SOLVATED METAL FUEL COMBUSTION SYSTEM AND METHOD

Abstract

The combustion system includes a metal additive and a polar outer-sphere electron transferring solvent. The metal additive is solvated in the polar outer-sphere electron transferring solvent. The polar outer-sphere electron transferring solvent may include liquid ammonia, methylamine, and/or hexamethylphosphoramide. The metal additive may include an alkali metal and/or an alkaline earth metal. For instance, the metal additive may include lithium, sodium, aluminum, zirconium, titanium, yttrium, hafnium, and/or magnesium.

Claims

1. A combustion system, comprising: a metal additive; and an outer-sphere electron transferring solvent, wherein the metal additive is solvated in the outer-sphere electron transferring solvent.

2. The combustion system of claim 1, wherein the outer-sphere electron transferring solvent includes liquid anhydrous ammonia.

3. The combustion system of claim 1, wherein the outer-sphere electron transferring solvent includes at least one of methylamine and hexamethylphosphoramide.

4. The combustion system of claim 1, wherein the metal additive includes at least one of an alkali metal and an alkaline earth metal.

5. The combustion system of claim 4, wherein the metal additive includes at least one of aluminum, zirconium, titanium, yttrium, hafnium, and magnesium.

6. The combustion system of claim 4, wherein the metal additive includes lithium.

7. The combustion system of claim 4, wherein the metal additive includes sodium.

8. The combustion system of claim 1, further comprising a hypergolic propellant.

9. The combustion system of claim 8, wherein the hypergolic propellant includes white fuming nitric acid.

10. A propellant fuel comprising a combustion system of claim 1.

11. A method of manufacturing a combustion system, the method comprising the steps of: providing an outer-sphere electron transferring solvent; providing a metal additive; and dissolving the metal additive within the outer-sphere electron transferring solvent.

12. The method of claim 11, further comprising a step of providing a hypergolic propellant.

13. The method of claim 12, further comprising a step of igniting the dissolved metal additive within the outer-sphere electron transferring solvent.

14. The method of claim 11, wherein the step of dissolving the metal additive within the outer-sphere electron transferring solvent utilizes an electrolysis process.

15. The method of claim 11, wherein the step of dissolving the metal additive within the outer-sphere electron transferring solvent utilizes a dissolution process.

16. The method of claim 11, wherein the step of dissolving the metal additive within the outer-sphere electron transferring solvent utilizes a radiation chemistry process.

17. The method of claim 11, wherein the step of dissolving the metal additive within the outer-sphere electron transferring solvent includes a reaction having the formula:
M+mNH.sub.3.fwdarw.[M(NH.sub.3).sub.m].sup.+e.sup.

18. The method of claim 11, wherein the metal additive is a porous metal.

19. The method of claim 18, wherein the step of dissolving the metal additive within the outer-sphere electron transferring solvent includes passing the outer-sphere electron transferring solvent through the porous metal.

Description

DRAWINGS

[0036] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations and are not intended to limit the scope of the present disclosure.

[0037] FIG. 1 is a plot diagram illustrating the gravimetric and volumetric energy densities of various fuels compared to liquid ammonia and liquid hydrogen;

[0038] FIG. 2 is a plot diagram illustrating the volumetric and gravimetric densities of various fuels, further depicting liquid ammonia having one of the highest volumetric H.sub.2 densities, even higher than liquid hydrogen itself;

[0039] FIG. 3 is a bar graph illustrating influential reactions on ignition sensitivity, further depicting that introducing NO 2 to the flame readily proceeds to stifle the radical pool and increase ignition delay times;

[0040] FIG. 4 is a box diagram of a combustion system, further depicting the combustion system having a metal additive, an outer-sphere electron transferring solvent, and a hypergolic propellant, according to one embodiment of the present disclosure;

[0041] FIG. 5 is a line graph comparing the combustion system to hydrazine and neat ammonia, further depicting the specific impulse of the combustion system outperforming the hydrazine and neat ammonia at a high oxidizer-to-fuel mass flow ratio, according to one embodiment of the present disclosure;

[0042] FIG. 6 is a line graph comparing the combustion system, as shown in FIG. 2, to hydrazine and neat ammonia, further depicting the specific impulse of the combustion system outperforming the hydrazine and neat ammonia at a high oxidizer-to-fuel mass flow ratio, according to one embodiment of the present disclosure;

[0043] FIG. 7 is a line graph comparing the combustion system, to hydrazine and neat ammonia, further depicting the combustion system having higher flame temperatures than neat liquid ammonia, which indicates the combustion system has more radicals and faster reactions to overcome poor combustion characteristics of neat liquid ammonia, according to one embodiment of the present disclosure;

[0044] FIG. 8 is a graph depicting a specific impulse calculation a function of oxidizer-to-fuel ratio and weight percent of lithium as the metal additive, further depicting an optimal O/F ratio between 2 and 2.5 for all weight percent values, according to one embodiment of the present disclosure;

[0045] FIG. 9 is a graph depicting a specific impulse calculation a function of oxidizer-to-fuel ratio and weight percent of sodium as the metal additive, according to one embodiment of the present disclosure;

[0046] FIG. 10 is a graph depicting a specific impulse calculation a function of oxidizer-to-fuel ratio and weight percent of calcium as the metal additive, further depicting an optimal O/F ratio around 2.25 for low concentrations of the metal additive 102 and around 1.5 for high concentrations of the metal additive 102, according to one embodiment of the present disclosure;

[0047] FIG. 11 is a schematic diagram of a solvation process for the combustion system, further depicting a quasi-free electron of lithium dissolving into solution, according to one embodiment of the present disclosure; and

[0048] FIG. 12 is a flowchart of a method for manufacturing the combustion system, according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

[0049] The following description of technology is merely exemplary in nature of the subject matter, manufacture, and use of one or more inventions, and is not intended to limit the scope, application, or uses of any specific invention claimed in this application or in such other applications as may be filed claiming priority to this application, or patents issuing therefrom. Regarding methods disclosed, the order of the steps presented is exemplary in nature, and thus, the order of the steps can be different in various embodiments, including where certain steps can be simultaneously performed. A and an as used herein indicate at least one of the item is present; a plurality of such items may be present, when possible. Except where otherwise expressly indicated, all numerical quantities in this description are to be understood as modified by the word about and all geometric and spatial descriptors are to be understood as modified by the word substantially in describing the broadest scope of the technology. About when applied to numerical values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If, for some reason, the imprecision provided by about and/or substantially is not otherwise understood in the art with this ordinary meaning, then about and/or substantially as used herein indicates at least variations that may arise from ordinary methods of measuring or using such parameters.

[0050] Although the open-ended term comprising, as a synonym of non-restrictive terms such as including, containing, or having, is used herein to describe and claim embodiments of the present technology, embodiments may alternatively be described using more limiting terms such as consisting of or consisting essentially of. Thus, for any given embodiment reciting materials, components, or process steps, the present technology also specifically includes embodiments consisting of, or consisting essentially of, such materials, components, or process steps excluding additional materials, components or processes (for consisting of) and excluding additional materials, components or processes affecting the significant properties of the embodiment (for consisting essentially of), even though such additional materials, components or processes are not explicitly recited in this application. For example, recitation of a composition or process reciting elements A, B and C specifically envisions embodiments consisting of, and consisting essentially of, A, B and C, excluding an element D that may be recited in the art, even though element D is not explicitly described as being excluded herein.

[0051] As referred to herein, disclosures of ranges are, unless specified otherwise, inclusive of endpoints and include all distinct values and further divided ranges within the entire range. Thus, for example, a range of from A to B or from about A to about B is inclusive of A and of B. Disclosure of values and ranges of values for specific parameters (such as amounts, weight percentages, etc.) are not exclusive of other values and ranges of values useful herein. It is envisioned that two or more specific exemplified values for a given parameter may define endpoints for a range of values that may be claimed for the parameter. For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that Parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping, or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if Parameter X is exemplified herein to have values in the range of 1-10, or 2-9, or 3-8, it is also envisioned that Parameter X may have other ranges of values including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, 3-9, and so on.

[0052] When an element or layer is referred to as being on, engaged to, connected to, or coupled to another element or layer, it may be directly on, engaged, connected, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being directly on, directly engaged to, directly connected to or directly coupled to another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., between versus directly between, adjacent versus directly adjacent, etc.). As used herein, the term and/or includes any and all combinations of one or more of the associated listed items.

[0053] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer, or section. Terms such as first, second, and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the example embodiments.

[0054] Spatially relative terms, such as inner, outer, beneath, below, lower, above, upper, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the FIG. is turned over, elements described as below, or beneath other elements or features would then be oriented above the other elements or features. Thus, the example term below can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0055] As shown in FIG. 4, the combustion system 100 includes a metal additive 102 and a polar outer-sphere electron transferring solvent 104. The metal additive 102 is solvated in the polar outer-sphere electron transferring solvent 104. In a specific example, the metal additive 102 may be solvated in the polar outer-sphere electron transferring solvent 104 via simple dissolution or electrolysis. By dissolving the metal additive 102 within the polar outer-sphere electron transferring solvent 104, the metallic-bonding system of the metal additive 102 may be uniquely combined with the covalent bonding system of the polar outer-sphere electron transferring solvent 104. It should be appreciated that by dissolving the metal additive 102 within the polar outer-sphere electron transferring solvent 104, the dissolved metal additive 102 may have more surface area exposed for potential combustion. Without being bound to any particular theory, it is believed this combination may advantageously increase flame temperatures and militate against flame-out conditions. Desirably, the combustion system 100 may offer greater performance compared to known environmentally-friendly fuel sources while operating at a high oxidizer to fuel mass ratio. The polar outer-sphere electron transferring solvent 104 may include liquid anhydrous ammonia, methylamine, and/or hexamethylphosphoramide. The metal additive 102 may include an alkali metal and/or an alkaline earth metal. More specifically, the metal additive 102 may include lithium, sodium, aluminum, zirconium, titanium, yttrium, hafnium, and/or magnesium. A skilled artisan may select other suitable materials for the metal additives 102 and/or the polar outer-sphere electron transferring solvent 104, within the scope of the present disclosure.

[0056] In certain circumstances, the combustion system 100 may be provided with various ratios of the metal additive 102 and the polar outer-sphere electron transferring solvent 104. In a specific example, the combustion system 100 may include up to around twenty percent of the metal additive 102 by weight. For instance, where sodium is provided as the metal additive 102 and liquid anhydrous ammonia is provided as the polar outer-sphere electron transferring solvent 104, the combustion system 100 may include up to around twenty percent sodium by weight. In a more specific example, the combustion system 100 may include up to around ten percent of the metal additive 102 by weight. For instance, where lithium is provided as the metal additive 102 and liquid anhydrous ammonia is provided as the polar outer-sphere electron transferring solvent 104, the combustion system 100 may include up to around ten percent lithium by weight. One skilled in the art may select other suitable ratios for providing the metal additive 102 and the polar outer-sphere electron transferring solvent 104, within the scope of the present disclosure.

[0057] In certain circumstances, a solvated electron solution may be formed by dissolving the metal additive 102 within the polar outer-sphere electron transferring solvent 104. Solvated electrons are quasi-free electrons in solution and are the smallest possible anion. In the present disclosure, solvated electrons may be formed in solvents that exhibit outer-sphere electron transfer via radiation chemistry, electrolysis, and/or by simple dissolution of specific metals. A skilled artisan may select other suitable ways to provide the solvated electron, within the scope of the present disclosure.

[0058] The simplest representation of the solvated electron in liquid anhydrous ammonia (LAA) takes the general form:

M+mNH.sub.3.fwdarw.[M(NH.sub.3).sub.m].sup.+e.sup.

[0059] Where M is a soluble metal and e.sup. is a quasi-free electron dissolved into solution. Depending on the solvated metal, a stable number of ammonia molecules (denoted m) will coordinate with the metal cation to form a complex. Provided as a non-limiting example, in the case of lithium, four ammonia molecules coordinating with one lithium cation may give the most stable coordination. With continued reference to the non-limiting example, a simplification of the solvation process of lithium in liquid anhydrous ammonia is shown in FIG. 11.

[0060] In reality, the number of solvated states is quite complex, with each state having unique physical and chemical properties. Due to the reactive nature of many of these solvation states, the solution slowly reacts with itself to form a metal amide:

2[M(NH.sub.3).sub.m].sup.+e.sup..fwdarw.2MNH.sub.2+H.sub.2+(2m2)NH.sub.3

[0061] Despite this side reaction, solvated electron solutions can be stable for days, depending on the metal additive 102 and the polar outer-sphere electron transferring solvent 104.

[0062] In certain circumstances, the combustion system 100 may have enhanced specific impulse and oxidizer-to-fuel mass flow ratio. As shown in FIGS. 5-6, the compulsion system outperformed hydrazine at higher oxidizer-to-fuel mass flow ratios. With reference to FIG. 7, the compulsion system had higher flame temperatures than neat NH.sub.3. Advantageously, it should be appreciated that more radicals and faster reactions may be obtained with the combustion system 100 to overcome the poor combustion characteristics of neat NH.sub.3. As shown in FIGS. 8-10, specific impulse calculations are provided for various metal additives 102. FIGS. 8-10 are both a function of oxidizer-to-fuel ratio and weight percent metal additive 102. Estimated ranges depend on the metal additive 102. For example, as shown in FIG. 8, lithium has an optimal O/F ratio between 2 and 2.5 for all weight percent values. As shown in FIG. 10, calcium has an optimal 0/F ratio around 2.25 for low concentrations of the metal additive 102 and around 1.5 for high concentrations of the metal additive 102.

[0063] In certain circumstances, as shown in FIG. 4, the combustion system 100 may include a hypergolic propellant 106. In a specific example, the hypergolic propellant 106 may include white fuming nitric acid. In a more specific example, the combustion system 100 coupled with a hypergolic propellant 106 may be provided as a propellant fuel. In a more specific example, the combustion system 100 coupled with a hypergolic propellant 106 may be provided as a non-carbonaceous propellant fuel. Additionally, the combustion system 100 coupled with a hypergolic propellant 106 may be provided as a propellant fuel that is less toxic than hydrazine. One skilled in the art may select other suitable uses for the combustion system 100, within the scope of the present disclosure.

[0064] Various ways of manufacturing the combustion system 100 are provided. For instance, as shown in FIG. 12, a method 200 may include a step 202 of providing a polar outer-sphere electron transferring solvent 104. The method 200 may include a step 204 of also providing a metal additive 102. The metal additive 102 may be dissolved within the polar outer-sphere electron transferring solvent 104. In a specific example, a hypergolic propellant may be provided. In a more specific example, the metal additive 102 dissolved in within the polar outer-sphere electron transferring solvent 104 may be ignited. One skilled in the art may select other suitable ways of manufacturing the combustion system 100, within the scope of the present disclosure.

[0065] In certain circumstances, the method 200 may include a way to provide the combustion system 100 on demand. For instance, the metal additive 102 may be specifically provided as a porous metal. In a specific example, the porous metal may have a pore size large enough to allow NH.sub.3 to flow therethrough. The step 206 of dissolving the metal additive 102 within the polar outer-sphere electron transferring solvent 104 may more particularly include selectively passing the polar outer-sphere electron transferring solvent 104 through the porous metal. It is also contemplated to provide the metal additive 102 as a powder bed or tubes to provide the same or similar function as the porous metal. A skilled artisan may select other suitable ways of manufacturing the on-demand combustion system 100, within the scope of the present disclosure.

[0066] Advantageously, the combustion system 100 may provide a more efficient and energy dense fuel source that maintains combustion by providing temporary oxidation protection of the metal additive 102, militates against flame-out conditions, and is less toxic than known combustion materials such as hydrazine. Desirably, the combustion system 100 may also militate against global pollution. For instance, in a specific example, the combustion system 100 may produce zero-carbon emissions.

[0067] Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Equivalent changes, modifications and variations of some embodiments, materials, compositions, and methods can be made within the scope of the present technology, with substantially similar results.