Patent ID: 8343677

Claim:
A method of starting a fuel cell system that comprises: a polymer electrolyte membrane fuel cell (PEMFC) stack comprising unit cells and coolant plates to cool the unit cells; a first flow line that passes through gravitationally upper parts of the cooling plates; a second flow line that passes through gravitationally lower parts of the cooling plates; a heat exchanger and a coolant reservoir sequentially connected between an outlet of the first flow line and an inlet of the second flow line; a first valve installed between the coolant reservoir and the inlet of the second flow line; a by-pass line that is connected between a second valve and an inlet of the first flow line, the second valve selectively controlling a coolant flow from the coolant reservoir to the second flow line or the by-pass line; a heating element installed on the bypass line to heat coolant in the by-pass line; the method comprising: closing the first valve and controlling the second valve so that coolant can flow from the second flow line to the by-pass line through the second valve, and the coolant in the coolant reservoir cannot flow to the second flow line or the by-pass line; and increasing the temperature of the PEMFC stack by heating the coolant in the by-pass line using the heating element and flowing the coolant from the by-pass line to sequentially pass through the first flow line and the PEMFC stack, wherein the coolant passes through the second flow line, the coolant plates, the first flow line, the heat exchanger, and the coolant reservoir in this order during a normal operation of the fuel cell system, and the coolant passes through the by-pass line, the first flow line, the cooling plates, and the second flow line in this order during a starting operation of the fuel cell system.