Abstract: A method for starting a fuel cell in a fuel cell system, at temperatures below the freezing point of water, includes, in a first step, that the hydrogen concentration in the anode is increased; after which, in a second step, an anode pressure is increased for a fixed period of time, and while air is supplied to the cathode, the maximum possible current is drawn from the fuel cell, and after which, in a third step, the fuel cell is switched in a load-free manner and the anode pressure is reduced. After the third step, the second step and the third step are repeated successively until a sufficient performance of the fuel cell for its normal operation is reached.

Abstract: A method for preparing a fuel cell system in a vehicle for starting, for which purpose a starting preparation routine is carried out after the vehicle has been shut down depending on a temperature limit value. In the method, in the event that the fuel cell had not reached its normal operating temperature during the previous operation and a temperature falls below the predetermined temperature limit value, the fuel cell system is operated until it has reached its normal operating temperature and after which the starting preparation routine is subsequently carried out.

Abstract: The invention relates to a method for operating a fuel cell system, in particular a PEM fuel cell system, in which an QI anode gas is supplied to an anode (1) of a fuel cell via a supply path (2), and is fed back via a recirculation path (3) connected to the anode (1), wherein hydrogen is used as the anode gas. According to the invention, during the start up of the fuel cell system, the anode gas is supplied to a drying device (4), in particular an adsorber, via at least one normally open valve (8, 9, 10), and water is extracted from the anode gas using the drying device (4). The invention also relates to a fuel cell system, in particular a PEM fuel cell system, which is suitable for carrying out the method.

Abstract: A method for the start preparation of a fuel cell system in a vehicle having a fuel cell and a system bypass where an air flow is conveyed by parts of the fuel cell system in order to dry the fuel cell. In a first temporal phase of the method, a larger part of the air flow is led through the fuel cell and a smaller part of the air flow is led through the system bypass, after which, in a second temporal phase, a larger part of the air flow is led through the system bypass and a smaller part of the air flow is led through the fuel cell.

Abstract: A method for the start preparation of a fuel cell system in a vehicle having a fuel cell and a system bypass where an air flow is conveyed by parts of the fuel cell system in order to dry the fuel cell. In a first temporal phase of the method, a larger part of the air flow is led through the fuel cell and a smaller part of the air flow is led through the system bypass, after which, in a second temporal phase, a larger part of the air flow is led through the system bypass and a smaller part of the air flow is led through the fuel cell.

Abstract: A method for preparing a fuel cell system in a vehicle for starting, for which purpose a starting preparation routine is carried out after the vehicle has been shut down depending on a temperature limit value. In the method, in the event that the fuel cell had not reached its normal operating temperature during the previous operation and a temperature falls below the predetermined temperature limit value, the fuel cell system is operated until it has reached its normal operating temperature and after which the starting preparation routine is subsequently carried out.

Abstract: A method for starting a fuel cell in a fuel cell system, at temperatures below the freezing point of water, includes, in a first step, that the hydrogen concentration in the anode is increased; after which, in a second step, an anode pressure is increased for a fixed period of time, and while air is supplied to the cathode, the maximum possible current is drawn from the fuel cell, and after which, in a third step, the fuel cell is switched in a load-free manner and the anode pressure is reduced. After the third step, the second step and the third step are repeated successively until a sufficient performance of the fuel cell for its normal operation is reached.

Abstract: A method for flushing a fuel cell system during a power-down cycle includes conveying air by an air conveying device through a cathode space of a fuel cell and releasing the conveyed air through an exhaust air line. An outlet valve is cyclically closed and opened during the power-down cycle, where an opening duration depends on an amount of air that is conveyed and the outlet valve connects an anode discharge line to the exhaust air line. The conveyed air is guided from a delivery side of the air conveying device directly to the exhaust air line at least in part through a system bypass.

Abstract: A method for flushing a fuel cell system during a power-down cycle includes conveying air by an air conveying device through a cathode space of a fuel cell and releasing the conveyed air through an exhaust air line. An outlet valve is cyclically closed and opened during the power-down cycle, where an opening duration depends on an amount of air that is conveyed and the outlet valve connects an anode discharge line to the exhaust air line. The conveyed air is guided from a delivery side of the air conveying device directly to the exhaust air line at least in part through a system bypass.