JP2008251330A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery having a small air flow rate distribution in a fuel cell stack and a small temperature distribution and cell reaction distribution.
A rectangular parallelepiped fuel cell stack having an air inlet formed on an upper surface and an air outlet formed on a lower surface, and connected to the air inlet, the upper surface of the fuel cell stack from one side of the fuel cell stack. The air supply duct that supplies air to the air inlet and the air discharge duct is connected to the air discharge port, and the air discharged from the fuel cell stack is substantially parallel to the lower surface of the fuel cell. A fuel cell system comprising an air exhaust duct for exhausting to the other side, wherein a baffle for reducing a flow velocity distribution of air discharged from the air discharge port is provided below the fuel cell stack.
[Selection] Figure 2

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system characterized by a gas supply and discharge mechanism in a normal pressure operation type fuel cell.

In a fuel cell, a unit fuel cell in which a fuel electrode and an oxygen electrode are arranged via an electrolyte membrane is electrically connected in series via a bipolar plate, and a plurality of units are connected in series or in series-parallel. The fuel cell stack is formed.
Fuel such as hydrogen is supplied to the fuel electrode of the fuel cell stack by the fuel supply means. In addition, an air supply duct that supplies air from an air supply fan that supplies air to the oxygen electrode of the fuel cell stack is combined with an air exhaust duct that discharges air containing water generated by the fuel cell reaction. Yes.

The pressurization operation type that supplies pressurized air to the fuel cell stack has a feature that the output of the fuel cell can be increased, but an air pressurizing means is required. .
However, even when a turbocharger that operates with exhaust gas from a reformer or the like is available, the power generated by the fuel cell is self-consumed. The pressure type is not effective because it has low energy efficiency.
In view of this, the present applicant has proposed a fuel cell system that is of the normal pressure operation type, and in which the air introduced by the air supply fan is uniformly supplied to the fuel cell stack via the air introduction duct. (For example, refer to Patent Document 1).

FIG. 5 is a diagram illustrating an example of a normal-pressure operating fuel cell system.
FIG. 5A shows a perspective view, and FIG. 5B is a plan view for explaining the flow of air.
An air supply duct 54 is coupled to the fuel cell stack 100 of the fuel cell system 1, and the supply duct 54 is provided with an air fan 122 that supplies air.
The air taken in by the air fan is introduced from the air introduction path 123 and diffused by the diffusion member 123m for diffusing the air, and then flows through the air supply duct 54 and sent to the fuel cell stack 100. The air sent from the upper surface of the fuel cell stack 100 to the oxygen electrode is discharged from the lower part of the fuel cell stack 100 and sent to a condenser or the like (not shown) to generate water generated by the fuel cell reaction, and the fuel cell. The water supplied to the oxygen electrode is separated and discharged to the outside. And the water collect | recovered with the condenser etc. is utilized as water which humidifies an electrolyte membrane.
When there is sufficient space at the bottom of the fuel cell stack 100, the distribution of the air flow velocity in the fuel cell stack is unlikely to occur, but when the fuel cell system is installed inside an automobile or the like, The installation environment may affect the performance of the fuel cell system.

FIG. 6 is a diagram for explaining another example of the fuel cell system.
6A shows a perspective view, FIG. 6B is a plan view for explaining the flow of air, and FIG. 6C is a side view for explaining the flow of air during installation.
An air supply duct 54 is connected to the fuel cell stack 100 provided in the fuel cell system 1 and is sent from the air fan 122 to the fuel cell stack 100 through a diffusion member 123 m provided in the air introduction path 123. Air sent from the upper surface of the fuel cell stack 100 to the oxygen electrode is discharged from the lower part of the fuel cell stack 100 through the air exhaust duct 124.
However, when installing in a place where the installation space 130 is limited, such as the floor portion of an automobile, the flow direction is changed by the air supply duct and the air exhaust duct, so the upper and lower portions of the fuel cell stack A distribution (deviation) occurs for the differential pressure. That is, as the pressure difference becomes larger as it approaches the outlet side B than the fan side A, it has become clear that the phenomenon that the air flow rate inside the fuel cell stack is faster on the fan side and slower on the outlet side occurs. .
In the fuel cell stack, if the air flow velocity distribution occurs, the temperature distribution and power generation reaction distribution will occur in each unit fuel cell that constitutes the fuel cell stack. was there.
JP 2004-424746 A

Since the present invention has a restriction in the height direction of the installation space, even if the air discharge duct for discharging air from the fuel cell stack is provided in a direction perpendicular to the discharge port of the fuel cell stack, the fuel cell An object of the present invention is to provide a fuel cell system in which the distribution of flow velocity in the stack is reduced.
Another object of the present invention is to prevent the supply of air to the oxygen electrode side of the fuel cell from becoming uneven, resulting in uneven heat distribution due to reaction heat, and damage to the fuel cell. is there.

The present invention includes a rectangular parallelepiped fuel cell stack having an air inlet formed on an upper surface and an air outlet formed on a lower surface, and an upper surface of the fuel cell stack connected to the air inlet from one of the fuel cell stacks. The air supply duct that supplies air to the air inlet and the air discharge duct is connected to the air discharge port, and the air discharged from the fuel cell stack is substantially parallel to the lower surface of the fuel cell. A fuel cell system including an air exhaust duct for exhausting to the other side, wherein a baffle for reducing a flow velocity distribution of air discharged from the air discharge port is installed below the fuel cell stack; is there.
The baffle is the fuel cell system, wherein the baffle is disposed so as to be inclined downward from a lower end opposite to an air introduction direction of the fuel cell stack toward a center of the fuel cell stack.
The fuel cell system comprising air supply means for supplying normal pressure air to the fuel cell stack through the air supply duct.

According to the configuration of the first aspect of the present invention, the air exhaust port of the fuel cell stack is provided with the baffle extending obliquely from the end of the air exhaust duct on the downstream side of the air exhaust duct toward the center. Since the flow path in the exhaust duct is restricted, the flow velocity inside the fuel cell stack is made uniform regardless of the distance to the inflow portion by reducing the distribution (differential pressure) of the differential pressure between the upper and lower parts of the fuel cell stack. can do.
According to the second aspect of the present invention, the distribution of the differential pressure inside the fuel cell can be made uniform even when the distance from the wall surface of the discharge duct is shortened, so that an efficient and stable fuel cell system is provided. It becomes possible to do.
Moreover, according to the structure of Claim 3, the influence of the disturbance of the differential pressure distribution in the fuel cell operated by atmospheric pressure air can be prevented, and a fuel cell system excellent in power generation efficiency and battery characteristics can be provided. .

  The present invention is a part in which the differential pressure is increased by providing a baffle in the air discharge path of the distribution of the air flow velocity in the fuel cell stack even when the installation location is limited as in a fuel cell for an automobile. The present inventors have found that it is possible to provide a fuel cell system in which the heat distribution and the cell reaction distribution are reduced by eliminating the above and making the air flow velocity distribution in the battery stack uniform.

First, the fuel cell system of the present invention will be described with reference to FIG.
The configuration of the fuel supply system 10 will be described. A hydrogen storage means 11 such as a compressed hydrogen cylinder or a hydrogen storage alloy is connected to a fuel inlet 101 of the fuel cell stack 100 via fuel gas supply channels 201A and 201B. The fuel gas supply passage 201A includes a hydrogen source valve 18, a primary pressure sensor S0, a regulator 19, a secondary pressure sensor S1, a first gas supply valve 20, a hydrogen pressure regulating valve 21, a second gas supply valve 22, and a tertiary pressure sensor. S2 is sequentially provided, and the fuel gas supply channel 201A is connected to one end of the fuel gas supply channel 201B. The other end of the fuel gas supply channel 201B is connected to the fuel intake port 101 of the fuel cell stack 100.

One end of a fuel discharge flow path 202 is connected to the fuel discharge port 102 of the fuel cell stack 100, and the other end is connected to a fuel gas supply flow path 201B to constitute a fuel gas circulation path. In the gas discharge channel 202, a trap 24, a circulation pump 25, and a circulation electromagnetic valve 26 are arranged in this order from the gas discharge port side of the fuel cell stack 100.
A water level sensor S10 is attached to the trap 24, and one end of the gas outlet path 203 is connected to the trap 24. The other end of the gas outlet path 203 is connected to the air duct 124. An exhaust solenoid valve 27 is provided in the gas outlet passage 203.

  Next, the air supply system 12 will be described. The air supply system 12 includes an air introduction path 123, an air supply duct 54, and an air discharge duct 124 that is an air discharge path. The air introduction path 123 is provided along the air flow direction in the order of the filter 121, the air fan 122, and the air supply duct 54.

In the air introduction path 123, there is provided a diffusion member 123m composed of a plate-like mesh, a honeycomb or the like, which is a diffusion means, and further, on the downstream side, the humidification is provided at a position immediately before the air supply duct 54. A nozzle 55 for injecting cooling water into the air introduction path 123 is provided. The nozzle 55 may be provided in the air introduction duct 54.
An air fan 122 serving as a blowing means is connected to the intake port at the end of the air introduction side of the air introduction path 123. A filter 121 is provided at the suction port of the air fan 122, and dust such as dust is removed during suction. The air fan 122 is a centrifugal blower that blows air by rotating the rotating blades, and a motor M for rotating the rotating blades is connected to a rotating shaft of the rotating blades.

  The diffusion member 123m covers the entire cross section of the air introduction path 123, and the air sent to the air manifold 54 is configured to be diffused when passing through the diffusion member 123m and flow uniformly in the air introduction path. Yes.

Next, the air exhaust side of the fuel cell will be described. An air discharge duct 124 is provided on the air outlet side of the fuel cell stack 100 in a direction parallel to the opening surface of the air discharge port of the fuel cell stack 100, and a baffle is attached to the air discharge duct 124. The flow rate of air in the fuel cell stack is made uniform.
The air that has flowed out from the air discharge duct 124 is discharged to the outside through the condenser 51. A condenser 51 to which a fan is attached is provided at the end of the air duct 124, and a filter 125 is subsequently connected. The condenser 51 extracts moisture from the air. Further, the water evaporated in the fuel cell stack 100 among the water supplied from the nozzle 55 is also collected here. The air duct 124 is provided with an exhaust temperature sensor S9, and the temperature in the fuel cell stack 100 is indirectly detected.

  Next, the water supply system will be described. The water supply system 50 includes a water tank 531 as water storage means, a water conduit 57 that guides the water collected by the condenser 51 to the water tank 531, and a water supply pipe 56 that guides the water in the water tank 531 to the nozzle 55 described above. Have. A collection pump 62 is provided in the water conduit 57. The recovery pump 62 sends the water extracted from the exhaust gas by the condenser 51 to the water tank 531. Further, the water supply pipe 56 is provided with a filter 64 and a supply pump 61 as water supply means in order. The water tank 531 is provided with a tank water level sensor S7 which is a storage amount detection means.

  A load system 7 is connected to the fuel cell stack 100, and electric power output from the fuel cell stack 100 is supplied to the load system 7. An electrode end of the fuel cell stack 100 is connected to an inverter 73 via a wiring 71, and electric power is supplied from the inverter 73 to a load such as a motor. An auxiliary power source 76 is connected to the inverter 73 via switching means 75 such as a semiconductor switching element such as an IGBT. The auxiliary power source 76 can be constituted by, for example, a secondary battery, a battery double layer capacitor, or the like. The load system 7 is provided with a voltage sensor S4 for detecting the output voltage of the fuel cell stack 100 and a current sensor S3 for detecting the output current.

  The control system of the fuel cell system 1 receives the detection values of the sensors S0 to S4, S7, S9, and S10, the regulator 19, the solenoid valves 18 to 19, 20, 22, 26, 27, and the pumps 25, 61. 62, an air fan 122, a fan of the condenser 51, an inverter 73, and a control device (ECU) for controlling the switching means 75. An ignition switch (not shown) is connected to the control device, and an instruction signal for driving or stopping a drive motor for driving the vehicle is input.

FIG. 2 is a diagram illustrating an embodiment of the fuel cell system of the present invention.
FIG. 2 (A) is a diagram for explaining one embodiment of the fuel cell system of the present invention, and FIG. 2 (B) is a diagram for explaining another embodiment, both of which are viewed from the side. It is a figure explaining arrangement | positioning of an element.
In the fuel cell system 1 shown in FIG. 2A, the fuel cell stack is arranged in the direction parallel to the opening surface of the air inlet 103 at the air inlet 103 at the top of the fuel cell stack in which a plurality of unit fuel cells are stacked. An air supply duct 54 that forms a flow path having the air inlet 103 as an end is coupled. Here, the direction parallel to the opening surface means that it is not parallel in a strict sense, but is substantially transverse to the opening surface of the horizontal air inlet.

  The air supply duct 54 is connected to an air fan 122 that sucks and blows air. Air is blown by an air fan at a pressure of 0.1 kPa to 3 kPa from the atmospheric pressure and slightly higher than the atmospheric pressure, which is generally referred to as normal pressure. In addition, a diffusion member 123 m that diffuses air is provided in the air introduction path 123 coupled to the air supply duct 54.

  An air exhaust duct 124 that forms a flow path in the same direction as the flow direction of the air flow in the air supply duct 54 is coupled in parallel to the opening surface of the air discharge port 104 in the lower part of the fuel cell stack 100. From the downstream end 104A of the air exhaust duct 124 of the air exhaust port 104 of the fuel cell stack, the air exhaust duct 104 extends in a direction toward the center of the air exhaust port 104 toward the air exhaust duct surface facing the air exhaust port. A baffle 105 that restricts the flow path of the air exhaust duct is provided. The air containing water vapor exiting the air exhaust duct separates water by the condenser 51 and is discharged to the outside.

FIG. 2B is a diagram for explaining another embodiment. In the example shown in FIG. 2A, the baffle is provided at the end 104A on the downstream side of the air exhaust duct 124 of the air discharge port 104 of the fuel cell stack 100, whereas FIG. ), A baffle 105A is provided at the downstream end 104A, and an air exhaust from the upstream end 104B to the upstream end 104B of the air exhaust duct 124 of the air exhaust port 104 is provided. A baffle 105B is provided in the central direction of the outlet 104, extending incline toward the air exhaust duct surface facing the air discharge port and restricting the flow path of the air exhaust duct.
As described above, it is possible to reduce the distribution of flow velocity generated in the fuel cell stack by providing a baffle in the air exhaust duct and reducing the distribution of the differential pressure between the upper and lower portions of the fuel cell, that is, the deviation. Become.
The baffle preferably extends to a position that is 75% to 80% of the half length of the air discharge port of the fuel cell stack. Further, the height is preferably extended to about half the position from the opening surface of the discharge port to the wall surface of the exhaust duct.

FIG. 3 is a diagram illustrating an example of the flow velocity distribution in the fuel cell stack.
In FIG. 3, the horizontal axis indicates the distance from the air supply fan side of the fuel cell stack, and the vertical axis indicates the flow velocity.
In the case where no baffle is installed, the flow velocity greatly decreases from the fan side toward the outlet side, whereas one baffle is provided only on the outlet side toward the center. This shows that the flow velocity distribution is greatly improved in both cases and when the baffle is provided on the fan side.

FIG. 4 is a diagram illustrating an example of a baffle.
FIG. 4A is a perspective view illustrating a baffle, and the baffle 105 can be made of a corrosion-resistant metal or synthetic resin plate. The baffle 105 is preferably provided with a column 105C and a side column 105D to prevent deflection.
Moreover, it is preferable to arrange a gasket 107 or other sealing material at the meeting portion of the baffle 105 and the fuel cell stack 100 so that air does not leak from the gap.
FIG. 4B is a side view for explaining the installation state of the baffle, which is an example in which only one baffle is arranged. The gasket 107 is arranged on the peripheral edge portion 100A of the fuel cell stack 100 to baffle. A gap is not generated between 105 and the peripheral portion 100A.
A spacer 108B is disposed on the other peripheral edge portion 100B to hold the fuel cell stack 100.
FIG. 4C is another side view for explaining the installation state of the baffle, which is an example in which only one baffle is arranged. In addition to the spacer 108A, the peripheral portion 100A of the fuel cell stack 100 is shown in FIG. A gap between the gasket 107, the baffle 105, and the peripheral edge portion 100A is prevented from being generated. A spacer 108B is disposed on the other peripheral edge portion 100B.

  In the fuel cell system of the present invention, a baffle extending at an inclination from the end of the air exhaust duct at the downstream side of the air exhaust duct toward the center is disposed at the air exhaust duct of the fuel cell stack. The flow path inside the fuel cell stack is reduced by reducing the pressure distribution (deviation) generated on the downstream side of the air exhaust duct of the fuel cell stack. Therefore, it is possible to prevent the deterioration of characteristics caused by the non-uniform flow rate. In addition, it is extremely useful for an atmospheric pressure type fuel cell system.

It is a figure explaining the fuel cell system of the present invention. FIG. 2 is a diagram illustrating an embodiment of the fuel cell system of the present invention. FIG. 3 is a diagram illustrating an example of the flow velocity distribution in the fuel cell stack. FIG. 4 is a diagram illustrating an example of a baffle. FIG. 5 is a diagram illustrating an example of a normal-pressure operating fuel cell system. FIG. 6 is a diagram for explaining another example of the fuel cell system.

Explanation of symbols

1 ... Fuel cell system,
DESCRIPTION OF SYMBOLS 100 ... Fuel cell stack, 100A, 100B ... Peripheral part 104 of fuel cell stack ... Air discharge port, 104A ... End part on downstream side, 104B ... End part 105, 105A, 105B on upstream side ... Baffle, 105C ... Strut, 105D ... Side column 107 ... Gasket 108, 108A, 108B ... Spacer 123 ... Air introduction path, 123m ... Diffusion member, 124 ... Air exhaust duct 130 ... Installation space 54 ... Air supply duct

Claims (3)

A rectangular parallelepiped fuel cell stack having an air inlet formed on the upper surface and an air outlet formed on the lower surface, and connected to the air inlet and substantially parallel to the upper surface of the fuel cell stack from one of the fuel cell stacks An air supply duct that introduces air and supplies air to the air inlet, and is connected to the air discharge port, and exhausts the air discharged from the fuel cell stack to the other substantially parallel to the lower surface of the fuel cell. A fuel cell system comprising an air exhaust duct, wherein a baffle for reducing a flow velocity distribution of air discharged from the air discharge port is installed below the fuel cell stack. . 2. The fuel cell according to claim 1, wherein the baffle is disposed so as to be inclined downward from a lower end opposite to an air introduction direction of the fuel cell stack toward a center of the fuel cell stack. system. 3. The fuel cell system according to claim 1, further comprising air supply means for supplying normal pressure air to the fuel cell stack through the air supply duct.

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