• Title/Summary/Keyword: NOx 분포

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NUMERICAL STUDY ON THE MIXER TYPE OF UREA-SCR SYSTEM FOR FLOW MIXING IMPROVEMENT (Urea-SCR 시스템의 유동혼합 개선을 위한 혼합기 형상에 관한 수치적 연구)

  • Lee, J.W.;Choi, H.K.;Yoo, G.J.;Kim, W.S.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.368-375
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    • 2010
  • To alleviate NOx emission, a variety of approaches has been applied. In marine diesels, the application of SCR systems has been considered an effective exhaust aftertreatment method for NOx emission control. Most current SCR systems use a various catalyst for the reaction of ammonia with NOx to form nitrogen and water. In theory, it is possible to achieve 100% NOx if the NH3-to-NOx ratio is 1:1. However, the reaction has a limited non-uniformity of the exhaust gas flow and ammonia concentration distribution. Therefore it is necessary to investigate the optimum flow conditions. In order to achieve uniform flow at monolith front face, we are equipped with a various mixed device. In this paper, it is presented that the mixed devices play an important role improvement of flow patterns and particle distributions of NH3 by numerical simulation.

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NUMERICAL STUDY ON THE MIXER TYPES OF UREA-SCR SYSTEM FOR FLOW MIXING IMPROVEMENT (Urea-SCR 시스템에서 유동혼합 개선을 위한 혼합기 형상에 관한 수치적 연구)

  • Lee, J.W.;Choi, H.K.;Yoo, G.J.
    • Journal of computational fluids engineering
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    • v.15 no.4
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    • pp.9-16
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    • 2010
  • To alleviate NOx emission, a variety of approaches has been applied. In marine diesels, the application of SCR systems has been considered an effective exhaust aftertreatment method for NOx emission control. Most current SCR systems use a various catalyst for the reaction of ammonia with NOx to form nitrogen and water. In theory, it is possible to achieve 100% NOx if the $NH_3$-to-NOx ratio is 1:1. However, the reaction has a limited non-uniformity of the exhaust gas flow and ammonia concentration distribution. Therefore, it is necessary to investigate the optimum flow conditions. In order to achieve uniform flow at monolith front face, we are equipped with a various mixed devices. In this paper, it is presented that the mixed devices play an important role improvement of flow patterns and particle distributions of $NH_3$ by numerical simulation.

A Study on NOx Removal Efficiency Depending on Electrode Configurations of Silent Discharges (무성방전 플라즈마 전극구조에 대한 질소산화물 제거효율 연구)

  • Hyung-Taek Kim;Young-Sik Chung;Myung-Whan Whang;Elena. A. Filimonova
    • Journal of the Korean Society of Safety
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    • v.17 no.3
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    • pp.112-117
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    • 2002
  • A comparative investigation of an experimental and a simulation of chemical kinetics for NOx removal from silent(dielectric-barrier) discharges is presented. Several types of dielectric-barrier discharges were implemented depending upon the configuration of electrodes. The simulation was based on an approximate mathematical model for plasma cleaning of waste gas. The influence of non-uniform distributions of species due to the production of primary active particles in the streamer channel was taken into account. A comparison of observed experimental to the calculated removal efficiency of NOx showed acceptable agreement.

Vertical Ozone Distributions over the Seoul Metropolitan Area in June (서울지역 6월 오존의 연직분포)

  • 김유근;이화운;오인보;정우식;송상근;임윤규;황미경
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2003.11a
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    • pp.113-114
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    • 2003
  • 도시지역 하층대기의 오존 연직분포는 지표부근의 NOx배출의 영향과 대기경계층의 일변화 및 구조적 특성에 의해 시·공간적으로 큰 변화를 나타낸다. 일반적으로 야간에는 역전층 내의 건성침적과 NOx 적정작용에 의해 오존농도가 감소하며, 하층 안정층과 분리되어 있는 잔류층(residual layer)의 오존농도와 큰 차이를 보이게 된다. 아울러 일출 후 안정층 파괴와 혼합고 성장에 의해 지표부근의 오존농도가 증가하고 연직적으로 비교적 일정한 오존분포가 나타난다(Zang et al., 1998; Berkowitz et al., 2000). (중략)

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Temporal and Spatial Distributions of PM10, NOx and O3 around the Road (도로 주변의 PM10, NOx 및 O3의 시공간적 농도 분포 연구)

  • Kwon O-Yul;An Young-Sang
    • Journal of Korean Society for Atmospheric Environment
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    • v.22 no.4
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    • pp.440-450
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    • 2006
  • PM10, NOx, and $O_3$ were measured at six locations, of which each three is horizontally and vertically distributed respectively, in an apartment complex around the heavily traffic road. Those were measured seven times a day with two hours interval starting from 8 o'clock in the morning for 15 days during May 2005 $\sim$ September 2005. PM10 and NOx showed high concentrations in rush hours while low concentrations in midday due to the direct emissions from automobiles in operation. Temporal variations of 01 showed very much similar trend appeared in normal urban atmospheres. The spatial distributions of PM10, NOx and $O_3$ showed that almost all of concentrations were higher in a row of Roadside > Surface at 130 m apart from the road > Surface at 230 m apart from the road > 3rd floor of apartment building > 15th floor of apartment building > 27th floor of apartment building. Model equations, which can project spatial concentration distributions, were constructed by combining the horizontal and the vertical linear regression equations derived from six mean values corresponding to six measuring locations. According to inter-comparison of PM10, NOx, and $O_3$ with the constructed model equations, concentration gradients were higher in a row of Vertical direction of NOx > Vertical direction of PM10 > Horizontal direction of NOx > Horizontal direction of PMIO > Vertical direction of $O_3$ > Horizontal direction of $O_3$. Why concentration gradient of particulate PM10 is lower than that of gaseous NOx is in question, and should be studied.

특집:녹색선박 SCR시스템 기술개발 현황 - Urea 분사 제어장치 설계

  • Jeong, Gyeong-Yeol;Im, Byeong-Ju;Park, Chang-Dae;Choe, Dae-Seok
    • 기계와재료
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    • v.24 no.2
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    • pp.62-71
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    • 2012
  • 세계적으로 NOx 저감 및 규제치의 강화로 인해 디젤기관에서 발생되는 NOx 제거에 대한 연구가 활발히 진행 중이며, 암모니아 환원제와 배출가스의 NOx를 혼합하여 촉매 존재하에서 NOx를 제거하는 시스템이 개발되고 있다. 대부분 암모니아를 보관성이 용의한 요소(Urea) 수용액으로 대체하여 배기관 내에 직접 요소수를 분사하며 요소 수용액이 고온의 배기가스에 의해 증발되어 암모니아를 환원시키며, 촉매를 통하여 탈질을 하는 Urea-SCR 시스템을 채택하고 있다. 따라서 촉매전단에서 요소수가 완전히 증발되고, 또한 촉매 입구에서 요소수의 증발로 인해 환원된 암모니아의 분포도 균일해야 함으로 Urea-SCR 시스템이 배기가스 유동 및 온도에 최적화된 분무특성을 가지는 분사제어 시스템을 제시하고자 한다.

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Combustion Characteristics of Coal-Fired Boiler Depending on the Variations in Combustion Air Supply Method (미분탄 보일러의 연소용 공기공급 변화에 따른 노내 연소상태 해석)

  • Seo, San-Il;Park, Ho-Young;Kang, Dong-Soo;Jeong, Dong-Hae
    • Journal of Energy Engineering
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    • v.19 no.3
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    • pp.156-162
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    • 2010
  • 3-D CFD(Computational Fluid Dynamics) work were carried out to investigate the combustion characteristics in a boiler depending on the variations in air supply condition. For the gas temperature, $O_2$, NO, SOx at the outlet of economizer, the predicted values were been compared with the measured data. With the verified CFD model, the effects of air flow rates through SOFA(Separated Over Fire Air) and CCOFA(Closed Coupled Over Fire Air) on the combustion behavior in a boiler were simulated, and the distributions of NOx and gas temperature were mainly compared each other. The change in SOFA air flow rate gave the more sensitive effect on NOx than that in CCOFA. The distributions of gas temperature at convection path are differed with the changes in SOFA and CCOFA flow rate, so the combustion modification such as yaw anlge adjustment are required to get an enhanced gas temperature distribution.

Study on the Optimal Injection Condition for HC-LNT Catalyst System for Diesel Engines with a Gasoline PFI Type Injector (가솔린 인젝터를 디젤엔진용 HC-LNT 촉매에 적용하기 위한 최적 분사 조건에 관한 연구)

  • Oh, Jung-Mo;Mun, Woong-Ki;Kim, Ki-Bum;Lee, Jin-Ha;Lee, Ki-Hyung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.2
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    • pp.121-127
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    • 2011
  • NOx (Nitrogen Oxide) reduction system periodically needs a rich or stoichiometric operating condition to reduce NOx. A new method that optimizes the control of external HC injection into a diesel exhaust pipe for HC-type LNT (Lean NOx Trap) catalyst system has been developed. In this paper, these catalysts are called HC-LNT catalysts. The concentration and amount of HC can be controlled by controlling the external injection. In this study, we investigated the relationship between the spray behavior of hydrocarbons injected into the transparent exhaust pipe and NOx reduction characteristics. From the results of this experiment, we obtained useful information about the optimum injection and position of HC injector to the exhaust pipe. Further, we obtained useful information about the optimal injection condition for an HC-LNT catalyst system with a gasoline PFI (port fuel injection) typeinjector.

Dependence of Nanoparticle and Combustion Characteristics of Gasoline Direct Injection Engines on Coolant Temperature (GDI 엔진의 냉각수온에 따른 연소성능 및 입자상 물질 배출 특성)

  • Lee, Hyo-Keun;Choi, Kwan-Hee;Myung, Cha-Lee;Park, Sim-Soo;Park, Jong-Il;Han, Seung-Kook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.2
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    • pp.131-136
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    • 2012
  • This paper investigated the combustion and exhaust gas characteristics of gasoline direct injection engines for various cooling water temperature. The engine-out nanoparticle emission number and size distribution were measured by a DMS-500 equipped upstream of the catalyst. A CLD-400 and an HFR-400 were equipped at the exhaust port to analyze the cyclic NOx and total hydrocarbon emission characteristics. The results showed that the nanoparticle emission number greatly increased at low coolant temperatures and that the exhaust mainly contained particulate matter of 5.10 nm. THC also increased under low temperature conditions because of fuel film on the combustion chamber. NOx emissions decreased under high temperature conditions because of the increase in internal exhaust gas recirculation. In conclusion, an engine management system control strategy for driving coolant temperature up rapidly is needed to reduce not only THC and NOx but also nanoparticle emissions.

Flame Structure of Moderately Turbulent Combustion in the Opposed Impinging Jet Combustor (대향분출화염의 분산화학반응 화염구조와 NOx 저감기구)

  • 손민호;조용진;윤영빈;이창진
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.10
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    • pp.1387-1393
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    • 2002
  • The measurement of velocity and stain rate field has been conducted in opposed impinging jet combustion. When a smaller diameter (5mm) orifice of pre-chamber was used, previous studies had reported that the combustion phase showed a shift from weak turbulent combustion to moderate turbulent combustion in the modified Borghi Diagram. In the case with smaller orifice diameter (5mm), NOx emission was substantially reduced by a factor 1/2 while the combustion pressure remains at the same as that in the conventional combustion. Hence, in this study, the experiment setup using PIV technique was designed to identify the relation of the strain rate distribution and NOx reduction associated with moderate turbulent combustion. As a result, it was found that the highly strained pockets are widely distributed during the combustion in the middle of chamber when the orifice diameter is 5mm. And the corresponding PDF distribution of strain rates she was the smoothly distributed strain .ate within the range of |$\pm$1000| (1/sec) rather than a spike shape about zero point. This is the unique feature observed in the combustion with 5mm orifice diameter. Therefore, it can be concluded that the substantial NOx reduction in opposed impinging combustor is mainly attributed to the strain rate distribution within the range of |$\pm$1000|resulting in the combustion phase shift to moderate turbulent combustion.