Patent ID: 7776482

Claim:
A direct oxidation fuel cell (DOFC) system, comprising: (a) at least one fuel cell assembly including a cathode and an anode with an electrolyte positioned therebetween, said at least one fuel cell assembly adapted for performing selected electrochemical reactions at said anode and cathode; (b) a source of liquid fuel in fluid communication with an inlet of said anode; (c) an oxidant supply in fluid communication with an inlet of said cathode; (d) a liquid/gas (L/G) separator in fluid communication with outlets of each of said anode and cathode for: (1) receiving unreacted fuel and liquid and gaseous products of said selected electrochemical reactions at said cathode and anode, and (2) supplying said unreacted fuel and liquid product to said inlet of said anode; (e) an electronic control unit (ECU) comprising a stored data table correlating the current density equivalent of the liquid fuel crossover rate with output current density; and (f) a control system comprising the ECU, wherein, the control system is programmed to determine a fuel efficiency value of said DOFC system during operation using the stored data table and programmed to determine and control the oxidant stoichiometry of said DOFC system at an appropriate value in response to the determined fuel efficiency value.