Method and apparatus for cold temperature operation of fuel cells utilizing hydrides having different heat capacities

• US 20020136937A1
• Filed: 03/26/2001
• Published: 09/26/2002
• Est. Priority Date: 03/26/2001
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Muthuswamy, Sivakumar, Pratt, Steven D., Kelley, Ronald J., Pennisi, Robert W.
• Granted Patent: US 6,586,124 B2
• Time in Patent Office: Days
• US Class Current: 429/17
• CPC Class Codes: H01M 8/04201 Reactant storage and supply, e.g. means for feeding, pipes
• CPC Class Codes: H01M 8/04208 Cartridges, cryogenic media or cryogenic reservoirs
• CPC Class Codes: H01M 8/04216 characterised by the choice for a specific material, e.g. carbon, hydride, absorbent
• CPC Class Codes: H01M 8/0432 Temperature; Ambient temperature
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An apparatus and method for temperature regulation of a fuel cell using differential heat capacity of the fuel storage media is disclosed. The method of regulating the temperature involves measuring the temperature of one or more fuel cells, comparing the temperature against target values, selecting a control method from a set of available control methods based on the result of comparison and using that control method to initiate and control a regulation cycle, and actuating a flow control means using the selected control method to alter the flow of fuel between one or more fuel storage containers, each containing fuel storage media which exhibit different enthalpies of formation and dissociation. The regulation process starts with measuring temperature (110) of a fuel cell system (100). The measured temperature is then compared (120) to a predetermined set of ideal target values designed to provide peak fuel cell performance. Following the comparison step, a control method (130) is selected from a list of available control methods. The control method has the necessary parameters and logic to define an fuel flow initiation process (140) which in turn actuates a flow control means (150). Actuation of the flow control means changes the temperature of the one or more fuel cells and alters its operating parameters (160).

Claims

1. A fuel cell for use in cold environments utilizing two hydrogen sources, each having different heat capacities, comprising:

a first hydrogen storage means having a first equilibrium pressure at temperature T;

a second hydrogen storage means having a second equilibrium pressure at temperature T;

a flow controlling means to regulate the flow of hydrogen between the first hydrogen storage means, the second hydrogen storage means, and the fuel cell;

a portion of the fuel cell in direct thermal contact with the second hydrogen storage means; and

wherein the first equilibrium pressure is greater than the second equilibrium pressure.

2. The fuel cell as described in claim 1, wherein the hydrogen storage means is a metal hydride, single walled nanotubes, chemical hydrides, or organic hydrides.

3. The fuel cell as described in claim 1, wherein direct thermal contact further comprises thermal contact through a thermally conductive medium disposed between the fuel cell and the first or second hydrogen storage means.

4. The fuel cell as described in claim 1, wherein direct thermal contact further comprises a convection means disposed on a major surface of the fuel cell and the first or second hydrogen storage means.

5. A fuel cell for use in cold environments utilizing two metal hydrides each having different heat capacities, comprising:

a first storage container containing a metal hydride having a first equilibrium pressure at temperature T;

a second storage container containing a metal hydride having a second equilibrium pressure at temperature T;

a flow control means for regulating the flow of hydrogen between the first storage container, the second storage container and the fuel cell;

the fuel cell in thermal contact with the second hydrogen container; and

wherein the first equilibrium pressure is greater than the second equilibrium pressure.

6. A method of operating a fuel cell in cold environments, comprising:

sensing the temperature of the fuel cell and comparing the sensed temperature to a set of predetermined parameters; and

actuating a flow control means as a result of the step of comparing so as to release hydrogen from a first hydrogen storage means into a second hydrogen storage means containing a metal hydride, to initiate an exothermic reaction in the metal hydride sufficient to increase the temperature of the second hydrogen storage means and sufficient to increase the temperature of the fuel cell.

7. The method as described in claim 6, further comprising transferring heat generated by the fuel cell to the second hydrogen storage means during operation of the fuel cell to cause the release of hydrogen from the metal hydride.

8. The method as described in claim 6, further comprising a second step of actuating the flow control means, after the step of releasing, wherein the flow control means terminates the release of hydrogen from the first hydrogen storage means into the second hydrogen storage means.

9. The method as described in claim 8, further comprising a third step of actuating the flow control means, after the second step of actuating, wherein hydrogen is transferred from the second hydrogen storage means into the first hydrogen storage means.

10. The method as described in claim 6, wherein the step of actuating further comprises releasing hydrogen from the second hydrogen storage means to the fuel cell.

11. The method as described in claim 6, wherein the step of actuating further comprises releasing hydrogen from the first hydrogen storage means to the fuel cell.

13. The method as described in claim 6, wherein heat generated by operation of the fuel cell is transferred to the second hydrogen storage means.

12. A method of operating a fuel cell, comprising opening a flow control valve so as to release hydrogen to the fuel cell and to release hydrogen from a first hydrogen storage means into a second hydrogen storage means containing a metal hydride, to initiate an exothermic reaction in the metal hydride sufficient to increase the temperature of the second hydrogen storage means and sufficient to increase the temperature of the fuel cell.