JP2008269844A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve downsizing of a cooling device of a fuel cell while improving cooling efficiency of the cooling device of a fuel cell system. <P>SOLUTION: The cooling device is equipped with a vapor-liquid separating means 16 to separate moisture from an oxidizer gas discharged from the fuel cell 10, a heat exchanger 23 having a heat exchange part 40a to heat exchange cooling water of the fuel cell with the exterior air, and a water supply part 40b to which water separated by the vapor-liquid separating means 16 is supplied, and a pressure reducing means to reduce the pressure of the water supply part 40b of the heat exchanger 23. In the heat exchanger 23, evaporation of water is promoted by means that the water supply part 40b is pressure-reduced by the pressure reducing means, and cooling water is cooled by vaporization latent heat of water. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a fuel cell system including a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen, and power generation for moving bodies such as vehicles, ships, and portable generators equipped with a refrigeration cycle for air conditioning. It is effective when applied to a machine.

  Conventionally, a fuel cell system including a fuel cell that generates power using a chemical reaction between hydrogen and oxygen (air) is known. In a fuel cell, moisture and heat are generated by a chemical reaction during power generation. The fuel cell needs to be maintained at about 80 ° C. for power generation efficiency, and most of the heat generated during power generation is discharged to the atmosphere by a radiator (air cooling type cooling device) through a refrigerant such as water. However, in the fuel cell system, the amount of heat generated is smaller than that of the internal combustion engine, and the air-water temperature difference between the cooling water temperature of the fuel cell and the outside air temperature is reduced by about 50%, which is disadvantageous for cooling by the radiator.

For this reason, the generated water generated by the power generation of the fuel cell is directly sprayed on the radiator or sprayed into the air blown to the radiator, and by using the latent heat of vaporization of the generated water, the amount of heat released from the radiator is increased. There is known a fuel cell system that is miniaturized (see, for example, Patent Document 1).
JP 2001-313054 A

  However, since the operating temperature of a typical fuel cell is about 80 ° C., even if the generated water is sprayed directly on the radiator or sprayed into the air blown to the radiator, a part of the generated water is vaporized. The cooling efficiency of the cooling water may not be improved because it passes as it is.

  An object of the present invention is to reduce the size of a cooling device for a fuel cell while improving the cooling efficiency of the cooling device for the fuel cell system.

  In order to achieve the above object, in the present invention, a fuel cell (10) that obtains electric power by chemically reacting hydrogen and oxygen, and gas-liquid separation that separates moisture from an oxidant gas discharged from the fuel cell (10). Means (16), a heat exchange part (40a) for exchanging heat between the cooling water of the fuel cell (10) and the outside air, and a water supply part (40b) to which water separated by the gas-liquid separation means (16) is supplied. ) And a pressure reducing means for depressurizing the water supply part (40b) of the heat exchanger (23). In the heat exchanger (23), the water supply part (40b) is provided by the pressure reducing means. ) Is accelerated to evaporate water, and cooling water is cooled by latent heat of vaporization of water.

  Thereby, the water | moisture content produced | generated at the time of electric power generation can be utilized effectively to the maximum, and the heat dissipation in a heat exchanger (23) can be increased. Moreover, compared with the case where it cools by spraying produced | generated water directly to a heat exchanger (23) like the past, water pressure part (40b) of a heat exchanger (23) is pressure-reduced by a pressure reduction means, Since the vaporization of can be promoted, the cooling efficiency can be improved. Furthermore, since the amount of heat released by outside air in the heat exchanger (23) can be reduced, the heat exchanger (23) can be reduced in size.

  An ejector (33) that injects oxidant gas from the nozzle part (33a) and sucks fluid from the suction port (33b) by the flow of the oxidant gas injected from the nozzle part (33a). (33b) is configured to be connected to the water supply part (40b) of the heat exchanger (23), thereby utilizing the fluid energy of the oxidant gas discharged from the fuel cell (10), Since the water supply part (40b) of the heat exchanger (23) can be depressurized, the cooling efficiency by the heat exchanger (23) can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  In this embodiment, the fuel cell system is applied to an electric vehicle (fuel cell vehicle) that runs using the fuel cell 10 as a power source.

  FIG. 1 is a main configuration diagram of a fuel cell system according to the present embodiment. As shown in FIG. 1, the fuel cell system includes a fuel cell 10 that generates electric power using an electrochemical reaction between hydrogen and oxygen. The fuel cell 10 is configured to supply power to power devices such as a secondary battery, a traveling motor, and an auxiliary machine. Here, hydrogen corresponds to the fuel gas of the present invention, and air containing oxygen corresponds to the oxidant gas of the present invention.

  In the present embodiment, a solid polymer electrolyte fuel cell is used as the fuel cell 10, and there are a plurality of cells each composed of an MEA having electrodes joined to both side surfaces of the electrolyte membrane and a pair of separators sandwiching the MEA. They are stacked and electrically connected in series. In the fuel cell 10, the following electrochemical reaction between hydrogen and oxygen occurs, and electric energy is generated.

(Hydrogen electrode side) H ₂ → 2H ⁺ + 2e ⁻
(Oxygen electrode side) 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O
The fuel cell system is provided with a hydrogen supply path 11 through which hydrogen supplied to the hydrogen electrode of the fuel cell 10 passes and a hydrogen discharge path 12 through which hydrogen electrode side exhaust gas discharged from the hydrogen electrode of the fuel cell 10 passes. ing. A hydrogen supply device (not shown) for supplying hydrogen to the hydrogen electrode of the fuel cell 10 is provided at the most upstream portion of the hydrogen supply path 11.

  The fuel cell system includes an air supply path 13 through which air supplied to an air electrode (oxygen electrode) of the fuel cell 10 passes, and an air discharge through which air electrode side exhaust gas discharged from the air electrode of the fuel cell 10 passes. A path 14 is provided. The air supply path 13 is provided with an air supply device 15 for supplying air. Note that the air (air electrode side exhaust gas) discharged from the fuel cell 10 is in a high temperature state due to the heat transferred from the fuel cell 10.

  When the fuel cell 10 generates power, moisture and heat are generated by the electrochemical reaction. The fuel cell 10 needs to be maintained at a constant temperature during operation to ensure power generation efficiency. Further, since the electrolyte membrane inside the fuel cell 10 exceeds a predetermined allowable upper limit temperature and is destroyed by high temperature, it is necessary to keep the temperature of the fuel cell 10 below the allowable temperature.

  Therefore, the fuel cell system is provided with a cooling system that cools the fuel cell 10 so that the operating temperature becomes a temperature suitable for the electrochemical reaction (for example, about 80 ° C.).

  The cooling system includes a refrigerant circulation path 20 that circulates cooling water (refrigerant) in the fuel cell 10, a refrigerant circulation pump 21 that circulates cooling water, an electric motor (not shown) that drives the refrigerant circulation pump 21, and a fan 22. The provided radiator 23 is provided. The heat generated in the fuel cell 10 is radiated to the atmosphere by the radiator 23 that exchanges heat between the cooling water and the outside air. The radiator 23 corresponds to the heat exchanger of the present invention.

  The radiator 23 used in this embodiment will be described with reference to FIGS. 2 (a) and 2 (b). Fig.2 (a) is a perspective view of the radiator used by this embodiment, FIG.2 (b) is a perspective view of the tube in Fig.2 (a).

  As shown in FIG. 2, the radiator 23 includes a tube 40 through which cooling water and water separated by a gas-liquid separator 16 (to be described later) flow, a fin that is joined to the outer surface of the tube 40 and increases the heat transfer area with air. 41, an inlet / outlet tank 42 provided at both ends in the longitudinal direction of the tube 40, and the like.

  The tube 40 has a heat exchange path 40a through which cooling water flows and a water supply path 40b through which water separated by the gas-liquid separator 16 described later flows. The heat exchange path 40a and the water supply path 40b are provided in parallel to the longitudinal direction of the tube 40. Here, the heat exchange path 40a and the water supply path 40b in the tube 40 are configured to be able to exchange heat. The heat exchange path 40a corresponds to the heat exchange section of the present invention, and the water supply path 40b corresponds to the water supply section of the present invention.

  The inlet / outlet tank 42 includes a cooling water inlet / outlet tank 42a communicating with the heat exchange path 40a in the tube 40 and a water inlet / outlet tank 42b communicating with the water supply path 40b. The cooling water inlet / outlet tank 42 a and the water inlet / outlet tank 42 b are arranged in parallel in the longitudinal direction of the inlet / outlet tank 42.

  Returning to FIG. 1, the moisture generated during power generation in the fuel cell 10 is discharged from the fuel cell 10 into the air discharge path 14 while being contained in the air. Therefore, the fuel cell system of the present embodiment is provided with a gas-liquid separator 16 that separates moisture generated during power generation into air and water on the downstream side of the fuel cell 10 in the air discharge path 14. The gas-liquid separator 16 corresponds to the gas-liquid separation means of the present invention.

  The air separated by the gas-liquid separator 16 is discharged to the outside. On the other hand, the water separated by the gas-liquid separator 16 is supplied to the radiator 23 via the branch path 30.

  A shut valve 31 for adjusting the flow rate of water flowing through the branch path 30 is provided on the upstream side of the radiator 23 in the branch path 30. A vacuum pump 32 is provided on the downstream side of the radiator 23 in the branch path 30.

  The vacuum pump 32 vacuums the air discharged through the branch path 30 and depressurizes the downstream side of the shut valve 31 in the branch path 30. Here, the vacuum pump 32 in the present embodiment corresponds to the decompression means of the present invention, and is used to decompress the water supply path 40b of the heat exchanger 23.

  In the fuel cell system configured as described above, air and hydrogen are supplied from the air supply path 14 and the hydrogen supply path 11 to the fuel cell 10, so that the fuel cell 10 generates power. With the power generation of the fuel cell 10, water is generated on the air electrode side of the fuel cell 10, and this water is discharged from the fuel cell 10 in a state of being contained in the air.

  The air containing water discharged from the fuel cell 10 is separated into water and air by the gas-liquid separator 16. The air separated by the gas-liquid separator 16 is discharged to the outside through the air discharge path 14. The water separated by the gas-liquid separator 16 is once stored in the gas-liquid separator 16 in a state where the temperature is lowered by condensation, and the radiator 23 is connected via the branch path 30 by opening the shut valve 31. Into the water supply path 40b.

  On the other hand, the cooling water of the cooling system is supplied to the heat exchange path 40 a of the radiator 23 by circulating the cooling water in the refrigerant circulation path 20 by driving the refrigerant circulation pump 21.

  At this time, the downstream side of the shut valve 31 in the branch path 30 is depressurized by the vacuum pump 32 provided downstream of the radiator 23 in the branch path 30. Therefore, the pressure in the water supply path 40b of the radiator 23 decreases, and the vaporization of water in the water supply path 40b is promoted. Thereby, the cooling water which flows through the heat exchange path 40a can be cooled by the vaporization latent heat of the water in the water supply path 40b.

  As described above, the heat generated in the radiator 23 can be increased by maximally effectively using the moisture generated during power generation. In addition, the cooling of the water supply path 40b of the radiator 23 is reduced by the vacuum pump 32, so that the water in the water supply path 40b is evaporated, compared with the conventional case where the generated water is directly sprayed on the radiator 23 for cooling. The cooling water flowing through the heat exchange path 40a can be cooled by the latent heat of vaporization of water. Furthermore, since the amount of heat released by the outside air in the radiator 23 can be reduced, the radiator 23 can be reduced in size.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, only parts different from the first embodiment will be described.

  In the first embodiment, the vacuum pump 32 for reducing the pressure of the water passing through the water supply path 40b of the radiator 23 is provided on the downstream side of the radiator 23 in the branch path 30, but in the second embodiment, the vacuum pump Instead of 32, an ejector 33 is provided.

  In the present embodiment, an ejector 33 is provided at a merging portion on the downstream side of the gas-liquid separator 16 in the air discharge path 14 and on the downstream side of the radiator 23 of the branch path 30 branched from the air discharge path 14.

  The ejector 33 is a momentum transport type pump that transports fluid by the energy exchange action of the working fluid ejected at high speed. Specifically, the ejector 33 uses the fluid energy of the air discharged through the air discharge path 14, The air exhausted through the branch path 30 is sucked and a negative pressure is generated on the downstream side of the shut valve 31 in the branch path 30. Here, the ejector 33 in the present embodiment corresponds to the decompression means of the present invention, and is used to decompress the water supply path 40b of the heat exchanger 23.

  In the ejector 33, the passage area of the air discharged through the air discharge path 14 is narrowed down so as to communicate with the nozzle portion 33a that decompresses and expands the air isentropically and the ejection port of the nozzle portion 33a. A suction port 33 b that is disposed and sucks the fluid discharged through the branch path 30 is provided. Further, on the downstream side of the nozzle portion 33a and the suction port 33b, a mixing portion 33c that mixes high-speed air from the nozzle portion 33a and air sucked from the suction port 33b is provided. And the diffuser part 33d which makes a pressure | voltage rise part is arrange | positioned downstream of the mixing part 33c. The diffuser portion 33d is formed in a shape that gradually increases the passage area of the refrigerant.

  The fluid flowing through the branch path 30 is sucked into the suction port 33b by the suction action of the air flow decompressed and expanded by the nozzle portion 33a. Along with this, a negative pressure is generated between the suction port 33 b of the ejector 33 from the downstream side of the shut valve 31 in the branch passage 30. Therefore, the pressure in the water supply path 40b of the radiator 23 decreases, and the vaporization of water in the water supply path 40b is promoted.

  In this way, by using the ejector 33 as the pressure reducing means, power is not required compared to the case where the vacuum pump is used as the pressure reducing means, so that the cooling efficiency of the cooling system can be improved.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, only portions different from the first embodiment will be described. 4A is a perspective view of the radiator used in the present embodiment, FIG. 4B is a front sectional view of FIG. 4A, and FIG. 4C is FIG. 4A. It is a perspective view of an inner tube.

  In the present embodiment, the configuration of the radiator 23 is different from the configuration of the first embodiment. In the said 1st Embodiment, although the heat exchange path | route 40a and the water supply path | route 40b are provided in the inside of the tube 40 of the radiator 23 so that it may become parallel to the tube 40 longitudinal direction, the tube 40 of the radiator 23 of this embodiment is provided. As shown in FIG. 4, a water supply path 40 b is provided inside the heat exchange path 40 a, and the tube 40 has a so-called double pipe structure. Here, the heat exchange path 40a and the water supply path 40b in the tube 40 are configured to be able to exchange heat.

  Also, a cooling water inlet / outlet tank 42a communicating with the heat exchange path 40a constituting the inlet / outlet tank 42 provided at both ends of the tube 40 in the longitudinal direction, and a water inlet / outlet tank 42b communicating with the water supply path 40b. The arrangement is configured such that the water inlet / outlet tank sandwiches the cooling water inlet / outlet tank.

  Even if the radiator 23 having such a configuration is used, the heat generated in the radiator 23 can be increased by effectively using the moisture generated during power generation.

It is a conceptual diagram of the fuel cell system of 1st Embodiment. It is a perspective view of the radiator of a 1st embodiment. It is a conceptual diagram of the fuel cell system of 2nd Embodiment. It is a perspective view of the radiator of a 3rd embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 14 ... Air discharge path, 16 ... Gas-liquid separator, 20 ... Refrigerant circulation path, 21 ... Refrigerant circulation pump, 23 ... Radiator, 30 ... Branch path, 31 ... Shut valve, 32 ... Vacuum pump, 33 ... ejector, 40 ... tube, 40a ... heat exchange path, 40b ... water supply path, 41 ... fin.

Claims (2)

A fuel cell (10) for obtaining electric power by chemically reacting hydrogen and oxygen;
Gas-liquid separation means (16) for separating moisture from the oxidant gas discharged from the fuel cell (10);
A heat exchange section (40a) for exchanging heat between the cooling water of the fuel cell (10) and the outside air; and a water supply section (40b) for supplying water separated by the gas-liquid separation means (16). A heat exchanger (23);
Pressure reducing means for reducing the pressure of the water supply part (40b) of the heat exchanger (23),
In the heat exchanger (23), the water supply part (40b) is depressurized by the depressurizing means to promote water evaporation, and the cooling water is cooled by latent heat of vaporization of water. Battery system. The decompression means ejects the oxidant gas from the nozzle part (33a), and ejects the fluid from the suction port (33b) by the flow of the oxidant gas ejected from the nozzle part (33a). Because
The fuel cell system according to claim 1, wherein the suction port (33b) is connected to the water supply unit (40b) of the heat exchanger (23).

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