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.

Systems and methods for operating a datacenter are disclosed. In at least one embodiment, a power delivery system includes one or more fuel cells to provide a source of electrical power for a datacenter, where waste heat produced by a fuel cell is to be captured and provided to an absorption chiller to produce a cooled liquid for use in a cooling system for this datacenter.

An ejector has a variable nozzle structure and is installed in a fuel cell recirculation line to supply new hydrogen and a recirculation gas. The ejector includes: a first housing having a first hole through which hydrogen is supplied and an orifice through which the hydrogen is discharged; a second housing disposed in the first housing and having a second hole into which the hydrogen passing through the first hole flows; and a poppet penetrating a third hole defined at one side of the second housing. The poppet is configured to adjust an area of a space opened by the orifice discharging the hydrogen. The hydrogen flowing into the second housing is discharged through a space between the other side opposite to the one side of the second housing and the poppet to move to the orifice.

A fuel cell system is provided having a fuel cell and a jet pump control valve unit connected to an anode chamber with an intake connection and a pressure connection. A fuel gas control valve connecting a fuel gas source and the jet pump has a valve seat with a first sealing surface and at least two through-flow channels, and a moveable valve body with a second sealing surface. The valve body can be moved into a blocking position and a through-flow position using a valve body actuator. The sealing surfaces rest on one another in a common sealing plane and form a seal in the blocking position. A stroke gap is formed between the sealing surfaces in the through-flow position. The first or second sealing surface is arranged on a raised sealing level. A volume flow of a drive jet can be controlled by the valve body actuator.

The present disclosure generally relates to systems and methods for determining, managing, and/or controlling excess hydrogen flow in a system comprising a fuel cell or fuel cell stack and ejector based on the internal state of the ejector.

The present disclosure generally relates to systems and methods for managing and/or excess hydrogen flow in a system comprising a fuel cell or fuel cell stack based on humidity measurements.

The present disclosure generally relates to systems and methods for determining, managing, and/or controlling excess hydrogen flow in a system comprising a fuel cell or fuel cell stack.

A fuel cell system includes: a stack generating electric power using reformed gas; a fuel processing device supplying reformed gas; a first gas passage connecting the stack and the fuel processing device, and carrying the reformed gas; a second gas passage connecting the stack and the fuel processing device and carrying an anode off gas (AOG) discharged from the stack; a buffer tank storing the AOG; a first buffer tank passage connecting the buffer tank and the second gas passage; a second buffer tank passage carrying the AOG stored in the buffer tank; a gas mixer connected to the second buffer tank passage and supplying the AOG stored in the buffer tank to the stack; and a controller controlling the gas mixer to supply the anode off gas stored in the buffer tank to the stack so as to preheat the stack or remove air in the stack.

A fuel gas supply system for a fuel cell includes an injector, an inlet pressure acquisition unit, a discharge valve, a hydrogen partial pressure acquisition unit, and a controller. The controller is configured to stop driving the injector when a hydrogen partial pressure reaches or exceeds a first upper limit value in a state where the injector is being driven, and start driving the injector when the hydrogen partial pressure falls to or below a first lower limit value in a state where the injector is stopped. The controller is configured to open the discharge valve when an inlet pressure reaches or exceeds a second upper limit value in a state where the discharge valve is closed, and close the discharge valve when the inlet pressure falls to or below a second lower limit value in a state where the discharge valve is open.

An apparatus for estimating an amount of condensed water in an anode of a fuel cell system includes: an initial anode water vapor amount calculation unit to calculate an initial amount of water vapor in the anode of a fuel cell upon startup, an anode diffusion amount calculation unit to calculate an amount of H.sub.2O diffused from a cathode to the anode, a purge amount calculation unit to calculate an amount of water vapor discharged upon gas purging in the anode, a recirculation amount calculation unit to calculate the amount of water vapor recirculated to the anode, and a condensed water amount determination and water level estimation unit to calculate the actual amount of water vapor in the anode based on values calculated using these units and to calculate the amount of condensed water in a water trap.