Orientation independent fuel reservoir containing liquid fuel

[0001] The instant application claims the benefit of U.S. Provisional Patent Application Nos. 60/460,406 (filed on Apr. 7, 2003) and 60/411,353 (filed on Sep. 18, 2002), the disclosures of which are incorporated by reference. The instant application is also a continuation-in-part application of U.S. Non-Provisional patent application Ser. No. 10/329,776, filed on Dec. 27, 2002, the disclosure of which is also herein incorporated by reference.

[0002] This invention relates to liquid fuel cells in which the liquid fuel is directly oxidized at the anode. In particular, it relates to the reservoir for holding and metering or delivering the liquid fuel to the anode of a liquid fuel cell. This invention also relates to liquid fuel feed systems for micro fuel cell reformers.

[0003] Electrochemical fuel cells convert reactants, namely fuel and oxidants, to generate electric power and reaction products. Electrochemical fuel cells generally employ an electrolyte disposed between two electrodes (an anode and a cathode). An electrocatalyst is needed to induce the desired electrochemical reactions at the electrodes. Liquid feed solid polymer fuel cells operate in a temperature range of from about 0 C. to the boiling point of the fuel, i.e., for methanol about 65 C., and are particularly preferred for portable applications. Solid polymer fuel cells include a membrane electrode assembly (MEA), which comprises a solid polymer electrolyte or proton-exchange membrane, sometimes abbreviated PEM, disposed between two electrode layers. Flow field plates for directing the reactants across one surface of each electrode are generally disposed on each side of the membrane electrode assembly. There is typically a backing layer (or gas diffusion layer) between the flow field plate and the MEA.

[0004] A broad range of reactants have been contemplated for use in solid polymer fuel cells, and such reactants may be delivered in gaseous or liquid streams. The oxidant stream may be substantially pure oxygen gas, but preferably a dilute oxygen stream such as found in air, is used. The fuel stream may be substantially pure hydrogen gas, or a liquid organic fuel mixture. A fuel cell operating with a liquid fuel stream wherein the fuel is reacted electrochemically at the anode (directly oxidized) is known as a direct liquid feed fuel cell.

[0005] A direct methanol fuel cell (DMFC) is one type of direct liquid feed fuel cell in which the fuel (liquid methanol) is directly oxidized at the anode. The following reactions occur:

[0006] The hydrogen ions (H) pass through the membrane and combine with oxygen and electrons on the cathode side producing water. Electrons (e) cannot pass through the membrane, and therefore are collected and flow from the anode to the cathode through an external circuit driving an electric load that consumes the power generated by the cell. The products of the reactions at the anode and cathode are carbon dioxide (CO₂) and water (H₂O), respectively. The open circuit voltage from a single cell is about 0.7 to 1 volt. Several direct methanol fuel cells are connected in series to obtain greater voltage.

[0007] Other liquid fuels may be used in direct liquid fuel cells besides methanole.g., other simple alcohols, such as ethanol or ethylene glycol, or dimethoxymethane, trimethoxymethane, hydrazine and formic acid. Further, the oxidant may be provided in the form of an organic fluid having a high oxygen concentrationi.e., a hydrogen peroxide solution.

[0008] A direct methanol fuel cell may be operated on aqueous methanol vapor, but most commonly a liquid feed of a diluted aqueous methanol fuel mixture is used. It is important to maintain separation between the anode and the cathode to prevent fuel from directly contacting the cathode and oxidizing thereon (called cross-over). Cross-over results in a short circuit in the cell since the electrons resulting from the oxidation reaction do not follow the current path between the electrodes. To reduce the potential for cross-over of methanol fuel from the anode to the cathode side through the MEA, very dilute aqueous mixtures of methanol (for example, about 5 per cent of methanol in water, wherein the methanol concentration is expressed in methanol weight as percent of the total weight of the aqueous mixture) are typically used as the fuel streams in liquid feed DMFCs.

[0009] The proton exchange membrane (PEM) is a solid, organic polymer, usually polyperfluorosulfonic acid, that comprises the inner core of the membrane electrode assembly (MEA). Commercially available polyperfluorosulfonic acids for use as PEM are sold by E.I. DuPont de Nemours & Company under the trademark NAFION. Alternatively, composites of porous polymeric membranes impregnated with perfluoro ion exchange polymers, such as offered by W.L. Gore & Associates, Inc., can be used as the proton exchange membranes. The PEM must be hydrated to function properly as a proton (hydrogen ion) exchange membrane and as an electrolyte.

[0010] For efficient function of the fuel cell, the liquid fuel should be controllably metered or delivered to the anode side. The problem is particularly acute for fuel cells intended to be used in portable applications, such as in consumer electronics including cell phones, where the fuel cell orientation with respect to gravitational forces will vary. Traditional fuel tanks with an outlet at the bottom of a reservoir, and which rely on gravity feed, will cease to deliver fuel when the tank orientation changes. In addition, dipping tube delivery of a liquid fuel within a reservoir varies depending upon the orientation of the tube within the reservoir and the amount of fuel remaining in the reservoir. Accordingly, to facilitate use of liquid fuel cells in portable electronic devices, a liquid fuel reservoir that controllably holds and delivers fuel to a liquid fuel cell, regardless of orientation, is desired.

[0011] A liquid fuel reservoir containing a wicking member, such as a urethane foam, is disclosed in co-pending U.S. Non-Provisional patent application Ser. No. 10/183,943, filed Jun. 28, 2002.

[0012] The first aspect of the invention relates to a fuel reservoir for a liquid fuel cell or microreformer. This fuel reservoir has a container having walls that define a volume for holding a liquid fuel for the liquid fuel cell or microreformer, wherein the container has an outlet passageway through one of the walls for the exit of the liquid fuel to a location exterior to the container. Preferably, the outlet passageway contains no wicking material inside, especially in the portion of the outlet passageway that penetrates one of the walls of the container. The container may have a regular or irregular cross-sectional shape depending upon the application. Examples of regular cross-sectional shapes are triangular, quadrilateral (e.g. rectangular, square, parallelogram, and trapezoid which is a quadrilateral shape having two parallel sides), pentagon, circular, oval, and elliptic shapes. The walls of the container can be made of a rigid or flexible material. When the container walls are made of a flexible material, the walls are collapsible allowing for easier stowage of an empty liquid fuel reservoir and allowing a liquid fuel reservoir filled with liquid fuel to better adapt to a space inside a fuel cell in which the reservoir may be installed. A wicking structure is disposed within the volume of the container, wherein the wicking structure comprises a wicking structure material which can wick the liquid fuel and wherein the liquid fuel wicked into the wicking structure material can subsequently be discharged out of or released from the wicking structure material. A retainer is preferably provided to hold the wicking structure in a desired orientation within the container volume. When the liquid fuel reservoir contains the liquid fuel, at least a portion of the liquid fuel wicks into the wicking structure material. Such liquid fuel wicked into the wicking structure material subsequently may be delivered or metered out of the wicking structure material for use in a fuel cell or microreformer via the outlet passageway which communicates with the wicking structure. The liquid fuel may be metered or delivered from the wicking structure material to the fuel cell with a liquid delivery means, such as a pump, in fluid communication with the outlet passageway. The liquid fuel reservoir also may include an inlet through the container, said inlet optionally having a one-way valve to permit gas or liquid flow into the volume of the container and prevent the backflow of any fluid out of the container.

[0013] After the liquid fuel in the reservoir has been discharged, partially or completely, the outlet passageway or inlet may be used to introduce replenishing liquid fuel into the volume of the container to replace any spent liquid fuel making the fuel reservoir recyclable. Optionally, the container has a sealable cap comprising a membrane through which replenishing liquid fuel can be introduced into the volume of the container upon puncture, e.g. by a needle of a syringe, of the membrane. The membrane should be made of a material resistant to the liquid fuel and puncturable by the needle, which material can reseal after the needle is withdrawn.

[0014] The wicking structure material extends to or near at least one extremity of the container remote from the outlet passageway, so as to permit liquid fuel located at such extremity to be wicked through the wicking structure material to the outlet passageway. Preferably, the wicking structure material extends to or near all extremities of the container remote from the outlet passageway, so that all the liquid fuel in the volume maintains, regardless of the orientation of the liquid fuel reservoir and the stage of liquid fuel depletion, fluid communication with the outlet passageway of the container at least via capillarity.

[0015] In a preferred embodiment of the liquid fuel reservoir, the volume of the container has a longest dimension. The wicking structure material has a free rise wick height of at least one half of the container volume's longest dimension (more preferably at least the container volume's longest dimension).

[0016] The liquid fuel reservoir of the invention can contain a liquid fuel for liquid fuel cells. The liquid fuel can contain or be an aqueous mixture of a simple alcohol, such as ethanol, ethylene glycol, or preferably methanol. The liquid fuel can also be a liquid containing dimethoxymethane, trimethoxymethane, hydrazine or formic acid. To increase the safety when the liquid fuel reservoir is used, the liquid fuel can further include an ingestion deterrent and/or flame brightening additive. Examples of the ingestion deterrent are an additive, such as Bitrex (denatonium benzoate), that adds a bad flavor, or an additive, such as syrup of ipecac, that can induce vomiting upon ingestion. Flame brighteners are typically salts known in the art.

[0017] When the ingestion deterrent and/or flame brightening additive is included in the liquid fuel, the liquid fuel stored in the liquid fuel reservoir is preferably exposed to an impurities scavenger, which comprises one scavenging substance or a mixture of scavenging substances, in order to remove the ingestion deterrent and/or flame brightening additive before being fed to the liquid fuel cell or micro reformer. However, even if the ingestion deterrent and/or flame brightening additive is not included in the liquid fuel, the liquid fuel stored in the liquid fuel reservoir may preferably also be exposed to the impurities scavenger before being fed to the liquid fuel cell or micro reformer in order to remove any impurities in the liquid fuel that may poison the components, e.g. the catalysts, electrodes or membrane, in the liquid fuel cell or micro reformer. The scavenging substance can be an impurities absorbent or adsorbent, such as activated carbon, e.g. activated charcoal, amorphous carbon, e.g. carbon black, graphite powders having a high surface area, expanded graphite, silica, silicate, e.g. aluminosilicate (e.g. Fullers Earth, CAS 8031-18-3) and diatomaceous earth, exchange resins, zeolites, molecular sieves or filter agents, e.g. Celatom FW80, CAS 68855-54-9, capable of removing the ingestion deterrent, flame brightening additive and/or the impurities in the liquid fuel. Preferably, the scavenging substance is activated carbon. The scavenging substance can be in the form of powders or granules either in a loosen state or supported on a substructure. The particle size of the scavenging substance can be from about 1 nm to about 1 cm, preferably 10 m to 5 mm, and more preferably 50 m to 1 mm. The typical surface area of the scavenging substance is about 50 m²/g.

[0018] The impurities scavenger can be inside (a) at least one porous internal compartment of the liquid fuel reservoir, (b) the outlet passageway of the liquid fuel reservoir, and/or (c) a filter cartridge having an inlet port and outlet port, wherein the inlet port is attached to the exit of the outlet passageway, and the outlet port can be connected to a liquid fuel cell or micro reformer. The at least one porous internal compartment is inside the container of the liquid fuel reservoir, wherein the porous internal compartment comprises at least one porous wall enclosing an internal volume holding the impurities scavenger. The at least one porous wall is made of a porous material, e.g. filter paper, a fabric of woven fibers, or a screen, that can allow the liquid fuel to permeate. Preferably, all the walls of the porous internal compartment comprise the porous material, e.g. the porous internal compartment can be a porous pouch.

[0019] In some of the embodiments of the liquid fuel reservoir of the invention, the container contains at least one porous internal compartment holding an impurities scavenger. The porous internal compartment can be of any regular, e.g. rectangular, square or oval, or irregular shape, e.g. a pouch. The porous internal compartment, preferably, is of a generally flat shape of a rectangle, square or oval. Preferably, the at least one porous internal compartment is disposed near, or touching, at least a portion of the internal surface of at least one wall of the container, wherein more preferably the portion is free of the wicking structure. Even more preferably, the at least one porous internal compartment has corners that proximate the corners of the at least one wall of the container, and/or has edges that proximate the edges of the at least one wall of the container. Much more preferably, the container contains two porous internal compartments each disposed near, or touching, at least one portion of the internal surface of one of two opposing walls of the container, wherein most preferably the portion is free of the wicking structure. Even much more preferably, the corners and/or edges of each of the two porous internal compartments proximate the corners and/or edges, respectively, of the corresponding opposing walls.

[0020] In some of the embodiments of the liquid fuel reservoir of the invention having a liquid fuel containing an ingestion deterrent, when the liquid fuel reservoir is of a disposable variety, the liquid fuel reservoir and the filter cartridge containing the impurities scavenger can be separate entities, so that if the liquid fuel in the reservoir is consumed, the ingestion deterrent would still be effective. In some of the embodiments of the liquid fuel reservoir of the invention having a liquid fuel containing an ingestion deterrent, when the liquid fuel reservoir is used to supply liquid fuel to a liquid fuel cell, the liquid fuel reservoir can be in fluidic communication with the filter cartridge containing the impurities scavenger, so that the impurities scavenger can render the liquid fuel acceptable to the liquid fuel cell. The filter cartridge can be permanently affixed to the liquid fuel reservoir, assuring that any leaked liquid fuel would be treated. The liquid fuel reservoir and the filter cartridge can be supplied as separate entities, which can be assembled together by the user and installed into a liquid fuel cell. The filter cartridge can be designed to specifically not mount onto the liquid fuel reservoir, but mount in separate locations of the liquid fuel cell thereby preventing the user from assembling the two units and having access to untreated fuel. The liquid fuel can be driven from the liquid fuel reservoir by a pressurizing mechanism or drawn from the liquid fuel reservoir by a pump. The impurities scavenger can be replaced as needed to assure a clean liquid fuel supply to the liquid fuel cell.

[0021] Another aspect of the invention provides a package for delivering a fuel to a liquid fuel cell having a container defining a volume for holding a liquid fuel for a liquid fuel cell. A wicking structure is held within the container volume and at least a portion of the liquid fuel wicks into the wicking structure. A retainer holds the wicking structure in a desired orientation within the container volume. An outlet passageway through the container communicates with the wicking structure in the container. Once a liquid fuel is introduced into the volume of the container, such liquid fuel may be metered or delivered from the wicking structure and through the outlet passageway with a pump or other metering or liquid delivery means separate from the fuel wicking structure in the container. Preferably, the package is provided with an inlet optionally having a one-way valve to permit gas or liquid flow into the volume of the container but preventing undesired release of gas and fuel from the container. The structures of the container, retainer and wicking structure preferably are the same as those described with reference to the liquid fuel reservoir of the first aspect of the invention disclosed herein.

[0022] A further aspect of the invention is a method of dispensing a liquid fuel using a fuel reservoir of the invention. The method includes the steps of: (a) providing a container defining a volume having at least one extremity, said volume holding the liquid fuel; (b) providing a wicking structure within the volume, the wicking structure extending to the at least one extremity, wherein the wicking structure comprises a wicking structure material into which the liquid fuel can wick and from which the liquid fuel can be discharged; (c) wicking at least a portion of the liquid fuel into the wicking structure; and (d) delivering the liquid fuel from the wicking structure to a location exterior to the container through an outlet passageway in the container that communicates with the wicking structure in the container. In a preferred embodiment of the method, the wicking structure in step (b) is held by a retainer in a desired orientation within the volume of the container. Step (d) is preferably carried out by pumping the liquid fuel out of the wicking structure to the exterior location. A gas, such as air or nitrogen, may be introduced into an inlet formed through the container. Preferably, the inlet has a one-way valve to permit gas flow into the container volume without allowing any gas or liquid to leave the container.

[0023] The method of dispensing a liquid fuel has a primary application for dispensing liquid fuels, such as simple alcohols, e.g. methanol, ethanol, ethylene glycol, or mixtures thereof, dimethoxymethane, trimethoxymethane, formic acid, hydrazine and hydrogen peroxide, for use in liquid fuel cell applications. The method of dispensing the liquid fuel also has application for the delivery of fuel to microreformers, which fuels also include hydrocarbons, diesel fuel, gasoline, jet fuel, higher molecular weight alcohols and similar fuels. The structures of the container, retainer and wicking structure preferably are the same as those described with reference to the liquid fuel reservoir of the first aspect of the invention disclosed herein.

[0024] In yet another aspect of the invention, a method of assembling a fuel cartridge for a liquid fuel cell includes the following steps: (a) providing a container having a proximal end and a distal end and defining a volume for holding a liquid fuel for a liquid fuel cell; (b) providing a cap to seal the distal end of the container; (c) providing a wicking structure within the volume and into which at least a portion of the liquid fuel wicks and from which said liquid fuel subsequently may be delivered or metered; (d) providing a retainer to hold the wicking structure in a desired orientation within the container volume; (e) mounting the wicking structure over at least a portion of the retainer; (f) attaching the retainer to the cap; and (g) slidably inserting the wicking structure and retainer into the volume of the container while inserting the cap on the distal end of the container. Once the fuel cartridge has been assembled, it may be filled with a liquid fuel, preferably liquid fuels intended for use in liquid fuel cell applications, such as simple alcohols, e.g. methanol, ethanol, ethylene glycol or mixtures thereof, dimethoxymethane, trimethoxymethane, formic acid, hydrazine and hydrogen peroxide, or liquid fuels intended for reformers, such as hydrocarbons, diesel fuel, gasoline, jet fuel, and higher molecular weight alcohols. Preferably, the liquid fuel is introduced into the container through the vent, outlet passageway, or a passageway formed through a wall of the container, such as the proximal end or a side wall. The structures of the container, retainer and wicking structure preferably are the same as those described with reference to the liquid fuel reservoir of the first aspect of the invention disclosed herein.

[0025] FIG. 1 is a schematic diagram of a liquid fuel delivery system used with a fuel cell to power a fuel cell driven portable electronic device such as a cellular telephone, wherein the liquid fuel delivery system comprises a liquid fuel reservoir of the invention;

[0026] FIG. 2 is an exploded top plan view of the liquid fuel reservoir having a container with a generally rectangular shape shown in FIG. 1 with portions of the drawing partially broken away to show certain structural components;

[0027] FIG. 3 is a top plan view of the assembled liquid fuel reservoir shown in FIG. 2;

[0028] FIG. 4 is a right end view partially in cross-section taken along line 4-4 of FIG. 3;

[0029] FIG. 5 is a longitudinal cross-sectional view taken along line 5-5 of FIG. 3;

[0030] FIG. 6 is left end elevational view partially broken away of an alternative liquid fuel reservoir having a housing with a generally cylindrical shape;

[0031] FIG. 7 is a front elevational view partially broken away of the fuel reservoir shown in FIG. 6;

[0032] FIG. 8 is a top plan view partially broken away of still another alternative liquid fuel reservoir having a housing with a generally cubic shape;

[0033] FIG. 9 is a front elevational view partially broken away of the liquid fuel reservoir of FIG. 8;

[0034] FIG. 10 is a top plan view partially broken away of a further liquid fuel reservoir having a housing with a generally cubic shape with an alternative configuration of wicking material;

[0035] FIG. 11 is a front elevational view partially broken away of the liquid fuel reservoir of FIG. 10;

[0036] FIG. 12 is a top plan view of another alternative liquid fuel reservoir having a housing with a generally rectangular cross-sectional shape with an alternative configuration of wicking material, inlet and outlet tubes, and with portions of the drawing partially broken away to show certain structural components;

[0037] FIG. 13 is a side elevational view of yet another alternative liquid fuel reservoir opened at one end, and having an alternative configuration of wicking material, inlet and outlet tubes;

[0038] FIG. 14 is a top plan view of still another alternative liquid fuel reservoir having an alternative configuration of wicking material, inlet and outlet tubes, and with portions of the drawing partially broken away to show certain structural components;

[0039] FIG. 15 is a perspective view of a wicking structure defining a hollow core and having perforations therethrough;

[0040] FIG. 16 is a top plan view of the surface of a wicking material having slits formed therein;

[0041] FIG. 17 is a top plan view of a wicking material having expanded slits formed therein;

[0042] FIG. 18 is a schematic diagram of a liquid fuel reservoir viewed from the front with a wicking structure having the external volume, as defined below, minimized;

[0043] FIG. 19 is a schematic diagram of the liquid fuel reservoir of FIG. 18 presented from a perspective view;

[0044] FIG. 20 is a schematic diagram of a liquid fuel reservoir viewed from the front with an alternative wicking structure having the external volume minimized;

[0045] FIG. 21 is a schematic diagram of a liquid fuel reservoir similar to the reservoir of FIG. 20 viewed from the front with a wicking structure having the external volume minimized, wherein an outlet passageway is placed at a different location;

[0046] FIG. 22 is a schematic diagram of a liquid fuel reservoir viewed from the front with an alternative wicking structure having the external volume minimized;

[0047] FIG. 23 is a schematic diagram of a liquid fuel reservoir similar to the reservoir of FIG. 22 viewed from the front with a wicking structure having the external volume minimized, wherein an outlet passageway is placed at a different location;

[0048] FIG. 24 is a schematic diagram of a liquid fuel reservoir viewed from the front with an alternative wicking structure having the external volume minimized;

[0049] FIG. 25 is a schematic diagram of a liquid fuel reservoir similar to the reservoir of FIG. 24 viewed from the front with a wicking structure having the external volume minimized, wherein an outlet passageway is placed at a different location;

[0050] FIG. 26 is a schematic diagram of a liquid fuel reservoir viewed from the front with an alternative wicking structure having the external volume minimized;

[0051] FIG. 27 is a schematic diagram of a liquid fuel reservoir similar to the reservoir of FIG. 26 viewed from the front with a wicking structure having the external volume minimized, wherein an outlet passageway is placed at a different location;

[0052] FIG. 28 is a schematic diagram of a liquid fuel reservoir viewed from the front with an alternative wicking structure having the external volume minimized;

[0053] FIG. 29 is a schematic diagram of a liquid fuel reservoir viewed from the front with an alternative wicking structure having the external volume minimized;

[0054] FIG. 30 is a schematic diagram of a liquid fuel reservoir similar to the reservoir of FIG. 29 viewed from the front with a wicking structure having the external volume minimized, wherein an outlet passageway is placed at a different location;

[0055] FIG. 31 is a schematic diagram of a liquid fuel reservoir viewed from the front with an alternative wicking structure having the external volume minimized;

[0056] FIG. 32 is a schematic diagram of a liquid fuel reservoir similar to the reservoir of FIG. 31 viewed from the front with a wicking structure having the external volume minimized, wherein an outlet passageway is placed at a different location;

[0057] FIG. 33 is a schematic diagram of a recyclable or rechargeable liquid fuel reservoir having a sealable, detachable cap containing a membrane;

[0058] FIG. 34 is a schematic diagram of another recyclable or rechargeable liquid fuel reservoir having an outlet passageway containing a valve;

[0059] FIG. 35 is a schematic diagram of an alternative recyclable or rechargeable liquid fuel reservoir having a detachable cap at the end of an outlet passageway;

[0060] FIG. 36 is a schematic diagram of a liquid fuel reservoir similar to the reservoir of FIG. 18 viewed from the front with a wicking structure having the external volume minimized, wherein an outlet passageway is placed at a different location;

[0061] FIG. 37 is a schematic diagram of another liquid fuel reservoir similar to the reservoir of FIG. 18 viewed from the front with a wicking structure having the external volume minimized, wherein an outlet passageway is placed at a different location;

[0062] FIG. 38 is a perspective view of another liquid fuel reservoir according to the invention shown schematically with an alternative wicking structure having the external volume minimized;

[0063] FIG. 39 is a perspective view of another liquid fuel reservoir according to the invention shown schematically with an alternative wicking structure having the external volume minimized; and

[0064] FIG. 40 is a perspective view of another liquid fuel reservoir according to the invention shown schematically with an alternative wicking structure having the external volume minimized.

[0065] FIG. 41 is a schematic vertical cross-sectional view of a liquid fuel reservoir according to the invention.

[0066] FIG. 42 is a perspective view of the liquid fuel reservoir of FIG. 41, wherein the liquid fuel reservoir is in the shape of a cylinder.

[0067] FIG. 43 is a schematic vertical cross-sectional view of one of the embodiments the liquid fuel reservoir of FIG. 18 having at least one porous internal compartment.

[0068] FIG. 44 is a perspective view of the liquid fuel reservoir of FIG. 43.

[0069] FIG. 45 is a schematic horizontal cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 43 along line A-A, wherein the reservoir has one porous internal compartment.

[0070] FIG. 46 is a schematic horizontal cross-sectional view of another embodiment of the liquid fuel reservoir of FIG. 43 along line A-A, wherein the reservoir has two porous internal compartments.

[0071] FIG. 47 is a schematic horizontal cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 43 along line B-B, wherein the reservoir has two porous internal compartments.

[0072] FIG. 48 is a schematic horizontal cross-sectional view of another embodiment of the liquid fuel reservoir of FIG. 43 along line B-B, wherein the reservoir has two porous internal compartments interconnected with a third porous internal compartment. Optionally, the three porous internal compartments can be replaced with one porous internal compartment having a cross section shaped like an alphabet letter, U, i.e. the three porous internal compartments can merge.

[0073] FIG. 49 is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 18.

[0074] FIG. 50 is a perspective view of the reservoir of FIG. 49.

[0075] FIG. 51 is a schematic horizontal cross-sectional view of the reservoir of FIG. 49 along line A-A.

[0076] FIG. 52 is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 20 having at least one porous internal compartment.

[0077] FIG. 53 is a schematic horizontal cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 52 along line A-A.

[0078] FIG. 54 is a schematic horizontal cross-sectional view of another embodiment of the liquid fuel reservoir of FIG. 52 along line A-A.

[0079] FIG. 55 is a schematic horizontal cross-sectional view of the liquid fuel reservoir of FIG. 52 along line B-B.

[0080] FIG. 56 is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 24 having two porous internal compartments.

[0081] FIG. 57 is a schematic perspective view of one of the embodiments of the liquid fuel reservoir of FIG. 40 having two porous internal compartments.

[0082] FIG. 58 is a schematic horizontal cross-sectional view of the liquid fuel reservoir of FIG. 57 along line A-A.

[0083] FIG. 59 is a schematic horizontal cross-sectional view of the liquid fuel reservoir of FIG. 57 along line B-B.

[0084] FIG. 60 is a schematic horizontal cross-sectional view of the liquid fuel reservoir of FIG. 57 along line C-C.

[0085] FIG. 61 is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 41 having a porous internal compartment.

[0086] FIG. 62 is a schematic perspective view of the liquid fuel reservoir of FIG. 61.

[0087] FIG. 63 is a schematic perspective view of one of the embodiments of the liquid fuel reservoir of FIG. 38 having two porous internal compartments.

[0088] FIG. 64A is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 18 containing an impurities scavenger in an outlet passageway.

[0089] FIG. 64B is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 18 containing an impurities scavenger in a filter cartridge connected to an outlet passageway.

[0090] FIG. 65 is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 20 containing an impurities scavenger in an outlet passageway.

[0091] FIG. 66 is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 21 containing an impurities scavenger in an outlet passageway.

[0092] FIG. 67 is a schematic vertical cross-sectional view of one of the embodiments of the liquid fuel reservoir of FIG. 41 containing an impurities scavenger in an outlet passageway.

[0093] In the invention, wicking means wicking by capillary action, i.e. moving a liquid by capillary forces. A wicking structure is a structure capable of wicking a liquid by capillary action, which liquid may be later released from the structure. The wicking structure comprises a wicking material capable of wicking the liquid by capillary action.

[0094] The wicking structure can be a porous member made of one or more polymers resistant to the liquid fuel. The wicking structure material can be selected from foams, bundled fibers, matted fibers, needled fibers, woven or nonwoven fibers, Porex and Porex like polymers, porous polymers or inorganic porous materials that can wick the liquid fuel. The wicking structure material preferably is selected from the group consisting of foams, bundled fibers, woven or nonwoven fibers, Porex and porous polymers made by pressing polymer beads. More preferably, the wicking structure material is selected from polyurethane foams (preferably felted polyurethane foams, reticulated polyurethane foams, or felted reticulated polyurethane foams), melamine foams, polyvinyl alcohol foams, or nonwoven felts, woven fibers or bundles of fibers made of polyamide such as nylon, polyethylene, polypropylene, polyester such as polyethylene terephthalate, cellulose, modified cellulose such as Rayon, polyacrylonitrile, and mixtures thereof that can wick the liquid fuel. Certain inorganic porous materials, such as sintered inorganic powders of silica or alumina, can also be used as the wicking structure material. Most preferably, the wicking structure material is a polyurethane foam, e.g. felted polyurethane foam, reticulated polyurethane foam, or felted reticulated polyurethane foam.

[0095] The wicking structure material is preferably a polyurethane foam having a density in the range of about 0.5 to about 45 pounds per cubic foot, more preferably about 0.5 to about 25 pounds per cubic foot, even more preferably about 0.5 to about 15 pounds per cubic foot, most preferably about 0.5 to about 10 pounds per cubic foot, and pore sizes in the range of about 10 to about 200 pores per linear inch, preferably about 40 to about 200 pores per linear inch, and most preferably about 75 to about 200 pores per linear inch.

[0096] If a felted polyurethane foam, e.g. a felted reticulated polyurethane foam, is selected as the wicking structure material, such foam preferably should have a density in the range of about 1.5 to about 60 pounds per cubic foot and a compression ratio in the range of about 1.1 to about 30, more preferably a density in the range of about 3 to about 40 pounds per cubic foot and a compression ratio in the range of about 1.5 to about 20, and most preferably a density in the range of about 3 to about 10 pounds per cubic foot and a compression ratio in the range of about 3 to about 30. Felted foams of greater compression, however, may be used as the wicking structure materials.

[0097] A felted foam is produced by applying heat and pressure sufficient to compress the foam to a fraction of its original thickness. For a compression ratio of 30, the foam is permanently compressed to {fraction (1/30)} of its original thickness. For a compression ratio of 2, the foam is permanently compressed to of its original thickness. Typically, to create a felted foam, the foam is compressed for from 5 to 60 minutes and heated to temperatures from 350 F. to 400 F. During the felting process, the cellular polymer strand network is crushed to a more unidirectional state, where the strands are oriented more in parallel. This is sometimes called an anisotropic cell structure.

[0098] A reticulated foam is produced by removing the cell windows from the cellular polymer structure, leaving a network of strands and thereby increasing the fluid permeability of the resulting reticulated foam. Foams may be reticulated by in situ, chemical or thermal methods known to those of skill in foam production.

[0099] In the liquid fuel reservoir of the invention, the volume effectively occupied by the wicking structure is preferably minimized. One of the ways of minimizing the volume effectively occupied by the wicking structure is to minimize the external volume of the wicking structure by providing a wicking structure that extends to the extreme parts of the volume within the container, with the central portion of the volume within the container being substantially devoid of the wicking structure material. The central portion of the volume within the container can be made substantially devoid of the wicking structure material by making the wicking structure with no or only a minimal amount of wicking structure material in the central portion of the volume within the container. The central portion of the volume within the container is the inner 70%, preferably 80%, more preferably 90%, most preferably 95%, of the volume within the container. Alternatively, the central portion of the volume within the container can be made substantially devoid of the wicking structure material by perforating the wicking structure material. Preferably, the wicking structure material is perforated except in portions of the wicking structure material proximate the walls of the container or except a portion of the wicking structure material in a zone extending from the external surface of the wicking structure adjacent to a wall of the container to a depth of 20% (preferably 10%, and more preferably 5%) of the thickness of the wicking structure at that region, wherein the thickness of the wicking structure at that region is the length of a first imaginary line perpendicular to a second imaginary line tangential to the external surface of the wicking structure at that region, which first imaginary line starts at the external surface, extends through the wicking structure material and ends at where the first imaginary line meets an external surface on the opposite side of the wicking structure. When the wicking structure material is perforated, at least a part of the wicking structure material is removed, and consequently the size of the perforation is larger than the nominal size of the pores in the wicking structure material.

[0100] One of the ways of minimizing the volume effectively occupied by the wicking structure is to perforate the wicking structure material. The size of the perforation is larger than the nominal size of the pores in the wicking structure material.

[0101] By minimizing the amount of the wicking structure material (either by perforating the wicking structure material or by making the central portion of the volume within the container substantially devoid of the wicking structure material), the amount of the liquid fuel that the liquid reservoir can deliver can be maximized because the amount of the liquid fuel that the liquid fuel reservoir can hold can be increased and the amount of the liquid fuel remaining in the wicking structure after all the deliverable liquid fuel is discharged from the liquid reservoir can be decreased. In this preferred embodiment of the liquid fuel reservoir, the volume within the container can have a rectangular or square cross section having eight corners and a square or rectangular shape viewed from the top, and the wicking structure is disposed at least at or proximate the eight corners. For instance, the wicking structure can have a configuration of a square or rectangular sheet with a plurality of perforations, a square or rectangular rim, or a configuration shaped like an alphabet letter E, H, K, M, N, or X. The configuration shaped like the alphabet letter H includes a configuration shaped like an uppercase alphabet letter I because the alphabet letter H is equivalent to the uppercase alphabet letter I turned 90. Similarly, the configuration shaped like the alphabet letter N includes a configuration shaped like an alphabet letter Z. Alternatively, the container can have a curved wall so that the volume within the container can have a round or oval cross section when viewed from above, wherein the wicking structure can be disposed at least as a circular or oval ring along the curved edge of the volume within the container.

[0102] Within the scope of the invention, one of the ways of minimizing the external volume of the wicking structure in a liquid fuel reservoir is to have the wicking structure comprising a sheet or layer of the wicking structure material disposed adjacent to all, or all but one, of the lateral walls of the container. In some of the embodiments of the liquid fuel reservoir within this aspect of the invention, the liquid fuel reservoir comprises

[0103] (a) a container having 5, 6, 7, 8, 9 or 10 walls: a first and second end walls and 3, 4, 5, 6, 7 or 8 lateral walls, respectively, wherein the first and second end walls are opposite to each other and each of the lateral walls is connected to the first and second end walls and to two adjacent lateral walls, wherein the container has a triangular, quadrilateral (preferably square, rectangular, trapezoidal or parallelogram; more preferably, square or rectangular), pentagonal, hexagonal, heptagonal or octagonal cross section, respectively, formed by the lateral walls, said walls defining a volume for holding a liquid fuel for a liquid fuel cell or microformer; wherein the container has an outlet passageway through one of the walls suitable for the exit of the liquid fuel to a location exterior to the container, said outlet passageway optionally having a one-way valve that prevents the backflow of the liquid fuel into the container, and the container optionally having an inlet which optionally has a one-way valve allowing the flow of a gas or the liquid fuel into the container; and

[0104] (b) a wicking structure disposed within the volume of the container, wherein the wicking structure comprises a sheet or layer of a wicking structure material which can wick the liquid fuel and wherein the liquid fuel wicked into the wicking structure material can subsequently be discharged out of or released from the wicking structure material, and wherein the sheet or layer is disposed along or adjacent to all, or preferably all but one, of the lateral walls of the container, and wherein an edge of the sheet or layer is proximate (or in contact with) a portion of the first end wall and an opposite edge of the sheet or layer is proximate (or in contact with) a portion of the second end wall.

[0105] Within the aspect of the invention in which the liquid fuel reservoir has the external volume of the wicking structure minimized, in some of the embodiments, the container has 3 walls: a first and second end walls connected by a curved lateral wall, and a circular, oval or elliptic cross section formed by the curved lateral wall, wherein the wicking structure comprises a sheet or layer of the wicking structure material disposed along or adjacent to the curved lateral wall of the container, and wherein an edge of the sheet or layer is proximate or in contact with the first end wall and an opposite edge of the sheet or layer is proximate or in contact with the second end wall.

[0106] For fuel reservoirs intended for use in applications where the container orientation is expected to change during use, the container having a proximal end and a distal end with the proximal end being where the outlet passageway is disposed and the distal end being the end remote to the outlet passageway, the wicking structure preferably contacts at least one portion of the inner surface of the distal end of the container, and the wicking structure communicates with the outlet passageway. More preferably, the wicking structure contacts at least one portion of the inner surface of the distal end of the container and at least one portion, even more preferably a substantial portion, of the inner surface of a sidewall of the container, and the wicking structure also communicates with the outlet passageway. Most preferably, the wicking structure contacts at least one portion of the inner surface of the distal end of the container, at least one portion, even more preferably a substantial portion, of the inner surface of a sidewall of the container, and at least one portion of the inner surface of the proximal end of the container, and the wicking structure also communicates with the outlet passageway. Especially preferable is for the wicking structure to contact at least one portion of the inner surface of the distal end of the container, at least one portion (preferably a substantial portion) of the inner surface of a sidewall of the container, at least one portion of the inner surface of the proximal end of the container, and every extremity of the container volume, wherein the wicking structure communicates with the outlet passageway, so that the wicking structure is in fluid communication with every extremity of the container.

[0107] In an embodiment of the liquid fuel reservoir of the invention, a retainer is provided within the container. The retainer holds the wicking structure preferably in contact with at least one portion of the interior surface of the container having a proximal end and a distal end, wherein the outlet passageway is formed through the proximal end and the distal end is the end remote to the outlet passageway. The retainer holds the wicking structure more preferably in contact with at least one portion of the inner surface of the distal end of the container and with at least one portion of an inner surface of a sidewall of the container. Also more preferably, the retainer holds the wicking structure in contact with at least one portion of the inner surface of the distal end of the container and at least one portion (preferably that portion adjacent the outlet passageway) of inner surface of the proximal end of the container. Most preferably, the retainer holds the wicking structure in contact with at least one portion of the inner surface of the distal end of the container, at least one portion of the inner surface of a sidewall of the container, and at least one portion (preferably that portion adjacent the outlet passageway) of the inner surface of the proximal end of the container.

[0108] When the container has the retainer inside, the wicking structure is preferably mounted over at least a portion of the retainer, and the retainer is attached to a cap that engages the distal end of the container. With such an embodiment, the wicking structure so mounted over the retainer is slidably insertable into and optionally removable from the container.

[0109] In an alternative embodiment, the retainer comprises a connector extending from the inner surface of the distal end or from the inner sidewall surface of the container. The connector grips a portion of the wicking structure material to hold it in position within the container. As an example, the connector is a clamp, a combination of clamps, a toothed edge, or a VELCRO nub, each of which grasps a portion of the wicking structure material. For other embodiments, the wicking structure may be connected to the container by heat sealing, ultrasonic welding, molded in place by inserting the wicking material in an injection molding tool in order to avoid using any adhesive, or adhesive.

[0110] When the liquid fuel reservoir is provided with a retainer, the retainer preferably has a perforate structure to permit the liquid fuel to flow through the retainer structure and to minimize the effective volume occupied by the retainer in order to increase the amount of the liquid fuel that the fuel reservoir can hold. The effective volume of the retainer is the solid volume of the retainer, i.e. the volume occupied by the solid material of the retainer. In other words, the solid volume of the retainer is the total or external volume of the retainer minus the void volume of the retainer. The void volume of the retainer is the collective volume of any perforations of the retainer. More preferably, the retainer is of a material in the form of a screen, slotted sheet, or perforated sheet, each of which made of an appropriate fuel resistant material. For methanol as the liquid fuel, such fuel resistant materials include polypropylene, polyethylene, polyvinyl chloride, and the like.

[0111] While the wicking structure and the retainer, if present, can be sized to fill a substantial portion of the volume of the container, improved results can be achieved where a greater portion of the container volume is filled by the liquid fuel and a lesser portion of the container volume is taken up by the wicking structure and the optional retainer. It is desirable to minimize the volume effectively occupied by any internal structure(s) of the fuel reservoir in order to maximize the amount of liquid fuel that can be held in the container, and permit the liquid fuel in the container to be discharged therefrom in any orientation of the container, and at substantially any stage of liquid fuel depletion in the container with a minimum amount of retained liquid fuel. The internal structure(s) of the fuel reservoir includes the wicking structure in the absence of the retainer, or the wicking structure and the retainer, if present. Thus, it is desirable to minimize the sum of the solid volume of the wicking structure and the solid volume of the retainer, if present. The solid volume of the wicking structure is the volume occupied by the solid material of the wicking structure. In other words, the solid volume of the wicking structure is the external volume of the wicking structure minus its void volume. The void volume of the wicking structure is the total volume of all pores, perforations or interstices in the wicking structure. The external volume of the wicking structure is the volume of the wicking structure as defined by the external surface(s) of the wicking structure, so the external volume of the wicking structure is the sum of the solid volume and the total volume of all the pores or perforations in the wicking structure. In the event that the void volume of the wicking structure or the retainer is not known, or if a simpler, alternative approach is desired, the sum of the external volume of the wicking structure and the external volume of the retainer, if present, can be minimized in order to increase the amount of liquid fuel that can be held in the container.

[0112] Consequently, it is desirable to make the wicking structure comparatively thin. The volume taken up by the wicking structure can be further reduced by forming voids in the wicking structure, such as by perforating or slotting the wicking structure, so long as the wicking function is not impaired.

[0113] In an embodiment aimed at increasing the amount of liquid fuel that the fuel reservoir can hold, the solid volume of the wicking structure is preferably no more than 50% (e.g. less than 50%, such as no more than 45%), more preferably no more than 40% (e.g. no more than 25%), even more preferably less than 20% (e.g. no more than 12.5%), much more preferably less than 10% (e.g. no more than 5%), even much more preferably no more than 3%, and most preferably about 1%, of the volume within the container. The void volume of the wicking structure is preferably at least about 50%, more preferably about 60% to 98% (e.g. about 65% to 98%), even more preferably about 70% to 98% (e.g. about 70% to 85%), and most preferably about 80% to 98% (e.g. about 95%), of the external volume of the wicking structure. The solid volume of the retainer, if present, is preferably no more than about 15% (e.g. no more than about 12%), more preferably less than about 10% (e.g. no more than about 7%), much more preferably less than about 5% (e.g. no more than about 3%, such as about 1%) and most preferably less than about 1% (e.g. from about 0.5% to about 0.05%, such as about 0.5%, about 0.25%, about 0.1% or about 0.05%), of the volume within the container.

[0114] As an alternative, to increase the amount of the liquid fuel that the fuel reservoir can hold, the external volume of the wicking structure is preferably no more than about 65%, more preferably no more than about 50%, even more preferably no more than about 25%, and most preferably no more than about 10%, of the volume within the container. The external volume of the retainer, if present, is preferably no more than about 20%, more preferably no more than about 10%, even more preferably no more than about 5%, and most preferably no more than about 1%, of the volume within the container.

[0115] Referring to the drawings, some of the preferred embodiments of the invention are described below.

[0116] Referring first to FIG. 1, a fuel reservoir 10 is shown in combination with a pump 12 that directs liquid fuel such as methanol to a fuel cell 14 (indicated symbolically as a voltage source V), which is a source for power to a portable electronic device, such as a cellular telephone 14. The pump 12 communicates with an outlet passageway 24 of the fuel reservoir 10 to pump the liquid fuel out of the container 20 through the outlet passageway (see FIGS. 2 and 3). An inlet 26 having a one-way valve (not shown) is provided to the container 20 to permit gas flow into the volume of the container 20. In one of the embodiments, the container 20 is filled with 6 ml. of an aqueous fuel solution containing up to 100% methanol, preferably about 5% methanol. A pump 12 acts on the outlet tube 24 and draws liquid fuel 22 from the wicking structure 32 through the outlet tube 24. Only a slight vacuum needs to be placed on the outlet tube 24 to draw the fuel mixture out of the container.

[0117] As shown in greater detail in FIGS. 2-5, the fuel reservoir 10 has a container 20 formed as a case or cartridge that defines an internal volume holding a liquid fuel mixture 22. An outlet tube 24 extends into the container 20 through a proximal surface 38 and the outlet tube 24 communicates between the internal volume of the container 20 and the exterior of the container. An inlet tube 26 also extends into the container 20 through cover 38. The inlet tube 26 includes a one-way valve (not shown) so as to prevent liquid from flowing out of the container 20. Such a one-way valve may be placed on board the cartridge, or optionally on board the fuel cell. Alternatively, the inlet port may be connected to a waste stream from the fuel cell. Preferably, the gas entering the internal volume of the container 20 is air, but may also be an inert gas, such as nitrogen.

[0118] The materials forming the container 20 and tubes 24, 26 have to be fuel resistant. Where the fuel is methanol, the fuel resistant materials can be polypropylene, polyethylene, polyvinyl chloride and other appropriate materials. Where the fuel reservoir 10 is intended for use with a reformer, materials resistant to hydrocarbons should be used. Ideally, the tubes/vents 24, 26 will be injection molded together with the container 20 in one molding step.

[0119] A wicking structure 32 is provided within the volume of the container 20. The wicking structure 32 is mounted over a retainer 34. The retainer 34 is formed from a perforated sheet into a bent U shape that conforms to the shape of the internal side walls 36 and internal proximal end wall 38 of the container 20. The end portions 42 of the retainer 34 connect to the end cap 44 that closes the distal end of the container 20 when the container is filled with liquid fuel. When the end cap 44 closes the distal end of the container 20, the end cap 44 can be considered as a part, i.e. the distal end wall, of the container. Holes 46 through the thickness of the retainer 34 permit liquid fuel to contact the wicking structure 32. The retainer 34 urges and holds the wicking structure 32 into contact with the internal side walls and the internal proximal wall of the container, as well as an internal surface of the distal end wall 44 of the container. The wicking structure 32 thus is in communication with the internal opening of the outlet tube 24 of the container 20.

[0120] The cap 44 preferably also is made from a fuel compatible material, which generally will be the same as the material selected for the remainder of the container. In a preferred embodiment, the cap 44 is ultrasonically welded to the container 20 to create a fluid tight connection between the cap 44 and container 20.

[0121] In the embodiment shown in FIGS. 2-5, the wicking structure 34 is mounted on the retainer 32 and the retainer 32 is connected to the cap 44. As best shown in FIG. 2, when the cap 44 is removed from the container 20, the retainer 34 and wicking structure 32 are slidably removable from the container 20. Conversely, when the cap 44 is re-attached to the container 20, the retainer 34 and wicking structure 32 are slidably engageable with the container 20. The fuel reservoir or package is thus assembled by mounting the wicking structure onto the retainer, connecting the retainer to the cap and slidably engaging the wicking structure, retainer and cap with the container to place the wicking structure in communication with the outlet tube and distal portion(s) of the container volume. As stated, the cap 44 then can be sealingly connected to the container 20, such as by ultrasonic welding.

[0122] The wicking structure 32 is formed as a thin sheet or layer. Liquid fuel can wick into the wicking structure 32. The fuel reservoir 10 works best when the wicking structure 32 defines a path to direct the liquid fuel from the most distal portions of the container volume to the internal opening of the outlet tube 24. The fuel reservoir 10 may be used in all possible spatial orientations so long as the wicking structure 32 provides such fluid communication between the distal portions and the outlet tube 24. While it is possible to have a wicking structure 32 fill all or substantially all of the internal volume of the container 20, lesser amounts of wicking structure material may be used to direct and help meter or deliver the liquid fuel to the outlet tube 24. Thus, as shown in FIGS. 3 and 4, the wicking structure 32 extends to the distal end surface defining the internal fluid holding volume of the container, but this wicking structure 32 does not contact all internal surfaces of the container.

[0123] Referring back to FIG. 1, the connection between outlet tube 24 and the pump 12 may be a quick disconnection, so that the outlet tube 24 may be capped during storage and shipment before the fuel reservoir 10 is installed for use with a portable electronic device. A cap is not shown in FIG. 1, but the distal end of the container can be of any suitable construction that will maintain the liquid fuel within the container.

[0124] In an example of the embodiment shown in FIGS. 2 to 5, the wicking structure 32 is a felted polyurethane foam shaped as a thin sheet mounted over the retainer 34. The wicking structure can be a sheet of about 0.4 mm to about 2.5 mm thick. Preferably, the sheet of wicking material is between about 0.8 mm ({fraction (1/32)} inch) and about 1.6 mm ({fraction (1/16)} inch) thick.

[0125] The foam was produced with the following mix:

	Arcol 3020 polyol (from Bayer Corp.)	100	parts
	Water	4.7
	Dabco NEM (available from Air Products)	1.0
	A-1 (available for OSi Specialties/Crompton)	0.1
	Dabco T-9 (available from Air Products)	0.17
	L-620 (available from OSi Specialities/Crompton)	1.3

[0126] After mixing for 60 seconds and allowed to degas for 30 seconds, 60 parts of toluene diisocyanate were added. This mixture was mixed for 10 seconds and then placed in a 15155 box to rise and cure for 24 hours. The resulting foam had a density of 1.4 pounds per cubic foot and a pore size of 85 pores per linear inch. The foam was thermally reticulated, then felted by applying heat (360 F.) and pressure sufficient to compress the foam to of its original thickness (i.e., compression ratio5). The heat and compressive pressure were applied for about 5 minutes to a thickness of {fraction (1/32)} inch (0.8 mm). The resulting felted foam had a density of 7.0 pounds per cubic foot. When this felted foam was installed in a liquid fuel reservoir 10 such as shown in FIGS. 2-5, the liquid fuel reservoir had a 90% or greater fuel delivery efficiency, which means that 90% or more of the liquid fuel that was loaded into fuel-empty container could be discharged from the container and directed to a fuel cell used to power a portable electronic device at any spatial orientation of the fuel reservoir.

[0127] The retainer 34 preferably is formed from a material or a composite of materials that will not degrade when exposed to liquid fuels intended to be delivered via the liquid fuel reservoir. The preferred materials for the retainer 34 comprise those materials suitable for forming the container 20. In a most preferred embodiment, the retainer 34 is injection molded plastic, but it may also be formed as a screen or other slotted or perforated structure so long as it is able to retain the wicking structure 32 in place within the container 20.

[0128] The container of the fuel reservoir may take various shapes with various regular or irregular cross sections. Examples of regular cross sectional shapes include circular, oval, elliptic, rectangular, square, parallelogram, trapezoidal or triangular shapes. Oblong or other eccentric shapes as designed for installation in portable electronic devices are also within the scope of this invention. One preferred container shape is a generally cylindrical cartridge comparable in size and shape to disposable dry cell batteries, or other known battery cartridge shapes. Alternatively, in addition to the rectangular cross section of FIGS. 2-5, the container 20 is formed with a circular cross section (as shown in FIGS. 6 and 7), and a square cross section (as shown in FIGS. 8-10).

[0129] Referring next to FIGS. 6 and 7, the container 60 is formed as a cylinder, with a circular cross section. As with the embodiment shown in FIGS. 2-5, the fuel reservoir includes a wicking structure 62 and a retainer 64 that holds the wicking structure 62 in place within the volume of the container 60. The wicking structure 62 provides a path of liquid communication between the distal portions of the container 60 and the outlet tube 66. An inlet tube 68 having a one-way valve (not shown) that permits the entry of a gas into the container and prevents the exit of any liquid fuel is also provided. The wicking structure 62 is formed from a woven material, and the wicking structure is held in contact with the entire internal sidewall of the container 60.

[0130] Referring to FIGS. 8 and 9, the container 80 has a cubic shape with a square cross section. The wicking structure 82 is held in place by retainer 84. The wicking structure 82 is constructed of foam and provides a path of liquid communication between the distal portions of the container 80 and the outlet tube 86. In this embodiment, the retainer 84 is formed as a perforated sheet that holds the wicking structure 82 in contact with the inner side walls and inner proximal surface of the container 80, as well as with portions of the inner distal surface of the container at the four distal corners. The end cap 88 forming the distal end of the container may, but need not, be removable.

[0131] FIGS. 10 and 11 show an alternative embodiment using a different retainer and wicking structure. The container 100 comprises a generally cubic shape with a square cross section. The container 100 defines an internal volume for storing liquid fuel. L-shaped mounting clamps 102 extend from each corner of the distal internal surface of the container 100. A wicking structure 104 is formed as a central sheet 106 with four downwardly depending legs 108. The legs 108 extend toward the distal end internal surface of the container 100. The legs terminate at end portions that engage the L-shaped mounting clamps 102 at pins 103. In this embodiment, the mounting clamps 102 form the retainer to keep the end portions of the legs of the wicking structure 104 in position within the volume of the container 100. Fuel outlet tube 110 and inlet tube 112 extend into the container 100 at the proximal internal surface. The inlet tube 112 has a one-way valve (not shown) that permits the entry of a gas into the container. A backing plate 107 is connected to the sidewall of the container 100 with several supports 109 to hold the wicking structure 104 adjacent to the proximal internal surface of the container 100 and in fuel communication with the outlet tube 110. In this embodiment, the wicking structure 104 is positioned so as to direct liquid from the distal corners of the internal volume of the container 100 to the outlet tube 110. Even though the wicking structure does not contact completely any one of the internal sidewalls of the container, the wicking structure functions to direct liquid fuel to the outlet tube so that such fuel may be metered or pumped out of the fuel reservoir. Thus, in any orientation of the container 100, and at any stage of liquid fuel depletion within the container 100, the liquid fuel in the container will contact, or may be placed in contact with, wicking structure 104, either at central sheet 106 directly or through legs 108 to central sheet 106. Although not shown, alternatively the wicking structure can be modified by replacing the central sheet 106 with two linear members joined at the center to form a cross, wherein the ends of the two members are connected to the upper ends of the downwardly depending legs, and wherein the liquid fuel outlet tube extends through the proximal wall of the container to maintain fluid communication with the wicking structure by communicating with one of the two members, preferably with the junction of the two members, i.e. at the center of the cross.

[0132] Referring next to FIG. 12, an alternative structure for a liquid fuel reservoir has a container 120 defining an internal volume for holding a liquid fuel mixture 22. An outlet tube 124 extends into the container 120 through a first sidewall surface 122. The outlet tube communicates between the internal volume of the container 120 and the outside of the container. An inlet tube 126 also extends into the container 120 through first sidewall surface 122. The inlet tube includes a one-way valve (not shown) that permits the entry of a gas but prevents liquid from flowing out of the container 120. In the embodiment of FIG. 12, the outlet tube 124 and inlet tube 126 are disposed along a sidewall of the container 120, rather than along the proximal end wall as shown in earlier embodiments. An embodiment identical to the embodiment of FIG. 12 except for the positions of the inlet and outlet tubes is shown in FIG. 13. The outlet tube 124a is disposed along a sidewall of the container 120a, whereas the inlet tube 126a is disposed along a different sidewall in FIG. 13. Such alternative orientations for the inlet and outlet tubes may provide greater flexibility when the liquid fuel reservoir is used to power a portable electronic device.

[0133] In FIGS. 12 and 13, a wicking structure 130 is provided within the volume of the container 120. The wicking structure 130 is formed as an internal sleeve defining an inner core that is void of wicking material and having outer surfaces that contact the internal sidewalls of the container 120. The wicking structure 130 is held in contact with the internal sidewalls of the container by a retainer 128 that has perforations or channels 136 extending therethrough. The wicking structure 130 contacts the distal 132 and proximal 134 end walls of the container 120 at the corners thereof where these end walls join the sidewalls. However, the wicking structure 130 does not cover the entire internal surfaces of such distal 132 and proximal 134 end walls. The wicking structure is designed to contact such corners so that the liquid fuel mixture may be drawn into the wicking structure by capillary action independent of either (a) the orientation of the liquid fuel reservoir; or (b) the extent to which the container volume has been drained of the liquid fuel mixture. The wicking structure thus contacts the portions of the container volume most distant from the connection to the outlet tube and associated pump. Moreover, by reducing the amount of the wicking material used to form the wicking structure, less internal volume of the container is filled by the wicking material. Thus, because a portion of the liquid fuel remains within the wicking material as the container volume is emptied of liquid fuel, this embodiment can increase the efficiency of fuel delivery as compared to liquid fuel reservoirs where more wicking material is inserted into the volume of the container.

[0134] FIG. 14 shows yet another embodiment of a liquid fuel reservoir according to the invention in which a container 140 defines an internal volume for holding a liquid fuel mixture 22. An outlet tube 144 extends into the container 140 through a proximal end wall surface 148. The outlet tube communicates between the internal volume of the container 140 and the outside of the container. An inlet tube 146 extends into the container 140 through a distal end wall surface 150. The inlet tube 146 includes a one-way valve (not shown) so as to prevent liquid from flowing out of the container 140. In the embodiment of FIG. 14, the outlet tube 144 and inlet tube 146 are disposed at opposite ends of the container 140, rather than both being disposed from the proximal end wall or side walls as shown in earlier embodiments.

[0135] A wicking structure 154 is provided within the volume of the container 140. The wicking structure 154 is formed with an I-beam shape having flanges 162 disposed at each end of a column 160. The flanges 162 are held in contact with the internal proximal end wall 148 and internal distal end wall 150, respectively, with retainers 156 having perforations or holes 158 therethrough. As shown in FIG. 14, the column 160 is disposed centrally with respect to flanges 162 to form the I-beam shape. Alternatively, the column portion could connect the flange portions at other orientations, such as disposed along the internal side wall or disposed at a diagonal. The flanges 162 of the wicking structure 154 shown in FIG. 14 contact the corners of the internal volume of the container 140 where the sidewalls 142 meet the end walls 148, 150. The wicking structure is designed to contact such corners so that liquid fuel may be drawn into the wicking structure by capillary action independent of either (a) the orientation of the liquid fuel reservoir; or (b) the extent to which the container volume has been drained of the liquid fuel mixture. This configuration locates wicking material in the most distant crevices or extremities of the container, and by virtue of the capillarity of the wicking material, puts the distant crevices into fluid communication with the outlet tube and associated pump. Moreover, by reducing the amount of the wicking material used to form the wicking structure, less internal volume of the container is filled by wicking material. Thus, because a portion of the liquid fuel remains within the wicking material as the container volume is emptied of the liquid fuel, this embodiment can increase the efficiency of fuel delivery as compared to liquid fuel reservoirs where more wicking material is inserted into the volume of the container.

[0136] The amount of wicking material that is used to form a wicking structure for use in a liquid fuel reservoir according to the invention also can be minimized by removing or eliminating portions of the wicking material without adversely impacting the structural integrity or wicking ability of the wicking material. For example, where a foam is selected for the wicking material, the foam may be perforated by piercing or puncturing the foam to form holes therethrough. As shown in FIG. 15, a wicking structure 130b formed as a sleeve suitable for use in the embodiments of the invention shown in FIGS. 12 and 13, has been punctured to form holes 166 through the thickness of the foam material forming the wicking structure. Such holes can be provided in a regular or irregular pattern, although a regular grid-like pattern is shown in FIG. 15. Moreover, holes may be provided in the side walls of the wicking structure, although holes 166 are shown only through the top and bottom walls of the wicking structure 130b. Sufficient foam material is left in the wicking structure 130b so that such material will wick and deliver the liquid fuel to the outlet tube when pumping force is applied to the outlet.

[0137] A wicking structure with acceptable capillary or wicking characteristics but with lesser wicking material may also be formed from expanded foam or other sheet form wicking material. Referring to FIGS. 16 and 17, an expanded foam material is made by slitting through the thickness of a foam sheet 170 to form a series of slits 172 (FIG. 16). The foam sheet 170 is then stretched or pulled in the direction of arrows 176 (FIG. 17) to open the slits 172 to form open elongated slots 178. A wicking structure can then be formed from the expanded foam sheet 170a.

[0138] FIGS. 18-37 are schematic diagrams of a number of embodiments of the liquid fuel reservoir of the invention in which the external volume of the wicking structure is minimized to increase the amount of the liquid fuel that the reservoir can hold. For illustration purposes, these liquid fuel reservoirs all have a rectangular shape with a rectangular cross section in FIGS. 18-37. However, liquid fuel reservoirs of similar construction having a different shape, e.g. a rectangular shape with a square cross section or a cubical shape with a square cross section or irregular shapes, are also included within the scope of the invention.

[0139] As shown in FIG. 18, a liquid fuel reservoir 200 has a container 242 that defines a volume 246 for holding a liquid fuel mixture. A wicking structure 244 in the shape of two vertical posts linked to a crossbar at the top is provided along the inside top surface and inside side surfaces of the container 242. An outlet tube 248 and inlet tube 250 extend through a top wall of the container. The outlet tube 248 is in liquid communication with the wicking structure 244. The inlet tube 250 has a one-way valve (251) that permits the entry of a gas into the container and prevents the outflow of any liquid. FIG. 19 is a perspective view of the liquid fuel reservoir of FIG. 18. The wicking structure 244 extends substantially from the front to the back of the volume 246 inside the container 242, for example, by directly contacting the front and back walls of the container or by almost contacting the front and back walls (FIG. 19). With such a design, every extremity of the volume inside the container is in liquid communication with the outlet tube 248 at least through the wicking structure 244 via capillarity. This allows any liquid fuel inside the container to be delivered to the exterior of the container via a liquid delivery means, such as a pump, connected to the outlet tube 248 regardless of the amount of the liquid fuel that has been discharged from the liquid fuel reservoir and independent of the orientation of the liquid fuel reservoir.

[0140] FIGS. 20 and 21 show two other embodiments of the liquid fuel reservoir of the invention having the external volume of the wicking structure minimized. The liquid fuel reservoir 202, 204 includes a container 252, 262 defining a volume 256, 266, a wicking structure 254, 264 in the shape of a rectangular rim, and an outlet tube 258, 268 and an inlet tube 260, 270 extending through a top wall of the container. The outlet tube 258, 268 is in liquid communication with the wicking structure 254, 264. The inlet tube 260, 270 contains a one-way valve (261, 271) that permits the inflow of a gas and prevents the outflow of any liquid. The wicking structure 254, 264 is in contact with substantially the entire internal surfaces of the top, side and bottom walls of the container 252, 262. Although not shown, the wicking structure 254, 264 extends substantially from the front to the back of the volume of the container 252, 262 by contacting portions of the internal surfaces of the front and back walls of the container along or proximate the junctions of the front or back walls with the top, side or bottom walls. All the extremities of the volume inside the container are in liquid communication with the wicking structure via at least capillarity. The embodiments of FIGS. 20 and 21 differ only in the location of the outlet tube, with the outlet tube 258 disposed near the center of the top wall and the outlet tube 268 disposed near a corner.

[0141] FIGS. 22 and 23 show two other embodiments of the liquid fuel reservoir of the invention having the external volume of the wicking structure minimized. The liquid fuel reservoir 206, 208 includes a container 272, 282 defining a volume 276, 286, a wicking structure 274, 284 in the shape of an alphabet letter H, an outlet tube 278, 288 extending through a wall of the container, and an inlet tube 280, 290 extending through the same or a different wall of the container. The outlet tube 278, 288 is in liquid communication with the wicking structure 274, 284. The inlet tube 280, 290 contains a one-way valve (281, 291) that permits the inflow of a gas and prevents the outflow of any liquid. The wicking structure 274, 284 is in contact with substantially the entire internal side surface of the container 272, 282 and two portions each of the internal top and bottom surfaces of the container 272, 282 at or proximate the corners. Although not shown, the wicking structure 274, 284 extends substantially from the front to the back of the volume of the container 272, 282. All the extremities of the volume inside the container are in liquid communication with the wicking structure via at least capillarity. The embodiments of FIGS. 22 and 23 differ only in the location of the outlet tube with the outlet tube 278 extending through a side wall and the outlet tube 288 extending through a top wall of the container.

[0142] FIGS. 24 and 25 show two other embodiments of the liquid fuel reservoir of the invention having the external volume of the wicking structure minimized. The liquid fuel reservoir 210, 212 includes a container 292, 302 defining a volume 296, 306, a wicking structure 294, 304 in the shape of an alphabet letter X, an outlet tube 298, 308 extending through a wall of the container, and an inlet tube 300, 310 extending through the same or a different wall of the container. The outlet tube 298, 308 is in liquid communication with the wicking structure 294, 304. The inlet tube 300, 310 contains a one-way valve (301, 311) that permits the inflow of a gas and prevents the outflow of a liquid. The wicking structure 294, 304 is in contact with portions of the internal surfaces of the container 292, 302 at or proximate the corners. Although not shown, the wicking structure 294, 304 extends substantially from the front to the back of the volume of the container 292, 302. All the extremities of the volume inside the container are in liquid communication with the wicking structure via at least capillarity. The embodiments of FIGS. 24 and 25 differ only in the location of the outlet tube with the outlet tube 298 extending through a side wall and the outlet tube 308 extending through a top wall of the container.

[0143] FIGS. 26 and 27 show two other embodiments of the liquid fuel reservoir of the invention having the external volume of the wicking structure minimized. The liquid fuel reservoir 214, 216 includes a container 312, 322 defining a volume 316, 326, a wicking structure 314, 324 in the shape of an alphabet letter N, an outlet tube 318, 328 extending through a wall of the container, and an inlet tube 320, 330 extending through the same or a different wall of the container. The outlet tube 318, 328 is in liquid communication with the wicking structure 314, 324. The inlet tube 320, 330 contains a one-way valve (321, 331) that permits the inflow of a gas and prevents the outflow of any liquid. The wicking structure 314, 324 is in contact with substantially the entire internal side surface of the container 312, 322 and two portions each of the internal top and bottom surfaces of the container 312, 322 at or proximate the corners. Although not shown, the wicking structure 314, 324 extends substantially from the front to the back of the volume of the container 312, 322. All the extremities of the volume inside the container are in liquid communication with the wicking structure via at least capillarity. The embodiments of FIGS. 26 and 27 differ only in the location of the outlet tube with the outlet tube 318 extending through a top wall and the outlet tube 328 extending through a side wall of the container.

[0144] FIG. 28 illustrates another embodiment of the liquid fuel reservoir of the invention having the external volume of the wicking structure minimized. The liquid fuel reservoir 218 includes a container 332 defining a volume 336, a wicking structure 334 in the shape of an inverted alphabet letter M, an outlet tube 338 and an inlet tube 340 extending through a top wall of the container. The outlet tube 338 is in liquid communication with the wicking structure 334. The inlet tube 340 contains a one-way valve (341) that permits the inflow of a gas and prevents the outflow of any liquid. The wicking structure 334 is in contact with substantially the entire internal side surface of the container 332 and two portions each of the internal top and bottom surfaces of the container 332 at or proximate the corners. Although not shown, the wicking structure 334 extends substantially from the front to the back of the volume of the container 332. All the extremities of the volume inside the container are in liquid communication with the wicking structure via at least capillarity.

[0145] FIGS. 29 and 30 show two other embodiments of the liquid fuel reservoir of the invention having the external volume of the wicking structure minimized. The liquid fuel reservoir 220, 222 includes a container 342, 352 defining a volume 346, 356, a wicking structure 344, 354 in the shape of an alphabet letter K, an outlet tube 348, 358 extending through a wall of the container, and an inlet tube 350, 360 extending through the same or a different wall of the container. The outlet tube 348, 358 is in liquid communication with the wicking structure 344, 354. The inlet tube 350, 360 contains a one-way valve (351, 361) that permits the inflow of a gas and prevents the outflow of any liquid. The wicking structure 344, 354 is in contact with substantially an entire internal surface of a side wall of the container 342, 352, the internal surfaces of a portion of the other side wall and a portion of the top wall at or proximate where the other side wall and top wall meet, and the internal surfaces of a portion of the other side wall and a portion of the bottom wall at or proximate where the other side wall and bottom wall meet. Although not shown, the wicking structure 344, 354 extends substantially from the front to the back of the volume of the container 342, 352. All the extremities of the volume inside the container are in liquid communication with the wicking structure via at least capillarity. The embodiments of FIGS. 29 and 30 differ only in the location of the outlet tube with the outlet tube 348 extending through a side wall and the outlet tube 358 extending through a top wall of the container. The embodiment of FIG. 29 or 30 can be modified by having the wicking structure turned 90, so that the wicking structure resembles the alphabet letter K turned 90 when viewed from the front. In other words, the vertical member of the wicking structure that contacts substantially the entire inner surface of a side wall of the container in FIG. 29 or 30 becomes a horizontal member contacting substantially the entire inner surface of a top wall of the container and the wicking structure further has two slanted members being connected to the horizontal member at a location proximate the center of the horizontal member and extending to contact portions of the inner surfaces of the two side walls and a bottom wall proximate the corners opposite the top wall, i.e. the corners formed by the two side walls and the bottom wall of the container. Alternatively, these embodiments have the wicking structure in the shape of the alphabet letter K or K turned 90 can be modified by having two slant members not connected to each other, wherein the two slant members are still connected to the vertical or horizontal member, such that the wicking structure is in the shape of a symbol or turned 90 when viewed from the front. In these modified embodiments, the liquid fuel outlet tube should extend through the wall that the vertical or horizontal member of the wicking structure contacts in its substantial entirety, so that the liquid fuel outlet tube communicates with the vertical or horizontal member of the wicking structure. Although not shown, these modified embodiments of the embodiment according FIG. 29 or 30 are within the scope of the present invention.

[0146] FIGS. 31 and 32 show two other embodiments of the liquid fuel reservoir of the invention having the external volume of the wicking structure minimized. The liquid fuel reservoir 224, 226 includes a container 362, 372 defining a volume 366, 376, a wicking structure 364, 374 in the shape of an alphabet letter E, an outlet tube 368, 378 extending through a wall of the container, and an inlet tube 370, 380 extending through the same or a different wall of the container. The outlet tube 368, 378 is in liquid communication with the wicking structure 364, 374. The inlet tube 370, 380 contains a one-way valve (371, 381) that permits the inflow of a gas and prevents the outflow of a liquid. The wicking structure 364, 374 is in contact with substantially the entire internal surfaces of a side wall, top wall and bottom wall of the container 362, 372, a portion of the internal surface of the other side wall at or proximate where the other side wall and top wall meet, a portion of the internal surface of the other side wall at or proximate where the other side wall and bottom wall meet, and another portion of the internal surface of the other side wall. Although not shown, the wicking structure 364, 374 extends substantially from the front to the back of the volume of the container 362, 372. All the extremities of the volume inside the container are in liquid communication with the wicking structure via at least capillarity. The embodiments of FIGS. 31 and 32 differ only in the location of the outlet tube with the outlet tube 368 extending through a side wall and the outlet tube 378 extending through a top wall of the container.

[0147] As disclosed above, the location of the liquid fuel outlet passageway can be varied for some of the embodiments of the liquid fuel reservoir of the invention without affecting the aims of the invention. FIGS. 36 and 37 illustrate two more examples of varying the location of the liquid fuel outlet passageway for an embodiment of the liquid fuel reservoir having the external volume of the wicking structure minimized. The embodiments of FIGS. 36 and 37 are the same as that according to FIG. 18 except for the location of the liquid fuel outlet passageway. A liquid fuel reservoir 234, 236 is provided having a container 412, 422 that defines a volume 416, 426 for holding a liquid fuel mixture (FIGS. 36 and 37). A wicking structure 414, 424 in the shape of two vertical posts linked to a crossbar at the top is provided along the inside surfaces of the top and side walls of the container 412, 422. In the embodiment according to FIG. 36, an outlet tube 418 and inlet tube 420 extend through a side wall of the container. In contrast, an outlet tube 428 and inlet tube 430 extend through a bottom wall of the container in the embodiment of FIG. 37. The outlet tube 418, 428 is in liquid communication with the wicking structure 414, 424. The inlet tube 420, 430 has a one-way valve (421, 431) that permits the entry of a gas into the container and prevents the outflow of any liquid. The wicking structure 414, 424 extends substantially from the front to the back of the volume 416, 426 inside the container 412, 422, for example, by directly contacting the front and back walls of the container or by almost contacting the front and back walls. The present invention includes other embodiments of the liquid fuel reservoir that differ from the embodiments illustrated in the application in the location of the liquid fuel outlet passageway and/or the inlet.

[0148] FIGS. 33, 34 and 35 show three embodiments of the recyclable liquid fuel reservoir of the invention having the external volume of the wicking structure minimized. The liquid fuel reservoir 228, 230, 232 includes a container 382, 392, 402 defining a volume 286, 296, 406, a wicking structure 284, 294, 404 in the shape of a rectangular rim, and an outlet tube 388, 398, 408 and an inlet tube 390, 400, 410 extending through the top wall of the container. The outlet tube 388, 398, 408 is in liquid communication with the wicking structure 384, 394, 404. The inlet tube 390, 400, 410 contains a one-way valve (391, 401, 411) that permits the inflow of a gas and prevents the outflow of any liquid. The wicking structure 384, 394, 404 is in contact with substantially the entire internal surfaces of the top, side and bottom walls of the container 382, 392, 402. Although not shown, the wicking structure 384, 394, 404 extends substantially from the front to the back of the volume of the container 382, 392, 402. All the extremities of the volume inside the container are in liquid communication with the wicking structure via at least capillarity. The embodiments of FIGS. 33, 34 and 35 differ only in the means described below that allows the introduction of fresh liquid fuel into the container to replenish any liquid fuel which has been discharged.

[0149] In the recyclable liquid fuel reservoir of FIG. 33, a sealable, detachable cap 383 having a membrane 385 is provided at the end of the outlet tube 388. After the liquid fuel inside the container has been partially or completely discharged, the outlet tube can be disconnected from a liquid fuel cell or liquid fuel reformer and capped with the sealable cap 383. To replenish the container with a liquid fuel, fresh liquid fuel in a syringe can be introduced into the container 382 via injection after the membrane 385 is punctured with a syringe needle. When the syringe needle is withdrawn from the membrane 385 after the container is replenished with the liquid fuel, the membrane provides a liquid seal allowing the liquid fuel reservoir 228 to be stored or shipped for the next use. Alternatively, to replenish the container with a liquid fuel, fresh liquid fuel can be introduced into the container through the one-way valve of the inlet tube 390 after the outlet tube 388 has been capped with the sealable cap 383.

[0150] In the recyclable liquid fuel reservoir of FIG. 34, a two-way valve 393 is provided in the outlet tube 398. After the liquid fuel inside the container has been partially or completely discharged, the outlet tube can be disconnected from a liquid fuel cell or liquid fuel reformer and closed off with the two-way valve 393. To replenish the container with a liquid fuel, fresh liquid fuel can be introduced into the container 392 through the outlet tube 398 after the two-way valve 393 is opened, or through the one-way valve of the inlet tube 400 while the two-way valve 393 remained closed. After the container is replenished with the liquid fuel, the liquid fuel reservoir 230 can be stored or shipped for future use (if the two-way valve 393 has been open for liquid fuel replenishment, the valve should be turned off for storage or shipment).

[0151] In the recyclable liquid fuel reservoir of FIG. 35, a sealable, detachable cap 403 is provided for the outlet tube 408. The cap 403 is not attached to the outlet tube when the outlet tube is connected to a liquid fuel cell or liquid fuel reformer. After the liquid fuel inside the container has been partially or completely discharged, the outlet tube 408 can be disconnected from the liquid fuel cell or liquid fuel reformer. To replenish the container with a liquid fuel, fresh liquid fuel can be introduced into the container 402 through the inlet tube 410 via the one-way valve with the cap 403 not attached to the outlet tube 408, so that the outlet tube can act as a gas vent. After the container is replenished with the liquid fuel, the outlet tube 408 is closed with the cap 403 allowing the liquid fuel reservoir 232 to be stored or shipped for future use.

[0152] The recyclable liquid fuel reservoirs of FIGS. 33-35 are related to the liquid fuel reservoirs of FIGS. 20 and 21 in that the wicking structures of these liquid fuel reservoirs all have a configuration of a rectangular rim. The recyclable liquid fuel reservoirs of FIGS. 33-35 result from modifications of a liquid fuel reservoir similar to the embodiments of FIGS. 20 and 21 by adding a sealable, detachable cap with or without a membrane or a two-way valve at the outlet tube. Similar modifications can be made to the liquid fuel outlet tubes of other embodiments, e.g. the embodiments of FIGS. 18, 19, and 22-32, of the liquid fuel reservoirs to make recyclable versions of the liquid fuel reservoirs. These recyclable versions of the liquid fuel reservoirs are also within the scope of the invention.

[0153] FIGS. 38-40 show three embodiments of the liquid fuel reservoir of the invention in which the external volume of the wicking structure is minimized. The liquid fuel reservoir 237 in FIG. 38 comprises a container 432 having a square or rectangular cross section and six walls (two end walls and four lateral walls) defining a volume 436 for holding a liquid fuel inside the container. There is a wicking structure 434 having three contiguous sheets of wicking material disposed adjacent to three of the lateral walls of the container. An edge of the sheet of the wicking material is disposed proximate one of the end walls and the opposite edge of the sheet of the wicking material is disposed proximate the remaining end wall. In the embodiment shown in FIG. 38, an outlet passageway 438 and inlet 440 extend through one of the end walls. The liquid fuel reservoir 238 in FIG. 39 comprises a container 442 having a square or rectangular cross section and six walls (two end walls and four lateral walls) defining a 15 volume 446 for holding a liquid fuel inside the container. There is a wicking structure 444 having four contiguous sheets of wicking material disposed adjacent to the lateral walls of the container. An edge of the sheet of the wicking material is disposed proximate one of the end walls and the opposite edge of the sheet of the wicking material is disposed proximate the remaining end wall. In the embodiment shown in FIG. 39, an outlet passageway 448 and inlet 450 extend through one of the end walls. The liquid fuel reservoir 239 in FIG. 40 comprises a cylindrical container 452 having a circular cross section and three walls (two end walls and a curved lateral wall) defining a volume 456 for holding a liquid fuel inside the container. There is a wicking structure 454 having a sheet of wicking material disposed adjacent to the curved lateral wall of the container. Two opposite edges of the wicking structure are disposed proximate the two end walls of the container. In the embodiment shown in FIG. 40, an outlet passageway 458 and inlet 460 extend through one of the end walls.

[0154] FIGS. 41 and 42 show one of the embodiments of the liquid fuel reservoir 472 of the invention in a cylindrical shape. The reservoir has a wall 462, which defines a volume 466, an inlet tube 470 with a one-way valve 471, and an outlet tube 468. Inside the reservoir is a wicking structure 464, which comprises two horizontal circular plates proximate the internal surfaces of the two circular ends of the cylindrical reservoir interconnected with a central stalk extending through the volume 466.

[0155] FIGS. 43-48 show some of the embodiments of the liquid fuel reservoir of FIG. 18 having at least one porous internal compartment 241, which contains an impurities scavenger (not shown). FIG. 45 shows an embodiment having only one porous internal compartment 241. FIG. 46 shows another embodiment having two porous internal compartments 241, 243. FIGS. 47 and 48 show two alternative embodiments of the liquid fuel reservoir of FIG. 46, wherein the two porous internal compartments are separated (FIG. 47) or joined at one end with a third porous internal compartment 245 (FIG. 48). Optionally, the three porous internal compartments 241, 243 and 245 can be merged and replaced with one porous internal compartment having a cross section shaped like the alphabet letter, U.

[0156] FIGS. 49-51 show one of the embodiments of the liquid fuel reservoir of FIG. 18, having one porous internal compartment 247 proximate the internal surface of a wall of the container, wherein the internal surface is devoid of the wicking structure 244.

[0157] FIGS. 52-55 show some of the embodiments of the liquid fuel reservoir of FIG. 20 having at least one porous internal compartment 251 (FIGS. 52 and 53) or two porous internal compartments 251, 253 (FIG. 54). The embodiments have a wicking structure 254 shaped like a rectangular rim that lines the internal surfaces of two side walls and two end walls (FIGS. 52 and 55).

[0158] FIG. 56 shows an embodiment of the liquid fuel reservoir of FIG. 24 having two porous internal compartments 292, 293 containing an impurities scavenger (not shown).

[0159] FIGS. 57-60 show one of the embodiments of the liquid fuel reservoir of FIG. 40 having two porous internal compartments 451, 453, each in the shape of a circular disk containing an impurities scavenger (not shown).

[0160] FIGS. 61 and 62 show one of the embodiments of the liquid fuel reservoir of FIG. 41 having a porous internal compartment 461 in the shape of a cylinder disposed proximate a portion of the internal surface of the circular wall of the cylindrical liquid fuel reservoir, wherein the portion is free of the wicking structure 464.

[0161] FIG. 63 shows one of the embodiments of the liquid fuel reservoir of FIG. 38 having two porous internal compartments 431, 433 each in the shape of a square or rectangular flat plate, with the two porous internal compartments disposed proximate a portion of the internal surface of the top and bottom end walls of the container of the reservoir.

[0162] The liquid fuel reservoirs of the invention can contain an impurities scavenger in the outlet passageway or a filter cartridge connected to the outlet passageway. For instance, FIG. 64 shows an embodiment of the liquid fuel reservoir of FIG. 18 having an impurities scavenger 249 either in an outlet passageway 248 (FIG. 64A) or in a filter cartridge 800 connected to an outlet passageway 258 (FIG. 64B). The outlet port 810 of the filter cartridge 800 can be attached, directly or indirectly via a pump (not shown), to a liquid fuel cell (also not shown).

[0163] Examples of some of the embodiments of the liquid fuel reservoir of the invention having an impurities scavenger are shown in FIGS. 65-67. FIGS. 65, 66 and 67 show some of the embodiments of the liquid fuel reservoirs of FIGS. 20, 21 and 41, respectively, wherein the impurities scavenger 259, 269, 469 is located inside an outlet passageway 258, 268, 468.

[0164] The volume inside the containers of liquid fuel reservoirs shown in all the drawings can contain a liquid fuel, which optionally has an ingestion deterrent and/or flame brightener.

[0165] It is desired to have a fuel reservoir with a 90% or greater, preferably 95% or greater, efficiency in delivery of fuel to a liquid fuel cell or reformer. In this context, percent efficiency means the maximum amount of the fuel that can be drawn out of the container divided by the amount of fuel that was initially loaded into the fuel-empty container of the fuel reservoir. Depending upon the design parameters and use conditions, greater or lesser efficiencies may be acceptable.

[0166] An experiment was conducted to determine the removal of non-volatile residues (NVR), as impurities, from methanol by the following impurities scavenging substances: granulated carbon (203-67), granulated carbon (203-75A), Norit Darco G-60 (203-75B) and Calgon carbon (203-75D). NVR had been extracted from a piece of foam into the methanol to form a methanol solution containing NVR to be used in the impurities removal experiment. Separately for each of the above impurities scavenging substances, approximately 150 ml of the methanol solution containing NVR was placed in a beaker with a magnetic stir bar and the impurities scavenging substance was added in the amount shown in the table below, mixed for at least 24 hours, subjected to filtration if necessary to remove the impurities scavenging substance, distilled to dryness and weighed to determine the amount of NVR remaining. A control run was performed to determine the weight percent of NVR in the methanol not exposed to the impurities scavenging substance and the weight percent determined in the control run was used to calculate the expected amount of NVR in the methanol solution mixed with each of the impurities scavenging substances. The calculated expected amount of NVR was compared to the actual amount of NVR remaining after the removal of the impurities scavenging substance to calculate the percent of NVR removed by the impurities scavenging substance. Typical concentrations were less than 0.5% NVR in the methanol solution. As shown with the data below, the experiment demonstrated that the impurities scavenging substances can be used in powdered, granulated or pelletized form to remove impurities from the liquid fuel.

	203-67		203-75B	203-75D
	Granulated C	203-75A	Norit Darco G-60	Calgon C
	Packet Treat	Granulated C	Carbon	Pulverized Powder
D50% Particle Size	<5	mm	<5	mm	<45	microns	<1	mm
Gross	40.8502	40.3634	40.3449	41.1427
Tare	40.8419	40.3554	40.3391	41.1381
g NVR	0.0083	0.0080	0.0058	0.0046
Expected g NVR	0.0597	0.1074	0.1046	0.1061
g NVR scavenged	0.0514	0.0994	0.0988	0.1015
% NVR scavenged	86.1%	92.6%	94.5%	95.7%
g Carbon	2.1	4.1	4.1	4.1
Contact Time w/Solution	40	hrs	40	hrs	42	hrs	184	hrs
g NVR scavenged per g C	0.0245	0.0242	0.0241	0.0248

[0167] The invention has been illustrated by detailed description and examples of the preferred embodiments. Various changes in form and detail will be within the skill of persons skilled in the art. Therefore, the invention must be measured by the claims and not by the description of the examples or the preferred embodiments.