Electrochemical cells utilizing Taylor Vortex Flows
Electrochemical cells ( 10 ), such as fuel cells ( 12 ) and fuel reformers ( 14 ), with rotating elements or electrodes ( 34, 24 ) that generate Taylor Vortex Flows ( 28, 50 ) and Circular Couette Flows ( 58 ) in fluids such as electrolytes and fuels are disclosed.
1. In a fuel cell ( 12 ) containing a fluid, an improvement comprising:
means ( 18 , 24 , 34 , 36 ) for creating Taylor Vortex Flows ( 28 , 50 ) in the fluid.
2. In the fuel cell ( 12 ) of claim 1 , a further improvement comprising:
means ( 18 , 24 , 34 , 36 , 50 ) for creating Circular Couette Flows ( 58 ) in the fluid.
3. In the fuel cell ( 12 ) of claim 1 , further improvement comprising:
one cylinder-like electrode ( 34 ) rotating relative to and separated by a fluid chamber ( 40 ) from another cylinder-like electrode ( 36 ).
4. In the fuel cell ( 12 ) of claim 1 , the improvement further comprising:
a fluid that is an electrolyte.
5. In the fuel cell ( 12 ) of claim 4 , the improvement further comprising:
protuberances ( 60 ) that extend from a surface layer ( 34 ′, 36 ′) of an electrode ( 34 , 36 ) into the Circular Couette Flows ( 58 ).
6. In the fuel cell ( 12 ) of claim 1 in which the means ( 34 , 36 ) for creating Taylor Vortex Flows ( 50 ) includes a first cylindrical-like electrode ( 36 ) enclosing a second cylindrical-like electrode ( 34 ) separated from the first by an electrolyte chamber ( 40 ) of gap distance d and length L and means for rotating one electrode with respect to the other at Ω radians per second, the improvement further comprising:
a. means for pumping electrolyte into and out of the chamber ( 40 ) at a total volumetric exchange rate of /U where U is the volume of electrolyte in the chamber and is the volumetric rate of flow into and out of the chamber; and
b. means for regulating the volumetric exchange rate of axial flow and Taylor Number T c of vortex flow ( 50 ) in the electrolyte so that—
T c =2 r 2 Ω 2 d 3 /ν 2 (1 +{r 1 /r 2 })>1,715( f{R a }), and; i.
R c ={Ωr 1 d/ν}≦ 10 4 ii.
where:
1. f{R a }=1.0+(0.297)(log 10 R a ) 4.04342 for R a ≧1.0
f{R a }=1.0 for 0≦R a ≦1.0,
2. r 1 =radius of the first electrode ( 36 ),
3. r 2 =radius of the second electrode ( 34 ),
4. d=r 1 −r 2 ,
5. ν=kinematic viscosity of electrolyte=μ(poise)/ρ(grams/cc.),
6. R a =(dL/ν)( /U), and
7. ( /U)≧0.
7. In the fuel cell ( 12 ) of claim 6 wherein RPM=30Ω/π, coordinates of d and RPM are within a Zone of Operable Parameters ( 70 ).
8. In the fuel cell ( 12 ) of claim 3 in which the improvement further comprises:
a. The first electrode ( 36 ) is reactive with a first chemical entering its pores from its first surface ( 44 ) to produce a first ion at its second surface layer ( 36 ′); and
b. The second electrode ( 34 ) is reactive with a second chemical entering its pores from its first surface ( 32 ) to produce a second ion at its second surface layer ( 34 ′) having a charge different from that of the first ion.
9. In the fuel cell ( 12 ) of claim 8 , the improvement further comprises:
means for controlling entry of a chemical into pores of an electrode surface layer ( 34 ′ or 36 ′) so that reaction-time:residence-time (t a ,/t r ,)≦1/10.
10. In the fuel cell ( 12 ) of claim 8 in which the means ( 34 , 36 ) for creating Taylor vortex flows ( 50 ) includes a first cylinder-like electrode ( 36 ) adjacent a second cylinder-like electrode ( 34 ) separated from the first by an electrolyte chamber ( 40 ) with—
i. gap distance d,
ii. gap length L, and
iii. means for rotating one electrode ( 36 or 34 ) with respect to the other electrode ( 34 or 36 ) at Ω radians per second, the improvement further comprising:
a. means for pumping electrolyte into and out of the chamber ( 40 ) at a total volumetric exchange rate of /U where U is the volume of electrolyte in the chamber and is the volumetric rate of flow into and out of the chamber ( 40 ); and
b. means for regulating the volumetric exchange rate of axial flow and Taylor Number T c of vortex flow in the electrolyte so that—
T c =2 r 2 Ω 2 d 3 /ν 2 (1 +{r 1 /r 2 })>1,715( f{R a }), and;
R c ={Ωr 1 d/ν}< 10 4
where:
1. f{R a }=1.0+(0.297)(log 10 R a ) 4.04342 for R a ≧1.0
f{R a }=1.0 for 0≦R a ≦1.0
2. r 1 =the largest radius of the first electrode,
3. r 2 =the smallest radius of the second electrode,
4. ν=kinematic viscosity of electrolyte=μ(poise)/ρ(grams/cc.),
5. R a =(dL/ν)( /U), and
6. /U≧0.
11. A fuel cell ( 10 ) comprising:
a. a first electrode ( 36 ) that is—
i. reactive with a first chemical entering its pores from its first surface ( 44 ) to produce a first ion at its second surface layer ( 36 ′);
b. a second electrode ( 34 ) that is—
i. reactive with a second chemical entering its pores from its first surface ( 32 ) to produce a second ion at its second surface ( 34 ′) having a charge different from that of the first ion, and
ii. within the first electrode ( 36 ) so that a chamber ( 40 ) is created between the second surface layers ( 36 ′ and 34 ′) of the two electrodes ( 36 and 34 );
c. a fluid electrolyte in the chamber ( 40 ); and
d. means for moving one electrode ( 36 or 34 ) with respect to the other electrode ( 34 or 36 ) to create Taylor Vortex Flows ( 50 ) in the fluid electrolyte
so as to generate a voltage across the electrodes ( 36 , 34 ) that are adapted to be connected to an external electrical circuit.
12. The fuel cell ( 10 ) of claim 11 wherein:
Circular Couette Flows ( 58 ) are created in the fluid electrolyte.
13. The fuel cell ( 10 ) of claim 11 wherein:
a. the first electrode ( 36 ) is cylinder-like and its second surface layer is its inner surface layer ( 36 ′); and
b. the second electrode ( 34 ) is cylinder-like and its second surface layer is its outer surface layer ( 34 ′) that is located substantially parallel to and within the first cylinder-like electrode ( 36 ) so as to create the chamber ( 40 ) for the electrolyte between the electrodes ( 36 and 34 ).
14. The fuel cell ( 10 ) of claim 11 comprising in addition:
means for controlling entry of a chemical into pores of an electrode layer ( 34 ′ or 36 ′) so that reaction-time:residence-time (t a ,/t r ,)≦1/10.
15. The fuel cell ( 10 ) of claim 11 wherein:
one chemical is a reductant and the other chemical is an oxidizer.
16. The fuel cell ( 10 ) of claim 12 Taylor Vortex Flows ( 50 ) wherein one of the electrodes ( 34 , 36 ) comprises:
a. a catalytic surface layer ( 34 ′, 36 ′), and
b. protuberances ( 60 ) that extend from the surface layer ( 34 ′, 36 ′) into the Circular Couette Flows ( 58 ).
17. The fuel cell ( 10 ) of claim 16 wherein one of the electrode catalytic surface layers ( 34 ′, 36 ′) comprises:
nanoporous metal foam ( 90 ).
18. The fuel cell ( 10 ) of claim 17 wherein the nanoporous metal foam ( 90 ) comprises:
pores ( 92 ) surrounded by scaffold struts ( 94 ).
19. The fuel cell ( 10 ) of claim 18 wherein the nanoporous metal foam ( 90 ) comprises:
organic catalyst particles that decorate the scaffold struts ( 94 ).
20. The fuel cell ( 10 ) of claim 18 wherein the nanoporous metal foam ( 90 ) comprises:
metal catalyst particles that decorate the scaffold struts ( 94 ).
21. The fuel cell ( 10 ) of claim 17 wherein the metal is selected from the:
Platinum Metals Group.
22. The fuel cell ( 10 ) of claim 21 wherein the metal comprises:
an alloy selected from the Platinum Metals Group.
23. The fuel cell ( 10 ) of claim 22 wherein the alloy comprises:
platinum.
24. The fuel cell ( 10 ) of claim 22 wherein the alloy comprises:
ruthenium.
25. The fuel cell ( 10 ) of claim 13 comprising in addition:
a fuel reformer ( 14 ) located with the second electrode ( 34 ) that generates hydrogen gas, which enters into fuel cell ( 12 ) by penetrating the second electrode ( 34 ).
26. A process for operating a fuel cell ( 10 ) to produce electricity for transmission to an external load comprising:
a. Pumping a reductant through a first electrode ( 34 ) of the cell ( 10 );
b. Pumping an oxidizer through a second electrode ( 36 ) of the cell ( 10 );
c. Pumping electrolyte into electrolyte chamber ( 40 ) of the cell ( 10 ) that is located between the electrodes ( 34 and 36 ); and
d. Rotating one electrode ( 34 or 36 ) with respect to the other electrode ( 36 or 34 ) at a rate sufficient to cause Taylor Vortex Flows ( 50 ) in the electrolyte chamber ( 40 ).
27. The process of claim 26 wherein:
the rotation of one electrode ( 34 or 36 ) with respect to the other electrode ( 34 or 36 ) is at a rate sufficient to cause electrolyte Circular Couette Flows in the electrolyte chamber ( 40 ).
28. The process of claim 27 wherein the reductant is:
hydrogen.
29. The process of claim 26 in which the cell ( 10 ) contains a fuel reformer chamber ( 26 ) between a fixed catalytic surface ( 18 ) and a rotating catalytic surface ( 24 ) and the process comprises an additional step of:
a. Pumping a fuel containing hydrogen atoms into the fuel reformer chamber ( 26 ); and
b. Rotating the reformer rotating catalytic surface ( 24 ) at a speed sufficient to cause—
i. fuel reformer Taylor Vortex Flows ( 28 ) in reformer chamber ( 26 ),
ii. fuel cell Taylor Vortex Flows ( 50 ) in the fuel cell electrolyte chamber ( 40 ), and
iii. H 2 from the fuel to penetrate through anode electrode ( 34 ) to creates H + ions that pass into the electrolyte chamber ( 40 ).
30. The process of claim 29 wherein:
Rotation of one electrode ( 34 or 36 ) with respect to the other electrode ( 36 or 34 ) is at a rate sufficient to cause Circular Couette Flows ( 58 ) in the electrolyte chamber ( 40 ).