direction of the fuel cell stack. The discharged unreacted fuel gas is guided to the reformer burner of the fuel reformer and burned. On the other hand, the oxidant gas that has not reacted in each battery plate is discharged to the oxidant discharge manifold, and is discharged to the outside through an oxidant discharge path communicating in the stacking direction of the fuel cell stack.
Japanese Unexamined Patent Publication No. 09-092308 JP-A-11-354142 JP 2001-143740 A JP 2001-202984 A

  In the conventional solid polymer fuel cell as described above, in order to keep the solid polymer electrolyte membrane in a wet state, the reaction gas is humidified in a water tank provided in the fuel cell system, and is then used as a humidified reaction gas. Supplied to the fuel cell stack. However, when water in the humidified reaction gas is condensed, condensed water is generated, and if this condensed water adheres to the reaction gas flow path of the battery plate, there is a problem that the flow of the reaction gas is hindered and power generation performance is reduced. It was. In the case of a battery plate having a conventional structure as shown in FIG. 2, the reaction gas discharge port B (reaction gas discharge channel) of the battery plate A is located at the outlet of the reaction gas channel C. Condensed water D accumulated in the reaction gas, and the reaction gas channel outlet was narrowed, resulting in a situation where the flow of the reaction gas was hindered.

  The present invention has been made to cope with such a conventional situation, and provides a polymer electrolyte fuel cell in which the flow of the reaction gas is not inhibited by the condensed water accumulated in the reaction gas discharge port of the battery plate. With the goal.

  The means of the present invention for achieving the above-described object includes a unit cell comprising a fuel electrode on one surface of an electrolyte membrane and an oxidant electrode on the other surface, as described in claim 1. In a fuel cell in which a fuel cell stack is formed by stacking a large number in a plane direction perpendicular to a horizontal plane via a plate, a reaction fluid supply manifold that supplies at least one reaction fluid of fuel or oxidant, and the reaction A reaction fluid discharge manifold for discharging the reaction fluid; a cooling medium supply manifold for supplying a cooling medium for cooling the fuel cell stack; and a cooling medium supply manifold. A cooling medium discharge manifold provided at a point-symmetrical position to discharge the cooling medium, and the reaction fluid discharge manifold With the cross-sectional area is larger than the cross-sectional area of the coolant discharge manifold, it is characterized in that is formed extending downward from the reaction fluid flow path outlet of the cell plate.

  Further, as described in claim 2, in the fuel cell according to claim 1, the reaction fluid discharge manifold is formed such that a dimension in a vertical direction is larger than a dimension in a horizontal direction. .

  As described above, according to the present invention, in the fuel cell stack of the polymer electrolyte fuel cell, the reaction gas discharge manifold provided on the battery plate is formed to extend downward from the reaction gas channel outlet and below the reaction gas channel outlet. Since the discharge port leading to the outside of the fuel cell stack is provided, the condensed water generated in the vicinity of the reaction gas channel outlet can be moved downward along the reaction gas discharge manifold and stored at the lower end of the discharge port. Since this discharge port is located below the reaction gas channel outlet, the channel outlet is not narrowed by the condensed water. Thereby, the flow of the reaction gas is not hindered, and the effect of maintaining the power generation performance satisfactorily is achieved. Especially when the reaction gas flow path of the battery plate is meandering in the horizontal direction, the reaction gas outlet is connected to the upper part of the reaction gas flow path when flowing from the bottom to the top of the battery plate. The battery plate can be installed while effectively utilizing the space of the battery plate below the gas flow path outlet.

  Next, an embodiment of a polymer electrolyte fuel cell according to the present invention (when the oxidant manifold is located on the side) will be described with reference to the accompanying drawings.

  In FIG. 1, reference numeral 1 denotes a battery plate, which is formed in a bent shape in which an oxidant flow path 2 composed of a plurality of concave grooves arranged in parallel on one side is meandering in the horizontal direction, and its lower end is a flow path inlet 2a and upper end. Is the channel outlet 2b. A concave groove-like oxidant supply manifold 3 is formed in a vertical direction on one side of the battery plate 1, and a supply port 3 a is provided through the battery plate 1 at an upper part thereof. The reaction gas supply manifold 3 communicates with the channel inlet 2a of the oxidant channel 2 at the lower part. A concave groove-like oxidant discharge manifold 4 is formed in the vertical direction on the other side of the battery plate 1, and a discharge port 4 a is provided through the battery plate 1 at a lower portion thereof. The oxidant discharge manifold 4 communicates with the channel outlet 2b of the oxidant channel 2 at the top.

  The supply port 3a of the oxidant supply manifold 3 and the discharge port 4a of the oxidant discharge manifold 4 communicate with each other in the stacking direction of the fuel cell stack to form an oxidant supply path and an oxidant discharge path, respectively. As a result, when the humidified oxidant gas is supplied from the end of the fuel cell stack to the oxidant supply path, the humidified oxidant gas passes through the oxidant supply path to the oxidant supply manifold 3 of each battery plate 1. The oxidant gas that has been distributed and unreacted is discharged to the oxidant discharge manifold 4, passes through the oxidant discharge passage, and is discharged to the outside as exhaust gas from the end of the fuel cell stack.

  A fuel discharge port 5 and a cooling water supply port 6 are formed through the lower part of the battery plate 1, and a fuel supply port 7 and a cooling water discharge port 8 are formed through the upper part of the battery plate 1. . These communicate with each other in the stacking direction of the fuel cell stack to constitute a fuel discharge path, a cooling water supply path, a fuel supply path, and a cooling water discharge path. Although not shown, a fuel flow path is formed on the surface of the battery plate 1 opposite to the oxidant flow path 2 surface, and a fuel discharge manifold related to the fuel discharge port 5 and a fuel supply port 7 are related. A fuel supply manifold is provided. A cooling plate is interposed in the fuel cell stack. The cooling plate has a cooling water discharge manifold related to the cooling water discharge port 8 and a cooling water supply manifold related to the cooling water supply port 6. And are provided.

  The humidified oxidant gas distributed and supplied to the oxidant supply manifold 3 of the battery plate 1 flows into the oxidant flow path 2 from the flow path inlet 2a at the lower end, flows while meandering horizontally, and flows at the upper end. It reaches the road exit 2b. The surface of the oxidant flow path 2 of the battery plate 1 is surface bonded to the cathode of the solid polymer electrolyte membrane as described above, and the opposite fuel flow path surface is surface bonded to the anode. The fuel gas distributed and supplied from the fuel supply path flows through the fuel supply passage through the fuel supply manifold. In this way, the fuel gas and the oxidant gas are supplied to the battery plate 1, and an electrochemical reaction occurs through the solid polymer electrolyte membrane to generate DC power. During this power generation, the humidified oxidant gas flowing through the oxidant flow channel 2 often condenses water in the vicinity of the flow channel outlet 2b to generate condensed water.

  The condensed water 9 generated by the condensation moves downward along the oxidant discharge manifold 4 from the vicinity of the flow path outlet 2b and accumulates at the lower end of the discharge port 4a. Even if the condensed water 9 accumulates at the lower end of the discharge port 4a, the discharge port 4a is positioned below the oxidant flow channel outlet 2b, so that the flow channel outlet 2b is not narrowed by the condensed water 9. . Therefore, the flow of the oxidant gas flowing through the oxidant flow path 2 is not hindered, and the power generation performance can be kept good.

  The oxidant gas that has not yet reacted in the battery plate 1 is discharged into the oxidant discharge manifold 4 from the flow path outlet 2b as described above. And it is discharged | emitted outside from the edge part of a fuel cell stack through the discharge port 4a (oxidant discharge path). When the unreacted oxidant gas passes through the exhaust port 4a, a large amount of condensed water stays in the lower portion of the discharge port 4a for a long time in order to quickly remove the condensed water 9 accumulated in the lower portion of the discharge port 4a. Not to do. Accordingly, the flow of the unreacted oxidant gas is also smoothly discharged outside the fuel cell stack through the oxidant discharge path as described above without being inhibited by the condensed water 9.

  By the way, a part of the oxidant discharge manifold 4 can be used to penetrate the tie rod 10 for tightening the fuel cell stack. At this time, a gap through which gas flows is provided between the tie rod 10 and the oxidant discharge manifold 4. By constricting the gas flow through this gap, the flow velocity can be increased, and the condensed water 9 accumulated in the lower portion of the discharge port 4a can be eliminated in a short time.

  In the above embodiment, the case where the oxidant manifold of the battery plate is positioned in the lateral direction has been described. However, the same effect can be obtained when the fuel manifold of the battery plate is positioned in the lateral direction. is there. In short, the present invention can be similarly applied regardless of whether the reaction gas is an oxidant gas or a fuel gas.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a solid polymer fuel cell according to the present invention, and is a front view of an oxidant flow path surface side of a battery plate. It is a front view by the side of the oxidant channel surface side of the battery plate in the conventional polymer electrolyte fuel cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery plate 2 ... Oxidant channel 2a ... Channel inlet 2b ... Channel outlet 3 ... Oxidant supply manifold 3a ... Supply port 4 ... Oxidant discharge manifold 4a ... Discharge port 5 ... Fuel discharge port 6 ... Cooling water supply Port 7 ... Fuel supply port 8 ... Cooling water discharge port 9 ... Condensed water 10 ... Tie rod

Claims (2)

A fuel cell stack is formed by laminating a number of unit cells, each of which has a fuel electrode on one side of the electrolyte membrane and an oxidant electrode on the other side, in the plane direction perpendicular to the horizontal plane via the battery plate. In the fuel cell
A reaction fluid supply manifold that supplies at least one reaction fluid of fuel or oxidant; a reaction fluid discharge manifold that is provided at a point-symmetrical position with respect to the reaction fluid supply manifold and that discharges the reaction fluid; and the fuel A cooling medium supply manifold that supplies a cooling medium for cooling the battery stack, and a cooling medium discharge manifold that is provided at a point-symmetrical position with respect to the cooling medium supply manifold and discharges the cooling medium,
The fuel cell is characterized in that the reaction fluid discharge manifold is formed to have a cross-sectional area larger than a cross-sectional area of the cooling medium discharge manifold, and extends downward from a reaction fluid channel outlet of the battery plate. . The fuel cell according to claim 1, wherein
The fuel cell according to claim 1, wherein the reaction fluid discharge manifold has a vertical dimension larger than a horizontal dimension.

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