• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.53-56
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• 1999

석탄 연소로 내에서는 어떠한 방식으로든 NH- 라디칼이 존재하게 된다. 즉, 배가스 처리 공정에서는 SNCR 방식에 의해 질소산화물 (NO) 저감할 경우 환원제로써 사용되는 암모니아 또는 요소와 같은 물질은 고온의 연소로에서 NH- 라디칼을 생성하게 되기도 하며, 순환유동층 연소로처럼 석탄을 원료로 사용하는 연소로에서는 석탄내에 포함되어 있는 N, H와 같은 원소들이 휘발하여 NH- 라디칼이 생성되기도 한다.(중략)

• Journal of the korean Society of Automotive Engineers
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• v.18 no.6
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• pp.33-39
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• 1996

최근 서울의 일부 지역에서는 오존 주의보에 의한 대기 오염의 수치가 발표되고 있어 이의 심각성이 대두되고 있다. 대기오염의 주범은 자동차이며, 자동차에서 주로 많이 배출되는 질소산화물(NOx)과 탄화수소(HC) 및 디젤자동차에서의 입자상 물질(PM: Particulate Matter)등이 대기환경에 미치는 영향이 크므로 이러한 물질의 저감에 대한 요구가 점차 강화되어가고 있다. 특히, 디젤 엔진이 가솔린 엔진에 비해 대기오염의 주원인이라는 편견이 일반적으로 널리 알려져 있지만, 이는 눈에 보이는 Black smoke에 대한 거부반응이 있다는 점이다. 실제로 디젤 엔진의 유해 배출 성분 중에서 NOx는 가솔린과 비슷한 수준이나 HC와 CO성분은 상당히 적게 배출되고 있다. 또한, 디젤 엔진은 연료 경제성 및 지구 온난화의 원인인 CO$_{2}$ 배출이 적다는 장점이 있으므로 디젤 엔진에서 많이 배출되는 성분으로서 입자상 물질(PM) 및 NOx를 줄이는 방안이 요구되고 있다. 이를 저감시키는 방법은 여러가지가 있으나 분사계 측면에서 전자제어식 고압 연료 분사가 요구되고 있으며 이의 개발 필요성에 대해서 논하기로 한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.150-155
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• 2012

Lean NOx Trap (LNT) catalysts are capable of reducing exhaust NOx emissions from diesel engines. LNT stores NOx in lean condition and exhausts N2 by reducing NOx in rich condition. NOx reduction characteristic of LNT catalysts using throttle position sensor and fuel injection timing control for light-duty diesel engine was investigated. In contrast to SCR system, LNT catalyst uses diesel fuel in resuctant. Also if the concentration of reductant is exceeded, excessive amount of reductant will slip throughout LNT and cause another emission problem. Thus LNT regeneration with precise engine control established that can make higher NOx conversion efficiency and lower fuel penalty, prevent another emission problem. NOx and reductant concentration were measured by the NOx sensor and Mexa7100D equipped inlet and outlet of catalyst. As a result of engine test, regeneration strategy has reached high of 77.8% NOx conversion efficiency according to engine operation condition. Moreover, we have proved that it is possible to use regeneration strategy of LNT within 5% fuel penalty.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.183-194
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• 2013

Liquid urea based SCR has been used in the market to reduce NOx in the exhaust emission of the diesel engine vehicle. This system has several problems at low temperature, which are freezing below $-12^{\circ}C$, solid deposit formation in the exhaust, and difficulties in dosing system at exhaust temperature below $200^{\circ}C$. Also, it is required complicated exhaust packaging equipment and mixer due to supply uniform ammonia concentration. In order to solve these issues, solid urea, ammonium carbonate, and ammonium carbamate are selected as ammonia sources for the application of solid SCR. In this paper, basic research on reaction rate of three ammonia-transporting materials was performed. TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) tests for these materials are carried out for various heating conditions. From the results, chemical kinetic parameters such as activation energy and frequency factor are obtained from the Arrhenius plot. Additionally, from test results of DSC (Differential Scanning Calorimeter) for these materials, chemical kinetic parameters using the Kissinger method are calculated. Activation energies of solid SCR from this experiment are compared with proper data of literature study, then obtained data of this experiment are used for the design of reactor and dosing system for candidate vehicle.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.967-972
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• 2013

A MILD (Moderate and Intense Low oxygen Dilution) combustion, which is effective in the reduction of NOx, is considerably affected by the recirculation flow rate of hot exhaust gas to the combustion furnace. The present study used the MILD combustor, which has coaxial cylindrical tube. The outside tube of the MILD combustor corresponds to the exhaust gas passage and the inner side tube is the furnace passage. A numerical analysis was accomplished to elucidate the characteristics of exhaust gas entrainment toward the inner furnace with the changes of coanda nozzle geometrical parameters, nozzle passage gap length, nozzle passage length, nozzle angle and expansion length. The optimal configuration of coanda nozzle for the best entrainment flow rate was gap length, 0.5 mm, expansion angle, 4o and expansion length, 146 mm. The nozzle passage length was irrelevant to the exhaust gas entrainement.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.308-311
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• 2011

The reaction mechanism of selective catalytic reduction of NOx over sewage sludge char impregnated with MnOx using $NH_3$ as the reducing agent was investigated. The active Mn phase was shown to be $Mn_3O_4$ from the XRD analysis. Adsorption was the dominant NOx removal mechanism at low temperatures below $150^{\circ}C$ although reduction reaction also contributed partly to the NOx removal at $100{\sim}150^{\circ}C$. The reaction rate constants of NOx removal over non-impregnated and MnOx-impregnated active chars were compared based on experimental results. The MnOx-impregnated char was shown to have a higher reaction rate constant and a higher NOx removal efficiency due to a higher collision coefficient and a lower activation energy. The activation energy for both chars was shown to be relatively low (10~12 kJ/mol) under the experimental conditions of this study.

• Journal of the Korean Institute of Gas
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• v.13 no.6
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• pp.21-28
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• 2009

The purpose of this study is to gain a better understanding of the effects of thermal stratification and partial fuel stratification on reducing the pressure-rise rate and emission in HCCI combustion. The engine is fueled with Di-Methyl Ether(DME) which has unique 2-stage heat release. Computational work is conducted with multi-zones model and detailed chemical reaction scheme. Calculation result shows that wider thermal stratification and partial fuel stratification prolong combustion duration and reduce pressure rise rate. But too wide partial fuel stratification increases CO and NOx concentration in exhaust gas, and decreases combustion efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1616-1623
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• 2001

A basic experimental study has been carried out to find out the design parameters of fuel 2-staging atomizers in order to reduce nitrogen oxides(NOx) rate emitted from the steam boilers used the liquid fuel. The heavy fuel oil(B-Coil) and fuel 2-staging Y-jet twin-fluid atomizers were adopted in this study. The results of this paper were obtained from the real as well as the model scale atomizers. In the case of model atomizers test, NOx reduction rate was strongly dependent on the staged fuel rate, but it was weakly dependent on the injection hole arrangement and air swirl conditions. The real scale atomizers was designed and manufactured on the base of these test results, and those was mounted and operated in the real boiler generates 185 ton steam per an hour. The reduction rate of the model and real plant was reached 10∼30% of base NOx by atomizers. but dust was sharply increased in the low O$_2$combustion region of the real plant.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.521-527
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• 2005

The effects of an urae injection at the exhaust pipe for a 4-cylinder DI(Direct Injection) diesel engine are investigated experimentally. The urea quantity was controlled by NOx quantity and MAF(Manifold Air Flow). The urea injection must be precisely metered and then I used the urea syringe pump. I have tested 4 kinds of items that were with the EGR base engine and without the EGR engine. Then I tested each urea-SCR(Selective Catalytic Reduction) system. As the results, I can caculate the SUF(Stoichiometric Urea Flow) and visualize the NOx results by variation of engine speed and engine load. Also, I can make the NOx map. Therfore, I knew that NOx reduction effects of the urea-SCR system without the EGR engine were better than the with EGR base engine except of low load and low speed.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.119.2-119.2
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• 2014

대기환경 규제가 강화됨에 따라 기존 기술 대비 획기적인 성능과 가격 경쟁력을 갖춘 새로운 대기환경 기술에 대한 수요가 지속적으로 요구되고 있다. 특히 최근에는 종래의 분진, 이산화황가스 및 질소산화물에 대한 규제와 더불어 지구온난화가스인 이산화탄소, 과불화화합물 (Perfluorocompounds, PFCs), 메탄가스 등에 대한 규제가 강화되면서 이에 대응할 수 있는 대기환경 기술의 수요가 늘고 있다. 한국기계연구원에서는 지난 10 여 년간 지구온난화가스이자 난분해성 가스인 메탄 및 PFCs 가스를 플라즈마 화학반응 공정을 통해 분해하는 연구를 수행해왔으며, 이를 바탕으로 산업에 적용할 수 있는 기술개발도 병행하여 수행하였다. 현재 개발된 기술 가운데 일부는 산업에 실제로 적용되고 있으며, 이를 통해 산업현장에서는 지구온난화가스는 물론 질소산화물과 같은 다른 종류의 규제물질도 동시에 저감할 수 있었다. 본 발표에서는 플라즈마를 활용하여 난분해성 가스인 메탄과 PFCs를 분해하는 기술의 특성을 살펴보았으며, 이를 바탕으로 산업현장에 적용된 대기환경기술이 어떻게 활용되고 있는지를 소개하고 있다. 본 발표에서 다루게 될 플라즈마 발생기술은 펄스 코로나, 유전체장벽방전, 마이크로웨이브 토치, 아아크 토치 등이며, 플라즈마 발생조건은 수 torr 이하의 진공조건부터 및 대기압 조건에 이르고 있다.