A method of maintaining health of a flow battery includes determining an average oxidation state of a common electrochemically active elemental specie in first and second fluid electrolytes on, respectively, a positive side and a negative side of an electrochemical cell of a flow battery, and adjusting the average oxidation state in response to the average oxidation state deviating from a predefined average oxidation state value.

The present disclosure relates to a valve opening/closing detection device for a fuel cell system and a method therefor and provides a valve opening/closing detection device for a fuel cell system, which detects a current (current waveform) supplied to a valve of the fuel cell system, determines a differential value of the current, detects opening/closing of the valve on the basis of a fluctuation range of the differential value, and thus may accurately detect an opening time point and a closing time point of the valve without a separate sensor, and a method therefor. To this end, the present disclosure may include a current sensor that measures a current applied to a valve, and a controller that determines a differential value of the current and detects opening/closing of the valve on the basis of a fluctuation range of the differential value.

A fuel cell system that includes a fuel cell module having first and second electrical supply terminals with an electrical output voltage applied thereto during operation of the fuel cell module. The electrical supply terminals are coupled to an electrical load, an air supply device that supplies air in an adjustable air quantity to the fuel cell module as one of the reactants for generating the output voltage, and a control device that controls an output power of the fuel cell module at the electrical supply terminals and adjusts the quantity of air supplied by the air supply device. The control device detects a load demand of the load and controls the output power of the fuel cell module in accordance with the detected load demand, to adjust and update the air quantity supplied by the air supply device in accordance with the detected load demand in air-ratio-controlled manner.

A plant includes a fuel supply line for supplying high-pressure fuel gas; and at least one expander disposed in the fuel supply line and configured to extract power from the high-pressure fuel gas by expanding the high-pressure fuel gas.

A system for estimating the amount of purge of a fuel cell is provided. The system includes a fuel cell that generates power by receiving hydrogen at an anode side and receives oxygen at a cathode side. A recirculation line is connected with the anode side of the fuel cell, and the gas included hydrogen therein is circulated in the recirculation line. A flow amount estimator estimates the flow amount of gas inside the recirculation line. A purge valve is positioned in the recirculation line and discharges the gas in the recirculation line to the outside when opened. A purge amount estimator estimates the amount of purge for each gas discharged through the purge valve by reflecting the flow amount of the gas estimated by the flow amount estimator.

A fuel cell system and method, the system including power generating fuel cells disposed in a stack, each power generating fuel cell including an anode, a cathode, and an electrolyte, a sensing fuel cell including an anode, a cathode, and an electrolyte, and a fuel processor configured to purify a fuel provided to the power generating fuel cells and the sensing fuel cell. The anode of the sensing fuel cell is thinner than the anodes of the power generating fuel cells.

A fuel cell system wherein the controller preliminarily stores a data group indicating a correlation between a voltage of the fuel cell and a concentration of impurity gas in the fuel gas; wherein the controller controls ON and OFF of the fuel gas supplier, wherein the controller operates the fuel gas supplier and determines whether or not the fuel cell voltage measured by the voltage sensor after an elapse of a predetermined time is less than a first threshold; and wherein, when the controller determines that the fuel cell voltage measured by the voltage sensor is less than the first threshold, the controller compares the voltage with the data group and determines that the concentration of the impurity gas in the fuel gas is higher than a predetermined concentration threshold.

A control unit estimates a discharged fuel gas amount, i.e., an amount of fuel gas discharged from the outlet of a cathode flow field, of a fuel exhaust gas introduced from a communication flow path to the inlet of the cathode flow field and then flowing through a cathode. The control unit calculates an oxygen-containing gas amount necessary for dilution at the time of discharge into the atmosphere, from the estimated discharged fuel gas amount, and sets a discharge amount of the air pump, based on the calculated oxygen-containing gas amount.

A fuel cell system (200) for providing electrical energy. The system (200) comprises a fuel cell stack (201), an anode subsystem (203) with a proportional valve (205) for dosing a volume of gas to be fed to the fuel cell stack (201), a purge valve (207) for discharging gas from the anode subsystem (203) into an exhaust-gas path (209) of the fuel cell system (200), and a control unit (211) for controlling the proportional valve (205) and the purge valve (207). The control unit (211) is configured to use an electrical control current that is fed to the proportional valve (205) to readjust for a purging operation to draw conclusions regarding a hydrogen concentration in a gas that is fed to the purge valve (207), wherein the control unit (211) is furthermore configured to adjust the fuel cell system (200) in a manner dependent on the determined hydrogen concentration.

An apparatus and method for controlling hydrogen purging are provided. The hydrogen purging control apparatus includes a purge valve that is disposed at an outlet on an anode side of a fuel cell stack and is configured to adjust an amount of emission of hydrogen containing impurities. Additionally, a controller is configured to adjust an opening and closing cycle of the purge valve based on a required output or an output current of the fuel cell stack.