Fuel cell system

• US 20030031905A1
• Filed: 07/29/2002
• Published: 02/13/2003
• Est. Priority Date: 08/10/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Saito, Tomohiro, Okamoto, Kunio, Kawai, Toshiyuki, Osaki, Akimasa, Kudou, Hiroyasu
• Granted Patent: US 7,179,556 B2
• Time in Patent Office: Days
• US Class Current: 429/26
• CPC Class Codes: H01M 8/0267 having heating or cooling means, e.g. heaters or coolant flow channels
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04029 Heat exchange using liquids
• CPC Class Codes: H01M 8/04037 Electrical heating
• CPC Class Codes: H01M 8/04074 Heat exchange unit structures specially adapted for fuel cell
• CPC Class Codes: H01M 8/04097 with recycling of the reactants H01M8/04119, H01M8/04104 take precedence
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04268 Heating of fuel cells during the start-up of the fuel cells
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/04358 of the coolant
• CPC Class Codes: H01M 8/04365 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04417 of the coolant
• CPC Class Codes: H01M 8/04723 of the coolant
• CPC Class Codes: H01M 8/04731 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04768 of the coolant
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: H01M 8/2457 with both reactants being gaseous or vaporised
• CPC Class Codes: H01M 8/2483 characterised by internal manifolds
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell system includes a fuel cell constructed by plural stacked cells, a circulation path through which a thermal medium is circulated into each cell, a heater for heating the thermal medium, a bypass path through which the thermal medium is circulated into a part of each cell while bypassing the other part thereof, and a flow control valve for controlling a flow amount of the thermal medium circulated in the bypass path. The thermal medium can be circulated into only the part of each cell in a warm-up operation, so that the part of each cell is collectively heated. An amount of the thermal medium circulated into the other part of each cell is controlled, so that all of each cell is finally warmed up in the warm-up operation.

Claims

1. A fuel cell system comprising

a fuel cell including a plurality of stacked cells, for generating electric power by an electrochemical reaction of hydrogen and oxygen;

wherein a part of each cell is collectively heated when the fuel cell is warmed up in a warm-up operation.

2. The fuel cell system according to claim 1, further comprising:

a thermal medium circulation path through which a thermal medium is circulated into each cell;

a first thermal medium circulation device which controls an amount of the thermal medium circulated in the thermal medium circulation path;

a heating device for heating the thermal medium;

a bypass path through which the thermal medium only flows into a part of each cell while bypassing the other part of each cell, the bypass path being provided in the thermal medium circulation path; and

a second thermal medium circulation device provided in at least one of the bypass path and the thermal medium circulation path, for controlling an amount of the thermal medium circulated in the bypass path.

3. The fuel cell system according to claim 2, further comprising:

a first temperature detection device disposed to detect a temperature of each cell at the part collectively heated; and

a controller for controlling operation of the fuel cell, wherein;

the controller controls the heating device to control a heating degree of the thermal medium using the heating device, controls the first thermal medium circulation device to control the amount of the thermal medium circulated into the thermal medium circulation path, and controls the second thermal medium circulation device to control the amount of the thermal medium circulated in the bypass path, based on the temperature detected by the first temperature detection device.

4. The fuel cell system according to claim 3, wherein:

the first thermal medium circulation device and the second thermal medium circulation device are operated such that all the thermal medium flows into the bypass path to be circulated into only the part of each cell in the warm-up operation when the temperature detected by the first temperature detection device is lower than a first predetermined temperature; and

when the temperature detected by the first temperature detection device is higher than the first predetermined temperature, the amount of the thermal medium circulated into the other part of each cell is adjusted by adjusting the amount of the thermal medium circulated in the bypass path based on the temperature detected by the first temperature detection device while the oxygen and the hydrogen are supplied to the cells in the warm-up operation.

5. The fuel cell system according to claim 2, wherein:

each cell includes a thermal medium inlet from which the thermal medium flows into each cell, the thermal medium inlet being provided around one outlet of the hydrogen and the oxygen; and

each cell includes a thermal medium outlet from which the thermal medium flows out from each cell, the thermal medium outlet being provided around one inlet of the hydrogen and the oxygen.

6. The fuel cell system according to claim 2, wherein:

each cell includes a thermal medium inlet from which the thermal medium flows into each cell, the thermal medium inlet being provided around one inlet of the hydrogen and the oxygen; and

each cell includes a thermal medium outlet from which the thermal medium flows out from each cell, the thermal medium outlet being provided around one outlet of the hydrogen and the oxygen.

7. The fuel cell system according to claim 1, further comprising:

a thermal medium circulation path through which a thermal medium is circulated into each cell;

a bypass path through which the thermal medium is circulated into only a part of each cell while bypassing the other part of each cell, the bypass path being provided in the thermal medium circulation path; and

a flow switching device for switching a flow direction of the thermal medium in the thermal medium circulation path when the thermal medium is circulated into only the part of each cell through the bypass path.

8. The fuel cell system according to claim 1, further comprising

an oxygen flow switching device for switching a flow direction of the oxygen to be supplied to each cell.

9. The fuel cell system according to claim 1, further comprising

a hydrogen flow switching device for switching a flow direction of the hydrogen to be supplied to each cell.

10. The fuel cell system according to claim 1, further comprising:

a thermal medium circulation path through which a thermal medium is circulated into each cell;

a first thermal medium circulation device for controlling an amount of the thermal medium circulated into the thermal medium circulation path;

a bypass path through which the thermal medium is circulated into only a part of each cell while bypassing the other part of each cell, the bypass path being provided in the thermal medium circulation path;

a cooling device provided in the thermal medium circulation path, for cooling the thermal medium;

a heating path provided in the thermal medium circulation path in parallel with the cooling device;

a heating device provided in the heating path, for heating the thermal medium; and

a flow switching device for switching a flow of the thermal medium to one of the cooing device and the heating device, wherein;

the flow switching device is operated such that thermal medium is circulated to the heating device in the warm-up operation of the fuel cell, and the thermal medium is circulated to the cooling device in a normal operation of the fuel cell, where the fuel cell normally performs power generation.

11. The fuel cell system according to claim 10, further comprising

a second thermal medium circulation device for controlling an amount of the thermal medium circulated into the bypass path.

12. The fuel cell system according to claim 11, further comprising:

a first temperature detection device for detecting a first temperature of a part of the fuel cell, that is collectively heated;

a second temperature detection device for detecting a second temperature of all the fuel cell; and

a controller for controlling operation of the fuel cell, wherein;

the controller controls the heating device to control a heating degree of the thermal medium using the heating device, controls the first thermal medium circulation device to control the amount of the thermal medium circulated into the thermal medium circulation path, and controls the second thermal medium circulation path to control the amount of the thermal medium circulated into the bypass path, based on the first temperature and the second temperature.

13. The fuel cell system according to claim 12, wherein:

the part of the fuel cell is collectively heated by circulating all of the thermal medium into the bypass path when the first temperature is lower than a first predetermined temperature; and

when the first temperature is higher than the first predetermined temperature, the amount of the thermal medium circulated into the other part of the fuel cell is adjusted so that the temperature of the thermal medium flowing into the fuel cell is controlled at a second predetermined temperature while the oxygen and the hydrogen are supplied to each cell.

14. The fuel cell system according to claim 12, wherein

the first and second temperature detection devices are constructed by a single detection sensor provided in the thermal medium circulation path at a downstream side of a join point between the thermal medium circulation path and the bypass path.

15. The fuel cell system according to claim 11, wherein:

the first thermal medium circulation device is operated to have a minimum flow amount of the thermal medium;

the second thermal medium circulation device is operated to have a maximum flow amount of the thermal medium; and

the minimum flow amount of the thermal medium circulated by the first thermal medium circulation device corresponds to the maximum flow amount of the thermal medium circulated by the second thermal medium circulation device.

16. The fuel cell system according to claim 2, wherein the heating device is disposed in the thermal medium circulation path between the thermal medium circulation device and the fuel cell.

17. The fuel cell system according to claim 16, wherein the heating device is disposed around a thermal medium inlet of the fuel cell, from which the thermal medium flows into the fuel cell.

18. The fuel cell system according to claim 16, further comprising

a heating bypass path part branched from the thermal medium circulation path and rejoined to the thermal medium circulation path at a rejoined point,

wherein the heating device is disposed in the heating bypass path part.

19. The fuel cell system according to claim 18, further comprising:

a flow adjustment device disposed at the rejoined point, for adjusting a flow amount of the thermal medium flowing through the heating device.

20. The fuel cell system according to claim 16, wherein the bypass path is joined to the thermal medium circulation path at an upstream side of the thermal medium circulation device on a thermal medium inlet side of the fuel cell.

21. The fuel cell system according to claim 20, wherein the bypass path is crossed with the thermal medium circulation path on a thermal medium outlet side of the fuel cell to have a crossed point, the fuel cell system further comprising:

a four-way valve disposed at the crossed point to switch a flow of the thermal medium from one of the thermal medium circulation path and the bypass path to one of the thermal medium circulation path and the bypass path.

22. The fuel cell system according to claim 2, wherein the bypass path has a diameter in a cross section, smaller than that of the thermal medium circulation path.

23. The fuel cell system according to claim 1, further comprising:

a thermal medium circulation path through which a thermal medium is circulated into each cell;

a first thermal medium circulation device for controlling an amount of the thermal medium circulated into the thermal medium circulation path;

a bypass path through which the thermal medium is circulated into only a part of each cell while bypassing the other part of each cell, the bypass path being provided in the thermal medium circulation path;

a heating device provided in the bypass path, for heating the thermal medium;

a second thermal medium circulation device provided in the bypass path, for circulating the thermal medium into the bypass path; and

a controller for controlling a flow amount of the thermal medium circulated into the thermal medium circulation path and a flow amount of the thermal medium circulating into the bypass path using the first and second thermal medium circulation devices.

24. The fuel cell system according to claim 1, further comprising

a thermal medium circulation path through which a thermal medium circulates into each cell;

a thermal medium circulation device disposed in the thermal medium circulation path, for circulating the thermal medium into the thermal medium circulation path; and

a heating device disposed to directly heat the part of each cell.

25. The fuel cell system according to claim 2, further comprising

an electrical heater which heats the thermal medium by converting electrical power generated in the fuel cell to a heat energy.

26. The fuel cell system according to claim 1, further comprising:

an oxygen feeder for supplying oxygen to an oxygen electrolyte of the fuel cell; and

a hydrogen feeder for supplying hydrogen to a hydrogen electrolyte of the fuel cell;

wherein;

when the part of each cell is collectively heated, a mixture gas of the oxygen and the hydrogen is supplied to at least one of the oxygen electrolyte and the hydrogen electrolyte.

27. The fuel cell system according to claim 1, wherein the fuel cell has therein a plurality of thermal medium passages through which a thermal medium flows in the fuel cell, the plurality of thermal medium passages being provided such that the thermal medium independently flows through the thermal medium passages.

28. The fuel cell system according to claim 1, wherein:

the fuel cell has therein a plurality of thermal medium passages through which a thermal medium flows in the fuel cell, the plurality of thermal medium passages being provided independently in parallel to each other on surfaces of the cells approximately perpendicular to a stack direction of the cells, the plurality of thermal medium passages being connected to each other in parallel in the stack direction.

29. The fuel cell system according to claim 28, wherein the thermal medium passages are arranged adjacent to each other in the stack direction.

30. The fuel cell system according to claim 29, wherein:

each thermal medium passages extends on each surface of the cells perpendicular to the stack direction; and

each thermal medium passages includes an inlet and outlet at its both ends, respectively.

31. The fuel cell system according to claim 27, further comprising:

a heating device for heating the thermal medium; and

a thermal medium circulation device for circulating the thermal medium into the thermal medium passages.

32. The fuel cell system according to claim 31, wherein:

the thermal medium circulation device includes an opening-closing device for opening the thermal medium passages one by one in order, and a circulation pump for circulating the thermal medium into the fuel cell; and

the thermal medium circulation device circulates the thermal medium into the fuel cell from a part of the fuel cell to all the fuel cell using the opening-closing device and the circulation pump.

33. The fuel cell system according to claim 32, wherein the opening-closing device is a valve.

34. The fuel cell system according to claim 32, wherein the opening-closing device is a pump.

35. The fuel cell system according to claim 32, wherein:

the thermal medium passages are provided on each surface of the cells independently from each other and in parallel to each other, to be perpendicular to a stack direction of the cells; and

the thermal medium passages are connected to each other in parallel in the stack direction.

36. The fuel cell system according to claim 31, further comprising:

a temperature detection device for detecting a temperature of the thermal medium flowing in the fuel cell; and

a controller for controlling the thermal medium circulation device based on the temperature of the thermal medium detected by the temperature detection device, wherein;

when the controller determines that the temperature of the thermal medium detected by the temperature detection device to be lower than a predetermined temperature, the controller outputs an operation signal to the thermal medium circulation device so as to circulate the thermal medium heated by the heating device into the fuel cell at a part thereof; and

when the controller determines that the temperature of the thermal medium detected by the temperature detection device to be increased higher than the predetermined temperature, the controller outputs an operation signal to the thermal medium circulation device so as to circulate the thermal medium heated by the heating device into the fuel cell from the part thereof to all thereof in accordance with a temperature increase of the thermal medium.

37. The fuel cell system according to claim 36, wherein

the fuel cell is disposed to generate electric power in the part of the fuel cell while the thermal medium circulates into the fuel cell at the part, and the generated electrical power being larger than electric power required for driving electric loads.

38. A fuel cell comprising:

a plurality of cells stacked in parallel in a stack direction;

a plurality of thermal medium passages through which a thermal medium is circulated into each cell, the plurality of thermal medium passages being provided on the cells such that the thermal medium flows through the thermal medium passages in parallel to be independent from each other.