JP2008218168A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce gas-flow noise generated when a gas passes through a valve arranged in a passage. <P>SOLUTION: This fuel cell system is provided with: a fuel cell 20 generating power by an electrochemical reaction between a fuel gas and an oxidation gas; a diluter 13 diluting a gas discharged from the fuel cell; a humidifier having first and second passages, and humidifying a gas flowing through the first passage 107 by running a gas supplied to the fuel cell to the first passage 107, and running the gas having passed through the diluter to the second passage 108; a bypass passage 5 introducing a part of the gas having passed through the first passage 107 into the diluter 13; and a bypass valve A4 arranged in the bypass passage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system that generates electric power by an electrochemical reaction between a fuel gas and an oxidizing gas.

  In recent years, fuel cells that generate electricity using an electrochemical reaction between hydrogen and oxygen have attracted attention as energy sources. For example, in a polymer electrolyte fuel cell which is a kind of fuel cell, a solid polymer electrolyte membrane may be referred to as a hydrogen electrode (hereinafter sometimes referred to as “anode”) and an oxygen electrode (hereinafter referred to as “cathode”). ) And a stack (also referred to as “fuel cell stack”) in which cells including MEA (Membrane Electrode Assembly) sandwiched from both sides are stacked. For example, hydrogen gas is supplied to the anode of the MEA as a fuel gas, and air is supplied to the cathode as an oxidizing gas, for example.

  Incidentally, the air used as the oxidizing gas is usually taken in from the outside by a compressor. For this reason, air pressure noise and vibration are generated when the oxidizing gas passes through valves provided at various points in the flow path due to pressure pulsation and other disturbances in the air flow. Therefore, in order to suppress noise of a fuel cell system or a vehicle on which the fuel cell system is mounted, it is desired to reduce such airflow noise.

As a related technique, FIG. 1 of Patent Document 1 discloses a fuel cell system in which a compressor, a silencer, an aftercooler, a filter, a humidifier, and a fuel cell are arranged in this order along the air flow path. Yes. Patent Document 2 discloses a fuel cell humidification system in which a muffler is disposed downstream of the humidifier by steam exchange.
JP 2004-185921 A JP 2001-216986 A

However, neither Patent Documents 1 and 2 describe the generation of airflow noise in a valve provided in the flow path of the oxidizing gas and a method for reducing it.
Therefore, an object of the present invention is to reduce airflow noise that is generated when gas passes through a valve provided in a flow path.

  In order to achieve the above object, a fuel cell system according to one aspect of the present invention includes a fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidizing gas, and a diluter that dilutes the gas discharged from the fuel cell. And a humidifier having first and second flow paths, wherein the gas supplied to the fuel cell is circulated through the first flow path, and the gas that has passed through the diluter is passed through the second flow path. A humidifier that humidifies the gas flowing through the first flow path by flowing through the path, a bypass flow path that introduces a portion of the gas that has passed through the first flow path into the diluter, and And a valve provided in the bypass channel.

  By adopting such a configuration, the oxidizing gas rectified by passing through the first flow path passes through the valve, so that airflow noise generated at that time can be reduced. In addition, by disposing a device such as a diluter upstream of the second flow path of the humidifier, the temperature decreases until the oxidizing off gas discharged from the fuel cell is introduced into the humidifier. The humidity becomes relatively high, and the humidifying performance in the humidifier can be improved.

  The fuel cell system may further include a muffler disposed upstream or downstream of the second flow path of the humidifier. Thereby, noise and vibration can be further reduced. In addition, when the muffler is provided upstream of the humidifier, the number of devices arranged in the flow path from the fuel cell to the humidifier increases, so that the humidity of the oxidant off-gas is further reduced during that time, and the humidifying performance in the humidifier Can be further improved.

  According to the present invention, the flow noise generated when the gas passes through the valve is reduced by rectifying the gas in the humidifier, so that the silencing effect in the muffler at the subsequent stage can be enhanced. Accordingly, it is possible to improve the vibration / noise (NV) performance of the fuel cell system and a vehicle equipped with the fuel cell system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same reference number is attached | subjected to the same component and description is abbreviate | omitted.
FIG. 1 is a system diagram showing the configuration of the fuel cell system according to the first embodiment of the present invention. The fuel cell system according to the present embodiment includes an in-vehicle power generation system for fuel cell vehicles, a power generation system for any moving body such as a ship, an aircraft, a train, or a walking robot, and a power generation facility for a building (house, building, etc.). However, in this embodiment, it is for automobiles.

  The fuel cell system shown in FIG. 1 includes a fuel cell 20 in which a plurality of cells including an electrolyte and electrode layers (anode and cathode) disposed on both sides thereof are stacked. The fuel cell 20 generates power by an electrochemical reaction between the oxidizing gas and the fuel gas. In the present embodiment, air is used as the oxidizing gas, and hydrogen gas is used as the fuel gas.

  The fuel cell system includes an oxidizing gas supply system (filter 10 to oxidizing gas introduction path 1 to humidifier 12 to oxidizing gas supply path 2 and flow path 3) that supplies oxidizing gas to the fuel cell 20. An oxidizing off-gas exhaust system (oxidizing off-gas outlet 4 to humidifier 12 to oxidizing off-gas exhaust 6) for discharging the used oxidizing gas (oxidizing off-gas) from the fuel cell 20 and a fuel gas for supplying the fuel gas to the fuel cell 20 A supply system (fuel gas tank 30 and fuel gas supply path 31) and a fuel off-gas discharge system (fuel off-gas outlet path 32 and fuel off-gas discharge path 33) for discharging the used fuel gas (fuel off-gas) from the fuel cell 20 are provided. Is provided.

  A fuel gas tank 30 is connected to the fuel gas supply path 31, and an on-off valve H1, a pressure adjusting valve H2, and an on-off valve H3 are provided in the middle thereof. In addition, a circulation pump H4 is provided in the fuel off-gas outlet path 32. The circulation pump H4 is reused as fuel gas by pumping the fuel off gas toward the fuel gas supply path 31. Further, a fuel offgas discharge passage 33 provided with an on-off valve H5 is connected to the fuel offgas outlet passage 32. When the fuel offgas is not reused, the fuel offgas passes through the fuel offgas discharge passage 33 to the outside. Discharged.

  A filter 10 and a compressor 11 are provided in the oxidizing gas introduction path 1. The oxidizing gas taken in by the compressor 11 through the filter 10 is introduced into the humidifier 12, where it is humidified to an appropriate humidity. The structure and function of the humidifier 12 will be described later.

  The oxidant gas supply path 2 is provided with an on-off valve A1, through which the oxidant gas humidified in the humidifier 12 is introduced into the fuel cell 20. When the oxidizing gas does not need to be humidified, it is supplied directly to the fuel cell 20 through the flow path 3 by closing the on-off valve A1 and opening the on-off valve A2.

  The oxidation off gas lead-out path 4 is provided with a back pressure adjustment valve A3, a diluter 13, and a muffler 14. The oxidizing gas supply path 2 and the oxidizing off gas lead-out path 4 are connected by a bypass flow path 5 provided with a bypass valve (open / close valve) A4.

  Here, when the power generation efficiency in the fuel cell 20 is low, the amount of fuel gas that is not used increases. Therefore, the surplus fuel gas supplied to the anode side may permeate the electrolyte and ooze out to the cathode side. However, it is environmentally undesirable to discharge the oxidizing off gas mixed with such fuel gas to the outside as it is.

  Therefore, the concentration of the fuel gas mixed in the oxidizing off gas is diluted by introducing the oxidizing gas that has passed through the humidifier 12 into the diluter 13 via the bypass channel 5. The bypass valve A4 is controlled to be opened when the power generation efficiency in the fuel cell 20 becomes low.

  The muffler 14 suppresses the generation of noise and vibration by rectifying the oxidizing off gas. The oxidizing off gas that has passed through the muffler 14 is used to humidify the oxidizing gas in the humidifier 12 (see FIG. 2), and is then discharged from the oxidizing off gas discharge path 6 to the outside.

  FIG. 2 is a diagram illustrating the internal structure of the humidifier 12. The casing 100 of the humidifier 12 is provided with an oxidizing gas inlet 101, an oxidizing gas outlet 102, an oxidizing off gas inlet 103, and an oxidizing off gas outlet 104. In addition, a hollow fiber membrane bundle (hollow fiber module) in which a plurality of hollow fiber membranes 105 that desirably allow only water vapor to permeate are bundled is disposed inside the housing 100. Further, the internal space of the housing 100 is partitioned by a partition member 106 into an oxidizing gas channel (dry side channel) 107 and an oxidizing off gas channel (wet side channel) 108.

The oxidizing off gas derived from the fuel cell 20 (FIG. 1) is a high-humidity gas containing water generated during the electrochemical reaction. When this oxidizing off gas is introduced into the wet-side flow path 108 and passed through the inside of the hollow fiber membrane 105, moisture contained in the gas is absorbed by the hollow fiber membrane 105. On the other hand, when the oxidizing gas is introduced into the dry-side flow path 107 and passed outside the hollow fiber membrane 105, the oxidizing gas is humidified by receiving moisture from the hollow fiber membrane.
In FIG. 2, the outer side of the hollow fiber membrane 105 is a dry-side channel and the inner side is a wet-side channel.

Next, features of the fuel cell system according to the present embodiment will be described with reference to FIGS.
FIG. 3 shows a normal arrangement when the diluter 13 and the muffler 14 are provided in the oxidizing off-gas exhaust system. Usually, the diluter 13 and the muffler 14 are arranged on the end side of the oxidizing off-gas discharge system, that is, on the downstream side of the wet-side flow path 108 (FIG. 2) of the humidifier 12. Therefore, the bypass flow path 5 and the bypass valve A4 for introducing the oxidizing gas into the diluter 13 are also provided in the flow paths (the oxidizing gas supply path 2 and the oxidizing off-gas outlet path 4) that connect the humidifier 12 and the fuel cell 20. Arranged outside.

  However, the oxidizing gas that has been taken in by the compressor 11 and whose airflow is turbulent generates airflow noise or vibrates the valve when passing through the valve provided in the flow path. Therefore, in the configuration shown in FIG. 3, it is difficult to suppress noise and vibration.

Here, it is known that a porous material such as the hollow fiber membrane 105 of the humidifier 12 has a rectifying effect on the gas.
Therefore, in the present embodiment, paying attention to the rectifying action, the humidifier 12 is also used as an auxiliary muffler. That is, after passing through the humidifier 12 by disposing components such as various valves that are likely to generate airflow noise and vibration due to airflow disturbance in the flow path connecting the humidifier 12 and the fuel cell 20. Gas passes through the part.

  Specifically, the bypass flow path 5 and the bypass valve A4 are disposed on the downstream side of the dry-side flow path 107 (FIG. 2) of the humidifier 12. Accordingly, the diluter 13 and the muffler 14 are arranged on the upstream side of the wet-side flow path 108 (FIG. 2) of the humidifier 12. Thereby, the oxidizing gas once rectified by passing through the humidifier 12 is introduced into the diluter 13 through the bypass valve A4. As a result, airflow noise and vibration in the bypass valve A4 are reduced.

  Further, by disposing the diluter 13 and the muffler 14 upstream of the wet-side flow path 108 of the humidifier 12, the distance between the fuel cell 20 and the humidifier 12 is increased, and the oxidizing off gas is converted into the humidifier 12. Before being introduced into the diluter 13 and the like. During this time, the temperature of the oxidizing off gas decreases, so that the humidity of the oxidizing off gas becomes relatively high. Alternatively, moisture contained in the oxidizing off gas may condense. As a result, the difference in humidity between the gas humidified in the humidifier 12 (oxidizing gas) and the gas humidified (oxidized off gas) is increased, so that the humidification performance is improved.

  Next, a fuel cell system according to a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the muffler 14 is arranged on the downstream side of the wet-side flow path 108 (FIG. 2) of the humidifier 12 with respect to the configuration shown in FIG. Other configurations are the same as those shown in FIG.

Even in this case, since the oxidizing gas rectified in the humidifier 12 passes through the bypass valve A4, airflow noise and vibration generated at that time can be reduced.
Thus, if the gas after passing through the humidifier 12 can be passed through a valve that is easily affected by the state of the airflow, the arrangement relationship of the humidifier 12, the diluter 13, and the muffler 14 is particularly great. It is not limited.

1 is a diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention. It is a figure which shows the internal structure of the humidifier shown in FIG. It is a figure which shows the arrangement | positioning of a diluter and a muffler for a comparison. It is a figure which shows the structure of the fuel cell system which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Oxidation gas supply path, 4 ... Oxidation off gas lead-out path, 5 ... Bypass flow path, 12 ... Humidifier, 13 ... Diluter, 14 ... Muffler, 20 ... Fuel cell, 107 ... Dry side flow path, 108 ... Wet side Flow path, A4 ... Bypass valve

Claims (2)

A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidizing gas;
A diluter for diluting the gas discharged from the fuel cell;
A humidifier having first and second flow paths, wherein the gas supplied to the fuel cell is circulated through the first flow path, and the gas that has passed through the diluter is passed through the second flow path. A humidifier for humidifying the gas flowing through the first flow path by circulating the first flow path;
A bypass flow path for introducing a part of the gas that has passed through the first flow path into the diluter;
A valve provided in the bypass flow path;
A fuel cell system comprising:   The fuel cell system according to claim 1, further comprising a muffler disposed upstream or downstream of the second flow path of the humidifier.

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