The present disclosure generally relates to systems and methods for using a relative humidity sensor in a cathode exhaust stream of a fuel cell stack to optimize the performance and efficiency of the fuel cell stack.

An energy storage system includes a vanadium redox battery that interfaces with a control system to optimize performance and efficiency. The control system calculates optimal pump speeds, electrolyte temperature ranges, and charge and discharge rates. The control system instructs the vanadium redox battery to operate in accordance with the prescribed parameters. The control system further calculates optimal temperature ranges and charge and discharge rates for the vanadium redox battery.

A reforming element for a molten carbonate fuel cell stack and corresponding methods are provided that can reduce or minimize temperature differences within the fuel cell stack when operating the fuel cell stack with enhanced CO.sub.2 utilization. The reforming element can include at least one surface with a reforming catalyst deposited on the surface. A difference between the minimum and maximum reforming catalyst density and/or activity on a first portion of the at least one surface can be 20% to 75%, with the highest catalyst densities and/or activities being in proximity to the side of the fuel cell stack corresponding to at least one of the anode inlet and the cathode inlet.

The present disclosure generally relates to systems and methods in a vehicle or powertrain system including an air stream flowing through an air compressor and an air cooler into a fuel cell stack, an air stream flowing out of the fuel cell stack to an ambient through a backpressure valve, one or more sensors for measuring pressure or temperature in the first air stream or second air stream, and a controller controlling the flow of the first air stream, the flow of the scond air stream and the opening of the backpressure valve.

In order to protect the temperature of an exhaust stream in an exhaust line, even if the temperature of the exhaust stream discharged from a fuel cell exceeds a temperature during rated operation, a power generation system has: an SOFC; an exhaust air line or an exhaust fuel line, wherein the exhaust air line and exhaust fuel line carry exhaust air and exhaust fuel gas discharged from the SOFC, respectively; a temperature detector for detecting the temperature of the exhaust air or the exhaust fuel gas discharged from the SOFC or the temperature of the exhaust air line or the exhaust fuel line; an exhaust cooling device for cooling the exhaust air in the exhaust air line or the exhaust fuel gas in the exhaust fuel line; and a control device for activating the exhaust cooling device when the temperature detected by the temperature detector exceeds a predetermined temperature.

The invention relates to a fuel cell system comprising a stack of electrochemical cells forming a polymer ion-exchange membrane fuel cell (6), a fuel gas supply circuit and an oxidant gas supply circuit.

Said oxidant gas supply circuit comprises a compressor (3) intended to compress the ambient air before it enters the fuel cell (6), and an outlet exhaust (10) intended to discharge the gases leaving the fuel cell.

Said supply circuit is connected to the fuel cell at a first access point (7) and a second access point (8).

The system additionally comprises a switching element (11) that has two positions: a first position in which the outlet of the compressor (3) is connected to the first access point (7), and the second access point (8) is connected to the outlet exhaust (10), and a second position in which the outlet of the compressor (3) is connected to the second access point (8), and the first access point (7) is connected to the outlet exhaust (10).

The system is characterized in that it contains a moisture reservoir positioned in the oxidant gas supply circuit, upstream of the first access point (7).

An assembly including a fuel cell arranged in a housing, the fuel cell includes an anode having an admission and an anode discharge, and a cathode having an oxygen admission and a cathode discharge, the assembly includes the housing and a sealed enclosure in which the fuel cell is arranged and configured in such a manner that the gas discharged by the fuel cell is discharged into the sealed enclosure so as to generate an over-pressure of oxygen-depleted air inside the sealed enclosure.

A method for supplying air to a fuel cell (2), using a controllable air conveying device (7) which delivers an air mass flow for a cathode chamber (4) of the fuel cell (2), and using at least one air mass flow sensor (9, 18). The invention is characterized in that, for at least one location (19) in the air flow path which is situated at a distance from the at least one air mass flow sensor (9) in the flow direction, a computed estimate is made of the air mass flow present at that location.

A method of shutting down operation of a fuel cell system is disclosed, comprising a fuel cell stack, the method comprising the sequential steps of: i) ceasing a supply of fuel to the fuel cell stack; ii) closing a shut-off valve on an exhaust line in fluid communication with a cathode system of the fuel cell system, the cathode system comprising a cathode fluid flow path passing through the fuel cell stack; iii) pressurizing the cathode system with an air compressor in fluid communication with a cathode air inlet port in the fuel cell stack; and iv) ejecting water from the cathode flow path.

A fuel cell system includes fuel cell stacks, each of which includes a plurality of fuel cells that are connected in series and generate electricity through an electrochemical reaction between a fuel gas and an oxidant gas, fuel cell cartridges, each of which has headers that supplies the fuel gas and the oxidant gas to the fuel cell stacks and discharges a fuel off-gas and an oxidant off-gas from the fuel cell stacks, a fuel gas supply line that supplies the fuel gas to the fuel cell cartridges, a fuel off-gas discharge line that discharges the fuel off-gas from the fuel cell cartridges, and a first adjustment member provided in the fuel gas supply line or the fuel off-gas discharge line, and adjusting a flow rate of the fuel gas or the fuel off-gas, the first adjustment member including a first flexible pipe.