Fuel cell system and power generating method in fuel cell system

• US 20050164055A1
• Filed: 11/29/2004
• Published: 07/28/2005
• Est. Priority Date: 12/17/2003
• Status: Abandoned Application

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Higashionji, Masaru, Hasegawa, Kenji, Odagiri, Masaru, Shimotashiro, Masafumi, Hori, Kenya, Ono, Masayuki, Aoyama, Toshiyuki
• Application Number:
  US10/998,162
• Publication Number:
  US 20050164055A1
• Time in Patent Office: Days
• US Class Current: 429/413
• CPC Class Codes: H01M 8/04186 of liquid-charged or electrolyte-charged reactants
• CPC Class Codes: H01M 8/04201 Reactant storage and supply, e.g. means for feeding, pipes
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04228 during shut-down
• CPC Class Codes: H01M 8/043 applied during specific periods
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/04303 applied during shut-down
• CPC Class Codes: H01M 8/04388 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04604 Power, energy, capacity or load
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/1011 Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system has a controller in communication with a fuel detector for activating power supply if a detection result received from the fuel detector indicates that a level of the liquid fuel has not reached the top of an anode, and for preventing power generation in a fuel cell until the detection result indicates that the level of the liquid fuel has reached the top of the anode.

Claims

1. A fuel cell system comprising:

a fuel cell including an anode, a cathode disposed so as to face the anode, and a membrane electrode assembly disposed between the anode and the cathode;

a fuel pump for feeding liquid fuel to the anode wherein the anode is immersed when the liquid fuel reaches a top of the anode;

a fuel detector for detecting a level of the liquid fuel relative to the top of the anode;

a power supply for feeding electric power necessary for driving the fuel pump; and

a controller in communication with the fuel detector for activating the power supply if a detection result received from the fuel detector indicates that a level of the liquid fuel has not reached the top of the anode, and for preventing power generation in the fuel cell until the detection result indicates that the level of the liquid fuel has reached the top of the anode.

2. The fuel cell system as defined in claim 1, wherein the controller is operable to command the fuel pump to feed the liquid fuel and to allow the power generation in the fuel cell after the detection of the reach of the liquid fuel by the fuel detection section.

3. The fuel cell system as defined in claim 1, wherein the power supply is configured to supply power necessary for the detector to detect the liquid fuel.

4. The fuel cell system as defined in claim 1, further comprising a fuel container in which at least the anode of the fuel cell is disposed for containing the liquid fuel received via the fuel pump.

5. The fuel cell system as defined in claim 1, wherein the power supply is a secondary battery.

6. The fuel cell system as defined in claim 1, further comprising:

a first fuel container in which at least the anode of the fuel cell is disposed for containing liquid fuel; and

a second fuel container for containing liquid fuel with a concentration higher than that of the liquid fuel contained in the first fuel container;

wherein the fuel pump feeds liquid fuel from the second fuel container to the first fuel container.

7. The fuel cell system, comprising:

a fuel cell including an anode, a cathode disposed so as to face the anode, and a membrane electrode assembly disposed between the anode and the cathode;

a first fuel container in which at least the anode of the fuel cell is disposed for containing liquid fuel;

a second fuel container for containing liquid fuel having a concentration higher than that of the liquid fuel contained in the first fuel container; and

a fuel pump for feeding the liquid fuel from the second fuel container to the first fuel container during a power generating operation in the fuel cell; and

a switch valve disposed between the first fuel container and the second fuel container operative to feed the liquid fuel from the second fuel container to the first fuel container during a time when the power generation has stopped.

8. The fuel cell system as defined in claim 7, wherein

the second fuel container is disposed at a position higher than the first fuel container,

in a first position of the switch valve, the liquid fuel from the second fuel container flows to the first fuel container due to gravity, and

in a second position of the switch valve, the liquid fuel from the second fuel container flows to the first fuel container via the fuel pump.

9. The fuel cell system as defined in claim 8, further comprising a controller for detecting the power generation for switching the switch valve between the first position and the second position.

10. The fuel cell system as defined in claim 7, further comprising:

a power generating circuit for connecting the anode and the cathode;

a detector for detecting a content of the liquid fuel in the first fuel container; and

a circuit-breaking switch for activating the power generating circuit during the power generating operation, and for deactivating the power generating circuit during a stop time of the power generation, wherein

when the detector detects a content of the liquid fuel with which at least a part of the membrane electrode assembly is exposed out of the liquid fuel contained in the first fuel container, the circuit-breaking switch is deactivated or maintained in a deactivating state.

11. The fuel cell system as defined in claim 9, further comprising:

a product collecting container for collecting a product produced in the cathode by the power generation in the fuel cell; and

a recirculation pump for feeding the product from the product collecting container to the first fuel container.

12. The fuel cell system as defined in claim 11, wherein the product collecting container is disposed at a position higher than the first fuel container for feeding the product from the product collecting container to the first fuel container with effect of gravity.

13. The fuel cell system as defined in claim 12, further comprising a switch valve disposed between the product collecting container and the first fuel container operative to control feeding the product from the product collecting container to the first fuel container during power generation.

14. The fuel cell system as defined in claim 13, further comprising a concentration detector for detecting a concentration of the liquid fuel contained in the first fuel container, wherein

the controller is operable to control a feed amount of the liquid fuel concentrate fed to the first fuel container and a feed amount of the product fed to the first fuel container so that the concentration is within a predetermined concentration range.

15. The fuel cell system as defined in claim 11, wherein the product contains water as a main ingredient, and the liquid fuel contained in the first fuel container is the liquid fuel concentrate diluted by adding water.

16. The fuel cell system as defined in claim 7, wherein the liquid fuel is a methanol solution having a concentration in a range of 1 to 10 wt % that is a concentration range allowing the power generation, and the liquid fuel concentrate is a methanol solution having a concentration higher than that of the methanol solution or a methanol concentrate.

17. A fuel cell system comprising:

a fuel cell including an anode, a cathode disposed so as to face the anode, a membrane electrode assembly disposed between the anode and the cathode, and a power generating circuit for connecting the anode and the cathode;

a fuel container in which at least the anode of the fuel cell is disposed for containing the liquid fuel;

a content detector for detecting a content of the liquid fuel in the fuel container;

a circuit-breaking switch for activating the power generating circuit during the power generating operation, and for deactivating the power generating circuit during a stop time of the power generation; and

a controller for changing the circuit-breaking switch to a deactivating position or for maintaining the deactivating position when the content detector detects a content of the liquid fuel with which at least a part of the anode is exposed out of the liquid fuel contained in the fuel container.

18. A fuel system comprising:

a fuel cell including an anode which has a passageway of liquid fuel, a cathode disposed so as to face the anode and a membrane electrode assembly disposed between the anode and the cathode;

a fuel pump for feeding liquid fuel to the anode by passing through the liquid fuel from an inlet to an outlet of the passageway;

a fuel detector for detecting that the liquid fuel reaches the outlet of the passageway in the anode;

a power supply for feeding electric power necessary for driving the fuel pump; and

a controller in communication with the fuel detector for activating the power supply if a detection result received from the fuel detector indicates that the liquid fuel has not reached the outlet of the passageway in the anode, and for preventing power generation in the fuel cell until the detection result indicates that the liquid fuel has reached the outlet of the passageway.

19. A fuel system as defined in claim 18, further comprising a fuel detector which is placed in the inlet of the passageway or on the way of the passageway, for detecting that the liquid fuel reaches thereto, wherein

the controller communicates with the both fuel detectors and activates the power supply if either of detection results received from each of the fuel detectors indicate that the liquid fuel has not reached thereto, and prevents power generation in the fuel cell until both of the detection results indicate reaching of the liquid fuel.

20. A power generating method in a fuel cell system made up of a fuel cell including an anode, a cathode and a membrane electrode assembly, a first fuel container for containing liquid fuel, and a second container for containing a liquid fuel concentrate with a concentration higher than that of the liquid fuel, the method comprising the steps of:

immersing the anode in the liquid fuel during a stop time of power generation in the fuel cell; and

supplementing liquid fuel consumed by the power generation in the first container during the power generating operation in the fuel cell in order to perform continuous generation of a specified amount of electric power in the fuel cell.

21. A power generating method in a fuel cell system, comprising the steps of:

before staring power generation in a fuel cell,

detecting whether or not an anode is immersed in liquid fuel, and

feeding liquid fuel to the anode if it is determined based on a detection result that the anode is not immersed in liquid fuel until the anode is immersed in liquid fuel; and

generating power in the fuel cell after the anode is immersed in liquid fuel.