Patent Application
20220093375
The present embodiments relate to a system including a thermal energy harvesting thermionic device operatively coupled to or adapted to be operatively coupled to an appliance. Also provided are related systems and methods, including methods of making and using the system.
Existing electrochemical technologies, such as lithium-ion, lead-acid, and nickel-cadmium battery technology, have performance limitations and are burdened by limited operational durations due to limited energy storage. Further, existing electrochemical technologies include hazardous material subject to sometimes onerous handling, shipping, and disposal requirements. Furthermore, electrochemical technologies are also constrained by battery service and shelf-life limitations, particularly caused by electrochemical degradation under mechanical stress, and charge and discharge rates that limit operational lifetime.
The embodiments include systems, apparatus, and methods that include a thermal energy harvesting thermionic device operatively coupled to or adapted to be operatively coupled to an appliance.
In an aspect, a system is provided that includes an appliance adapted to generate thermal energy, a thermal energy harvesting thermionic device positioned proximal to the appliance to receive thermal energy from the appliance and generate an electrical output, an electrical conductive path configured to transfer electrical output from the thermal energy harvesting thermionic device to a load, and a heat-dissipating device positioned to reduce a temperature of the electrical conductive path by thermal exchange. The thermal energy harvesting thermionic device includes a cathode, an anode spaced from the cathode, and a plurality of nanoparticles in a medium contained in the space between the cathode and the anode. The nanoparticles are configured to permit electron transfer between the cathode and the anode.
In another aspect, a method is provided that includes providing a system including an appliance adapted to generate thermal energy, a thermal energy harvesting thermionic device positioned proximal to the appliance to receive thermal energy from the appliance and generate an electrical output, an electrical conductive path configured to transfer electrical output from the thermal energy harvesting thermionic device to a load, and a heat-dissipating device positioned to reduce a temperature of the electrical conductive path by thermal exchange. The thermal energy harvesting thermionic device includes a cathode, an anode spaced from the cathode, and a plurality of nanoparticles in a medium contained in the space between the cathode and the anode. The nanoparticles are configured to permit electron transfer between the cathode and the anode. According to the embodied method, the appliance generates thermal energy, which is transferred to the thermal energy harvesting thermionic device to generate the electrical output, which may be used to power the load. The temperature of the electrical conductive path is reduced using the heat-dissipating device.
In yet another aspect, a system is provided that includes an appliance comprising a housing and a heat source contained within the housing and adapted to generate thermal energy, a thermal energy harvesting thermionic device positioned within the housing of the appliance to receive the thermal energy from the appliance and generate an electrical output, an electrical conductive path configured to transfer electrical output from the thermal energy harvesting thermionic device to the appliance to power the appliance, and a heat-dissipating device positioned to reduce a temperature of the electrical conductive path by thermal exchange. The thermal energy harvesting thermionic device includes a cathode, an anode spaced from the cathode, and a plurality of nanoparticles in a medium contained in the space between the cathode and the anode. The nanoparticles are configured to permit electron transfer between the cathode and the anode.
In still another aspect, a method is provided that includes providing a system including an appliance adapted to generate thermal energy, a thermal energy harvesting thermionic device positioned within a housing of the appliance to receive thermal energy from a heat source within the housing of the appliance and generate an electrical output, an electrical conductive path configured to transfer electrical output from the thermal energy harvesting thermionic device to the appliance, and a heat-dissipating device positioned to reduce a temperature of the electrical conductive path by thermal exchange. The thermal energy harvesting thermionic device includes a cathode, an anode spaced from the cathode, and a plurality of nanoparticles suspended in a medium contained in the space between the cathode and the anode. The nanoparticles are configured to permit electron transfer between the cathode and the anode. According to the embodied method, the appliance generates thermal energy, which is transferred to the thermal energy harvesting thermionic device to generate the electrical output. The appliance is operatively connected to the thermal energy harvesting thermionic device to receive the electrical output from the thermal energy harvesting thermionic device for powering the appliance.
In a further aspect, a portable apparatus is provided that includes a portable housing, and an electrical energy storage device, a heat-generating source, and a thermal energy harvesting thermionic device within the housing. The housing includes at least one male electrical coupling member and at least one female electrical coupling member. The heat-generating source is operatively connected to the electrical energy storage device to convert electrical energy supplied by the electrical energy storage device to heat. The thermal energy harvesting thermionic device is proximal to the heat generating source to receive the thermal output from the heat-generating source and generate an electrical output. The thermal energy harvesting thermionic device is electrically connected to the at least one female electrical coupling member to provide the electrical output to the at least one female electrical coupling member. The thermal energy harvesting thermionic device includes a cathode, an anode spaced from the cathode, and a plurality of nanoparticles suspended in a medium contained in the space between the cathode and the anode. The nanoparticles are configured to permit electron transfer between the cathode and the anode.
In still a further aspect, a method is provided that includes providing a portable apparatus including a portable housing, and an electrical energy storage device, a heat-generating source, and a thermal energy harvesting thermionic device within the housing. The housing includes at least one male electrical coupling member and at least one female electrical coupling member. The heat-generating source is operatively connected to the electrical energy storage device to convert electrical energy supplied by the electrical energy storage device to thermal output. The thermal energy harvesting thermionic device is positioned proximal to the heat-generating source to receive the thermal output from the heat-generating source and to generate an electrical output. The thermal energy harvesting thermionic device is electrically connected to the at least one female electrical coupling member. The thermal energy harvesting thermionic device includes a cathode, an anode spaced from the cathode, and a plurality of nanoparticles suspended in a medium contained in the space between the cathode and the anode. The nanoparticles are configured to permit electron transfer between the cathode and the anode. According to an embodiment, the at least one male electrical coupling member of the portable apparatus is electrically coupled to an electrical power source to charge the electrical energy storage device. The at least one male electrical coupling member is electrically uncoupled from the electrical power source. The at least one female electrical coupling member is electrically coupled to an appliance. Electrical energy from the electrical energy storage device is supplied to the heat-generating source to generate thermal output, which is used by the thermal energy harvesting thermionic device to generate electrical output. The electrical output is supplied to the appliance electrically coupled to the at least one female electrical coupling member to operate the appliance.
Other aspects disclosed herein include systems, devices, components, apparatus, methods, and processes. Features of these and other aspects will become apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings.
The drawings referenced herein form a part of the specification. Features shown in the drawings are meant as illustrative of only some embodiments, and not of all embodiments, unless otherwise explicitly indicated.
It will be readily understood that the components and features of the exemplary embodiments, as generally described herein and illustrated in the Figures, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the methods, devices, assemblies, apparatus, systems, compositions, etc. of the exemplary embodiments, as presented in the Figures, is not intended to limit the scope of the embodiments, as claimed, but is merely representative of selected embodiments.
The illustrated embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and illustrates certain selected embodiments of methods, devices, assemblies, apparatus, systems, etc. that are consistent with the embodiments as claimed herein.
Reference throughout this specification to “a select embodiment,” “one embodiment,” “an exemplary embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in a select embodiment,” “in one embodiment,” “in an exemplary embodiment,” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment. The embodiments may be combined with one another in various combinations and modified to include features of one another.
Referring now more particularly to
The system (102) includes an appliance (104), a thermal energy harvesting thermionic device, generally designated by reference numeral (110), a heat dissipation device (also referred to herein as a heat dissipater) (120), and an electrical conductive path (132) including one or more electrical conductors. Portions of the electrical conductive path (132) connected to or passing through parts or components, such as the heat dissipation device (120), load (130), and walls of a housing (112) of the thermionic device (110), are sometimes shown as broken or dashed lines passing through the parts or components. The one or more electrical conductors can be, for example, one or solid electricity-conveying members such as wires, traces, electrical ink, electrical lines, etc.
Appliance (104)
The appliance (104) is a power-consuming device that during operation generates thermal energy (or heat). The appliance (104) may be in the form of a physical device, apparatus, machine, or equipment configured for use in a commercial or domestic domain. In an exemplary embodiment, the appliance (104) is electrically or at least partially electrically operated. With respect to the domestic domain, the appliance (104) may be, but not limited to, electrically operated for use in the home or for performance of domestic chores. Examples of appliances (104) include, without limitation, refrigerators, freezers, washing machines, dryers, dishwashers, ranges, ovens, stoves, microwaves, toasters, mixers, vacuums, air conditioners, air purifiers, garbage disposals, trash compacters, water heaters, etc. In an embodiment, the appliance (104) may be in the form of a portable electrically operated device, apparatus, or machine, such as but not limited to a mobile telephone, e.g., cellphone, tablet computer, laptop computer, watch, etc. Most electrical appliances are designed to operate using either alternating current (e.g., a utility grid connected to a wall outlet) or direct current (e.g., an electrochemical battery) sources. Batteries, for example, may be internal or external to the appliance, and may be rechargeable or replaceable.
Appliances, whether residential, domestic or commercial, generate thermal energy in one or more of a number of ways, including through the use of resistors or as a by-product of power production, e.g., heat generated by the operation of a motor or compressor or other operative mechanism of the appliance.
As discussed in further detail below, the thermal energy harvesting thermionic device (110) is positioned proximal to (e.g., below, on, next to) the appliance (104) to both cool the appliance (104) by drawing heat away from the appliance (104) and to synergistically generate power. In
Thermal Energy Harvesting Thermionic Device (110)
As shown in
A housing (112) is provided to enclose the cathode (114), the anode (116), and the nano-fluid in the inter-electrode gap (118). According to an exemplary embodiment, the housing (112) is made of an aerogel material. However, the housing (112) may be made of other materials, whether conductive, semi-conductive, or insulating. Representative materials include metals, alloys, plastics, glass, etc.
The thermal energy harvesting thermionic device (110) operates on a thermionic power conversion principle to convert thermal energy (106) supplied by the appliance (104) into electrical energy (electricity) by an emission of electrons from the cathode (114), which is also referred to herein as an emitter electrode. The production of electrons from the cathode (114) is controlled by barriers to the flow of electricity. The first barrier to be overcome involves establishing electron energy that is sufficiently large to exceed the work function of the cathode (114) to enable electron emission from a surface of the cathode (114), such as the first surface (114A) of the cathode (114). At lower temperatures, only a fraction of the electrons have sufficient energy to allow thermionic emission to proceed, thus limiting current flow. Intermediate and elevated temperatures provide higher energy than lower temperatures, with the intermediate temperatures giving rise to an increase in electron production at the cathode surface (114A) of the cathode (114) due to an increased or larger distribution of electrons with the required energy for emission. As kinetic energy of the electrons is dependent upon the temperature of the cathode (114), increasing the temperature of the cathode (114) results in an increase in electron emission, and hence electrical current.
The electrons emitted from the cathode (114) cool the cathode (114) in a similar way that rain evaporating from roof carries away heat. The “hot” electrons emitted by the cathode (114) pass through the nano-fluid in the inter-electrode gap (118) and heat the anode (116), which is also referred to herein as a collector electrode. This movement of electrons sets up a thermal gradient for a nanoscale heat engine.
Electrons flow from the cathode/emitter electrode (114), across the nano-fluid in the inter-electrode gap (118), to the anode/collector electrode (116). As shown, the anode (116) is spaced from the cathode (114) by the inter-electrode gap (118), as shown and described in
Recent improvements in thermionic power converters pertain to material selection based on work functions and corresponding work function values for the electrodes and using a fluid to fill the inter-electrode gap. Electron transfer density is limited by the materials of the electrodes and the materials of the fluid in the inter-electrode gap (i.e., the associated work functions). Representative and exemplary materials, features, conditions, etc. associated with thermal energy harvesting thermionic devices are described in further detail below, including in connection with
As noted, thermal energy causes electrons to flow from the cathode (114) to the anode (116). Accordingly, the appliance (104) is placed in closer proximity to the cathode (114) than the anode (116) of the thermal energy harvesting thermionic device (110) in an exemplary embodiment. As shown in the example of
While in exemplary embodiments described above, the thermal energy harvesting thermionic device (110) harvests thermal energy from the appliance (104), in exemplary embodiments the thermionic device (110) also harvests ambient heat from air and uses the ambient heat to generate additional electricity. Additionally, although not shown in
Heat Dissipation/Heat Dissipation Device (120)
According to an exemplary embodiment, a design feature of an exemplary embodiment of the circuit is that the size, e.g., diameter, of the return wire or other electrical conductive path(s)/connector(s) (132) is small enough to transfer heat readily back to the cathode (114) without creating a large resistance. The temperature or average energy of electrons is reduced due to thermal exchange of heat leaving the anode (116) to a heat dissipation device (also referred to and embodied herein as a heat dissipating device) (120), such as a heat exchanger or a heat sink. The electron flow with a reduced thermal energy is delivered to the load (130), thereby reducing the likelihood that the load (130) will overheat. The electrons then flow back to the cathode (114) to maintain the thermionic device operating at a high efficiency. In an exemplary embodiment, the heat-dissipation device (120) is a microstructure array heat exchanger. Implementation of the heat dissipating device (120) functions to reduce an average energy of electrons leaving the anode (116). Returning electrons that are re-supplied to the cathode/emitter electrode (114) will therefore complete a heat engine cycle with a lower average energy leaving an operatively coupled load (130) than supplied to the load.
The heat-dissipation device (120) may be embodied as, for example, a heat sink or a heat exchanger. In an exemplary embodiment, the heat-dissipation device (120) comprises a micro-structure array heat exchanger. Referring to
The heat-dissipation device (600) includes a plurality of rings, annular fins, or arcuate surfaces, hereinafter referred to as annular fins, and illustrated as first, second, and third annular fins (602), (604), and (606), respectively. Although three annular fins (602), (604), and (606) are shown in
In
The first, second, and third annular fins (602), (604), and (606), respectively, include corresponding openings, shown in
As shown in
In an exemplary mode of operation, heat conveyed by the electrical conductor (620) is removed in part by the fins (602), (604), and (606) and transmitted to the base (610), which together function as a heat sink.
Load (130)
The thermal energy harvesting thermionic device (110) is electrically coupled to the load (130) by the electrical conductive path (132). In exemplary embodiments, the load (130) can be, for example, a power-consumption device and/or a rechargeable power storage device. Arrow (134) represents the flow direction of electrons leaving the anode (116).
For embodiments in which the electrical load (130) is embodied as a power-consumption device, the load (130) may be selected from a wide array of consumer and commercial products and goods, including, by way of example and not limitation, mobile telephones, cordless telephones, consumer electronics, portable electronics, computers such as laptop computers and tablet computers, personal digital assistants (PDAs), portable radios, power tools, watches, calculators, game systems and controllers, cameras, video recorders, portable televisions, global positioning systems (GPS), data transfer devices, home-consumer appliances, lighting goods and systems, home products, toys, headphones, DVD and CD players, MP3 players, voice recorders, sensors, controllers, grooming instruments, alarm systems, weapons such as stun guns, backup power sources, military equipment, emergency equipment, utility equipment, vehicle controls and systems, appliances, telecommunications, etc.
Appliances are conveniently cooled by natural convection and radiation or through the use of fluid movers, e.g. fans, especially internal fans. In an embodiment, natural convection cooling is desirable, since natural convection cooling does not involve fans that may break down or consume harvested energy. Natural convection is based on fluid motion caused by density differences driven by a temperature difference.
A first difference between the block diagrams (100) and (200) of
Examples of commercial TIM suppliers and materials include, without limitation, 3M (D270 Epoxy), Henkel AG and Co. (Loctite 315), Hitachi Chem. Corp. (XH9930-2), DOW Chemicals (TC-2035), and Kyocera Chem. Corp. (CT284R).
A second difference between the block diagrams (100) and (200) of
Referring to
A first difference between the block diagrams (100) and (300) of
A second difference between the block diagrams (100) and (300) of
A third difference between the block diagrams (100) and (300) of
Referring to
A difference between the block diagrams (300) and (400) of
The apparatus (402) also includes a fluid-circulating device (422) operatively coupled to a thermal reservoir (424). The fluid-circulating device (422) may be, for example, one or more fans, impellers, blowers, or any device configured to facilitate fluid flow. Although the fluid-circulating device (422) is depicted enclosed within the appliance housing (408), it should be understood that the fluid-circulating device (422) may be externally situated with respect to the appliance housing (408). The fluid-circulating device (422) communicates with the thermal reservoir (424) via a pathway for thermal communication (426). The fluid-circulating device (422) may provide cooling fluid (e.g., gas, such as air) to the heat dissipation device (420), and thereby remove heat from the heat dissipation device (420), or exchange fluid (e.g., air) between the heat dissipation device (420) and the thermal reservoir (424). The pathway, also referred to herein as a passage, for thermal communication (426) may comprise, for example, one or more conduits, pipes, vents, ducts, other parts and passages, and/or combinations thereof. The thermal reservoirs (424) may comprise, for example, one or more cooling fluid reservoirs.
As shown, the apparatus (1800) includes a plurality of thermal energy harvesting thermionic devices, shown herein as a first thermal energy harvesting thermionic device (1810) and a second thermal energy harvesting thermionic device (1812), positioned within the housing (1802). The first and second thermionic devices (1810) and (1812), respectively, are shown arranged in side-by-side (adjacent) relationship to one another. Alternative arrangements may be practiced, including stacked and other arrangements. For example, the first thermionic device (1810) can be positioned on the first (right) side (1802c) of the housing (1802) and the second thermionic device (1812) can be positioned adjacent to the opposite second (left) side (not shown) of the housing (1802). Alternatively, the thermionic devices can be positioned adjacent to the first surface (1802A) and/or the opposite second surface (not shown in
While
In exemplary embodiments, the thermionic device or devices, e.g., (1810) and (1812) provide structural support for and add structural integrity to the appliances, e.g., the apparatus (1800), while adding minimal mass and size to the appliance(s).
Another exemplary embodiment will now be discussed in connection with
As shown herein, the portable apparatus (or charger) (550) is provided to receive the plug (582). The apparatus (550) includes a portable housing (552) defining a body with a chamber or compartment (553) (
The rear face (556) of the apparatus (550) includes a male electrical coupling member embodied as male electrical contact prongs (564A) and (564B) extending from the housing (552). The male electrical contact prongs (564A) and (564B) are configured for electrically coupling with a socket of a standard AC outlet, such as either of the sockets (592) or (594) of the wall outlet (590) for charging the apparatus (550). Projecting lines in
The apparatus (550) includes additional components for creating and/or supplying a power reserve for operation of the appliance (504), such as in the event that electricity is not available from an electrical outlet, e.g., outlet (590). A thermal energy harvesting thermionic device (510) is positioned within the body encompassed or defined by the housing (552). In an exemplary embodiment, a plurality of interconnected thermal energy harvesting thermionic devices (see
Also positioned within the housing (552) are an electrical energy storage device (570), a heat source (572), and a controller (574). The electrical energy storage device (570), the heat source (572), and the controller (574) are shown in broken lines or dashes in
As shown in
In an exemplary embodiment, one or more capacitors are selected as the electrical energy storage device (570), although other devices capable of storing electrical energy, e.g., a charge, may be used. Unless otherwise indicated, the term capacitor can include supercapacitor, micro-capacitor, micro-supercapacitor, and the like. Examples of electrical energy storage devices that may be used instead of or in combination with one or more capacitors include, without limitation, inductors, fuel cells, non-rechargeable batteries, re-chargeable batteries, and other electrical energy storage elements.
In an exemplary embodiment, the controller (574) detects an electrical coupling between the apparatus (550) and a power source (590), and more particularly insertion of the male electrical contact prongs (564A) and (564B) into the receptacles (596A) and (596B), respectively, of the electrical socket (592). Electrical energy is stored in the electrical energy storage device (570) by electrically coupling the apparatus (550) with the power source (590). In particular, the male electrical contact prongs (564A) and (564B) are inserted into the respective receptacles (596A) and (596B) of the socket (592), as shown by the dashed projecting lines in
In use, the portable apparatus (550) is electrically coupled to the appliance (504). Turning the appliance (504) on closes switch (508) of the appliance (504). In an exemplary embodiment, the controller (574) detects the position of the switch (508) and the electrical coupling between the appliance (504) and the apparatus (550), and more particularly insertion of the male electrical contact prongs (584A) and (584B) of the plug (582) into the receptacles (562B) and (562A), respectively, of the electrical socket (560). The electrically coupling between the appliance (504) and the apparatus (550) causes the controller (574) to close the switch (566). Electricity generated by the thermionic device (510) is supplied to the appliance (504) across the closed switches (508) and (566).
In an embodiment, the controller (574) includes one or more temperature sensors such as the temperature sensor (576), which may be embodied as one or more thermocouples. Although the controller (574) and the temperature sensor (576) are depicted in
The controller (574) is operatively connected to the temperature sensor (576) to monitor the temperature of the thermionic device (510) or one or more of the components of the thermionic device (510). In an exemplary embodiment, the temperature of the cathode or a conductor contacting the cathode is monitored by the controller (574) and the temperature sensor (576). In another embodiment, the temperature of the anode or a conductor operatively coupled to the anode is monitored. In still another embodiment, the temperature of the nano-fluid is monitored by the controller (574) and the temperature sensor (576).
The controller (574) and the temperature sensor (576) monitor the temperature of the thermal energy harvesting thermionic device (510) or a component thereof for a temperature drop below a temperature threshold. In an embodiment, the temperature threshold is a temperature value. In another embodiment, the temperature threshold is a range of temperatures. The temperature threshold may be predetermined. For example, the temperature threshold may be any value between the freezing point and the boiling point of the nano-fluid (discussed below) of the thermal energy harvesting thermionic device (510). In another embodiment, the temperature threshold is a temperature difference (temperature gradient) between the cathode and anode.
In response to detection that the temperature (as monitored by the temperature sensor (576)) of the thermal energy harvesting thermionic device (510) has fallen below the temperature threshold, the controller (574) closes switch (567). Electricity is supplied from the electrical energy storage device (570) through the solid state relay (575) to the heat source (572). As current (typically direct current (DC)) flows from the electrical energy storage device (570) to the heat source (572), the electrical energy is converted by the heat source (572) into heat (or thermal energy).
In an exemplary embodiment, heat is the by-product of resistance of a circuit component, including but not limited to resistors. In an exemplary embodiment, the heat source (572) comprises one or more resistors. Various types of resistors may be employed. In an exemplary embodiment, selection or employment of resistors is configurable. For example, resistors suitable for use as the heat source (572) may have a resistance in a range of, for example, about 0.01 ohms to about 10 k ohms (10,000 ohms) and/or a power dissipation rating of, for example, about 0.001 watts to about 1 or more megawatts. Other heating sources with low thermal resistance change may be used instead of or in addition to a resistor.
The heat source (572) is positioned proximal to the thermal energy harvesting thermionic device (510) so that the thermal energy generated by the heat source (572) thermally perturbs the thermal energy harvesting thermionic device (510). In an exemplary embodiment, the controller (574), through switch activation, activates the heat source (572) to generate a temperature in a range of about −200° C. to about 2,000° C. In an exemplary embodiment, the temperature range is correlated with the composition of the nano-fluid. For example, at −200° C. the nano-fluid composition may include an alkali metal, and at the highest temperature range the nano-fluid composition may include molten salts. Similarly, in another embodiment, at room temperature, such as 25° C. to 200° C., the nano-fluid composition may include organics, such as toluene, alkanes, alkane thiols, and/or water, with each composition having respective operational temperatures or temperature ranges.
In an exemplary embodiment, the controller (574) closes the switch (567) for a period of about 4-10 seconds to about 100 seconds, which is sufficient time for the electrical energy storage device (570) to supply electricity to the heat source (572) to generate heat for harvesting by the thermal energy harvesting thermionic device (510). The amount of time selected for activating the electrical energy storage device (570) may be based on various factors, including but not limited to the ambient temperature of the environment in which the device (510) is located, the temperature of the nano-fluid prior to activation, etc. The magnitude of the resulting current produced by the thermal energy harvesting thermionic device (510) will depend upon many factors, including the heat energy emitted by the heat source (572). In an exemplary embodiment, activating the heat source (572) for a limited duration, e.g. seconds, can increase the electrical output of the thermal energy harvesting thermionic device (510) for an extended duration, e.g. hours.
The electricity channeled through the heat source (572) and generated by the thermionic device (510) charges the electrical energy storage device (570) and supplies electricity to the appliance (504). As best shown in
When the appliance (504) is turned off or unplugged from the electrical socket (560) of the apparatus (550), the controller (574) opens the switch (566) and, if closed, the switch (567) as well.
The controller (574), which may be embodied as a control circuit, may include at least one processor (e.g., a microprocessor), at least one microcontroller, at least one programmable logic device (e.g., field programmable gate arrays, programmable array logic, programmable logic devices), at least one application specific integrated circuit, or the like, or combinations including one or more thereof. The controller (574) may include or operatively communicate with a memory or memory module. Memory or memory modules may be in the form of nonvolatile data stores, such as hard drives and/or nonvolatile memory. A non-exhaustive list of more specific examples of memory includes the following: a portable computer diskette, a hard disk, a dynamic or static random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a magnetic storage device, a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, and any suitable combination of the foregoing. The memory may store one or more software-based control applications that include instructions that the control circuit executes to perform the functions described herein.
The housing (552) is depicted in
In the apparatus (550C) of
Positioning the thermionic device (510C) and the heat source (572C) outside of the internal housing/heat shield (568C) exposes the thermionic device (510C) and the heat source (572C) to thermal energy or heat (506C) generated by the appliance (504C). A break or opening proximal to the appliance (504C) and the thermionic device (510C) may be provided in the housing (552C) for increasing the exposure of the thermionic device (510C) to the heat (506C) generated by the appliance (504C). This thereby reduces the burden on the electrical energy storage device (570C) to provide electricity for activating the heat source (572C).
An additional feature that may be practiced with the apparatus (550C) of
Although some embodiments disclosed herein involve use of the apparatus or system (102) with a rechargeable electrochemical battery for recharging the battery, in exemplary embodiments the electrochemical battery is omitted to eliminate the various problems associated with electrochemical battery use, including electrochemical degradation and recharge cycles. Further, exemplary embodiments of the thermionic devices can operate at power densities (e.g. 1500 watts/kg) exceeding those of lithium ion batteries, avoid the need for potentially harmful and/or hazardous electrochemical materials, have long service and shelf lives, can operate under mechanical stress conditions, and/or reduce life-cycle costs.
Re-Chargeable Power Storage Embodiments
In an embodiment, a re-chargeable power storage device can be electrically coupled to the power-consumption device to discharge electrical energy into the power-consumption device, and to be re-charged in multiple cycles. In an exemplary embodiment, the re-chargeable power storage device comprises one or more re-chargeable batteries. Non-limiting examples of re-chargeable batteries include lithium ion, lithium-ion polymer, lead-acid, nickel-cadmium, and nickel-metal hydride batteries. In another embodiment, the re-chargeable power storage device comprises one or more secondary cells. In the embodiment of
The charging circuit (1900) of
The thermal energy harvesting thermionic device (1910) functions as a power source in the charging circuit (1900) shown in
The charging circuit (1900) of
Thermal Energy Harvesting Thermionic Devices (110), (210), (310), (410), (510)
Embodiments of the thermal energy harvesting thermionic devices (110), (210), (310), (410), and (510) are described in greater detail with reference to
The thermal energy harvesting thermionic device (700) is sometimes referred to herein as a cell. In exemplary embodiments, the thermal energy harvesting thermionic device (700) is illustrated as a sheet or a plurality of adjacently positioned sheets or layers, e.g., that may be stacked or wound. A plurality of devices (700) may be organized as a plurality of cells, or a plurality of layers, with the cells or layers arranged in series or parallel, or a combination of both to generate electrical output at the desired voltage, current, and power.
The thermal energy harvesting thermionic device (700) includes an emitter electrode (also referred to herein as the cathode) (702) and a collector electrode (also referred to herein as the anode) (704) positioned to define an inter-electrode gap (or interstitial space) therebetween. In an embodiment, a spacer (706) of separation material, sometimes referred to herein as a standoff or spacer, maintains separation between the electrodes (702) and (704). While the spacer (706) is referred to herein in the singular, it should be understood that the spacer (706) may comprise a plurality of elements. The spacer (706) may be a dielectric or insulator, or comprise one or more materials that collectively exhibit electrically non-conductive properties. The spacer (706) is illustrated in direct contact with the electrodes (702) and (704). The electrodes (702) and (704) and the spacer (706) define a plurality of closed apertures (708), also referred to herein as cavities, in the inter-electrode gap. The apertures (708) extend in the Y direction between the electrodes (702) and (704) for a distance (710) in a range, for example, of about 1 nanometer (nm) to about 100 nm, or in a range, for example, of about 1 nm to about 20 nm. A fluid (712), also referred to as a nano-fluid (discussed further herein with reference to
In alternative embodiments, no spacer (706) is used and only the nano-fluid (712) is positioned between the electrodes (702) and (704). Accordingly, the thermal energy harvesting thermionic device (700) includes two opposing electrodes (702) and (704), optionally separated by the spacer (706) with a plurality of apertures (708) extending between the electrodes (702) and (704) and configured to receive the nano-fluid (712).
The emitter electrode (702) and the collector electrode (704) each may be fabricated from different materials, with the different materials having separate and different work function values. The work function of a material or a combination of materials is the minimum thermodynamic work, i.e., minimum energy, needed to remove an electron from a solid to a point in a vacuum immediately outside a solid surface of the material. The work function is a material-dependent characteristic. Work function values are typically expressed in units of electron volts (eV). Accordingly, the work function of a material determines the minimum energy required for electrons to escape the surface, with lower work functions generally facilitating electron emission.
The difference in work function values between the electrodes (702) and (704) due to the different electrode materials influences the voltage that can be achieved. Thus, to generate high power, the difference in work function values between the electrodes (702) and (704) is large in an exemplary embodiment. In an embodiment, the work function value of the collector electrode (704) is smaller than the work function value of the emitter electrode (702). The different work function values induces a contact potential difference between the electrodes (702) and (704) that has to be overcome, e.g., by the application of heat to the emitter electrode (702), to transmit electrons through the nano-fluid (712) within the apertures (708) from the emitter electrode (702) to the collector electrode (704). The total of the work function value of the collector electrode (704) and the contact potential difference is less than or equal to the work function of the emitter electrode (702) in an exemplary embodiment. Maximum flow occurs when the total of the work function value of the collector electrode (704) and the contact potential equals the work function of the emitter electrode (702).
Both electrodes (702) and (704) emit electrons; however, once the contact potential difference is overcome, the emitter electrode (702) will emit significantly more electrons than the collector electrode (704), which is influenced by an electric field that suppresses electron production from the collector electrode (704). A net flow of electrons is transferred from the emitter electrode (702) to the collector electrode (704), and a net electron current (714) flows from the emitter electrode (702) to the collector electrode (704) through the apertures (708). This net electron current (714) causes the emitter electrode (702) to become positively charged and the collector electrode (704) to become negatively charged. Accordingly, the thermal energy harvesting thermionic device (700) generates an electron flow (714) that is transmitted from the emitter electrode (702) to the collector electrode (704).
The emitter electrode (702) may be manufactured with a first backing (716), which may comprise, for example, a polyester film, e.g., Mylar®, and a first layer (718) extending beneath the first backing (716). The first layer (718) may be comprised, for example, graphene, platinum (Pt), or other suitable materials. In an embodiment, the emitter electrode (702) has an emitter electrode thickness measurement (720) extending in the Y direction that is, for example, approximately 0.25 millimeters (mm), such measurement being non-limiting, or in a range of, for example, about 2 nm to about 0.25 mm, such measurements being non-limiting. The first backing (716) is shown in
In an exemplary embodiment, prior to assembly, the first layer (718) is sprayed onto the first backing (716) so as to embody the first layer (718) as a nanoparticle layer that is approximately 2 nm (i.e., the approximate diameter of a nanoparticle), where the 2 nm value should be considered non-limiting. In an embodiment, the thickness (724) of the first layer (718) may be in a range of, for example, about 1 nm to about 20 nm, or about 2 nm to about 20 nm. In another embodiment, the thickness (724) of the first layer (718) may be in a range of, for example, 0.01 mm to 0.125 mm. Generally, smaller thicknesses have higher energy densities and less wasted energy. The first backing (716) has a first outer surface (728). The first backing (716) and the first layer (or the nanoparticle layer) (718) define a first interface (730) therebetween. The first layer (or the nanoparticle layer) (718) defines a first surface (732) facing the inter-electrode gap. Alternatively to spraying, the first layer (718) may be pre-formed and applied to the first backing layer (716), or vice versa, i.e., the first backing layer (716) applied to the first layer (718).
A first coating (734), such as cesium oxide (Cs2O), at least partially covers the first surface (732) to form an emitter surface (736) of the first electrode (702) that directly interfaces with a first spacer surface (738). Accordingly, the emitter electrode (702) of the embodiment illustrated in
In
In an embodiment, the second layer (748) is sprayed on to the second backing (746) to embody the second layer (748) as a second nanoparticle layer that is approximately 2 nm thick, where the 2 nm value should be considered non-limiting. The second layer measurement (754) of the second layer (748) may range from, for example, about 1 nm to about 20 nm, or about 2 nm to about 20 nm. In another embodiment, the second layer measurement (754) of the second layer (748) may be in a range of, for example, 0.01 mm to 0.125 mm. As discussed above in connection with the first layer (718), generally, smaller thicknesses have higher energy densities and less wasted energy. The second backing (746) has a second outer surface (758). The second backing (746) and the second layer/nanoparticle layer (748) define a second interface (760). The second layer (or the second nanoparticle layer) (748) defines a second surface (762) facing the inter-electrode gap. Alternatively to spraying, the second layer (748) may be pre-formed and applied to the second backing (746) or vice versa, i.e., the second backing (746) applied to the second layer (748).
A second coating (764), which may be comprised of cesium oxide (Cs2O), at least partially covers the second surface (762) to form a collector surface (766) of the collector electrode (704) that directly interfaces with a second surface (768) of the spacer (706). Accordingly, the collector electrode (704) of
In an exemplary embodiment, the first coating (734) and the second coating (764) are formed on the first and second surfaces (732) and (762), respectively. In an embodiment, an electrospray or a nano-fabrication technique is employed to form or apply the first and second coatings (734) and (764), respectively. The first and second coatings (734) and (764) can be applied in one or more predetermined patterns that may be the same as or different from one another.
In exemplary embodiments, a percentage of surface area coverage of each of the first surface (732) and second surface (762) with the respective coating layers (734) and (764) (e.g., Cs2O) is within a range of at least 50%, and up to 70%, and in at least one embodiment is about 60%. The Cs2O coatings (734) and (764) reduce the work function values of the electrodes (702) and (704) from the work function values of, for example, platinum (Pt), which is an embodiment is 5.65 electron volts (eV), and aluminum (Al), which in an embodiment is 4.28 eV. The emitter electrode (702) with the coating layer (734) of Cs2O has a work function value ranging from about 0.5 to about 2.0 eV, and in an embodiment is approximately 1.5 eV, and the collector electrode (704) with the coating layer (764) of Cs2O has a work function value of about 0.5 to about 2.0 eV, and in an embodiment is approximately 1.5 eV.
In an embodiment, the electrodes (702) and (704) are comprised of graphene, and are referred to herein as graphene electrodes (702) and (704). The graphene electrodes (702) and (704) can exhibit work function values below 1.0 eV when coated with cesium oxide, gold, tungsten, and other elements and compounds. Sulfur may be incorporated into the coatings (734) and (764) to improve the bonding of the coatings (734) and (764) to the graphene electrodes (702) and (704), respectively, particularly where the first and second layers (718) and (748) of the electrodes (702) and (704) comprise graphene and the sulfur creates covalent bonding between the electrodes (702) and (704) and their respective coatings (734) and (764). The respective work function values of the electrodes (702) and (704) can be made to differ, even when both are comprised of graphene, for example by incorporating different coatings (734) and (764) into the electrodes (702) and (704). Suitable graphene electrodes are available through ACS (Advanced Chemical Suppliers) Materials, and include Trivial Transfer Graphene™ (TTG 10055).
In an embodiment, the surface area coverage on the emitter electrode (702) or the collector electrode (704) with Cs2O is spatially resolved, e.g., applied in a pattern or non-uniform across the length of the corresponding surface, and provides a reduction in a corresponding work function to a minimum value. In an exemplary embodiment, the work function value, from a maximum of about 2.0 eV is reduced approximately 60-80% corresponding to the surface coverage of the Cs2O, e.g. cesium oxide. The lower work function values of the electrodes (702) and (704) improve operation of the thermal energy harvesting thermionic device (700) as described herein.
Platinum (Pt)-coated on copper foil and aluminum (Al) materials optionally are selected for the first and second electrodes (702) and (704), respectively, due to at least some of their metallic properties, e.g., strength and resistance to corrosion, and the measured change in work function values when the thermionic emissive material of Cs2O or other materials disclosed herein is layered thereon. Alternative materials may be used, such as graphene, noble metals including, and without limitation, rhenium (Re), osmium (Os), ruthenium (Ru), iridium (Ir), rhodium (Rh), and palladium (Pd), or any combination of these metals. In addition, and without limitation, non-noble metals such as gold (Au), tungsten (W), tantalum (Ta), and molybdenum (Mo), and combinations thereof, may also be used. For example, and without limitation, tungsten (W) nanoparticles may be used rather than platinum (Pt) nanoparticles to form the first surface (732), and gold (Au) nanoparticles may be used rather than aluminum (Al) nanoparticles to form the second surface (762). Accordingly, the selection of the materials used to form the nanoparticle surfaces (732) and (762) can be principally based on the work functions of the electrodes (702) and (704), and more specifically, the difference in the work functions once the electrodes (702) and (704) are fully fabricated.
The selection of the first and second coatings (734) and (764), e.g., thermionic electron emissive material, on the first surface (732) and second surface (762), respectively, may be partially based on the desired work function value of the electrodes (702) and (704), respectively, and chemical compatibility between the deposited materials, and the deposited thermionic electron emissive materials of the first and second coatings (734) and (764), respectively. Deposition materials include, but are not limited to, thorium, aluminum, cerium, and scandium, as well as oxides of alkali or alkaline earth metals, such as cesium, barium, calcium, and strontium, as well as combinations thereof and combinations with other materials. In at least one embodiment, the thickness of the layer of patterned thermionic electron emissive material of the first and second coatings (734) and (764) is approximately 2 nm, where the 2 nm value should be considered non-limiting. Accordingly, the electrodes (702) and (704) have highly desirable work functions.
Exemplary electrospray and nano-fabrication technique(s) and associated equipment, including three-dimensional printing and four-dimensional printing (in which the fourth dimension is varying the nanoscale composition during printing to tailor properties) for forming the first layer/first nanoparticle layer (718), the second layer/second nanoparticle layer (748), the spacer (706) and other layers and coatings discussed herein, including those of the device (700), are set forth in U.S. Application Publication No. 2015/0251213. Generally, that application publication discloses a composition including a nano-structural material, grain growth inhibitor nanoparticles, and at least one of a tailoring solute or tailoring nanoparticles. Any one or more of those compositional components (e.g., grain growth inhibitors) may be excluded from the embodiments described herein.
A simplified diagram of an electrospray apparatus or system is generally designated by reference numeral (1700) in
The spacer (800) includes a plurality of interconnected edges (802). The edges (802) have a thickness or edge measurement (804) in the range of, for example, about 2.0 nm to about 0.25 mm. In the illustrated embodiment, the interconnected edges (802) collectively define a plurality of hexagonal apertures, also referred to herein as cavities (806), in a honeycomb array (808). The cavities (806) extend in a direction parallel to the Y-axis. The spacer (800) may be configured as a uniform or relatively uniform layer, e.g., contiguous and with or without limited apertures. The apertures or cavities, either uniformly or non-uniformly provided across the width and/or length of the spacer material, may be in a range of, for example, greater than 0 mm (e.g., 2 nm) to about 0.25 mm in the Y-axis direction, similar to an embodiment of the spacer (706) of
Referring to
Referring to
The spacers (800) and (870), shown in
As shown in
With respect to the first electrode (862), the first lateral side edge (830) extends in the lateral direction Z beyond the first lateral support side edge (814) of the spacer (800), (870) by a third distance (836), and the second lateral support side edge (816) of the spacer (800), (870) extends in the lateral direction Z beyond the second lateral side edge (832) by a fourth distance (828).
With respect to the second electrode (864), the first lateral support side edge (814) of the spacer (800), (870) extends in the lateral direction Z beyond the third lateral side edge (840) by a fifth distance (826), and the fourth lateral side edge (842) extends in the lateral direction Z beyond the second lateral support side edge (816) of the spacer (800), (870) by a sixth distance (848).
In embodiments, the third distance (836), the fourth distance (828), the fifth distance (826), and the sixth distance (848) may be the same or different from one another and within a range of, for example, approximately 1.1 nm to approximately 10 microns. The spacer (800), (870) may have a lateral measurement (818) with respect to the Z-axis greater than lateral measurements (834) and (844) of the electrodes (862) and (864), respectively. The spacer design and measurements shown and described herein reduce a potential for electrodes, such as the electrodes (702) and (704), to contact one another when the spacer (800), (870) is incorporated into the device (700) of
Each of the lateral support side edges (814) and (816) may receive at least one layer of an electrically insulating sealant that electrically isolates the portions (850) and (852) of the electrodes (862) and (864), respectively, that extend beyond the lateral support side edges (814) and (816), respectively. Further, as described above, each of the electrodes (862) and (864) may be offset from the spacer (800), (870) to reduce the potential for the electrodes (862) and (864) contacting each other and creating a short circuit.
In exemplary embodiments, the at least one spacer (800) and/or (870), which in exemplary embodiments are dielectric spacers, as shown and described in
Referring to
At least one layer of a dielectric coating (910), such as a monolayer of alkanethiol material, is deposited on the Au nanoparticle clusters (904) and the Ag nanoparticle clusters (906) to form a dielectric barrier thereon. In an exemplary embodiment, the deposit of the dielectric coating (910) is performed via electrospray. The alkanethiol material of the dielectric coating (910) includes, but is not limited to, dodecanethiol and/or decanethiol. Additionally or alternatively, the dielectric coating (910) may be a halogenoalkane or alkyl halide, in which one or more of the hydrogen atoms of the alkane are replaced by halogen atom(s), i.e., fluorine, chlorine, bromine, or iodine. The deposit of the dielectric coating (910), such as alkanethiol, reduces coalescence of the nanoparticle clusters (904) and (906). In at least one embodiment, the nanoparticle clusters (904) and (906) have a diameter in the range of about 1 nm to about 3 nm. In an exemplary embodiment, the nanoparticle clusters (904) and (906) have a diameter of about 2 nm. In an exemplary embodiment, the Au nanoparticle clusters (904) and the Ag nanoparticle clusters (906) are tailored to be electrically conductive with charge storage features (i.e., capacitive features), minimize heat transfer through associate spacer apertures, such as the spacer apertures (806) of
The Au nanoparticle clusters (904) according to exemplary embodiments are dodecanethiol functionalized gold nanoparticles. In exemplary embodiments, the AU nanoparticle clusters (904) have an average particle size of about 1 nm to about 3 nm, at about 2% (weight/volume (grams/ml)). According to exemplary embodiments, the Ag nanoparticle clusters (906) are dodecanethiol functionalized silver nanoparticles. In certain embodiments, the Ag nanoparticle clusters (906) have an average particle size of about 1 nm to about 3 nm, at about 0.25% (weight/volume percent). In an embodiment, the average particle size of both the Au and Ag nanoparticle clusters (904) and (906) is at or about 2 nm. The Au and Ag cores of the nanoparticle clusters (904) and (906) are selected for their abilities to store and transfer electrons. In an embodiment, a 50%-50% mixture of Au and Ag nanoparticle clusters (904) and (906) are used. However, a mixture in the range of 1-99% Au-to-Ag could be used as well. Electron transfers are more likely to occur between nanoparticle clusters (904) and (906) with different work functions. In an exemplary embodiment, a mixture of nearly equal (molar) numbers of two different nanoparticle clusters (904) and (906), e.g., Au and Ag, provides good electron transfer. Accordingly, nanoparticle clusters are selected based on particle size, particle material (with the associated work function values), mixture ratio, and electron affinity.
Conductivity of the nano-fluid (902) can be increased by increasing concentration of the nanoparticle clusters (904) and (906). The nanoparticle clusters (904) and (906) may have a concentration within the nano-fluid (902) of, for example, about 0.1 mole/liter to about 2 moles/liter. In at least one embodiment, the Au and Ag nanoparticle clusters (904) and (906) each have a concentration of at least 1 mole/liter. In at least one embodiment, a plurality of Au and Ag nanoparticle clusters (904) and (906) are mixed together in a dielectric medium (908) to form a nano-fluid (902), the nano-fluid (902) residing in, for example, the apertures (708) of
The stability and reactivity of colloidal particles, such as Au and Ag nanoparticle clusters (904) and (906), are determined largely by a ligand shell formed by the alkanethiol coating (910) adsorbed or covalently bound to the surface of the nanoparticle clusters (904) and (906). The nanoparticle clusters (904) and (906) tend to aggregate and precipitate, which can be prevented by the presence of a ligand shell of the non-aggregating polymer alkanethiol coating (910) enabling these nanoparticle clusters (904) and (906) to remain suspended. Adsorbed or covalently attached ligands can act as stabilizers against agglomeration and can be used to impart chemical functionality to the nanoparticle clusters (904) and (906). Over time, the surfactant nature of the ligand coatings is overcome and the lower energy state of agglomerated nanoparticle clusters is formed. Over time, agglomeration may occur due to the lower energy condition of nanoparticle cluster accumulation and occasional addition of a surfactant may be used. Examples of surfactants include, without limitation, Tween® 20 and Tween® 21.
In the case of the nano-fluid (902) of
Thermally-induced Brownian motion causes the nanoparticle clusters (904) and (906) to move within the dielectric medium (908), and during this movement the nanoparticle clusters (904) and (906) occasionally collide with each other and with the electrodes (702) and (704). As the nanoparticle clusters (904) and (906) move and collide within the dielectric medium (908), the nanoparticle clusters (904) and (906) chemically and physically transfers charge. The nanoparticle clusters (904) and (906) transfer charge chemically when electrons (912) hop between electrodes, e.g., from and to the electrodes (702) and (704) of
The nanoparticle clusters (904) and (906) transfer charge physically (i.e., undergo transient charging) due to the ionization of the nanoparticle clusters (904) and (906) upon receipt of an electron, and the electric field generated by the differently charged electrodes (702) and (704). The nanoparticle clusters (904) and (906) become ionized in collisions when they gain or lose an electron (912). Positive and negative charged nanoparticle clusters (904) and (906) in the nano-fluid (902) migrate to the negatively charged collector electrode (704) and the positively charged emitter electrode (702), respectively, providing an electrical current flow. This ion current flow is in the opposite direction from the electron current flow, but less in magnitude than the electron flow.
Some ion recombination in the nano-fluid (902) may occur, which diminishes both the electron and ion current flow. Electrode separation may be selected at an optimum width (or thickness in the Y direction in
In an exemplary embodiment, when the emitter electrode (702) and the collector electrode (704) are initially brought into close proximity, the electrons of the collector electrode (704) have a higher Fermi level than the electrons of the emitter electrode (702) due to the lower work function of the collector electrode (704). The difference in Fermi levels drives a net electron current that transfers electrons from the collector electrode (704) to the emitter electrode (702) until the Fermi levels are equal, i.e., the electrochemical potentials are balanced and thermodynamic equilibrium is achieved. The transfer of electrons between the emitter electrode (702) and the collector electrode (704) results in a difference in charge between the emitter electrode (702) and the collector electrode (704). This charge difference sets up the voltage of the contact potential difference and an electric field between the emitter electrode (702) and the collector electrode (704), where the polarity of the contact potential difference is determined by the material having the greatest work function. With the Fermi levels equalized, no net current will flow between the emitter electrode (702) and the collector electrode (704). Accordingly, electrically coupling the emitter electrode (702) and the collector electrode (704) with no external load results in attaining the contact potential difference between the electrodes (702) and (704) and no net current flow between the electrodes (702) and (704) due to attainment of thermodynamic equilibrium between the two electrodes (702) and (704).
The thermal energy harvesting thermionic device (700) can generate electric power (e.g., at room temperature) with or without additional heat input. Heat added to the emitter electrode (702) will raise the temperature of the emitter electrode (702) and the Fermi level of the emitter electrode (702) electrons. With the Fermi level of the emitter electrode (702) higher than the Fermi level of the collector electrode (704), a net electron current will flow from the emitter electrode (702) to the collector electrode (704) through the nano-fluid (712), (902). If the device (700) is placed into an external circuit, such that the external circuit is connected to the electrodes (702) and (704), the same amount of electron current will flow through the external circuit from the collector electrode (704) to the emitter electrode (702). Heat energy added to the emitter electrode (702) is carried by the electrons (912) to the collector electrode (702). The bulk of the added energy is transferred to the external circuit for conversion to useful work, some of the added energy is transferred through collisions of the nanoparticle clusters (904) and (906) with the collector electrode (704), and some of the added energy is lost to ambient as waste energy. As the energy input to the emitter electrode (702) increases, the temperature of the emitter electrode (702) increases, and the electron transmission from the emitter electrode (702) increases, thereby generating more electron current. As the emitter electrode (702) releases electrons onto the nanoparticle clusters (904) and (906), energy is stored in the thermal energy harvesting thermionic device (700). Accordingly, the thermal energy harvesting thermionic device (700) generates, stores, and transfers charge and moves heat energy associated with a temperature difference, where added thermal energy causes the production of electrons to increase from the emitter electrode (702) into the nano-fluid (712), (902).
The nano-fluid (902) can be substituted into the device (700) of
As the electrons (912) hop from nanoparticle cluster (904) and (906) to nanoparticle cluster (904) and (906), single electron charging effects that include the additional work required to hop an electron (912) onto a nanoparticle cluster (904) and (906) if an electron (912) is already present on the nanoparticle cluster (904) and (906), determine if hopping additional electrons (912) onto that particular nanoparticle cluster (904) and (906) is possible. Specifically, the nanoparticle clusters (904) and (906) include a voltage feedback mechanism that prevents the hopping of more than a predetermined number of electrons to the nanoparticle cluster (904) and (906). This prevents more than the allowed number of electrons (912) from residing on the nanoparticle cluster (904) and (906) simultaneously. In an embodiment, only one electron (912) is permitted on any nanoparticle cluster (904) and (906) at any one time. Therefore, during conduction of current through the nano-fluid (902), a single electron (912) hops onto the nanoparticle cluster (904) and (906). The electron (912) does not remain on the nanoparticle cluster (904) and (906) indefinitely, but hops off to either the next nanoparticle cluster (904) and (906) or the collector electrode (704) through collisions resulting from the Brownian motion of the nanoparticle clusters (904) and (906). However, the electron (912) does remain on the nanoparticle cluster (904) and (906) long enough to provide the voltage feedback required to prevent additional electrons (912) from hopping simultaneously onto the nanoparticle clusters (904) and (906). The hopping of electrons (912) across the nanoparticle clusters (904) and (906) avoids resistive heating associated with current flow in a media. Notably, the thermal energy harvesting thermionic device (700) containing the nano-fluid (902) does not require pre-charging by an external power source in order to introduce electrostatic forces. This is due to the device (700) being self-charged with triboelectric charges generated upon contact between the nanoparticle clusters (904) and (906) due to Brownian motion. Accordingly, the electron hopping across the nano-fluid (902) is limited to one electron (912) at a time residing on a nanoparticle cluster (904) and (906).
As the electron current starts to flow through the nano-fluid (902), a substantial energy flux away from the emitter electrode (702) is made possible by the net energy exchange between emitted and replacement electrons (912). The replacement electrons from an electrical conductor connected to the emitter electrode (702) do not arrive with a value of energy equivalent to an average value of the Fermi energy associated with the material of emitter electrode (702), but with an energy that is lower than the average value of the Fermi energy. Therefore, rather than the replacement energy of the replacement electrons being equal to the chemical potential of the emitter electrode (702), the electron replacement process takes place in the available energy states below the Fermi energy in the emitter electrode (702). The process through which electrons are emitted above the Fermi level and are replaced with electrons below the Fermi energy is sometimes referred to as an inverse Nottingham effect. Accordingly, a low work function value of, for example, about 0.5 eV for the emitter electrode (702) allows for the replacement of the emitted electrons with electrons with a lower energy level to induce a cooling effect on the emitter electrode (702).
As described this far, the principal electron transfer mechanism for operation of the device (700) is thermionic energy conversion or harvesting. In some embodiments, thermoelectric energy conversion is conducted in parallel with the thermionic energy conversion. For example and referring to
A plurality of thermal energy harvesting thermionic devices (700) is distinguished by at least one embodiment having the thermoelectric energy conversion features described herein. The nano-fluid (712), (902) is selected for operation of the thermal energy harvesting thermionic devices (700) within one or more temperature ranges. In an embodiment, the temperature range of the associated thermal energy harvesting thermionic device (700) is controlled to modulate a power output of the device (700). In general, as the temperature of the emitter electrode (702) increases, the rate of thermionic emission therefrom increases. The operational temperature ranges for the nano-fluid (902) are based on the desired output of the thermal energy harvesting thermionic device (700), the temperature ranges that optimize thermionic conversion, the temperature ranges that optimize thermoelectric conversion, and fluid characteristics. Therefore, different embodiments of the nano-fluid (902) are designed for different energy outputs of the device (700).
For example, in an embodiment, the temperature of the nano-fluid (712), (902) is maintained at less than 250° C. to avoid deleterious changes in energy conversion due to the viscosity changes of the dielectric medium (908) above 250° C. In an embodiment, the temperature range of the nano-fluid (902) for substantially thermionic emission is only approximately room temperature (i.e., about 20° C. to about 25° C.) up to about 70-80° C., and the temperature range of the nano-fluid (902) for thermionic and thermo-electric conversion is above 70-80° C., with the principal limitations being the temperature limitations of the materials. In an exemplary embodiment, the nano-fluid (902) for operation including thermoelectric conversion includes a temperature range that optimizes the thermoelectric conversion through optimizing the power density within the thermal energy harvesting thermionic device (700), thereby optimizing the power output of the device (700). In at least one embodiment, a mechanism for regulating the temperature of the nano-fluid (902) includes diverting some of the energy output, e.g., heat, of the device (700) into the nano-fluid (902). Accordingly, the apertures (708) of specific embodiments of the thermal energy harvesting thermionic device (700) may be filled with the nano-fluid (902) to employ thermoelectric energy conversion with thermionic energy conversion above a particular temperature range, or thermionic energy conversion by itself below that temperature range.
As described herein, in at least one embodiment, the dielectric medium (908) has thermal conductivity values less than about 1.0 watt per meter-Kelvin (W/m·K). In at least one embodiment, the thermal conductivity of the dielectric medium (908) is about 0.013 watt per meter-Kelvin (W/m·K), as compared to the thermal conductivity of water at about 20 degrees Celsius (° C.) of about 0.6 W/m·K. Accordingly, the nano-fluid (902) minimizes heat transfer, such as through the apertures (708) of
As shown in
Examples of a first factor include, but are not limited to, enhanced phonon and electron transfer between the plurality of nanoparticle clusters (904) and (906) within the nano-fluid (902), enhanced phonon and electron transfer between the plurality of nanoparticle clusters (904) and (906) and the first electrode (702), and enhanced phonon and electron transfer between the plurality of nanoparticle clusters (904) and (906) and the second electrode (704).
A second factor is an enhanced influence of Brownian motion of the nanoparticle clusters (904) and (906) in a confining environment between the electrodes (702) and (704) to, e.g., less than about 10 nm inter-electrode distance (710). As the distance (710) between the electrodes (702) and (704) decreases below about 10 nm, fluid continuum characteristics of the nano-fluid (712), (902) with the suspended nanoparticle clusters (904) and (906) is altered. For example, as the ratio of particle size to volume of the apertures (708) increases, random and convection-like effects of Brownian motion in a dilute solution dominate. Therefore, collisions of the nanoparticle clusters (904) and (906) with the surfaces of other nanoparticle clusters (904) and (906) and the electrodes (702) and (704) increase thermal and electrical conductivity values due to the enhanced phonon and electron transfer.
A third factor is the at least partial formation of matrices of the nanoparticle clusters (904) and (906) within the nano-fluid (902). Under certain conditions, the nanoparticle clusters (904) and (906) will form matrices within the nano-fluid (902) as a function of close proximity to each other with some of the nanoparticle clusters (908) remaining independent from the matrices. In an embodiment, the formation of the matrices is based on the factors of time and/or concentration of the nanoparticle clusters (904) and (906) in the nano-fluid (902).
A fourth factor is the predetermined nanoparticle clusters (904) and (906) density, which in an embodiment is about one mole per liter. Accordingly, apertures (708) containing the nano-fluid (902) with a distance (710) of about 1 nm to less than about 10 nm causes an increase in the thermal and electrical conductivity values of the nano-fluid (902) therein.
In addition, the nanoparticle clusters (904) and (906) have a small characteristic length, e.g., about 2 nm, and the clusters (904) and (906) are often considered to have only one dimension. This characteristic length restricts electrons in a process called quantum confinement, which increases electrical conductivity. The collision of particles with different quantum confinement facilitates transfer of charge to the electrodes (702) and (704). The thermal energy harvesting thermionic device (700) has an enhanced electrical conductivity value greater than about 1 Siemens per meter (S/m) as compared to the electrical conductivity of drinking water of about 0.005 S/m to about 0.05 S/m. Also, the embodiments of the device (700) with the enhanced thermal conductivity have a thermal conductivity value greater than about 1 W/m·K as compared to the thermal conductivity of water at 20 degrees Celsius (° C.) of about 0.6 W/m·K.
Thermionic emission of electrons (912) from the emitter electrode (702) and the transfer of the electrons (912) across the nano-fluid (902) from one nanoparticle cluster (904) and (906) to another nanoparticle cluster (904) and (906) through hopping are both quantum mechanical effects.
Release of electrons from the emitter electrode (702) through thermionic emission as described herein is an energy selective mechanism. A thermionic barrier in the apertures (708) between the emitter electrode (702) and the collector electrode (704) is induced through the interaction of the nanoparticles (904) and (906) inside the apertures (708) with the electrodes (702) and (704). The thermionic barrier is at least partially induced through the number and material composition of the plurality of nanoparticle clusters (904) and (906). The thermionic barrier induced through the nano-fluid (902) provides an energy selective barrier on the order of magnitude of about 1 eV. Accordingly, the nano-fluid (902) provides an energy selective barrier to electron emission and transmission.
To overcome the thermionic barrier and allow electrons (912) to be emitted from the emitter electrode (702) above the energy level needed to overcome the barrier, materials for the emitter electrode (702) and the collector electrode (704) are selected for their work function values and Fermi level values. The Fermi levels of the two electrodes (702) and (704) and the nanoparticle clusters (904) and (906) will try to align by tunneling electrons (912) from the electrodes (702) and (704) to the nanoparticle clusters (904) and (906). The difference in potential between the two electrodes (702) and (704) (described elsewhere herein) overcomes the thermionic barrier, and the thermionic emission of electrons (912) from the emitter electrode (702) occurs with sufficient energy to overcome the thermionic block. Notably, and in general, for cooling purposes, removing higher energy electrons from the emitter electrode (702) causes the emission of electrons (912) to carry away more heat energy from the emitter electrode (702) than is realized with lower energy electrons. Accordingly, the energy selective barrier is overcome through the thermionic emission of electrons at a higher energy level than would be otherwise occurring without the thermionic barrier.
Once the electrons (912) have been emitted from the emitter electrode (702) through thermionic emission, the thermionic barrier continues to present an obstacle to further transmission of the electrons (912) through the nano-fluid (902). Smaller inter-electrode gaps on the order of about 1 nm to about 10 nm, as compared to those gaps in excess of 100 nm, facilitate electron hopping, i.e., field emission, of short distances across the apertures (708). Energy requirements for electron hopping are much lower than the energy requirements for thermionic emission; therefore, the electron hopping has a significant effect on the energy generation characteristics of the device (700). The design of the nano-fluid (902) enables energy selective tunneling, e.g., electron hopping, that is a result of the barrier (which has wider gap for low energy electrons) which results in electrons above the Fermi level being a principal hopping component. In an exemplary embodiment, direction of the electron hopping is determined through the selection of the different materials for the electrodes (702) and (704) and their associated work function and Fermi level values. The electron hopping across the nano-fluid (902) transfers heat energy with electrons (912) across the apertures (708) while maintaining a predetermined temperature gradient such that the temperature of the nano-fluid (902) is relatively unchanged during the electron transfer. Accordingly, the emitted electrons transport heat energy from the emitter electrode (702) across the apertures (708) to the collector electrode (704) without increasing the temperature of the nano-fluid (902).
In an embodiment, the thermal energy harvesting thermionic device (700) is configurable with respect to the physical dimensions therein. In an exemplary embodiment, the device (700) has a length measurement, in a direction along the X-axis in
Referring to
The thermal energy harvesting thermionic device (1090) is shown herein with an at least partially planar configuration with a defined radius (1012) extending from an end of an aperture (1018) to an outermost surface (1016) of the device (1090). It should be understood that various configurations may be practiced. As shown herein, the aperture (1018) has a planar or relatively planar geometric characteristic, and is hereinafter referred to as a planar aperture or slot. The planar aperture (1018) has geometric properties, including a first end area (1020) and an opposing second end area (1022), with the planar aperture extending (along a direction parallel to axis Z) from the first end area (1020) to the second end area (1022). In an embodiment, the distance between the first end area (1020) and the second end area (1022) is referred to as a first distance.
In an embodiment, a structural member (1024) is inserted into, received by, and positioned within the planar aperture (1018). In an embodiment, the structural member (1024) received by and positioned in the aperture (1018) extends beyond the area defined by the aperture (1018). In an embodiment, the structural member (1024) is fabricated from one or more materials that are both thermally and electrically conductive, as well as chemically compatible with the materials of the layers (1002), (1004), (1006), and (1008). In other embodiments, the structural member (1024) is fabricated from materials that are either thermally or electrically conductive. Accordingly, the structural member (1024) is configured with mechanical and electrical properties. Although the structural member (1024) is illustrated as a flat, e.g., planar, plate, it should be understood that the structural member (1024) may have other configurations.
The fourth layer (1008), i.e., the collector electrode, is electrically coupled to the structural member (1024) to provide at least a partial electrical flow path. The composite sheet (1010) extends from the structural member (1024) in a wrapped or rolled configuration, where the wrapped configuration has a common center defined by the planar aperture (1018) to further define a concentric configuration. The planar aperture (1018) imparts a toroidal configuration to the wrapped configuration of the composite sheet (1010). Accordingly, the at least partially planar thermal energy harvesting thermionic device (1090) has characteristics that are substantially toroidal.
In an embodiment, the thermal energy harvesting thermionic device (1090) has a first measurement (1026), referred to as length, of approximately 10 mm to about 2.0 m. Lengths outside this range are contemplated. A thickness of the composite layer (1010) (i.e., collective thickness of the layers (1002), (1004), (1006), and (1008)) is approximately 0.005 mm to about 2.0 mm. A thickness (1030) of the collector electrode (1008) is, for example, approximately 0.005 mm to less than 2.0 mm. A thickness (1032) of the spacer (1006) is, for example, approximately 1.0 nm to about 10 microns. A thickness (1034) of the emitter electrode (1004) is, for example, approximately 0.005 mm to less than 2.0 mm. A thickness (1036) of the outer casing (1002) is, for example, approximately 0.005 mm to less than 2.0 mm. The composite sheet (1010) is defined by a first measurement, which is referred to as a composite length, ranging from approximately 10 mm to 2.0 m, for example. Other embodiments include any dimensional characteristics that enable operation of the thermionic device (1090) as described herein.
As further shown, an electrical circuit (1050) is connected to the thermal energy harvesting thermionic device (1090). The circuit (1050) includes an electrical conductor (1052) that is electrically connected to the structural member (1024) that is electrically connected to the collector electrode (1008). The circuit (1050) further includes at least one electrical load (1056), such as a power-consumption device or a rechargeable power storage device (or the appliance) connected to the conductor (1052). When the thermal energy harvesting thermionic device (1090) is generating electricity, electrical current (1058) (using conventional flow notation) is transmitted through the circuit (1050) in an opposite direction to the electron current. As discussed above, the electrons flow within the device (1090) from the emitter electrode (1004) to the collector electrode (1008), then through the load (1056) back to the emitter electrode (1004). For example, a single device (1090) can generate a voltage within a range extending between about 0.5 volt and 1.0 volt, depending on the contact potential difference (discussed further herein) induced between the emitter electrode (1004) and the collector electrode (1008) as a function of the emitted and collector materials. In an embodiment, the device (1090) generates about 0.90 volt. In an embodiment, the device (1090) can generate an electrical current within a range of approximately 5 amperes (amps) to approximately 10 amps. In an embodiment, the device (1090) generates about 7.35 amps. Further, in an embodiment, the device (1090) generates approximately 2.5 watts to approximately 10 watts. In an embodiment, the device (1090) generates about 6.6 watts. A plurality of the devices (1090) may be electrically connected in series for a specific voltage or in parallel for a specific current, or in series and parallel to satisfy voltage, current, and power requirements. Accordingly, as described further herein, an arrangement of the devices (1090) is scalable to provide sufficient electrical power from the watt range to the megawatt range for a variety of applications.
The structural member (1024) performs both heat transfer and electrical conduction actions when the thermal energy harvesting thermionic device (1090) is in service generating electricity. The structural member (1024) is electrically coupled to the circuit (1050) to transmit the electrical power generated within the device (1090) along the conductor (1052) to the electrical load (1056).
In the embodiment shown in
The thermal energy harvesting thermionic device (1090) generates electric power through harvesting heat energy (1064). As described in further detail herein, the emitter electrode (1004) receives heat energy (1064) from an appliance (e.g., (104), (204), (304), or (402) of
In
Referring to
A first end or base area (1120) receives a sealant (1146) that extends between a rim (1148) defined by the outer casing (1102) and a structural member (1124), which is the same as or similar to the structural member (1024) described above. In an embodiment, the sealant (1146) is substantially similar to the sealant (1144) with respect to composition and function. In an embodiment, the sealant (1146) is different from the sealant (1144). The sealant (1146) is also applied to a second end or base area (1122), oppositely disposed from the first end area (1120). In an embodiment, the second end area (1122) has a similar configuration to the first end area (1120). The sealant (1146) functions to protect electrodes (e.g., the electrodes (1004) and (1008)), spacer (e.g., the spacer (1006)), and nano-fluid (e.g., the nano-fluid (902)) from environmental factors, such as debris, that may induce a short circuit between electrodes (e.g., the electrodes (1004) and (1008)) or contaminate the nano-fluid (902).
In addition, as described herein with respect to
In an embodiment, the thermal energy harvesting thermionic device (700) is manufactured from different prefabricated materials.
Referring to
Referring to
In an embodiment, rather than manufacturing the thermal energy harvesting thermionic device using the two repositories or rolls (1200) and (1300), each of the layers (1202), (1204), (1306), and (1308) are dispensed from an individual repository or roll for each layer. In another embodiment, rather than using a separation material (1306) in the form of a solid material, the separation material (1306) is applied to either the second surface (1276) of the emitter electrode (1204) or the first surface (1374) of the collector electrode (1308). In an embodiment, the solid material is a sheet or a web. In an embodiment, the separation material (1306) is applied to both of the surfaces (1276) and (1374). In an embodiment, the separation material (1306) is pre-applied to the electrodes (1204) and (1308). In an embodiment, the separation material (1306) is applied to the electrodes (1204) and (1308) at the time of manufacture of the thermal energy harvesting thermionic device. In an embodiment, the separation material (1306) is a fluid applied through one or more electrospray devices (e.g.,
Referring to
The first (top) harvester unit (1501A) includes an emitter electrode (cathode) (1502A) having a coating (1534A), a collector electrode (anode) (1504A) having a coating (1564A), and a chamber (or aperture) interposed between the electrodes (1502A) and (1504A) filled with nano-fluid (1508A) and surrounded on opposite sides by insulating spacers (1506A1) and (1506A2). The second (middle) harvester unit (1501B) includes an emitter electrode (cathode) (1502B) having a coating (1534B), a collector electrode (anode) (1504B) having a coating (1564B), and a chamber (or aperture) between the electrodes (1502B) and (1504B) filled with nano-fluid (1508B) and surrounded on opposite sides by insulating spacers (1506B1) and (1506B2). The third (bottom) harvester unit (1501C) includes an emitter electrode (cathode) (1502C) having a coating (1534C), a collector electrode (anode) (1504C) having a coating (1564C), and a chamber (or aperture) between the electrodes (1502C) and (1504C) filled with nano-fluid (1508C) and surrounded on opposite sides by insulating spacers (1506C1) and (1506C2).
A first insulating layer (1570A) is positioned above the first harvester unit (1501A). A second insulating layer (1570B) is interposed between the first harvester unit (1501A) and the second harvester unit (1501B). A third insulating layer (1570C) is interposed between the second harvester unit (1501B) and the third harvester unit (1501C). A conductive plate (1572) is positioned below the third harvester unit (1501C) as a thermal conductor for transmitting heat from the heat generating source (e.g., the appliance (104) of
The emitter electrodes (cathodes) (1502A), (1502B), and (1502C) may be made of any of the materials described herein. In an exemplary embodiment, the emitter electrodes (1502A), (1502B), and (1502C) are made of a copper foil coated with platinum (Pt). The emitter electrode coatings (1534A), (1534B), and (1534C) may be comprised of cesium oxide. The emitter electrode coatings (1534A), (1534B), and (1534C) may cover, for example, about 60 to 80 percent of the surface area of their respective emitter electrodes. The collector electrodes (anodes) (1504A), (1504B), and (1504C) likewise may be made of any of the materials described herein. In an exemplary embodiment, the collector electrodes (1504A), (1504B), and (1504C) are made of tungsten foil. The collector electrode coatings (1564A), (1564B), and (1564C) may be comprised of cesium oxide. The collector electrode coatings (1564A), (1564B), and (1564C) may cover, for example, about 60 to about 80 percent of the surface area of their respective collector electrodes.
The nano-fluids (1508A), (1508B), and (1508C) may be, for example, any of the materials described above in connection with
The insulating spacers (1506A1), (1506A2), (1506B1), (1506B2), (1506C1), and (1506C2) and the insulating layers (1570A), (1570B), and (1570C) may be comprised of, for example, an alkane-thiol. The spacers may have a multi-layer (e.g., five-layer) structure, with each layer at least one micron in thickness.
For the purposes of illustration, the thermal energy harvesting thermionic device (1500) has been shown with three thermionic units (1501A), (1501B), and (1501C) stacked on one another. It should be understood that the device (1500) may include fewer (two) or more thermionic units than shown. Although
Referring to
An appliance is positioned proximal to the thermal energy harvesting thermionic device (1610). See
As described herein, exemplary embodiments are directed generally to an apparatus including an energy source, and more particularly is directed to a thermal energy harvesting thermionic device. Ionization is provided therein by the combination of electron tunneling and thermionic emission of the thermal energy harvesting thermionic device. Charge transfer therein is affected through conductive nanoparticles suspended in a fluid, i.e., a nano-fluid, undergoing collisions driven by thermally-induced Brownian motion. The design of the thermal energy harvesting thermionic device enables energy extraction from the heat generating source of the apparatus. To this end, the electrodes are proximally positioned to allow electrons to travel the distance between them. These electrons emitted at a wide range of temperatures proceed across the gap due to the nano-fluid providing a conductive pathway for the electron emission, reducing or minimizing heat transfer to maintain a nano-scale heat engine, and preventing arcing.
With respect to thermionic converters, the electrical efficiency of exemplary embodiments of these devices depends on low work function materials deposited on the emitter electrode (cathode) and the collector electrode (anode). The efficiency of two low work function value electrodes can be increased by developing cathodes with sufficient thermionic emission of electrons operating even at room temperature. These low work function cathodes and anodes provide copious amounts of electrons. Similarly, a tunneling device includes two low work function electrodes separated by a designed nano-fluid. Cooling by electrode emission refers to the transport of hot electrons across the nano-fluid gap, from the object to be cooled (cathode) to the heat rejection electrode (anode). Thus, exemplary embodiments involve coupling of several technologies, including: the electrospray-deposited two low work function electrodes including, for example, cesium-oxide on both electrode surfaces; an energy selective electron-transfer thermionic emission and quantum hopping of electrons; a nano-fluid that is tailored as a thermoelectric element to conduct electricity while minimizing heat transfer within the device; and thermal communication from the anode electrical connection that is in thermal contact with the device and the heat dissipating device, such as a heat sink or a heat exchanger, produces a thermionic power generator according to an exemplary embodiment.
The thermal energy harvesting thermionic devices of exemplary embodiments described herein facilitate generating electrical energy via a long-lived, constantly-recharging, battery-like device for any size-scale electrical application. Thermal energy harvesting thermionic devices of exemplary embodiments have a conversion efficiency superior to presently available single and double conventional batteries. In addition, the devices of exemplary embodiments described herein may be incorporated into an apparatus for charging a secondary battery and/or powering an electrical load, such as a power-consumption device. The thermal energy harvesting thermionic devices of exemplary embodiments described herein are light weight, compact, and have a relatively long operating life with an electrical power output at a useful value. Furthermore, in addition to the tailored work functions, the nanoparticle clusters of exemplary embodiments described herein are multiphase nano-composites that include thermoelectric materials. The combination of thermoelectric and thermionic functions within a single device further enhances the power generation capabilities of the thermal energy harvesting thermionic devices.
The conversion of heat from an appliance into usable electricity enables energy harvesting capable of offsetting, or even replacing, the reliance of electronics and appliances on conventional power supplies, such as electrochemical batteries, especially when long-term operation of a large number of electronic devices in dispersed locations is required. Energy harvesting distinguishes itself from batteries and hardwire power owing to inherent advantages, such as outstanding longevity measured in years, little maintenance, and minimal disposal and contamination issues. The thermal energy harvesting thermionic devices described herein demonstrate a novel electric generator with low cost for efficiently harvesting thermal energy. The devices described herein initiate electron flow due to the differences in the Fermi levels of the electrodes without the need for an initial temperature differential or thermal gradient, although in exemplary embodiments appliances are used to generate the temperature differentials over the course of use.
The thermal energy harvesting thermionic devices of exemplary embodiments described herein are scalable across a large number of power generation requirements. The devices may be designed for applications requiring electric power in the milliwatts (mW), watts (W), kilowatts (kW), and megawatts (MW) ranges.
The production of renewable, sustainable, green energy resources is the critical innovation for sustainable development of human civilization. Embodiments disclosed herein include one or more thermal energy harvesting thermionic devices operating proximal to an appliance to power electricity-consuming devices, including but not limited to the appliance. Further embodiments disclosed herein include one or more thermal energy harvesting thermionic devices operating proximal to an appliance to complement the power of a battery or other electricity-generating system (e.g., an electrical outlet of an AC source) to power electricity-consuming devices, including but not limited to the appliance. In exemplary embodiments, the thermionic device is a nanoscale energy harvester, and in further exemplary devices is the sole power supply. In an exemplary embodiment, the thermionic device can cause the appliance to be substantially autogenous or self-powered, converting heat generated by the appliance into electricity for further operation of the appliance.
Aspects of the present embodiments are described herein with reference to one or more of flowchart illustrations and/or block diagrams of methods and apparatus (systems) according to the embodiments.
While particular embodiments have been shown and described, it will be understood to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from its broader aspects. Therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the embodiments. Furthermore, it is to be understood that the embodiments are solely defined by the appended claims. It will be understood by those with skill in the art that if a specific number of an introduced claim element is intended, such intent will be explicitly recited in the claim, and in the absence of such recitation no such limitation is present. For non-limiting example, as an aid to understanding, the following appended claims contain usage of the introductory phrases “at least one” and “one or more” to introduce claim elements. However, the use of such phrases should not be construed to imply that the introduction of a claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to the embodiments containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an”; the same holds true for the use in the claims of definite articles. As used herein, the term “and/or” means either or both (or any combination or all of the terms or expressed referred to).
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present embodiments has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the embodiments. The embodiments were chosen and described in order to best explain the principles of the embodiments and the practical application, and to enable others of ordinary skill in the art to understand the embodiments for various embodiments with various modifications and combinations with one another as are suited to the particular use contemplated. Accordingly, the scope of protection of the embodiment(s) is limited only by the following claims and their equivalents.
