The invention generally relates to controlling the temperature and relative humidity
of an incoming fuel cell reactant stream. In one aspect, a fuel cell system is
provided that includes a fuel cell having an anode inlet adapted to receive a flow
of anode gas from an anode inlet conduit, and a cathode inlet adapted to receive
a flow of cathode gas from a cathode inlet conduit. A first heat exchange surface
is adapted to contact the flow of anode gas within the anode inlet conduit, and
a second heat exchange surface adapted to contact the flow of cathode gas within
the cathode inlet conduit. A coolant system is adapted to circulate a coolant through
a coolant conduit. The coolant system is adapted to transfer heat from each of
the first and second heat exchange surfaces to the coolant.
