Core-Shell Energetic Particle for Hypergolic Ignition
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Solution Overview
Problem
Hypergolic propellants using fuels like monomethylhydrazine and nitrogen tetroxide are toxic and carcinogenic, and their alternatives, such as hydrogen peroxide with kerosene, face issues with ignition delay and two-phase flow losses due to the propensity of catalytic/reactive additives to aggregate and form agglomerates, reducing rocket performance.
Innovation Solution
A particle comprising an energetic fuel additive and an ignition agent in a core-shell structure, where the ignition agent, such as a metal hydride, is deposited on the surface of the energetic fuel additive, increasing the catalytic surface area and reducing ignition delay by enhancing the reaction with hydrogen peroxide, thereby improving hypergolic ignition efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If catalytic/reactive additives are used to enable hypergolic ignition of hydrogen peroxide with kerosene, then ignition is achieved, but the additives aggregate and form agglomerates causing two-phase flow losses
Solution Approach 1:
The additive is segmented into discrete particles with controlled size distribution (1-100 micrometers). This segmentation prevents aggregation by maintaining particles as separate entities that can be properly suspended and distributed in the propellant mixture, eliminating the agglomeration problem while preserving catalytic activity for hypergolic ignition.
Solution Approach 2:
The patent applies different properties to different aspects of the additive system: using metal hydrides (NaBH4, LiBH4) with specific catalytic properties for ignition, while controlling particle size and distribution for optimal flow characteristics. The local quality principle is applied by optimizing the surface-area-to-mass ratio of individual particles to maximize catalytic efficiency while minimizing aggregation tendencies.
2Loss of time
If a large quantity of catalytic/reactive additives is used to reduce ignition delay time, then ignition delay is reduced, but two-phase flow losses increase
Solution Approach 1:
The patent changes the physical and chemical parameters of the additive system by selecting metal hydrides with high reactivity toward hydrogen peroxide. This parameter change (using highly reactive metal hydrides instead of conventional catalysts) reduces ignition delay time while allowing for lower additive concentrations, thereby minimizing two-phase flow losses.
Solution Approach 2:
The patent creates a composite system combining metal hydride particles with kerosene-based fuel and hydrogen peroxide oxidizer. This composite material approach allows the metal hydride surface to catalyze the decomposition of hydrogen peroxide, generating heat that ignites the kerosene fuel, achieving rapid ignition with minimal additive quantity.
3Use of energy by moving object
If energetic particles are used to improve rocket performance, then energy density increases, but particles aggregate and form agglomerates slowing gaseous product velocity
Solution Approach 1:
The energetic particles are segmented into fine size ranges (1-100 micrometers) to prevent aggregation. This segmentation ensures that particles remain dispersed and do not form agglomerates that would impede gas flow. The fine particle size also increases surface area for combustion reactions, maintaining high energy density while preserving gaseous product velocity.
Solution Approach 2:
The patent applies local quality by using metal hydride particles with specific surface properties that enhance catalytic activity while maintaining particle dispersion. The surface characteristics of the metal hydride particles are optimized to promote uniform distribution and prevent aggregation, ensuring that energetic particles contribute to energy density without forming agglomerates that would slow gas flow.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces ignition delay and two-phase flow losses, leading to increased rocket performance by ensuring efficient hypergolic ignition and improved combustion characteristics, while using environmentally friendly propellants.
Implementation Method 1
The decomposition process of hydrogen peroxide occurs mainly on the surface area of the catalytic/reactive particles so that the inner volume does not contribute to the reaction or, in other words, the particles are not fully combust or combust in a lower rate
Implementation Method 2
The commonest catalytic and reactive additives for the decomposition of hydrogen peroxide are complexes of transition metal salts composed of high atomic weight atoms (such as manganese, copper and iron) and metal hydrides
Implementation Method 3
The decomposition process of hydrogen peroxide occurs mainly on the surface area of the catalytic/reactive particles
Implementation Method 4
for reducing the ignition delay time, namely, the time interval between the contact of the fuel and the oxidizer and their ignition moment, a large quantity of catalytic/reactive additives may be required
Data Source
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AI summary
The present invention provides a particle and a composition for e.g., hypergolic ignition of rocket propellant. The disclosed particle and the composition comprise an energetic fuel additive and an ignition agent wherein the ignition agent is deposited on a surface of the particle.