A fuel cell system includes a supply channel having first channels respectively connected with tanks, and a second channel merged with each of the first channels; first on-off valves of the first channels; a second on-off valve of the second channel; and a controller configured to control opening and closing of the first on-off valves and the second on-off valve. In a state where the second on-off valve is closed, the controller supplies first electric power used for opening the first on-off valve against a first differential pressure to at least one first on-off valve, and supplies second electric power, smaller than the first electric power and used for opening the first on-off valves against a second differential pressure smaller than the first differential pressure, to the first on-off valves other than the at least one first on-off valve.

A method of operating a redox flow battery, may include maintaining a positive electrode compartment pressure greater than a negative electrode compartment pressure, and maintaining a cross-over pressure less than a membrane break-through pressure, wherein the cross-over pressure equals the negative electrode compartment pressure subtracted from the positive electrode compartment pressure. In this way, ionic resistance across the separator can be maintained at a lower level by reducing gas bubbles trapped therein while reducing separator break-through, thereby increasing performance of the redox flow battery system.

A fuel cell system includes a plurality of fuel cell stacks or columns, each fuel cell stack or column containing a plurality of fuel cells, and at least one pressure drop tool located in a fuel path of at least one first fuel cell stack or column but not in a fuel path of at least one second fuel cell stack or column.

A redox flow battery according to the present invention is provided with a battery module including a battery cell or a stack, and a pair of electrolyte tanks, and a replacement of a pump is applied for each battery module to transfer electrolyte to the battery cell and the stack such that shunt current is reduced. In addition, each battery module is provided with the pair of the electrolyte tanks such that a transfer distance of the electrolyte can be reduced, and a fluid controller using pressure instead of a pump for each module such that power required for driving the pump can be reduced and efficiency of the battery can be improved.

A pressure control system of a fuel cell stack includes: an air supply control unit for controlling a revolutions per minute (RPM) of an air compressor for supplying air to a cathode side of the fuel cell stack based on a required output of the fuel cell stack; a hydrogen supply control unit for controlling a pressure at an anode side of the fuel cell stack with a target pressure based on the required output of the fuel cell stack; and a differential pressure control unit for controlling the air supply control unit or the hydrogen supply control unit to calculate a differential pressure between the anode side and the cathode side of the fuel cell stack, and to modify the target pressure or the RPM of the air compressor based on the calculated differential pressure.

Recirculation arrangements and methods are disclosed for high temperature fuel cell systems or electrolysis cell systems. Exemplary embodiments recirculate gas exhausted from at least one of an anode side and a cathode side. A desired recirculated flow rate is provided by an ejector supplied with at least one primary feedstock fluid and a supplementary fluid to a nozzle with a convergent-divergent flow channel. A respective ratio of the primary and supplementary fluids of the ejector maintains a desired motive flow and pressure at the nozzle to accomplish desired recirculated flow rate. The supplementary fluid is cutoff when a level of system loading is such that the primary feedstock fluid alone maintains the desired motive flow and pressure at an ejector inlet.

A method of operating a fuel cell stack is described. The fuel cell stack includes a cathode, an anode, and a temporarily disabled bleed valve that is otherwise configured to transition from a first position to a second position and thereby modulate nitrogen drained from the anode. The method includes increasing a first pressure in the anode via a controller and, concurrent to increasing, decreasing a second pressure in the cathode via the controller. A system and a device including the fuel cell stack are also described.

A fuel cell system used in a vehicle equipped with a fuel cell includes: a fuel cell; a fuel gas supply portion which supplies a fuel gas to the fuel cell; a fuel gas discharge portion which discharges exhaust fuel gas from the fuel cell; and a control unit, in which, when an operation of the fuel cell is ended, the control unit performs (a) an exhaust process of discharging the exhaust fuel gas of the fuel cell to reduce a pressure, and (b) a process of increasing a partial pressure of the fuel gas in the fuel cell by supplying the fuel gas to the fuel cell after the exhaust process.

In a fuel cell system intended for a pressure-independent operation, in which at least one fuel cell having an open cathode is provided, a first fluid chamber adjoins an inflow cross section and a second fluid chamber adjoins an outflow cross section. In the fluid chambers can be set an overpressure which is adapted to the operation of the at least one fuel cell.

A resin film equipped MEA of a power generation cell includes a membrane electrode assembly and a resin film. An inner peripheral end of a first frame shaped sheet of the resin film is positioned outside an outer peripheral end of a cathode, and faces the outer peripheral end of the cathode so as to be separated by a gap. An inner peripheral portion of a second frame shaped sheet is held between the anode and the cathode. A first metal separator facing the first frame shaped sheet is provided with protruding support structure configured to support an inner peripheral portion of the first frame shaped sheet and an outer peripheral portion of the cathode.