• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.89-96
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• 2006

In this study, fluid flow and thermal characteristics in a catalyst bed for nitrous oxide catalytic decomposition which is introduced as a hybrid rocket ignition system for small satellites were theoretically considered. To analyze the thermal phenomena of the catalyst bed, a so-called porous medium approach has been opted for modeling the honeycomb geometry of the catalyst bed. Using a Brinkman-extended Darcy model for fluid flow and the one-equation model for heat transfer, the analytical solutions for both velocity and temperature distributions in the catalyst bed are obtained and compared with experimental data to validate the porous medium approach. Based on the analytical solutions, parameters of engineering importance are identified to be the porosity of the catalyst bed, effective volumetric ratio, the ratio of the radius of the catalyst bed to the radius of a pore, heat flux generated by a heater, and pumping power. Their effects on thermal phenomena of the catalyst bed are studied.

• Journal of the Korean Chemical Society
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• v.30 no.1
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• pp.118-125
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• 1986

A small scale combustion unit was built to evaluate the CO suppression effects by various chemical additives added to coal briquettes. Among the additives tested comprising various transition metal compounds with catalytic activities, natural minerals and oxidizing agents, the copper component has shown the best CO suppression effect, and in particular, copper oxide dispersed on porous supports such as ${\gamma}-Al_2O_3$ was most effective. For instance, 0.5% of copper added to coal briquettes in this way bas exhibited 1.4 % CO in the combustion gas at the ignition and beginning stage of combustion and 0.3 % CO at the final stage. The effects of calcium compounds on the fixation of sulfur in coal were also evaluated to reduce the contents of sulfur compounds in the combustion gases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.156-164
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• 2010

As part of preliminary study for development of 1,200 N-class bipropellant rocket engine with the concentrated hydrogen peroxide, bipropellant engine elements were designed and experimentally tested. The catalysts of $MnO_2$ and $MnO_2$ added Pb as an addictive were compared to achieve high decomposition performance and the catalytic reactor with $MnO_2$ added Pb was designed and its decomposition efficiency of 97.2% was achieved. The autoignition tests of kerosene by decomposed hydrogen peroxide were carried out under various equivalence ratios to ignite without additional ignition sources. Autoignition were achieved in all experimental conditions and $C^*$ efficiencies at each condition were at or above 90%. From the measured thrust results, the highest value was 830 N which is in corresponds with 1,035 N at vacuum level using 94.1% theoretical $I_{sp}$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.165-171
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• 2010

The Homogeneous Charge Compression Ignition (HCCI) engine concept allows for both NOx and particulate matter to be reduced simultaneously, and it is a promising way to meet the next environmental challenges. Unfortunately, HCCI combustion often increases CO and HC emissions. The development of oxidation catalyst (OC) requires high conversion efficiency for CO and HC at low temperature. Conventional oxidation catalyst technologies may not be able to convert these emissions because of the saturation of active catalytic sites. The OC used in this study was 600 cpsi cordierite. Three kinds of OC with different amounts of Pt and Pd were used. The influence of the space velocity (SV), $H_2O$ and $O_2$ concentration was also studied. All types of OCs were found to have over 90% CO conversion efficiencies at $170^{\circ}C$. When in the presence of water vapor, CO conversion was increased, but $C_3H_8$ conversion was decreased. The performance of the OC was not influenced by initial the HC concentration. The 2Pt/Pd catalyst was better in terms of thermal aging than the Pt-only catalyst. The $LOT_{50}$ of both fresh and aged OC was increased with increasing SV and with the presence of $H_2O$.