JPS6322423B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-cooled fuel cell equipped with an air supply path dedicated to cooling.

In general, in an air-cooled fuel cell, as shown in FIG. 1, air introduced into a stack via an inlet manifold is divided into a reaction air passage and a cooling air passage, and is then combined at an outlet manifold and discharged. Most of this discharged air is sent to the exhaust passage 2, which has a heat recovery device (not shown), but a portion of it is always returned to the static air passage 2 through the circulation passage 5, and in this case, from the air intake 2, which has a damper. The mixed air of the introduced fresh air and the recirculated air is sent to the stack.

However, in this method, the supply route for reaction air and cooling air is common, making it difficult to control the temperature of the battery, resulting in uneven stack temperatures, and the exhaust air containing acid, which is the electrolyte, resulting in heat generation when exhaust heat is used. There was a problem in that it caused corrosion of the recovery equipment.

In order to improve these problems, the present invention separates the reaction air and cooling-only air supply paths, and makes it possible to introduce a part of the cooling-only air exhaust flow into the reaction air supply path as reaction air. This aims to equalize the electrode reaction and improve the efficiency of the battery system.

An embodiment of the present invention will be described below with reference to FIG.

The battery stack 1 is constructed by stacking unit cells and gas separation plates having reactant gas passages alternately, with intervening cooling plates (none of which are shown) having cooling air passages every few cells. On the opposite side of the battery stack 1 are manifolds 2 and 3 for introducing and discharging reaction air, and manifolds 4 for reacting hydrogen gas.
and 5.

The circulation supply path 6 connecting each of the reaction air manifolds 2 and 3 has an outlet 8 with a damper 7 for discharging a portion of the reacted air to the outside, and a damper 9 for introducing fresh air. The intake port 10 is branched.

The divided manifolds 11 and 12 on the inlet and outlet sides of the cooling air are respectively communicated with the air passages of the stack cooling plates, and the cooling air is supplied to the stack from an inlet pipe 14 having a blower 13, and the cooled exhaust air is The heat is discharged through an exhaust path 16 provided with a heat recovery device 15.

In the present invention, a branch path 18 branching from the exhaust path 16 via a damper 17 is communicated with the reaction air intake port 10, and a part of the exhaust of the cooling air is used as reaction air.

Next, the operation of the battery of the present invention will be explained.

Since the oxygen partial pressure of the reaction air circulating through the reaction air supply path 6 decreases due to the cell reaction, the amount of fresh air that is approximately 1/4 to 1/5 of the circulating flow rate is always supplied to the air intake port 1.
The reacted air is introduced from zero to compensate for the drop in oxygen partial pressure, and a part of the reacted air is led out from the outlet 8. However, when the outside temperature is low, this introduction of outside air causes the temperature on the stack inlet side to be lower than that on the exit side, causing non-uniformity of the battery reaction. The battery temperature changes depending on the load current, but when the load current becomes small, the temperature rise in the stack is suppressed, and in this state, introducing low-temperature outside air will further reduce the temperature on the inlet side.

On the other hand, since the cooling air only cools the stack, the temperature of the exhaust air has risen, but the oxygen partial pressure has not changed at all.

Therefore, under the above-mentioned special conditions, the damper of the branch passage 18 is opened and the damper 9 of the fresh air intake port 10 is closed, and a part of the cooled exhaust air is sent to the inlet side of the reaction air supply passage 6, and the circulating reaction is carried out. Mixed with air and supplied to stack 1. As a result, the temperature of the reaction air introduced into the stack rises, and when the temperature on the inlet side reaches a predetermined temperature, this is detected and the branch passage 18
At the same time, the damper 9 of the intake port 10 is opened.

As described above, a portion of external fresh air or cooled exhaust air is selectively introduced into the reaction air circulation path 6 according to the outside temperature or battery load, thereby equalizing the temperature difference between the stack inlet and outlet sides. In addition, each damper 9 of the air intake port 10 and the discharge port 8 of the reaction air at the time of battery startup
and 7 are closed, the heater 19 is energized and the heated air is sent into the battery by the blower 20. However, in the present invention, the temperature of the cooling exhaust air increases after startup, so this is used as the reaction air. Since it can be used as a heater, heating time can be reduced and power can be saved.

As described above, according to the present invention, the dedicated cooling air path formed separately from the reaction air supply path is provided with a branch pipe that introduces a part of the exhaust flow into the reaction air supply path. The following features are obtained.

(1) Only the required amount of reaction air can be supplied without considering cooling, so loss of electrolyte is reduced and life is improved.

(2) Since the oxygen partial pressure of the cooling air exhaust flow does not change, when the outside temperature is low or the load current is small, a part of this heated exhaust flow can be used as reaction air instead of outside air intake. However, it is possible to equalize the battery temperature and reduce the power consumption of the heater when starting the battery.

(3) Since the cooled exhaust air does not contain acid as an electrolyte, the exhaust heat can be used without corrosion of heat recovery equipment.

(4) The temperature difference between the inlet and outlet sides of the battery stack is reduced, and the electrode reactions are made more uniform, resulting in improved characteristics.

[Brief explanation of the drawing]

FIG. 1 is a route diagram showing an operating device for a conventional battery, and FIG. 2 is a route diagram showing an operating device for a battery according to the present invention. DESCRIPTION OF SYMBOLS 1... Battery stack, 2, 3... Reaction air manifold, 4, 5... Reaction hydrogen gas manifold, 6... Reaction air supply path, 10... Air intake port, 11, 12
...Divided manifold for cooling air, 7, 9, 17... Damper, 15... Heat recovery device, 16... Exhaust path, 18...
Branching road.

Claims (1)

[Scope of Claims] 1. In a fuel cell in which reaction air and cooling air supply paths are formed separately, and the reaction air supply path has an outside air intake port, at least a part of the cooling air exhaust flow is An air-cooled fuel cell characterized by comprising a branch path that introduces reaction air as reaction air into a reaction air supply path. 2. The air cooling according to claim 1, wherein the outside air intake port includes an intake damper, and the cooling air exhaust path includes an exhaust damper, and the branch path branches from the exhaust damper. formula fuel cell. 3. The air-cooled fuel according to claim 2, wherein when one of the exhaust damper of the branch passage and the intake damper of the outside air intake port is in the opening direction, the other is in the closing direction. battery.