DIRECT OXIDATION TYPE FUEL CELL SYSTEM
Disclosed is a fuel cell system comprising: a fuel cell including an anode and a cathode to which a water-soluble fuel and an oxidant are supplied, respectively, and a water-permeable electrolyte membrane interposed therebetween; a fuel tank; a first fuel supply unit which supplies an aqueous fuel solution to the anode; a second fuel supply unit which supplies the fuel to the first fuel supply unit; an oxidant supply unit which supplies an oxidant to the cathode; a temperature sensor which detects a temperature FT of the fuel cell; and a control unit which controls the first, second, and oxidant supply units, and the fuel cell whether to start or stop power generation. The control unit allows at least the first fuel supply unit to operate while the fuel cell is stopped from generating power, provided that the temperature FT of the fuel cell as such meets specific requirements.
1 . A fuel cell system comprising:
a fuel cell including: an anode to which a water-soluble fuel is supplied; a cathode to which an oxidant is supplied; and a water-permeable electrolyte membrane interposed between the anode and the cathode;
a fuel tank which stores the fuel;
a first fuel supply unit which supplies an aqueous fuel solution including the fuel and water, to the anode;
a second fuel supply unit which supplies the fuel stored in the fuel tank, to the first fuel supply unit;
an oxidant supply unit which supplies the oxidant to the cathode;
a temperature sensor which detects a temperature FT of the fuel cell; and
a control unit which controls the first, second, and oxidant supply units; and which controls the fuel cell whether to start or stop power generation,
the control unit allowing at least the first fuel supply unit to operate while the fuel cell is stopped from generating power, provided that the temperature FT of the fuel cell while being stopped from generating power, is equal to or lower than a first reference temperature relating to freezing of water and is also higher than a second reference temperature.
2 . The fuel cell system in accordance with claim 1 , wherein the first reference temperature is a first temperature T1 being higher than 0° C. and equal to or lower than 5° C.; and the second reference temperature is a third temperature T3 being higher than −5° C. and equal to or lower than −2° C.
3 . The fuel cell system in accordance with claim 2 , wherein the fuel includes methanol, and the first fuel supply unit supplies an aqueous methanol solution having a first concentration FC1 of 0.2 to 0.5 mol/L, to the anode.
4 . The fuel cell system in accordance with claim 1 , wherein the first reference temperature is a second temperature T2 being higher than − 2 ° C. and equal to or lower than 0° C.; and the second reference temperature is a third temperature T3 being higher than −5° C. and equal to or lower than −2° C., and the control unit allows both the first and second fuel supply units to operate, when the temperature FT is equal to or lower than the first reference temperature.
5 . The fuel cell system in accordance with claim 4 , wherein the fuel includes methanol, and the first fuel supply unit supplies an aqueous methanol solution having a second concentration FC2 of 0.5 to 4 mol/L, to the anode.
6 . The fuel cell system in accordance with claim 1 wherein the control unit allows the first, second, and oxidant supply units to operate, and the fuel cell to generate power, when the temperature FT is equal to or lower than the second reference temperature.