| 摘要 |
PROBLEM TO BE SOLVED: To prevent a decrease in efficiency of converting electric power by a solid polymer type fuel cell by keeping metal ions in circulating water at low concentration which circulates through the solid polymer type fuel cell. SOLUTION: When the operation of a system is started, a timer 116 starts measuring the cumulative drive time of a fuel cell 40. When the cumulative drive time of the fuel cell 40 has reached a predetermined threshold, the drive of the fuel cell 40 is stopped and the supply of circulating water retained in a main tank 56 is switched from the fuel cell 40 to a water treatment device 84. Therefore, the water from which metal ions have been removed by the water treatment device 84 is returned into the main tank 56. Since the metal ions in the circulating water concentrate as the drive time of the fuel cell 40 increases, the electric power conversion efficiency of the fuel cell 40 can be kept at the normal level by setting as the threshold a time which is sufficiently shorter than the cumulative drive time required for the circuiting water to attain the concentration of the metal ions at which the electric power conversion efficiency is decreased. |
