METHODS AND APPARATUS FOR IMPROVING THE COLD STARTING CAPABILITY OF A FUEL CELL

• US 20070072016A1
• Filed: 09/20/2006
• Published: 03/29/2007
• Est. Priority Date: 03/28/2001
• Status: Abandoned Application

• Current Assignee: Ford Motor Company, Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Ford Motor Company, Daimler AG (Mercedes-Benz Group AG)
• Inventors: Haas, Herwig, Atbi, Abderrahmane, Jia, NengYou, Geest, Marian, St-Pierre, Jean
• Application Number:
  US11/533,702
• Publication Number:
  US 20070072016A1
• Time in Patent Office: Days
• US Class Current: 429/413
• CPC Class Codes: H01M 8/0258 characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• CPC Class Codes: H01M 8/0267 having heating or cooling means, e.g. heaters or coolant flow channels
• CPC Class Codes: H01M 8/0271 Sealing or supporting means around electrodes, matrices or membranes
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04156 with product water removal
• CPC Class Codes: H01M 8/04228 during shut-down
• CPC Class Codes: H01M 8/04303 applied during shut-down
• CPC Class Codes: H01M 8/04328 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04335 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04343 of anode exhausts
• CPC Class Codes: H01M 8/0435 of cathode exhausts
• CPC Class Codes: H01M 8/04358 of the coolant
• CPC Class Codes: H01M 8/04388 of anode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04395 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04507 of cathode reactants at the inlet or inside the fuel cell
• CPC Class Codes: H01M 8/04514 of anode exhausts
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04649 of fuel cell stacks
• CPC Class Codes: H01M 8/04828 Humidity; Water content
• CPC Class Codes: H01M 8/04955 : Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/04992 : characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence
• CPC Class Codes: H01M 8/1007 : with both reactants being gaseous or vaporised H01M8/12 takes precedence
• CPC Class Codes: H01M 8/241 : with solid or matrix-supported electrolytes
• CPC Class Codes: H01M 8/2465 : Details of groupings of fuel cells
• CPC Class Codes: H01M 8/2483 : characterised by internal manifolds
• CPC Class Codes: Y02E 60/50 : Fuel cells

Abstract

Apparatus and methods of ceasing operation of an electric power generating system improve the cold starting capability of the system. The system comprises a fuel cell stack connectable to an external circuit for supplying power to the external circuit. The stack comprises at least one solid polymer fuel cell, and the system further comprises a fuel passage for directing a fuel stream through the stack and an oxidant passage for directing an oxidant stream through the stack, a sensor assembly connected to the stack for monitoring a parameter indicative of stack performance, a controller for controlling at least one stack operating parameter, and a control system communicative with the sensor assembly and stack operating parameter controller. The method comprises adjusting at least one stack operating parameter to cause the stack to operate under a drying condition that causes a net outflux of water from the stack, operating the stack under the drying condition until the water content in the stack has been reduced, and interrupting supply of power from the stack to the external circuit.

Claims

1-34. -34. (canceled)

35. An electric power generation system comprising:

(a) a fuel cell stack connectable to an external circuit for supplying electric power to the external circuit, the stack comprising at least one solid polymer fuel cell and fluid flow passages through the stack;

(b) a sensor assembly connected to the stack for monitoring at least one parameter indicative of stack performance;

(c) a controller for controlling at least one stack operating parameter; and

(d) a control system communicative with the sensor assembly and the stack operating parameter controller, such that upon receipt of a shut down instruction from the control system, the stack operating parameter controller is operable to adjust at least one stack operating parameter such that the stack operates in a drying condition that causes a net outflux of water from the stack, until the water content in the stack has been reduced.

36. The electric power generation system of claim 35 wherein the sensor assembly comprises a sensor for monitoring a parameter indicative of stack performance selected from the group consisting of:

the resistance of at least one fuel cell in the stack,

the impedance of at least one fuel cell in the stack, and

the voltage of at least one fuel cell in the stack.

37. The electric power generation system of claim 35 wherein the sensor assembly comprises at least one sensor for monitoring the at least one stack operating parameter.

38. The electric power generation system of claim 37 wherein the sensor assembly comprises a sensor for monitoring a stack operating parameter selected from the group consisting of:

the relative humidity of at least one of the oxidant and fuel streams;

the stoichiometry of at least one of the oxidant and fuel streams;

the flow rate of at least one of the oxidant and fuel streams;

the pressure of at least one of the oxidant and fuel streams; and

the stack temperature.

39. The electric power generation system of claim 35 wherein the controller comprises apparatus to control at least one stack operating parameter selected from the group consisting of:

the relative humidity of at least one of the oxidant and fuel streams;

the stoichiometry of at least one of the oxidant and fuel streams;

the flow rate of at least one of the oxidant and fuel streams;

the pressure of at least one of the oxidant and fuel streams; and

the stack temperature.

40. The electric power generation system of claim 35 wherein the control system comprises a microcontroller.

41. The electric power generation system of claim 39 further comprising a humidifier for humidifying at least one of a fuel or oxidant stream supplied to the stack during normal operation, and wherein the relative humidity control apparatus comprises a humidifier bypass system having at least one bypass conduit for directing at least some of at least one of fuel or oxidant to the stack in fluid isolation from the humidifier.

42. The electric power generation system of claim 41 wherein upon receipt of a shut down instruction from the control system, the humidifier bypass system directs at least some of the oxidant or fuel streams through the associated bypass conduit.

43. The electric power generation system of claim 42 wherein the bypass conduit comprises an inlet end connected to one of the reactant stream passages at a location upstream of the humidifier, and an outlet end connected to the same reactant stream passage at a location downstream of the humidifier.

44. The electric power generation system of claim 42 wherein the bypass conduit comprises an inlet end connectable to a reactant supply, and an outlet end connected to one of the reactant stream inlet passages at a location downstream of the humidifier.

45. The electric power generation system of claim 42 wherein the humidifier bypass system comprises a bypass inlet valve connected to one of the reactant passages at a location upstream of the humidifier, and a bypass outlet valve connected to the same reactant passage at a location downstream of the humidifier, and wherein the bypass conduit is connected to the bypass inlet and outlet valves.

46. The electric power generation system of claim 39 wherein the oxidant stoichiometry control apparatus comprises a compressor connected to the oxidant inlet passage.

47. The electric power generation system of claim 39 wherein the pressure control apparatus comprises a pressure regulator on at least one of an oxidant and fuel passage.

48. The electric power generation system of claim 39 wherein the stack temperature control apparatus comprises a coolant system having a coolant passage through the stack and a coolant pump communicative with the control system.

49. The electric power generation system of claim 35 wherein the control system is operable such that the drying operation is discontinued after the parameter indicative of stack performance measured by the sensor assembly reaches a threshold value.