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  Hydrogen generatorUSPTO Application #: 20070036711Title: Hydrogen generator Abstract: A hydrogen gas generator generates hydrogen gas by mixing two reactants. The generator has a reaction chamber for receiving a solid reactant. The chamber has a reaction product separator impermeable to the solid reactant and a biasing means for biasing reactant products against the separator. The generator also has a liquid reactant dispenser for storing a liquid reactant and is fluidly coupled to the reaction chamber, such that dispensed liquid reactant reacts with the solid reactant in the reaction chamber to produce hydrogen gas and a waste product that are substantially permeable through the separator. The generator also has a product collector coupled to the reaction chamber for collecting hydrogen gas and waste product that have passed through the separator. (end of abstract)
Agent: Jeffer, Mangels, Butler & Marmaro, LLP - Los Angeles, CA, US Inventors: Tobin Joseph Fisher, Jesse Thomas USPTO Applicaton #: 20070036711 - Class: 423648100 (USPTO) Related Patent Categories: Chemistry Of Inorganic Compounds, Hydrogen Or Compound Thereof, Elemental Hydrogen The Patent Description & Claims data below is from USPTO Patent Application 20070036711. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] This invention relates generally to hydrogen generation and in particular, to a hydrogen generator that generates gaseous hydrogen by mixing at least two reactants. BACKGROUND OF THE INVENTION [0002] Modern portable electronic devices are demanding increasing amounts of electrical power and chemical batteries are often the performance bottleneck for such devices. Wireless products, such as personal digital assistants, mobile phones, entertainment devices, and next generation laptops in particular have a great demand for sustained power. For long-term portable operations, fuel cells are an attractive solution. Fuel cells, like batteries, efficiently convert chemical energy into electricity, but have additional advantages, such as higher energy density and the capability for instant refuelling. Fuel cells are typically fuelled by hydrogen gas, but there are technological challenges in storing and delivering hydrogen gas to the fuel cells in a cost effective and efficient manner. One particular challenge is to provide a fuel supply that is inexpensive, safe, light and compact enough to be readily portable yet store enough hydrogen to provide a useful amount of fuel to the fuel cell. State of the art means for storing hydrogen include metal hydride canisters to store hydrogen at relatively low pressures, and pressure tanks to store compressed hydrogen at elevated pressures. Both approaches have drawbacks; for example, metal hydride storage is relatively safe but has a low energy density to weight ratio, and compressed hydrogen storage can have a high energy density to weight ratio but requires high strength and expensive containment solutions. [0003] Research has been conducted into using liquid methanol as a fuel and designing a "direct methanol" fuel cell that electrochemically produces electricity directly from methanol; however, significant technological challenges exist such as preventing methanol cross-over through the electrolyte membrane, and preventing catalyst poisoning by the methanol fuel. [0004] Other efforts have been directed at generating hydrogen gas from a hydrogen-containing fuel solution such as sodium borohydride. In such approaches, the fuel solution is exposed to a catalyst to facilitate the production of hydrogen gas. While this approach is promising, technological challenges exist in containing the caustic fuel solution and preventing leakage, especially when the portable fuel cell system will be used in close proximity to humans. SUMMARY OF THE INVENTION [0005] It is an object of the invention to provide an improved means for generating hydrogen gas. According to one aspect of the invention, there is provided a hydrogen gas generator that generates hydrogen gas by mixing at least two reactants. The generator can be a fuel cartridge especially useful for supplying hydrogen gas to a fuel cell system. The generator has a reaction chamber for receiving a solid reactant. The chamber has a reaction product separator impermeable to the solid reactant and a biasing means for biasing reactant products against the separator. The generator also has a liquid reactant dispenser for storing a liquid reactant and is fluidly coupled to the reaction chamber, such that dispensed liquid reactant reacts with the solid reactant in the reaction chamber to produce hydrogen gas and a waste product that are substantially permeable through the separator. The generator also has a product collector coupled to the reaction chamber for collecting hydrogen gas and waste product that have passed through the separator. [0006] The generator can further comprise a hydrogen gas separator located in the product collector and which is permeable to hydrogen gas and impermeable to the waste product. This separator, for example, can be a gas separation membrane. [0007] The biasing means can be a spring and the solid reactant can be sodium borohydride powder. In particular, the sodium borohydride powder can be compacted into a pill form, and the spring can apply pressure on the pill against the separator. The separator can be a screen having a mesh size that is smaller than the sodium borohydride grain size. [0008] The liquid reactant can be an acidic solution, such as a citric acid solution. In particular, the solution can have a pH of less than 2. [0009] An outer shell can be provided that encloses the reaction chamber, liquid reactant dispenser and product collector; at least part of the shell is sufficiently transparent to view the amount of solid reactant remaining in the generator, thereby acting as a fuel gauge for the generator. BRIEF DESCRIPTION OF THE DRAWINGS [0010] FIG. 1 is a side view of a hydrogen generating fuel cartridge having a fuel cell connector sub-assembly. [0011] FIG. 2 is a partially disassembled view of a fuel cell system having a planar fuel cell stack, a control module, and a connector and pump sub-assembly for coupling to the fuel cartridge sub-assembly and pumping fluid inside the fuel cartridge. [0012] FIG. 3 is a schematic diagram of fluid flow inside the fuel cartridge. [0013] FIG. 4 is a partially transparent side view of the fuel cartridge. [0014] FIG. 5 is a schematic, partially transparent view of the connector and pump sub-assembly and the fuel cartridge connector sub-assembly. [0015] FIG. 6 is a schematic exploded perspective view of the fuel cartridge connector sub-assembly. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION [0016] According to one embodiment of the invention and referring to FIG. 1, a portable fuel cartridge 10 generates hydrogen gas for use as fuel by a fuel cell. Referring to FIG. 2, a portable fuel cell system 12 comprises fuel cells 14 which generate electricity by electrochemically reacting hydrogen gas and oxygen in ambient air. The by-products of the electrochemical reaction also include water and heat. The generated electricity can be used to power portable electrical devices, and to provide heat. The portable fuel cartridge 10 has a connector sub-assembly 15 for physically and fluidly coupling the fuel cell cartridge 10 to the fuel cell system 12. Once coupled, hydrogen gas generated by the fuel cartridge 10 can be delivered into the fuel cell system 12 for use by the fuel cells 14. [0017] One particular use contemplated for the fuel cartridge 10 and fuel cell system 12 is to provide heat and electrical power to personal apparel, such as a jacket. The fuel cell system 12 shown in FIG. 2 is particularly suited for such use. Each fuel cell 14 is arranged in a planar array and electrically connected in series to form a stack. The fuel cells 14 are embedded in a spaced manner within a flexible foam and fabric laminate frame 16. Flexible fuel conduits 18 and electrical conductors 20 interconnect each fuel cell 14. The fuel outlet of one fuel cell 14 is fluidly coupled to the fuel inlet of the adjacent downstream fuel cell 14 by the fuel conduits 18. The fuel cell stack has a dead-ended fuel flow design, in which the last fuel cell 14 is coupled to a purge valve, which can be periodically opened to discharge contaminants and water in the fuel cell stack. The first fuel cell 14 is fluidly coupled to a pumping and connector sub-assembly 22, which is provided with means for fluidly and physically coupling to the connector sub-assembly 15 of the fuel cartridge 10. A control system 23 for controlling the operation of the fuel cell system is electrically communicative with the pumping and connector sub-assembly 22 to control operation of the pump, the purge valve, a voltage sensor and pressure sensor (not shown) coupled to electrical conductors 20, and, a user interface controls and display (not shown). [0018] The fuel cells 14 are planar, passive air breathing proton exchange membrane (PEM) type fuel cells. Each fuel cell comprises a conventional platinum catalyst-coated electrode and Nafion.TM. membrane electrode assembly (MEA), sandwiched by cathode and anode assemblies (not shown). The cathode assembly comprises a conductive mesh in adjacent contact to the cathode side of the MEA, and a conductive plate with multiple openings therethrough in adjacent contact with the conductive mesh; the multiple openings are exposed to air and provide access to oxygen used in the electrochemical reaction. The anode assembly comprises a conductive anode plate with serpentine flow channels in adjacent contact with the anode side of the MEA, and a hydrogen gas manifold plate and having hydrogen inlet and outlet and manifolds that fluidly couple to inlet and outlet ends of the anode plate fuel flow channels. The inlet and outlet manifolds fluidly couple to respective inlet and outlet fuel conduits 18. The MEA also features adhesive around its periphery, and with the adhesive layer, bonds the fuel cell components together. [0019] The fuel cell stack 12 in this embodiment is configured to provide about 10 watts of power; however it is within the scope of the invention to scale up or down the power output by changing the number of fuel cells, or substituting fuel cells of different performance ratings. Continue reading... Full patent description for Hydrogen generator Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Hydrogen generator patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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