The present invention relates to a filter unit (100, 301) for filtering a fluid (105) for the operation of a fuel cell. The filter unit (100, 301) comprises at least one filter element (101) filled with a filter material (103) comprising cyclodextrin. The presented Invention also relates to a fuel cell system, to the use of cyclodextrin to filter a fluid for the operation of a fuel cell system, and to a method for operating a fuel cell system.

The invention relates to a method for detecting a leak in an energy converter system (1) containing a gas. A pressure regulator (3) is used to regulate a gas pressure in the energy converter system (1), and the pressure regulator (3) has a gas metering valve (4). The method has the following steps: a. measuring an inlet pressure (10) of the pressure regulator (3) and measuring an outlet pressure (12) of the pressure regulator (3), b. measuring an output variable (16) of the energy converter system (1) and calculating a gas requirement in the energy converter system (1) on the basis of the output variable (16) of the energy converter system (1), c. determining a first calculated flow (20) through the pressure regulator (3) on the basis of the measured inlet pressure (10) of the pressure regulator (3) and the measured outlet pressure (12) of the pressure regulator (3), d. determining a second calculated flow (22) through the pressure regulator (3) on the basis of the gas requirement, e. comparing the first calculated flow (20) with the second calculated flow (22) by generating a first comparison value (24) from the first calculated flow (20) and the second calculated flow (22), and f. determining a first threshold (26) and generating an error signal (32) if the value of the comparison value (24) is greater than the first threshold (26).

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.

A pulse hydrogen supply system for a proton exchange membrane fuel cell is provided. The system comprises a fuel cell, a high-pressure hydrogen bottle, a first pressure relief valve, an ejector, a steam-water separator, a first pressure control valve, a first pressure sensor, a high-pressure vessel, a first electromagnetic valve, a low-pressure vessel, a diaphragm pump, and a second electromagnetic valve. The high-pressure hydrogen bottle, the first pressure relief valve, the first pressure control valve, the ejector and the first pressure sensor are sequentially arranged on a gas inlet pipeline; the high-pressure vessel and the first electromagnetic valve are sequentially arranged on a branch pipeline; the second electromagnetic valve, the low-pressure vessel and the diaphragm pump are sequentially arranged on a first output loop; and the first output pipeline and the gas inlet pipeline form a loop.

A method of controlling a fuel cell device includes: a step of purging a hydrogen supply unit of a fuel electrode and purging a gas supply unit of an oxidant electrode when an operation of the fuel cell device ends; a step of measuring a voltage between the fuel electrode and the oxidant electrode and determining whether the voltage is greater than a predetermined threshold; a step of continuing power generation in the fuel cell device when the voltage is greater than the predetermined threshold; and a step of depressurizing the hydrogen supply unit and the gas supply unit when the voltage is equal to or less than the predetermined threshold.

A fuel cell system includes: a fuel cell in which an electrolyte membrane is inserted between a fuel electrode and an oxidant electrode, hydrogen is supplied to a hydrogen supply unit of the fuel electrode, and a gas containing oxygen is supplied to a gas supply unit of the oxidant electrode so that power is generated; a hydrogen coating unit disposed to cover the fuel cell and configured to be filled internally with hydrogen; and a hydrogen introduction unit configured to introduce hydrogen into the hydrogen coating unit.

A method for purging the hydrogen feed anode circuit of a fuel cell, whereby hydrogen is fed at a nominal pressure to the inlet of the cell, characterized in that at predetermined periodicity the following steps are repeated: instruction is given to open the hydrogen purge valve arranged on the outlet of the anode circuit; the pressure of hydrogen is measured at the inlet to the anode circuit of the cell, and the measured value is compared with a predetermined threshold pressure value; and the purge valve is closed when the measured pressure is equal to or lower than the predetermined threshold pressure value.

Methods and systems are provided for a redox flow battery system. In one example, a method of operating a redox flow battery system includes switching the redox flow battery system to an idle mode and completely draining electrolytes from one or more electrode compartments of the redox flow battery system. The one or more electrode compartments may be purged with a gas and refilled with fresh electrolytes.

A fuel cell system and the method of controlling the fuel cell system improve next-time startability in the following manner. Hydrogen, air, generation water, and the like that remain inside a large-sized fuel cell system needs to be removed after finishing operation of the large-sized fuel cell system, such as a fuel cell system for generating electric power. To the present end, when an air compressor needs to be operated, one fuel cell module is selected as a power supply module, and an air compressor is operated by the power supply module. Thus, durability of a fuel cell stack is improved, and at the same time, a constant amount of generated electricity necessary to restart the large-sized fuel cell system is ensured.

A fuel cell system includes a fuel cell generating electric power by a reaction between a fuel gas and an oxidant gas, an injector supplying the fuel gas to the fuel cell, a discharge line in which an off-gas discharged from the fuel cell flows, an ejector recirculating the off-gas flowing in the discharge line to the fuel cell using a flow of the fuel gas from the injector, a discharge valve discharging the off-gas flowing in the discharge line to the outside, and a control device controlling supply of the fuel gas by the injector and opening and closing of the discharge valve. When supply of the fuel gas by the injector is stopped, the control device opens the discharge valve while the off-gas is recirculated to the fuel cell and closes the discharge valve before supply of the fuel gas by the injector is restarted.