Abstract: An electrochemical cell system including a plurality of electrochemical cells arranged in an electrochemical cell stack, the stack including a plurality of substacks configured such that fluid flows in series from substack to substack, a first electrical control device coupled to a first substack and a second electrical control device coupled to a second substack, wherein the first electrical control device is controllable independently of the second control device to selectively electrically configure the first and second substacks.

Abstract: A fuel cell system includes a fuel cell stack that includes a plurality of unit cells, each including a membrane-electrode assembly including an electrolyte membrane, a cathode at one side of the electrolyte membrane, and an anode at an opposite side of the electrolyte membrane, and separators at respective sides of the membrane-electrode assembly, a fuel supply for supplying a fuel to the fuel cell stack, an oxidizing agent supply for supplying an oxidizing agent to the fuel cell stack, and a controller for controlling operation of the fuel supply and the oxidizing agent supply, for measuring a voltage of each of the unit cells, and for turning off a load coupled to the fuel cell stack after determining that the voltages of the unit cells reached a reference voltage.

Abstract: A fuel cell system and method that enables warm-up power generation corresponding to the residual water volume in the fuel cell stack without using auxiliary devices for measuring the residual water volume in the fuel cell stack. A controller computes total generated electrical energy Q by integrating of the generated current detected by current sensor during the period from start-up to shutting down of the fuel cell system, and stores the result in total generated electrical energy storage part. Also, controller measures fuel cell temperature Ts at the last shutting down cycle with temperature sensor, and stores it in power generation shutting down temperature storage part.

Abstract: An exemplary fuel cell manifold seal retainer assembly includes a bracket and a retainer. The bracket is mountable to a manifold of the fuel cell stack. The retainer extends closer to a fuel cell stack then the manifold when the retainer is mounted to the bracket and when the bracket is mounted to the manifold. The retainer limits movement of a seal away from an installed position.

Abstract: A system and method for identifying leaks in a cathode sub-system of a fuel cell system. An air flow meter is provided up-stream of a compressor and monitors the air flowing into the compressor. When an air leakage diagnostic is commanded, a fuel cell stack by-pass valve and back-pressure valve are closed so that no air flows through or around the stack, and the recirculation valve is opened so that the air flows around the compressor. By knowing the leakage through the by-pass valve and the back-pressure valve, any flow above those values measured by the air flow meter gives an indication of air leakage out of the cathode sub-system components.

Abstract: A control device of a fuel cell system sets a required output of a fuel cell stack that is required according to a present power demand and predicts the required output and the current according to the temperature of the fuel cell stack from a predetermined output state map that is preset. The control device sets an operation state quantity according to the predicted current and the temperature of the fuel cell stack from a predetermined operation state quantity map that is preset. The control device includes at least one of a pressure at an air supply port of air that is supplied to the cathode electrode of the fuel cell stack, a utilization rate of the air at the cathode electrode, a flow rate of a cooling medium that cools the fuel cell stack, and humidity of the air at the air supply port as the operation state quantity.

Abstract: A fuel cell system of the present invention is a fuel cell system including a fuel cell and includes a medium circulation passage, a heat medium tank, a first circulator, a recovered water tank, a water circulation passage, a second circulator, a water purifier, a temperature detector, and a controller. The heat medium circulation passage and the water circulation passage are configured so as to realize heat exchange between a heat medium and water. The controller executes a circulation operation in which when the temperature detector detects a temperature lower than a first temperature capable of sterilizing microorganisms, the second circulator is caused to operate such that the temperature detected by the temperature detector becomes the first temperature or higher.

Abstract: In a fuel cell system, it is possible to suppress fixation of a fluid circulating device arranged in a fluid passage connected to a fuel cell main body. The fuel cell system is provided with a fuel cell stack, a system main body having respective elements for supplying a fuel gas and respective elements for supplying an oxidizing gas, and a control device. The control device includes a fluid circulating device drive processing unit having a function to forcibly drive the fluid circulating device after determining, based on a judgment related to one or more of a non-use time, an operation state of the system main body, a membrane impedance state of a fuel cell, a temperature of the fuel cell stack, and a background noise, whether or not forced driving to suppress sticking of the fluid circulating device is preferable at that time.

Abstract: A flow battery includes at least one electrochemical cell that has a first electrode, a second electrode spaced apart from the first electrode and a separator arranged between the first electrode and the second electrode. A first storage portion and a second storage portion are respectively fluidly connected with the at least one electrochemical cell. A first liquid electrolyte and a second liquid electrolyte are located in the respective first storage portion and second storage portion. The first electrode has an area over which it is catalytically active with regard to the first liquid electrolyte and the second electrode has an area over which it is catalytically active with regard to the second liquid electrolyte such that the area of the first electrode is greater than the area of the second electrode.

Abstract: Disclosed method of load-following operation of fuel-cell system comprises pre-determining functions F=f(P) and P=f?1(F), wherein P is the electric output and F is the fuel flow-rate required to output P. If reformable flow-rate FR<Fmin (the minimum flow-rate value), power generation is stopped. If FR?Fmin and if required output PD?maximum power output PM, (1) is performed; and if FR?Fmin and if PD>PM, (2) is performed. (1) If f(PD)?FR, the output is set at PD, and the fuel flow-rate is set at f(PD); and if f(PD)>FR, the output is set at the maximum value of P lower than PD and computed using P=f?1(FR), and the fuel flow-rate is set at FR. (2) If f(PM)?FR, the output is set at PM, and the fuel flow-rate is set at f(PM); and if f(PM)>FR, the output is set at the maximum value of P computed using P=f?1(FR), and fuel flow-rate is set at FR.

Abstract: A fuel cell system for generating a hydrogen test pulse includes a fuel cell stack having an anode inlet in fluid communication with a hydrogen source via a fuel spending line, a cathode inlet in fluid communication with an oxidant source, and an anode outlet and a cathode outlet in fluid communication with an exhaust line. An electric pressure regulator is in fluid communication with the fuel spending line. An overpressure valve is in fluid communication with an overpressure line, which is in fluid communication with the fuel spending line between the electric pressure regulator and the fuel cell stack. A hydrogen sensor is in communication with the exhaust line, and is configured to measure the hydrogen test pulse.

Abstract: The disclosure is directed at a method and apparatus for controlling fuel cell operating characteristics. In certain situations, the operating efficiency of fuel cells is degraded to external conditions. Providing a method and apparatus to control operating conditions for the fuel cell assists in improving the operating efficiency. This can be achieved by controlling certain environmental conditions, such as temperature and relatively humidity, in the area surrounding the fuel cell.

Abstract: A fuel cell system that is able to perform power generation more stably than in the past regardless of external environment is provided. Based on a temperature of a power generation section detected by a temperature detection section, a supply amount of a liquid fuel from a fuel pump is adjusted, and therefore control in which the temperature of the power generation section becomes constant is performed. In addition, a fuel cell system that is able to perform power generation in a vaporization supply type fuel cell more stably than in the past is provided. A level of a power generation voltage supplied from the power generation section is raised by a boost circuit. In a control section, operation of the boost circuit is controlled using a given control table, and therefore control is performed on an output voltage and an output current supplied from the boost circuit to a load.

Abstract: A method and system for supplying power to a portable electronic device includes supplying current from one or more fuel cells to a DC-DC converter and regulating a current limit of the DC-DC converter as a function of a measured temperature of at least one of the power supply system and the portable electronic device. The current limit can vary as an inverse function of the measured temperature. The current limit can be an input current limit of the DC-DC converter or an output current limit of the DC-DC converter. Current produced by the one or more fuel cells can decrease proportionally to a decrease of the current limit of the DC-DC converter, reducing the heat produced by the one or more fuel cells and thereby reducing the measured temperature. A temperature sensor can be located on or near the one or more fuel cells. A temperature sensor can be located on an internal housing of the portable electronic device.

Abstract: A system and method for utilizing a pressurized volume of oxygen in a cathode plumbing of a fuel cell system. The system and method includes calculating an air/oxygen balance that is based on an air balance and an oxygen balance in the cathode plumbing. The system and method further include determining the number of moles of oxygen available for fuel cell chemical reactions using the calculated air/oxygen balance and drawing current from a fuel cell stack using the moles of oxygen available for fuel cell chemical reactions.

Abstract: A fuel cell vehicle is provided that can perform communicative filling only in a case in which it is possible to perform communicative filling appropriately. The vehicle includes: a pressure sensor and temperature sensor; a communication system that transmits data signals generated based on the outputs of these sensors; a battery; a lidded box that protects a hydrogen feed port; a lid switch; and a communicative filling ECU that activates the communication system after the lid has been opened. The ECU determines, based on the state of an activation prohibited flag, whether being a state in which activation of the system is not permitted in response to an opened-state of the lid having been detected. The ECU does not activate the system in a case of the flag being ON, and activates the system in a case of the flag being OFF.

Abstract: A fuel cell power plant includes a cell stack assembly having an anode and a cathode. A component is arranged in fluid connection with at least one of the anode and cathode. The component has a first shut-down cooling rate. A heat exchanger is arranged in fluid communication with and between the component and one of the anode and cathode. The heat exchanger has a second shut-down cooling rate greater than the first shut-down cooling rate. Water vapor within the fuel cell power plant outside of the cell stack assembly will condense and freeze in the heat exchanger rather than the component, avoiding malfunction of the component upon start-up in below freezing environments.

Abstract: A method for starting a cold or frozen fuel cell stack as efficiently and quickly as possible in a vehicle application is based upon a state of charge of a first power source such as a high voltage battery. Power flow between the first power source and fuel cell system is coordinated in conjunction with a specific load schedule and parallel control algorithms to minimize the start time required and optimize system warm-up.

Abstract: The fuel cell system is simplified and made more compact while providing the favorable recirculation of hydrogen-containing off-gas regardless of the increase or decrease in its flow rate. The fuel cell system is provided with: a cell unit that generates electricity by means of separating hydrogen-containing gas and oxygen-containing gas from each other while placing in flow contact to each other; and a recirculation mechanism for recirculating to the cell unit hydrogen-containing off-gas discharged from the cell unit. The fuel cell system has a flow rate determination unit that determines whether or not the hydrogen-containing gas fed to the cell unit is less than a predetermined flow rate; and a gas feeding pressure varying mechanism that cause the pressure of the hydrogen-containing gas to vary to increase and decrease when it is determined that the hydrogen-containing gas fed to the cell unit is less than the predetermined flow quantity.

Abstract: A fuel cell system that determines the concentration of hydrogen gas in an anode loop. The fuel cell system includes at least one fuel cell, an anode inlet, an anode outlet, an anode loop, a source of hydrogen gas and an injector for injecting the hydrogen gas. First and second pressure sensors are provided in the anode loop and are spaced a known distance from each other. A controller responsive to the output signals from the first and second pressure sensors filters the sensor signals from the first and second pressure sensors and determines the concentration of hydrogen gas in the anode loop based on the time difference between the filtered sensor signal from the first pressure sensor and the filtered sensor signal from the second pressure sensor.

Abstract: The present invention provides a fuel cell hybrid system having a multi-stack structure, which maintains the voltage of a fuel cell at a level lower than that of an electricity storage means (supercapacitor) during regenerative braking so that the fuel cell does not unnecessarily charge the electricity storage means, thereby increasing the amount of recovered energy and improving fuel efficiency.

Abstract: A fuel cell is operated with high power such that which a humidified gas and a dry gas are selectively supplied as oxidant to a cathode of the fuel cell. This method includes (S1) supplying a humidified gas while a power is constantly maintained or until the power begins to decrease; (S2) after supplying the humidified gas, supplying a dry gas to obtain a greater power than an average power of the step (S1); and (S3) after obtaining a predetermined power in the step (S2), repeatedly supplying a humidified gas in case the power decreases and supplying a dry gas in case the power decreases again afterwards, thereby increasing the power such that the predetermined power is maintained. This method provides an optimal operating condition to a fuel cell, thereby ensuring a high power.

Abstract: An electrical power source for a portable electronic device. The electrical power source includes at least one fuel cell adapted to receive fuel and generate therefrom electrical power for powering at least one component of the portable electronic device, a fuel tank adapted to provide fuel to the fuel cell, and at least one thermoelectric module in thermal contact with at least one of the fuel cell and fuel tank for regulating the temperature of the at least one fuel cell and at least one fuel tank.

Abstract: The present invention provides an apparatus and method for generating a virtual sound source for monitoring the operating state of a fuel cell stack, which monitors in real time the deviation and deterioration of a plurality of cells in a fuel cell stack during operation, and expresses the results as a chord or different sounds, thus allowing a driver to easily recognize the operating state of the fuel cell stack

Abstract: A fuel system including a fuel cell including a plurality of unit cells supplied with a prescribed gas to generate electricity, a stoichiometric ratio calculating apparatus calculating the stoichiometric ratio of the prescribed gas for each unit cell, and a gas flow increasing apparatus increasing the supply of the prescribed gas when the stoichiometric ratio falls below a prescribed value.

Abstract: A solid electrolyte fuel cell system includes a reformer to produce a hydrogen-rich reformed gas from fuel, oxygen and water, and a stack structure including a stack of fuel cell units each receiving supply of the reformed gas and air, and producing electricity. The fuel cell system further includes a reformed gas cooler to cool the reformed gas supplied from the reformer to the stack structure, and a temperature control section to control operation of the reformed gas cooler in accordance with an operating condition such as a request output of the stack structure. The reformed gas cooler includes a device such as a heat exchanger for cooling the reformed gas with a coolant such as air.

Abstract: A fuel cell system for a vehicle includes a fuel cell, a fuel supply device, an oxidizer supply device, an anode potential measuring device, and a discharge controller. The anode potential measuring device is configured to measure an anode potential of an anode. The discharge controller is configured to control discharge of electric current from the fuel cell as part of a process of stopping the fuel cell during idling of the vehicle. When receiving idle stop permission for the fuel cell, the discharge controller determines whether the fuel cell is permitted to discharge. When the anode potential is equal to or lower than a predetermined threshold value, the discharge controller permits the fuel cell to discharge. When the anode potential is higher than the predetermined threshold value, the discharge controller does not permit the fuel cell to discharge.

Abstract: A fuel cell apparatus includes a fuel cell generating electric power, and including a fuel electrode which includes an anode catalyst, which is disposed in one side of an electrolyte membrane, which is supplied with liquid fuel, and which discharges gas generated by a chemical reaction accelerated by the anode catalyst, and an oxidizing agent electrode which includes a cathode catalyst, which is disposed in the other side of the electrolyte membrane, and which is supplied with air, and a control unit controlling a load applied to the fuel cell. The control unit increases the load in at least one of two cases, one case being when electric power generated by the fuel cell lowers below a predetermined reference value and another case being at predetermined time intervals, and stops the increase of the load after elapsing a predetermined time period from the start of the increase of the load.

Abstract: A fuel cell system including a fuel cell, a reformer, a combustor that heats the reformer using anode off-gas of the fuel cell as a fuel, and a ratio controller that controls a ratio of a combustion component supplied to the combustor in accordance with a temperature distribution in a gas flow direction inside the combustor.

Abstract: In a fuel cell system, when an electric current drawn from fuel cells is controlled based on a target power generation value, an upper limit of the electric current is optimally set to make suspensions of operation caused by voltage drops to be as infrequent as possible. The upper limit of the electric current is set by adding a predetermined offset value (e.g., 2 A) to an average value of the electric current before a predetermined delay time (e.g., 10 seconds). Moreover, when the electric current drawn from the fuel cells is controlled based on a target power generation value, the value of the electric current is compared with the upper limit of the electric current, to control the electric current.

Abstract: A method for operating a fuel cell system during an interruption includes identifying a load interruption in which an external load is partially or fully unable to draw electrical power from the fuel cell system. At least a first fuel cell column of the fuel cell system is operated in an electrolysis mode such that the first fuel cell column generates fuel during the load interruption. Power is provided to the first fuel cell column in the electrolysis mode from at least a second fuel cell column of the fuel cell system. The second fuel cell column is operating in a normal power generation operating mode.

Abstract: A fuel cell system includes a first heating mechanism and a second heating mechanism. The first heating mechanism directly heats a reformer using some of an exhaust gas discharged from a fuel cell stack. The second heating mechanism supplies the remaining exhaust gas to a heat exchanger and indirectly heats the reformer by the heat generated in the heat exchanger. The reformer performs preliminary reforming to produce a reformed gas. The reformed gas is supplied to an anode. At the anode, water produced in the power generation is present as a water vapor. The reformed gas is further reformed by steam reforming to produce a hydrogen gas.

Abstract: A fuel cell system including a fuel cell, and a converter which is connected between the fuel cell and a high voltage system and which sets an output ceiling voltage of the fuel cell, the fuel cell system comprising fuel gas supply stopping means for stopping the supply of fuel gas to the fuel cell in an intermittent operation mode, remaining fuel gas amount determination means for determining whether fuel gas in at least an amount capable of generating power remains in the fuel cell, converter driving means for driving the converter so that, when it is determined that fuel gas in at least the amount capable of generating power remains in the fuel cell, the output ceiling voltage of the fuel cell becomes a first voltage capable of preventing deterioration of the fuel cell, and converter stopping means for stopping the converter when it is determined that fuel gas in at least the amount capable of generating power does not remain in the fuel cell.

Abstract: A fuel cell system includes a fuel cell stack for receiving a supplied reactant gas to generate a power; an air compressor for removing moisture remaining in the fuel cell stack during the stop of the power generation; a secondary cell for supplying an operative power to the air compressor; and a controller for controlling the balance of water flowing into and out of the fuel cell stack so that a time required to remove the moisture remaining in the fuel cell stack by the air compressor is substantially constant.

Abstract: Thermal and hydration management systems and methods for fuel cell systems, including control of electrolytic membrane hydration levels. In some embodiments, the thermal properties of the fuel cell are controlled based on a variable associated with the oxidant supply stream and/or a variable associated with the fuel cell energy output. In some embodiments, the temperature of the fuel cell is controlled based on the temperature of the oxidant supply stream. In some embodiments, the temperature range across the fuel cell stack is controlled based on the flow rate of the oxidant stream and the electrical output generated by the fuel cell stack. In some embodiments, the humidity within the fuel cell stack is controlled. In some embodiments, the liquid water content of the cathode exhaust stream is controlled.

Abstract: A fuel cell system capable of improving the voltage controllability of a converter provided in the system is provided. A controller judges whether or not a passing power of a DC/DC converter falls within a reduced response performance area for the number of active phases as of the present moment. When the controller determines that the passing power of the DC/DC converter falls within the reduced response performance area, the controller determines the number of phases which avoids the driving within the reduced response performance area, and outputs a command for switching to the determined number of phases (phase switching command) to the DC/DC converter.

Abstract: A system and method for controlling hydrogen gas flow to an anode side of a fuel cell stack using a pressure regulator in the event that an injector that normally injects the hydrogen gas into the fuel cell stack has failed in a stuck open position. During normal operation, the control of the injector is determined based on the pressure of an anode sub-system and the position of the pressure regulator is determined based on a supply pressure between the pressure regulator and the injector. If it is determined that the injector is stuck in an open position, then the position of the pressure regulator is controlled to the anode pressure instead of the supply pressure. If the pressure regulator is an electrical pressure regulator, then it is pulsed to mimic normal system operation. Alternately, another valve, such as a shut-off valve, can be employed to provide the flow pulsing.

Abstract: A fluid supply system includes a fluid supply source, a first valve unit, a second valve unit, a first pressure detector, a second pressure detector, a third pressure detector, and a controller. If the pressure detected by the third pressure detector is less than a shutoff pressure at a timing of starting supply of fluid from the fluid supply source, the controller calculates a pressure equalization time from a timing at which opening of a pilot valve is completed to a timing at which a main valve starts closing, based on the pressures detected by the first pressure detector, the second pressure detector and the third pressure detector, sets a valve-open waiting time based on the pressure equalization time, and controls opening of the second valve unit upon elapse of the valve-open waiting time after controlling opening of the first valve unit.

Abstract: A cathode for use in a direct oxidation fuel cell (DOFC) comprises a gas diffusion medium (GDM) including a backing layer and a microporous layer comprising a fluoropolymer and an electrically conductive material, wherein loading of the fluoropolymer in the microporous layer is in the range from about 10 to about 60 wt. %. In use, a concentrated solution of a liquid fuel is supplied to an anode and an oxidant to the cathode of the fuel cell, and the fuel cell may be operated at a low oxidant stoichiometry ?c not greater than about 2.5.

Abstract: A circuit connection control system of a fuel cell includes a point connection portion to which an anode current collecting portion and a cathode current collecting portion of each unit cell are electrically connected, a voltage measuring unit that measures an output voltage of each unit cell, a switching unit connecting the anode current collecting portions and the cathode current collecting portions of the plurality of unit cells at the point connection portion; and a DC-DC converter that converts a voltage generated from the fuel cell to a predetermined voltage. A method of operating the circuit connection control system includes measuring an output voltage of each unit cell; detecting a first unit cell showing an output voltage lower than a predetermined first voltage; and connecting the first unit cell in parallel to a second unit cell.

Abstract: The invention relates to a fluid delivery head for an electrochemical cell, for example a fuel cell. The delivery head combines the inlets and outlets of the lines for delivering the fluids, notably hydrogen and oxygen. The hydrogen delivery line feeds an active part of the fuel cell and includes a cavity in communication with a discharge pipe via a solenoid valve. The invention performs several functions with a minimum of elements and with reduced bulk.

Abstract: According to a first aspect, the present invention relates to a method of controlling a fuel cell, comprising a step of controlling the fuel cell electric efficiency per unit of active surface area by checking and/or adjusting the current density produced in the fuel cell per unit of active surface area. According to another aspect, the present invention concerns a fuel cell suitable for obtaining an electric power output, which comprises, among the other things, control means of the electric efficiency of the fuel cell including means suitable for checking and/or adjusting the current density produced in the fuel cell per unit of active surface area.

Abstract: Provided is a fuel-cell system and a method of operating the fuel-cell system, wherein functions F=f(P) and P=f?1(F) of electrical output P and fuel flow-rate F required to output P are beforehand obtained, and a reformable fuel flow-rate FR is calculated from the temperature of reforming catalyst layer. When FR?Fmin, if the output demand PD?maximum output PM, and when f(PD)?FR, F is set to f(PD); and when f(PD)>FR, the P is set to the maximum value within a range of less than PD amongst P calculated from P=f1(FR), and F is set to FR. When PD>PM, and when f(PM)?FR, the cell output is set to PM, and F is set to f(PM). When f(PM)>FR, the cell output is set to the maximum value amongst P calculated from P=f1(FR), and F is set to FR.

Abstract: The present invention provides a fuel cell system capable of accurately controlling the pressure of fuel gas supplied to the fuel cell, the fuel cell system comprising: a fuel gas supply line (SL) which supplies the fuel gas from a fuel gas supply source (11) to the fuel cell (10); pressure-regulating means (RG) provided on the fuel gas supply line (SL) and for regulating the pressure of the fuel gas supplied from the fuel gas supply source (11); and a circulation route (R) which returns the fuel gas discharged from the fuel cell (10) to the fuel gas supply line (SL), wherein the circulation route (R) is connected to the fuel gas supply line (SL) such that the fuel gas is returned thereto in the upstream of the pressure-regulating means (RG).

Abstract: A fuel cell power generation system including a fuel cell, a fuel generator, an oxidizing gas supply device, an output controller, an open-close mechanism, and a controller. The controller is configured such that in a stop process, the controller controls the output controller to stop supplying the electric power to an external load; controls the oxidizing gas supply device to stop supplying an oxidizing gas and controls the open-close mechanism to close a passage upstream from an oxidizing gas channel; after the passage upstream from the oxidizing gas channel is closed, stops a raw material gas supply device and a water supply device when a predetermined period has elapsed, during which period a gas in the oxidizing gas channel is replaced by a fuel gas.

Abstract: The invention provides a fuel supply control system for fuel cells, controlling fuel concentration in a fuel unit. The fuel supply control system comprises a first thermal meter detecting a system temperature of the fuel cell, a fuel supply device comprising a fuel tank storing highly concentrated fuel and a fuel deliver device delivering fuel from the fuel tank to the fuel unit to adjust fuel concentration thereof, and a controller calculating a difference between a predetermined and an environmental temperature, generating a first velocity by adjusting the predetermined fuel supply velocity according to the temperature difference, and setting the delivery velocity of the fuel delivering device according to the first velocity.

Abstract: A method that employs a model based approach to determine a maximum anode pressure set-point based on existing airflow in the exhaust gas line. This approach maximizes anode flow channel velocity during bleed events while meeting the hydrogen emission constraint, which in turn increases the amount of water purged from the anode flow channels to increase stack stability.

Abstract: An electrochemical cell system is provided having: at least one electrochemical cell stack, each stack having at least one reactant fluid inlet; a pressure transmitter arranged in the at least one reactant fluid inlet of each stack; and a control unit for regulating the electrochemical cell system, the control unit receiving at least one signal value from the pressure transmitter indicative of the reactant fluid pressure. The control unit may compare the at least one signal value with a stored values and generate a leak indication based on the rate of pressure decay within the electrochemical cell system. A method of detecting and indicating a leak is also disclosed.

Abstract: A system and method for recovering fuel cell stack voltage loss through humidification control. The method includes determining a rate of contamination addition to a surface of a fuel cell electrode in the fuel cell stack and determining a rate of contamination removal from the surface of the fuel cell electrode. The method compares the rate of contamination addition to the rate of the contamination removal to determine whether contaminant surface coverage of the electrode is increasing or decreasing and, if increasing, determines whether the amount of contamination of the electrode is above a predetermined value, where, if so, stack reconditioning through wet stack operation may be performed.

Abstract: A method of operating a high temperature fuel cell system containing a plurality of fuel cell stacks includes operating one or more of the plurality of fuel cell stacks at a first output power while operating another one or more of the plurality of the fuel cell stacks at a second output power different from the first output power.