A fuel cell system includes a first temperature sensor to detect a valve temperature of a sealing valve. A second temperature sensor is provided in a refrigerant circulation circuit to detect a fuel cell temperature of a fuel cell through a refrigerant. The circuitry is configured to calculate a sealing valve estimated temperature by subtracting a correction value from the fuel cell temperature detected by the second temperature sensor after the fuel cell stops generating electric power and after the sealing valve is closed. The circuitry is configured to determine whether at least one of the valve temperature and the sealing valve estimated temperature is lower than a predicted freezing temperature. The circuitry is configured to open the sealing valve when it is determined that the at least one of the valve temperature and the sealing valve estimated temperature is lower than the predicted freezing temperature.

A water management method for a fuel cell stack (FCS) is provided. The method may include outputting via a controller an FCS anode port estimated relative humidity value based on consumption of reactants and generation of products in the FCS and adjusting a humidification control strategy based on the value. The outputting may be in response to occurrence of a predicted FCS anode port relative humidity value from a model of a hydrogen recirculation system (HRS) of the FCS being within a predefined range. A fuel cell vehicle including a HRS and a controller is also provided. The HRS may include an ejector and a fuel cell stack having an anode port. The controller may be configured to activate a HRS model to calculate a real-time estimate of a relative humidity of the anode port based on an estimated flow rate of a secondary nozzle of the ejector.

A recirculation fuel cell device, which can be utilized on a submarine, may include a fuel cell with an anode side and a cathode side, wherein both the anode and cathode sides have input and output sides. The device may include a first inlet for oxygen and a second inlet for hydrogen. The device may further include a cathode-side connection between the output side of the cathode side and the input side of the cathode side, and an anode-side connection between the output side of the anode side and the input side of the anode side. A water separator may be disposed in the cathode-side connection, and a gas discharge valve for a continuous release of process gases may be disposed on the output side of the cathode side of the fuel cell. Operation of the device may involve recirculating an anode gas stream in its entirety.

A fuel cell system includes a fuel cell, a first combustor, a second combustor, a first heating gas return channel, a second heating gas return channel and a gas supplier. The fuel cell includes a solid electrolyte cell with an anode and a cathode. The first combustor supplies a heating gas to the cathode. The second combustor supplies a heating gas to the anode. The first heating gas return channel is arranged to mix at least some exhaust gas discharged from the cathode with the heating gas from the first combustor. The second heating gas return channel is arranged to mix at least some exhaust gas discharged from the cathode with the heating gas from the second combustor. The gas supplier is connected to the first heating gas return channel for supplying the exhaust gas from the cathode to mix with the heating gas of the first combustor.

A system and method for controlling a temperature of a fuel cell stack are provided. The method includes performing a pump OFF mode which turns off the cooling water pump or operates the cooling water pump while reducing the rotation speed of the cooling water pump to be less than the reference rotation speed, when a cooling water outlet temperature is equal to or less than a preset first temperature while a pump normal mode which adjusts a rotation speed of a cooling water pump to be equal to or greater than a preset reference rotation speed and varies rpm based on the cooling water outlet temperature is performed. In addition, the pump normal mode is performed when a cooling water outlet temperature estimation value of the fuel cell stack exceeds a preset second temperature while the pump OFF mode is performed.

A method for operating a fuel cell system comprises: feeding an oxidation gas stream to a cathode inlet of a cathode of a fuel cell of the fuel cell system; feeding a cathode exhaust gas stream from a cathode outlet of the cathode to an exhaust gas inlet of the humidifier; discharging the cathode exhaust gas stream from the humidifier via an exhaust gas outlet of the humidifier; humidifying the oxidation gas stream in the humidifier by means of the water extracted from the cathode exhaust gas stream; determining at least one of the following indicators for the moisture content of the cathode exhaust gas: a pressure drop between the cathode inlet and the cathode outlet, a pressure drop between the exhaust gas inlet and the exhaust gas outlet of the humidifier, a first temperature difference of the cathode exhaust gas stream between the exhaust gas inlet and the exhaust gas outlet of the humidifier, a second temperature difference of the oxidation gas stream between the oxidation gas inlet and the oxidation gas outlet of the humidifier, and varying a moisture feed to the cathode inlet and/or moisture removal from the cathode by adjusting at least one operating parameter of the fuel cell system on the basis of the at least one determined indicator.

A method for operating a solid oxide fuel cell having cathode-anode-electrolyte units, each including a first electrode for an oxidizing agent, a second electrode for combustible gas, and a solid electrolyte there between forming a metal interconnection between the CAE-units. The interconnect including a combustible gas distribution structure, and a second metallic gas distribution element having two channels for the oxidizing agent and separate channels for a tempering fluid. Cooling the second gas distribution element and a base layer of the first gas distribution element with the tempering fluid (O2). Measuring the first and second control temperatures T1 and T2. T1 being the tempering fluid temperature entering the fluid inlet side of the fuel cell. T2 being the tempering fluid temperature leaving the second gas distribution element. Where the amount of tempering fluid supplied to the second gas distribution element is controlled based on the difference between T1 and T2.

Embodiments described herein provide for heat reclamation and temperature control of a SOFC for a submersible vehicle. The vehicle includes a SOFC, a hot box that surrounds the SOFC, a cooling loop, and a Stirling engine. The cooling loop has a heat exchanger and a coolant pump. The heat exchanger thermally couples the cooling loop to the water. The Stirling engine has a first end thermally coupled to an interior of the hot box and a second end thermally coupled to the cooling loop. The coolant pump modifies a rate of heat removal from the second end of the Stirling engine based on a pump control signal. A thermal management controller monitors a temperature of a cathode outlet of the SOFC, and modifies the pump control signal to maintain the temperature of the cathode outlet within a temperature range.

A fuel cell stack including a plurality of fuel cells, each end of the fuel cell stack having a heater plate disposed between a current collector plate and an end plate, each heater plate being thermally insulated from a respective end plate, wherein each heater plate comprises a heating element in the form of an electrically conductive track; and, wherein the heater plate comprises a pair of terminals extending from an edge of the heater plate, the terminals being separated by an air gap.

Provided is a power conversion system having a solid-oxide fuel cell capable of stably generating electricity from hydrogen generated by an organic hydride. The power conversion system includes a solid-oxide fuel cell, a reactor for producing hydrogen and a dehydrogenation product from an organic hydride by dehydrogenation reaction, and a heat engine for generating motive power. The power conversion system separates the hydrogen produced by the reactor, and supplies the hydrogen as fuel to the solid-oxide fuel cell. Exhaust heat of the heat engine is supplied to both the solid-oxide fuel cell and the reactor.