A fuel cell system includes a fuel cell that generates power through electrochemical reaction between fuel gas and oxidant gas, a fuel gas supply path for supplying the fuel gas to an anode of the fuel cell, an offgas discharge path for discharging offgas from the anode of the fuel cell, a recycle gas path bifurcated from the offgas discharge path at a bifurcation and then joining the fuel gas supply path, a flow rate adjuster that is provided on the recycle gas path and adjusts a flow rate of gas flowing through the recycle gas path, a purge valve provided on the offgas discharge path downstream of the bifurcation, and a controller that controls the flow rate adjuster so that an internal pressure of the offgas discharge path upstream of the purge valve is positive.

A fuel cell system includes a fuel cell that generates electric power using fuel gas and oxidant gas, a fuel gas supply path through which the fuel gas is supplied to an anode inlet of the fuel cell, a recycle gas path through which anode off-gas discharged from an anode outlet of the fuel cell returns to the fuel gas supply path, and a pressure booster arranged in the recycle gas path, and the pressure booster is arranged above a confluence portion where the fuel gas supply path and the recycle gas path meet each other when gravity acts downward from above.

A bipolar plate structure having optimized gas flow channels is disclosed herein. It mainly comprises an anode electrode plate having a gas flow path plane molded by stamping processing and a plurality of zigzag meandering zigzag meandering grooves formed on the gas flow path plane for a flow of hydrogen; and a cathode electrode plate having a gas flow path plane molded by stamping processing and a plurality of zigzag meandering zigzag meandering grooves formed on the gas flow path plane for a flow of oxygen.

The present disclosure is directed to a method for tuning the performance of at least one electrochemical cell of an electrochemical cell stack. The method includes supplying power to an electrochemical cell stack. The electrochemical cell stack includes a plurality of electrochemical cells. The method further includes monitoring a parameter of at least one electrochemical cell and determining if an electrochemical cell becomes impaired. The method also includes diverting a fraction of the current flow from the impaired electrochemical cell during operation of the electrochemical cell stack.

The present disclosure is directed to a method for tuning the performance of at least one electrochemical cell of an electrochemical cell stack. The method includes supplying power to an electrochemical cell stack. The electrochemical cell stack includes a plurality of electrochemical cells. The method further includes monitoring a parameter of at least one electrochemical cell and determining if an electrochemical cell becomes impaired. The method also includes diverting a fraction of the current flow from the impaired electrochemical cell during operation of the electrochemical cell stack.

A method of cleaning power cells in an array of power cells, comprising coupling at least one first power cell to second power cells in an array of power cells and causing the second power cells to drive the at least one first power cell with a voltage to clean catalyst on the at least one first power cell.

The present disclosure is directed to a method for tuning the performance of at least one electrochemical cell of an electrochemical cell stack. The method includes supplying power to an electrochemical cell stack. The electrochemical cell stack includes a plurality of electrochemical cells. The method further includes monitoring a parameter of at least one electrochemical cell and determining if an electrochemical cell becomes impaired. The method also includes diverting a fraction of the current flow from the impaired electrochemical cell during operation of the electrochemical cell stack.

Disclosed is an apparatus for controlling a fuel concentration of a liquid fuel cell apparatus by voltage amplitude control-based feed-back control without using a concentration sensor, which saves power consumed by the fuel cell apparatus and lowers a price of the fuel cell apparatus by using the fuel cell in a simple and small design without using a concentration sensor.

A fuel cell internal state detection system includes estimation object state quantity setting unit for setting a suitable estimation object state quantity as an index of an internal state, an impedance value acquisition unit configured to obtain an impedance value of a fuel cell, an impedance usability judging unit configured to judge whether or not the obtained impedance value is usable for the calculation of the estimation object state quantity, estimation object state quantity calculation unit for calculating the estimation object state quantity set by the estimation object state quantity setting unit on the basis of the obtained impedance value when the impedance value is judged to be usable for the calculation of the estimation object state quantity by the impedance usability judging unit, and an unusable-scene process execution unit configured to perform an unusable-scene process when the impedance value is judged not to be usable for the calculation of the estimation object state quantity by the impedance usability judging unit.

The present invention relates to a determination method (200) for determining a crossover rate (CR) of at least one fuel cell (10) of a fuel cell system (100) for regulation of the fuel cell system (100), the determination method (200) having the following method steps: detecting (202) fill levels (F) of water (W) in a moisture separator (20) of the fuel cell system (100) by means of a fill level detection device (24), draining (204) water (W) out of the moisture separator (20) using a drainage device (22) of the moisture separator (20), measuring (206) a first time (t1) during drainage (204) between a first fill level (F1) and at least a second fill level (F2) of the water (W) in the moisture separator (20), determining (208) the crossover rate (CR) of the at least one fuel cell (10) from the measured first time (t1) and the at least two measured fill levels (F1, F2) by means of a computer unit (30) of the fuel cell system (100), wherein the crossover rate (CR) corresponds to a transition rate of water (W) from a cathode side (K) of the at least one fuel cell (10) to the anode side (A) of the at least one fuel cell (10).

The invention also relates to a fuel cell system (100) having a plurality of fuel cells (10), a moisture separator (20), a drainage device (22), a fill level detection device (24), and a computer unit (30).