Fuel cell system with liquid cooling device

A fuel cell system includes a fuel cell stack, an air supply system including a blower for driving the air to the fuel cell stack and an air humidifier for humidifying the air supplied to the fuel cell stack, a hydrogen supply system including a hydrogen storage and a pressure regulating device, and a hydrogen recirculator for receiving excessive hydrogen from the fuel cell stack and forcing the hydrogen back into the fuel cell stack in order to induce a hydrogen flow inside the fuel cell stack, a coolant circulation system supplying low temperature coolant to the fuel cell stack for absorbing heat from the fuel cell stack and including a coolant reservoir in which the coolant is stored, a pump driving the circulation of the coolant, a radiator for removing heat from the high temperature coolant and converting the high temperature coolant into the low temperature coolant. The coolant reservoir includes a ventilation device for removing air bubbles from the coolant. The coolant circulation system includes a heat exchanger for transferring heat from the high temperature coolant to the hydrogen storage. A control circuit electrically controls the flow and pressure regulating device, the blower, the pump and the fan.