• 한국자동차공학회논문집
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• 제20권5호
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• pp.36-43
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• 2012

In this work the mixing and flow characteristics of a vane-type static mixer were investigated numerically for the reduction of NOx in the SCR-system of the diesel engines. The mixer was located in the 57 times pipe diameter away from the inlet. The analysis were performed by changing such various parameters as vane shape, angles, blockage ratio and location of the vane. The flow structure through the mixer was characterized by uniformity index and pressure drop. The results show that uniformity index and pressure coefficient are substantially influenced by the vane shape, angle, blockage ratio and position of the vane of the mixer.

• 동력기계공학회지
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• 제9권4호
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• pp.77-82
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• 2005

Bellows is a familiar component in piping systems as it provides a relatively simple means of absorbing thermal expansion and providing system flexibility. In routine piping flexibility analysis by finite element methods, bellows is usually considered to be straight pipe runs modified by an appropriate flexibility factor; maximum stresses are evaluated using a corresponding stress concentration factor. In this paper, the dynamic characteristics of bellows were investigated by Finite element methods. Using Anany program, the natural frequencies and evaluation of the reliability of bellows were also investigated.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.57-63
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• 2005

The effects of an urea injection at the exhaust pipe for a 4-cylinder DI(Direct Injection) diesel engine were investigated with the parameters such as urea-SCR(Selective Catalytic Reduction) and EGR system. The urea quantity was controlled by NOx quantity and MAF(Manifold Air Flow). The urea injection quantity can be controlled with the urea syringe pump, precisely. The effects of NOx reduction for the urea-SCR system were investigated with and without ECR engine, respectively. It was concluded that the SUF(Stoichiometric Urea Flow) is calculated and the NOx results are visualized with engine speed and load. Furthermore, the NOx map is made from this experimental results. It was suggested, therefore, that NOx reduction effects of the urea-SCR system without the EGR engine were better than that with the EGR engine except of low load and low speed.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.665-672
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• 2004

Chemical cleaning of boiler pipelines is necessary before the commissioning of thermal power plant after many years of construction. Fluid-Dynamic study for the chemical cleaning of boiler piplelines in Young-Heung thermal power plant is carried out. First, flow velocity necessary to sustain and exhaust solid particles in the vertical pipelines is calculated. Second, the flowrate necessary to make the calculated velocities in each vertical pipelines is calculated. Third, all the pipelines are analyzed with the Piping Systems Fluid Flow software to calculated the pressure loss in the pipelines. Finally, the operating point of the applied pump is calculated with the help of the same software.

• 설비공학논문집
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• 제16권3호
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• pp.273-279
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• 2004

A lab-scale fluidized bed heat exchanger for waste gas heat recovery is devised and tested. Compared to our previous works on fluidized bed type system with a single riser, the present heat exchanger system is featured by its multiple (four) risers to handle increased amount of exhaust gas. Particles are introduced to the main hot gas stream alongside the pipe circumference near riser inlets. The heat exchanger performance and pressure drop are evaluated through experiments for the present gas-to-water heat exchanger system.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권1호
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• pp.24-31
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• 2003

A new fluidized bed heat exchanger for exhaust gas heat recovery is do-veloped. Compared to the existing ones, the present heat exchanger system is featured by the particle fluidization method which does not depend on conventionally used baffle plate with holes and by the multiple downcomer tubes to extract heat energy from hot particles during the time particles moves down to be fed again to the hot gas line. Particles are introduced to the main hot gas stream alongside the pipe circumference. The heat exchanger performance and pressure drop are evaluated through experiments for the present gas-to-water heat exchanger system.

• 한국분무공학회지
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• 제24권3호
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• pp.122-129
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• 2019

Flow uniformity in aftertreatment system is an important factor in determining uniform catalytic reaction and filtration. In this study, variety types of DOC-DPF system design were analyzed to increase flow uniformity. For this analysis, ANSYS Fluent was used with porous media setup for DOC and DPF. Turbulent flow was modeled by standard $k-{\varepsilon}$ model excepting porous media. Uniformity index was utilized to evaluate the flow uniformity quantitatively. Reference design showed low velocity region because two large vortex were generated before baffle. When radius of DOC-DPF system was increased, exhaust pressure acting on the inlet decreases and velocity distribution was shifted to one side. When inlet pipe was set to axial center of DOC-DPF system velocity distribution was symmetric. However, flow was not dissipated until the front end of DOC and showed higher uniformity index. When the volume of DOC was reduced while fixed volume of entire DOC-DPF system and baffle plate is located downstream of the DOC-DPF system, there was improvement in uniformity index.

• 대한기계학회논문집B
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• 제34권8호
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• pp.755-760
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• 2010

본 연구는 승용 디젤엔진의 입자상 물질 배출특성에 관한 것으로써, 엔진에서 배출된 입자상 물질이 배기관 및 후처리장치인 디젤산화촉매와 매연여과장치를 통과할 때의 특성 변화를 파악하기 위하여 후처리장치 각각 전 후단 및 배기관에서 직접 측정하였다. 또한 다양한 엔진회전속도 및 부하조건에서 측정함으로써 입자상 물질 배출 맵을 구축하였으며, 디젤산화촉매 및 매연여과장치의 입자상 물질 저감효과에 대해 평가하였다. 뿐만 아니라 배기재순환율과 연료분사시기를 변경시켜 입자상 물질의 배출특성 변화를 파악하였다. 모든 시험에서 입자상 물질을 5~1000nm 크기까지 측정할 수 있는 DMS500을 이용하였다.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.136-144
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• 2010

Exhaust gas recirculation (EGR) is an emission control technology allowing significant NOx emission reduction from light-and heavy duty diesel engines. The future EGR type, dual loop EGR, combining features of high pressure loop EGR and low pressure loop EGR, was developed and optimized by using a commercial engine simulation program, GT-POWER. Some variables were selected to control dual loop EGR system such as VGT (Variable Geometry Turbocharger)performance, especially turbo speed, flap valve opening diameter at the exhaust tail pipe, and EGR valve opening diameter. Applying the dual loop EGR system in the light-duty diesel engine might cause some problems, such as decrease of engine performance and increase of brake specific fuel consumption (BSFC). So proper EGR rate (or mass flow) control would be needed because there are trade-offs of two types of the EGR (HPL and LPL) features. In this study, a diesel engine under dual loop EGR system was optimized by using design of experiment (DoE). Some dominant variables were determined which had effects on torque, BSFC, NOx, and EGR rate. As a result, optimization was performed to compensate the torque and BSFC by controlling start of injection (SOI), injection mass and EGR valves, etc.

• 에너지공학
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• 제10권4호
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• pp.318-326
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• 2001

중저온 배열회수를 통해 열설비의 열효율을 향상시키기 위하여 1 MW급 유기랭킨사이클시스템을 설계, 개발하였다. 포항제철소에 있는 두 대의 100 MW급 기력발전소에서 발생하는 175$^{\circ}C$의 배가스를 산업체에서 발생하는 대표적인 중저온배열원으로 선정하고, 환경오염을 최소화할 수 있는 신냉매인 HCFC-123을 시스템의 작동유체로 선정하였다. 유기냉킨사이클시스템의 시험운전을 통하여 유기랭킨사이클시스템이 산업체의 중저온배열을 회수하는데 유용함을 확인하였다. 열수의 가열, 터빈기동 및 전기투입방법 등의 운전방법을 최적화하였다. 그러나 HCFC-123 공급펌프의 능력부족으로 작동유체의 공급이 부족하여 정격출력보다 낮은 670kW의 전력을 생산할 수 있었다. HCFC-123의 공급유량을 증가시키기 위하여 파이프의 압력손실저하 및 펌프의 성능 향상을 위한 펌프교체 등이 고려되어야 함을 알 수 있었다.