Hydrogen Flow Optimization in Fuel Cells

Pulse hydrogen supply system for a proton exchange membrane fuel cell that can provide a pulsating hydrogen flow to remove water droplets from the fuel cell. The system has two vessels, one high-pressure and the other low-pressure, which can generate pressure waves through opening and closing of electromagnetic valves. This pulsating hydrogen flow helps dynamically dislodge and remove water droplets that can accumulate in the fuel cell, ensuring proper humidification of the membrane, thus improving cell performance and durability.

Source

A recirculation system for purging and recirculating hydrogen in a fuel cell stack, which avoids the need for external compressors and enables recovery of purged hydrogen. The system uses a tank with outlet connected to the fuel cell and an inlet to receive purged water and hydrogen. A one-way valve allows flow from the fuel cell to the tank during normal operation when pressure is high. When pressure drops due to hydrogen consumption, the valve opens to allow recirculation back to the fuel cell. This recirculates purged hydrogen without external compression.

Source

A fuel cell system for vehicles like tractors and backhoes that adjusts the temperature inside the hydrogen tank based on the amount of hydrogen remaining. When the hydrogen level gets low, the system increases the tank temperature to release more available gas. This allows quick response to load changes without reducing fuel cell output. It also reduces unused hydrogen left in the tank.

Source

Automated switching between multiple hydrogen fuel tanks on a mobile power generator to provide continuous power and avoid interruptions. A pressure-based latching switch monitors the fuel tank pressures, and automatically switches from an empty tank to a full tank to maintain a constant fuel supply to the generator's fuel cell system.

Source

Preventing accidental closing of fuel cell hydrogen injectors when starting power-hungry vehicle auxiliaries. A fuel cell vehicle has a hydrogen injector that opens when a current threshold is reached. The injector controller increases the current target when it detects start signals from high-power auxiliaries like AC. This prevents power dips from closing the injector prematurely. However, if a voltage converter supplies the injector, the target is not increased if converter output exceeds the main power supply.

Source

Process and system to mitigate overpressure in fuel cell anodes to prevent damage in the event of injector failure by detecting a stuck open injector and closing the hydrogen valve to prevent excess supply. The fuel cell stack continues to run and consume hydrogen to deplete the anode pressure. Other actions include opening the anode bleed valve, increasing cathode air pressure, and modulating load to maintain pressure balance.

Source

Method to maintain constant hydrogen partial pressure in a fuel cell stack during purging cycles. It involves measuring hydrogen concentration at the stack outlet and updating the target hydrogen supply pressure based on the nitrogen crossover pressure increase between purges. This compensates for nitrogen dilution during purging to prevent hydrogen pressure drops. The target pressure is calculated by summing the normal hydrogen pressure needs with the crossover nitrogen pressure.

Source

Minimizing fuel cell stack degradation and efficiently satisfying the required output of the stack by employing an air recirculation valve and a hydrogen recirculation pump. The fuel cell system has separate air and hydrogen supply lines. It recirculates some of the air and hydrogen from the cathode and anode back into the stack. The recirculation flow rates are controlled based on stack output voltage and current. This helps balance cell pressures and prevent voltage/current imbalances that cause stack degradation when output is low.

Source

A fuel cell flushing system and method to remove nitrogen from the fuel cell stack without restarting the fuel cell. The system uses the fuel supply valve and hydrogen line purge valve to change hydrogen flow velocity. First, adjust hydrogen pressure in the supply line. Then, open supply valve and cut off purge valve to increase flow. This flushes nitrogen from the cell without restarting.

Source

Hydrogen fuel cell system with improved performance and reliability through pulsed jet recirculation and pulse width modulated (PWM) injectors. The system reduces hydrogen pressure from high to medium using pulsed injectors instead of mechanical pressure reducers. This provides better control, stability, and controllability. The pulsed injectors have discrete open and closed states. PWM control allows adjusting recirculation rate by pulse width. This pulsed recirculation improves efficiency and stability compared to continuous recirculation. The pulsed injectors also have lower stress and longer life than continuous valves.

Source

Improving hydrogen utilization in fuel cell systems by decoupling the pressure and hydrogen flow control of the anode purge valves. The method involves determining compensation values for adjusting the proportional valve opening and tail exhaust valve closing to compensate for the influence of one variable on the other. By using these compensated values instead of the original openings, stable anode pressure can be achieved while mitigating hydrogen waste during purge cycles. This allows single variable control of both pressure and utilization instead of the coupled multi-variable control.

Source

Fuel cell hydrogen circulation system and control method that improves hydrogen utilization and efficiency at both low and high power levels. The system has parallel loops with a hydrogen circulation pump for low power and an ejector for high power. Switch valves allow selecting the pump or ejector based on fuel cell output. At low power, the pump recirculates hydrogen. At high power, the ejector injects hydrogen into the cell outlet for reuse. This avoids pumping energy waste while still providing sufficient hydrogen flow for high power.

Source

Fuel cell nitrogen purging system and control method to improve fuel cell startup performance by optimizing nitrogen purging after shutdown. The system uses a hydrogen recirculation loop and a variable bypass flow to purge nitrogen from the hydrogen storage tank. A sensor measures the recirculated hydrogen concentration. The bypass flow is increased if the hydrogen concentration is too low, allowing faster purging. If the concentration is too high, the bypass flow is decreased to save power. This adaptive purge strategy prevents excessive hydrogen waste and concentration extremes.

Source

Method for supplying an anode of a fuel cell stack through an anode supply of a fuel cell unit that enables expanding the operating range of the fuel cell stack at low loads. The method involves operating at least one hydrogen metering valve in the anode supply path in a pulsed (clocked) manner in a specific operating range of the fuel cell stack. This allows supplying the anode with hydrogen in a pulsed manner at low loads instead of continuously. It prevents excessive differential pressures in the anode at high loads while enabling operation at lower loads where continuous supply is not required.

Source

Hydrogen supply system for fuel cell vehicles that provides precise hydrogen flow control to enable stable fuel cell performance under varying load conditions. The system has a primary hydrogen supply branch with fixed flow rate and a secondary branch with adjustable flow. A valve controls the secondary branch flow. By using both branches, hydrogen supply can be tailored to meet demand. This prevents under/over supply issues with a fixed branch when load changes. The secondary branch also allows increasing hydrogen flow for high power loads. A feedback flow meter adjusts the valve for precise hydrogen flow.

Source

Fuel cell stack anode water management and control system that prevents flooding and drying issues in fuel cells to improve performance and reliability. The system uses solenoid valves to selectively open and close the anode hydrogen inlet and outlet ports. This allows controlling the hydrogen flow direction and volume to balance water distribution inside the stack. By monitoring stack internal resistance, the valves are automatically switched to prevent flooding and drying.

Source

Fuel cell system with selective hydrogen discharge to improve stability and durability. The system has two hydrogen discharge lines from the fuel cell stack: one connects to the air discharge line upstream of the pressure adjuster, the other connects to the air discharge line downstream. A valve on each line opens/closes based on anode pressure. This allows flexible hydrogen discharge without pressure fluctuations. It prevents corrosion from cathode hydrogen and stabilizes output vs. discharge flowrate.

Source

A fuel cell hydrogen supply system that enables reliable operation of fuel cell systems in applications like power generation. The system has a dedicated hydrogen supply unit connected to the fuel cell stack. It uses a control strategy with separate basic and feedback compensation duty settings for the hydrogen supply valve. The basic duty is set based on stack status, and feedback compensation adjusts based on stack performance. This allows optimized hydrogen supply to prevent stack voltage imbalances and durability issues.

Source

Hydrogen common rail control system for fuel cells that improves hydrogen flow accuracy and reduces heat generation in fuel cells by using an ejector and pump in parallel, closed-loop control of proportional valves, and a switch valve. The system has two proportional valves, one main valve and one bypass valve, that are controlled based on pressure feedback to ensure consistent outlet pressures. This reduces variations in hydrogen flow due to valve consistency issues. An ejector and pump are used instead of a single pump to provide backup flow. The switch valve opens after a certain time to reduce heat generation by allowing some hydrogen to bypass the fuel cell during startup.

Source

Fuel cell hydrogen circuit pressure control method to improve stability of hydrogen pressure for fuel cell systems. The method involves staggering the opening times of the hydrogen discharge valve and the drain valve when both are opened at the same time. This prevents sudden pressure drops by allowing the hydrogen discharge to finish before draining starts. The staggered opening times keep the hydrogen cycle and duration unchanged.

Source