Fuel cell device and method for cooling a fuel cell system

A method for cooling a fuel cell device in a vehicle including a fuel cell system, the fuel cell device including:

• a first cooling circuit including a fuel cell stack and having a first coolant medium flowing therethrough during operation for cooling the fuel cell stack;
• a second cooling circuit including a cooler that is configured to cool a second coolant medium flowing therethrough during operation for cooling an electronic unit and an energy storage of the vehicle, the second cooling circuit including a plurality of sub-circuits that are flow connected to one another including a cooler circuit, in which the second coolant medium is guided to and from the cooler, and a drive circuit, in which the second coolant medium is guided to and from the electronic unit and the energy storage, and wherein the drive circuit has a plurality of sub-circuits that are flow connected to one another including an electronic unit circuit for cooling the electronic unit, an energy storage circuit for cooling the energy storage, and a connection circuit that connects the electronic unit circuit and the energy storage circuit together such that the second coolant medium of the second cooling circuit flows through each of the cooler, the electronic unit and the energy storage during operation;
• and
• an air conditioning circuit to condition air of an interior of the vehicle,
• wherein the first cooling circuit and the second cooling circuit are thermally connected to one another by a first heat exchanger such that during operation heat from the fuel cell stack is transferred from the first coolant medium of the first cooling circuit to the second coolant medium of the second cooling circuit, which flows through each of the cooler, the electronic unit and the energy storage device during operation,
• wherein the second cooling circuit and the air conditioning circuit are thermally connected to one another by a second heat exchanger and configured such that heat absorbed from cooling the electronic unit and the energy storage during operation can be transferred from the second cooling circuit to the air conditioning circuit and used to heat the air of the interior of the vehicle,
• wherein the first cooling circuit and the air conditioning circuit are not thermally connected to one another,
• wherein the first cooling circuit is cooler-free such that the first cooling circuit is not fluidically coupled to the cooler of the second cooling circuit or any other cooler to preclude the first coolant medium flowing through the first cooling circuit during operation from flowing through any cooler,
• wherein the first cooling circuit lacks an electronic unit requiring heat generated thereby to be dissipated by the first cooling circuit,
• wherein the first cooling circuit consists only of the fuel cell stack, the first heat exchanger, and a pump to reduce installation space required for the first cooling circuit, including the fuel cell stack, and
• wherein the method comprises transferring waste heat produced in the fuel cell system from the first cooling circuit to the second cooling circuit by the first heat exchanger at a first temperature level and thereby heating the second coolant medium circulating in the second cooling circuit.