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 fuel cell stack has a plurality of fuel cells arranged in a row, each of them comprising a membrane separating the electrodes, with ports for the respective supply and drainage of a fuel and an oxidizer and with a tensioning device for pressing the fuel cells together, wherein the tensioning device is formed by a band and spring system having an integrated force transducer, the signal of which can be relayed to a controller for determining the moisture content based on the moisture-dependent swelling behavior of the membrane of each fuel cell. A fuel cell device with such a fuel cell stack as well as a motor vehicle having such a fuel cell device are also provided.

A fuel cell stack has a plurality of fuel cells arranged in a row, each of them comprising a membrane separating the electrodes, with ports for the respective supply and drainage of a fuel and an oxidizer and with a tensioning device for pressing the fuel cells together, wherein the tensioning device is formed by a band and spring system having an integrated force transducer, the signal of which can be relayed to a controller for determining the moisture content based on the moisture-dependent swelling behavior of the membrane of each fuel cell. A fuel cell device with such a fuel cell stack as well as a motor vehicle having such a fuel cell device are also provided.

A fuel cell system mounted on a vehicle includes a fuel cell, a humidity sensor configured to detect a humidity in a vehicle cabin of the vehicle, a cathode off-gas exhaust passage through which cathode off-gas emitted from the fuel cell is exhausted to outside the vehicle, an introducing port for cathode off-gas, provided in the cathode off-gas exhaust passage, a cathode off-gas introducing unit configured to introduce cathode off-gas emitted from the fuel cell, into the vehicle cabin of the vehicle via the introducing port, and a cathode off-gas introducing amount control unit configured to control an amount of the cathode off-gas introduced into the vehicle cabin of the vehicle in accordance with a humidity in the vehicle cabin of the vehicle, detected by the humidity sensor.

A fuel cell system that generates electric power by supplying anode gas and cathode gas to a fuel cell includes a control valve adapted to control the pressure of the anode gas to be supplied to the fuel cell; a buffer unit adapted to store the anode-off gas to be discharged from the fuel cell; a pulsation operation unit adapted to control the control valve in order to periodically increase and decrease the pressure of the anode gas at a specific width of the pulsation; and a pulsation width correcting unit adapted to correct the width of the pulsation on the basis of the temperature of the buffer unit.

A fuel cell system includes a membrane electrode assembly, an anode-side internal passage, a cathode-side internal passage, an oxygen supply section, and a control device. The oxygen supply section includes a gas circulation passage connected to one end side and the other end side of the cathode-side internal passage, an oxygen supply source connected to the gas circulation passage, and a gas circulation device configured to circulate and flow oxygen gas in any one of one direction and the other direction in the gas circulation passage. The control device switches a flow direction of the oxygen gas by the gas circulation device according to a distribution state of moisture on the cathode electrode of the membrane electrode assembly.

A method for diagnosing at least one fuel cell stack of a fuel cell device by way of a fuel cell diagnostic system includes: impressing a sinusoidal first and at least one sinusoidal second AC current into the fuel cell stack; recording a sinusoidal first and second voltage response of the fuel cell stack; evaluating the first voltage response and evaluating the second voltage response by way of an analytical algorithm for a differential impedance analysis; determining a first resistance, a second resistance and a capacitance of the fuel cell stack by specifying an equivalent circuit diagram for the fuel cell stack; and diagnosing the fuel cell stack on the basis of the determined first resistance, the determined second resistance and the determined capacitance, wherein the diagnosis is carried out in real time. A computer-readable storage medium and a fuel cell diagnostic system are also described.

A fuel cell system and a method for controlling the same may adjust generation of condensate water in a fuel cell by setting relative humidities and temperature and pressure conditions of the fuel cell so as to maintain a constant current density, and may alleviate performance deterioration of the fuel cell during operation by removing an excessive amount of the generated condensate water by injecting a cathode pressure impulse into the fuel cell.

A fuel cell system and a method for controlling the same may adjust generation of condensate water in a fuel cell by setting relative humidities and temperature and pressure conditions of the fuel cell so as to maintain a constant current density, and may alleviate performance deterioration of the fuel cell during operation by removing an excessive amount of the generated condensate water by injecting a cathode pressure impulse into the fuel cell.

A method for distinguishing the cause of voltage losses in a fuel cell device includes: a) Detection of a quasi-stationary operation of the fuel cell device, b) Acquisition and storage of a measured current-voltage characteristic curve with the current values and the voltage values of a fuel cells stack of the fuel cell device, c) Use of a PtOx model to determine PtOx voltage losses and calculation of a corrected current-voltage characteristic curve for the PtOx-free and normally humidified fuel cell stack, and d) Comparison of the current-voltage characteristic curves determined in step b) and in step c) and detection of an at least partially dried-out fuel cell stack if the measured current-voltage characteristic curve runs below the corrected current-voltage characteristic curve. A fuel cell device and a motor vehicle comprising a fuel cell device are also provided.