Hydrogen-processing assemblies and hydrogen-producing systems and fuel cell systems including the same

1. A hydrogen-purification assembly configured to receive a mixed gas stream and to produce a product hydrogen stream and a byproduct stream therefrom, the hydrogen-purification assembly comprising:

an enclosure including an internal surface and defining an internal volume, wherein the internal volume includes a mixed gas region and a permeate region, and further wherein the internal surface defines at least a portion of the permeate region;

a hydrogen-separation assembly positioned within the internal volume in a spaced-apart relation to at least a portion of the internal surface, wherein the hydrogen-separation assembly includes a plurality of generally planar hydrogen-selective membranes, wherein the hydrogen-separation assembly defines the mixed gas region and isolates the mixed gas region from the internal surface of the enclosure, and further wherein the product hydrogen stream is formed from a portion of the mixed gas stream that passes through at least one of the plurality of generally planar hydrogen-selective membranes and from the mixed gas region to the permeate region;

a mixed gas stream input port configured to provide a mixed gas inlet for delivery of the mixed gas stream to the mixed gas region of the hydrogen-purification assembly;

a byproduct stream output port configured to provide a byproduct outlet for withdrawal of the byproduct stream from the mixed gas region of the hydrogen-purification assembly; and

a product hydrogen stream output port configured to provide a hydrogen outlet for withdrawal of the product hydrogen stream from the permeate region of the hydrogen-purification assembly.

2. The hydrogen-purification assembly of claim 1 , wherein the hydrogen-separation assembly entirely defines the mixed gas region.

3. The hydrogen-purification assembly of claim 1 , wherein the hydrogen-separation assembly is contained entirely within the internal volume.

4. The hydrogen-purification assembly of claim 1 , wherein the hydrogen-separation assembly includes an external surface including a plurality of sides, and further wherein each of the plurality of sides is contained within the internal volume.

5. The hydrogen-purification assembly of claim 4 , wherein at least two of the plurality of sides is in fluid communication with the permeate region.

6. The hydrogen-purification assembly of claim 4 , wherein at least two of the plurality of sides define at least a portion of the permeate region.

7. The hydrogen-purification assembly of claim 1 , wherein the internal surface is not in fluid communication with the mixed gas stream.

8. The hydrogen-purification assembly of claim 1 , wherein the mixed gas stream includes hydrogen gas and other gasses, wherein the product hydrogen stream includes at least one of a greater concentration of hydrogen gas and a lower concentration of the other gasses than the mixed gas stream, and further wherein the byproduct stream includes at least a substantial portion of the other gasses.

9. The hydrogen-purification assembly of claim 1 , wherein the permeate region is defined by a majority of the internal surface of the enclosure.

10. The hydrogen-purification assembly of claim 9 , wherein the permeate region is defined by substantially all of the internal surface of the enclosure.

11. The hydrogen-purification assembly of claim 1 , wherein the plurality of hydrogen-selective membranes includes palladium.

12. The hydrogen-purification assembly of claim 1 , wherein the plurality of hydrogen-selective membranes includes at least one pair of generally opposed hydrogen-selective membranes, wherein each of the pair of generally opposed hydrogen-selective membranes includes a mixed gas surface configured to be in fluid communication with the mixed gas stream and a permeate surface configured to be in fluid communication with the product hydrogen stream, wherein the permeate surfaces of the pair of generally opposed hydrogen-selective membranes define at least a portion of the permeate region, and further wherein the mixed gas surfaces of the pair of generally opposed hydrogen-selective membranes define at least a portion of the mixed gas region.

13. The hydrogen-purification assembly of claim 12 , wherein the mixed gas surfaces of the plurality of hydrogen-selective membranes define a majority of the mixed gas region.

14. The hydrogen-purification assembly of claim 12 , wherein the mixed gas surfaces of the plurality of hydrogen-selective membranes define substantially all of the mixed gas region.

15. The hydrogen-purification assembly of claim 12 , wherein the hydrogen-separation assembly does not include a seal extending between the permeate surfaces of the pair of generally opposed hydrogen-selective membranes.