Abstract: It is proposed to arrange a plurality of individual separator elements (48, 49) on the first side (40) of the membrane (38) in order to provide a humidifier (37) with integrated water separator, in particular for fuel cells (11) having a water vapor permeable membrane (38) and separator elements (48, 49) for separating water, wherein the membrane (38) on a first side (40) is in contact with a first channel (41) for a first humid gas stream, and on the second side (42) is in contact with a second channel (43) for a second, dry gas stream to be humidified, which allows an optimized exchange of moisture between the exhaust gas and operating medium streams of a fuel cell. Also provided is a fuel cell system and vehicle having the aforementioned humidifier.

Abstract: A multi-stack fuel cell system includes upper and lower housings defining interior chambers in corresponding upper and lower stacks of fuel cells are disposed. A heat exchanger assembly is fluidly coupled with the interior chambers. The heat exchanger assembly receives input fuel and/or input air from outside of the housings and receives outgoing fuel and/or outgoing air from the fuel cells. The heat exchanger assembly heats the input fuel and/or the input air, and/or cools the outgoing fuel and/or the outgoing air. The heat exchanger assembly may be disposed between the upper and lower housings. The upper housing an upper stack of fuel cells and/or the heat exchanger assembly may assist in compressing the fuel cells in the lower stack against each other.

Abstract: A cooling and humidifying device includes: a cooling portion cooling cathode gas by exchanging heat between the cathode gas and coolant; a humidifying portion including a moisture permeable member and humidifying the cathode gas by use of moisture contained in cathode off-gas; and a case housing the cooling portion and the humidifying portion.

Abstract: An electrochemical cell has first and second flow fields on opposite sides of a membrane. The first flow field has a set of generally linear channels in which the flow of a fluid in the field is contained between parallel elongate ridges. The second flow field is defined by a set of parallel discontinuous ridges. Preferably most ridge segments in the second flow field are oblique, for example perpendicular, to and overlap with two or more ridges of the first flow field. The flow fields may be used in, for example, water electrolysis cells including high or differential pressure polymer electrolyte membrane (PEM) electrolysis cells.

Abstract: A multilayer structure comprises a plurality of composite structures in a stacked configuration, each having a copper layer having a thickness of no larger than 25 ?m, and first and second graphene layers sandwiching the copper layer. The first graphene layer of a first composite structure among the plurality of composite structures directly contacts a second graphene layer of a second composite structure among the plurality of composite structures to form a graphene bi-layer structure. Either the first or second graphene layer of the graphene bi-layer structure comprises silver atoms, but not both. The silver atoms are ring-centered on graphene rings and delocalized inside the graphene rings.

Abstract: A system for controlling the temperature of a rechargeable electric battery pack for a vehicle includes a plurality of rechargeable electrochemical storage cells disposed in rows of one or more cells each. The system includes two heat exchanger plates for each of the rows of one or more cells. Each heat exchanger plate is configured to allow heat transfer fluid to flow internally thereof and a first of two heat exchanger plates for one of the rows is configured to allow heat transfer fluid to flow in a first general direction. A second of the two heat exchanger plates for the row is configured to allow heat transfer fluid to flow in a second general direction. The first and second general directions are substantially different to one another.

Abstract: A water level measuring system includes a distance sensor, a disturbance detecting unit, and a computation unit. The distance sensor is provided above a road and configured to output a sensor signal that includes a signal component representing a distance to a road surface of the road or a distance to an object present on the road surface. The disturbance detecting unit is configured to detect, from the sensor signal, a disturbance part acquired in a period in which a moving body is passing below the distance sensor. The computation unit is configured to compute a water level of water flooding the road based on the sensor signal from which the disturbance part has been eliminated.

Abstract: A separator for a fuel cell includes: a metal base material; and a carbon coating layer formed on one surface or both surfaces of the metal base material, in which roughness Ra formed at an interface between the metal base material and the carbon coating layer may be in a range of 20 to 78 nm.

Abstract: The invention relates to a fuel cell system having lines for feeding hydrogen from a high-pressure hydrogen reservoir into a fuel cell assembly. The lines have a high-pressure region, a medium-pressure region, and a fuel cell operating-pressure region. The lines of the medium-pressure region are pressure-relieved upon deactivation of the fuel cell system in order to avoid hydrogen diffusing out during standstill periods of the fuel cell system, and to thus avoid the formation of explosive hydrogen/air mixtures. The invention also relates to a tank module, which is configured for pressure relieving, to a method of deactivating and re-activating the fuel cell system, to the use of a 3/2-way valve for pressure-relieving the medium-pressure region of the hydrogen lines of a fuel cell system, and to a motor vehicle having a fuel cell system or tank module.

Abstract: The present invention relates to a method and an apparatus of preparing a reduction product of carbon dioxide by electrochemically reducing carbon dioxide.

Abstract: Apparatuses and methods of measuring a hydrogen diffusivity of a metal structure including during operation of the metal structure, are provided. A hydrogen charging surface is provided at a first location on an external surface of the structure. In addition, a hydrogen oxidation surface is provided at a second location adjacent to the first location on the external surface of the structure. Hydrogen flux is generated and directed into the metal surface at the charging surface. At least a portion of the hydrogen flux generated by the charging surface is diverted back toward the surface. A transient of the diverted hydrogen fluxes measured, and this measurement is used to determine the hydrogen diffusivity of the metal structure in service.

Abstract: A fuel cell system according to one embodiment performs refresh control of an electrode catalyst of a fuel cell, by reducing a stack voltage as a voltage of the fuel cell to a refresh voltage at which the electrode catalyst is activated. The system includes the fuel cell that generates electric power by an electrochemical reaction using fuel gas and oxidation gas, a stack voltage sensor that sensors the stack voltage, and a controller that controls power of the fuel cell. When a high load demand that makes the stack voltage lower than a given voltage is made on the fuel cell, the controller causes the fuel cell to deliver power commensurate with the high load demand, and performs refresh control when the stack voltage becomes lower than the given voltage through the above control.

Abstract: An electrochemical cell system and a method for operating an electrochemical cell is provided. The method including determining one of a power level, current level or a voltage level of the electrochemical cell, the electrochemical cell including at least one cell having an anode side and a cathode side, the electrochemical cell further having a water transport plate operably coupled to the cathode side. An oxidant pressure level is determined in the cathode side. A water pressure level is determined in the water transport plate. The active area of the at least one cell is changed by adjusting at least one of the oxidant pressure level or the water pressure level based at least in part on the determined power level, current level or voltage level.

Abstract: Apparatuses and methods of measuring a hydrogen diffusivity of a metal structure including during operation of the metal structure, are provided. A hydrogen charging surface is provided at a first location on an external surface of the structure. In addition, a hydrogen oxidation surface is provided at a second location adjacent to the first location on the external surface of the structure. Hydrogen flux is generated and directed into the metal surface at the charging surface. At least a portion of the hydrogen flux generated by the charging surface is diverted back toward the surface. A transient of the diverted hydrogen fluxes measured, and this measurement is used to determine the hydrogen diffusivity of the metal structure in service.

Abstract: A fuel cell system includes: a low-frequency superimposition section superimposing a the low-frequency signal on a fuel cell; and an impedance computation section configured to compute low-frequency impedance of the fuel cell at a time when the low-frequency superimposition section superimposes the low-frequency signal on the fuel cell. The fuel cell system includes: a diagnosing section diagnosing a degree of dryness inside the fuel cell on the basis of low-frequency impedance; and an oxidant gas amount adjustment section configured to adjust an amount of oxidant gas in the fuel cell. The diagnosing section is configured to diagnose the degree of dryness inside the fuel cell on the basis of the low-frequency impedance when the oxidant gas amount adjustment section adjusts the amount of the oxidant gas to be equal to or smaller than a reference gas amount.

Abstract: A system for heating or cooling a fuel cell circuit includes a fuel cell stack designed to receive a fluid. The system also includes a temperature sensor to detect a fluid temperature of the fluid, an actuator to increase or decrease the fluid temperature, and an electronic control unit (ECU). The ECU is designed to receive a target fuel cell temperature corresponding to the fuel cell stack and based on a power request, to determine a temperature rate of change corresponding to a desired rate of temperature change of a current fuel cell temperature of the fuel cell stack to achieve the target fuel cell temperature based on the target fuel cell temperature, and to control the actuator to increase or decrease the fluid temperature based on the temperature rate of change to cause the current fuel cell temperature to increase or decrease to the target fuel cell temperature.

Abstract: A method for flushing a fuel cell system during a power-down cycle includes conveying air by an air conveying device through a cathode space of a fuel cell and releasing the conveyed air through an exhaust air line. An outlet valve is cyclically closed and opened during the power-down cycle, where an opening duration depends on an amount of air that is conveyed and the outlet valve connects an anode discharge line to the exhaust air line. The conveyed air is guided from a delivery side of the air conveying device directly to the exhaust air line at least in part through a system bypass.

Abstract: A fuel cell system includes: a fuel cell stack; a fuel gas supply/exhaust unit; an oxidant gas supply/exhaust unit; and a control unit. The control unit determines whether there is a phenomenon in the fuel cell stack resulting from local power generation concentration within a plane of a membrane electrode assembly due to a water distribution. When it is determined that there is the phenomenon, the control unit controls at least one of the fuel gas supply/exhaust unit and the oxidant gas supply/exhaust unit.

Abstract: A fuel cell vehicle includes a fuel cell module accommodated in a fuel cell accommodation space disposed in a front portion of the vehicle, a hydrogen circulation flow path configured to recirculate anode off-gas that is discharged from a fuel cell constituting the fuel cell module to the fuel cell, and a hydrogen pump provided in the hydrogen circulation flow path and fixed to a lower portion of the fuel cell module. The hydrogen pump is fixed to the fuel cell module via a bracket and the deformation strength of the bracket is set to be lower than a load input from a wall portion behind the fuel cell accommodation space at the time of collision of the vehicle.

Abstract: A bipolar plate is provided that comprises a flow field. The bipolar plate is part of a fuel cell and may comprise a chamber, such as a reactants accumulation chamber, on a first side of the bipolar plate. The flow field may comprise a plurality of holes, such as a jet array of impingement jet passages. The flow field may comprise a plurality of channels on a second side of the bipolar plate. The plurality of holes may be configured to conduct reactants from the first side of the bipolar plate to the second side of the bipolar plate to impinge on a membrane electrode assembly (MEA) of the fuel cell. The plurality of channels on the second side of the bipolar plate are configured to conduct a portion of the reactants and/or reaction products to an output hole and/or a channel.

Abstract: In one embodiment, a gas diffusion layer for fuel cells includes a fine porous layer formed on a carbon fiber support and being interposed between a membrane-electrode assembly (MEA) and a separator. The carbon fiber support includes a fine pore area having a predetermined average pore size in a separator direction (thickness direction) in the membrane electrode assembly, and a coarse pore area having a larger predetermined average pore size than the average pore size of the fine pore area in the separator direction (thickness direction) in the membrane electrode assembly. The fine pore area and the coarse pore area are alternately formed.

Abstract: What is disclosed here is an alternative energy booster apparatus that increases the performance and electricity generation that can be added to alternative energy systems, that includes enhanced energy generation utilizing layered materials, thermal materials, infrared, multiple power cells generation, light transferal of energy, and manufacturing to enhance electricity generation, storage, security, with embedded EMP protection of the apparatus that increases reliability, restorability and sustainability of the apparatus. The apparatus additionally utilizes mechanical, chemical, and computer controlled switching components to increase the electric voltage and current being generated, stored, and distributed managed by a computer controller.

Abstract: A fuel cell vehicle includes tanks configured to store a fuel gas to be supplied to the fuel cell, the tanks being respectively disposed in front of and behind the motor drive unit such that a longitudinal direction of each of the tanks corresponds to a width direction of the fuel cell vehicle. The tanks are disposed such that respective end portions of the tanks on a side on which the high-voltage wiring portion is positioned are outside the high-voltage wiring portion in the width direction of the fuel cell vehicle and the respective end portions of tanks overlap a tire-wheel assembly in a front-rear direction of the fuel cell vehicle.

Abstract: Disclosed are a fuel cell system and a method for controlling the same which enable performance recovery of a stack together with a high potential avoidance operation while operating the fuel cell system. The fuel cell system includes a fuel cell stack, in which a first separation plate having a first air flow path and a second separation plate having a second, different air flow path are alternately stacked with a membrane-electrode assembly interposed therebetween; and the method includes determining whether a high-potential avoidance operation is required while operating the fuel cell system including the fuel cell stack, and selectively supplying air to the air flow path of the first separation plate or the second separation plate when a high-potential avoidance operation is required, so as to easily achieve cathode performance recovery during the high-potential avoidance operation of the fuel cell system and the operation of the fuel cell system.

Abstract: The present embodiments provide: a reduction catalyst having high reaction efficiency, a reduction reactor including the same and a reduction method using the same. This catalyst includes a conductor and an organic layer comprises organic modifying groups capable of binding to the surface of the conductor, wherein the organic modifying groups contain a nitrogen-containing heterocycle.

Abstract: A fuel cell system that includes a component for removing anionic contaminants is provided. The fuel system including a fuel cell stack, a fuel gas feed subsystem in communication with fuel cell anodes in the fuel cell stack, an oxygen-containing gas feed subsystem system in communication with fuel cell cathodes in the fuel cell stack, and an anionic scavenging subsystem in communication with the fuel gas feed subsystem and/or the an oxygen-containing gas feed subsystem.

Abstract: A parts arrangement structure of a fuel cell electric vehicle (FCEV) is provided. The structure improves ease of assembly and maintenance of parts, by efficiently arranging and modularizing a fuel cell system, a drive device, and some of electric parts, which are installed within the FCEV.

Abstract: An apparatus and a method for controlling a fuel cell stack are provided to improve the performance (output) of the fuel cell stack that has suffered from deterioration. The performance is improved by adjusting a stoichiometric ratio (SR) of air supplied to the fuel cell stack and an operating temperature of the fuel cell stack based on the basis of an open-circuit decay time (ODT) indicating a time taken for a cell voltage to be reduced from a reference voltage to a threshold voltage when the supply of air to the fuel cell stack is cut off.

Abstract: A manifold device of a fuel cell stack is provided which prevents moisture condensed in gases supplied to the fuel cell stack from excessively flowing into specific cells of the stack by heating gases supplied into the stack using heat of the stack. The manifold device also prevents flooding that is caused by liquid generated in cells disposed away from a gas inlet by removing a flow rate difference of gases generated in respective cells based on distances from the gas inlet of the stack.

Abstract: An ionic conductivity measurement device of an electrolytic membrane includes a humidification chamber configured to accommodate an ion-conductive electrolytic membrane and having concave grooves respectively formed at both sides thereof which face the electrolytic membrane to form a measurement space for measuring ionic conductivity of the electrolytic membrane; a plurality of channels formed at a bottom surface of each of the concave grooves; a gas distribution unit detachably coupled to each of the concave grooves with the electrolytic membrane being interposed therebetween; and a plurality of electrodes provided in contact with one side of the electrolytic membrane and supported by the gas distribution unit, the plurality of electrodes being disposed side by side to measure an impedance of the electrolytic membrane.

Abstract: An air supply device using a cooling water heater of a fuel cell vehicle can effectively reduce cold starting time of the fuel cell vehicle and effectively remove moisture in a stack in cold shut down (CSD) of the fuel cell vehicle. In the air supply device, a bypass flow path is formed to be branched from a first air supply line connected between an air blower for supplying air to a fuel cell stack and a humidifier for humidifying the air supplied to the stack. The bypass flow path allows air exhausted from the air blower to pass through a cooling water heater by bypassing the humidifier and then to be supplied to the stack.

Abstract: A method of shutting down a fuel cell system includes a fuel cell includes generating power via an electrochemical reaction between a fuel gas and an oxidant gas. A shutdown command is output to the fuel cell to stop generating power. The fuel cell is controlled to continue generating power during an oxygen consumption process to consume oxygen in the oxidant gas remaining in a cathode system of the fuel cell even when the shutdown command is output to the fuel cell. At least one of voltage, current, and power output from the fuel cell is detected during the oxygen consumption process. Whether an abnormality occurs during the oxygen consumption process is determined based on at least one of the voltage, the current, and the power. The fuel cell is controlled to stop generating power during the oxygen consumption process when it is determined that abnormality occurs.

Abstract: The present invention relates to an organic flow cell battery having a material comprising an organic molecule that can be used as the electroactive redox material for both electrodes of the battery. By enabling two-electron processes both of the oxidation and reduction to occur in a single molecule, a total of 4-electron transitions is achieved, which allows the organic molecule to be used on both sides of the separator, reducing material costs and allowing the battery to be charge in either direction with equal ease.

Abstract: A fuel gas supply path in a fuel cell stack includes in series a first path, a second path, and a third path. In the second path, two inlets of the fuel gas in each of power generating cells included in the second path are located at a first position PA and a second position PB, and the position of one outlet of the fuel gas in each power generating cell is located at a third position PC. In the third path, an inlet of the fuel gas in each of power generating cells included in the third path is located at a position coinciding with the third position PC when the power generating cells are viewed in the stacking direction, and an outlet of the fuel gas in each power generating cell is located at a position between the first position PA and the second position PB.

Abstract: Disclosed are a reinforced composite membrane for fuel cells including a porous support comprising three-dimensionally irregularly and discontinuously arranged nanofibers of a polymer and a first ionic conductor, and a second ionic conductor filling pores of the porous support, wherein the first ionic conductor is present as nanofibers in the porous support or is present in the nanofibers of the polymer to form the nanofibers together with the polymer, and a membrane-electrode assembly for fuel cells including the same. As a result, impregnation uniformity and impregnation rate of the ionic conductors are improved and proton (hydrogen ion) conductivity is thus enhanced.

Abstract: An exemplary fuel cell component includes a plate having a plurality of channels. At least a first one of the channels is configured differently than others of the channels so that the first channel provides a first cooling capacity to a selected portion of the plate. The others of the channels provide a second, lesser cooling capacity to at least one other portion of the plate.

Abstract: A power generator includes a case having a surface with a perforation and a cavity containing a gas generating fuel. A membrane is supported by the case inside the cavity, the membrane having an impermeable valve plate positioned proximate the perforation, wherein the membrane is water vapor permeable and gas impermeable and flexes responsive to a difference in pressure between the cavity and outside the cavity to selectively allow water vapor to pass through the perforation to the fuel as a function of the difference in pressure. A fuel cell membrane is supported by the case and positioned to receive hydrogen at an anode side of the fuel cell membrane and to receive oxygen from outside the power generator at a cathode side of the fuel cell membrane.

Abstract: A fuel cell system includes: a fuel cell supplied with fuel gas for power generation; a fuel supply flow passage flowing fuel gas, supplied from a fuel supply source, to the fuel cell; a pressure regulating valve regulating a pressure of fuel gas flowing through the fuel supply flow passage; a fuel circulation flow passage returning gas, emitted from the fuel cell, to the fuel supply flow passage; a circulation pump delivering gas in the fuel circulation flow passage to the fuel supply flow passage; an emission valve emitting gas in the fuel circulation flow passage to an outside; and a control device controlling the pressure regulating valve, the circulation pump and the emission valve such that the sum of losses of crossover hydrogen, circulation pump power and purge hydrogen is minimum while a hydrogen stoichiometric ratio required for power generation of the fuel cell is ensured.

Abstract: The present specification relates to a polymer with improved acid resistance, a polymer electrolyte membrane including the same, a membrane-electrode assembly including the polymer electrolyte membrane, a fuel cell including the membrane-electrode assembly, and a redox flow battery including the polymer electrolyte membrane.

Abstract: An electrochemical reaction unit containing a single cell including an electrolyte layer containing solid oxide, and a cathode and an anode which face each other in a first direction with the electrolyte layer intervening therebetween; a current collector disposed on a cathode side of the single cell and having a protrusion protruding toward the cathode; an electrically conductive coat covering a surface of the current collector; and an electrically conductive bonding layer bonding the cathode and the protrusion covered with the coat. In at least one section of the protrusion taken in parallel with the first direction, the protrusion covered with the coat has a covered portion covered with the bonding layer and an exposed portion exposed from the bonding layer and including a corner portion of the protrusion covered with the coat.

Abstract: A fluid handling device that is adapted to heat or cool a first fluid flow, the device includes a thermal chamber adapted to heat or cool the first fluid flow in the thermal chamber; and an input channel which is adapted to channel the first fluid flow into the thermal chamber, an outlet channel which is adapted to channel a heated or cooled second fluid flow out of the thermal chamber, such that the thermal energy of the second fluid flow along the outlet channel is higher or lower than the thermal energy of the first fluid flow along the input channel. The outlet channel is thermally connected to the input channel, so that the outlet channel is adapted to transfer thermal energy between the heated or cooled second fluid flow along the outlet channel and the first fluid flow along the input channel to heat or cool the first fluid flow before entering the thermal chamber.

Abstract: A system for managing water content in one or more electrochemical cells, each comprising a plurality of electrodes and a liquid ionically conductive medium, includes a first gas-phase conduit for receiving humid gas-phase associated with the electrochemical cell. The system also includes a desiccator unit communicated to the first air conduit and configured for extracting water from the humid gas-phase. The system additionally includes a heater for selectively heating the desiccant to selectively release extracted water from the desiccator unit. The system further includes a return conduit communicating the desiccator unit to the ionically conductive medium for receiving extracted water from the desiccator unit, and directing the extracted water to the ionically conductive medium. Other associated systems and methods are also disclosed.

Abstract: A fuel-cell stack system includes a stack of electrochemical cells, a fuel gas supply circuit and an oxidant gas supply circuit, a cooling circuit, a micropump, a temperature measurement device, and a controller. The cells are separated by bipolar plates, with each bipolar plate including an anode, a cathode, and an ion-exchange membrane. The cooling circuit, which is structured to enable a coolant fluid to circulate therein, includes a secondary circuit and a primary circuit that is smaller in size than the secondary circuit, with the primary and secondary circuits being isolated from each other by a thermostatic valve. The micropump is installed at an outlet of the stack and enables a volume of water inside the stack to be mixed. The temperature measurement device determines an internal temperature of a core of the stack. The primary circuit is activated when the internal temperature rises above a predetermined threshold.

Abstract: A high-temperature polymer electrolyte membrane fuel cell stack may include a plurality of cell units; a cooling assembly including a plurality of first independent cooling plates disposed on top surfaces of the plurality of cell units, respectively, and a plurality of second independent cooling plates disposed on bottom surfaces of the plurality of cell units, respectively; and a support assembly configured to support the plurality of cell units and the cooling assembly.

Abstract: A method for controlling a fuel cell system including a fuel cell, includes measuring an impedance of the fuel cell that includes a solid polymer electrolyte membrane to generate electric power via an electrochemical reaction between a fuel gas and an oxidant gas. An output electric current output from the fuel cell is increased to a threshold electric current value when the impedance is equal to or higher than a threshold impedance value and a target electric current value is larger than the threshold electric current value. The output electric current is maintained at the threshold electric current value. The output electric current is increased from the threshold electric current value to the target electric current value.

Abstract: According to one embodiment of this disclosure an integrated fuel cell and environmental control system includes a turbo-compressor. The turbo-compressor includes a rotatable shaft, a compressor rotatable with the shaft to generate a flow of compressed air, a motor connected to the shaft, and a turbine connected to the shaft. The system further includes a fuel cell connected to the compressor by a first compressed air supply line that supplies a first portion of the flow of compressed air to the fuel cell. The fuel cell is connected to the turbine by a fuel cell exhaust line that supplies a flow of fuel cell exhaust to the turbine and causes the turbine to rotate. The system further includes an environmental control system connected to the compressor by a second compressed air supply line that supplies a second portion of the flow of compressed air to the environmental control system.

Abstract: A method of determining hydrogen deficiency of a fuel cell having a plurality of cell groups includes a reference value storage step of storing, as a reference value, a value of impedance in a state where hydrogen-off gas is discharged from the fuel cell and hydrogen gas and oxidant gas are supplied, a measured value calculation step of calculating a measured value of impedance based on a voltage of the cell groups and a current of the fuel cell, a corrected value calculation step of calculating a corrected value of impedance by correcting the measured value based on the reference value, and a determination step of determining that hydrogen deficiency occurs in a case where the corrected value exceeds a predetermined threshold.

Abstract: A method for controlling a fuel cell system includes supplying an oxidant gas, via an oxidant gas supply channel, to a cathode electrode of a fuel cell. The oxidant gas is moistened to be supplied to the cathode electrode with a humidifier. An opening degree of a bypass channel valve is decreased via a feedforward control to a first opening degree when an impedance has reached a lower limit value. The opening degree of the bypass channel valve is increased via the feedforward control to a second opening degree when the impedance has reached an upper limit value. The first opening degree is smaller than the second opening degree.

Abstract: An electrochemical cell has first and second flow fields on opposite sides of a membrane. The first flow field has a set of generally linear channels in which the flow of a fluid in the field is contained between parallel elongate ridges. The second flow field is defined by a set of parallel discontinuous ridges. Preferably most ridge segments in the second flow field are oblique, for example perpendicular, to and overlap with two or more ridges of the first flow field. The flow fields may be used in, for example, water electrolysis cells including high or differential pressure polymer electrolyte membrane (PEM) electrolysis cells.

Abstract: A method for controlling a pressure drop across the anode side or the cathode side of a fuel cell stack by controlling the intrusion of a cell separator into the flow channels in a feeder region of the stack so as to create a larger pressure volume on a pressure bias side of the stack. The method controls the flow rates of one or both of the cathode and anode reactant gases so as to cause the cell separators in an inlet feeder region and/or an outlet feeder region to move relative to the anode side and the cathode side so as to change a flow volume in the inlet feeder region and/or the outlet feeder region to control the pressure drop.