A propulsion system including: a fuel cell assembly having a fuel cell defining an outlet positioned to remove output products from the fuel cell and a fuel cell assembly operating condition; a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the combustion section configured to receive a flow of aviation fuel from an aircraft fuel supply and further configured to receive the output products from the fuel cell; and a controller comprising memory and one or more processors, the memory storing instructions that when executed by the one or more processors cause the propulsion system to perform operations including receiving data indicative of a mid-flight flameout within the combustion section; modifying the fuel cell assembly operating condition in response to receiving data indicative of the mid-flight flameout within the combustion section; and initiating a relight of the combustion section.

A cooling system is provided for use with a fuel cell. The cooling system comprises a first heat exchanger fluidly connected to an outlet passage of the fuel cell. The first heat exchanger can be configured to condense at least a portion of a fluid passing through the outlet passage of the fuel cell into liquid water. The cooling system can also comprise a second heat exchanger fluidly connected to an outlet passage of the first heat exchanger and an inlet passage of the fuel cell. The second heat exchanger can be configured to cool a fluid passing into the inlet passage of the fuel cell. In addition, the outlet passage of the fuel cell and the inlet passage of the fuel cell can be fluidly connected to a cathode of the fuel cell, and the inlet passage of the fuel cell can be configured to supply water to the cathode.

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 vehicle includes a fuel cell system with a fuel cell arrangement and a fuel cell exhaust gas system receiving fuel cell exhaust gas from the fuel cell arrangement. The fuel cell exhaust gas system has a fuel cell exhaust gas outlet region for discharging fuel cell exhaust gas from the fuel cell exhaust gas system, and an ambient air heating arrangement for heating ambient air to be mixed with at least part of the fuel cell exhaust gas. The ambient air heating arrangement has an ambient air outlet region for discharging ambient air heated in the ambient air heating arrangement. The fuel cell exhaust gas outlet region is positioned downstream of the ambient air outlet region with respect to an ambient air flow direction of the heated ambient air discharged from the ambient air heating arrangement at the ambient air outlet region.

Systems and methods are provided for operating molten carbonate fuel cells to produce increased amounts of H.sub.2 in the anode effluent while still maintaining operation of the cell within conventional operation boundaries, such as having a temperature differential between the cathode input flow and the cathode effluent of 35 C. or more, with the cathode effluent being hotter than the cathode input flow. This temperature differential between the cathode input flow and the cathode effluent while still producing excess hydrogen is achieved in part by a) passing an input flow containing hydrocarbons and/or reformable fuel into an external reformer, b) reforming 20 vol % or more of the hydrocarbons and/or reformable fuel in the external reformer prior to c) passing the partially reformed input flow into a fuel cell or fuel cell stack where additional reforming is performed in the anode(s) and/or in a reforming element in the fuel cell stack.

Electrochemical systems providing reversible operation of high specific energy or gravimetric energy, and high energy density or volumetric energy battery chemistries, methods of operating such systems, processes providing high energy densities and high power densities, and architectures for the successful implementation of such systems, methods and processes. A number of interconnected electrochemical reactors can be assembled to create a battery. By presenting fluidic reactants via pumping, injection and/or other circulation technologies that enable high specific energy, high utilization of reactants, and efficient thermal control, the operation of the electrochemical reactor/battery can be optimized. In a flow battery system and method for handling molten alkali metal and hydroxide species, the volume of the reactants is maximized over inactive components and thus increase energy density. Molten and gaseous reactants/products are fed to/removed from a central power conversion module from/fed to reservoirs for discharge/charge.

A fuel cell system includes: a reformer which generates a reformed gas containing hydrogen by reacting hydrocarbon and moisture with each other; a fuel cell stack which generates electric energy through electrochemical reaction of the reformed gas and an oxidant; an ejector which, using steam as a drive fluid, sucks either a raw fuel containing the hydrocarbon or a recycled gas recovered from an anode exhaust gas, and supplies a resultant gas to the reformer; and a vaporizer which generates the steam by vaporizing water, wherein an operation temperature of the fuel cell stack is higher than a boiling point of water at an operation pressure, and the vaporizer generates the steam through heat exchange with the anode exhaust gas.

Disclosed is a hydrogen feed conditioning system for a hydrogen fuel cell in which fresh hydrogen from storage and recycled hydrogen from an anode exhaust of the fuel cell are mixed and fed to an anode feed of the fuel cell. A stream of recycled hydrogen is first passed through a hydrogen/water separator configured to reduce an amount of water vapor in the recycled hydrogen stream. The system includes a condenser for the anode exhaust stream upstream of the hydrogen water separator.

The invention relates to a method for humidifying air in a supply air path (2) of a fuel cell system (1) by means of water injection, wherein product water produced on the cathode side is used, with said product water being separated from the humid exhaust air introduced into the exhaust air path (3) with the aid of a water separator (4) integrated into the exhaust air path (3), wherein, depending on the load, the liquid water content of the exhaust air is varied by means of the temperature of the exhaust air.

The invention also relates to a device for humidifying air in a supply air path (2) of a fuel cell system (1) and to a fuel cell system (1) comprising a device according to the invention.

A fuel cell system including a fuel cell, an off-gas reprocessing unit that is provided downstream of the fuel cell and that at least partially removes at least one of steam or carbon dioxide from an off-gas discharged from the fuel cell, a flow passage that is provided downstream of the off-gas reprocessing unit and that allows a reprocessed off-gas discharged from the off-gas reprocessing unit to flow therethrough, and a controlling unit that modulates the reaction constant K.sub.pa of a reaction A with respect to the reprocessed off-gas discharged from the off-gas reprocessing unit, to 1.22 or more.