Oxygen Flow Control in Fuel Cell Systems

Fuel cell system with improved efficiency, life, and reliability through multi-aspect control of gas flow, pressure, and humidity. The fuel cell system has separate control subsystems for humidity, flow, and pressure. The humidity control system adjusts gas humidity entering the fuel cell stack. The flow control system regulates gas flow into the stack. The pressure control system manages gas pressure entering the stack. By optimizing these factors, it improves fuel cell efficiency, extends stack life, and reduces costs while maintaining normal operation.

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Power supply system with a fuel cell that provides stable power output in low load conditions to prevent catalyst deterioration and improve durability. In low load states, the fuel cell is operated at reduced power levels by supplying less oxygen compared to normal load conditions. This prevents excessive cell voltages and fluctuation that can elute catalyst. The reduced oxygen level is set to a target voltage that balances cell voltage and catalyst stability. The low power mode is intermittently selected in low load states to avoid prolonged hydrogen consumption. This reduces fuel cell maintenance.

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Fuel cell system to stabilize power generation when air supply is low. The system has a fuel cell stack, air compressor, and ventilation section. It detects oxygen concentration inside the fuel cell unit. When oxygen stoichiometric value (ratio of oxygen consumed to theoretical value) is less than target, it increases airflow or ventilates to raise oxygen. This prevents voltage drop due to low oxygen concentration in supplied air.

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Fuel cell system that can adjust oxygen supply to prevent cell stack overvoltage and degradation when using multiple stacked fuel cells in series. The system has a common air supply pipe connecting the stacks. An air volume controller adjusts the oxygen flow rate based on the output currents of the individual stacks. This compensates for current mismatches between stacks and prevents air shortage in overcurrent stacks. The controller switches between a mode where oxygen supply is proportional to stack currents vs a mode where it's based on individual stack currents, depending on conditions.

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Fuel cell power generation system and control method that prevents overloading of fuel cells and reduces safety risks. The system uses waste heat recovery, air and fuel recirculation, and load matching to optimize cell operation. A control unit adjusts fuel, air, and recycled gas flows based on cell current, temperature, and power demand to maintain optimal cell conditions. This prevents overcurrent by balancing heat and mass transfer. The waste heat recovery system recovers exhaust heat using two-stage heat exchangers and recirculates air and fuel gases. This improves efficiency and reduces the need for external cooling.

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Modifying the anode flow field in a fuel cell to increase efficiency by improving water management. The anode flow field has two configurations, one with a hydrophilic gas diffusion layer and one with a hydrophobic diffusion layer. Hydrogen flows through both configurations. The hydrophilic layer promotes water recycling to reduce flooding compared to the hydrophobic layer. This enhances efficiency by decreasing water accumulation and parasitic loads. It allows humidifying hydrogen and air without additional components.

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Operating a fuel cell system with multiple fuel cell stacks and a shared air supply to improve efficiency and reduce cost compared to separate air systems for each stack. The method involves balancing oxygen supply to the stacks based on their operating conditions. This allows using a single air compression system instead of duplicating it for each stack. The oxygen demand of the stacks is dynamically adjusted by varying the air mass flow and pressure to maintain optimal conditions for each stack. This avoids over-supplying some stacks and under-supplying others, which can lead to inefficiencies and degradation.

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Fuel cell module design with staged fuel supply that improves uniformity of temperature and current density across the fuel cell stack. The design involves strategically placing fuel orifices in the fuel flow shaping plate that connects to the anode channels. This directs fuel from the cold entrance region to the hot middle region where endothermic reforming occurs. It cools the hot spots while staging the fuel supply to distribute reforming reactions throughout the cell. This prevents hotspots and non-uniform current density while maintaining overall efficiency.

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A flow channel design for fuel cells and electrolyzers with vertical channels that improves fluid distribution and reduces mass transfer resistance. The design involves adding vertical channels perpendicular to the main flow channels that circulate fluid. This allows more uniform distribution of reactants like oxygen and water throughout the cell or electrolyzer, preventing localized concentration gradients and improving performance. The vertical channels can be located at the ridges of the main channels.

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Fuel cell system for vehicles that allows faster response times during acceleration. The fuel cell system has a ventilation system to control air flow and stoichiometry. In dynamic mode during acceleration, the ventilation system provides higher air pressure and increased cathode stoichiometry compared to steady-state operation. This allows faster current density changes for acceleration.

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Managing fuel cell voltage during low load or no load conditions to extend cell life. The method involves reducing the oxidant flow rate below the normal operating level when the load is low. This prevents over-oxygenation of the cell which can degrade performance. A valve controls the oxidant flow and positions are adjusted based on load. The valve positions are also coordinated with a compressor bypass valve to prevent pressure spikes. This allows optimized oxidant supply during load variations.

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A fuel cell stack design to improve uniformity of electrical output across cells. The stack has a unique layout with manifolds and channels to optimize reactant flow. The stack has multiple unit fuel cells sandwiched between cover and feeding plates. Each cell has reactant inlet and outlet manifolds. The feeding plate has channels to connect the manifolds to reactant supply and reservoir. The design includes features like turbulence elements, dimensioned channels, and manifold shapes to enhance flow turbulence and prevent short circuits. This improves reactant distribution between cells and mitigates issues like uneven voltage output from end cells.

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Fuel cell system with multiple stack groups that enables adjusting the current output of each stack group independently to prevent voltage imbalances and improve system efficiency when connecting multiple fuel cell stacks in series. The system uses separate power converters for each stack group to control the generated power based on the output current. This allows adjusting the supply of oxygen, hydrogen, and cooling water to match the current requirements of each stack group.

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A method to improve operation stability of fuel cell engines during idling by adjusting the oxygen concentration supplied to the fuel cell stack. The method involves obtaining the engine output power and fuel cell voltage, then regulating the oxygen concentration input to the fuel cell based on that data. This improves consistency of the fuel cell stack cells during idling, addressing the issue of poor performance and voltage variance due to oxygen concentration.

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A fuel cell design with forced flow of reactant gas through the catalytic layers to improve performance and reduce thickness compared to conventional fuel cells. The design eliminates the need for gas diffusion layers and has interdigitated channels on the bipolar plates to forcefully circulate the reactant gas laterally through the catalytic layers. This increases flow rate and reaction speed compared to radial flow. The channels on the plates directly contact the catalytic layers to enable the forced flow without additional layers. The design simplifies the structure, reduces thickness, and improves efficiency by accelerating reactant flow through the catalysts.

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Direct liquid fuel cell with a novel anode flow field to address mass transfer issues caused by bubbles forming during high current density operation. The cell has a flow field plate with interdigitated channels for the anode electrolyte. This design promotes bubble disengagement and prevents bubble accumulation that would otherwise impede mass transfer and stability. The hydrophobic conductive fibers of the flow field plate are arranged in an interdigitated pattern with overlapping inlet and outlet channels. This allows bubbles to detach and escape the anode flow channels as the liquid flows. The flow field plate is attached to the anode diffusion layer.

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Fuel cell system that can flexibly adjust oxygen concentration to improve durability and reliability of the fuel cell stack while efficiently utilizing oxygen resources. The system recycles high concentration oxygen from the stack exhaust and mixes it with air to adjust the oxygen concentration entering the stack. An ejector cools the recycled oxygen to a low temperature. Compressed air is mixed with the cooled oxygen and supplied to the stack. Valves and compressor speed control the oxygen concentration. This prevents stack damage from high oxygen levels while utilizing the recycled oxygen.

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High efficiency solid oxide fuel cell system that recycles the anode exhaust gases to extract hydrogen fuel while also oxidizing the remaining gases. The system includes pumps that extract hydrogen from the anode exhaust in stages, providing the extracted hydrogen back to the fuel cell stack and oxidizing the remaining exhaust gases. This allows purification of the hydrogen fuel and recovery of unspent fuel from the exhaust, improving system efficiency.

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Bipolar flow plate design for fuel cells that improves stack life by preventing reverse flow of catalyst-corrosive gases. The design has two sets of flow channels on the plate, one for forward flow and another for reversible flow. The forward channels allow full flow area, while the reversible channels prevent reverse flow of gases like hydrogen that corrode the electrode catalyst. This prevents catalyst loss and stack degradation in low power conditions where reverse flow occurs. A control method is also provided to switch flow direction based on power level.

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Fuel cell system control method for improved safety, reliability, simplicity, weight reduction, and space reduction of fuel cell systems. The control involves steps like supplying hydrogen before gas containing oxygen, discharging oxygen gas when voltage reaches a reference level, and circulating oxygen gas to avoid carbon corrosion. This prevents dangerous radical reactions and potential fuel cell breakdown. The method also depressurizes the system at startup, monitors impedance, and increases current density gradually.

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