OPTICAL IGNITION OF FUELS
A method of combustion includes: (1) introducing microparticles and nanoparticles into a combustion chamber, where the microparticles and the nanoparticles are formed of different materials; and (2) using an optical source, irradiating the microparticles and the nanoparticles within the combustion chamber to ignite the microparticles.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/773,953 filed on Mar. 7, 2013, the disclosure of which is incorporated herein by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTThis invention was made with Government support under Grant No. W911NF-10-1-0106, awarded by the Army Research Office. The Government has certain rights in the invention.
FIELD OF THE INVENTIONThis disclosure generally relates to ignition of fuels and, more particularly, to optical ignition of fuels.
BACKGROUNDCombustion of fuels provides a driving force for a number of applications, including stationary power generation and transportation. Fuels are typically ignited by spark plugs, hot wires, and pilot flames, where chemical reactions are initiated locally and propagate to the rest of a fuel volume. Since ignition occurs at a single location, incomplete combustion can occur when there is insufficient time for reaction, such as in rockets and scramjets. In addition, combustion of fuels is desirable to generate power in microelectromechanical systems (MEMS), but the limited space available impedes the use of conventional ignition systems.
It is against this background that a need arose to develop the technique for optical ignition of fuels and related systems and methods described herein
SUMMARYDistributed, non-intrusive, and miniaturizable ignition systems are desired for controlling combustion, and for allowing integration into MEMS as power generators. Embodiments described herein are directed to a distributed, optical ignition technique that uses an optical source to ignite particles of energetic materials, resulting in the ignition of solid phase energetic materials, liquid fuels, and gaseous fuels. In some embodiments, the optical ignition occurs when the particles have suitable dimensions to cause a temperature rise above their ignition temperatures.
For example, aluminum (Al) is an attractive solid fuel for rocket propulsion and energy conversion systems due to its large volumetric energy density, earth abundance, and low cost. Non-intrusive optical flash ignition is attractive for many applications due to its simplicity and flexibility in controlling the area exposed to the flash. However, flash ignition of Al microparticles can be challenging due to their higher minimum flash ignition energy, which may originate from weaker light absorption and higher ignition temperature compared to Al nanoparticles. Herein for some embodiments, the minimum flash ignition energy of Al microparticles is reduced by the addition of metal oxide nanoparticles.
Some aspects of this disclosure are directed to a method of combustion. In some embodiments, the method includes: (1) introducing microparticles and nanoparticles into a combustion chamber, where the microparticles and the nanoparticles are formed of different materials; and (2) using an optical source, irradiating the microparticles and the nanoparticles within the combustion chamber to ignite the microparticles.
Other aspects of this disclosure are directed to a reaction device. In some embodiments, the reaction device includes: (1) a housing defining an internal chamber; (2) a reaction material disposed within the internal chamber and including microparticles and nanoparticles that are formed of different materials; and (3) an optical ignition system connected to the housing and operable to irradiate the microparticles and the nanoparticles to ignite the reaction material.
Other aspects and embodiments of this disclosure are also contemplated. The foregoing summary and the following detailed description are not meant to restrict this disclosure to any particular embodiment but are merely meant to describe some embodiments of this disclosure.
For a better understanding of the nature and objects of some embodiments of this disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.
The following definitions apply to some of the aspects described with respect to some embodiments of this disclosure. These definitions may likewise be expanded upon herein.
As used herein, the singular terms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to an object can include multiple objects unless the context clearly dictates otherwise.
As used herein, the term “set” refers to a collection of one or more objects. Thus, for example, a set of objects can include a single object or multiple objects. Objects of a set can also be referred to as members of the set. Objects of a set can be the same or different. In some instances, objects of a set can share one or more common characteristics.
As used herein, the terms “connect,” “connected,” “connecting,” and “connection” refer to an operational coupling or linking Connected objects can be directly coupled to one another or can be indirectly coupled to one another, such as through another set of objects.
As used herein, the terms “substantially” and “about” are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. For example, the terms can refer to less than or equal to ±10%, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%.
As used herein, the term “aspect ratio” refers to a ratio of a largest dimension or extent of an object and an average of remaining dimensions or extents of the object, where the remaining dimensions are orthogonal with respect to one another and with respect to the largest dimension. In some instances, remaining dimensions of an object can be substantially the same, and an average of the remaining dimensions can substantially correspond to either of the remaining dimensions. For example, an aspect ratio of a cylinder refers to a ratio of a length of the cylinder and a cross-sectional diameter of the cylinder. As another example, an aspect ratio of a spheroid refers to a ratio of a major axis of the spheroid and a minor axis of the spheroid.
As used herein, the term “size” refers to a characteristic dimension of an object. Thus, for example, a size of an object that is spherical can refer to a diameter of the object. In the case of an object that is non-spherical, a size of the non-spherical object can refer to a diameter of a corresponding spherical object, where the corresponding spherical object exhibits or has a particular set of derivable or measurable characteristics that are substantially the same as those of the non-spherical object. Thus, for example, a size of a non-spherical object can refer to a diameter of a corresponding spherical object that exhibits optical characteristics that are substantially the same as those of the non-spherical object. Alternatively, or in conjunction, a size of a non-spherical object can refer to an average of various orthogonal dimensions of the object. Thus, for example, a size of an object that is a spheroidal can refer to an average of a major axis and a minor axis of the object. When referring to a set of objects as having a particular size, it is contemplated that the objects can have a distribution of sizes around the particular size. Thus, as used herein, a size of a set of objects can refer to a typical size of a distribution of sizes, such as an average size, a median size, or a peak size.
As used herein, the term “nanostructure” refers to an object that has at least one dimension in the range of about 1 nm to about 100 nm, such as from about 1 nm to about 50 nm, from about 50 nm to about 100 nm, from about 1 nm to about 20 nm, from about 20 nm to about 100 nm, from about 1 nm to about 10 nm, or from about 10 nm to about 100 nm. A nanostructure can have any of a wide variety of shapes, and can be formed of a wide variety of materials.
As used herein, the term “nanoparticle” refers to a spherical or spheroidal nanostructure. Typically, each dimension of a nanoparticle is in the range of about 1 nm to about 100 nm, the nanoparticle has a size in the range of about 1 nm to about 100 nm, and the nanoparticle also has an aspect ratio that is less than about 5, such as no greater than about 3, no greater than about 2, no greater than about 1.5, or about 1.
As used herein, the term “microstructure” refers to an object that has at least one dimension in the range of about 100 nm to about 100 μm, such as from about 100 nm to about 500 nm, from about 500 nm to about 1 μm, from about 1 μm to about 20 μm, from about 20 μm to about 100 μm, from about 1 μm to about 5 μm, from about 5 μm to about 10 pm, from about 1 μm to about 10 μm, or from about 10 μm to about 100 μm. A microstructure can have any of a wide variety of shapes, and can be formed of a wide variety of materials.
As used herein, the term “microparticle” refers to a spherical or spheroidal microstructure. Typically, each dimension of a microparticle is in the range of about 100 nm to about 100 μm, the microparticle has a size in the range of about 100 nm to about 100 μm, and the microparticle also has an aspect ratio that is less than about 5, such as no greater than about 3, no greater than about 2, no greater than about 1.5, or about 1.
As used herein, the term “ultraviolet range” refers to a range of wavelengths from about 5 nm to about 400 nm.
As used herein, the term “visible range” refers to a range of wavelengths from about 400 nm to about 700 nm.
As used herein, the term “infrared range” refers to a range of wavelengths from about 700 nm to about 2 mm.
Optical Ignition of FuelsEmbodiments described herein provide a technique to ignite solid, liquid, and gaseous fuels in a distributed, multi-point, or homogenous fashion for combustion applications. It is desirable to have distributed ignition to reduce the time for combustion and achieve higher combustion efficiency through greater uniformity of reaction. Shorter combustion time and higher combustion efficiency are desirable for a number of applications, including rapid reciprocating engines and jet engines.
According to some embodiments, a fuel and a set of particles (either, or both, nanoparticles and microparticles) are injected separately or as a mixture into a combustion chamber, and the particles are exposed to optical energy, such as a short pulse of light. The distribution of the particles within a volume of the fuel allows chemical reactions to be initiated at multiple locations. Specifically, the particles absorb the optical energy and release it as heat, and the released heat is sufficiently high to ignite the fuel in a distributed fashion. In other embodiments, the particles can serve as the fuel itself, such that an additional fuel can be omitted.
According to some embodiments, the use of either, or both, nanoparticles and microparticles provides various advantages. Certain of these advantages derive from a higher surface to volume ratio, with the higher surface to volume ratio providing improved performance in terms of absorption of optical energy and its conversion into heat. Also, the use of either, or both, nanoparticles and microparticles allows ignition to occur without requiring an additional oxidant beyond air. Moreover, ignition can occur without relying on the presence of embedded catalysts that can translate into higher manufacturing and operational costs.
According to some embodiments, microparticles are formed of, or include, energetic materials having a high energy density that can be released as heat for ignition, such as an energy density of at least about 20 kJ/cm3, at least about 30 kJ/cm3, at least about 40 kJ/cm3, at least about 50 kJ/cm3, at least about 60 kJ/cm3, at least about 70 kJ/cm3, or at least about 80 kJ/cm3, and up to about 100 kJ/cm3, up to about 150 kJ/cm3, up to about 200 kJ/cm3, or more. Examples of such energetic materials include metals, such as alkali metals (e.g., lithium, sodium, potassium, rubidium, and cesium), alkaline earth metals (e.g., magnesium), transition metals (e.g., iron (Fe), copper (Cu), tungsten (W), and molybdenum (Mo)), post-transition metals (e.g., aluminum (Al)), lanthanides, and actinides; and alloys, oxides, hydrides, and alkoxides of such metals, such as aluminum oxide (e.g., Al2O3), iron oxide (e.g., Fe2O3), copper oxide (e.g., CuO), tungsten oxide (e.g., W03), and molybdenum oxide (e.g., MoO3). Additional examples of such energetic materials include pyrophoric materials. According to some embodiments, microparticles each include a core that is formed of, or include, an energetic material, which core is partially or fully surrounded by a shell that is formed of, or includes, the same energetic material or a different material. A thickness of the shell can be up to about 20 nm, such as up to about 15 nm, up to about 10 nm, or up to about 5 nm, and down to about 1 nm or less. In some embodiments, the core is formed of, or includes, a metal, and the shell is formed of, or includes, an oxide of the same metal or a different metal. The shell can provide a protective function, as well as serve as an oxidant during ignition.
Compared to nanoparticles, microparticles of an energetic material can be more suitable for some embodiments since they are cheaper, safer to handle, and include a higher content of the energetic material due to a smaller fraction of an inert shell. However, it can be difficult to optically ignite microparticles due to their low light absorption and high ignition temperature.
According to some embodiments, a mixture of microparticles and nanoparticles formed of, or including, different materials can be used. Specifically, the mixture can include microparticles formed of, or including, a first energetic material, along with nanoparticles formed of, or including, a second material that promotes ignition of the first energetic material, such as by providing a source of oxygen, enhancing light absorption, or both. Examples of such a mixture include a mixture of Al microparticles and nanoparticles of a metal oxide, such as WO3 nanoparticles, Fe2O3 nanoparticles, MoO3 nanoparticles, or any combination thereof. In some embodiments, a molar ratio of the second material to the first energetic material is in the range of about 1:10 to about 10:1, such as from about 1:10 to about 5:1, from about 5:1 to about 10:1, from about 1:10 to about 3:1, from about 3:1 to about 10:1, from about 1:10 to about 2:1, from about 2:1 to about 10:1, from about 1:10 to about 1:1, from about 1:1 to about 10:1, from about 1:7 to about 1:1, from about 1:5 to about 1:1, from about 1:3 to about 1:1, from about 1:10 to about 2:3, from about 1:7 to about 2:3, from about 1:5 to about 2:3, or from about 1:3 to about 2:3. In some embodiments, the second material has a bandgap energy that falls within an emission spectrum of an optical source used for flash ignition, such as within the ultraviolet range, the visible range, or the infrared range.
According to some embodiments, a mixture of microparticles and nanoparticles are ignited by an optical source through a photo-thermal effect. Suitable optical sources include pulsed sources that provide incident light with an energy density in the range of about 0.1 J/cm2 to about 100 J/cm2, such as from about 0.1 J/cm2 to about 50 J/cm2, from about 0.1 J/cm2 to about 10 J/cm2, from about 0.1 J/cm2 to about 5 J/cm2, or from about 0.1 J/cm2 to about 1 J/cm2, and a pulse duration in the range of about 0.1 ms to about 100 ms, such as from about 0.1 ms to about 50 ms or from about 0.1 ms to about 10 ms. Advantageously, the inclusion of the nanoparticles, such as nanoparticles of a metal oxide, can reduce a threshold or minimum energy density that can ignite the microparticles, such as no greater than about 1 J/cm2, no greater than about 0.95 J/cm2, no greater than about 0.9 J/cm2, no greater than about 0.85 J/cm2, no greater than about 0.8 J/cm2, no greater than about 0.75 J/cm2, no greater than about 0.7 J/cm2, no greater than about 0.65 J/cm2, no greater than about 0.6 J/cm2, no greater than about 0.55 J/cm2, no greater than about 0.5 J/cm2, no greater than about 0.45 J/cm2, no greater than about 0.4 J/cm2, or no greater than about 0.35 J/cm2. Through the photo-thermal effect, irradiation of the mixture by an optical source can yield a heating rate in the range of about 105 K/s to about 109 K/s, such as from about 105 K/s to about 108 K/s, from about 106 K/s to about 108 K/s, or from about 105 K/s to about 107 K/s. For example, an electronic flashtube, such as a xenon lamp of a camera flash unit, can be a suitable optical source. Flash ignition has the advantages of low power input, multi-point initiation, and broad emission spectrum across the ultraviolet range, the visible range, and the infrared range. Since an absorption cross-section of particles typically peaks at different wavelengths for particles of different dimensions, a broad emission spectrum can be desirable to ignite the particles having different dimensions. A light-emitting diode that emits a short duration pulse also can be used as an optical source. Other embodiments can be implemented with an optical source that provides a substantially continuous light exposure to injected particles within a combustion chamber.
Examples of applications of the optical ignition technique described herein include the incorporation of optical ignition systems in combustion engines, such as those found in cars, power plants, aircrafts, and rockets; power generators in MEMS, such as for the purposes of sensors or actuators; and reaction devices, such as explosive devices for the purposes of demolition or weaponry. For example, rapid reciprocating engines and jet engines, such as air breathing jet engines, gas turbines, turbojet engines, turbofan engines, turboprop engines, prop fan engines, ramjet engines, and scramjet engines, can benefit from the incorporation of optical ignition systems to reduce the time for combustion and achieve higher combustion efficiency. For certain applications, a total combustion time can be specified as the time duration to burn x % of an initial mass of a fuel injected into a combustion chamber, as measured from the completion of delivery of a pulse of optical energy, where x % can be specified as 90%, 95%, 98%, 99%, 99.5%, or 100%, and where the mass of the fuel can be measured by, for example, a pressure trace from an initial pressure (e.g., in the range of about 1 μm to about 4 μm) using a piezoelectric pressure transducer. In some embodiments, a total combustion time of a distributed, optical ignition system can be significantly shorter relative to the use of conventional, single-point ignition systems, and can be no greater than about 150 ms, such as no greater than about 120 ms, no greater than about 100 ms, no greater than about 80 ms, no greater than about 60 ms, no greater than about 40 ms, or no greater than about 20 ms, and down to about 10 ms, down to about 5 ms, down to about 1 ms, or less. Optical ignition systems can provide additional advantages, such as lower cost and tower input power than conventional spark igniters. In addition, the optical ignition systems can be readily installed in a variety of combustion chambers, and can provide distributed ignition of fuels without requiring extreme high pressure or temperature.
Attention turns to
In the illustrated embodiment, the engine 100 includes an optical ignition system, which includes an optical source 114 and a controller 116, which is connected to the optical source 114 and coordinates operation of the optical source 114 relative to the other components of the engine 100. The controller 116 can be implemented in hardware, software, or a combination of hardware and software. Upon injection of the fuel and the particles into the combustion chamber 104, the controller 116 activates the optical source 114, which irradiates the particles through an optical window 118 included in, or otherwise connected to, the housing 102 and, thereby, ignites the fuel in a distributed fashion. Resulting combustion products expand and push the piston 106 downwardly, and removal of the combustion products from the combustion chamber 104 allow upward movement of the piston 106 back to its initial position. Various aspects of the optical ignition system illustrated in
Attention next turns to
In the illustrated embodiment, the engine 200 includes an optical ignition system, which includes an optical source 216 and a controller 218, which is connected to the optical source 216 and coordinates operation of the optical source 216 relative to the other components of the engine 200. Upon injection of the fuel and the particles into the combustion chamber 206, the controller 218 activates the optical source 216, which irradiates the particles through an optical window 220 included in, or otherwise connected to, the housing 202 and, thereby, ignites the fuel in a distributed fashion. Resulting combustion products are expelled through the nozzle 208, thereby producing thrust. Various aspects of the engine 200 and the optical ignition system illustrated in
The following example describes specific aspects of some embodiments of this disclosure to illustrate and provide a description for those of ordinary skill in the art. The example should not be construed as limiting this disclosure, as the example merely provides specific methodology useful in understanding and practicing some embodiments of this disclosure.
Aluminum, due to its large volumetric energy density of about 83.8 kJ/cm3, is an important fuel for solid rocket propulsion, high temperature processing, and MEMS. For example, small amounts of Al are integrated into MEMS to generate heat, microthrusts, and gases for actuation and power supply. However, a reliable and optical ignition technique is desirable for practical utilization of Al fuel. Especially for MEMS applications, the small Al quantity and feature size impose a challenge for reliable ignition with common ignition methods requiring physical contact, such as hotwires, heaters, and piezoelectronic igniters. Optical ignition by flash, instead, is very attractive because it works without physical contact and can achieve distributed ignition at multiple locations, thereby increasing reliability of ignition and flexibility of design. Optical flashes can be used to ignite Al nanoparticles (NPs) and other nanostructures, including carbon nanotubes, silicon nanowires, and graphene oxide. In these cases, the flash heats up the nanostructures to temperatures beyond their ignition temperatures by the photothermal effect, leading to ignition. Compared to Al NPs, Al microparticles (MPs) can be more suitable for practical systems since they are cheaper, safer to handle, and contain much higher Al content due to the smaller fraction of dead volume and weight of an inert Al2O3 shell. Nevertheless, it can be difficult to ignite Al MPs by flash due to their low light absorption and high ignition temperature, and ignition typically occurs with a large flash energy (e.g., >1 J/cm2 from a xenon flash lamp).
This example investigates the effect of adding WO3 NPs on the flash ignition of Al MPs. It is observed that the minimum flash ignition energy of Al MPs is greatly reduced by adding WO3 NPs because WO3 NPs improve both oxygen supply and light absorption from the flash. The combustion of Al MPs also can occur faster with the addition of nanoscale metal oxides.
Mixtures of Al MPs and WO3 NPs are prepared by ultra-sonication using dimethylformamide (DMF) as a solvent. To study the efficacy of WO3 NP-assisted flash ignition on Al MPs of different sizes, two different sizes of Al MPs, namely about 2.3 μm (Atlantic Equipment Engineers) and about 0.9 μm (Sigma-Aldrich) are separately mixed with WO3 NPs. Al MPs and WO3 NPs (about 80 nm, SkySpring Nanomaterials) are each weighed to satisfy the targeted fuel/oxidizer equivalence ratio while keeping a total mass of about 0.530 g. The Al MP and WO3 NP mixture is added to about 10 ml of DMF and sonicated for about 15 min to ensure uniform mixing. After sonication, the mixture is gently dried on a hotplate at about 100° C. for about 6 h to remove the DMF. Finally, the dried mixture powder is passed through a 140 mesh (105 μm) sieve to break up large agglomerates. The Al-to-WO3 equivalence ratio (φ) and normalized equivalence ratio (φn) of the mixture are represented in the following equation:
where mAl and MWO3 refer to the mass of Al and WO3, respectively, and the subscript st refers to the stoichiometric condition for the reaction 2Al+WO3→Al2O3+W. Although the Al MPs are encapsulated by a native inert Al2O3 shell (about 2-5 nm), the active Al content is about 97.5% for the small (about 0.9 μm) and about 99.0% for the large (about 2.3 μm) Al MPs with a 5 nm shell. Here, it is assumed that the entire mass of the Al MPs is Al when calculating the equivalence ratios.
A schematic of a flash ignition experimental setup is shown in
The wavelength-dependent light absorption properties of various mixture samples are obtained with an integrating sphere using a xenon lamp coupled to a monochromator (Model QEX7, PV Measurements, Inc.). For the reflectance (R %) measurement, the samples are mounted at the backside of the integrating sphere, and the reflectance spectra are normalized to the reflection of a white-standard. The transmittance spectra (T %) are obtained by comparing the transmittance of test samples with a calibrated Si reference photodiode. Since the scattering component is not separately counted in the measurement, the absorption (A %) and scattering (S %) are calculated with the formula, (A+S)=100%−T %−R %.
Optical images in
WO3 NPs influence the flash ignition of Al MPs in at least two ways: (i) increasing light absorption and (ii) decreasing ignition temperature by supplying oxygen to Al. To quantify the effect of WO3 NPs, the minimum flash ignition energy (Emin) for the mixture of Al MPs and WO3 NPs is plotted as a function of normalized Al/WO3 equivalence ratio in both air (squares) and inert N2 (circles) in
The above Emin measurements show that WO3 NPs are more effective oxidizers than air for Al MPs. In addition, WO3 NPs can also enhance the light absorption of the mixture of Al MPs/WO3 NPs upon flash exposure, which can increase the temperature rise due to the photothermal effect.
By way of summary, this example presents a study of the effect of WO3 NP addition on the flash ignition of Al MPs of two different sizes by measurement of the minimum flash ignition energy, Emin. Emin is greatly reduced by the addition of WO3 NPs for Al MPs of both sizes. For the smaller Al MPs, the reduction of Emin mainly derives from the more effective oxygen supply by WO3 NPs than by air. For the larger Al MPs, the Emin reduction is due to the combined effects of effective oxygen supply and light absorption enhancement by WO3 NPs. These results extend the flash ignition of more expensive and lower energy density Al NPs to inexpensive and higher energy density Al MPs.
While the invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention as defined by the appended claims. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, method, operation or operations, to the objective, spirit and scope of the invention. All such modifications are intended to be within the scope of the claims appended hereto. In particular, while certain methods may have been described with reference to particular operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the invention. Accordingly, unless specifically indicated herein, the order and grouping of the operations is not a limitation of the invention.
Claims
1. A method of combustion, comprising:
- introducing microparticles and nanoparticles into a combustion chamber, wherein the microparticles and the nanoparticles are formed of different materials; and
- using an optical source, irradiating the microparticles and the nanoparticles within the combustion chamber to ignite the microparticles.
2. The method of claim 1, wherein the nanoparticles are formed of a metal oxide.
3. The method of claim 2, wherein the metal oxide is tungsten oxide.
4. The method of claim 2, wherein the microparticles are formed of a metal.
5. The method of claim 4, wherein the metal is aluminum.
6. The method of claim 4, wherein a molar ratio of the metal oxide to the metal is in the range of 1:10 to 1:1.
7. The method of claim 1, wherein irradiating the microparticles and the nanoparticles is carried out at an energy density up to 1 J/cm2.
8. The method of claim 7, wherein the microparticles have sizes in the range of 500 nm to 1 μm.
9. The method of claim 7, wherein the microparticles have sizes in the range of 1 μm to 10 μm.
10. A reaction device comprising:
- a housing defining an internal chamber;
- a reaction material disposed within the internal chamber and including microparticles and nanoparticles that are formed of different materials; and
- an optical ignition system connected to the housing and operable to irradiate the microparticles and the nanoparticles to ignite the reaction material.
11. The reaction device of claim 10, wherein the microparticles are formed of a metal, and the nanoparticles are formed of a metal oxide.
12. The reaction device of claim 11, wherein the metal is aluminum.
13. The reaction device of claim 11, wherein the metal oxide is tungsten oxide.
14. The reaction device of claim 11, wherein a molar ratio of the metal oxide to the metal is in the range of 1:10 to 1:1.
15. The reaction device of claim 11, wherein a molar ratio of the metal oxide to the metal is in the range of 1:5 to 1:1.
16. The reaction device of claim 11, wherein the optical ignition system is operable to irradiate the microparticles and the nanoparticles at an energy density up to 1 J/cm2.
17. The reaction device of claim 16, wherein the microparticles have sizes in the range of 500 nm to 1 μm.
18. The reaction device of claim 16, wherein the microparticles have sizes in the range of 1 μm to 10 μm.
Type: Application
Filed: Feb 14, 2014
Publication Date: Jan 8, 2015
Inventors: Xiaolin Zheng (Stanford, CA), Yuma Ohkura (Stanford, CA)
Application Number: 14/181,202
International Classification: F23Q 13/00 (20060101);