• Clean Technology
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• v.24 no.4
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• pp.371-379
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• 2018

The objective of this study is to develop a platinum/hexaaluminate pellet catalyst for the decomposition of eco-friendly liquid propellant. Pellet catalysts using hexaaluminate prepared by ultrasonic spray pyrolysis as a support and platinum as an active metal were prepared by two methods. In the case of the pellet catalyst formed by loading the platinum precursor onto the hexaaluminate powder and then adding the binder (M1 method catalyst), the mesopores were well developed in the catalyst after calcination at $550^{\circ}C$. However, when this catalyst was calcined at $1,200^{\circ}C$, the mesopores almost collapsed and only a few macropores existed. On the other hand, in the case of a catalyst in which platinum was supported on pellets after the pellet was produced by extrusion of hexaaluminate (M2 method catalyst), the surface area and the mesopores were well maintained even after calcination at $1,200^{\circ}C$. Also, the catalyst prepared by the M2 method showed better heat resistance in terms of platinum dispersion. The effects of preparation method and calcination temperature of Pt/hexaaluminate pellet catalysts on the decomposition of liquid propellant composed mainly of ammonium dinitramide (ADN) or hydroxyl ammonium nitrate (HAN) were investigated. It was confirmed that the decomposition onset temperature during the decomposition of ADN- or HAN- based liquid propellant could be reduced significantly by using Pt/hexaaluminate pellet catalysts. Especially, in the case of the catalyst prepared by the M2 method, the decomposition onset temperature did not show a large change even when the calcination temperature was raised at $1,200^{\circ}C$. Therefore, it was confirmed that Pt/ hexaaluminate pellet catalyst prepared by M2 method has heat resistance and potential as a catalyst for the decomposition of the eco-friendly liquid propellants.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.406-408
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• 2017

Ammonium dinitramide (ADN) Low toxicity monopropellant based 1N class thruster and test equipment were developed. Compared with the hydrazine which used in existing satellite thruster, ADN is easy to handle and has excellent physical characteristics such as density and specific impulse. Due to these characteristics, ADN is attracting attention as an eco-friendly propellant. In this paper, 1N class thruster and thrust measurement system was designed for performance testing of ADN monopropellant. The composition of the propellant for the design and experiment was set at 11.2: 25.4: 63.4 for each of Methanol: $H_2O$: ADN.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.558-565
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• 2017

Recently, there has been a tendency to lead the private sector in the launch vehicle market, and as the market has become saturated, efforts are being made to reduce the launch cost. Advanced countries in space development have promoted manned long-range space exploration plans. As oxygen/methane is more efficient, lower cost, and eco-friendly than typical propellants, and can be produced locally on an alien planet, it is the most suitable next-generation propellant to meet this trend. Now methane engine development is accelerating due to changes in international conditions and corporate environment. It is also expected to develop a methane engine in order to survive in this global trend and to keep up with the launch vehicle market in the future.

• Clean Technology
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• v.25 no.3
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• pp.256-262
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• 2019

Hydroxylammonium nitrate (HAN)-based liquid propellants are attracting attention as environmentally friendly propellants because they are not carcinogens and the combustion gases have little toxicity. The catalyst used to decompose the HAN-based liquid propellant in a thruster must have both low temperature activity and high heat resistance. The objective of this study is to prepare an Ru/alumina/metal foam catalyst by supporting alumina slurry on the surface of NiCrAl metal foam using a washing coating method and then to support a ruthenium precursor thereon. The decomposition activity of a HAN aqueous solution of the Ru/alumina/metal foam catalyst was evaluated. The effect of the number of repetitive coatings of alumina slurry on the physical properties of the alumina/metal foam was analyzed. As the number of alumina wash coatings increased, mesopores with a diameter of about 7 nm were well-developed, thereby increasing the surface area and pore volume. It was optimal to repeat the wash coating alumina on the metal foam 12 times to maximize the surface area and pore volume of the alumina/metal foam. Mesopores were also well developed on the surface of the Ru/alumina/metal foam catalyst. It was found that the metal form itself without the active metal and alumina can promote the decomposition reaction of the HAN aqueous solution. In the case of the Ru/alumina/metal foam-550 catalyst, the decomposition onset temperature was significantly lowered compared with that of the thermal decomposition reaction, and ${\Delta}P$ could be greatly increased in the decomposition of the HAN aqueous solution. However, when the catalyst was calcined at $1,200^{\circ}C$, the catalytic activity was lowered inevitably because the surface area and pore volume of the catalyst were drastically reduced and Ru was sintered. Further research is needed to improve the heat resistance of Ru/alumina/metal foam catalysts.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.1
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• pp.63-71
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• 2017

Liquid methane ($CH_4$)/oxygen ($O_2$) bipropellants have been recently considered as a next-generation propellant due to eco-friendly and non-toxic properties, low cost and high performance. In this study, the combustion characteristics of gaseous $CH_4/O_2$ nonpremixed coflow flames in a model combustor with variation of internal pressure are investigated through measuring the combustion stability limits and visualizing flames. Results show that the combustion stability limits are extended and the reaction region is widened with increasing internal pressure of the combustion chamber for fuel-rich condition.