Flow control method of cooling medium in a fuel cell system, and fuel cell system

A fuel cell system, comprising:

• a fuel cell;
• an internal flow path of a cooling medium formed inside the fuel cell;
• an external flow path formed outside the fuel cell that forms a circulation flow path of the cooling medium by being connected to the internal flow path;
• and
• a control device programmed to:
• acquire a temperature of the fuel cell and identify a calorific value of the fuel cell,
• during a time period when the temperature of the fuel cell is lower than an end temperature that is predetermined as a temperature at the time of end of a warm-up operation, determine whether or not an inlet temperature, which is the temperature of the cooling medium at an inlet to the internal flow path within the circulation flow path, is equal to or above a lower-limit temperature of a temperature range in which generated water does not freeze within the fuel cell,
• when it is determined that the inlet temperature is equal to or above the lower-limit temperature during the time period, execute a first adjustment of a flow rate of the cooling medium in the circulation flow path so as to become greater than a normal flow rate corresponding to the calorific value of the fuel cell,
• when it is determined that the inlet temperature is not equal to or above the lower-limit temperature during the time period, execute a second adjustment of the flow rate of the cooling medium in the circulation flow path to be a flow rate that is less than the normal flow rate and that increases in accordance with an increase in the calorific value of the fuel cell, and
• adjust the flow rate of the cooling medium in the circulation flow path to be equal to the normal flow rate when the temperature of the fuel cell becomes equal to or above the end temperature, wherein the normal flow rate is a flow rate of the cooling medium determined based on the calorific value of the fuel cell.