REPEATING UNIT FOR A FUEL CELL STACK
A repeating unit ( 10 ) for a fuel cell stack comprises a gas conducting region ( 8 ) for conducting a first gas ( 12 ) to and along an active surface ( 14 ). A barrier ( 16 ) is located in the gas conducting region. The gas conducting region comprises, at least over the active surface, a plurality of channels ( 20, 22, 24, 26, 28, 30, 32, 34 ) for conducting the first gas along the active surface. At least a first channel ( 26 ) among the plurality of channels defines a first flow direction at a first point ( 46 ) located closest to the barrier and a second flow direction at a second point ( 48 ), wherein a first straight line ( 50 ) which extends through the first point ( 46 ) and is parallel to the first flow direction misses the barrier ( 16 ) while a second straight line ( 52 ) which extends through the second point ( 48 ) and is parallel to the second flow direction intersects the barrier. The barrier ( 16 ) can be located upstream or downstream of the active surface ( 14 ).
1 . A repeating unit for a fuel cell stack comprising a gas conducting region for conducting a first gas to and along an active surface, wherein a barrier is located in the gas conducting region and the gas conducting region comprises, at least across the active surface, a plurality of channels for conducting the first gas along the active surface, wherein at least a first channel among the plurality of channels defines a first flow direction at a first point located closest to the barrier and a second flow direction at a second point, wherein a first straight line which extends through the first point and is parallel to the first flow direction misses the barrier while a second straight line which extends through the second point and is parallel to the second flow direction intersects the barrier.
2 . The repeating unit according to claim 1 , wherein the barrier is located upstream or/and downstream of the active surface.
3 . The repeating unit according to claim 1 , wherein a cross sectional area of the first channel fully projects onto the barrier in a direction perpendicular to the cross sectional area.
4 . The repeating unit according to claim 1 , wherein at least the first channel extends beyond the active surface.
5 . The repeating unit according to claim 1 , wherein the active surface is a partial surface of a membrane electrode assembly and at least the first channel extends beyond the membrane electrode assembly.
6 . The repeating unit according to claim 1 , wherein the channels extend in a streamlined fashion.
7 . The repeating unit according to claim 1 , wherein the barrier comprises at least one section of a duct for conducting a second gas.
8 . The repeating unit according to claim 1 , wherein the active surface is an active surface of a cathode.
9 . The repeating unit according to claim 1 , wherein the repeating unit is designed for a uniform laminar flow of the first gas to the gas conducting region.
10 . The repeating unit according to claim 1 , wherein the channels are gas-tight with respect to each other.
11 . The repeating unit according to claim 1 , wherein the plurality of channels comprises a second channel and a third channel and a first edge of the active surface constitutes a closest edge of the active surface for the second channel as well as for the third channel, wherein the third channel extends closer to the first edge and has a smaller cross sectional area than the second channel.
12 . The repeating unit according to claim 1 , wherein the channels are formed so that in case of a uniform flow of the first gas to the gas conducting region the same amount of the first gas per time unit flows through each of the channels.
13 . The repeating unit according to claim 1 , wherein the channels are at least partly defined by a bipolar plate.
14 . A fuel cell stack comprising a repeating unit according to claim 1 .
15 . A vehicle with a fuel cell stack according to claim 14 .
16 . A combined heat and power generation equipment comprising a fuel cell stack according to claim 14 .