JP2019109977A - Piping structure for fuel cell system - Google Patents

Abstract

To provide a piping structure for a fuel cell system capable of smoothly discharging production water from a hydrogen gas discharge pipe by preventing freezing of the production water which is produced during power generation of a fuel cell.SOLUTION: A piping structure 10 for a fuel cell system 1 comprising a fuel cell to which a hydrogen gas and air are supplied comprises: an air discharge pipe 12 for discharging air discharged from the fuel cell 2 to the outside of the fuel cell system 1; and a hydrogen gas discharge pipe 14 (14b) which is connected to the air discharge pipe 12 and in which production water that is produced during power generation of a fuel cell 2 is circulated together with at least a portion of the hydrogen gas discharged from the fuel cell. A guide plate 20 is formed while extending into the hydrogen gas discharge pipe 14b from a confluence part A inside of the air discharge pipe 12 in which the production water and the discharged air are confluent in such a manner that a portion of air flowing in the air discharge pipe 12 is guided to the hydrogen gas discharge pipe 14b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a piping structure of a fuel cell system, and more particularly to a piping structure of a fuel cell system for discharging generated water generated at the time of power generation of the fuel cell to the outside of the fuel cell system.

  BACKGROUND ART Conventionally, a fuel cell system supplies a fuel gas containing hydrogen gas and air containing oxygen to a fuel cell, for example, and generates a polymer electrolyte fuel cell (hereinafter referred to as a fuel) generating electricity by an electrochemical reaction of hydrogen and oxygen. It is equipped with a battery). At the time of power generation of the fuel cell, water is generated by an electrical reaction. It is necessary to discharge the generated water, as it will inhibit the electrochemical reaction if it is retained inside.

  As a piping structure of this kind of fuel cell system, for example, in Patent Document 1, in a fuel cell system to which hydrogen gas and air are supplied, a hydrogen gas discharge pipe through which hydrogen gas discharged from the fuel cell passes, and hydrogen gas There has been proposed a piping structure of a fuel cell system including an air discharge pipe connected to the discharge pipe.

Unexamined-Japanese-Patent No. 2017-142982

  However, in the piping structure of the fuel cell system, when the hydrogen gas discharge channel is below the freezing point, if the droplets of the product water discharged together with the hydrogen gas adhere to the hydrogen gas discharge channel, the product water is generated. May freeze. As a result, the hydrogen gas discharge passage may be blocked after a long time operation, which may inhibit the stable operation of the fuel cell.

  The present invention has been made in view of such problems, and can prevent freezing of generated water generated at the time of power generation of a fuel cell, and can smoothly discharge generated water from a hydrogen gas discharge pipe, An object of the present invention is to provide a piping structure of a fuel cell system capable of stably operating a fuel cell.

  In order to achieve the above object, the piping structure of a fuel cell system according to the present invention is a piping structure of a fuel cell system provided with a fuel cell to which hydrogen gas and air containing oxygen gas are supplied. And an air discharge pipe for discharging the air discharged from the fuel cell system to the outside, and the air discharge pipe connected to the air discharge pipe, and at least the water produced at the time of power generation of the fuel cell is discharged from the fuel cell The generated water and the discharged air are provided such that a part of the air flowing through the air discharge pipe is guided to the hydrogen gas discharge pipe, with the hydrogen gas discharge pipe circulating along with the part of the hydrogen gas A guide plate is formed in the hydrogen gas discharge pipe from a merge portion of the air discharge pipe where the air flow merges.

  According to the piping structure of the fuel cell system of the present invention configured as described above, the generated water generated at the time of power generation of the fuel cell flows through the hydrogen gas discharge pipe toward the air discharge pipe and merges with the air discharge pipe. In the section, a part of the air flowing through the air discharge pipe is guided by the guide plate toward the hydrogen gas discharge pipe. As a result, the generated water flowing near the merging portion is heated by the air discharged from the fuel cell, and the generated water can be prevented from freezing in the hydrogen gas discharge pipe. In addition, since a negative pressure is generated downstream of the guide plate in the merging portion in the air discharge pipe, it is possible to promote the flow of generated water from the hydrogen gas discharging pipe to the merging portion.

  According to the piping structure of the fuel cell system of the present invention, the generated water generated at the time of power generation of the fuel cell is prevented from freezing when passing through the hydrogen gas discharge pipe, and the generated water is discharged smoothly from the fuel cell system This enables stable operation of the fuel cell.

It is a schematic block diagram of a fuel cell system using one embodiment of piping structure of a fuel cell system concerning the present invention. It is principal part sectional drawing which shows the confluence | merging part A of the piping structure containing the gas-liquid separator shown in FIG. (A) is principal part sectional drawing in alignment with the BB line of FIG. 2, (b) is a top view of a guide plate. (A) is an essential part sectional view showing an analysis result of temperature distribution of a fuel cell system according to a comparative example, and (b) is an essential part sectional view showing an analysis result of temperature distribution of a fuel cell system according to an example is there. It is sectional drawing along the EE line of FIG.4 (b), (a) is a figure which showed the analysis result of flow velocity distribution, (b) is a sectional view showing the analysis result of pressure distribution It is. It is the graph which showed the subfreezing time of the fuel cell system which concerns on an Example, and the fuel cell system which concerns on a comparative example.

  Hereinafter, an embodiment of a piping structure of a fuel cell system according to the present invention will be described in detail based on the drawings. FIG. 1 is a schematic configuration view of a fuel cell system using a piping structure of a fuel cell system according to the present embodiment.

  In FIG. 1, a fuel cell system 1 is provided with a solid polymer fuel cell 2 which is supplied with hydrogen gas and air and generates electricity by an electrochemical reaction of oxygen and hydrogen. The fuel cell 2 has a stack structure in which a plurality of unit cells 2a, 2a,... Are stacked. The unit cell 2a is a power generation element capable of generating electric power alone, and is fastened by the first and second end plates 3 and 4 in a state of being sandwiched in the stacking direction.

  A pipe structure 10 for supplying air and hydrogen gas to the fuel cell 2 and discharging the air and hydrogen gas after power generation is connected to the first end plate 3 of the fuel cell 2. The piping structure 10 includes an air supply pipe 11 for supplying air to the fuel cell 2 as an air supply side, and an air discharge pipe 12 for discharging air discharged from the fuel cell to the outside of the fuel cell system 1; An air compressor 5 is installed in the middle of the air supply pipe 11. Although not shown, the air supply pipe 11 has an air flow meter, an on-off valve, and the like. The air compressor 5 supplies the fuel cell 2 with the air taken in and compressed from the outside air through the air supply pipe 11.

  The air discharge pipe 12 connected to the fuel cell 2 discharges the air generated after the electrochemical reaction in the fuel cell 2 to the outside of the fuel cell system 1. Although not shown, a pressure control valve or the like is installed in the air discharge pipe 12 as necessary. A hydrogen gas discharge pipe, which will be described later, is connected to the air discharge pipe 12 at a junction A.

  On the first end plate 3 of the fuel cell 2, as a hydrogen gas supply side of the piping structure 10, a hydrogen gas supply pipe 13 for supplying hydrogen gas from the hydrogen tank 6 to the fuel cell 2, and hydrogen discharged from the fuel cell A hydrogen gas discharge pipe 14 for discharging gas together with generated water is connected. Although not shown, an on-off valve, a regulator, a hydrogen supply device, and the like are installed in the hydrogen gas supply pipe 13. The hydrogen supply device is constituted by an injector which is an electromagnetically driven on-off valve.

  The hydrogen gas discharge pipe 14 distributes the generated water generated by the electrochemical reaction at the time of power generation of the fuel cell 2 together with at least a part of the hydrogen gas discharged from the fuel cell 2, and in the present embodiment On the way, a gas-liquid separator 7 is installed. The gas-liquid separator 7 separates hydrogen gas containing generated water into a gas component and a liquid component. Therefore, in the hydrogen gas discharge pipe 14, gas such as hydrogen gas and generated water flow, and the hydrogen gas discharge pipe 14 a located on the upstream side of the gas liquid separator 7 and the generated water separated in the gas liquid separator 7 The flow is composed of a hydrogen gas discharge pipe 14 b located on the downstream side of the gas-liquid separator 7. A drain valve 8 is installed between the gas-liquid separator 7 and the hydrogen gas discharge pipe 14b.

  The gas component separated by the gas-liquid separator 7 is a gas containing hydrogen gas, is circulated to the hydrogen gas supply pipe 13 through the hydrogen gas circulation pipe 15, and is supplied to the fuel cell 2 again. Although not shown, a hydrogen circulation pump is installed in the hydrogen gas circulation pipe 15. The generated water of the liquid component separated by the gas-liquid separator 7 joins the air discharge pipe 12 through the hydrogen gas discharge pipe 14 b on the downstream side and is discharged to the outside of the fuel cell system 1. In the present embodiment, the air discharge pipe 12, the gas-liquid separator 7, and the hydrogen gas discharge pipe 14b are made of resin or rubber.

  In the piping structure 10 of the present embodiment, generated water and a part of the discharged water are discharged to the air discharge pipe 12 for discharging the air (atmosphere) containing the oxygen gas discharged from the fuel cell 2 to the outside of the fuel cell system 1. A hydrogen gas discharge pipe 14a through which hydrogen gas flows is connected. Therefore, the air discharge pipe 12 is formed with a merging portion A in which the air, the generated water and the hydrogen gas merge. The junction A will be described in detail below with reference to FIGS. 2 and 3. 2 is a cross-sectional view of the main part of the merging portion A including the gas-liquid separator 7, FIG. 3 (a) is a cross-sectional view of the main part along line B-B in FIG. 2, FIG. 3 (b) is a guide It is a top view of a board.

  The merging portion A is a portion where part of the generated water from the hydrogen gas discharge pipe 14 a and hydrogen gas merges with the air discharged from the fuel cell, and the merging portion A is formed in the air discharge pipe 12 There is. A guide plate 20 is provided at the merging portion A so as to guide a part of the air flowing through the air discharge pipe 12 to the hydrogen gas discharge pipe 14 (14b).

  Specifically, the guide plate 20 extends from the merging portion A in the air discharge pipe 12 where the generated water and the discharged air merge, to the inside of the hydrogen gas discharge pipe 14b on the downstream side. The pipe diameter of the air discharge pipe 12 is larger than the pipe diameter of the hydrogen gas discharge pipe 14, and the hydrogen gas discharge pipe 14 of small diameter 2 is joined to the air discharge pipe 12 of large diameter 1.

  The guide plate 20 is a plate-like member made of resin or rubber. The guide plate 20 has a width W equal to the inner diameter of the hydrogen gas discharge pipe 14b on the downstream side, one end thereof enters the inside of the hydrogen gas discharge pipe 14b, and the other end is the inside of the air discharge pipe 12 facing It is formed of a plate having a length L which reaches the wall surface. The other end of the guide plate 20 is formed into a circular arc shaped to match the circular arc of the inner wall of the air discharge pipe 12. The guide plate 20 is integrally formed with the hydrogen gas discharge pipe 14b on the downstream side, one end of which is located in the hydrogen gas discharge pipe 14 and the other end of which is discharged from the fuel cell 2 It enters into the air discharge pipe 12 and functions as a baffle.

  The other end of the guide plate 20 enters the flow path of the air discharge pipe 12, but the width W of the guide plate 20 is smaller than the inner diameter of the air discharge pipe 12. In the present embodiment, when the front end of the guide plate 20 contacts the inner wall of the air discharge pipe 12, the communication gaps 21, 21 are formed between the guide plate 20 and the inner wall of the air discharge pipe 12. Thereby, a flow path through which a part of the air discharged from the fuel cell 2 can pass is formed.

  A hydrogen gas discharge pipe 14a on the upstream side is connected to the gas-liquid separator 7 shown in FIG. 2, and a hydrogen gas circulation pipe 15 for circulating gas components to the hydrogen gas supply pipe 13 is connected.

  The operation of the piping structure 10 of the fuel cell system 1 according to the present embodiment configured as described above will be described below. The air taken in through the air supply pipe 11 is compressed by the air compressor 5 and supplied to the fuel cell 2. The hydrogen gas stored in the hydrogen tank 6 is supplied to the fuel cell 2 through the hydrogen gas supply pipe 13. The fuel cell 2 generates electric power by an electrochemical reaction, and generated water is generated inside the fuel cell 2. Then, the air is discharged from the fuel cell 2 through the air discharge pipe 12 to the outside of the fuel cell system 1. The air to be discharged is heated when it is once compressed by the air compressor 5 on the upstream side of the fuel cell 2, and is further heated by the electrochemical reaction in the fuel cell 2.

  The hydrogen gas discharged from the fuel cell 2 after power generation is sent to the gas-liquid separator 7 through the hydrogen gas discharge pipe 14a, and is separated into the gas component containing the hydrogen gas and the produced water. Since the gas component containing hydrogen gas is circulated to the hydrogen gas supply pipe 13 through the hydrogen gas circulation pipe 15, the hydrogen gas can be reused. The product water, which is a liquid component separated by the gas-liquid separator 7, is joined to the air discharge pipe 12 through the hydrogen gas discharge pipe 14b on the downstream side when the drain valve 8 is open, to the outside of the fuel cell system 1. Exhausted. In the hydrogen gas discharge pipe 14b, as shown in FIG. 2, the hydrogen d1 not separated in the gas-liquid separator 7 and the generated water d2 are directed toward the air discharge pipe 12 and intermittently by opening and closing the drain valve 8. Exhausted.

  In the joining portion A of the hydrogen gas discharge pipe 14b to the air discharge pipe 12, a part of the air flowing through the air discharge pipe 12 is guided by the guide plate 20 toward the hydrogen gas discharge pipe 14b as shown by arrow Y1. Specifically, the guided air flows in the upper part of the guide plate 20 in the direction opposite to the flowing direction of the generated water, and is swirled at the end (right end) of the guide plate 20 as shown by arrow Y 2 to guide plate 20. It flows in the same direction as the product water in the lower part of and flows back into the air discharge pipe 12 and merges.

  Thereby, since the air discharged from the fuel cell 2 and heated air heats the generated water flowing through the hydrogen gas discharge pipe 14b, the generated water is generated in the hydrogen gas discharge pipe 14a even under the environment below the freezing point. It is possible to suppress freezing. In particular, in the present embodiment, since the hydrogen d1 and the generated water d2 intermittently flow intermittently from the hydrogen gas discharge pipe 14a by opening and closing the drain valve 8, these heats are small and the air discharge pipe 12, since the gas-liquid separator 7 and the hydrogen gas discharge pipe 14b are made of resin or rubber, they are less likely to transfer the heat from the fuel cell 2 and the gas-liquid separator 7 as compared to metal. However, even in such a case, by providing the above-described guide plate 20, the temperature of the hydrogen gas discharge pipe 14a is raised by air, and it is possible to suppress the generated water from being frozen inside.

  In addition, since the lower region C of the guide plate 20 in the air discharge pipe 12 is in a negative pressure state, the air guided with the generated water easily flows to the air discharge pipe 12 below the guide plate 20. Thereby, the discharge of the generated water in the hydrogen gas discharge pipe 14a can be promoted, and the generated water can be drained smoothly from the hydrogen gas discharge pipe 14a.

  Next, a fuel cell system 1 (pipe structure according to the embodiment) including the pipe structure 10 in which the guide plate 20 of the present embodiment is formed, and a fuel cell system including the conventional pipe structure in which the guide plate is not formed We made an analysis comparing it with the system). This result will be described with reference to FIGS.

  FIG. 4 (a) is a cross-sectional view of the main part showing the analysis result of the temperature distribution of the fuel cell system according to the comparative example, and FIG. 4 (b) is a main point showing the analysis result of the temperature distribution of the fuel cell system according to the embodiment. FIG. 4 (a) and 4 (b) are analysis results after 10 seconds from the discharge of air. FIG. 5 is a cross-sectional view taken along the line E-E of FIG. 4 (b), where (a) is an analysis result of flow velocity distribution, and (b) is an analysis result of pressure distribution It is sectional drawing shown. FIG. 6 is a graph showing the freezing point breakthrough time of the fuel cell system according to the example and the fuel cell system according to the comparative example.

In addition, the gas-liquid separator 7 and the hydrogen gas discharge pipe 14b are respectively PPS resin and nylon resin, and the air discharge pipe 12 set the physical property value supposing EPDM rubber. As analysis conditions, the outside temperature was -30 ° C., and the thermal conductivity was 5 W / m ² -K (no wind). In this state, the flow rate of air was set to 1400 NL / min (constant), and the temperature was set to 60 ° C. (constant). The coolant (FCC) flowing to the gas-liquid separator 7 was 12 L / min (constant), and the temperature was 62 ° C. (constant).

  As shown in FIG. 4A, in the fuel cell system according to the comparative example, the hydrogen gas discharge pipe 14b is located at the D portion on the upstream side of the joining portion A of the air discharge pipe 12 and the hydrogen gas discharge pipe 14b on the downstream side. The inside of was cold. On the other hand, in the portion D on the upstream side of the merging portion A of the fuel cell system of the present embodiment in which the guide plate 20 is formed, the air discharged from the fuel cell 2 by the guide plate 20 as shown in FIG. Was guided into the hydrogen gas discharge pipe 14b and found to be at a higher temperature than that of the comparative example.

  Further, as shown in FIG. 6, in the comparative example, the subfreezing point time is 584 seconds, whereas in the example, it is 59 seconds, and in the example, the guide plate 20 is formed at the joining portion A. It has been confirmed that the temperature rising property is improved.

  Furthermore, as shown in FIGS. 5 (a) and 5 (b), in the embodiment, the air collides with the guide plate 20 on the upstream side of the guide plate 20, and the pressure of the air rises. It was found that the separated flow of air was generated, and the pressure of the air was negative. It can be seen that the negative pressure of the air promotes the flow of generated water in the hydrogen gas discharge pipe 14a.

  As mentioned above, although one embodiment of the present invention was explained in full detail, the present invention is not limited to the above-mentioned embodiment, It is a range which does not deviate from the spirit of the present invention indicated in a claim. It is possible to make design changes.

  For example, in the above-described embodiment, the gas-liquid separator is provided in the middle of the hydrogen gas discharge pipe through which the generated water containing hydrogen gas discharged from the fuel cell flows, but the gas-liquid separator is not necessarily required. The hydrogen gas discharge pipe may be directly connected to the air discharge pipe.

  Further, the shape of the guide plate for guiding a part of the air flowing through the air discharge pipe to the hydrogen gas discharge pipe is not limited to the shape of the embodiment described above, and the air discharged from the fuel cell can be discharged from the hydrogen gas Of course, any shape that can be guided in the direction of the tube may be used. Furthermore, the guide plate may not be in a shape that abuts on the inner wall of the air discharge pipe, but may be formed at an interval.

1: Fuel cell system, 2: Fuel cell, 5: Air compressor, 6: Hydrogen tank, 7: Gas-liquid separator, 8: Drain valve, 10: Piping structure, 11: Air supply pipe, 12: Air exhaust pipe, 13: hydrogen gas supply pipe, 14, 14a, 14b: hydrogen gas discharge pipe, 20: guide plate, 21: communication gap, A: merging portion

Claims (1)

A piping structure of a fuel cell system provided with a fuel cell to which hydrogen gas and air containing oxygen gas are supplied,
An air discharge pipe for discharging the air discharged from the fuel cell to the outside of the fuel cell system;
A hydrogen gas discharge pipe connected to the air discharge pipe, and generated water generated at the time of power generation of the fuel cell flows along with at least a part of hydrogen gas discharged from the fuel cell;
The hydrogen gas is discharged from a merging portion in the air discharge pipe where the generated water and the discharged air merge so as to guide a part of the air flowing through the air discharge pipe to the hydrogen gas discharge pipe. A piping structure of a fuel cell system characterized in that a guide plate is formed inside the tube.

Images