WO2014205029A1 - Gas generator and reactant that include nitroalcohol - Google Patents

Abstract

A gas generator includes a reactor and a reactant. The reactant includes nitroalcohol, and the reactor is operable to decompose the reactant to generate a gaseous product. Also disclosed is a reactant system for generating a gaseous product. The reactant system includes at least first and second reactants, one of which includes nitroalcohol. The first and second reactants are cooperatively thermally decomposable to generate the gaseous product. A method of providing a reactant system for generating a gaseous product includes contacting a first reactant with a second reactant, and the first reactant includes nitroalcohol.

Description

GAS GENERATOR AND REACTANT THAT

INCLUDE NITROALCOHOL

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present disclosure claims priority to United States Provisional Patent Application No. 61/836,638, filed June 18, 2013 and United States Provisional Patent Application No. 61/859,146, filed July 26, 2013.

BACKGROUND

[0002] Hydrazine compounds, such as hydrazine, monomethylhydrazine, and dimethylhydrazine, have been used fuel, propellant, or monopropellant. For example, as a monopropellant, hydrazine compounds decompose into gas in the presence of a specialized catalyst. The generated gas can be used as a working fluid or to produce thrust. Non- hydrazine-based monopropellants are also used and can include propylene glycol dinatrate, dibutyl sebacate, and 2-nitrodiphenylamine.

SUMMARY

[0003] A gas generator according to an example of the present disclosure includes a reactor, and a reactant that includes nitroalcohol. The reactor is operable to decompose the reactant to generate a gaseous product.

[0004] In a further embodiment of any of the foregoing embodiments, the nitroalcohol includes a nitrogen dioxide moiety.

[0005] In a further embodiment of any of the foregoing embodiments, the nitrogen dioxide moiety is bonded to a carbon chain that includes a hydroxyl moiety.

[0006] In a further embodiment of any of the foregoing embodiments, the carbon chain includes at least two carbon atoms.

[0007] In a further embodiment of any of the foregoing embodiments, the carbon chain includes two carbon atoms.

[0008] In a further embodiment of any of the foregoing embodiments, the nitroalcohol is HOCH₂CH₂N0₂.

[0009] In a further embodiment of any of the foregoing embodiments, the reactant includes an additive selected from the group consisting of ammonia, ammonium, dinitramide, ammonium hydroxide, ammonium nitrate, hydrogen peroxide, hydroxylamine, hydroxylammonium nitrate, nitric acid, water, and combinations thereof. [0010] In a further embodiment of any of the foregoing embodiments, the reactant consists of the nitroalcohol and an additive selected from the group consisting of ammonia, ammonium, dinitramide, ammonium hydroxide, ammonium nitrate, hydrogen peroxide, hydroxylamine, hydroxylammonium nitrate, nitric acid, water, and combinations thereof.

[0011] In a further embodiment of any of the foregoing embodiments, the reactant includes hydrazine.

[0012] In a further embodiment of any of the foregoing embodiments, the reactant includes nitric acid and water.

[0013] In a further embodiment of any of the foregoing embodiments, the reactant consists of the nitroalcohol.

[0014] In a further embodiment of any of the foregoing embodiments, the reactant consists of the nitroalcohol and hydrazine.

[0015] In a further embodiment of any of the foregoing embodiments, the reactant consists of the nitroalcohol, hydrazine, nitric acid, and water.

[0016] In a further embodiment of any of the foregoing embodiments, the reactor includes an injector operable to inject the reactant into the reactor, and an outlet expelling the gaseous product.

[0017] In a further embodiment of any of the foregoing embodiments, the reactor includes a heating element.

[0018] In a further embodiment of any of the foregoing embodiments, the reactor includes a catalyst.

[0019] In a further embodiment of any of the foregoing embodiments, the catalyst includes iridium metal.

[0020] In a further embodiment of any of the foregoing embodiments, the outlet includes a convergent-divergent nozzle.

[0021] In a further embodiment of any of the foregoing embodiments, the reactor includes a first injector operable to inject the reactant into the reactor, a second injector operable to inject another reactant into the reactor, and an outlet expelling the gaseous product.

[0022] In a further embodiment of any of the foregoing embodiments, the reactor includes a solid phase co-reactant.

[0023] In a further embodiment of any of the foregoing embodiments, the solid phase co-reactant includes iodine pentoxide. [0024] In a further embodiment of any of the foregoing embodiments, the solid phase co-reactant includes iodic acid.

[0025] A reactant system for generating a gaseous product according to an example of the present disclosure includes at least first and second reactants, one of which includes nitroalcohol. The first and second reactants are cooperatively thermally decomposable to generate a gaseous product.

[0026] In a further embodiment of any of the foregoing embodiments, the first reactant includes the nitroalcohol and the second reactant includes a reactant that has a higher vapor pressure than the nitroalcohol.

[0027] In a further embodiment of any of the foregoing embodiments, the reactant with the higher vapor pressure is hydrazine.

[0028] In a further embodiment of any of the foregoing embodiments, the first reactant includes the nitroalcohol and the second reactant includes a solid phase reactant.

[0029] A method of providing a reactant system for generating a gaseous product according to an example of the present disclosure includes contacting a first reactant with a second reactant, wherein the first reactant includes nitroalcohol.

[0030] In a further embodiment of any of the foregoing embodiments, the second reactant has a higher vapor pressure than the nitroalcohol.

[0031] In a further embodiment of any of the foregoing embodiments, the second reactant includes hydrazine.

[0032] In a further embodiment of any of the foregoing embodiments, the second reactant includes a solid phase reactant.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.

[0034] Figure 1 illustrates a sectional view from the side of a gas generator where the reaction is initiated by a granular catalyst.

[0035] Figure 2 illustrates a sectional view from the side of a gas generator where the reaction is initiated by preheating of a reactor.

[0036] Figure 3 illustrates a sectional view from the side of gas generator made where the reaction is initiated by a heating element. [0037] Figure 4 illustrates a sectional view from the side of a gas generator where the reaction is initiated by contact with a co-reactant initially placed within a reactor.

[0038] Figure 5 illustrates a sectional view from the side of a gas generator where an additional reactant is injected.

[0039] Figure 6 illustrates a sectional view from the side of a gas generator that includes a convergent-divergent nozzle.

[0040] Figure 7 illustrates a graph comparing differential scanning calorimetry data for a reactant disclosed herein and neat hydrazine.

DETAILED DESCRIPTION

[0041] Figure 1 schematically illustrates an example gas generator 20. As will be appreciated from the description herein, the gas generator 20 is operable to generate a gaseous product from a reactant or reactant system that includes nitroalcohol. The examples herein can be used in, but are not limited to, thrusters, pressurization systems, and power generation systems. Further, vapor-toxicity risk can be reduced or eliminated by using the nitroalcohol compared to use hydrazine compounds or other monopropellants.

[0042] In the example illustrated in Figure 1, the gas generator 20 includes a reactor 22 that contains a porous catalyst 24. For example, the porous catalyst 24 is a granular catalyst that includes iridium active metal. A reactant 26 that includes nitroalcohol can be introduced through an injector 28 into the reactor 22.

[0043] Upon contact with the catalyst 24, the reactant 26 decomposes to form gaseous products. In this example, the gaseous products are discharged through a porous plate 30 within or affixed to the reactor 22, which serves to retain the catalyst 24. The gaseous products are expelled through an outlet 32 of the reactor 22. It is to be appreciated that the outlet 32 is exemplary, and any means of communication of the gaseous products to a nozzle, pressurized system, motor, or other device by which the gas is to be used, including direct incorporation therein, may be alternatively employed.

[0044] Prior to the start of flow of the reactant 26 into the reactor 22, the catalyst Error! Bookmark not defined, and/or reactor 22 can be preheated by arbitrary means to initiate reaction of the reactant 26, after which heat transfer from the reaction can be employed to maintain the catalyst 24 and/or reactor 22 at elevated temperature sufficient to sustain the reaction of continuing reactant inflow.

[0045] The reactant 26 includes nitroalcohol. For example, the nitroalcohol includes one or more nitrogen dioxide moieties (-N0₂). The nitrogen dioxide moiety can be bonded to a carbon chain that is also bonded to one or more hydroxyl moieties (-OH). In one example, the carbon chain includes at least two carbon atoms, and in the further example, the carbon chain includes only two carbon atoms. With only two carbon atoms, the nitroalcohol is HOCH₂CH₂NO₂ (nitroethanol).

[0046] The reactant 26 can include only the nitroalcohol or the nitroalcohol with one or more additives. For example, the additives can include ammonia, ammonium, dinitramide, ammonium hydroxide, ammonium nitrate, hydrogen peroxide, hydroxylamine, hydroxylammonium nitrate, nitric acid, water, or combinations thereof. In further examples, the reactant 26 has only the nitroalcohol and the additive or additives.

[0047] In addition to the nitroalcohol, the reactant 26 can also include other constituent reactants, such as reactants that have a higher vapor pressure than the nitroalcohol. One example additional constituent reactant is hydrazine, which has higher vapor pressure than the nitroalcohol. The additional constituent reactant or reactants can be mixed in the reactant 26 with the nitroalcohol or injected separately into the reactor 26. In a further example, the reactant 26 includes only the nitroalcohol and the hydrazine. In further examples, in addition to the nitroalcohol and the hydrazine, the reactant 26 also includes nitric acid and water. In another example the reactant 26 includes only the nitroalcohol, hydrazine, nitric acid, and water.

[0048] Nitroalcohols are relatively effective polar solvents and may be readily combined with other constituents, as discussed above, to formulate variations of the reactant 26 to enhance reactivity, reduce ignition temperature, increase performance, or tailor other properties of interest in the particular implementation. In particular, nitroalcohol may form strong hydrogen bonds with other solutes such that a low vapor-toxicity composite mixture can be formed by mixing nitroalcohol with one or more higher vapor pressure additives or reactants. The nitroalcohol thus can serve to suppress vapor pressure of a solute by interaction with the low-vapor-pressure nitroalcohol solvent. Nitroalcohols are also effective solvents for apolar solutes, for example nitroesters, such that the reactant 26 can include constituents that ordinarily would not be mutually soluble.

[0049] Figure 2 illustrates another example gas generator 120. In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of one-hundred or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding elements. In this example, the gas generator 120 omits the catalyst 24 and retaining plate 30 and the reactor 22 is preheated by arbitrary means such that reaction of incoming reactant 26 is initially thermally induced by contact with the heated surfaces of the reactor 22, and thereafter sustained by interaction of later inflowing reactant 26 with already-produced reaction products and/or by further contact with heated surfaces of the reactor 22 (by heat transfer from the reaction products).

[0050] Figure 3 illustrates another example gas generator 220. In this example, the gas generator 220 includes a heating element 240 within the reactor 22. The heating element 240 serves to facilitate inducing the decomposition reaction of the reactant 26. In one example, the heating element 240 is, but is not limited to, an electro-resistive heating element. The heating element 240 can be activated as long as reactant 26 is introduced through the injector 28. The heating element 240 may alternatively be deactivated upon initiation of the reaction, whereby reaction of continuing reactant inflow is thereafter sustained by interaction with already-produced reaction products and/or by contact with heated surfaces of the reactor 22 or heating element 240.

[0051] Figure 4 illustrates another example gas generator 320. In this example, the reactor 22 includes a co-reactant. The co-reactant 342 spontaneously reacts with the reactant 26 upon contact. For example, the co-reactant 342 is a solid phase reactant and can include iodine pentoxide (I₂O₅) or iodic acid (HIO₃). The co-reactant 342 can initially be contained within the reactor 22. After depletion of the co-reactant 342, reaction of continuing reactant 26 inflow may be sustained by interaction with already-produced reaction products and/or by contact with heated surfaces of the reactor 22.

[0052] Figure 5 illustrates another example gas generator 420. In this example, the reactor 22 includes a second injector 428 through which a second reactant 426 can be injected. For example, the second reactant 426 is different in composition constituents from the reactant 26 and is spontaneously reactive with the reactant 26 injected through the injector 28, thereby initially inducing reaction of the reactants 26 and 426. Flow of the second reactant 426 through the injector 428 can be either sustained or discontinued following initiation of the reaction, whereby continuing reaction of incoming reactant 26 is sustained by interaction with already-produced reaction products and/or by contact with heated surfaces of the reactor 22.

[0053] It is to be further appreciated that the reactant 26 can itself constitute a reactant system of several reactants as described herein, a reactant system that includes the reactants 26 and 426, a reactant system that includes the reactant 26 and co-reactant 342, or a reactant system that includes the reactants 26 and 426 and co-reactant 342. Thus, the reactant system can include a mix of reactants (constituents), one of which includes nitroalcohol, that is then injected into the reactor for decomposition to generate the gaseous products. Additionally, the reactant system can include one or more reactants (constituents), one of which is nitroalcohol, in combination with the solid co-reactant 342, which are relatively briefly in contact prior to initiation of the decomposition reaction. The reactant constituents of such reactant systems are cooperatively thermally decomposable, to generate the gaseous products, in that there is a dependence among the reactant constituents to initiate or sustain the decomposition reaction.

[0054] Figure 6 illustrates another example gas generator 520, which is a variation of the gas generator 20 of Figure 1. In this example, the gas generator 520 is employed for thrust and includes a convergent-divergent nozzle 544. The nozzle 544 includes a convergent section 544a that funnels into a narrow throat 544. The narrow throat 544b then expands to a divergent section 544c. One example of the convergent-divergent nozzle 544 is a de Laval nozzle. Additionally, it is also to be understood that the features of the gas generators described herein can be combined such that further embodiments include features from any or all of the illustrated examples.

[0055] In comparison to known monopropellants, such as neat hydrazine, nitroalcohol has lower toxicity and lower vapor pressure, which facilitates handling conditions. Nitroalcohol also has high utility in a wide range of temperatures over which the nitroalcohol remains flowable in its liquid phase, which also facilitates use over a wider operating temperature range. Additionally, nitroalcohol has relatively high density, which facilitates compact storage. In decomposing to relatively low-molecular-weight product species, nitroalcohol also yields relatively high specific impulse when exhausted through a nozzle, and produces a relatively large volume of gas per unit mass of reactant, yielding higher specific performance at relatively low reaction temperatures comparable to known alternatives to hydrazine. Thus, the use of high-cost refractory alloys that may be required for propellants that react at higher temperatures may be avoided or reduced.

[0056] In one example, pure nitroethanol has an ambient temperature vapor pressure of 2 Pa. Neat hydrazine has a ambient temperature vapor pressure of 1900 Pa. Nitroethanol also has an ambient pressure liquidus phase regime ranging from -80 °C (freezing point) to 194 °C (boiling point), whereas neat hydrazine has a liquidus phase regime ranging from only 2 °C to 114 °C. At 25 °C nitroethanol has a storage density of 1.27 g/mL, compared to 1.0 g/mL for neat hydrazine. While producing slightly lower specific impulse than neat hydrazine, the density-specific impulse (the product of storage density and specific impulse) of nitroethanol, is 17% higher at a product gas temperature of only 925 °C. [0057] The following additional examples are illustrative and not to be taken as limiting the scope of the disclosure.

[0058] Rapid thermal decomposition of nitroethanol was demonstrated on a plate heated to 190 °C. In a comparative test, nitroethanol was exposed to a catalyst comprising iridium active metal and demonstrated substantial acceleration of the reaction at 167 °C. In another comparative test, ten mass percent hydrazine addition to nitroethanol was demonstrated to promote increased reactivity of the mixture at 100 °C.

[0059] Figure 7 illustrates differential scanning calorimetry (DSC) analysis of hydrazine and nitroethanol. Dashed line 650 represents a trace for neat hydrazine and solid line 652 represents a trace of a mixture of 90% by weight nitroethanol and 10% by weight of hydrazine. As shown, the neat hydrazine has a positive heat- flow peak and the mixture has no such peak. Thermal decomposition of the mixture initiates between 150 °C and 160 °C, indicating an increase in the boiling point of the hydrazine component of the mixture of at least approximately 50°C. Another mixture of 70% by weight nitroethanol and 30% by weight hydrazine (i.e., approximately a one-to-one molar mixture) demonstrated similar results. Smaller boiling point increases of approximately 40 °C and 30 °C were observed for, respectively, 50% and 75% of hydrazine.

[0060] Mixtures of nitroethanol/hydrazine of 90/10, 70/30, 50/50, and 25/75 demonstrated moderate reactivity when exposed to catalyst comprising iridium active metal at ambient temperature (approximately 20°C). An additional mixture comprising equal parts by mole of nitroethanol and hydrazine with the addition of ten mole percent concentrated nitric acid (containing thirty mass % water) also demonstrated substantially increased reactivity when exposed to the same catalyst at ambient temperature. It is to be appreciated that the method of combining nitroalcohol with a hydrazine compound in order to produce a reduced vapor pressure mixture may be employed in a wide range of applications without altering the examples dislcosed herein.

[0061] The present disclosure may be used to provide a reduced vapor toxicity alternative for hydrazine and other monopropellants. The present disclosure can be used to provide a method of reducing the vapor pressure of reactants and propellants comprising hydrazine compounds, thereby reducing or eliminating the costs of special handling precautions and equipment known for hydrazine. The present disclosure can also be used for maintaining substantially lower gas product temperatures, yielding more volumetrically- efficient gas production and utilization, providing higher storage density and/or total system volumetric efficiency, reducing vapor-toxicity, reducing the spontaneous reactivity of a propellant with other materials likely to be present in the working environment, generating thrust with higher specific impulse, generating thrust with similar or better specific impulse while maintaining substantially lower gas product temperatures, generating thrust with higher storage density and/or total system volumetric efficiency, generating pressure with reduced vapor-toxicity, generating pressure while reducing spontaneous reactivity of the propellant with other materials likely to be present in the working environment, generating pressure yielding more volumetrically-efficient gas production, generating pressure with volumetrically-efficient gas production and usage while maintaining substantially lower gas product temperatures, generating pressure with higher storage density and/or total system volumetric efficiency, generating power with reduced vapor-toxicity, generating power with reduced spontaneous reactivity of the propellant with other materials likely to be present in the working environment, generating power with more volumetrically-efficient gas production, generating power with more volumetrically-efficient gas production and usage while maintaining substantially lower gas product temperatures, or generating power with higher storage density and/or total system volumetric efficiency.

[0062] Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.

[0063] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.

Claims

CLAIMS What is claimed is:

1. A gas generator comprising:

a reactor; and

a reactant including nitroalcohol, the reactor operable to decompose the reactant to generate a gaseous product.

2. The gas generator as recited in claim 1, wherein the nitroalcohol includes a nitrogen dioxide moiety.

3. The gas generator as recited in claim 2, wherein the nitrogen dioxide moiety is bonded to a carbon chain that includes a hydroxyl moiety.

4. The gas generator as recited in claim 3, wherein the carbon chain includes at least two carbon atoms.

5. The gas generator as recited in claim 3, wherein the carbon chain includes two carbon atoms.

6. The gas generator as recited in claim 1 , wherein the nitroalcohol is HOCH₂CH₂N0₂.

7. The gas generator as recited in claim 1, wherein the reactant includes an additive selected from the group consisting of ammonia, ammonium, dinitramide, ammonium hydroxide, ammonium nitrate, hydrogen peroxide, hydroxylamine, hydroxylammonium nitrate, nitric acid, water, and combinations thereof.

8. The gas generator as recited in claim 1, wherein the reactant consists of the nitroalcohol and an additive selected from the group consisting of ammonia, ammonium, dinitramide, ammonium hydroxide, ammonium nitrate, hydrogen peroxide, hydroxylamine, hydroxylammonium nitrate, nitric acid, water, and combinations thereof.

9. The gas generator as recited in claim 1, wherein the reactant includes hydrazine.

10. The gas generator as recited in claim 9, wherein the reactant includes nitric acid and water.

11. The gas generator as recited in claim 1, wherein the reactant consists of the nitroalcohol.

12. The gas generator as recited in claim 1, wherein the reactant consists of the nitroalcohol and hydrazine.

13. The gas generator as recited in claim 1, wherein the reactant consists of the nitroalcohol, hydrazine, nitric acid, and water.

14. The gas generator as recited in claim 1, wherein the reactor includes an injector operable to inject the reactant into the reactor, and an outlet expelling the gaseous product.

15. The gas generator as recited in claim 14, wherein the reactor includes a heating element.

16. The gas generator as recited in claim 14, wherein the reactor includes a catalyst.

17. The gas generator as recited in claim 16, wherein the catalyst includes iridium metal.

18. The gas generator as recited in claim 14, wherein the outlet includes a convergent- divergent nozzle.

19. The gas generator as recited in claim 1, wherein the reactor includes a first injector operable to inject the reactant into the reactor, a second injector operable to inject another reactant into the reactor, and an outlet expelling the gaseous product.

20. The gas generator as recited in claim 1 , wherein the reactor includes a solid phase co- reactant.

21. The gas generator as recited in claim 20, wherein the solid phase co-reactant includes iodine pentoxide.

22. The gas generator as recited in claim 20, wherein the solid phase co-reactant includes iodic acid.

23. A reactant system for generating a gaseous product, the reactant system comprising: at least first and second reactants, one of which includes nitroalcohol, the at least first and second reactants being cooperatively thermally decomposable to generate a gaseous product.

24. The reactant system as recited in claim 23, wherein the first reactant includes the nitroalcohol and the second reactant includes a reactant that has a higher vapor pressure than the nitroalcohol.

25. The method as recited in claim 24, wherein the reactant with the higher vapor pressure is hydrazine.

26. The method as recited in claim 24, wherein the first reactant includes the nitroalcohol and the second reactant includes a solid phase reactant.

27. A method of providing a reactant system for generating a gaseous product, the method comprising:

contacting a first reactant with a second reactant, wherein the first reactant includes nitroalcohol.

28. The method as recited in claim 27, wherein the second reactant has a higher vapor pressure than the nitroalcohol.

29. The method as recited in claim 28, wherein the second reactant includes hydrazine.

30. The method as recited in claim 27, wherein the second reactant includes a solid phase reactant.