Liquid propellant

Details Liquid propellant Liquid propellant

1999-02-26

2001-07-03

Carone, Michael J. (Department: 3641)

Explosive and thermic compositions or charges

Containing liquefied gaseous fuel or liquefied oxygen...

C149S045000

Reexamination Certificate

active

06254705

ABSTRACT:

The present invention relates to liquid propellants for the purpose of generating hot gases, or for the generating of energy-rich gases on combustion thereof, which gases can be used in a secondary reaction. These gases are suitable for driving a turbine, vane or piston motor, inflating air bags or for rocket propulsion, or other vessel or vehicle propulsion. More particularly the present invention relates to such propellants especially suited for space applications.
BACKGROUND OF THE INVENTION
A high performing, low risk and low cost monopropellant is the most attractive concept for chemical propulsion. A monopropellant will require a minimum of components to build up a propulsion system and thus will lead to minimum complexity and minimum cost.
The dominating monopropellant for spacecraft propulsion is hydrazine. The major advantages of hydrazine systems are long flight heritage and well-established technology. The major drawbacks of hydrazine systems are the hazards involved. Hydrazine is highly toxic and carcinogenic and hence, rigorous routines are required for manufacturing, handling and operation of hydrazine systems.
Due to hazards, and therefore the total cost, an alternative propellant is highly attractive. Thus, hydrazine will sooner or later be replaced due to cost reduction, safer handling and new requirements on personal safety and environmental requirements. However, this requires that the alternative propellant reach maturity and has been flight qualified.
As indicated above, hydrazine is today widely used as a monopropellant for space applications, but unfortunately it is very toxic, making it hard and expensive to handle. Thus new, less toxic monopropellants are desired.
Ammonium dinitramide (ADN) is a new solid oxidizer, mainly intended for high performance composite rocket propellants. ADN and other similar compounds are the subject of several patents for application as solid composite rocket propellants and as explosives, both for pyrotechnic applications in general and for other uses, such as in inflators for air-bags. The composite explosives of this type typically comprise ADN (or some other compound) as an oxidizer, an energetic binder (e.g. energetically substituted polymers), a reactive metal and other typical propellant ingredients such as curatives and stabilizers. One of the disadvantages of ADN, as a solid oxidizer, is its high hygroscopicity.
SUMMARY OF THE INVENTION
Thus, the existing liquid monopropellants are subject to a number of disadvantages, such as health hazards for personnel handling the propellants, environmental hazards in general due to the toxic nature thereof. A further disadvantage of these liquid monopropellants are the costs associated with the additional safety arrangements required for handling and usage of these monopropellants. Therefore it is an object of the present invention to provide a novel liquid propellant that is low-hazardous both from a handling point of view and from an environmental one, that does not develop smoke and which is liquid. In summary the propellant should exhibit the following properties:
low toxicity
no toxic or combustible vapours
higher theoretical specific impulse (as compared to hydrazine)
higher density (as compared to hydrazine)
easily ignitable
storable at a temperature between +10° C. and +50° C.
low sensitivity.
The above stated object is achieved according to the present invention with a liquid propellant as defined in claim
1
, comprising a solution of an oxidizer of the general formula
X-D  (I)
wherein X is a cation; and D is the anion dinitramide (
−
N(NO
2
)
2
), and a fuel. The cation can be selected from the group consisting of metals, organic ions and inorganic ions.
Examples of suitable cations are OHNH
3
+
, NH
4
+
, CH
3
NH
3
+
, (CH
3
)
2
NH
2
+
, (CH
3
)
3
NH
+
, (CH
3
)
4
N
+
, C
2
H
5
NH
4
+
, (C
2
H
5
)
2
NH
2
+
, C
2
H
5
)
3
NH
+
, (C
2
H
5
)
4
N
+
, (C
2
H
5
)(CH
3
)NH
2
+
, (C
2
H
5
)(CH
3
)NH
2
+
, (C
2
H
5
)(CH
3
)
2
N
+
, (C
3
H
7
)
4
N
+
, (C
4
H
9
)
4
N
+
, N
2
H
5
+
, CH
3
N
2
H
4
+
, (CH
3
)
2
N
2
H
3
+
, (CH
3
)
3
N
2
H
2
+
, (CH
3
)
4
N
2
H
+
, (CH
3
)
5
N
2
+
.
The preferred cations are ammonium and hydroxylammomum ions.
Metal ions can be used, but will generally lead to the generation of smoke which is often undesirable. Examples of groups of metals which can be used are the alkali metals, and the alkaline earth metals, especially the former, specific examples being lithium, sodium, and potassium ions.
The propellant comprises a fuel which can be selected from the group consisting of mono-, di-, tri- and poly-hydric alcohols, aldehydes, ketones, amino acids, carboxylic acids, primary, secondary and tertiary amines, and mixtures thereof, or any other compound which can react with the dinitramide oxidizer, and in which said oxidizer is soluble, and/or which is soluble in a suitable solvent, such as water, wherein the oxidizer is soluble, thereby forming a liquid monopropellant exhibiting the above-mentioned desirable characteristics.
Thus, when ADN is used as the oxidizer in the propellants of the present invention, the high hygroscopicity of ADN is a major advantage, especially when said propellants contain water.
Examples of compounds usable as the fuel are polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, tetramethylene glycol, ethylene glycol monoethyl ether, propylene glycol, dipropylene glycol, dimethoxytetraethylene glycol, diethylene glycol monomethyl ether, the acetate of ethylene glycol monoethyl ether and the acetate of diethylene glycol monoethyl ether; ketones, such as for example, acetone and methyl butyl ketone; monohydric alcohols such as methanol, propanol, butanol, phenol and benzyl alcohol; ethers, such as dimethyl and diethyl ether, and dioxane; also, the nitrites such as acetonitrile; the sulfoxides such as dimethylsulfoxides; sulfones such as tetrahydrothiophene-1,1-dioxide; the amines such as ethylamine, diethylamine, ethanolamine, hydroxylamine; substituted hydroxylamines such as methyl and ethyl hydroxylamine; and mixtures thereof.


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Kazakov et al., “Kinetics of the termal decomposition of Dinitramide 2.* Kinetics of the reaction of dinitramide with decomposition products and other components of a solution”,Russian Chemical Bulletinvol. 47, No. 1, pp. 39-45, (1998).

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