JPH06119931A - Device of humidifying system for fuel cell - Google Patents

Abstract

PURPOSE:To maintain the water retaining condition of a high-polymer ion exchange film as an electrolyte and facilitate uniform distribution of hydrogen in each stack. CONSTITUTION:A fuel cell humidifying system device has solid high-polymer electrolyte fuel cell stacks 31, 32 split in a plurality of fragments and humidifying devices 36, 37 located upstream of the stackes 31, 32 to humidify the fuel hydrogen, wherein the stacks 31, 32 are connected with the humidifying devices 36, 37, and humidification takes place little by little in the course of the fuel hydrogen being consumed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidifying system device for a fuel cell, which comprises a fuel cell stack of a solid polymer electrolyte fuel cell and a humidifying device.

[0002]

2. Description of the Related Art As is well known, the power generation principle of a solid polymer electrolyte fuel cell is as shown in FIG. The electrode assembly 1 is
As the electrolyte (polymer ion exchange membrane) 2, a fluororesin polymer ion exchange membrane (for example, a fluororesin ion exchange membrane having a sulfonic acid group) is used, and the catalyst electrode is made of, for example, platinum on both sides with this center. (Negative electrode) 3 and catalyst electrode (anode) 4 are attached, and both surfaces thereof are sandwiched and sandwiched by porous carbon electrode (negative electrode) 5 and carbon electrode (anode) 6.

The hydrogen introduced into the fuel cell main body through the flow channel of the separator 7 usually has a hydrogen ion permeability of the polymer ion exchange membrane, which is the electrolyte 2, so that the hydrogen is normally introduced before introduction into the fuel cell. The steam corresponding to the saturated steam partial pressure in the vicinity is contained, that is, humidified before being introduced. Oxygen or air may be humidified for the same reason.

The hydrogen supplied to the electrode assembly 1 is hydrogen-ionized on the catalyst electrode (negative electrode) 3, and the hydrogen ions are H ^{+ in the} electrolyte 2. -Move toward the catalyst electrode (anode) 4 side as xH ₂ O. At this time, since hydrogen ions move from the negative electrode to the anode along with x H ₂ O, the water vapor introduced together with hydrogen gradually permeates to the anode side along the hydrogen flow path direction and approaches the dry gas. I will go.

The hydrogen ions reaching the carbon electrode (anode) 6 react with oxygen similarly introduced into the battery main body as an oxidant to generate water, which is discharged together with unreacted oxygen.
Similarly, unreacted hydrogen that has not been hydrogen-ionized is also discharged from the fuel cell body.

A conventional humidification system device for a solid polymer electrolyte fuel cell is as shown in FIG. This figure shows
An example in which hydrogen as a fuel and oxygen (or air) as an oxidant are humidified and introduced into a fuel cell will be shown. Here, as the humidifying water source, cooling water that has recovered the exhaust heat of the fuel cell and has become hot water is used. Hydrogen and oxygen (or air) introduced into the fuel cell stack 11 contain, that is, are humidified by the humidifying device 12, containing steam having a saturated steam partial pressure near the fuel cell operating temperature. Humidified hydrogen, oxygen (or air)
Is the insertion surface of all electrode assemblies in the fuel cell stack 11.
It is adapted to be distributed to 13 through the channel groove of the separator 14. In addition, 15 in a figure shows a cooling water surface.

[0007]

However, the conventional humidification system device has the following problems.

(1) Since the hydrogen as fuel is humidified only at the inlet for introducing into the fuel cell, the amount of water vapor introduced into the fuel cell is limited to the amount of water vapor corresponding to the saturated water vapor partial pressure at the humidification temperature. I will end up. Therefore, when trying to increase the area of the electrolyte or the area of the electrode assembly, the water vapor that has humidified the hydrogen is H ⁺ ・ In the form of xH ₂ O, it gradually permeates to the oxygen or air side, the water vapor pressure becomes low near the end of the hydrogen flow channel groove, and it approaches a dry gas, and the water retention state of the polymer ion exchange membrane that is the electrolyte can be maintained. Disappear.

(2) Since hydrogen, which is a fuel, is distributed and supplied to all electrode assemblies at one time, the gas flow rate of hydrogen supplied to the electrode assemblies is extremely low, and when the number of electrode assemblies is large, the flow rate distribution is performed. Is extremely difficult to equalize.

The present invention has been made in consideration of such circumstances, and it is possible to maintain the water-retaining state of the polymer ion-exchange membrane as the electrolyte and increase the gas flow rate of hydrogen supplied to the electrode assembly to produce hydrogen. An object of the present invention is to provide a humidification system device for a fuel cell, which can easily perform uniform distribution in each stack.

[0011]

The present invention has a solid polymer electrolyte fuel cell stack divided into a plurality of parts, and a humidifying device provided on the upstream side of each stack for humidifying fuel hydrogen. A humidification system device for a fuel cell, wherein each stack and a plurality of humidification devices are connected to successively humidify the fuel hydrogen as it is consumed.

FIG. 3 is a schematic diagram of a humidification system device for a fuel cell according to the present invention. Reference numerals 21, 22, and 23 in the figure denote fuel cell stacks divided into a plurality of fuel cells. The fuel hydrogen introduced into each of the fuel cell stacks 21 to 23 is humidified on the upstream side so that the fuel hydrogen can be sequentially humidified. A device 24 and humidifying devices (intermediate) 25 and 26 are arranged respectively. Oxygen or air as an oxidant may be humidified if necessary. Here, as the wet water source of the humidifiers 24 to 26, it is conceivable to use the exhaust cooling water after cooling all the stacks that sequentially use the exhaust cooling water of each stack.

[0013]

In the above structure, the stack of the solid polymer electrolyte fuel cell is divided or connected in series, and the fuel is introduced into each stack while successively humidifying hydrogen,

(1) A polymer ion membrane, which is an electrolyte, is replaced with H ⁺ ・
It becomes possible to always supplement the water vapor content that permeates in the form of xH ₂ O, and the water vapor pressure can be secured near the end of the flow channel groove on the hydrogen separator. That is, the water-retaining state of the polymer ion-exchange membrane, which is the electrolyte, can be maintained.

(2) The flow rate of the gas distributed and supplied to each electrode assembly can be made large because the number of distributions is small, and hydrogen can be easily distributed evenly in each stack.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In each of the examples, an example is shown in which a solid polymer electrolyte fuel cell stack is divided or connected in series with a hydrogen line as a fuel, and a humidifier is provided upstream of each stack. (Example 1)

Referring to FIG. In the figure, 31 indicates a first fuel cell stack and 32 indicates a second fuel cell stack. These fuel cell stacks have a plurality of stacked separators 33, 34 indicates an electrode assembly insertion surface, and 35 indicates a cooling water surface. A humidifier 36 is arranged upstream of the first fuel cell stack 31, and an intermediate humidifier 37 is arranged upstream of the second fuel cell stack 32.

In the humidifying system device for a fuel cell having such a structure, the hydrogen and oxygen (or air) supplied to the first fuel cell stack 31 are supplied to the second fuel cell stack 32.
The discharged wet water is humidified and introduced into the first fuel cell stack 31. Furthermore, the remaining hydrogen and oxygen (or air) discharged from the first fuel cell stack 31 are humidified by the cooling water that has become wet water discharged from the first fuel cell stack 31, and the second fuel is discharged. It is introduced into the battery stack 32. (Embodiment 2) Referring to FIG. However, the same members as those in FIG. 4 are denoted by the same reference numerals and the description thereof will be omitted.

Hydrogen and oxygen (or air) supplied to the first fuel cell stack 31 are used as the first fuel cell stack 31.
Also, the second fuel cell stack 32 is cooled and humidified by the discharged cooling water to be introduced into the first fuel cell stack 31. Furthermore, the remaining hydrogen and oxygen (or air) discharged from the first fuel cell stack 31 is
The fuel cell stack 31 and the second fuel cell stack 32 are cooled and discharged by the humidified cooling water,
It is introduced into the second fuel cell stack 32. (Embodiment 3) Referring to FIG. However, the same members as those in FIG. 4 are denoted by the same reference numerals and the description thereof will be omitted. The third embodiment is summarized in that oxygen or air as an oxidant in FIG. 4 is branched and supplied to each stack from the beginning. (Embodiment 4) Referring to FIG. However, the same members as those in FIG. 4 are denoted by the same reference numerals and the description thereof will be omitted. The fourth embodiment is summarized in that oxygen or air as an oxidant in FIG. 5 is branched and supplied to each stack from the beginning.

As described above, according to the above-described embodiment, the first fuel cell stack 31 and the second fuel cell stack 32 are divided,
Alternatively, the following advantages can be obtained by connecting in series and providing the humidifying device 36 and the intermediate humidifying device 37 on the upstream side of each stack of the hydrogen line as fuel.

(1) It is possible to supplement each of the humidifiers 36 with water vapor that permeates the polymer ion exchange membrane as the electrolyte and moves to the oxygen or air side. Therefore, the polymer ion-exchange membrane can be maintained in a sufficiently water-retentive state over the entire area along the hydrogen flow channel on the separator.

(2) Since the number of distributions to each electrode assembly is small, it is possible to obtain a large hydrogen gas flux in the hydrogen flow passage groove on the separator. Therefore, it becomes easy to distribute hydrogen evenly to the electrode assembly in each stack.

[0023]

As described above in detail, according to the present invention,
A humidification system device for fuel cells that can maintain the water-retaining state of the polymer ion-exchange membrane, which is the electrolyte, and increase the gas flow rate of hydrogen supplied to the electrode assembly to facilitate even distribution of hydrogen in each stack. Can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a power generation principle of a solid polymer electrolyte fuel cell.

FIG. 2 is an explanatory diagram of a conventional fuel cell humidification system device.

FIG. 3 is a schematic configuration diagram of a humidification system device for a fuel cell according to the present invention.

FIG. 4 is an explanatory diagram of a humidification system device for a fuel cell according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a humidification system device for a fuel cell according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a humidification system device for a fuel cell according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of a humidification system device for a fuel cell according to a fourth embodiment of the present invention.

[Explanation of symbols]

31 ... First fuel cell stack, 32 ... Second fuel cell stack, 33 ... Separator,
36 ... Humidifier, 37 ... Intermediate humidifier.

Claims (1)

[Claims] 1. A solid polymer electrolyte fuel cell stack divided into a plurality of parts, and provided on the upstream side of each stack,
A humidifier for humidifying fuel hydrogen, wherein the stacks and a plurality of humidifiers are connected to each other to sequentially humidify the fuel hydrogen while it is being consumed. System unit.