JPH09266003A - Fuel cell power generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized and lightweight fuel cell power generating device by providing a means for measuring the temperature of exhaust gas discharged from an air electrode and the output current value from a fuel cell, and regulating the opening of an exhaust valve on the basis of these values. SOLUTION: In a generating device using a fuel cell 10 having an air electrode and a fuel electrode arranged therein, an exhaust valve 16 is provided on an air discharge passage 14 of exhaust gas discharged from the air electrode. The opening of the exhaust valve 16 is determined by the correlation between the output current value of the fuel cell 10 and the exhaust gas temperature from the air electrode, and controlled by a control means (CPU) 17 so as to impart a water balance condition optimum to the fuel cell 10. This device has a temperature sensor 18 and an ammeter 19 for monitoring the exhaust gas temperature and the current value, and the opening of the exhaust valve 16 is controlled on the basis of the measured values. Thus, the fuel cell 10 can be operated under an optimum water balance condition determined by the correlation of cell temperature and gas flow rate without requiring the supply of water from the outside.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel cell power generator,
In particular, it relates to a power generation device using a polymer solid oxide fuel cell.

[0002]

2. Description of the Related Art In a solid polymer electrolyte fuel cell, an ion conductive film is used as an electrolyte, and hydrogen ions obtained at the fuel electrode of the fuel cell are transferred to the air electrode side in the electrolyte film in the form of protons. Although an electromotive force can be obtained by this, in order to obtain a stable high output, it is important to always keep this electrolyte membrane in an optimally water-containing state.

Therefore, conventionally, fuel gas (hydrogen) or oxidant gas (air or oxygen) is humidified by using a humidifier such as a bubbling device, and the humidified gas is passed through an electrolyte membrane to form an electrolyte. The method of humidifying the membrane is generally adopted.

[0004]

However, in the case of the above-described conventional technique, the fuel cell is inevitably increased in size and weight because it is provided with peripheral equipment such as a humidifier and a water storage tank. This is a fatal disadvantage especially when the vehicle is intended to be mounted.

Further, it is necessary to control the amount of humidification by the humidifier to keep the electrolyte membrane in an optimum wet state, but it is difficult to balance the flow rate of the oxidant gas and the cell temperature which cause the drying of the electrolyte membrane. Such control was difficult.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention provides a fuel cell power generator which is compact and lightweight and is suitable for mounting on a vehicle, by eliminating the need for a humidifier for wetting the polymer solid electrolyte membrane and its peripheral equipment. With the goal.

That is, according to the present invention, in a power generator using a fuel cell in which an air electrode and a fuel electrode are arranged on both sides of a polymer solid electrolyte membrane, exhaust gas containing reaction product water discharged from the air electrode is discharged. Exhaust valve that can be discharged to the outside of the system, temperature measuring means for measuring the temperature of the exhaust gas, current measuring means for measuring the output current value from the fuel cell, and exhaust gas temperature and output measured by these measuring means A control unit that adjusts the opening of the exhaust valve based on a current value.

In the control means, A = correlation data between the output current value of the fuel cell and the amount of water produced inside the fuel cell, B = correlation data between the exhaust gas temperature from the fuel cell air electrode and the saturated water vapor amount, and C. = Correlation data between the exhaust valve opening and the exhaust gas amount passing through the exhaust valve is stored, and A = α · B
The opening of the exhaust valve is adjusted while monitoring the exhaust gas temperature and the output current value so that xC (α is a constant).

[0009]

1 is a schematic diagram showing the structure of a polymer electrolyte fuel cell power generator according to the present invention. A fuel cell 10 is shown as a side view as seen from the air electrode (cathode) side. ing. As is well known, in this fuel cell, a fuel electrode (anode) into which a fuel gas such as hydrogen is introduced is arranged on the side opposite to the air electrode with the polymer solid electrolyte membrane interposed therebetween.

Air as an oxidant gas is introduced into the air electrode from the air introduction portion 11 through the air introduction passage 12 and the fan 13.

As is well known, when hydrogen gas is supplied to the fuel electrode of the fuel cell and air is supplied to the air electrode, hydrogen ions move in the form of protons in the polymer solid electrolyte membrane to cause the cell reaction. Be seen. At this time, in the air electrode, the supplied oxygen reacts with the transferred hydrogen ions and electrons to generate water.

Therefore, in the exhaust gas discharged from the air electrode, in addition to unreacted oxygen, the water produced by the reaction at the air electrode is contained as water vapor.

An exhaust valve 16 is provided in the air exhaust passage 14 for exhausting the exhaust gas, and a certain amount of the exhaust gas from the air electrode is exhausted out of the system according to the opening degree of the exhaust valve 16. .

That is, when the opening of the exhaust valve 16 is narrowed, the reaction product water (steam) permeates the electrolyte membrane due to the concentration difference and moves to the fuel electrode side, and the water that has moved to the fuel electrode side is converted into electricity. The permeated water moves to the air electrode side, and the reciprocating movement of these moisture efficiently and uniformly humidifies the electrolyte membrane.

The opening degree of the exhaust valve 16 is determined by the correlation between the output current value of the fuel cell 10 and the temperature of the exhaust gas from the air electrode, and a control means (CPU) for giving the fuel cell 10 an optimum water balance condition. Controlled by 17.

That is, the following three correlation data are stored in the CPU 17, and the opening of the exhaust valve 16 is monitored while monitoring the exhaust gas temperature and the current value so that A = α · B × C. Are adjusted (see FIG. 2).

A = correlation data between the output current value of the fuel cell and the amount of water produced inside the fuel cell B = correlation data between the temperature of exhaust gas from the fuel cell air electrode and the amount of saturated water vapor C = exhaust valve opening and exhaust Correlation data with the amount of exhaust gas passing through the valve A temperature sensor 18 and an ammeter 19 are provided to monitor the exhaust gas temperature and current value. In the illustrated embodiment, the exhaust gas temperature is monitored by the temperature sensor 18 provided in front of the exhaust valve 16. However, in some cases, the cell temperature may be measured and represented as the exhaust gas temperature.

By controlling the opening of the exhaust valve 16 in this manner, the optimum water balance condition (hatched in FIG. 3) determined by the correlation between the cell temperature and the gas flow rate is required without the need for external water supply. The fuel cell 10 can be operated in the range indicated by.

In the present invention, since the electroosmotic water that wets the electrolyte membrane with the reaction product water in the air electrode of the fuel cell 10 is supplied, the operating temperature of the fuel cell 10 is preferably lower than 100 ° C. . For this purpose, the fuel cell 1
It is preferable to attach a cooling fan 15 to 0 and operate the cooling fan 15 to cool it when the temperature monitored by the temperature sensor 18 exceeds a predetermined value.

[0020]

According to the present invention, the water generated in the air electrode of the fuel cell by power generation is used to humidify the electrolyte membrane, so that external water supply is unnecessary and the humidifier that has been conventionally required. There is no need to install or peripheral equipment.
Therefore, the fuel cell power generator can be significantly reduced in size and weight, and a fuel cell power generator particularly suitable for vehicle mounting can be provided.

Further, since the fuel cell can be operated at a low temperature, the start-up time is shortened and an external heater for raising the temperature to the operating temperature is unnecessary.

During normal operation, the degree of opening of the exhaust valve is adjusted to maintain the optimum water balance condition while monitoring the exhaust gas temperature and the current value, but the current value that changes according to load fluctuations is maintained. Since it is monitored, it is possible to quickly respond to a load change.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a polymer electrolyte fuel cell power generator according to the present invention.

FIG. 2 is a control means (CPU) for controlling an exhaust valve opening degree.
It is explanatory drawing which shows the correlation expression in.

FIG. 3 is a diagram showing an optimum water balance range in the operation of a fuel cell by a correlation between a gas flow rate and a cell temperature.

[Explanation of symbols]

 10 Fuel Cell 11 Air Inlet 12 Air Inlet 13 Fan 14 Air Outlet 15 Cooling Fan 16 Exhaust Valve 17 Control Means (CPU) 18 Temperature Sensor 19 Ammeter

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Goichi Shiraishi 2-19-12 Sotokanda, Chiyoda-ku, Tokyo Equas Research Co., Ltd. N AW Co., Ltd. (72) Inventor Saki Izumisawa 2-19-12 Sotokanda, Chiyoda-ku, Tokyo Equus Research Co., Ltd.

Claims (2)

[Claims] 1. In a power generator using a fuel cell in which an air electrode and a fuel electrode are arranged on both sides of a polymer solid electrolyte membrane, exhaust gas containing reaction product water discharged from the air electrode is discharged to the outside of the system. A dischargeable exhaust valve, a temperature measuring means for measuring the temperature of the exhaust gas, a current measuring means for measuring an output current value from the fuel cell, and an exhaust gas temperature and an output current value measured by these measuring means. And a control unit that adjusts the opening of the exhaust valve based on the fuel cell power generation device. 2. The control means, A = correlation data between the output current value of the fuel cell and the amount of water produced in the fuel cell, B
= Correlation data between exhaust gas temperature from fuel cell air electrode and saturated water vapor amount and C = Correlation data between exhaust valve opening and exhaust gas amount passing through exhaust valve are stored, and A =
The fuel cell power generator according to claim 1, wherein the opening of the exhaust valve is adjusted while monitoring the exhaust gas temperature and the output current value so that α · B × C (α is a constant).