A vehicle power system including a fuel cell auxiliary power unit for providing clean, efficient power to a vehicle. The system generally includes a fuel cell with a first DC output and a heat output, a pressure vessel adapted to contain and provide pressurized hydrogen to the fuel cell, an electrical storage unit with a DC input coupled to the first DC output of the fuel cell. The electrical storage unit also has a second DC output. An inverter is coupled to the second DC output of the electrical storage unit to receive power, the inverter having a first AC output. The system can provide heat, AC power, and DC power to the vehicle.

A method for simulating a phenomenon involving phase change includes: calculating, by a processor, a degree of phase change in a porous medium per unit volume and unit time based on an area of a gas-liquid interface in the porous medium per unit volume and a phase change rate at the gas-liquid interface.

A redox flow battery system includes an anolyte having chromium ions in solution, wherein at least a portion of the chromium ions form a chromium complex with at least one of the following: NH.sub.3, NH.sub.4.sup.+, CO(NH.sub.2).sub.2, SCN.sup.−, or CS(NH.sub.2).sub.2; a catholyte having iron ions in solution; a first half-cell including a first electrode in contact with the anolyte; a second half-cell including a second electrode in contact with the catholyte; and a first separator separating the first half-cell from the second half-cell.

A method for determining an average oxidation state (AOS) of a redox flow battery system includes measuring a charge capacity for a low potential charging period starting from a discharged state of the redox flow battery system to a turning point of a charge voltage; and determining the AOS using the measured charge capacity and volumes of anolyte and catholyte of the redox flow battery system. Other methods can be used to determine the AOS for a redox flow battery system or use discharge voltage instead of charging voltage.

To provide a fuel-efficient fuel cell system configured to eliminate flooding in a fuel-based gas flow path, etc. The fuel cell system is a fuel cell system comprising a first fuel cell stack, a second fuel cell stack, a fuel gas supplier, a first supply flow path, a first circulation flow path, a second supply flow path, a second circulation flow path, a first bypass flow path which includes a first on-off valve, a second bypass flow path which includes a second on-off valve, a temperature detector, a current detector, a voltage detector and a controller.

Methods and apparatus for detecting electrical short circuits in fuel cell stacks are provided. The methods involve supplying a reactant and an inert gas to a fuel cell stack and measuring the open circuit voltage of fuel cell assemblies in the fuel cell stack. The sensitivity of the methods can be adjusted to detect an electrical short circuit having a resistance at or below a particular threshold short-circuit resistance value, by using a suitable reactant concentration in the method. The methods can include determining a set-point reactant concentration that can be used to detect an electrical short circuit having a resistance at or below a particular threshold short-circuit resistance value.

A supply device for supplying electricity to at least one consumer includes: a primary power supply in which there is a first fuel cell device having a first performance; a voltage transformer which connects the primary power supply to a secondary power supply having a battery; and a measuring device for detecting an insulation resistance of the primary power supply and/or of the secondary power supply. A second fuel cell device having a second performance is connected in series with the first fuel cell device in the primary power supply, wherein a bridge circuit comprising a switch is connected in parallel with each of the fuel cell devices and wherein the switches of the bridge circuits can be switched in accordance with the detected insulation resistance. A fuel cell vehicle and a method for limiting voltage in a supply device are also provided.

A system and method for controlling operation of a fuel cell system are described. The method includes diagnosing fuel cells by collecting voltage information of the fuel cells and selecting fuel cells vulnerable to reverse voltage based on the collected voltage information of the fuel cells, classifying the selected fuel cells vulnerable to reverse voltage depending on predetermined vulnerable operating conditions by confirming operating conditions of the selected fuel cells vulnerable to reverse voltage, and performing compensatory operation of the fuel cell system by executing fuel compensation control of the fuel cells vulnerable to reverse voltage depending on the classified vulnerable operation conditions.

A fuel cell system for air vehicles, wherein the fuel cell system comprises: a fuel cell, a fuel gas system for supplying fuel gas to the fuel cell, a potential sensor, and a controller; wherein the fuel gas system comprises a fuel gas supplier; wherein the controller determines whether or not a potential of the fuel cell measured by the potential sensor, is a reversal potential; and wherein, when the controller determines that the potential of the fuel cell is a reversal potential, the controller increases a fuel gas supply from the fuel gas supplier to the fuel cell.

A fuel cell system includes a fuel cell stack and a control device. The control device raises the voltage of the fuel cell stack until a predetermined voltage condition is met, by supplying a cathode with an oxidant gas before current sweep is started when the fuel cell system is started and a value measured by a temperature sensor is equal to or less than a temperature determined in advance. The control device executes stand-by control, in which a current command value is kept constant, when a measured voltage value reaches a control start voltage value smaller than a voltage command value in a transition period, and ends the stand-by control by permitting a change in the current command value when the measured voltage value reaches a permission voltage value equal to or more than the voltage command value during execution of the stand-by control.