Water vapor transfer assembly

A water vapor transfer assembly for a fuel cell system includes at least one water vapor transfer device. The water vapor transfer device permits a transfer of water from a wet stream to a dry stream. The water vapor transfer device is disposed between a pair of end plates. The end plates each have a plurality of outwardly extending ribs. The water vapor transfer device and the end plates are disposed within a housing having a pair of wet stream apertures and a pair of dry stream apertures formed therein. The housing further includes a plurality of channels formed adjacent the dry stream apertures. The channels are in fluid communication with the wet stream apertures. The outwardly extending ribs of the end plates cooperate with the channels to define a tortuous bypass flow path between the wet stream apertures of the housing.