Abstract: A solid oxide fuel cell stack is provided in which a separate fuel-blocking unit is provided to each fuel supply tube that connects a fuel supply unit to each bundle portion of the stack, so that the fuel supply to a defective bundle portion may be selectively blocked, thereby preventing the risk of explosion due to fuel leakage and the performance degradation of the other bundle portions. To this end, a fuel cell stack includes a bundle portion including unit cells each having a stacked structure of a first electrode, an electrolytic layer, and a second electrode, and a manifold having the unit cells connected thereto. A fuel supply portion is connected to the manifold of the bundle portion through a fuel supply tube provided at one side thereof. A fuel-blocking unit is connected to the fuel supply tube to block the fuel supply tube.

Abstract: A fuel cell and an electronic apparatus with same mounted thereon are provided. The fuel cell includes a power generation unit provided with a conduit for an oxidant gas containing at least oxygen, a heat radiation unit connected to the power generation unit so as to radiate heat from the power generation unit, a gas flow means for causing the oxidant gas to flow in the conduit, and a cooling means driven independently from the gas flow means so as to cool the heat radiation unit. By independently controlling the driving of the gas flow means and the cooling means, the fuel cell can be driven in such a manner that the temperature of the power generation unit and the amount of water remaining in the power generation unit are regulated into preferable conditions. Furthermore, it is possible to provide a fuel cell and an electronic apparatus with the same mounted thereon in which power generation can be performed stably and various apparatuses are contained therein in a compact form.

Abstract: A solid oxide fuel cell capable of maintaining performance over a long time period by appropriately changing fuel cell module operating conditions. The present invention is a solid oxide fuel cell (1), having a fuel cell module (2), a fuel supply device (38), an oxidant gas supply device (45), and a controller (110) for controlling the amount of fuel supplied from the fuel supply device; the controller is furnished with a degradation determining circuit (110a) for determining degradation in the fuel cell module and a degradation response circuit (110b) for changing fuel cell module operating conditions based on the degradation determination by the degradation determining circuit; the degradation determination stores fuel cell module operating results arising from the operating conditions changed by the degradation response circuit, and executes further degradation determination based on the stored operating results.

Abstract: A method for filling a fuel cell anode supply manifold with hydrogen prior to a start-up operation to facilitate a substantially even hydrogen distribution across the fuel cell is disclosed. The anode supply manifold is in fluid communication with a source of hydrogen. A first valve in fluid communication with the anode supply manifold and a second valve in fluid communication with an anode exhaust manifold are initially in a closed position while hydrogen is supplied to the anode inlet conduit to pressurize the fuel cell stack. The first valve is then opened to purge at least a portion of a fluid from the anode supply manifold to facilitate a filling of the manifold with hydrogen.

Abstract: A fuel cell system (10) includes: a fuel cell (1); a hydrogen supply device (2) for supplying a hydrogen gas to the fuel cell (1); an anode off-gas passage (22) through which an anode off-gas discharged from the anode side of the fuel cell (1) passes; a hydrogen concentration sensor (3) that measures the concentration of hydrogen in the anode off-gas; and a sensor correction device (4) that, after a predetermined time has elapsed since the hydrogen gas supply to the fuel cell by the hydrogen supply device (2) was stopped, measures the hydrogen concentration using the hydrogen concentration sensor (3), and corrects a measurement value from the hydrogen concentration sensor (3) based on the measured hydrogen concentration.

Abstract: Disclosed is a fuel cell system capable of stabilizing the power generation state of a fuel cell for a period of transition from a power generation stop state during an intermittent operation or the like to a usual operation. The fuel cell system supplies a fuel gas from a fuel supply source to a fuel cell to generate a power, and comprises output limit means for limiting the output of the fuel cell after shift from the power generation stop state of the fuel cell to a power generation state.

Abstract: A system and method for putting a fuel cell system in a stand-by during a system idle condition to improve system fuel efficiency. The method can include diverting the cathode airflow around the stack, reducing an airflow output from a cathode compressor to a minimum allowable set-point, opening the stack contactors to disconnect the stack from the high voltage bus and electrically isolate the stack from the rest of the system, engaging an independent load to the stack, such as end cell heaters in the stack, to suppress stack voltage, maintaining a positive pressure in the anode side of the fuel cell stack and periodically bleeding the anode into the exhaust stream. When a system power request is made removing the idle condition, the system returns to normal operation by directing the airflow back to the cathode and opening the stack contactors when an open circuit voltage is attained.

Abstract: A system and method for providing an anode exhaust gas bleed in a fuel cell system. The system provides a normal anode side bleed using first and second bleed valves if the first and second bleed valves are not blocked and the temperature of first and second split sub-stacks is greater than a predetermined temperature, provides a continuous anode side bleed using the bleed valves if the bleed valves are not blocked and the temperature of the sub-stacks is less than the predetermined temperature, provides a normal center anode bleed through the drain valve if the first or second bleed valve is blocked and the temperature of the sub-stacks is above the predetermined temperature and provides a continuous center anode side bleed through the drain valve if the first or second bleed valve is blocked and the temperature of the sub-stacks is below the predetermined temperature.

Abstract: In a fuel cell stack, an inlet fuel distributor (15, 31, 31a, 31b) comprises a plurality of fuel distributing passageways (17-23, 40-47, 64) of substantially equal length and equal flow cross section to uniformly distribute fuel cell inlet fuel from a fuel supply conduit (13, 14, 50) to a fuel inlet manifold (28). The conduits may be either channels (40-47; 64) formed within a plate (39) or tubes (17-23). The channels may have single exits (65) or double exits (52, 53) into the fuel inlet manifold.

Abstract: A fuel cell system comprising at least one fuel cell unit (1) to generate electrical power and at least one component, upstream and/or downstream of said fuel cell unit in the anode flow path, said component preventing, as a reoxidation barrier, reoxidation of parts of the anode sections or of the anode sections as a whole in the case that an oxidizing gas is entering.

Abstract: The fuel cell system is provided with a fuel cell, a fuel supply system for supplying fuel gas to the fuel cell, an injector for regulating the gas state upstream in the fuel supply system and supplying the gas downstream, and control means for driving and controlling the injector at a predetermined drive cycle. The control means sets the working state of the injector in response to the operating state of the fuel cell.

Abstract: In a fuel cell system, during the state where the fuel cell system is not generating an electric power, a fuel gas passage and an oxidizing gas passage are closed, and an inert gas supply device (54, 58) supplies an inert gas to an anode space (111) which is substantially isolated from outside, the anode space including the closed fuel gas passage and a space connected to the closed fuel gas passage, while an air supply device (67, 70) supplies air to a cathode space (112) which is substantially isolated from outside, the cathode space including the closed oxidizing gas passage and a space connected to the closed oxidizing gas passage. With this, the fuel cell system is capable of achieving high energy efficiency and of surely preventing degradation of electrodes during the state where the fuel cell system is not generating the electric power, irrespective of repeated start-up and stop.

Abstract: A fuel cell system includes a fuel cell stack, a fuel inlet conduit, a water inlet conduit, and a hydrometer, such as an alcoholometer. The hydrometer is adapted to provide a measurement of a water-to-fuel ratio of a fuel inlet stream within the fuel inlet conduit. The water inlet conduit is adapted to provide a quantity of water to the fuel inlet conduit in order to achieve a desired water-to-ratio being provided to the fuel cell stack.

Abstract: A fuel cell system includes (1) a fuel containing unit having two containers containing a metal hydride, the two containers being disposed in thermal contact with each other, (2) a fuel cell disposed in thermal contact with one of the two containers, (3) a discharge regulating valve capable of switching between a suppressed state in which hydrogen discharge from the other of the two containers is suppressed and an open state in which the suppressed state is canceled, and (4) a control unit for controlling the discharge regulating valve so that the suppressed state is set when the temperature inside the other container is less than a predetermined temperature and the open state is set when the temperature inside the other container is greater than or equal to the predetermined temperature.

Abstract: A fuel cell system is provided with a fuel cell (20) which generates electricity by a chemical reaction between a fuel gas supplied to an anode side of the fuel cell and an oxidization gas supplied to a cathode side of the fuel cell; estimating means (50) for estimating whether there is a possibility that a chemical short is occurring in the fuel cell when supply of the fuel gas and the oxidization gas to the fuel cell is stopped; and scavenging means (12) for supplying a scavenging gas to the cathode side when it has been estimated that there is a possibility that the chemical short is occurring.

Abstract: A flow control assembly for use in a fuel cell system, comprising a sensor for sensing hydrogen concentration in one of anode exhaust leaving an anode side of the fuel cell system and a gas derived from the anode exhaust, and a fuel flow control assembly for controlling the flow of fuel to the anode side of the fuel cell system based on the hydrogen concentration sensed by the sensor.

Abstract: A fuel cell includes electromotive portions, a first sheet, a second sheet, a replenishing portion and a fuel adjusting film. The electromotive portions cause fuel and oxygen to react chemically with each other to produce electrical energy. The first sheet is provided to supply the fuel to the electromotive portions. The second sheet is provided to supply the oxygen to the electromotive portions. The replenishing portion is provided at a predetermined portion of the first sheet to replenish the first sheet with the fuel. The fuel adjusting film is inserted in the first sheet to adjust the amounts of the fuel to be supplied from the first sheet to the electromotive portions.

Abstract: A variable capacity compressor that is operable in a normal mode and either an upward or downward rapid transient mode includes a compressor that compresses a fluid and a motor that drives the compressor. A controller powers the motor from a main power source when operating in the normal mode and powers the motor from a supplemental power source when operating in the upward rapid transient mode.

Abstract: A fuel cell system (10) of the present invention has a fuel cell (20) which generates electric power by being supplied with reactive gas, an air compressor (C1) which supplies oxidizing gas to the fuel cell (20), a pressure sensor (P2) which detects the pressure of oxidizing gas, a pressure control valve (C2) which adjusts the pressure of oxidizing gas, and a control device (50) which adjusts the valve opening of the pressure control valve (C2) on the basis of the pressure detected by the pressure sensor (P2). When an abnormality in the pressure sensor (P2) is detected, the control device (50) opens the pressure control valve (C2) so that the valve opening thereof is equal to or larger than a predetermined opening. This arrangement ensures that the cell operation can be continued for a while instead of being immediately stopped in the event of abnormality in the pressure sensor (P2).

Abstract: A method for adaptively controlling a fuel delivery injector in a fuel cell system, including determining a feed-forward bias for the fuel delivery injector, determining an injector flow set-point for the fuel delivery injector, monitoring stack current, determining a transient pressure correction for the stack and correcting the injector flow set-point.

Abstract: A fuel cell system includes a first shut valve capable of shutting off a gas flow in a gas path where a fuel cell gas flows; and a second shut valve arranged more towards the downstream side of the gas flow than the first shut valve, and capable of shutting off the gas flow. In each of the first shut valve and the second shut valve, sealing is performed by intimate contact between a movable member and a seal member and a gas pressure supplied from the upstream applies a force to the movable member to bring it into intimate contact with the seal member. A deformation degree by an external force of the same intensity is set greater in the seal member of the second shut valve than in the seal member of the first shut valve.

Abstract: A system and method for starting up a fuel cell system are disclosed. Briefly described, an embodiment for starting an electrochemical reaction between a fuel and an oxidant during a start-up process includes a fuel cell stack operable to output a nominal voltage during a normal operating condition and operable to output a reduced start-up voltage during the start-up process, and includes at least one balance of plant (BOP) device that supports operation of the fuel cell stack, operable at a nominal output when sourced by the fuel cell stack at the nominal voltage, and operable at a reduced output when sourced by the fuel cell stack at the reduced start-up voltage.

Abstract: There are provided a power generation unit, a fuel tank, a line, a mixing tank, a fuel circulation unit which circulates a mixture fuel from the mixing tank to the mixing tank via the power generation unit and the line, a fuel supplier which supplies the fuel from the fuel tank to the mixing tank, an air supplier which supplies air to a cathode, a power adjustment unit which adjusts the current applied to the load in accordance with a generated power output, a fan which adjusts the temperature of the power generator, and a control unit which detects the concentration and volume of the mixture fuel and manipulates, on the basis of a detection result, the fuel circulation unit, the fuel supplier, the load of the power adjustment unit, the air supplier and the fan to control the concentration and volume of the mixture fuel.

Abstract: Active metal fuel cells are provided. An active metal fuel cell has a renewable active metal (e.g., lithium) anode and a cathode structure that includes an electronically conductive component (e.g., a porous metal or alloy), an ionically conductive component (e.g., an electrolyte), and a fluid oxidant (e.g., air, water or a peroxide or other aqueous solution). The pairing of an active metal anode with a cathode oxidant in a fuel cell is enabled by an ionically conductive protective membrane on the surface of the anode facing the cathode.

Abstract: A high-pressure fluid supply apparatus that avoids gas leakage due to a reduction in the performance of a seal member provided inside piping is provided. A high-pressure fluid supply apparatus is provided, the apparatus including: piping that supplies a fluid from a high-pressure fluid supply source to a fluid utilizing device via a first valve device and a second valve device; a seal member that is arranged at a pipe part between the first and second valve devices in order to maintain sealing property of the pipe part, the seal member being made of an elastic material; and a control unit that controls closing and opening of the first and second valve devices to be able to adjust a pressure variation rate of the fluid in the pipe part, wherein the control unit adjusts the pressure variation rate in accordance with a temperature of the seal member.

Abstract: Embodiment of a system for generating electric power with micro fuel cells comprising at least one first micro cell and at least one second micro cell, each micro cell having an anode and a cathode with a membrane being sandwich-wise interposed, the system comprising a spacer element having an annular element that surrounds a cavity, said spacer element being associated with said anode of said first micro cell and with said anode of said second micro cell to realize a common diffusion chamber for the fuel of said first micro cell a of said second micro cell.

Abstract: A stack (10) of fuel cells (11) is to be tested for tightness of the fuel cell membranes. For this purpose, a tracer gas is introduced into the fuel feed channel (15) of the stack (10). The fuel discharge channel (16) is either open or it is closed. A carrier gas is fed to the feed air channel. (17) and led through the exhaust air channel (18) to a gas sensor (28) where a determination is made whether the carrier gas contains amounts of tracer gas. A defective fuel cell (11) can be located by introducing a lance comprising a sniffing probe into the corresponding channel (18) and determining the position of the probe.

Abstract: Fuel cell separation, fuel cell device, and electronic applied device technical field are provided. A fuel cell separator capable of making a fuel cell device compact and reducing variations in air supply amount to generating cells. Oscillating fans as fluid oxidant supplying means are respectively provided at openings of channels. The oscillating fans are individually driven to respectively supply air into the channels. The oscillating fans are included in a separator body of a separator. As compared with the case that the oscillating fans are provided separately from a fuel cell body having the separator as a component, the limitation to layout of the fuel cell body and various units for effecting stable electric power generation in the fuel cell body can be reduced, and the fuel cell device can be reduced in size.

Abstract: A fuel cell includes a fuel cell stack, a buffer, an actuator, and a control circuit. The control circuit controls the operation of the actuator according to a reference value of a reference volume of fuel disposed in the buffer. The fuel cell is operated by measuring a value corresponding to a volume of fuel disposed in the buffer, comparing the value with a reference value, and operating the actuator according to a result of the comparison.

Abstract: A fuel-cell system is provided, which includes a fuel cell, a reactive-gas supply unit and a control unit. The reactive-gas supply unit supplies the reactive gases to the fuel cell. The control unit includes an average stoichiometric flow-ratio calculation part and a reactive-gas reduction part. The average stoichiometric flow-ratio calculation part calculates an average stoichiometric flow ratio by averaging stoichiometric flow ratios. A stoichiometric flow ratio is a ratio of an amount of the reactive gases supplied to the fuel cell with respect to a required amount of the reactive gases of the fuel cell in accordance with a required amount of power generation. When the average stoichiometric flow ratio is equal to or greater than a first predetermined value, the reactive-gas reduction part reduces the amount of the reactive gases supplied to the fuel cell so as to lower the stoichiometric flow ratio.

Abstract: A solid oxide fuel cell system includes at least one fuel cell and at least one gas flow channel to deliver a reactant mixture. The fuel cell comprises at least one chamber to house at least one anode, at least one cathode, and at least one electrolyte, and the fuel cell is adapted to receive a reactant mixture comprising reactants mixed prior to delivery to the fuel cell. The one or more gas flow channels for delivering the reactant mixture have characteristic dimensions that are less than a quench distance of the reactant mixture at an operating temperature within the solid oxide fuel cell system.

Abstract: The electric power source comprises a fuel cell and at least one flow channel the inlet and outlet whereof are respectively connected to a reactive fluid source and to a tank designed to contain the reactive fluid feeding the fuel cell and the water produced by the fuel cell. An inlet valve is arranged between the reactive fluid source and the inlet of the flow channel and is controlled by a control device. Once the tank has been filled with reactive fluid, the inlet valve is closed for a predetermined first time period. It is then opened for a predetermined second time period so as to evacuate the water accumulated in the fuel cell during the first time period to the tank, and to refill the tank with reactive fluid.

Abstract: A fuel cell system is disclosed with a fuel cell stack having a plurality of fuel cells, the fuel cell stack including an anode supply manifold and an anode exhaust manifold, a sensor for measuring at least one of an environmental condition affecting the fuel cell stack and a characteristic of the fuel cell stack, wherein the sensor generates a sensor signal representing the measurement of the sensor; and a processor for receiving the sensor signal, analyzing the sensor signal, and controlling a flow rate of a fluid flowing into the anode supply manifold based upon the analysis of the sensor signal.

Abstract: A fuel-cell flow regulator is placed in a fuel cell having two entrances, each of which is formed at one of two sides of the fuel cell. The fuel cell is composed of a plurality of single cells, each of which includes a fuel inlet and a fuel passage in communication with the fuel inlet. The fuel passages jointly define a fuel tunnel in communication with all of the entrances. The flow regulator is located at the fuel tunnel and movable back and forth along the fuel tunnel.

Abstract: A PEM based water electrolysis stack consists of a number of cells connected in series by using interconnects. Water and electrical power (power supply) are the external inputs to the stack. Water supplied to the oxygen electrodes through flow fields in interconnects is dissociated into oxygen and protons. The protons are transported through the polymer membrane to the hydrogen electrodes, where they combine with electrons to form hydrogen gas. If the electrolysis stack is required to be used exclusively as an oxygen generator, the hydrogen gas generated would have to be disposed off safely. The disposal of hydrogen would lead to a number of system and safety related issues, resulting in the limited application of the device as an oxygen generator. Hydrogen can be combusted to produce heat or better disposed off in a separate fuel cell unit which will supply electricity generated, to the electrolysis stack to reduce power input requirements.

Abstract: During a process of shutting down a fuel cell power plant (11) the exits (28) of the anodes (14) are vented (76-77) under liquid (57). The liquid may be that of a coolant accumulator (57) of a fuel cell stack (12) cooled by conduction and convection of sensible heat into liquid coolant (FIG. 1) or evaporatively cooled (FIG. 4). The vent (77) may be under liquid all of the time (FIGS. 1, 3 and 4) or only after the stack has been drained of coolant (FIG. 2). The vent (77) may be the only vent for the anode exits (FIG. 3), or there may also be a purge vent valve (31) (FIGS. 1 and 4).

Abstract: A control system for a direct alcohol fuel cell, comprising: a fuel tank; a fuel cell stack; a pump feeding the fuel in the fuel tank to the fuel cell stack; a switching mechanism connecting the pump selectively with the fuel and air in the fuel tank; and a control unit switching the switching mechanism to connect the pump with the air when stopping power generation of the fuel cell stack. When the generation of the fuel cell stack is stopped, feeding of the fuel to the fuel cell stack is stopped and the air is supplied to the fuel cell stack thereby pushing out the remaining fuel.

Abstract: A microbial fuel cell comprising a cathode module, an anode module, a means for feeding source water to the anode module, and a means for feeling air to the source water after said anode module, wherein the source water is introduced in the anode module and discharged at the cathode module, a membrane is not used to transfer electrons, and the source water does not flow through a layer between the cathode and anode modules, such as glass wool or beads.

Abstract: A gas control and operation method of a fuel cell system for improved water and gas distribution is disclosed. The present invention provides for a mechanization of a fuel cell system that allows control of the anode reactant and anode effluent through the anode portions of the fuel cell system to improve water and gas distribution on the anode side of the fuel cells that increases the voltage stability of the fuel cells.

Abstract: Control systems, sensors and methods for controlling the fuel concentration in a fuel cell or a fuel cell stack are provided. In certain examples, the control system may be configured to detect a performance degradation, and the fuel concentration provided to the fuel cell may be adjusted in response to detection of the performance degradation.

Abstract: A fuel-cell system 1 includes: a fuel cell 13 configured to generate electricity through reaction between hydrogen gas and air; a compressor 12 configured to supply air as a scavenging gas to a reactant gas path 13a of the fuel cell 13; a control part 18 configured to control an amount of air supplied from the compressor 12 to the fuel cell 13 to perform scavenging of the fuel cell 13; and pressure sensors P1 and P2 configured to monitor a pressure drop in the reactant gas path 13a of the fuel cell 13. The control part 18 controls an amount of supplied air so as to keep the pressure drop in the reactant gas path 13a substantially constant when the fuel cell 13 is scavenged. With this configuration, residual water can be suitably purged from the fuel cell while energy consumption is suppressed.

Abstract: A process for the generation of electricity and the production of a concentrated carbon dioxide stream using a molten carbonate fuel cell. Anode off-gas is at least partly fed to a catalytic afterburner wherein it is oxidized with an oxidant consisting of part of the cathode off-gas and/or part of a molecular oxygen containing external oxidant stream, which external oxidant stream has at most 20% (v/v) nitrogen. The oxidized anode off-gas is brought into heat exchange contact with the remainder of the cathode off-gas and the remainder of the external oxidant stream to obtain cooled anode off-gas and a heated mixture of cathode off-gas and external oxidant which are fed to the cathode chamber as the cathode inlet gas. As soon as a set point in the carbon dioxide concentration at the cathode chamber outlet is reached, part of the cooled anode off-gas is withdrawn from the process.

Abstract: A fuel cell system includes a branch anode gas supply pipe in which hydrogen before supplied to a fuel cell flows; and a branch cathode gas supply pipe in which air before supplied to the fuel cell flows. One end on the upstream side of the branch anode gas supply pipe is connected to the upstream side of a regulator in an anode gas supply pipe, and the other end thereof is connected to the branch cathode gas supply pipe via a hydrogen injector. The branch anode gas supply pipe is provided with a hydrogen regulator, which detects a pressure in the branch cathode gas supply pipe as a signal pressure.

Abstract: A fuel cell system including a fuel cell that generates electricity through an electrochemical reaction between a fuel gas and an oxidizing gas is provided with a gas supply unit that supplies each of the fuel gas and the oxidizing gas to an anode and a cathode of the fuel cell, respectively by quantity corresponding to a load, a gas permeation quantity estimation unit that estimates a gas permeation quantity of at least one of the fuel gas and the oxidizing gas between the anode and the cathode after the power generation performed by the fuel cell is stopped, and a correction unit that corrects a supply quantity of at least one of the fuel gas and the oxidizing gas each corresponding to the load in accordance with the estimated gas permeation quantity, which is to be supplied by the gas supply unit upon a subsequent start of power generation.

Abstract: The disclosure describes fuel cell systems including a fuel cell stack that generates electricity, an exhaust valve that externally vents a fuel gas from a fuel chamber of the fuel cell stack, and a controller that computes an estimated time to replace an oxidant gas in at least the fuel chamber with a newly supplied fuel gas, wherein at a time of starting-up the fuel cell system the controller maintains the exhaust valve in an open position for the estimated time.

Abstract: A method of controlling a fuel generating reaction of a fuel cell includes: a. providing a first reactant; b. activating the first reactant to generate fuel to the fuel cell; c. when a characteristic value of the fuel cell reaches a first reference value during the activation, adding a quantity of a second reactant to the first reactant to determine a monitoring time; d. after the monitoring time, detecting the characteristic value of the fuel cell to acquire a first characteristic value; e. if the first characteristic value is lower than the first reference value, performing step d.; f. if the first characteristic value is higher than the first reference value, detecting the characteristic value of the fuel cell to acquire a second characteristic value after a delay time; and g. if the second characteristic value is lower than the first reference value, proceeding to step d.

Abstract: A fuel cell system includes a fuel cell having a membrane, which is adapted to perform power generation by a chemical reaction of two reaction gases each supplied to one side of the membrane, reaction gas paths through which the two reaction gases flow, a purge device for purging at least one of the two reaction gases from the reaction gas paths, a monitoring device for monitoring a state of the fuel cell after stopping of the power generation in the fuel cell, and a control unit for controlling the purge device so as to carry out a purge operation when it is determined by the monitoring device that the state of the fuel cell is a predetermined state.

Abstract: A method for controlling cathode air flow at system start-up by controlling a stack by-pass valve. The method includes determining a concentration of hydrogen in a cathode side of the fuel cell system. The method also includes determining a volumetric flow rate through a cathode compressor, determining a volumetric flow rate through the stack cathode and determining a fraction of volumetric flow rate through the cathode to the total flow through the compressor. The method determines a modeled hydrogen outlet concentration from the fuel cell stack based on the volumetric flow rate through the compressor, the fraction of volumetric flow rate through the compressor to the total flow through the compressor and the concentration of hydrogen in the cathode. The method uses a desired fraction of volumetric flow rate through the cathode and the total flow through the compressor to determine the position of the by-pass valve.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. The fuel cell stack produces electric current at a production amperage. In some examples, a control system is adapted to control operation of the fuel cell stack based on a pressure detected at the fuel cell stack. In some examples, a target production amperage is determined based on the detected pressure, such that when electric current is produced at the target production amperage for the detected pressure, the fuel cell stack consumes a predetermined proportion of the supply fuel.

Abstract: The present invention relates to a direct oxidation fuel cell system including at least one electricity generating element including at least one membrane-electrode assembly which includes an anode and a cathode on opposite sides of a polymer electrolyte membrane, and a separator. The direct oxidation fuel cell generates electricity through an electrochemical reaction of a fuel and an oxidant. An oxidant supplier supplies the electricity generating element with the oxidant. A fuel supplier supplies the anode with a combination of fuel and hydrogen to provide improved power output.