Hermetic high temperature dielectric and thermal expansion compensator
The present invention relates to a gas delivery device or conduit for a fuel cell stack. According to an embodiment, a gas delivery device for a fuel cell system includes a hollow ceramic element comprising a dielectric material and a hollow flexible element which compensates for differences in coefficients of thermal expansion between components of the fuel cell system. According to an embodiment, a fuel cell system includes a fuel cell stack or column, a gas delivery line fluidly connected to the stack or column, and a coefficient of thermal expansion compensator/isolator located in the gas delivery line. The coefficient of thermal expansion compensator/isolator includes a hollow ceramic element comprising a dielectric material and a hollow flexible element which compensates for differences in coefficients of thermal expansion between components of the fuel cell system.
1 . A gas delivery device for a fuel cell system, comprising:
a hollow ceramic element comprising a dielectric material; and
a hollow flexible element which compensates for differences in coefficients of thermal expansion between components of the fuel cell system.
2 . The gas delivery device of claim 1 , further comprising a first metal tube that is arranged between the ceramic element and the flexible element.
3 . The gas delivery device of claim 2 , wherein the ceramic element is joined to the first metal tube.
4 . The gas delivery device of claim 3 , wherein the ceramic element is brazed to the first metal tube.
5 . The gas delivery device of claim 2 , wherein the flexible element is a bellows.
6 . The gas delivery device of claim 3 , wherein:
the first metal tube includes a lip at an end of the first metal tube; and
the lip is arranged around an outer surface of the ceramic element so that the ceramic element is seated within the lip.
7 . The gas delivery device of claim 2 , wherein the ceramic element comprises alumina and the first metal tube comprises stainless steel or a nickel-based alloy.
8 . The gas delivery device of claim 2 , wherein the ceramic element comprises high purity alumina and the first metal tube comprises stainless steel.
9 . The gas delivery device of claim 2 , wherein the ceramic element comprises high purity alumina and the first metal tube comprises a Ni—Cr—W alloy or a Ni—Fe alloy.
10 . The gas delivery device of claim 1 , the ceramic element is joined to the flexible element.
11 . The gas delivery device of claim 10 , wherein the ceramic element is brazed to the flexible element which comprises a bellows.
12 . The gas delivery device of claim 2 , wherein the first metal tube includes a lip at a distal end of the first metal tube.
13 . The gas delivery device of claim 12 , wherein a wall thickness of the lip is 0.002″ to 0.015″ and a wall thickness of the ceramic element is 0.020″ to 0.100″.
14 . The gas delivery device of claim 13 , wherein the wall thickness of the lip is 0.004″ to 0.012″ and the wall thickness of the ceramic element is 0.025″ to 0.080″.
15 . The gas delivery device of claim 14 , wherein the wall thickness of the lip is 0.006″ to 0.010″ and the wall thickness of the ceramic element is 0.035″ to 0.050″.
16 . The gas delivery device of claim 2 , further comprising:
a second metal tube connected to the ceramic element; and
a third metal tube connected to the flexible element;
wherein:
the ceramic element is located between the first metal tube and the second metal tube; and
the flexible element is located between the second metal tube and third metal tube.
17 . The gas delivery device of claim 16 , wherein:
the second metal tube is fluidly connected to a gas source;
the third tube is fluidly connected to a fuel cell stack or column; and
the flexible element comprises a bellows.
18 . A fuel cell system, comprising:
a fuel cell stack or column;
a gas delivery line fluidly connected to the stack or column; and
a coefficient of thermal expansion compensator/isolator located in the gas delivery line, wherein the coefficient of thermal expansion compensator/isolator comprises:
a hollow ceramic element comprising a dielectric material; and
a hollow flexible element which compensates for differences in coefficients of thermal expansion between components of the fuel cell system.
19 . A gas delivery line for a fuel cell system, comprising:
a means for electrically isolating components of a fuel cell stack or column from a balance of gas delivery plumbing for a fuel cell stack or column; and
a means for compensating for differences in coefficients of thermal expansion between components of the fuel cell system.
20 . A fuel cell system, comprising:
a fuel cell stack or column;
the gas delivery line of claim 19 .