• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.4
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• pp.583-592
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• 2001

The combustion characteristics of the hybrid catalytic(catalytic+thermal) combustor with a lean methane-air mixture on platinum catalyst were investigated numerically using a 2-D boundary layer model with detailed homogeneous and heterogeneous chemistries. for the more accurate calculations, the actual surface site density of monolith coated with platinum was decided by the comparison with experimental data. It was found that the homogeneous reactions in the monolith had little effect on the change of temperature profile, methane conversion rate and light off location. However, the radicals such as OH and CO were produced rapidly at exit by homogeneous reactions. The effect of operation conditions such as equivalence ratio, temperature, velocity, pressure and diameter of the monolith channel at the entrance were studied. In thermal combustor, the production of N$_2$O was more dominant than that of NO due to the relative importance of the reaction N$_2$+O(+M)→N$_2$O(+M). Finally the productions of CO and NOx by amount of methane addition were studied.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.267-267
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• 2012

$TiO_2$-Ni inverse catalysts were prepared using atomic layer deposition (ALD) process and catalytic $CO_2$ reforming of methane (CRM) reaction over catalysts (either bare Ni or $TiO_2$ coated-Ni particles) were performed using a continuous flow reactor at $800^{\circ}C$. $TiO_2$-Ni inverse catalyst showed higher catalytic reactivity at initial stage of CRM reactions at $800^{\circ}C$ comparing to bare Ni catalysts. Moreover, catalytic activity of $TiO_2$/Ni catalyst was kept high during 13 hrs of the CRM reactions at $800^{\circ}C$, whereas deactivation of bare Ni surface was started within 1hr under same conditions. The results of surface analysis using SEM, XPS, and Raman showed that deposition of graphitic carbon was effectively suppressed in a presence of $TiO_2$ nanoparticles on Ni surface, thereby improving catalytic reactivity and stability of $TiO_2$/Ni catalytic systems. We suggest that utilizing decoration effect of metal catalyst with oxide nanoaprticles is of great potential to develop metal-based catalysts with high stability and reactivity.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.99-105
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• 2001

For the design of selective catalytic reactors of NOx by $NH_3$, engineering approach can be performed to determine the reactor shape, mixing device and $NH_3$ injection system. This study shows the optimization of guide vanes to improve the flow pattern near the catalyst layer of SCR in a untility boiler. By varying their spacings and shapes, flow performance of guide vanes was analyzed to achieve an uniform velocity distribution which increases the NOx convesion efficiency, and a flow direction normal to the layer which minimises the erosion by the dust in the flue gas. Including these results, experimental and numerical studies for the SCR design were discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1266-1269
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• 2007

Polycrystalline silicon (poly-Si) films were prepared directly on plastic substrates at a low (< $200^{\circ}C$) by using Catalytic Chemical Vapor Deposition (Cat-CVD) technique without subsequent annealing steps. Surface roughness of the poly-Si layer and the density of the gate dielectric layer were found to be influential to the TFT performance.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.317.2-317.2
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• 2013

Ultrathin oxide encapsulated metal-oxide hybrid nanocatalysts have been fabricated by a soft chemical and facile route. First, SiO2 nanoparticles of 25~30 nm size have been synthesized by modified Stobber's method followed by amine functionalization. Metal nanoparticles (Ru, Rh, Pt) capped with polymer/citrate have been deposited on functionalized SiO2 and finally an ultrathin layer of TiO2 coated on surface which prevents sintering and provides high thermal stability while maximizing the metal-oxide interface for higher catalytic activity. TEM studies confirmed that 2.5 nm sized metal nanoparticles are well dispersed and distributed throughout the surface of 25 nm SiO2 nanoparticles with a 3-4 nm TiO2 ultrathin layer. The metal nanoparticles are still well exposed to outer surface, being enabled for surface characterization and catalytic activity. Even after calcination at $600^{\circ}C$, the structure and morphology of hybrid nanocatalysts remain intact confirm the high thermal stability. XPS spectra of hybrid nanocatalyst suggest the metallic states as well as their corresponding oxide states. The catalytic activity has been evaluated for high temperature CO oxidation reaction as well as photocatalytic H2 generation under solar simulation. The design of hybrid structure, high thermal stability, and better exposure of metal active sites are the key parameters for the high catalytic activity. The maximization of metal-TiO2 interface interaction has the great role in photocatalytic H2 production.

• Advances in aircraft and spacecraft science
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• v.5 no.5
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• pp.581-594
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• 2018

This paper is the follow-on of a previous paper by the author where it was pointed out that the forthcoming, manned exploration missions to Mars, by means of complex geometry spacecraft, involve the study of phenomena like shock wave-boundary layer interaction and shock wave-shock wave interaction also along the entry path in Mars atmosphere. The present paper focuses the chemical effects both in the shock layer and on the surface of a test body along the Mars orbital entry and compares these effects with those along the Earth orbital re-entry. As well known, the Mars atmosphere is almost made up of Carbon dioxide whose dissociation energy is even lower than that of Oxygen. Therefore, although the Mars entry is less energized than the Earth re-entry, one can expect that the effects of chemistry on aerodynamic quantities, both in the shock layer and on a test body surface, are different from those along the Earth re-entry. The study has been carried out computationally by means of a direct simulation Monte Carlo code, simulating the nose of an aero-space-plane and using, as free stream parameters, those along the Mars entry and Earth re-entry trajectories in the altitude interval 60-90 km. At each altitude, three chemical conditions have been considered: 1) gas non reactive and non-catalytic surface, 2) gas reactive and non-catalytic surface, 3) gas reactive and fully-catalytic surface. The results showed that the number of reactions, both in the flow and on the nose surface, is higher for Earth and, correspondingly, also the effects on the aerodynamic quantities.

• Journal of the Korean Ceramic Society
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• v.52 no.3
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• pp.221-223
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• 2015

In this work, we report on the preparation of the anodically-grown $TiO_2$ nanotube arrays sensitized with $In_2S_3$ nanoparticles by using the SILAR (successive ionic layer adsorption and reaction) process. We evaluate the photo-catalytic properties of the prepared hetero-structures under visible-light illumination. The results reveal that the $TiO_2/In_2S_3$ system has enhanced photo-catalytic characteristics including higher chopping height. Improved performance of the heterojunction is attributed to the narrower band gap of $In_2S_3$ and its favorable position within the conduction band relative to that of $TiO_2$.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.05a
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• pp.59-59
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.156.1-156
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• 2000

• Journal of the Korea Society of Computer and Information
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• v.22 no.1
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• pp.63-69
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• 2017

In this paper, we propose a method to optimize the geometry and installation position of the mixer in the selective catalytic reduction (SCR) system by computational fluid dynamic(CFD). Using the commercial CFD software of CFD-ACE+, the flow dynamics of the flue gas was numerically analyzed for improving the injection uniformity of the reduction agent. Numerical analysis of the mixed gas heat flow into the upstream side of the primary SCR catalyst layer was performed when the denitrification facility was operated. The characteristics such as the flow rate, temperature, pressure loss and ammonia concentration of the mixed gas consisting of the flue gas and the ammonia reducing gas were examined at the upstream of the catalyst layer of SCR. The temperature difference on the surface of the catalyst layer is very small compared to the flow rate of the exhaust gas, and the temperature difference caused by the reducing gas hardly occurs because the flow rate of the reducing gas is very small. When the mixed gas is introduced into the SCR reactor, there is a slight tendency toward one wall. When the gas passes through the catalyst layer having a large pressure loss, the flow angle of the exhaust gas changes because the direction of the exhaust gas changes toward a smaller flow. Based on the uniformity of the flow rate of the mixed gas calculated at the SCR, it is judged that the position of the test port reflected in the design is proper.