Fuel cell cooling and recirculation system

A fuel cell system comprising:

• a fuel cell stack including an anode and a cathode;
• means for supplying a hydrogen-containing fuel adjacent said anode;
• means for supplying an oxygen-containing oxidant adjacent said cathode in an amount in excess of the stoichiometric amount relative to said fuel;
• means for conducting reaction products including excess oxidant and water vapor from said cathode;
• means for cooling and flowing said products through a flow constriction, said cooling and flow means including a liquid coolant injector;
• means disposed downstream of said flow constriction for separating said coolant, oxidant and water into a vaporous portion and a liquid portion, said separating means including an outlet for said vapor portion;
• and
• a conduit interconnecting said outlet and said cathode;
• said cooling and flow means providing sufficient pressure head to flow said vaporous portion through said interconnecting conduit, adjacent said cathode, and back to said flow constriction;
• and
• means for conducting said liquid portion through a heat exchanger and to said injector.

A method of operating a fuel cell system including a fuel cell stack having an anode and a cathode, comprising:

• supplying a hydrogen-containing fuel to said anode;
• supplying an oxygen-containing oxidant to said cathode in an amount in excess of the stoichiometric amount relative to said fuel;
• conducting reaction products including excess oxidant and water from said cathode;
• injecting a liquid coolant through a flow constriction in fluid communication with said reaction products whereby said coolant and reaction products are mixed, flow through said constriction, and said reaction products are cooled;
• separating said mixed reaction products and coolant into a vaporous portion and a liquid portion;
• and
• conducting said vaporous portion to said cathode;
• said step of flowing said products through a flow constriction including providing sufficient pressure head to flow said vaporous portion to said cathode.