Patent ID: 6864005

Claim:
A solid polymer fuel cell system comprising a solid polymer fuel cell and an apparatus for humidifying a reactant gas supply stream, said fuel cell having a reactant gas inlet port and a reactant gas exhaust port, said humidifying apparatus comprising a membrane exchange humidifier comprising: (a) a supply stream chamber having an inlet and an outlet, said supply stream chamber inlet having a reactant gas supply fluidly connected thereto, said supply stream chamber outlet being fluidly connected to said fuel cell reactant gas inlet port; (b) an exhaust stream chamber having an inlet and an outlet, said exhaust stream chamber inlet fluidly connected to said fuel cell reactant gas exhaust port; and (c) a water permeable membrane separating said supply stream chamber and said exhaust stream chamber, whereby water is capable of being transferred across said water permeable membrane from a reactant gas exhaust stream to said reactant gas supply stream, said membrane comprising a microporous polymer and a hydrophilic additive, said membrane when dry being substantially permeable to at least one component of at least one of said reactant gas supply and exhaust streams.