JP2013247051A - Ventilation method of fuel cell system - Google Patents

Abstract

An object of the present invention is to provide good and reliable ventilation in a box with a simple process.
A ventilation method of a fuel cell system includes a step of detecting a hydrogen concentration in a box by a hydrogen detection sensor, and the hydrogen concentration detected by the hydrogen detection sensor is equal to or higher than a specified concentration. A step of determining whether the hydrogen concentration is equal to or higher than the specified concentration, a step of increasing the flow rate of ventilation air supplied from the branch pipe 44 into the box 36, and And determining that the branch pipe 44 is abnormal when it is determined that the hydrogen concentration is equal to or higher than the specified concentration in a state where the flow rate of the ventilation air is increased.
[Selection] Figure 1

Description

  The present invention relates to a method for ventilating a fuel cell system in which a fuel cell that generates electricity by an electrochemical reaction between an oxidant gas supplied to a cathode electrode and a fuel gas supplied to an anode electrode is housed in a box.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) provided with an anode electrode and a cathode electrode on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched between a pair of separators. Yes.

  In the fuel cell, a fuel gas passage for supplying fuel gas to an anode electrode is usually formed between one separator and the electrolyte membrane / electrode structure, and the other separator and the electrolyte membrane / electrode are formed. An oxidant gas passage for supplying an oxidant gas to the cathode electrode is formed between the structure and the structure. Furthermore, a cooling medium flow path for flowing a cooling medium in the electrode range is formed between the separators constituting each fuel cell and adjacent to each other.

  This type of fuel cell may be housed in a fuel cell box, particularly when mounted on a fuel cell electric vehicle. At that time, a fuel cell chamber for accommodating the fuel cell is formed in the fuel cell box, and a ventilation device for ventilating the fuel cell chamber is used. For example, when the ventilator detects that hydrogen has entered from the hydrogen line of the fuel cell, the ventilator has a function of discharging the hydrogen to the outside of the fuel cell box by a ventilation fan.

  In addition, in-vehicle fuel cells, there are cases where a fuel cell is mounted in a limited space such as under a vehicle body floor or a front box as a fuel cell chamber. For this reason, in the space where the fuel cell is arranged, that is, in the fuel cell room, it is necessary to ventilate similarly to the inside of the fuel cell box.

  Therefore, for example, a fuel cell box ventilation device disclosed in Patent Document 1 is known. As shown in FIG. 4, the fuel cell box ventilator includes a three-way valve 1, a ventilation pipe 2, a ventilation fan 3, a discharge port 4, a hydrogen detection sensor 5, and a control device 6.

  When the hydrogen inside the fuel cell box B is detected by the hydrogen detection sensor 5, the three-way valve 1 changes the air supplied from the supercharger 7 to the fuel cell V in accordance with the detected value. 2 into the fuel cell box B.

JP 2003-132916 A

  By the way, in Patent Document 1 described above, it is necessary to perform a desired power generation reaction in order to continue power generation by the fuel cell V while performing ventilation processing by the fuel cell box ventilation device. For this reason, the opening diameter of the ventilation pipe 2 is set to a considerably small dimension. Therefore, the ventilation pipe 2 is likely to be clogged or blocked due to freezing, and it is difficult to ensure a desired ventilation function.

  An object of the present invention is to solve this kind of problem and to provide a ventilation method of a fuel cell system that can perform ventilation in a box well and reliably by a simple process.

  In the present invention, a fuel cell that generates electricity by an electrochemical reaction of an oxidant gas supplied from an oxidant gas supply system to a cathode electrode and a fuel gas supplied from a fuel gas supply system to an anode electrode is housed in a box. In addition, a branch pipe branched from the oxidant gas supply system and having a smaller flow rate than the pipe of the oxidant gas supply system is opened in the box, while a hydrogen detection sensor is provided in the box. The present invention relates to a ventilation method for a fuel cell system.

  In this ventilation method, a step of detecting a hydrogen concentration in the box by a hydrogen detection sensor, a step of determining whether or not the hydrogen concentration detected by the hydrogen detection sensor is equal to or higher than a specified concentration, and the hydrogen When the concentration is determined to be equal to or higher than the specified concentration, the step of increasing the flow rate of the oxidant gas for ventilation supplied from the branch pipe into the box and the flow rate of the oxidant gas for ventilation were increased. And determining that there is an abnormality in the branch pipe when the hydrogen concentration is determined to be equal to or higher than the specified concentration.

  In this ventilation method, the branch pipe is preferably provided with an orifice for imparting pressure loss to the ventilation oxidant gas.

  In the present invention, when the hydrogen concentration in the box is equal to or higher than the specified concentration, the flow rate of the oxidant gas for ventilation supplied into the box is increased. Here, even after the flow rate of the oxidant gas for ventilation is increased, if the hydrogen concentration in the box is equal to or higher than the specified concentration, it is detected that an abnormality, for example, a blockage has occurred in the branch pipe. Therefore, it is possible to detect an abnormality in the branch pipe and perform ventilation in the box satisfactorily and reliably by a simple process.

1 is a schematic configuration diagram of a fuel cell system to which a ventilation method according to an embodiment of the present invention is applied. It is a flowchart explaining the said ventilation method. It is explanatory drawing which shows the change of the hydrogen concentration by the said ventilation method. It is a schematic explanatory drawing of the fuel cell box ventilation apparatus currently disclosed by patent document 1. FIG.

  As shown in FIG. 1, a fuel cell system 10 to which a ventilation method according to an embodiment of the present invention is applied includes, for example, an in-vehicle fuel cell mounted on a fuel cell vehicle (not shown) such as a fuel cell electric vehicle. Configure the system.

  The fuel cell system 10 includes a fuel cell 14 in which a plurality of power generation cells 12 are stacked (stacked) in a horizontal direction or a gravity direction. In the power generation cell 12, an electrolyte membrane / electrode structure (MEA) 16 is sandwiched between a cathode separator 18 and an anode separator 20. The electrolyte membrane / electrode structure 16 includes, for example, a fluorine-based or hydrocarbon-based solid polymer electrolyte membrane 22, and a cathode electrode 24 and an anode electrode 26 that sandwich the solid polymer electrolyte membrane 22.

  The cathode electrode 24 and the anode electrode 26 are formed of a gas diffusion layer made of carbon paper or the like, and an electrode catalyst formed by uniformly applying porous carbon particles carrying a platinum alloy on the surface of the gas diffusion layer. And having a layer. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 22.

  An oxidant gas passage 28 is formed on the surface of the cathode separator 18 facing the electrolyte membrane / electrode structure 16. A fuel gas passage 30 is formed on the surface of the anode separator 20 facing the electrolyte membrane / electrode structure 16. A cooling medium passage (not shown) is formed between the cathode separator 18 and the anode separator 20 adjacent to each other.

  The fuel cell 14 includes an oxidant gas supply device (oxidant gas supply system) 32 that supplies an oxidant gas, for example, air, to the oxidant gas passage 28, and a fuel gas, for example, hydrogen gas, to the fuel gas passage 30. A fuel gas supply device (fuel gas supply system) 34 to be supplied and a cooling medium supply device (not shown) for supplying the cooling medium to the cooling medium passage are connected. The fuel cell 14 is accommodated in the box 36.

  The oxidant gas supply device 32 includes an air pump 38 that compresses and supplies air from the atmosphere, and the air pump 38 is disposed in an air supply pipe 40. The air supply pipe 40 is provided with a humidifier 42 for exchanging moisture and heat between the supply gas (supply oxidant gas) and the exhaust gas (exhaust oxidant gas). The fuel cell 14 communicates with the oxidant gas passage 28.

  A branch pipe 44 branches from the air supply pipe 40. The branch pipe 44 is located between the air pump 38 and the humidifier 42 and branches from the air supply pipe 40. An orifice 46 is provided in the branch pipe 44, and the flow rate of the branch pipe 44 is set to be smaller than the flow rate of the air supply pipe 40 through the orifice 46. The branch pipe 44 is connected to the lower part of the box 36 and is opened in the box 36.

  The fuel gas supply device 34 includes a hydrogen tank 48 that stores high-pressure hydrogen. The hydrogen tank 48 communicates with the fuel gas passage 30 of the fuel cell 14 via the hydrogen supply pipe 50. An on-off valve 52 is provided in the middle of the hydrogen supply pipe 50.

  The box 36 accommodates the fuel cell 14 and a hydrogen detection sensor 54 for detecting the hydrogen concentration. The hydrogen detection sensor 54 is disposed on the upper surface (top plate) 36 a in the box 36. An exhaust duct 56 is connected to the upper portion of the box 36 in the vicinity of the hydrogen detection sensor 54. The exhaust duct 56 and the branch pipe 44 are arranged at diagonal positions in the box 36. In the box 36, auxiliary equipment for the fuel cell 14 may be accommodated.

  The fuel cell system 10 includes a controller 58. The controller 58 controls the entire fuel cell system 10 and, as will be described later, a function for determining whether or not the hydrogen concentration detected by the hydrogen detection sensor 54 is equal to or higher than a specified concentration, and the branch pipe 44 It has a function to determine whether or not there is an abnormality.

  The operation of the fuel cell system 10 configured as described above will be described below in relation to the ventilation method according to the present embodiment.

  First, during operation of the fuel cell system 10, air is sent to the air supply pipe 40 through the air pump 38 that constitutes the oxidant gas supply device 32. The air is humidified through the humidifier 42 and then is supplied to the cathode electrode 24 by moving along the oxidant gas passage 28 provided in each power generation cell 12 in the fuel cell 14.

  Although used air is exhausted from the oxidant gas passage 28, the used air is sent to the humidifier 42 to humidify the newly supplied air and then exhausted.

  On the other hand, in the fuel gas supply device 34, when the on-off valve 52 is opened, hydrogen gas decompressed by a pressure reducing valve (not shown) is supplied from the hydrogen tank 48 to the hydrogen supply pipe 50. The hydrogen gas is supplied to the anode electrode 26 by moving along the fuel gas passage 30 of each power generation cell 12 of the fuel cell 14.

  The spent hydrogen gas is returned from the fuel gas passage 30 to the hydrogen supply pipe 50 via a hydrogen circulation path (not shown) and supplied again to the fuel cell 14 as fuel gas.

  Therefore, the air supplied to the cathode electrode 24 and the hydrogen gas supplied to the anode electrode 26 react electrochemically to generate power. As described above, the fuel cell system 10 mounted on a fuel cell vehicle (not shown) performs a desired travel by performing a normal operation.

  On the other hand, in the box 36 in which the fuel cell 14 is accommodated, the hydrogen concentration in the box 36 is detected by the hydrogen detection sensor 54. The controller 58 constantly detects and monitors the hydrogen concentration in the box 36 (step S1 in FIG. 2).

  In step S2, it is determined whether or not the hydrogen concentration detected by the hydrogen detection sensor 54 is a specified concentration (concentration threshold), for example, several thousand ppm or more.

  When it is determined that the hydrogen concentration is equal to or higher than the specified concentration (YES in step S2), the process proceeds to step S3. In step S3, the flow rate of the oxidizing gas for ventilation supplied from the branch pipe 44 into the box 36 is increased. Specifically, the rotational speed of the air pump 38 is increased to increase the flow rate of air supplied to the air supply pipe 40. As a result, the flow rate of air diverted to the branch pipe 44 is increased, and the flow rate of ventilation air (ventilating oxidant gas) supplied to the box 36 is increased.

  At this time, as shown in FIG. 3, when the flow rate of the ventilation air supplied to the box 36 is increased, the hydrogen concentration in the box 36 decreases. For this reason, the hydrogen concentration detected by the hydrogen detection sensor 54 is lower than the specified concentration (NO in step S4).

  On the other hand, when it is determined that the hydrogen concentration detected by the hydrogen detection sensor 54 is equal to or higher than the specified concentration regardless of the increase in the air flow rate divided into the branch pipe 44 (YES in step S4). The process proceeds to step S5. That is, the orifice 46 is blocked by freezing, clogging, or the like, and the ventilation air cannot be circulated satisfactorily. Therefore, the controller 58 recognizes that the branch pipe 44 is abnormal.

  In this case, in this embodiment, when the hydrogen concentration in the box 36 is equal to or higher than the specified concentration, the flow rate of the ventilation air supplied into the box 36 is increased. Here, even after the flow rate of the ventilation air is increased, if the hydrogen concentration in the box 36 is equal to or higher than the specified concentration, it is detected that the branch pipe 44 is abnormal, for example, the orifice 46 is blocked. The As a result, it is possible to detect an abnormality of the branch pipe 44 by a simple process and to effectively and reliably perform ventilation in the box 36.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 12 ... Power generation cell 14 ... Fuel cell 16 ... Electrolyte membrane and electrode structure 22 ... Solid polymer electrolyte membrane 24 ... Cathode electrode 26 ... Anode electrode 28 ... Oxidant gas passage 30 ... Fuel gas passage 32 ... Oxidation Agent gas supply device 34 ... Fuel cell gas supply device 36 ... Box 38 ... Air pump 40 ... Air supply piping 44 ... Branch piping 46 ... Orifice 48 ... Hydrogen tank 50 ... Hydrogen supply piping 54 ... Hydrogen detection sensor 58 ... Controller

Claims (2)

A fuel cell that generates electricity by an electrochemical reaction of an oxidant gas supplied from the oxidant gas supply system to the cathode electrode and a fuel gas supplied from the fuel gas supply system to the anode electrode is housed in the box, and A fuel cell system that branches from an oxidant gas supply system, and a branch pipe having a smaller flow rate than the pipe of the oxidant gas supply system is opened in the box, and a hydrogen detection sensor is provided in the box The ventilation method of
Detecting the hydrogen concentration in the box by the hydrogen detection sensor;
Determining whether the hydrogen concentration detected by the hydrogen detection sensor is equal to or higher than a specified concentration;
A step of increasing the flow rate of the oxidizing gas for ventilation supplied from the branch pipe into the box when it is determined that the hydrogen concentration is equal to or higher than the specified concentration;
The step of certifying that there is an abnormality in the branch pipe when it is determined that the hydrogen concentration is equal to or higher than the specified concentration in a state where the flow rate of the oxidizing gas for ventilation is increased;
A method for ventilating a fuel cell system, comprising:   2. The ventilation method according to claim 1, wherein an orifice for imparting pressure loss to the ventilation oxidant gas is disposed in the branch pipe.

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