Provided is an apparatus for soft-sensing a fuel cell system. The apparatus includes: a connecting unit detachable from a control unit for being connected to an outside of a stationary fuel cell system; a collecting unit connected to the connecting unit and receiving data of the stationary fuel cell system; a quality variable predicting unit connected to the collecting unit and predicting a quality variable of the stationary fuel cell system based on the received data; and a monitoring unit connected to the quality variable predicting unit and outputting the predicted quality variable. The quality variable predicting unit is configured to predict the quality variable predictable including at least any one of a concentration of carbon monoxide in a reformed gas at a rear end of a fuel converting system, and a concentration of methane in the reformed gas at the rear end of the fuel converting system.

Disclosed herein are methods and systems that relate to an on-line monitoring of a process/system by controlling rate of oxidation of metal ions at an anode in an anode electrolyte of an electrochemical process and controlling rate of reduction of the metal ions in a catalysis process to achieve steady state.

To provide a technique to suppress an excessive rise of pressure between two pressure reducing valves if the amount of fuel gas consumed by a fuel cell stack decreases. A fuel gas supply apparatus comprises: a gas passage in which fuel gas to be supplied to a fuel cell stack flows; a first pressure reducing valve provided to the gas passage; a second pressure reducing valve provided to the gas passage and disposed at a downstream side of the first pressure reducing valve; a setting module that sets a value of target pressure at a downstream side of the second pressure reducing valve, to a value depending on a consumed amount of fuel gas consumed by the fuel cell stack; and a modifying module that, if the consumed amount decreases by a prescribed amount or more, modifies the value of target pressure of the second pressure reducing valve to a value greater than a corresponding value that corresponds to the consumed amount subsequent to the decrease.

One embodiment provides a method for predicting maintenance of a redox flow battery, the method including: receiving, from a plurality of sensors, data regarding characteristics of the redox flow battery; weighting, using a processor, each of the characteristics to form an estimated state parameter for the redox flow battery; and determining, using the processor, a maintenance action for the redox flow battery using the estimated state parameter. Other aspects are described and claimed.

A method for performing one or more proactive remedial actions to prevent anode flow-field flooding in an anode side of a fuel cell stack at low stack current density. The method includes identifying one or more trigger conditions that could cause the anode flow-field to flood with water, and performing the one or more proactive remedial actions in response to the identified trigger conditions that removes water from the anode side flow-field prior to the anode flooding occurring.

A method is provided for restoring an electrolyte of vanadium (V) redox flow battery (VRFB). Electrolyte data of an original system are analyzed in advance. A reusable positive electrode is further equipped with a V electrolyte. A reductant for a stack of VRFB is used in coordination as an electrolysis device. After a long-term reaction with a VRFB having a high valence (greater than 3.5), an electrolyte at the positive electrode is directed out to a negative electrode of the electrolysis device; and, then, electrolysis is processed after accurate calculation. In the end, the internal fluid balancing method of the original system is combined. Thus, a harmless and quick valence restoration is processed for the electrolyte of the original system, which is a final resort for the restoration of V electrolyte.

A device for decreasing hydrogen concentration of a fuel cell system is installed in an exhaust system of a fuel cell system so as to discharge exhaust gas including hydrogen and air from fuel cells to the atmosphere through an exhaust line. The device includes: a catalyst diluter that includes catalysts for diluting hydrogen in the exhaust gas by generating a catalytic reaction, the catalyst diluter being connected to the exhaust line; and an air diluter that is disposed outside the catalyst diluter and guides external air to a gas exit side of the catalyst diluter, in which the catalyst diluter may include a valve unit that opens and closes an external air channel of the air diluter in accordance with flow pressure of the exhaust gas.

A method for stopping a fuel cell system includes supplying a fuel gas containing a fuel to an anode of a fuel cell which is to generate electric power. An oxidant gas containing an oxidant is supplied to a cathode of the fuel cell. A concentration of the oxidant gas in the cathode is reduced. An output voltage of the fuel cell is lowered while a slope of a change in the output voltage with respect to elapsed time is controlled such that an output current of the fuel cell has a predetermined relationship with a predetermined current reference value.

When a temperature measured by a temperature measurer is below a specified temperature, a controller of a fuel cell system activates a fuel-gas-concentration increasing mechanism by using electric power of a secondary battery, and executes a fuel-gas-concentration increasing process for increasing the fuel gas concentration toward a first target concentration. When the fuel gas concentration reaches equal to or more than a second target concentration lower than the first target concentration, the controller starts power generation by a fuel cell to activate the fuel-gas-concentration increasing mechanism by using electric power from the fuel cell, and executes the fuel-gas-concentration increasing process until the fuel gas concentration reaches the first target concentration or more.

A redox flow battery with an electrochemical balancing cell having first and second chambers. The first chamber includes a catalyst coated substrate and the second chamber includes an electrode. Each receives an electrolyte from the redox flow battery. There is a single interface between the two chambers. The balancing cell reverses parasitic reactions in the first chamber that occur in the redox flow battery. The products of the reversed reactions are carried away from the electrochemical balancing cell and back to the redox flow battery in the electrolyte that carried the reactant to the first chamber. Also, processes for reversing a parasitic reaction in a redox flow battery.