Residual water scavenging processing method in fuel cell system and fuel cell system

A fuel cell system comprising:

• a fuel cell;
• a fuel gas supply/discharge mechanism that supplies a reaction gas to the fuel cell and that discharges, from the fuel cell, an off-gas related to the reaction gas;
• a fuel gas discharge path;
• a purge valve configured to be arranged in the fuel gas discharge path to discharge water separated from the off-gas related to the reaction gas discharged from the fuel cell;
• an oxidizer gas supply/discharge mechanism that supplies an oxidizer gas to the fuel cell and that discharges, from the fuel cell, an off-gas related to the oxidizer gas;
• a first prediction portion that predicts, while the fuel cell system is operated, whether or not an outside temperature becomes equal to or less than a first predetermined temperature;
• a cathode-side scavenging processing portion that performs residual water scavenging processing on only the oxidizer gas supply/discharge mechanism among the fuel gas supply/discharge mechanism and the oxidizer gas supply/discharge mechanism when it is predicted that the outside temperature becomes equal to or less than the first predetermined temperature;
• an operation control portion that stops the operation of the fuel cell system after the residual water scavenging processing is performed on the oxidizer gas supply/discharge mechanism;
• a second prediction portion that predicts, after the stop of the operation of the fuel cell system, whether or not a temperature of the purge valve included in the fuel cell system becomes equal to or less than a second predetermined temperature;
• and
• an anode-side scavenging processing portion that performs the residual water scavenging processing on only the fuel gas supply/discharge mechanism among the fuel gas supply/discharge mechanism and the oxidizer gas supply/discharge mechanism when the second prediction portion predicts that the temperature of the purge valve becomes equal to or less than the second predetermined temperature and that fails to perform the residual water scavenging processing on the fuel gas supply discharge mechanism when the first prediction portion predicts that the outside temperature becomes equal to or less than the first predetermined temperature,
• wherein the residual water scavenging processing on only the fuel gas supply/discharge mechanism includes:
• opening the purge valve;
• and
• supplying a predetermined amount of fuel gas to the fuel cell.