Using Liquid Hydrogen in Fuel Cells

A hydrogen fueled high altitude aircraft using a thermodynamic fuel cell system that maximizes efficiency and minimizes environmental impacts. The system compresses inlet air using multiple compressors and cools it using liquid hydrogen to maintain low temperature for the fuel cell. The hydrogen is also compressed and expanded before the fuel cell. The exhaust is cooled to condense water that is collected and expelled as ice. The high efficiency hydrogen conversion enables long range flight with lower fuel volumes. The VTOL aircraft can fly at high altitude with reduced environmental impact.

Valve for hydrogen tanks of fuel cell vehicles to allow rapid opening of the valve to supply hydrogen to the fuel cell stack. The valve has a flexible connection between the pilot and main plungers. The pilot plunger has a blocking body to close the tank-side flow passage and a large opening to connect the tank-side and pipe-side flow passages. When the pilot plunger is raised, the blocking body closes the tank-side passage and the opening connects the passages, rapidly equalizing pressure to allow the main plunger to open quickly.

Fuel cell system operation method to prevent fuel cell degradation when starting up from a cold standby. The method involves recovering boil-off hydrogen gas from the liquid hydrogen tank and supplying it to the fuel cell stack if the hydrogen concentration at the anode falls below a threshold. This prevents air infiltration into the anode during standby. The boil-off gas is compressed before injection to match stack operating pressure. The system uses valves and flow paths to control hydrogen flows between the tank, stack, compression and heating units.

Process to purify hydrogen from a high-pressure tank to a level suitable for use in fuel cells. The process involves flowing the hydrogen stream through an adsorbent purifier to remove contaminants before delivering the purified hydrogen to the fuel cell. Adsorbents like metal organic frameworks (MOFs), zeolites, activated carbon are used to selectively adsorb impurities like CO, CO2, moisture from the hydrogen stream.

Cooling system for hydrogen fuel cells in vehicles like aircraft that uses auxiliary cooling during peak power demands. The fuel cell includes a gasifier to convert liquid hydrogen to gas. The cooling system has a regular coolant circuit sized for normal power levels and an auxiliary bypass circuit that diverts coolant around the gasifier. During peak power, the auxiliary circuit is activated to bypass coolant, using the heat of hydrogen gasification to supplement fuel cell cooling. This prevents overcooling and enables a smaller main coolant system for cruise conditions. A controller manages the cooling systems based on power demand and conditions.

Accurately adjusting hydrogen supply to a fuel cell vehicle from a liquid hydrogen storage tank based on fuel cell conditions. The system uses a bypass line with a valve and orifice to recirculate excess hydrogen back to the tank. A controller adjusts the valve based on tank pressure and flow measurements to optimize hydrogen vaporization from the tank. It also stops the compressor before opening the bypass valve when the vehicle is turned off to prevent overpressure.

A liquid fuel catalytic partial oxidation (CPOX) reformer to produce hydrogen-rich reformates that can be converted to electricity within a fuel cell. The reformer has a novel reactor design with multiple CPOX reactor units in thermal communication. The reactor array allows efficient heat transfer between units for self-sustaining reforming temperatures without external heating. The reactor array also enables compact and scalable reformers with high fuel conversion and low carbon monoxide levels.

Fuel cell system with a method to supply a fuel cell with hydrogen at the correct pressure from low-pressure liquid hydrogen storage facilities. The system uses a buffer tank and heating circuit to transfer hydrogen from the storage tank, heat it, and pressurize it before delivering to the fuel cell at the required pressure. This allows fuel cells to be supplied with hydrogen from low-pressure liquid tanks rather than needing high-pressure gas tanks.

Electrochemical conversion and storage using hydrogen-regenerable liquid fuel for a fuel cell. The fuel cell partially oxidizes the liquid fuel to generate electricity. The liquid fuel is a mixture of alkylated cyclohexanes that can be electrochemically regenerated back to the fuel composition.

Hydrogen generation system that produces hydrogen gas on-demand for fuel cells by heating a liquid reactant and channeling it to a reaction chamber containing a solid hydride. The reaction chamber pressure is measured to start and stop the reaction. The produced hydrogen is filtered, stored in a buffer tank, and supplied to a fuel cell when needed. Heating the liquid reactant allows faster reaction start time and independent reaction rate from hydrogen demand.

A tank-based device that generates power by electrolyzing water to store hydrogen, then reacting it with supplied oxygen to generate electricity. It contains a tank with two sections separated by a membrane and a valve to switch inputs. One section has a flow path connecting openings. Water is supplied at low pressure to flow up through the membrane for electrolysis that stores hydrogen at high pressure in the other section. Oxygen is then supplied at higher pressure to react with the stored hydrogen for power generation.

Electrochemical energy conversion and storage system using a hydrogen-regenerable liquid fuel in fuel cells. The system involves an electrochemical energy conversion device like a fuel cell that receives a liquid fuel containing hydrogenated aromatic compounds. The fuel is catalytically oxidized in the fuel cell to generate electricity. The spent fuel can be regenerated by electrochemical or catalytic reduction.