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Syaiful,Myung-whan Bae 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Selective catalytic reduction (SCR) is a leading after-treatment technology for reducing NOx emissions among exhaust gases in combustors. The purpose of this study is to develop SCR catalytic filter system for reducing NOx and soot emissions simultaneously in diesel combustion devices. SCR catalysts are used to reduce NOx emissions. And the novel catalytic filters inside SCR system devised by authors are specially designed and manufactured to reduce soot particles. The working temperature distribution along the surface of SCR catalytic filter is one of the important parameters for converting NOx to N₂ by reacting with the injected ammonia. The working temperature distribution and velocity field of gaseous flow in SCR device are investigated by numerical simulation in this study. Three catalytic filters are vertically located to the face of mixing length inside SCR system at 120° interval of horizontal section. In order to predict turbulent flow, k - ε standard turbulent model is applied. Ammonia is radially injected perpendicular to the exhaust gas flow in inlet pipe and mixes with exhaust gases in the mixing area. A heater is implemented in this simulation to heat up the gaseous flow reaching for the working temperature of SCR MnO₂-V₂O?-WO₃/TiO₂/SiC catalytic filters. The results of this study show that the working temperature distribution around each catalytic filter is different because it is influenced by velocity field of gaseous flow in mixing area of SCR device. Thus one can conclude that NO conversion in each catalytic filter of SCR system is different due to the variation of working temperature distribution.
Syaiful,Myung-whan Bae,Kichang Im 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
Selective catalytic reduction (SCR) is a successful technique to reduce NOx emissions in diesel exhaust gases. The aim of current study is to develop a SCR catalytic filter device for reducing NOx and soot emissions simultaneously in diesel combustors. SCR catalysts are used to reduce NOx emissions, and the novel catalytic filters inside SCR system are especially designed and manufactured to reduce soot particles. NH₃ or urea (which is converted to ammonia) is injected into exhaust stream then reacts with NOx emissions over the catalyst surface of SCR device, so that a uniform distribution of NH₃ is one of the challenges in the novel design of SCR device in order to attain NOx conversion and reduce NH₃ slip optimally. In this study, three catalytic filters with 120° interval are vertically mounted under the horizontal plate. Ammonia is injected radially perpendicular into the inlet main flow. The ammonia concentration in the SCR catalytic filter device is investigated by numerical simulation. Gaseous flow in SCR catalytic filter device is modeled as laminar and turbulent flow by varying the Reynolds numbers. The results show that there is the small influence of circulations on the ammonia concentration near the inlet domain at the low Reynolds number. On the contrary, the high influence of circulations on the ammonia concentration is observed at high Reynolds number.
Syaiful,Myung-whan Bae 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Selective catalytic reduction (SCR) and diesel particulate filter (DPF) are a potential way to diminish NOx and soot emissions from exhaust gas of diesel combustors, respectively. The use of these methods in the automotive application requires more space and has a higher pressure drop. SCR catalytic filter system is a novel exhaust gas after-treatment method that can reduce NOx and soot emissions simultaneously. This device can save space and the use of SiC DIA-Schumalith filter has a low pressure drop. As generally SCR device, the performance of SCR catalytic filter system depends on the various additional factors. Two factors discussed in this study are uniformity of flow which corresponds to the homogeneity of NH3/NOx mixture, and the catalyst surface temperature which is important factor to achieve an optimal NOx conversion. The amount of ammonia must be controlled with the amount of NOx. If the amount of ammonia is much higher than that of NOx, the ammonia slip will be formed. On the other hand, if the amount of ammonia is less than that of NOx, the catalyst is not fully active. Therefore, a uniformity of ammonia mass distribution is studied numerically in this paper in which it depends on the velocity field of gaseous flow in SCR device. As the ammonia mass distribution, a temperature distribution in SCR device is discussed in this study to reach the working temperature of catalyst used in the SCR catalytic filter system. A heater is set up at the bottom wall of SCR device to adjust the temperature of gaseous flow in the range of working temperature. However, the heat addition influences the velocity field of gaseous flow in SCR device and affects the ammonia mass distribution, eventually. Hence, the effect of heat addition on the uniformity of ammonia mass distribution is investigated in this paper. The influence of different injection placements on the ammonia mass distribution is also discussed. The results show that the ammonia mass distribution is more uniform for the injector directed radially perpendicular to the main flow of inlet at the gravitational direction than that at the side wall for turbulent flows (Re = 4255). The injection placement has a small effect on the uniformity of ammonia mass distribution in the case of laminar flow (Re = 64). It is also found that the mixing index decreases as increasing the heating temperature in the case of ammonia injected at the side wall. The result also shows that the catalyst surface temperature at the laminar flow is higher than that at turbulent flow.
Myung-whan Bae,Syaiful 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Selective catalytic reduction (SCR) is known as one of promising methods for reducing NO<SUB>x</SUB> emissions in diesel exhaust gases. NO<SUB>x</SUB> emissions react with ammonia in the catalyst surface of SCR system at working temperature of catalyst. The problem arises, in this case, when the diesel exhaust gas temperature is low. To overcome this problem, catalytic filters have been developed by many researchers which can be optimally operated at low temperature. However, if the exhaust gas temperature is too low, implementing a heater is necessary for keeping the adequate reacting temperature. In this study, to raise the reacting temperature when the exhaust gas temperature is too low, a heater is located at the bottom of SCR reactor. At an ambient temperature, ammonia is radially injected perpendicular to the exhaust gas flow at inlet pipe and uniformly mixed in the mixing area after impinging against the wall. To predict the turbulent model inside the mixing area of SCR system, the standard κ-ε is applied. This work investigates numerically the effects of induced heat on the gaseous flow. The results show that the Taylor-Gortler type vortex is generated after the gaseous flow impinges the wall in which these vortices influence the temperature distribution. The addition of heat disturbs the flow structure in bottom area and then stretching flow occurs. Vorticity strand is also formed when heat is continuously increased. Constriction process takes place, however, when a further heat input over a critical temperature is increased and finally forms shed vortex which is disconnected from the vorticity strand. The strong vortex restricts the heat transport in the gaseous flow.
Manivasagan, Panchanathan,Alam, Moch Syaiful,Kang, Kyong-Hwa,Kwak, Minseok,Kim, Se-Kwon Springer-Verlag 2015 BIOPROCESS AND BIOSYSTEMS ENGINEERING Vol.38 No.6
<P>Advancement of biological process for the synthesis of bionanoparticles is evolving into a key area of research in nanotechnology. The present study deals with the biosynthesis, characterization of gold bionanoparticles by Nocardiopsis sp. MBRC-48 and evaluation of their antimicrobial, antioxidant and cytotoxic activities. The gold bionanoparticles obtained were characterized by UV-visible spectroscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscopy (TEM). The synthesized gold bionanoparticles were spherical in shape with an average of 11.57 +/- A 1.24 nm as determined by TEM and dynamic light scattering (DLS) particle size analyzer, respectively. The biosynthesized gold nanoparticles exhibited good antimicrobial activity against pathogenic microorganisms. It showed strong antioxidant activity as well as cytotoxicity against HeLa cervical cancer cell line. The present study demonstrated the potential use of the marine actinobacterial strain of Nocardiopsis sp. MBRC-48 as an important source for gold nanoparticles with improved biomedical applications including antimicrobial, antioxidant as well as cytotoxic agent.</P>