Fuel and related compositions – Solidified liquid
Reexamination Certificate
2000-07-18
2001-10-09
Medley, Margaret (Department: 1714)
Fuel and related compositions
Solidified liquid
C044S327000, C149S001000, C149S017000, C149S045000, C149S074000, C149S115000, C149S060000, C149S115000
Reexamination Certificate
active
06299654
ABSTRACT:
BACKGROUND OF THE INVENTION
A liquid or gel monopropellant thruster consists of a pressurization system, propellant tank, fuel valve, and a catalytic bed reactor with a nozzle. The thruster begins operation when the pressurization system has been activated and the monopropellant is pressurized in the propellant tank. When the fuel valve opens, the pressurized monopropellant is expelled into the catalytic bed reactor where the monopropellant is exothermically decomposed into small molecular weight gasses. Hydrazine and hydrazine blends have been considered as monopropellants because of their ability to decompose at ambient conditions on an iridium catalyst to form warm (1000° F. to 1500° F.) gases. Hydrazine is undesirable because of its toxicity and high freezing point (34° F.).
SUMMARY OF THE INVENTION
The subjects of this patent are three amine azide monopropellants, dimethylaminoethylazide (DMAZ), pyrollidinylethylazide (PYAZ) and diethylaminoethylazide (DEAZ). Amine azides decompose on an iridium catalyst at 400° F. and have very low freezing points (<−65° F.). Dimethylaminoethylazide (DMAZ) has been tested and is a suitable replacement for hydrazine in monopropellant thruster applications.
Heat of formation and density data has been collected for all three compounds and DMAZ has been tested in a catalytic bed reactor. The amine azides DMAZ and PYAZ have already been shown to be good hypergolic fuels with inhibited red fuming nitric acid. These compounds are good candidates for monopropellants because the azide moiety present in each fuel decomposes exothermically to sustain the operation of the catalytic bed reactor.
Calorimetry methods have been used to determine the heats of formation of the compounds since this information has not been published in the open literature. The freezing points have been verified using differential scanning calorimetry (DSC) methods. The boiling points have been determined by observation.
REFERENCES:
patent: 4120151 (1978-10-01), Quigley
patent: 4620415 (1986-11-01), Schmidt
patent: 4741742 (1988-05-01), Miller et al.
patent: 5133183 (1992-07-01), Asaoka et al.
patent: 5152136 (1992-10-01), Chew et al.
patent: 5621156 (1997-04-01), Thompson
patent: 6013143 (2000-01-01), Thompson
patent: 6210504 (2001-04-01), Thompson
Bush Freddie M.
Medley Margaret
The United States of America as represented by the Secretary of
Tischer Arthur H.
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