Abstract: A fuel cell stack includes a heat exchange unit that performs heat exchange between a gas mixture containing source hydrogen and a circulating gas and cooling water used for controlling the temperature of the fuel cell stack. A system controller adjusts the temperature of the cooling water by controlling a temperature control unit on the basis of the temperature of source hydrogen flowing into a junction at which the source hydrogen and a circulating gas are mixed such that the temperature of a source/recirculated hydrogen mixture that is mixed at the junction and that is supplied to the fuel cell stack is kept within a managed temperature range.

Abstract: A fuel cell system includes a controller that estimates or detects an air replacement state of a fuel electrode and a hydrogen circulation path while the operation of the fuel cell system is stopped. Upon starting the fuel cell system, the controller changes the order in which the operation of a hydrogen circulation pump is started and a hydrogen pressure regulator is opened to start the supply of hydrogen gas on the basis of the estimated or detected air replacement state, thereby preventing deterioration caused by uneven distribution of air and hydrogen in the fuel electrode.

Abstract: A fuel cell has an anode, a cathode, and a proton-exchange membrane disposed between the anode and cathode. An exhaust anode gas exhausted from an outlet of the anode is directed back to an inlet of the anode. Hydrogen is added to the exhaust anode gas before the exhaust anode gas reaches the inlet.

Abstract: Moisture caused by humidity in the fuel gas and water vapor from the water that is generated become condensed inside a fuel cell when power generation in the fuel cell is temporarily stopped, making obstruction to the fuel gas flow channel when power generation is restarted possible. A fuel cell includes an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode. Oxidant is supplied to the oxidant electrode in the fuel cell, and the fuel emitted from the fuel electrode of the fuel cell is resupplied back to the fuel electrode. When requested power generating capacity for the fuel cell is less than a prescribed capacity, the oxidant supply is temporarily stopped while the fuel continues to circulate in order to prevent obstruction in the fuel flow channel due to water condensation, making a reliable fuel supply becomes possible.

Abstract: A fuel cell stack (1) performs power generation using an anode gas having hydrogen as its main component, and after a power generation reaction, the anode gas is discharged as anode effluent. The anode effluent is re-circulated into the anode gas through a return passage (5). The return passage (5) comprises a purge valve (8) which discharges the anode effluent to the outside of the passage. In this invention, calculation of a first energy loss caused by an increase in non-hydrogen components in the anode gas while the purge valve (8) is closed (S7, S28), and calculation of a second energy loss which corresponds to the amount of hydrogen lost from the anode gas by opening the purge valve (8) (S8, S29) are performed. By opening the purge valve (8) when the second energy loss equals or falls below the first energy loss, the start timing of purging is optimized.

Abstract: A fuel cell stack includes a heat exchange unit that performs heat exchange between a gas mixture containing source hydrogen and a circulating gas and cooling water used for controlling the temperature of the fuel cell stack. A system controller adjusts the temperature of the cooling water by controlling a temperature control unit on the basis of the temperature of source hydrogen flowing into a junction at which the source hydrogen and a circulating gas are mixed such that the temperature of a source/recirculated hydrogen mixture that is mixed at the junction and that is supplied to the fuel cell stack is kept within a managed temperature range.

Abstract: A fuel cell system includes a controller that estimates or detects an air replacement state of a fuel electrode and a hydrogen circulation path while the operation of the fuel cell system is stopped. Upon starting the fuel cell system, the controller changes the order in which the operation of a hydrogen circulation pump is started and a hydrogen pressure regulator is opened to start the supply of hydrogen gas on the basis of the estimated or detected air replacement state, thereby preventing deterioration caused by uneven distribution of air and hydrogen in the fuel electrode.

Abstract: A system controller drives a gas circulator with a purge valve closed to supply hydrogen to a fuel cell stack and then increases anode operating pressure and cathode operating pressure to target operating pressures after a predetermined condition is satisfied. This allows an amount of gas mixture of remaining oxygen and hydrogen to be suppressed compared to the case of increasing the anode operating pressure in a state where oxygen remains in the anode circulation path. Accordingly, it is possible to suppress local generation of electric potential and heat and prevent degradation of the components of the fuel cell stack. Moreover, hydrogen is not discharged during activation, which eliminates the need to include dilution equipment of combustion equipment for treating hydrogen and increases the degree of freedom in the layout of the fuel cell system.

Abstract: Moisture caused by humidity in the fuel gas and water vapor from the water that is generated become condensed inside of the fuel cell when power generation in the fuel cell is temporarily stopped, making it necessary to prevent obstruction to the fuel gas flow channel when power generation is restarted. A fuel cell is configured so that it overlaps with a single cell comprised of an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode. Oxidant supply means 202 supplies oxidant to the oxidant electrode in the fuel cell. Exhaust fuel circulation means 205 resupplies the fuel emitted from the fuel electrode of the fuel cell back to the fuel electrode.

Abstract: In a fuel cell power plant, carbon monoxide contained in reformate gas which is produced by a reformer (3) by means of a catalytic fuel reaction is removed by the respective catalytic reactions of a shift converter (4) and a preferential oxidation reactor (5). During start up of the fuel cell power plant, a burner (6) burns fuel to produce combustion gas and the combustion gas is supplied individually to the reformer (3), shift converter (4) and preferential oxidation reactor (5) through combustion gas supply passages (71-73) thereby simultaneously completing warming up of these catalytic reactors (3-5).

Abstract: A fuel reforming system generates burnt gas by burning fuel and air in a burner (6) during system startup, and the temperatures of a reforming reactor (7) and carbon monoxide oxidizer (40) are raised by supplying the burnt gas to the reforming reactor (7) and carbon monoxide oxidizer (40). The temperature of the burnt gas produced by the burner (6) is increased according to the elapsed time from the beginning of the startup processing.

Abstract: A fuel cell has an anode, a cathode, and a proton-exchange membrane disposed between the anode and cathode. An exhaust anode gas exhausted from an outlet of the anode is directed back to an inlet of the anode. Hydrogen is added to the exhaust anode gas before the exhaust anode gas reaches the inlet.

Abstract: A fuel cell stack (1) performs power generation using an anode gas having hydrogen as its main component, and after a power generation reaction, the anode gas is discharged as anode effluent. The anode effluent is re-circulated into the anode gas through a return passage (5). The return passage (5) comprises a purge valve (8) which discharges the anode effluent to the outside of the passage. In this invention, calculation of a first energy loss caused by an increase in non-hydrogen components in the anode gas while the purge valve (8) is closed (S7, S28), and calculation of a second energy loss which corresponds to the amount of hydrogen lost from the anode gas by opening the purge valve (8) (S8, S29) are performed. By opening the purge valve (8) when the second energy loss equals or falls below the first energy loss, the start timing of purging is optimized.

Abstract: The fuel cell system according to this invention disposes a moisture exchanger (30) at a suction side of an air supply device (7). This causes an increase in the pressure differential and temperature differential of the fresh air and the cathode exhaust in the moisture exchanger (30) and promotes transfer of moisture. Since the moisture exchanger (30) effectively transfers moisture, it is possible to downsize the radiator for the cooling water and the condenser (60). Thus it is possible to reduce the weight and size of the fuel cell system.

Abstract: A system controller drives a gas circulator with a purge valve closed to supply hydrogen to a fuel cell stack and then increases anode operating pressure and cathode operating pressure to target operating pressures after a predetermined condition is satisfied. This allows an amount of gas mixture of remaining oxygen and hydrogen to be suppressed compared to the case of increasing the anode operating pressure in a state where oxygen remains in the anode circulation path. Accordingly, it is possible to suppress local generation of electric potential and heat and prevent degradation of the components of the fuel cell stack. Moreover, hydrogen is not discharged during activation, which eliminates the need to include dilution equipment of combustion equipment for treating hydrogen and increases the degree of freedom in the layout of the fuel cell system.

Abstract: In a fuel cell power plant, carbon monoxide contained in reformate gas which is produced by a reformer (3) by means of a catalytic fuel reaction is removed by the respective catalytic reactions of a shift converter (4) and a preferential oxidation reactor (5). During start up of the fuel cell power plant, a burner (6) burns fuel to produce combustion gas and the combustion gas is supplied individually to the reformer (3), shift converter (4) and preferential oxidation reactor (5) through combustion gas supply passages (71-73) thereby simultaneously completing warming up of these catalytic reactors (3-5).

Abstract: A fuel cell control system 1 includes a cooling liquid inlet temperature sensor 16 and a cooling liquid outlet temperature for detecting an operating temperature of a fuel cell stack 11A, a radiator 14 by which the operating temperature of the fuel cell stack 11A is regulated, and a control box 19 operative to set a fundamental target operating temperature, which forms an operating temperature to be a target for the fuel cell stack 11A to operate, to either an appropriate operating temperature range on a high temperature side or an appropriate operating temperature range on a low temperature side, which maximizes a system efficiency of the fuel cell system on a high temperature side, to control a bypass rate of the radiator 14 through a three-way valve 15 so as to allow the operating temperature of the fuel cell stack 11A to approach to the fundamental target operating temperature.

Abstract: A fuel reforming system generates burnt gas by burning fuel and air in a burner (6) during system startup, and the temperatures of a reforming reactor (7) and carbon monoxide oxidizer (40) are raised by supplying the burnt gas to the reforming reactor (7) and carbon monoxide oxidizer (40). The temperature of the burnt gas produced by the burner (6) is increased according to the elapsed time from the beginning of the startup processing.

Abstract: A vehicle fuel cell system according to this invention comprises a controller (20) that compares a input running distance to a predetermined distance. When the input running distance is less than the predetermined distance, the controller (20) finishes running using only the hydrogen supplied from a hydrogen storage device (14) without starting a start-up combustor (50). When the input running distance is larger than the predetermined distance, the controller (20) starts hydrogen supply from the hydrogen storage device (14), and simultaneously starts warm-up of a reformer (3) by starting the start-up combustor (50). When warm-up of the reformer (3) is complete, supply of hydrogen from the hydrogen storage device (14) finishes, and hydrogen supply from the reformer (3) starts.

Abstract: The hydrogen permeating to a post-separation side (11B) of the membrane hydrogen separator (11) is supplied to an anode chamber (2A) of a fuel cell stack (2) via a hydrogen supply passage (25). A hydrogen recirculation passage (8) recirculates hydrogen from the anode chamber (2A) to the post-separation side (11B). When the hydrogen partial pressure on the post-separation side (11B) increases, air is introduced into the hydrogen recirculation passage (8) from an intake valve (30). When the hydrogen partial pressure decreases, gas in the hydrogen recirculation passage (8) is discharged from an exhaust valve (60). The rate of hydrogen permeation through the membrane hydrogen separator (11) is thereby maintained to a preferred level.