Enclosed fuel cell stack row
Solid polymer electrolyte fuel cell stacks require a significant nominal compressive loading for proper operation and sealing. This loading is typically provided using relatively thick end plates and tight straps. In certain fuel cell applications, one or more solid polymer electrolyte fuel cell stacks are secured in larger enclosures (e.g. for isolation and crashworthiness in automotive applications). The enclosures however can themselves be sturdy enough to provide the necessary loading on the fuel cell stacks within. The present invention takes advantage of that to allow for use of thinner end plates and/or weaker straps which would otherwise be insufficient for use.
1. An enclosed fuel cell stack row comprising:
at least one solid polymer electrolyte fuel cell stack; and
an enclosure;
wherein each of the at least one solid polymer electrolyte fuel cell stack comprises:
a series stack of a plurality of solid polymer electrolyte fuel cells;
a pair of end plates at either end of the series stack; and
at least one stack strap encircling the series stack and the end plates;
wherein each of the end plates applies compressive force to each respective end of the series stack at a nominal loading for operating the at least one solid polymer electrolyte fuel cell stack, and wherein the enclosure is capable of supporting the nominal loading for each of the at least one solid polymer electrolyte fuel cell stack in the fuel cell stack row;
wherein each aligned one of the at least one solid polymer electrolyte fuel cell stack is compressed to a fixed loading less than the nominal loading by a combination of the end plates and the at least one stack strap in each of the at least one solid polymer electrolyte fuel cell stack, wherein the combination is insufficient on its own to provide the nominal loading for each of the at least one solid polymer electrolyte fuel cell stack.
2. The enclosed fuel cell stack row of claim 1 , wherein a deflection of the end plates on their own under the nominal loading on the series stack exceeds 1.5 mm, and wherein the enclosure supports the end plates so as to provide the nominal loading on the series stack.
3. The enclosed fuel cell stack row of claim 1 , wherein an elongation of the at least one strap on its own under the nominal loading on the series stack exceeds 0.5 mm, and wherein the enclosure supports the end plates so as to maintain the nominal loading on the series stack.
4. The enclosed fuel cell stack row of claim 2 , wherein one of the end plates is made of thermoplastic material and has a thickness less than about 4 cm.
5. The enclosed fuel cell stack row of claim 1 , wherein the nominal loading for operating the at least one solid polymer electrolyte fuel cell stack is greater than or about 27 kN.