Method of Controlling and Maximizing the Electric Efficiency and the Power Output of a Fuel Cell

A method of evaluating the electric efficiency of a fuel cell comprising the following steps:

• arranging a circuit including a fuel cell and a resistor electrically connected with said fuel cell,
• supplying said circuit with reagents having known dilution, and with determined dilution gradient along the overall electrodes active surface;
• evaluating a reference electric efficiency for the fuel cell supplied with said reagents having known dilution;
• evaluating the reference voltage drop across the resistor;
• changing the dilution of at least one reagent;
• changing the resistance of the resistor until a voltage drop across the resistor equal to the reference voltage drop is obtained;
• and
• evaluating the electric efficiency of the fuel cell on the base of the reference electric efficiency of the fuel cell, of the dilution of the reagents to be fed to the fuel cell before and after changing the dilution of the at least one reagent, and on the base of the ratio of resistor resistances before and after changing the resistance of the resistor.

A method of evaluating the electric efficiency of a fuel cell comprising the following steps:

• arranging a first fuel cell, whose electric efficiency is to be determined, in electrical connection with a first resistor of known resistance value, thereby obtaining a first circuit;
• arranging a second circuit including a second fuel cell identical to the first fuel cell, and a second resistor electrically connected with the second fuel cell,
• supplying the first and the second circuit with reagents having a known dilution(s), and with determined dilution gradient along the overall electrodes active surface;
• evaluating the electric efficiency of the second fuel cell on the base of its respective reagent dilution(s);
• evaluating the voltage drop across the resistor of the first and of the second circuit;
• keeping the second resistor (R1) at a predetermined value and varying the first resistor (Rλ) until the same voltage drop across the resistor of the first and the second circuit is obtained, thereby determining a first resistor value;
• and
• evaluating the electric efficiency of the first fuel cell on the base of the electric efficiency of the second fuel cell, of the reagent dilution(s) to be fed to the fuel cell, and on the base of the ratio of first resistor value to second predetermined resistor value.

A fuel cell suitable for obtaining an electric power output comprising:

• a casing in which an intermediate space is delimited between a cathodic space and an anodic space;
• at least one electrolytic material located in said intermediate space;
• a positive electrode (5) electrically connected to the end of said electrolytic material at the cathodic space (3);
• a negative electrode (6) electrically connected to the end of the electrolytic material at the anodic space (4);
• an oxidant inlet mixture in fluid communication with said cathodic space (3);
• and
• a reducing inlet mixture in fluid communication with said anodic space (4),
• characterized in that it comprises:
• means for checking and adjusting the dilution gradient of the reagents along the overall electrodes active surface, i.e. the variation of reagent dilutions among different parts of the electrodes active surface, and
• control means of the electric efficiency of said fuel cell including means suitable for checking and/or adjusting the current density produced in the fuel cell per unit of active surface area.