CROSS-REFERENCE TO RELATED APPLICATION This application claims benefit of priority of U.S. Provisional Patent Application Ser. No. 61/411,244 filed on Nov. 8, 2010, and to U.S. patent application Ser. No. 13/291,815 filed on Nov. 8, 2011, and to U.S. Provisional Patent Application Ser. No. 61/595,972 filed Feb. 7, 2012, and is related to U.S. patent application Ser. No. 12/750,527 filed on Mar. 30, 2010, the entire disclosures of which are incorporated herein by reference. This application is a continuation of U.S. patent application Ser. No. 13/761,468 filed on Feb. 7, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 13/291,815 filed on Nov. 8, 2011, which claims benefit of priority of U.S. Provisional Patent Application 61/411,244 filed Nov. 8, 2011.
FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT This invention was made with government support under contract number DE-FG36-08G088108 awarded by the U.S. Department of Energy. The U.S. Government has certain rights in this invention.
TECHNOLOGICAL FIELD This technology generally relates to of hydrogen-generating fuel cell systems and methods, and more particularly, to systems and methods for generating hydrogen using sodium silicide, sodium silica gel, or multi-component mixtures that are reacted with water or water solutions.
BACKGROUND Fuel cells are electrochemical energy conversion devices that convert an external source fuel into electrical current. Many fuel cells use hydrogen as the fuel and oxygen (typically from air) as an oxidant. The by-product for such a fuel cell is water, making the fuel cell a very low environmental impact device for generating power.
Fuel cells compete with numerous other technologies for producing power, such as the gasoline turbine, the internal combustion engine, and the battery. A fuel cell provides a direct current (DC) voltage that can be used for numerous applications including stationary power generation, lighting, back-up power, consumer electronics, personal mobility devices, such as electric bicycles, as well as landscaping equipment, and other applications. There are a wide variety of fuel cells available, each using a different chemistry to generate power. Fuel cells are usually classified according to their operating temperature and the type of electrolyte system that they utilize. One common fuel cell is the polymer exchange membrane fuel cell (PEMFC), which uses hydrogen as the fuel with oxygen (usually air) as its oxidant. It has a high power density and a low operating temperature of usually below 80° C. These fuel cells are reliable with modest packaging and system implementation requirements.
The challenge of hydrogen storage and generation has limited the wide-scale adoption of PEM fuel cells. Although molecular hydrogen has a very high energy density on a mass basis, as a gas at ambient conditions it has very low energy density by volume. The techniques employed to provide hydrogen to portable applications are widespread, including high pressure and cryogenics, but they have most often focused on chemical compounds that reliably release hydrogen gas on-demand. Three broadly accepted mechanisms used to store hydrogen in materials are absorption, adsorption, and chemical reaction.
In absorptive hydrogen storage for fueling a fuel cell, hydrogen gas is absorbed directly at high pressure into the bulk of a specific crystalline material, such as a metal hydride. Metal hydrides such as MgH2, NaAlH4, and LaNi5H6, can be used to store the hydrogen gas reversibly. However, metal hydride systems often suffer from poor specific energy (i.e., a low hydrogen storage to metal hydride mass ratio) and poor input/output flow characteristics. The hydrogen flow characteristics are driven by the endothermic properties of metal hydrides (the internal temperature drops when removing hydrogen and rises when recharging with hydrogen). Because of these properties, metal hydrides tend to be heavy and require complicated systems to rapidly charge and/or discharge them. For example, see U.S. Pat. No. 7,271,567 for a system designed to store and then controllably release pressurized hydrogen gas from a cartridge containing a metal hydride or some other hydrogen-based chemical fuel. This system also monitors the level of remaining hydrogen capable of being delivered to the fuel cell by measuring the temperature and/or the pressure of the metal hydride fuel itself and/or by measuring the current output of the fuel cell to estimate the amount of hydrogen consumed.
In adsorption hydrogen storage for fueling a fuel cell, molecular hydrogen is associated with the chemical fuel by either physisorption or chemisorption. Chemical hydrides, such as lithium hydride (LiH), lithium aluminum hydride (LiAlH4), lithium borohydride (LiBH4), sodium hydride (NaH), sodium borohydride (NaBH4), and the like, are used to store hydrogen gas non-reversibly. Chemical hydrides produce large amounts of hydrogen gas upon reaction with water as shown below:
NaBH4+2H2O→NaBO2+4H2
To reliably control the reaction of chemical hydrides with water to release hydrogen gas from a fuel storage device, a catalyst must be employed along with control of the water's pH. Additionally, the chemical hydride is often embodied in a slurry of inert stabilizing liquid to protect the hydride from early release of its hydrogen gas.
In chemical reaction methods for producing hydrogen for a fuel cell, often hydrogen storage and hydrogen release are catalyzed by a modest change in temperature or pressure of the chemical fuel. One example of this chemical system, which is catalyzed by temperature, is hydrogen generation from ammonia-borane by the following reaction:
NH3BH3→NH2BH2+H2→NHBH+H2
The first reaction releases 6.1 wt. % hydrogen and occurs at approximately 120° C., while the second reaction releases another 6.5 wt. % hydrogen and occurs at approximately 160° C. These chemical reaction methods do not use water as an initiator to produce hydrogen gas, do not require a tight control of the system pH, and often do not require a separate catalyst material. However, these chemical reaction methods are plagued with system control issues often due to the common occurrence of thermal runaway. See, for example, U.S. Pat. No. 7,682,411, for a system designed to thermally initialize hydrogen generation from ammonia-borane and to protect from thermal runaway. See, for example, U.S. Pat. Nos. 7,316,788 and 7,578,992, for chemical reaction methods that employ a catalyst and a solvent to change the thermal hydrogen release conditions.
In view of the above, there is a need for an improved hydrogen generation system and method that overcomes problems or disadvantages in the prior art.
SUMMARY The hydrogen fuel cell power system described below includes three primary subsystems, including a fuel cell, a water feed tray system, and a fuel cartridge. This system is designed for the class of fuel cell systems called “water-reactive.” In a water-reactive system, water (or a liquid solution) is combined with a powder to generate hydrogen for a fuel cell system. These reaction types can use a range of powders such as sodium silicide, sodium silica gel, sodium borohydride, sodium silicide/sodium borohydride mixtures, aluminum, and others. Activators, catalysts, or additives can be added to the powder to control water dispersion through the powder or water absorption of the reaction by-products. Additives to the powder can also include defoamers, such as oils, as well as similar materials to distribute local reaction sites and/or temperatures to result in a more uniform reactivity and heat distribution in the fuel cartridge and to control reaction conditions, including, for example, the chemical and physical nature of the reaction products and by-products. Powder size can be controlled to facilitate water transport, reaction rate, and byproduct water absorption. Activators, catalysts, or other additives can also be added to the water in order to form a liquid solution at varying conditions.
The reactant fuel material can include stabilized alkali metal materials such as silicides, including sodium silicide powder (NaSi), and sodium-silica gel (Na-SG). The stabilized alkali metal materials can also be combined with other reactive materials, including, but not limited to, ammonia-borane (with or without catalysts), sodium borohydride (mixed with or without catalysts), and an array of materials and material mixtures that produce hydrogen when exposed to heat or aqueous solutions. The mixture of materials and the aqueous solutions can also include additives to control the pH of the waste products, to change the solubility of the waste products, to increase the amount of hydrogen production, to increase the rate of hydrogen production, and to control the temperature of the reaction. The aqueous solution can include water, acids, bases, alcohols, and mixtures of these solutions. Other examples of the aqueous solutions can include methanol, ethanol, hydrochloric acid, acetic acid, sodium hydroxide, and the like. The aqueous solutions can also include additives, such as a coreactant that increases the amount of H2 produced, a flocculant, a corrosion inhibitor, or a thermophysical additive that changes thermophysical properties of the aqueous solution. Example flocculants include calcium hydroxide, sodium silicate, and others, while corrosion inhibitors can include phosphates, borates, and others. Further, the thermophysical additive can change the temperature range of reaction, the pressure range of the reaction, and the like. Further, the additive to the aqueous solution can include mixtures of a variety of different additives.
The claimed invention can include a removable/replaceable fuel cartridge that is inserted into a water feed tray system. A fuel cell can be connected to the water feed tray system encompassing the fuel cartridge. In the process of this connection, the fuel cartridge forms a water connection with the water feed tray and a hydrogen gas connection with the fuel cell. The water feed tray can be designed to store and be re-filled with water. The water feed tray system can be designed not to output water until the water feed tray is connected to a fuel cartridge. As water enters the fuel cartridge from the water feed tray, hydrogen is generated and delivered to the fuel cell. Upon disconnection of the water feed tray and fuel cell, a valve in the water tray closes, which in turn stops water flow in the water tray. In addition, a spring mechanism in the water feed tray ejects the fuel cartridge from the water feed tray which disconnects the water flow path to the fuel cartridge. Either or both of these configurations and techniques stop water flow and ceases production of hydrogen. In another example implementation, a mechanical flow valve or similar mechanism can be employed to stop water flow into the fuel cartridge while the fuel cartridge remains connected. This in turn, stops hydrogen from being generated. The flow valve can be a physical switch controlled by a user or an electronically controlled switch. Likewise, in another example implementation, the flow can be controlled by a pump to turn off water flow while the fuel cartridge is still engaged or to pump water if flow is desired.
In one example implementation, the water feed tray and fuel cell can be constructed to effectively function as a single sub-system with a replaceable fuel cartridge being a removable/replaceable component. In another implementation, the water feed tray and fuel cartridge can be constructed to effectively function as a single sub-system with the entire sub-system being removable/replaceable.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a diagram of a hydrogen fuel cell power system, including a fuel cell, water feed tray, and a fuel cartridge in accordance with the claimed invention.
FIG. 2 illustrates a water feed fuel cell system and fuel cartridge and its related inputs and outputs.
FIG. 3 shows an example of a water feed fuel cell system with a refillable water door and a fuel cartridge in accordance with the claimed invention.
FIGS. 4A-4B illustrates structural characteristics of a water feed tray shown with a fuel cartridge inserted in the water feed tray.
FIG. 5A shows an exploded view of a water feed fuel cell system shown with a fuel cartridge. FIG. 5B shows a side view of the water tray insert. FIG. 5C shows the bottom of the water tray insert.
FIGS. 6A and 6B illustrate a sliding lock mechanism used in a hydrogen fuel cell power system in an open view and in a closed view in accordance with the claimed invention.
FIG. 6C illustrates water feed tray, fuel cartridge, and fuel cell sub-systems with a latch connection mechanism.
FIG. 6D is a cross-sectional view of a water feed tray and fuel cartridge in accordance with the claimed invention.
FIG. 7A is a perspective view of a water feed tray with a fuel cartridge inserted. FIG. 7B is a side view of a water feed tray with a fuel cartridge inserted. FIG. 7 C is a top view of a water feed tray with a fuel cartridge inserted.
FIG. 8A illustrates a bellows spring assembly configured to store, pressurize, and output water in a water feed tray in accordance with the claimed invention.
FIGS. 8B and 8C illustrate a bellows spring assembly in accordance with the claimed invention in a nominal compressed state and in a loaded state, respectively.
FIGS. 8D and 8E illustrate a bellows spring assembly and locking shelf in accordance with the claimed invention in a disengaged position and in an engaged position, respectively.
FIG. 8F illustrates a bellows access door in accordance with the claimed invention in an engaged position.
FIG. 9A is a side view of a tube-connection water limiting orifice in accordance with the claimed invention. FIG. 9B is a cross-sectional view of the section A-A as indicated in FIG. 9A. FIG. 9C is a perspective view a tube-connection water limiting orifice in accordance with the claimed invention.
FIG. 10A shows a top view of a disk-type water flow limiting orifice in accordance with the claimed invention. FIG. 10B shows a side view of a disk-type water flow limiting orifice in accordance with the claimed invention. FIG. 10C shows a perspective view of a disk-type water flow limiting orifice in accordance with the claimed invention.
FIG. 11 illustrates structural components for the top of a bellows assembly to lock the tray door open when refilling water in a fuel cell system in accordance with the claimed invention.
FIGS. 12A and 12B are top and perspective views, respectively, that illustrate a locking mechanism to lock the fill door open when refilling water in a fuel cell system in accordance with the claimed invention.
FIGS. 13A and 13B are cross sectional views illustrating structural details of a fuel cartridge for use in a hydrogen fuel cell power system in accordance with the claimed invention.
FIG. 13C is front view of an angled needle value in accordance with the claimed invention. FIG. 13D is a perspective view of an angled needle valve in accordance with the claimed invention.
FIG. 14A is a side view which illustrates further structural details of a fuel cartridge canister for use in a hydrogen fuel cell power system in accordance with the claimed invention. FIG. 14B is another side view which illustrates further structural details of a fuel cartridge canister for use in a hydrogen fuel cell power system in accordance with the claimed invention. FIG. 14C is top view which illustrates further structural details of a fuel cartridge canister for use in a hydrogen fuel cell power system in accordance with the claimed invention. FIG. 14D is yet another side view which illustrates further structural details of a fuel cartridge canister for use in a hydrogen fuel cell power system in accordance with the claimed invention. FIG. 14E is a perspective view which illustrates further structural details of a fuel cartridge canister for use in a hydrogen fuel cell power system in accordance with the claimed invention. FIG. 14F is another perspective view which illustrates further structural details of a fuel cartridge canister for use in a hydrogen fuel cell power system in accordance with the claimed invention.
FIG. 14G is a perspective view which illustrates a reactant retention screen for a fuel cartridge in accordance with the claimed invention. FIG. 14H is a top view which illustrates a reactant retention screen for a fuel cartridge in accordance with the claimed invention.
FIG. 15A shows a chemical scrubbing pathway for acquiring high purity hydrogen by controlling the exit flow over a filter bed integrally formed in a cap of a fuel cartridge in accordance with the claimed invention.
FIG. 15B shows a chemical scrubbing maze for acquiring high purity hydrogen by controlling the exit flow over a filter bed integrally formed in a cap of a fuel cartridge in accordance with the claimed invention.
FIG. 15C shows a perspective view of an overmolded face seal gasket incorporated into a cap of a fuel cartridge in accordance with the claimed invention.
FIG. 15D shows a side view of an overmolded face seal gasket incorporated into a cap of a fuel cartridge in accordance with the claimed invention.
FIG. 16A shows a tool to crimp a metallic fuel cartridge body to a plastic fuel cartridge cap for use in a hydrogen fuel cell power system in accordance with the claimed invention.
FIG. 16B is a cross-sectional view of a fuel cartridge that has been assembled using a roll-over crimp and the crimping tool of FIG. 16A.
FIG. 17A shows an example of a perspective view of a cartridge valve integrally mounted to a fuel cartridge cap in accordance with the claimed invention. FIG. 17B shows an example of a top view of a cartridge valve integrally mounted to a fuel cartridge cap in accordance with the claimed invention. FIG. 17C shows an example of a closeup view of area C in FIG. 17D. FIG. 17D shows an example of a cross sectional view of the section A-A as indicated in FIG. 17B.
FIG. 18A shows a canister with a coiled reaction feed tube for use in a hydrogen fuel cell power system in accordance with the claimed invention.
FIG. 18B shows a canister with a T-fitting and coiled reaction feed tube for use in a hydrogen fuel cell power system in accordance with the claimed invention.
FIGS. 19A and 19B show an automatic mechanical water control valve and plunger for use in a hydrogen fuel cell power system in accordance with the claimed invention in an open position and a closed position, respectively.
FIG. 20 shows springs to “eject” cartridges from the tray of a hydrogen fuel cell power system in accordance with the claimed invention.
FIGS. 21A and 21B show a normally closed needle valve for use in a hydrogen fuel cell power system in accordance with the claimed invention in a perspective view and a cross sectional view, respectively.
FIG. 22 shows a system in accordance with the claimed invention charging a cellular telephone.
FIG. 23A shows a silicone sheet for fluid isolation in a fuel cell system in accordance with the claimed invention.
FIG. 23B shows a water feed tray needle and a silicone sheet providing fluid isolation in a fuel cell system in accordance with the claimed invention.
FIG. 23C shows a bottom view of a silicone sheet for fluid isolation in a fuel cell system in accordance with the claimed invention.
FIGS. 24A and 24B illustrates a segmented fuel cartridge and a rotatable actuator manifold in accordance with the claimed invention as the rotatable actuator manifold moves from a first position to a second position, respectively.
FIGS. 25A and 25B schematically illustrate a rotatable actuator manifold in accordance with the claimed invention in side and top views, respectively.
FIGS. 26A and 26B schematically illustrate a magnetic poppet safety stop valve in accordance with the claimed invention in open and closed views, respectively.
DETAILED DESCRIPTION FIG. 1 shows one example of a water-reactive, hydrogen-fueled power system 100 in accordance with the claimed invention. The system 100 includes a fuel cartridge 120, a water feed tray 130, and a fuel cell 110. Fuel cartridge 120 includes a reactant fuel material 177. Fuel cartridge 120 can be a physical device separate from water feed tray 130 or can be integral to water feed tray 130.
The reactant fuel material 177 can include stabilized alkali metal materials, including powders such as sodium silicide, sodium silica gel, sodium borohydride, sodium silicide/sodium borohydride mixtures, aluminum, and others. Activators, catalysts, and/or additives can be added to the reactant fuel material 177 to control water dispersion through the reactant fuel material 177 or water absorption of the reaction by-products. Additives to the reactant fuel material 177 can also include defoamers, such as oils, such as mineral oils, as well as other materials to distribute local reaction temperatures to result in a more uniform heat distribution in the fuel cartridge 120. The reactant fuel material 177 powder size can be controlled to facilitate water transport, reaction rate, and byproduct water absorption. For example, the powder size of the reactant fuel material 177 can be varied from less than 1 mm to 9 mm. In one example implementation, the powder size of the sodium silicide was from approximately 4 mm to 6 mm. This powder size is made large enough to eliminate problematic binding when water or another aqueous solution is added to the fuel cartridge. Instead of adding water to a too-fine powder that is susceptible to binding when wet, this reactant fuel configuration allows for the added water 199 to effectively reach fresh powder as the water 199 is added to the fuel cartridge 120.
The reactant fuel material 177 can also include stabilized alkali metal materials such as silicides, including sodium silicide powder (NaSi), and sodium-silica gel (Na-SG). The stabilized alkali metal materials can also be combined with other reactive materials, including, for example, ammonia-borane (with or without catalysts), sodium borohydride (mixed with or without catalysts), and an array of materials and material mixtures that produce hydrogen when exposed to heat or aqueous solutions. In one example implementation, the reactant fuel material 177 includes stabilized alkali metal materials and such optional coreactants.
The water feed tray 130 can be filled with water 199 by a user. Activators, catalysts, or other additives can also be added to the water 199 in order to form a liquid solution. The water feed tray 130 includes a mechanism to pressurize the water 199. One example pressurization mechanism shown in FIG. 1 can include a spring assembly 231 in bellows 160 that pressurizes water 199 to flow through check valve 140 and poppet 150 and into fuel cartridge 120. The spring assembly 231 can be mounted in the bellows to “push” the water through the check valve 140 or can be mounted in the bellows to “pull” the water toward and through the check valve 140, depending upon the spring characteristics and the desired delivery mechanism. The pressurization mechanism can be a bellows assembly, a spring assembly, a piston assembly, and the like, as discussed further with regard to FIGS. 2 and 8 below. Spring assemblies, piston assemblies, and other pressurization assemblies can be located outside the bellows to provide pressure to the bellows to pressurize the water, or can be located within the bellows to provide direct pressure to the water as shown in the example in FIG. 1. For example, FIG. 2 shows an example spring assembly 221 located outside the bellows 260. Outside spring assembly 221 exerts a force on the bellows 260 and the water 199 in the bellows.
In addition, bellows assemblies can be self-pressurized as well. For example, a bellows assembly can be made of an elastic material known in the art such as silicone, other rubbers and elastomers, including but not limited to, latex, polychloroprene, polyester, nylon, polyurethane, and the like, that expand and contract as a volume of water is added to the bellows assembly. In some self-pressurized examples, an aqueous solution such as water is added to the bellows assembly, which expands to hold the volume of water. The volume of water stretches the material of the bellows assembly in a similar fashion to the manner in which a balloon or an inflatable bag expands when a volume of water is added to the balloon. Once the desired volume of water is added to the bellows assembly, the poppet (valve) can be closed to prevent the water from leaving the bellows until the reaction is started. To start the reaction, the poppet on the bellows assembly can be opened to allow the aqueous solution to flow to the reactant material. The bellows assembly then begins to return to its non-expanded size, which provides pressure to the water, and the water flows to the fuel cartridge 120. The poppet 150 can be actuated by a physical connection of the fuel cell to the water tray. The poppet may also be actuated by other mechanical or electro-mechanical mechanisms may be used. Other valve designs can be utilized to perform the starting and stopping poppet function.
In another example, FIG. 8A shows an exploded view of a reservoir portion 832 of the water feed tray 130 that incorporates a spring assembly 834 that is fitted in the water feed tray 130 to pressurize the water 199. Spring assembly 834 can be an inverted spring where the inner coil is pulled through the outer coil during use. The inverted spring effectively increases the length of the spring assembly 834, and creates a more linear force range over the displacement range. This linear force can then be transferred to the water and/or to a bellows assembly holding the water. As the inverted spring provides force to pressurize the water, the inverted spring decreases in length, however even when the inverted spring reaches the state where it is flat, the spring is still in a stressed state (providing force). This allows the water to be under pressure even when almost all water (in the bellows or in the reservoir portion of the water tray) has been used. When unlocked, the spring assembly 834 imparts a force on the water by pulling on the bellows door assembly (for example, resulting in pressurized water of approximately 2-4 psi). The pressure is used to feed the water flow from water tray 130 to fuel cartridge 120 to begin the reaction. The spring assembly 834 can be a traditional coiled spring 872 or can be made of a stamped piece of metal that is elongated and heat treated such that when the spring assembly 834 is flat in the bellows assembly 260 it is still in a stressed state (remains under pressure). In this fashion, the spring mechanism is configured such that there is positive spring force that results in pressurized water even when almost all the water has been fed out of the bellows assembly 260.
Returning to FIG. 1, pressurized water 199 or liquid solution flows into the fuel cartridge 120 from the water feed tray 130 through a check valve 140 and poppet 150. Hydrogen 188 is generated inside the fuel cartridge 120 and flows into the fuel cell 110. A diagram showing the flow of water 199 pressurized by a bellows assembly 260 through a poppet 150 and check valve 140 into a fuel cartridge 120 is shown in further detail in FIG. 2. The water 199 shown in FIG. 2 enters a water chamber and bellows assembly 260. For simplicity water 199, both in and out of the bellows assembly is shown as reference numeral 199. When the water 199 reacts with the reactant fuel material 177 in the fuel cartridge 120, hydrogen 188 is produced and flows from the fuel cartridge 120 to the fuel cell (not shown separately in FIG. 2).
Spring-driven reaction systems can use the characteristics of the spring to monitor and determine the amount of the reactant fuel material that remains in the reactor chamber, such as fuel cartridge 120. The determination can be made either directly or indirectly. With a known amount of reactant fuel material in the fuel cartridge at the beginning of a reaction, the pressure in the fuel cartridge is monitored. As the pressure inside the fuel cartridge changes, the amount of water added to the reaction can be determined, which provides an indication of the amount of reactant fuel material that was used in the reaction. Subtracting the amount of reactant fuel material used from the amount of reactant fuel material at the start of the reaction provides the amount of reactant fuel material remaining for use in the reaction. For example, at the beginning of a reaction, a known amount of reactant fuel material exists in the fuel cartridge 120. A spring, such as spring 221 in FIG. 2 develops pressure in the water chamber (bellows assembly 260), and water 199 is injected into the fuel cartridge 120 via check valve 140 and poppet 150. Hydrogen is generated as water 199 contacts the reactant fuel material 177 in the fuel cartridge 120. As spring 221 provides the pressure to inject water 199 into the fuel cartridge 120, hydrogen is generated, which creates pressure in the fuel cartridge 120. The pressure created in the fuel cartridge 120 applies an opposite force on the water chamber (bellows assembly 260), when the pressure in the fuel cartridge equals the water pressure created by the flow, the water flow will stop which in turn means that additional hydrogen generation will also stop. In the event that the hydrogen pressure in the fuel cartridge 120 inadvertently exceeds the water pressure created by the water flow, the check valve will not allow the water to develop a higher pressure than the pressure determined by the spring. Without the check valve, the system could oscillate uncontrollably. As the reaction continues over time, the effective spring force can be seen as decaying over that same time period due to force versus deflection characteristics of the spring. As the displacement of the spring changes over time, the water pressure changes, which is directly related to the average hydrogen pressure in the fuel cartridge over the same time. A measurement of spring displacement, water pressure, or hydrogen pressure can be therefore used to indirectly determine the state of the reaction. For example, the system may be characterized so that at the beginning of the reaction, the developed pressure in the fuel cartridge is 3 psi but near the end of the reaction, the pressure in the fuel cartridge is 1 psi. A microcontroller with a look-up table (database) can be used to measure this pressure and to determine the state of the reaction. The pressure sensor and the microcontroller may reside in the fuel cell, in the water tray, in the pathway between the water tray and the fuel cartridge, in the fuel cartridge, or in any combination of them.
The spring force is based upon the physical characteristics of the spring, such as material, wire diameter, diameter of the shaft, internal and external diameters, pitch, block length, free length, number of coils, spring rate, and lengths at force. The spring can be of any of a wide variety of different types such as coil, leaf, or clock springs. Based upon these physical characteristics, the effective force produced by the spring can be used to determine the hydrogen pressure in the reactor chamber, the amount of reactant fuel material that has been reacted or similarly, how much reactant fuel material remains in the reactor chamber. Likewise, the effective spring force can be monitored using a force gauge, such as force gauge 288 to monitor, determine, and report the effective force of the spring and thereby the pressure produced by the hydrogen gas. Of course the force gauge 288 can also be installed in the reactor chamber to monitor the hydrogen pressure produced from the reaction. Similarly, a pressure gauge can also be used. From these pressure and/or force measurements, the amount of reactant fuel material remaining in the fuel cartridge 120 can be determined. For example, a simple look up table and/or database mapping can be used to map effective spring force to the amount of reactant fuel material remaining in the fuel cartridge 120. Likewise, a similar table can be employed mapping the hydrogen pressure in the fuel cartridge 120 to an amount of reactant fuel that has been reacted. Combinations and variations of these database mappings/look up tables can also be employed.
Returning to FIG. 1, the fuel cell 110 utilizes the hydrogen 188 from the fuel cartridge 120 and oxygen from the air to create an electric potential. Once the electric potential is created, the system 100 can be used to charge and/or run electronic devices, such as a cellular telephone 2201 as shown in FIG. 22. Adapter cables 2202 can be fashioned to operably connect the system 100 to the electronic devices. Of course, other electronic devices may use the electric potential created by the system 100 to charge, or run, or operate. In this disclosure, the fuel cell 110 is considered to be a fuel cell system. For example, a fuel cell system can contain multiple fuel cells, a fuel cell stack, a battery, power electronics, control electronics, electrical output connectors (such as USB connectors), hydrogen input connectors, and air access locations to provide air for both cooling and for the reaction.
The fuel cell (system) 110 can be attached to the water feed tray 130 and/or fuel cartridge 120 using a number of different techniques. As shown in FIG. 6A, for example, the fuel cartridge 120 is inserted in water feed tray 130, which is then secured to fuel cell 110 using guide rails 662a, 662b on the water feed tray 130 and guide rail 664 on the fuel cell 110. As the fuel cell 110 is slid along direction arrow F onto the water feed tray 130, spring latch 666 is displaced until a calibrated notch (not shown separately) is engaged to securely prevent bi-directional sliding of the system 100. FIG. 6B shows the secured position of the system.
An alternative manner of mechanically securing the fuel cell 110 to the water feed tray 130 and fuel cartridge 120 is shown in FIG. 6C. In this example, the fuel cell 110 is not mechanically slid and locked to the fuel cartridge 120 and/or water feed tray 130, but rather, the fuel cartridge 120 is captured by the water feed tray 130 and fuel cell 110 using latches 668a, 668b. Latches 668a, 668b can be used to securely clamp the water feed tray 130 to the fuel cell 110 during hydrogen generation operations by using compressive force for engagement with latch locking points 669a, 669b on the water feed tray 130 to prevent the fuel cell 110, water feed tray 130, and fuel cartridge 120 from separating.
Regardless of the manner in which the fuel cell 110 is ultimately secured to the water feed tray 130 and fuel cartridge 120, when properly connected, the fuel cell 110 pushes on the poppet 150 in the water feed tray 130 while simultaneously pushing the fuel cartridge 120 into the water feed tray 130 and onto the water tray needle 682 as shown in the side view depicted in FIG. 6D (and schematically in FIGS. 1 and 2). The valve poppet 150 and needle 682 combination are configured such that when the fuel cell 110 is engaged to the water feed tray 130, the poppet 150 is depressed, and pressurized water 199 from the bellows 260 is allowed to travel through the water feed tray 130 along water pathway 535, through the water tray needle 682, and into the fuel cartridge 120. To avoid spillage, the water feed tray 130, fuel cartridge 120, and fuel cell 110 are properly dimensioned with appropriate tolerances so that water 199 flows only when water feed tray needle 682 is inserted into a grommet 625 (see also needle valve 1329 in FIGS. 13A and 13B) within the fuel cell cartridge 120. Once water 199 reaches the reactant fuel material 177 in the fuel cartridge 120, hydrogen gas will form generating a pressure inside the fuel cartridge 120. The generated pressure will supply hydrogen 188 to the fuel cell 110 while also serving to limit the amount of additional water 199 that is input from the bellows 260 into the fuel cartridge 120.
As also shown in FIG. 6C, spring mechanism 670 can be employed to assist in ejecting the fuel cartridge 120 from the water feed tray 130. For example, the spring mechanism 670 can impart a physical force to fully move/eject the fuel cartridge 120 from the water feed tray 130 or to partially move/eject the fuel cartridge 120 from the water feed tray 130 to make it easier for a user to fully remove and/or to disconnect connect the fuel cartridge 120 from a water inlet point, such as the water inlet point 122 as shown in FIG. 2. Additionally, as shown in FIG. 6D, the spring mechanism 670 raises the fuel cartridge off of the water feed tray needle 682, so even if the plunger 533 in FIG. 5A was accidentally pressed, hydrogen production would be prevented. An additional view of the water feed tray 130 illustrating spring mechanism 670 is shown in FIG. 20.
Additional structural and operation details regarding the system 100, including water feed tray 130, fuel cartridge 120, and fuel cell 110 are provided below. The additional disclosure materials below describe additional structural and functional details of the water feed tray, fuel cartridge, and fuel cell in accordance with the claimed invention.
Water Feed Tray Feeding FIG. 4A illustrates a water feed tray 130 with a fuel cartridge 120 inserted. The fuel cartridge 120 shown includes an aluminum canister 421 and a plastic canister cap 423 with a hydrogen port 424. Water feed tray 130 can be divided into three major sections, including a bellows/water feed section 491, valve and poppet section 492, and fuel cartridge holder section 493. The water feed tray 130 can include a guide rail 662 for engaging or attaching the fuel cell 110. The water feed tray 130 can be made of an insulating plastic, such as a thermoplastic, polycarbonate, PC/ABS blend, or other material that provides for safe handling of the fuel cartridge 120. As shown in a side view in FIG. 4B, the example insulating plastic pattern can include slits 494 or other vent holes in the plastic for heat transfer and to allow for heat generated from the fuel cartridge 120 to dissipate as water 199 is fed to the fuel cartridge 120. Further, spray-on or other heat insulating materials, such as foams, aerogels, silicones, and the like can be added to the canister to provide insulation for a user and to allow safe handling and/or to provide thermal insulation to raise internal reaction temperature. Additionally, the insulating plastic can include feet 495 to provide a stand for the water feed tray 130. The insulating plastic can also include a tilted boss 496 for additional strength and durability and can also be used as an alignment device to ensure proper mating of the water feed tray and fuel cell 110.
The water feed tray 130 includes the water 199 that is pressurized and delivered to the fuel cartridge 120. As outlined above and shown in FIG. 2, the water feed tray 130 can utilize a bellows assembly 260 to contain and hold the water 199. Alternative methods of holding, pressurizing, and delivering the water 199 can also be used as outlined above. For example, sliding pistons, collapsing diaphragms, inflatable diaphragms, and other deformable containers can be used as well as electrical pumps, such as piezoelectric pumps, and the like.
As shown in FIG. 3, the water feed tray 130 can have an access door 336 to allow the user to easily fill or scoop water into the water feed tray 130. In another example implementation, the water feed tray can be sealed and a pump, syringe, or other pressurized water source can be used to fill the water feed tray 130 or to push water into a bellows assembly. In one example implementation, the access door 336 can act as a lever arm allowing for easier loading of a spring (such as inverted spring 834 shown in FIG. 8A and stamped plates in FIGS. 8B and 8C) that can provide water pressure.
As shown in FIGS. 3 and 8F, the water feed tray 130 can have an access door 336 to allow the user to easily fill or scoop water into the water feed tray 130. A user can press down on bellows access door 336 to disengage a locking shelf 815 and prepare the water feed tray 130 for use. Access door 336 can provide access to the bellows (not shown separately in FIG. 3) to contain and hold the water 199. For example, the door/bellows combination can be rotated or translated to put the spring 834 into a locked position, which loads the spring 834. In the locked position shown in FIG. 8E, the user can easily add more water to the bellows 260 without the bellows self-collapsing. Once the bellows 260 is filled with water 199, the user locks the bellows door 336 closed as shown in FIG. 8F, which seals the water 199.
An example of the spring 834 in its nominal (down) position is shown in FIG. 8B. When fully assembled in the water feed tray 130, the spring 834 is pulled through itself in the opposite direction (up) to load as shown in FIG. 8C.
As further shown in FIG. 8D, the bellows 260 assembly can then be rotated or translated off a locking shelf 815 to activate the spring 834. The spring 834 then pressurizes the water 199 in the bellows 260 where it can flow to fuel cartridge 130. Of course other locking mechanisms can be used to gain access to the bellows 260 to add water 199 and to load the spring 834. For example, locking pins 1138a, 1138b, 1139 can be used to secure the bellows 260 as shown in FIG. 11. Additionally, sliding rods 1242 can be used to gain access to the bellows 260 to add water 199 and to load the spring 834. Examples of the sliding rods 1242 are shown in a locked position in FIG. 12A and in an unlocked position in FIG. 12B.
As shown schematically in FIGS. 1 and 2, after the locking mechanism is disengaged, the water 199 is ready to be delivered to the fuel cartridge 120. FIG. 5A shows an exploded view of the water feed tray 130, a water tray insert 531, and a fuel cartridge 120 and water pathway 535 that connects a bellows assembly (not shown separately in FIGS. 5A-5C) to the fuel cartridge 120.
In one example implementation, a plunger 533 in poppet 150 is in line between the bellows assembly containing the water and the fuel cartridge 120. A detailed drawing of the plunger 533 and poppet 150 in an open position (water 199 flowing from bellows to fuel cartridge 120) is shown in FIG. 19A, and a drawing of the plunger 533 and poppet 150 in a closed position (water 199 not flowing from bellows to fuel cartridge 120) is shown in FIG. 19B. The plunger 533 keeps water 199 from leaving the bellows assembly during storage or while the user is preparing a fuel cartridge 120 or loading a fuel cartridge 120.
During storage, transportation, and in other instances where safety dictates that the water-reactant fuel reaction not initiate, the plunger 533 in poppet 150 can be locked in its closed position so that no water can flow to the fuel cartridge. This interaction works as a stop valve on the water feed tray. The action of closing the plunger 533 can be actuated by additional mechanical means such as levers, switches, actuators, and electrical switching means such as an electrically actuated switch, magnetic switch closures mounted on the fuel cell, the water tray, and/or the fuel cartridge. An example of a magnetic stop valve closure mounted on the fuel cell is illustrated schematically in FIGS. 26A and 26B. In FIG. 26A, a magnet 2611 in the fuel cell (not shown separately) is coupled to the water feed tray/fuel cartridge combination, which contains a magnetic poppet 2622. The magnet 2611 acts upon the poppet 2622 holding the poppet 2622 above the water path 2633 allowing water to flow as shown by reference arrow W. In FIG. 26B, the magnet 2611 is moved away from magnetic poppet 2622 (such as when the fuel cell is detached from the water feed tray/fuel cartridge combination). This allows the poppet to move into the water path 2633 blocking the flow of water through water path 2633. In this closed position, water can only flow back and forth as shown by reference arrows B and F. Other mechanical, electro-mechanical, or magneto-mechanical devices can also be used to actuate the valve and to prevent water from traveling from the pressurized water chamber into the fuel cartridge until the water feed tray and/or the fuel cartridge is connected to the fuel cell. In the case where the fuel cartridge and the water feed tray are incorporated in an integrated unit, the switching device can be used to prevent water flow until the integrated unit is connected to the fuel cell. In another example implementation, the stop valve could simply be locked in shipping, and a user would pull the stop valve mechanism actuating the cartridge, and allowing the reaction to start.
Returning to FIGS. 1, 2, 19A, and 19B, the plunger 533 is opened and water 199 is allowed to travel along water pathway 535 when the fuel cell 110 is engaged and locked into position with the water feed tray 130 as described above. The water tray insert 531 can be integral to the water feed tray 130 or can be attached using a number of sealing mechanisms including glue/epoxy, ultrasonic bonding, physical compression, gaskets, and the like. An example of an ultrasonic welding bead is shown as reference numeral 572.
When the fuel cell 110 is disengaged from the water feed tray 130, the water flow will stop as a spring 537 puts the valve spring into its normally closed position (shown in FIG. 19B). The plunger 533 and/or poppet 150 can also be an electronically actuated valve(s) where a sensor(s) is used to detect connection/disconnection of the fuel cartridge 120, water feed tray 130, and fuel cell 110. In one example implementation, a permanent magnet is constructed as part of the valve assembly. An electrical coil and appropriate drive electronics can be located in the fuel cell 110, which can be integrated with existing fuel cell control electronics. Additionally, a miniature pump can also be used to deliver the water under pressure. A miniature pump also allows for control of the water flow rate which can generate a hydrogen pressure. A control scheme can be used to control the pressure to a desired value or within a nominal range.
In addition to the spring mechanism 670 shown in FIG. 6C and FIG. 20 that can be employed to assist in ejecting the fuel cartridge 120 from the water feed tray 130, a spring mechanism 497 (shown in FIG. 4B) can also be used to push the fuel cartridge 120 against the fuel cell 110 to provide the force required for a gas (hydrogen) seal. The spring mechanism 497 can be a physical spring, such as helical or coil springs, compression springs, flat springs, beams, and the like. For example, the spring mechanism 497 can impart a physical force to fully seal and stabilize the fuel cartridge 120 to the fuel cell 110 such that the hydrogen port 424 of the fuel cartridge 120 provides hydrogen to the fuel cell 110 without leakage.
As described above, when a spring 834 is used in conjunction with a bellows assembly 260 to pressure the water 199, the system 100 provides an additional mechanism to prevent transient high pressure spikes from reverse-pressurizing the spring 834. The high pressure spikes can result in perturbations in pressure and water delivered at an oscillating rate. If the spring 834 is reverse-pressurized, higher water surges can result in oscillatory and/or a positive feedback situation resulting in unintended escalating pressure spikes. Multiple methods can be utilized to prevent transient high pressure spikes from reverse-pressurizing the spring 834. For example, in one implementation outlined above with regard to FIGS. 1, 4, and 8, a check valve 140 can be used to isolate pressure spikes to the fuel cartridge holder section 493 side of the water feed tray 130. The check valve 140 in tandem with the spring 834 provides pressure regulation to isolate pressure spikes and to eliminate oscillating amounts of water delivered to the reactant fuel material 177. The check valve 140 can be integral to the water 199 storage and feed, located separately in a check valve and poppet housing 745 or included as part of fuel cartridge 120. When the check valve 140 is placed prior to the reactant fuel mixture 177, perturbations in pressure can be eliminated and uniform volumes of water 199 can be delivered to the reactant fuel mixture 177 in the fuel cartridge 120. Other mechanisms to prevent transient high pressure spikes from reverse-pressurizing the spring can also be employed, such as a controlled on/off valve can be used to eliminate perturbations in pressure and water delivered at an oscillating rate. Another device that can be used is a bleed-off valve, which can simply vent any excess pressure either by way of a valve or through the fuel cell 110. In each case, a check valve in combination with the spring can be used to eliminate fluctuations in water pressure and flow rates to the fuel cartridge 120.
As shown in FIG. 18B, a water flow limiter, such as water flow limiting orifice 1886 can be used to prevent excessive water flow from being delivered to the fuel cartridge 120 in certain transient conditions. The water flow limiting orifice 1886 can serve as a safety limiter of the water input rate. The water flow limiting orifice 1886 can regulate the rate of the delivered water to provide sufficient time for the chemical reaction between the reactant fuel material 177 and the water 199 to generate hydrogen pressure. Failure to limit the water flow can cause excessively large amounts of water to be delivered to the fuel cartridge 120 resulting in high pressure spikes. A flow limiting orifice can be incorporated in the fuel cartridge, water feed system, or both. For example, in one implementation shown in FIG. 18B, the water orifice 1886 could be 0.007 inch hole in a solid disc that is pushed into the tubing or the grommet. A detailed view of a tube connection water flow limiting orifice is shown in FIGS. 9A-9C, while a disk type water flow limiting orifice is shown in FIGS. 10A-10C. In another implementation, it can be molded directly into one of the rubber water distribution components. In the implementation shown, the orifice is fabricated as part of barbed fitting which allows it be coupled directly to tubing. In another implementation, one side of the barbed water orifice can be inserted directly into the grommet without need for an additional interface fitting.
Fuel Cartridge As shown in further detail in FIGS. 13A, 13B, and 14A, the fuel cartridge 120 is designed for the “water-reactive” class of cartridges. That is, the reactant fuel material 177 in the fuel cartridge 120 undergoes a chemical reaction with water. The chemical reaction generates hydrogen gas, which is combined with oxygen or another oxidizing agent in the fuel cell 110 to generate electricity.
In one example implementation, the fuel cartridge 120 is constructed using a thin-walled metal canister 1426 that includes a water-reactive fuel material 177 (powder) and a plastic top cap 1327. The metal canister 1426 can be sized for convenient handling and use in conjunction with the water feed tray 130. For example, the metal canister 1426 can be circular with a range of diameters, some being from between 40 and 60 mm, such as the 51 mm diameter shown in FIGS. 13A, 13B, and 14A. The canister 1426 can be made with a range of heights, some being from between 10 and 30 mm, such as the 19 mm height shown in FIGS. 13A, 13B, and 14A. The canister 1426 can be made of impact extruded aluminum and can be plated with other materials, such as metals, polymers, or epoxys, for example. A plastic top cap 1327 can be used to seal the canister 1426. Canisters and caps of other materials, such as all plastic, all metal, rigid-walled, flexible-walled, can also be used and can be selected based upon the type of water-reactive fuel material used, whether water or a different solution is used, whether the fuel canister and/or cap is to be re-used.
As shown in FIGS. 15C and 15D, an overmolded face seal gasket 1537 serves to seal two surfaces which are parallel to each other. Often, when injecting into a rubber material, the injecting device can leave a rough surface or extra material at the point of injection 1555. An extra material (called “flash”) can be left at the site where the two tools come together. The overmolded face seal gasket 1537 of the claimed invention is configured to allow the injection point of the over-mold to be on a surface other than the sealing surface. That is, the point of injection 1555 of the rubber is offset from the seal points 1566, 1567 where the cap 1527 and the path of the hydrogen output 1588. During manufacture, the injection rubber first fills the horizontal valley of overmolded face seal 1537 and then flows up to form a flash free point at the hydrogen seal 1566. The result is a smooth hydrogen seal surface. The sealing surfaces include, but are not limited to, sodium silicide cartridge I/O ports and fuel cell I/O ports, including hydrogen output port 1588. The face seal gasket 1537 prevents radial leakage of hydrogen gas or other fluids. The overmolded design provides for a single cap component (as shown in FIG. 15D), which decreases cost.
Returning to FIGS. 13A, 13B, and 14A, in one example implementation, the canister 1426 can be connected to the cap 1327 by a mechanical crimp. Plastic top cap 1327 can be crimped to seal the fuel cartridge 120 using crimping tool 1606 as shown in FIG. 16. Crimping tool 1606 can be used to make a rollover crimp in construction of the fuel cartridge 120 as shown in FIG. 16B. In this example, the fuel cartridge 120 body includes the metal canister 1426 and the cap 1327. By applying pressure through the press crimping tool 1606 directly down onto the canister and cap, the wall of the canister 1426 rolls over the top of the cap 1327. This enables the use of very thin walled fuel cartridges while providing a highly robust cap restraint mechanism. This technique and construction can also readily be fabricated in high volume production using a rapid vertical compression to create the rollover cartridge crimp.
As shown in FIGS. 13A and 13B, alternatively (or in combination), the fuel cartridge 120 can also include a sealing screw 1313 and threaded PEM standoff 1314 combination to secure the cap 1327 to the canister 1426. The screw/standoff combination can be connected inside or outside of the can. The screw/standoff approach allows for reusable caps 1327 and canisters 1426, while crimp connections allow for lower weight, lower cost, and disposability. Of course other types of joining mechanisms and fasteners such as glue, epoxy, welds, bolts, clips, brackets, anchors, and the like can also be used. Fuel cartridge 120 can also include a filtration assembly 1359 that can be used to filter the hydrogen 188 before it is used in the fuel cell 110.
Shown in FIGS. 13A and 13B, the valve between the fuel cartridge 120 and the fuel cell 110 is referred to as the cartridge valve 1328. Another example of a cartridge valve integrally mounted to the cap 1327 is shown in FIGS. 17A-17D. In the implementation shown, the orifice in the plastic cap 1327 provides the core function of a cartridge valve (i.e. hydrogen flow control) in a simple-to-manufacture package. Cartridge valve 1328 can include an o-ring type compression fitting about the orifice, for example, using a compression force of up to approximately 20 N to compress the o-ring at a distance of 1.5 mm.
In some example implementations, the fuel cartridge 120 can have two sealed locations, where one sealing location (cartridge valve 1328) allows hydrogen 188 to pass from the fuel cartridge 120 to the fuel cell 110, and another sealed location (needle valve 1329) allows water 199 to be inserted into the fuel cartridge 120. In FIG. 21A, a perspective view of the needle valve 1329 is shown. Also, in FIG. 21B, a detailed cross sectional view of the needle valve 1329 is shown. The needle valve 1329 can be constructed along the functional lines of a sports ball grommet. As a water sealing device, needle valve 1329 allows water, liquids, or other solutions to be inserted into the canister 1426 via a needle or other penetrating source. Upon removal of the needle or penetrating source, the liquid will not drain or otherwise flow from the fuel cartridge 120. In one or more example implementations, a silicone grommet is used as the needle valve 1329 and is opened with the insertion of the water feed tray needle 682. Upon removal of the fuel cartridge 120 from the water feed tray 130, the water feed tray needle 682 is removed from the fuel cartridge 120, and the silicon grommet self-closes to form the seal.
The needle valve 1329 can be constructed of silicon, or other rubbers, with a number of different hardness specifications and dimensions. For example, the needle valve 1329 shown in FIGS. 13A, 13B, 21A and 21B is a silicon grommet with a 1/16″ inside diameter needle entry point 2158. This would permit a 22 gauge needle to enter the valve 1329. The height and width of the needle valve can also vary based upon the size of the canister 1426, fuel tray 130, water feed tray needle 682 and other components. For example, the needle valve 1329 shown in FIGS. 13A, 13B, 21A and 21B is a silicon grommet with a 5/16″ height, extending 3/16″ outside of the canister 1426. Similarly, the water distribution point 2157 can vary in size and specification as well. Water distribution point 2157 is where a reaction feed tube (not shown in FIGS. 21A and 21B) attaches to deliver water to the reactant fuel material to begin the reaction. Water distribution point 2157 can also vary in size and geometry such that water can travel straight through the needle valve (as shown in FIG. 21A and FIG. 21B) or can pass through at an angle (as shown in FIG. 13A and in FIG. 13D). For example, in FIG. 13D, the needle valve 1329 uses a grommet where the water 199 from the water feed tray 130 travels vertically into the canister while the water comes out of the grommet at a 90 degree angle into the canister 1426. The angled needle valve shown in FIG. 13D facilitates a low-profile canister design.
As shown further in FIG. 23A, for additional fluid isolation, a silicone sheet 2353 can be added on top of the needle valve 1329. Silicone sheet 2353 collects any liquid droplets off the edge of the water feed tray needle (not shown separately in FIG. 23). This additional measure of fluid isolation can serve to protect against liquids having a high pH, which could shed droplets. The water feed tray needle can, at times, have a droplet or a residual spray come out of it. The silicone sheet 2353 structure creates a void 2354 volume for the capture of any liquid upon removal of the water feed tray needle. An illustration of the water feed tray needle 682 being pulled out and stretching a silicone sheet 2353 and creating a void space is shown in FIG. 23B. A bottom view of the silicone sheet 2353 is shown in FIG. 23C. Additionally, a needle valve can be fabricated to perform both functions of the needle valve 1329 and silicone sheet 2353 in a single component.
As shown in FIG. 18A, the reaction feed tube 1883 is inserted inside the fuel cartridge and connected to the water distribution point 2157 to distribute of water 199 throughout the fuel cartridge 120. In one example implementation, silicone is used as the reaction feed tube 1882, and small holes 1884a, 1884b, 1884c are used for water dispersion. Small holes 1884a, 1884b, 1884c in rigid tubing may have a tendency to clog due to the byproducts of the reaction in the fuel cartridge 120. The holes 1884a, 1884b, 1884c can be precision-drilled, molded, or precision punched. In one example implementation, the holes in the silicone reaction feed tube 1883 will self-enlarge around blockages due to the flexibility of the tubing.
In one example implementation shown in FIG. 18B, a T-fitting 1884 can be used to connect the reaction feed tube 1883 to the water distribution point 2157. The T-fitting 1884 allows for rapid hand-assembly of the reaction feed tube 1883 and allows customization of the reaction feed tube and the delivery of the water to the reactant fuel material. As was the case with the reaction feed tube 1883 of FIG. 18A, similar silicone (or other flexible) tubing employing a T-fitting 1884 can utilize a hole or a series of holes to control the uniformity, speed, and amount of water distributed by the reaction feed tube to the reactant fuel material. For example, holes can be fabricated in a wide range of different sizes and locations. The T-fitting 1884 allows for the use of silicone or other flexible tubing without custom molding. The T-fitting 1884 also allows for the tubing to stay in a controlled area. Without a T-fitting, the tubing of the reaction feed tube 1883 has a tendency to spring out towards to the walls of the canister 1426. If water is delivered to the reactant fuel material using this configuration, the water could pool in areas near the canister walls and not reach all of the reactant fuel material. The T-fitting allows for the tubing to be kept off the wall without the need of glue, other mechanical supports, or custom molded components and provides a uniform distribution of water to the reactant fuel material. However, these other supports can be used too.
The fuel cartridge 120 can be segmented such that each time the fuel cell 110 is attached to the water feed tray 130 (or attached to the integrated combination of a water feed tray and a fuel cartridge in those water reactive hydrogen fuel cell power systems where the fuel cartridge is not a separate physical device from water feed tray) water is provided to a different portion of the fuel cartridge, thereby reacting with unspent reactant fuel material. For example, as shown in FIG. 24A and discussed below with regard to the fuel cartridges, one example fuel cartridge 2420 can be divided into a number of sections 2421, 2422, 2423, 2424, 2425, 2426 within which reactant fuel material can be provided. For clarity and brevity, in FIG. 24A six sections 2421, 2422, 2423, 2424, 2425, 2426 are illustrated, but fuel cartridge 2420 can include any number and configurations of sections, such as ten sections for example. The sections can be radially oriented as shown in FIG. 24A with dividing walls 2460 separating each section, or can be oriented in other configurations with which to separate portions of the reactant fuel material. In the example configuration shown in FIG. 24A, fuel cartridge 2420 also includes a rotatable actuator manifold 2450 that is used to select the section of the fuel cartridge to which water is to be delivered. Each time fuel cell 110 is attached to the water feed tray and fuel cartridge combination, rotatable actuator manifold 2450 engages with a needle (such as water feed tray needle 682 as shown in FIG. 6D, for example). Upon attachment, the water feed tray needle (not shown in FIG. 24A) causes the rotatable actuator wheel 2350 to rotate in step such that actuator wheel aperture 2470 rotates to the “next” section of the fuel cartridge. For example, FIG. 24A shows aperture 2470 providing access to section 2424 of the fuel cartridge 2420.
In use, water 199 flows from feed tray 130 through water pathway 535 as shown further in FIG. 6D. Water 199 enters the fuel cartridge 120 via water feed tray needle 682. As further illustrated in FIG. 24A, water is distributed through aperture 2470 to the reactant fuel material present in that section 2424 of the fuel cartridge 2420. After the reaction takes place and the fuel cell 110 is used to provide power to a device, the fuel cell 110 can be removed from the water tray/fuel cartridge combination.
With the sectional fuel cartridge 2420, the water-reactive, hydrogen-fueled power system 100 can be reused multiple times (for example, the number of times can correspond to the number of sections in the fuel cartridge 2420). When subsequently re-using the system 100, the fuel cell 110 is reconnected to the water tray/fuel cartridge combination. Upon re-attachment, water feed tray needle 682 (shown in FIG. 6D) engages the rotatable actuator manifold 2450 which rotates and causes the aperture 2470 to move from section 2424 to section 2425 as further shown in FIG. 24B. By rotating the aperture 2470 to section 2425, water can now be delivered to the reactant fuel material present in that section 2425 of the fuel cartridge 2420. Of course, this process can be repeated multiple times as the fuel cell 110 is reused to charge and/or provide power to a device.
Likewise, alternative techniques for delivering water to different sections of the fuel cartridge can also be used. For example, water delivery can be affected by selecting different water tubes to deliver water from a needle to the individual sections. As shown further in FIG. 25A, the rotatable actuator manifold 2450 can include multiple ports 2571, 2572, 2573 that can be selected, and water 199 from the water feed tray can be directed to different water tubes (not shown separately) and ultimately to different sections of the fuel cartridge. A rotation inducing clip 2585 can be employed to rotate the manifold 2450 to select the appropriate tubes. As shown further in FIG. 25B, the one-way rotation of the clip 2585 imparts a one-way rotation of the manifold 2450 using directional teeth or fins, such as teeth 2586 on the rotation inducing clip 2585 of FIG. 25B. As outlined above, rotation of the manifold can be induced mechanically, electrically, magnetically, or the like, depending upon the environment in which the system is used and the particular application.
As shown in FIGS. 14G AND 14H, in one example implementation a reactant retention screen 1447 can be implemented to prevent both reactant fuel material 177 from moving and/or clumping and to prevent the nucleation of high viscosity silicate bubbles. If the system 100 is operated while the fuel cartridge 120 is lying on its side or is upside down, the water feed tray 130 may not be adding water flow to the reactant fuel material 177. The retention screen 1447 keeps the powder in close proximity within the canister 1426. In one example, a molded retention screen 1447 can be fabricated with a diameter slightly larger than the inner diameter of the wall of the canister 1426. The retention screen 1447 can be pushed on top of the reactant fuel material 177 thereby consolidating the powder near the water distribution point of the fuel cartridge or under the water tubing 1883 (shown in FIGS. 18A and 18B) resulting in a uniform distribution of the reactant fuel material in proximity to the location of the water distribution. This configuration will provide a more uniform reaction than if the reactant fuel material were distributed in a non-uniform fashion throughout the canister 1426.
Additionally, as outlined above, in one example implementation, a water restriction orifice 1886 can be provided between the water distribution point 2157 and the reaction feed tube 1883. In another example, the water restriction orifice can be formed directly in the needle valve 1329 or directly in the reaction feed tube 1883. The water restriction orifice 1886 can be sized to limit the water flow to avoid excess water at start of the reaction or in case of a fuel cartridge breach. In the fuel cartridge breach, no hydrogen back pressure develops to counteract the spring pressure, which results in very high amounts of water delivered to the fuel cartridge, which in turns creates very high levels of hydrogen flow.
In a hydrogen “valve-less” configuration shown here, no traditional valve is used between the fuel cartridge and fuel cell. Hydrogen is generated when the fuel cell 110, fuel cartridge 120, and water feed tray 130 are connected, thereby eliminating the need for such a valve. Rather, as described above, a simple o-ring, face-seal, or other simple seal mechanism between the fuel cartridge and the fuel cell are utilized without the need for a normally closed valve for the storage of gaseous hydrogen. The water-reactive fuel cell cartridge regulatory safety requirements require passing a water immersion test without significant (if any) hydrogen generation. A separator membrane can be used to keep water from back-diffusing through the hydrogen output orifice into the fuel cartridge materials that are water reactive. The cartridge valve is closed to prevent entry of water into the cartridge when it is not connected to the water feed tray and fuel cell.
For example, in one implementation, the hydrogen separator membrane can be heat-staked to the fuel cartridge cap. In one example implementation, the hydrogen separator membrane contains a scrubber to ensure hydrogen purity. As shown in FIGS. 15A and 15B, the cap can include hydrogen pathways (FIG. 15A) or a maze (FIG. 15B) inside the cap to provide additional separation and filtration capabilities. For example, CuO can be used. Additional scrubber materials can also be employed in the pathways depending upon the type and amount of potential contaminants that may be present. The scrubbers and separating membranes can be chosen to ensure that high purity hydrogen gas is delivered to the fuel cell. In one example implementation, a sheet is used between the scrubber and the membrane separator to provide a long path-length over a filter bed.
Fuel cells typically operate on a given pressure where the hydrogen flow rate is determined by the electrical current output. As outlined above and in FIGS. 13A and 13B, the cartridge valve 1328 between the fuel cartridge 120 and the fuel cell 110 is a hydrogen orifice that can serve as a hydrogen flow restriction orifice. That is, a flow-restriction orifice in the top cap can be used to set or regulate the hydrogen flow (pressure) to the fuel cell. The developed hydrogen flow is determined by the hydrogen orifice size and the developed hydrogen pressure, which is determined by the delivered water pressure (to the reactant fuel material). In the claimed invention, the fuel cell dynamically adjusts to the developed hydrogen flow. The fuel cell increases fuel consumption if hydrogen is available and decreases consumption if not available by charging or discharging a battery (in the fuel cell) at a constant load. The cartridge valve (hydrogen orifice) and the pressure developed by the water feed system spring are used to set the hydrogen flow to an optimal flow range which enables the fuel cell to operate at a predictable current. In this fashion, the hydrogen fuel cell of the claimed invention is analogous to an electrical current-source, as opposed to previous systems where hydrogen fuel cells were typically analogous to electrical voltage sources. Alternatively, the hydrogen orifice can be used to simply set a maximum flow and the cartridge will self-regulate flow below the maximum level as determined by the developed pressure and orifice size. If a fuel cell consumes less than the maximum level and contains a valve to build up internal fuel cell pressure (as is common with fuel cell systems), the fuel cartridge will self regulate and maintain a nominal constant pressure and only generate the amount of hydrogen required by the fuel cell.
As outlined above, the fuel cartridge can utilize sodium silicide powder as the reactant fuel material. For example, a 30 g fuel cartridge can include 4 g of sodium silicide powder. Approximately 10 ml of water is mixed with this energy-carrying reactant fuel material to produce approximately 4 liters of hydrogen gas, resulting in an energy output from the fuel cell of approximately 4 watt hours. The fuel cartridge is water-proof, has a minimum shelf life of two years, can be stored at temperatures of up to 70° C., and can be used in operating temperatures between approximately 0° C. to 40° C. to generate hydrogen gas to be used in fuel cell 110.
Fuel Cell As outlined above, the claimed system incorporates a water-reactive fuel cell that utilizes a reactant fuel material, such as sodium silicide, for example, and water to generate hydrogen. One example fuel cell in accordance with the claimed invention includes a 4 Polymer Electrolyte Membrane (PEM) 1000 mAh cell fuel cell stack rated for a 5V, 500 mA input and a 5V, 1000 mA output. One example fuel cell in accordance with the claimed invention includes a Li-ion 1600 mAh internal buffer and utilizes a micro USB charging input port and a USB-A charging output port.
An example fuel cell in accordance with the claimed invention has a rated input (micro USB charging of the internal battery) of 2.5 W and a rated total output of 2.5 W (fuel cell mode) and 5.0 W (internal buffer/battery mode). One example fuel cell in accordance with the claimed invention includes an internal buffer (battery) capacity of 5.9 Wh (1600 mAh, 3.7 V). One example fuel cell in accordance with the claimed invention is compact and portable with approximate dimensions of 66 mm (width)×128 mm (length)×42 mm (height) and weighs approximately 175 g (without water feed tray) and approximately 240 g (with the water feed tray).
Having thus described the basic concept of the invention, it will be rather apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. In addition to the embodiments and implementations described above, the invention also relates to the individual components and methods, as well as various combinations and subcombinations within them. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and scope of the invention. Additionally, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefore, is not intended to limit the claimed processes to any order except as can be specified in the claims. Accordingly, the invention is limited only by the following claims and equivalents thereto.
