JPS58164156A - Reaction fluid feed passage structure of fuel cell - Google Patents

Abstract

PURPOSE:To unify a reaction speed regardless of a gradual decrease of the effective component ratio toward the outlet from the inlet by shrinking the cross section of a groove formed by a bipolar plate or porous plate with rib and an electrode or airtight plate at a larger rate than the volume decreasing rate due to the reaction of the reaction fluid. CONSTITUTION:The cross section of a fuel passage is shrunk toward the plane direction of a bipolar plate. The decreasing rate of the passage cross section is made larger than that of a partition 16a according to the conventional design concept that the cross section of the fuel passage 4 is reduced in proportion to a decrease of the fuel volume so as to keep the fuel flow speed contant and a partition 16b is provided to gradually increase the flow speed, thereby the reaction speed is unified. Inlet manifolds 17a, 17c and outlet manifolds 17b, 17d are provided in a pair respectively. Since the fuel flow speed is gradually increased toward the outlet from the inlet, the boundary membrane near the electrode surface is made thin, and the average distance between the gas and electrode becomes smaller, thus a decrease of the reaction speed due to the reduction of the hydrogen partial pressure is compensated and a unified reaction is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reactant fluid supply path structure for a fuel cell. In a fuel cell, in order to guide the reaction fluid (oxidant air, hydrogen peroxide, etc., fuel body IA, hydrazine, etc.) into the reaction zone, fuel is supplied to one side and the oxidizer is supplied to the other side. An airtight bipolar plate that also serves as a separator between the two.

Alternatively, a porous perforated plate with a lip to which fuel or oxidizing agent is supplied is used. The fuel for the fuel cell is a mixture containing several natural gases (for example, Ha 8
0%, 00g 2011) is used.

Since only hydrogen is consumed, the partial pressure of hydrogen gas in the fuel gradually decreases as it is transferred from the battery to the outlet. On the other hand, the speed of the cell reaction increases as the partial pressure of hydrogen in the fuel increases or as the flow rate of the m-fuel increases. Therefore, it is necessary to take measures such as correcting the hydrogen partial pressure in the fuel and the fuel flow rate in order to ensure that the cell reaction progresses uniformly between the population and the outlet.

In the conventional bipolar plate wet fuel cell, as shown in Fig. 1g1 and llI2#A, #I structure is adopted in which a fuel electrode 11 air electrode 2 and a bipolar plate 3 are stacked, and the fuel passage 4 is separated by a partition 6. , the fuel is in the Roman manifold) '7M, the outlet v Nifold 7 to the intermediate manifold T'7-
By making the fuel passage 4 have a U-turn structure and making the return passage more sandwiched than the outgoing passage, the area of the fuel passage from the population to the exit can be made smaller, and the flow rate of the reactant gas can be made uniform. Attempts are being made to make this possible.

In this case, the degree of reduction of the height and width is designed to correspond to the volume reduction due to the reaction of the fuel. However, this ll [
If a pulverized fuel containing 100 g of hydrogen is used, a uniform reaction can be obtained, but if a reformed fuel containing a non-reactive gas, such as a gas, is used, the partial pressure of hydrogen in the fuel will increase. As the population decreases, the reaction speed decreases as the population decreases. This is true not only for fuel but also for oxidizers.

Therefore, the present invention aims to make the reaction rate uniform despite the fact that the ratio of active ingredients decreases from the population to the outlet in a fuel cell that uses a reactive fluid containing non-reactive components as a fuel or oxidizer. The purpose of this invention is to provide a reaction fluid supply channel structure that can be used. This purpose is
According to the invention, this is achieved by reducing the cross-sectional area of the confines created from the inlet to the outlet by a factor greater than the rate of volume reduction due to reaction of the reactant fluid.

According to the present invention, the reaction rate If due to a decrease in the ratio of active ingredients
The decrease is compensated for by the increase in flow velocity, making it possible to achieve a more efficient reaction, and the increase in flow path resistance allows a water head to be formed without special parts, resulting in uniform distribution of the reaction fluid and a uniform reaction. effective.

Below, with reference to the drawings, a case where the present invention is implemented in a fuel passage will be described.

FIGS. 3 and 4 show an embodiment of the present invention in which the product of the fuel passages is reduced by 1rrlfi in the horizontal direction of the pipe 3b. #rkJ451 of the fuel passage 4 is reduced by an amount commensurate with the decrease in fuel volume, and the reduction rate of the passage cross-sectional area is made larger than that of the partition 16, which is based on the conventional design concept of keeping the flow velocity constant in the fB class. By providing the partition 16b that gradually increases the reaction rate, the reaction rate can be made uniform. In this case population! Nifold 17a @
170 @ Out! Nihold 17b.

Two 17d are provided each.

5 and 6 show embodiments of the present invention in which the cross-sectional area of the fuel passage 4 is reduced in the thickness direction of the bipolar plate 3. In this case as well, 14 m is a passage with an inclination according to the conventional design concept, and 14 b is a passage with an inclination according to the present invention. As the fuel increases in flow velocity from the population to the exit point, the boundary film near the electrode surface becomes thinner, and as the average distance between the gas and the electrode becomes smaller, the hydrogen partial pressure decreases. Compensates for the decrease in reaction rate and achieves a uniform reaction.

Figure 7 shows the present invention applied to a fuel cell using a perforated plate with lips: 5I! This is an example. In other words, a uniform reaction is achieved by reducing the fuel flow through the holes and the height of 10a by removing one outlet from the fuel passage, and increasing the fuel velocity vertically.砿＠9 is the lip shape when the lip height is reduced at the same rate as the fuel volume reduction rate. 10b
is a porous ridge with an air connection.

Above, from Fig. 83 to Fig. 7, the fuel passage 411ijL
However, it is obvious to those skilled in the art that the same can be applied to the oxidizing agent passage structure 6, so the explanation will be omitted.

FIG. 8 illustrates the flow of fuel from the population to the outlet and the amount of change in each parameter when the present invention is implemented in a 1m fuel cell using a reformed gas consisting of hydrogen gas. By increasing the reduction rate of passage cross-sectional area weight 1IiIB than the reduction rate of fuel volume 111mA, even if the hydrogen partial pressure decreases to 0, the fuel flow rate increases as D and reacts as a result. It is schematically shown that the velocity [g is constant from the inlet to the outlet.

In all examples, the grooves that subdivide the fuel passages are shown in a large size for easy understanding;
In this case, the fuel gas is distributed by a large number of grooves with a pitch of several millimeters.
1ItIL is made.

[Brief explanation of the drawings] Figure J1 is a schematic diagram of the conventional device, Figure 2 is a plan view of the bipolar plate in Figure 1, and Figure 3 is a schematic diagram of the embodiment of the present invention. 4 is a plan view of the bipolar plate in FIG. 3, FIG. 5 is a schematic exploded perspective view of another embodiment of the present invention, and FIG. 6 is a sectional view of the bipolar plate in FIG. The figure is a schematic exploded perspective view of yet another embodiment of the book@beak, #! FIG. 8 is a characteristic diagram for explaining the present invention in detail. Identical or corresponding parts in all figures are given the same reference numerals. 1: fuel electrode, 2: 9 gas electrode, 3: bipolar plate, 4: fuel passage, 5: #forming agent passage, 10a. tob: ribbed perforated plate, 12: separator, 16b:
partition.

Claims (1)

[Claims] 1) In a fuel cell that uses a reactant fluid with non-reactive components, the cross-sectional area of the reactant fluid passage defined by the biborder plate or the perforated plate with lip and the electrode is defined as the population -
A reactant fluid supply channel structure characterized in that the reactant fluid supply channel is reduced in volume from the reactor toward the outlet at a rate greater than the volume reduction rate due to reaction of the reactant fluid.