Appeal 2007-3580
Application 10/359,976
operating time” would not have been taught or suggested by the combination
of Chow’s reversing the flow direction of the fuel and oxidant in a fuel cell
with Carlstrom, Jr.’s fuel cell (Br. 6-7). Appellants argue that Chow
discloses that the flow directions of the fuel and oxidant streams are reversed
simultaneously, which means that the fuel and oxidant streams always flow
in opposite directions such that the claim recitation of flowing the oxidant
fuel streams “in the same direction . . . during a majority of operating time”
would not be met by the combination (Br. 5-6). Appellants argue that
because Chow’s streams always run in opposite directions, Chow teaches
away from “flowing the fuel and oxidant in the same direction a majority of
operating time” (Br. 7).
We have considered all of Appellants’ arguments and are unpersuaded
for the reasons below.
Carlstrom, Jr. discloses a method for removing water and controlling
concentration gradients in a fuel cell (Carlstrom, Jr., col. 2, ll. 25-37, 49-56).
Carlstrom, Jr. discloses that the pressure oscillations help to control the
concentration gradients in the fuel cell by wringing or removing the water
that blocks the diffusion paths for the fuel and oxidant (Carlstrom, Jr., col. 7,
ll. 1-17; col. 8, ll. 5-36). Carlstrom, Jr. further states that by oscillating the
pressure of the fuel and oxidant streams the power density of the fuel cell
may be improved (Carlstrom, Jr., col. 7, ll. 15-17). Appellants concede that
Carlstrom, Jr. discloses flowing the fuel and oxidant streams in the same
direction a majority of operating time (i.e., all the time) (Br. 5, ll. 7-8).
Chow discloses a method for managing water in fuel cells by
reversing the flow direction of the fuel and/or the oxidant stream(s) (Chow,
col. 1, ll. 27-30). Chow further discloses that the ionic membrane in the fuel
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