Fuel cells evaporative reactant gas cooling and operational freeze prevention

A fuel cell power plant comprising:

• a stack (37, 120) of fuel cells, each fuel cell including an electrode assembly (72) including an electrolyte having cathode and anode catalysts disposed on opposite sides thereof, a fuel reactant gas flow field plate (75) having fuel reactant gas flow channels (74) extending from a first surface thereof, an oxidant reactant gas flow field plate (81) having oxidant reactant gas flow channels (82) extending from a first surface thereof, at least one of said flow field plates being porous and hydrophilic, and a water passageway (67;
• 78, 85;
• 78a, 85a) disposed on or near a second surface of said at least one flow field plate which is opposite to said first surface thereof;
• characterized by:
• said water passageways either being (a) dead-ended within the corresponding fuel cell or (b) vented (69, 89, 99, 145), said water passageway consisting of either (c) at least one fluid conduit (78, 85) in said at least one plate or (d) a material (78a, 85a) contiguous with substantially all of said second surface, said material being conductive, hydrophilic and permeable to water;
• and
• said fuel cell power plant further comprising:
• a condenser (59, 124) connected to a reactant gas exit of said at least one of said fuel cells, the condensate of said condenser in fluid communication with the water passageways of said fuel cells, whereby water migrates from said water passageways through each of said at least one hydrophilic, porous reactant gas flow field plates and is evaporated to cool said fuel cells.