JP2005149883A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the performance of a radiator and a fuel cell system through the recirculation of off-gas in the radiator. <P>SOLUTION: The fuel cell system 11 generating power by chemical reaction of fuel supplied to a fuel electrode 13 and gas supplied to an oxidant electrode 14 through an electrolyte film 12 is provided with the radiator 18 with a core 21 structured of a number of tubes 19 and fins 20, and an off-gas supply means 23 supplying the off gas generated at power generation to an outside face of the core 21 of the radiator 19. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that generates power by chemically reacting a fuel on the fuel electrode side and a gas on the oxidant electrode side through an electrolyte membrane.

  In recent years, as shown in FIG. 3, an automobile 2 equipped with a fuel cell system 1 that directly converts a chemical energy of a fuel into electric energy by chemically reacting a fuel such as hydrogen and a gas such as oxygen. Is attracting attention.

  A conventional fuel cell system 1 mounted on such an automobile 2 includes a fuel cell 3 provided with a fuel electrode and an oxidant electrode with an electrolyte membrane interposed therebetween, and a plurality of radiators for cooling the fuel cell 3 and the like. 4 are provided. The fuel cell 3 generates electric power by a chemical reaction between the fuel supplied to the fuel electrode and the gas supplied to the oxidant electrode, and the electric power is supplied to the drive unit of the automobile 2 or the like. At this time, off-gas containing a large amount of water is generated together with electric power in the fuel cell 3, and this off-gas is partly used for humidification of the fuel cell 3 and then discharged to the outside (for example, Patent Documents 1 and 2).

JP 2001-357864 A JP 2002-372385 A

  However, in the conventional fuel cell system 1 described above, most of the off-gas containing a large amount of moisture generated during power generation in the fuel cell 3 has been discharged to the outside, so that the performance of the radiator 4 and the fuel cell system 1 is sufficient. There was a problem that it could not be improved.

  The present invention has been made to solve the above-described problems, and provides a fuel cell system that can recycle off-gas to a radiator and improve the performance of the radiator and the fuel cell system.

  The present invention relates to a fuel cell system that generates electric power by chemically reacting a fuel supplied to a fuel electrode and a gas supplied to an oxidant electrode through an electrolyte membrane, and includes a plurality of tubes and fins. And a radiator having a core constituted by the above and off-gas supply means for supplying off-gas generated during power generation to the core outer surface of the radiator.

  Preferably, the off-gas supply means is provided with an injection port capable of injecting off-gas on the outer surface of the core of the radiator, and the injection port is formed so that a particle diameter of water in the injected off-gas is 200 μm or less. ing.

  According to the present invention, since the latent heat of vaporization of water in off-gas can be used, various excellent effects can be obtained, such as improving the performance of the radiator and the fuel cell system.

  Hereinafter, a fuel cell system according to an embodiment of the present invention will be described with reference to the drawings. In the following description, a case where the present invention is applied to a direct methanol fuel cell system for automobiles will be described as an example.

  1 and 2 show a fuel cell system according to an embodiment of the present invention. The direct methanol fuel cell system 11 includes a fuel cell 15 provided with a fuel electrode 13 and an oxidant electrode 14 with an electrolyte membrane 12 interposed therebetween, a fuel tank 16 for storing a methanol aqueous solution, and an outlet of the oxidant electrode 14. A condenser 17 provided on the side and a radiator 18 for cooling the fuel cell 15 are schematically configured.

  The radiator 18 is provided with a core 21 composed of a large number of tubes 19 and fins 20 (see FIG. 2), and a pair of tanks 22 are provided at both ends of the tube 19. Further, on the front side of the core 21 of the radiator 18, there is provided a pipe-like off-gas supply header 23 in which a large number of injection ports 25 (see FIG. 2) are formed toward the radiator 18, and on the rear surface side of the radiator 18. A fan 24 is provided. The injection port 25 of the off-gas supply header 23 is formed so that the moisture in the off-gas injected from the injection port 25 is fine mist, and preferably the particle size thereof is 200 μm or less.

  Next, the operation of the fuel cell system 11 according to the present embodiment will be described.

  When an aqueous methanol solution is supplied from the fuel tank 16 to the fuel electrode 13 and air is supplied to the oxidant electrode 14, the methanol and air chemically react with each other through the electrolyte membrane 12, and electric power is generated in the fuel cell 15. Occur. At this time, carbon dioxide and methanol aqueous solution are generated on the fuel electrode 13 side, and off-gas containing a large amount of moisture is generated on the oxidant electrode 14 side. The methanol generated on the fuel electrode 13 side is recirculated to the fuel tank 16, while the off gas generated on the oxidant electrode 14 side is supplied to the off gas after the moisture in the off gas is condensed in the condenser 17. It is injected from the injection port 25 of the header 23 to the core 21 outer surface side of the radiator 18.

At this time, since the offgas still contains a large amount of water, the water in the offgas is vaporized after adhering to the fins 20 as fine mist-like water droplets, and latent heat is generated from the refrigerant circulating in the tube 19. To cool the refrigerant. According to the experiment, if a heat dissipation amount of Q ₁ (kw) is obtained when v (kg / h) of water having latent heat of vaporization of h (kwh / kg) is injected to the radiator 18, the heat dissipation amount Q ₁ The relationship between (kw) and the heat dissipation amount Q ₂ (kw) of the radiator 18 when water is not injected is
_{Q 1 / Q 2 + vh <<} 100%
I know that Therefore, for example, if the surface temperature of the fin 20 of the radiator 18 is 80 ° C., the latent heat of evaporation h of water at 80 ° C. is
h = 551 kcal / kg = 22304.4 kJ / h
Therefore, when 1 kg / h of moisture is injected into the radiator 18, the heat dissipation amount Q ₁ due to the moisture is:
Q ₁ = 1 kg / h × 2304.3 kJ / h = 22304.3 kJ / h = 0.64 kW≈Q ₂
It becomes.

  Thus, latent heat substantially equal to the latent heat of evaporation of water can be taken from the refrigerant in the tube 19 as the moisture in the offgas evaporates. Further, since the moisture in the off gas is attached to the fins 20 in a fine mist-like water droplet state, the contact resistance is small. Therefore, the heat exchange performance of the radiator can be improved. Further, off-gas can be sucked to the radiator 18 side by exhaust pressure of the fuel cell 15 and driving of the fan 24, and it is not necessary to newly install a power source such as a pump, so that the cost can be reduced. .

  The means for supplying off gas to the outer surface of the core 21 of the radiator is not limited to the pipe-shaped header 23 described above, and other off gas supply means such as an air conditioning duct may be used.

  The timing at which off-gas is injected from the off-gas supply header 23 onto the outer surface of the core 21 may be configured to be controllable according to the load of the radiator 18.

  Furthermore, in the above-described embodiment, only the radiator 18 for cooling the fuel cell has been described for the sake of simplification. However, the fuel cell system 11 includes a radiator for cooling the reformer and a wheel driving device. Since a plurality of radiators such as a radiator for cooling a power control unit for controlling the drive motor are provided, the present invention can be applied to these radiators.

  Furthermore, it goes without saying that the present invention is applicable not only to the direct methanol fuel cell system 11 for automobiles but also to other types of fuel cell systems that use pure hydrogen, gasoline, methane gas or the like as fuel. Absent.

1 is a schematic configuration diagram showing a fuel cell system according to an embodiment of the present invention. It is a perspective view which shows the radiator and off-gas supply means in embodiment of this invention. It is a schematic block diagram which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Fuel cell system 12 Electrolyte membrane 13 Fuel electrode 14 Oxidant electrode 15 Fuel cell 18 Radiator 19 Tube 20 Fin 21 Core 23 Off-gas supply means 25 Injection port

Claims (2)

A fuel cell system that generates electric power by chemically reacting a fuel supplied to a fuel electrode and a gas supplied to an oxidant electrode through an electrolyte membrane,
A radiator having a core constituted by a large number of tubes and fins;
Off gas supply means for supplying off gas generated during power generation to the core outer surface of the radiator;
A fuel cell system comprising: The off-gas supply means is provided with an injection port capable of injecting off-gas on the outer surface of the core of the radiator, and the injection port is formed so that the particle size of water in the injected off-gas is 200 μm or less. Item 4. The fuel cell system according to Item 1.

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