The present disclosure generally relates to monitoring and controlling emissions produced by a fuel cell or fuel cell stack in a fuel cell engine of a vehicle and/or powertrain.

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.

A fuel cell system is disclosed, which includes an anode recirculation loop comprising a fuel cell stack for generating power, a flowmeter for measuring a fuel flow rate of a fuel provided into the anode recirculation loop, a current measuring device for measuring a current drawn from the fuel cell stack, a recycle ratio measuring device for measuring a recycle ratio in the anode recirculation loop, and a processor for estimating a fuel utilization of the fuel cell stack based on the measured fuel flow rate, the measured current and the measured recycle ratio. Methods for operating the fuel cell system are also disclosed.

A fuel cell system having a fuel cell using a fuel gas containing a combustible gas and an oxidant gas to generate power includes an exhaust gas route for an exhaust gas from the fuel cell to circulate, an air supplier absorbing air within the fuel cell system and supplying the air to the exhaust gas, an air supply route for the air to circulate, a merging part where the exhaust gas and the air merge, a discharge route discharging a mixed gas composed of the merged exhaust gas and the air to the atmosphere, and a combustible gas detector that detects the concentration of a combustible gas in the mixed gas. With respect to flow of the air circulating in the air supply route and the discharge route, from the upstream side, the air supplier, the merging part, and the combustible gas detector are disposed in this order.

A fuel cell hydrogen supply fault diagnosis system is provided. The system includes multiple fuel tanks that store hydrogen therein to supply the hydrogen and a fuel tank valve disposed at each of the fuel tanks and configured to be opened or closed to supply or shut off the hydrogen of the fuel tanks. A pressure sensor measures pressure in a fuel supply line that extends from each of the multiple fuel tanks to be integrally connected to a fuel cell stack. A supply amount estimator then estimates a supply amount of hydrogen supplied to the fuel cell stack and a consumption amount estimator estimates a consumption amount of hydrogen consumed in a reaction in the fuel cell stack or discharged therefrom. A fault detector then detects a hydrogen supply state.

A fuel cell system is disclosed, which includes an anode recirculation loop having a fuel cell stack for generating power, a flowmeter, a current sensor and a processor. The flowmeter is configured for measuring a fuel flow rate provided into the anode recirculation loop. The current sensor is configured for measuring a current drawn from the fuel cell stack. The processor is configured for determining a steam to carbon ratio in the anode recirculation loop based on the measured fuel flow rate and the measured current. The fuel cell system further includes a temperature sensor for measuring a temperature in the anode recirculation loop. The process is configured for determining the steam to carbon ration further based on the measured temperature. A method for operating the fuel cell system and a fuel cell power plant are also disclosed.

A fuel cell system includes a fuel cell, a fuel gas supply line, an oxidizing agent gas supply line, a fuel gas discharge line, and a reformer provided in the fuel gas supply line. A first circulating line circulates the fuel gas from the fuel gas discharge line to an upstream side of the reformer in the fuel gas supply line as a first circulating gas. The circulation device is provided in the fuel gas supply line, and suctions the first circulating gas by using the flow of the fuel gas flowing through the fuel gas supply line as a driving flow. A second circulating line circulates the fuel gas from a downstream side of the circulation device in the fuel gas supply line or the fuel gas discharge line to the upstream side of the circulation device in the fuel gas supply line as a second circulating gas.

Various embodiments of the present application are directed to methods of measuring a mass flow rate of at least one exhaust gas constituent in an exhaust gas of a fuel cell. In one example embodiment, the method includes the steps of measuring a volumetric flow rate of the exhaust gas; using a gas sensor to determine a concentration of the at least one exhaust gas constituent, and calculating the mass flow rate of the exhaust gas constituent using the volumetric flow rate of the exhaust gas and the determine concentration of the at least one exhaust gas constituent.

A hydrogen supply control system for a fuel cell is provided. The system includes a fuel cell stack that generates electricity using supplied hydrogen and air and a recirculation line that supplies hydrogen discharged from an outlet of the fuel cell stack back to an inlet of the fuel cell stack. A purge valve is disposed at an outlet side of the fuel cell stack of the recirculation line and discharges hydrogen in the recirculation line to the outside as the outlet is opened. A recirculation determining processor determines a recirculation state of the recirculation line and a concentration estimator estimates a purge amount for each gas, which is purged by the purge valve, based on the determined recirculation state and estimates a concentration of hydrogen in the recirculation line based on the estimated purge amount for each gas.

An anode gas purge control method for a proton exchange membrane fuel cell is disclosed. An anode water management structure is constructed, and an anode nitrogen concentration observer is used to control the anode water management structure to operate. Liquid water contained in gas of a fuel cell stack is taken out by controlling a hydrogen flow rate through a hydrogen circulating pump and removed through a second water-vapor separator. Liquid water precipitated by gas condensation is removed through a first water-vapor separator. A nitrogen concentration observed value is obtained by using the anode nitrogen concentration observer, a purge duration is obtained by using a purge continuation process model, and when the nitrogen concentration observed value reaches a nitrogen concentration threshold, the purge valve is opened and nitrogen is discharged. After the purge duration, the purge valve is closed, and next cycle is entered.