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EGR cooler Fouling이 냉각 성능에 미치는 영향에 관한 연구
남연우(Younwoo Nam),오광철(Kwangchul Oh),김덕진(Dukjin Kim),김종훈(Jonghun Kim),이천환(Chunhwan Lee),이춘범(Chunbeom Lee) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
Understanding the exhaust gas recirculation (EGR) cooler fouling in diesel engine is important factor in the durability characteristic of the EGR system. We develope the test rig and PM feeder using carbon black to examine the effect of fouling on EGR cooler devices those were consisted of flat and spiral type tube. The EGR cooler fouling process is a complex interaction involving heat exchanger shape, boundary condition, constitutes, chemistry and operating mode. As the soot deposited to EGR cooler, these formed a thin deposit layer that was less heat exchange than the fresh status of tube enclosing the exhaust gas, resulting in lower heat exchange effectiveness in both type coolers. But these deposits caused different results in pressure drop, it is increased in flat type, but decreased in spiral type of EGR cooler. A cause was estimated from a change of the flow structure and a decrease of contac area as the EGR cooler fouling.
DPF 성능 평가를 위한 Dump Combustor의 활용
남연우(Youn Woo Nam),이원남(Wonnam Lee),오광철(Kwang Chul Oh),이춘범(Chun Beom Lee) 한국연소학회 2007 KOSCOSYMPOSIUM논문집 Vol.- No.-
The number of vehicles employing diesel engines is rapidly rising. Accompanying this trend, application of an after-treatment system is strictly required as a result of reinforced exhaust regulations. The Diesel Particulate Filter (DPF) system is considered as the most efficient method to reduce particulate matter (PM), but the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas compostion and flow rate of exhaust gas are important parameters in DPF evaluation, especially regeneration process. Engine dynamometer and degment tester are generally used in DPF evaluation so far. But these test method couldn't reveal the effect of various parameters on real DPF, such as O2 concentration, amount of soot and exhaust gas temperature. This research has studied the possibility using dump combustor that used to take an approach lean premixed combustion in gas turbine for a DPF power and optimized. It is possible that utilize the system as DOC (Diesel Oxidation Catalyst) and SCR(Selective Catalytic Reduction) assessments test as well as DPF evaluation
Modulated LII 신호와 이색법을 이용한 매연입자 온도 계측
남연우(Youn Woo Nam),이원남(Wonnam Lee) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
A new measurement technique based on a two-color pyrometry and modulated LⅡ signals to measure local soot particle temperatures has been proposed and examined experimentally. The theoretical review suggests that modulated LⅡ signals of soot particles is suitable for a two-color pyrometry as long as the temperature increase due to laser heating remains relatively small. The modulated LⅡ signals from ethylene and propylene diffusion flames were simultaneously measured at 550 and 750 ㎚ by a dual measurement system that consists of optical fibers, PMT and lock-in amps. The local soot particle temperatures of diffusion flames could be obtained using a two-color pyrometry and modulated LⅡ signal based new technique.
EGR Cooler 내부 형상에 따른 Fouling이 냉각 성능에 미치는 영향
남연우(Younwoo Nam),오광철(KwangChul Oh),이천환(Chunhwan Lee),이춘범(Chunbeom Lee),이원남(Wonnam Lee) 한국자동차공학회 2011 한국 자동차공학회논문집 Vol.19 No.1
Understanding the exhaust gas recirculation (EGR) cooler fouling in diesel engine is important factor in the durability characteristic of a EGR system. We develope a test rig and PM feeder using carbon black to examine the effect of fouling on EGR cooler devices those were consisted of flat and shell & tube type. The EGR cooler fouling process is a complex interaction involving heat exchanger shape, boundary condition, constitutes, chemistry and operating mode. As the soot deposited to EGR cooler, these formed a thin deposit layer that was less heat exchange than the fresh status of tube enclosing the exhaust gas, resulting in lower heat exchange effectiveness in both type coolers. But these deposits caused different results in pressure drop, it is increased in flat type, but decreased in Shell & tube type of EGR cooler. A cause was estimated from a change of the flow structure and a decrease of contact area as the EGR cooler fouling.
내부로 공급되는 공기 유량에 따른 에틸렌 확산화염의 매연 방출 현상
남연우(Younwoo Nam),문두성(Dusung Moon),이원남(Wonnam Lee) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.41
The characteristics of soot formation with air addition have been studied experimentally using a concentric co-flow diffusion burner, which provides the stratified air mixture through an inner nozzle. Integrated soot volume fraction, temperature and scattering images of diffusion flames were measured using a laser light extinction method, two-color pyrometry and 2-D laser light scattering technique, respectively. An ethylene diffusion flame started to emit soot with a small amount of air flow through an inner nozzle, which could be explained with the enhanced soot formation process due to the oxygenated species assisted pyrolysis. The increase of air flow rate up to 250 sccm transformed a soot emitting flame into a non-emitting flame without inner flame. Further increase of air flow rate created an inner flame and changed the flame into a soot emitting flame. When air flow rate was decreased again, the flame was changed back to a emitting flame; however, the presence of an inner flame altered the soot formation and oxidation characteristics of the flame and enhanced the soot formation process. The oxygenated species assisted pyrolysis, the radiation heat loss and the temperature effect of inner flames would determine the characteristics of soot production/oxidation of an ethylene diffusion flame with air flow inside.
후처리장치 성능 평가를 위한 Dump Combustor의 활용
남연우(Youn Woo Nam),이원남(Wonnam Lee),오광철(Kwang Chul Oh),이춘범(Chun Beom Lee) 한국연소학회 2007 한국연소학회지 Vol.12 No.3
Employing an after-treatment system has almost become a mandatory requirement for Diesel vehicles, which results from a reinforced exhaust regulations as the number of vehicles powered by a Diesel engine increases. The Diesel Particulate Filter (DPF) system is considered as one of the most efficient method to reduce particulate matter (PM); however, the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas composition and flow rate of exhaust gas are important parameters in DPF evaluation processes, especially during a regeneration process. Engine dynamometer and segment tester are generally used in DPF evaluation so far. These test methods, however, could not completely evaluate the effect of various parameters on real DPF, such as oxygen concentration, amount of soot and exhaust gas temperatures. The evaluation of DPF systems using a dump combustor has been verified experimentally and this dump combustor system is likely to be appropriate for the DOC (Diesel Oxidation Catalyst) and SCR (Selective Catalytic Reduction) assessments test, too.
공모형 부동산펀드의 수익률에 영향을 미치는 요인에 관한 연구 – 대출형과 임대형을 중심으로
남연우(yeon woo nam),성주한(joo-han sung),고석찬(suk-chan ko) 한국주택학회 2016 주택연구 Vol.24 No.4
본 연구는 공모부동산펀드 수익률 영향요인의 펀드 종류별 차이에 관한 연구를 위해 공모부동산펀드 자료를 활용하여 금융위기 전후의 거시경제 변수가 공모부동산펀드 수 익률에 펀드 종류별 어떠한 영향요인과 영향력의 변화가 있는지를 분석하였다 금융위기 이전에는 대출형 부동산펀드 모형은 자체변수 다음으로 산업생산지수 종합 주가지수 순으로 영향력이 있고 영향의 방향이 각각 양 의 방향 음 의 방향으로 나 타나는 것으로 관찰되었다 반면 임대형 부동산펀드 모형은 자체변수 다음으로 종합주 가지수 환율 순으로 영향력을 미쳤고 영향의 방향이 각각 양 음 인 바 경기 선행 지표로 인정되는 종합주가지수의 상승이 임대형 부동산펀드의 수익률에도 긍정적인 영 향을 미치며 영향력도 컸음을 의미하며 환율은 금융위기 이후까지 지속적으로 임대형 부동산펀드에 음 의 영향을 미치고 있어 대미환율이 하락하는 경우 원화 강세 외환이 국내 시장으로 유입되며 유입된 풍부한 유동성은 임대형 부동산펀드의 수익성을 상승 시키고 있음을 의미한다 금융위기 이후 대출형 부동산펀드 모형은 전반적인 거시경제변수의 영향력이 감소한 가운데 회사채의 영향력이 음 의 방향으로 대폭 증가하였다 반면 임대형 부동산펀드 모형은 자체변수의 영향력 증대와 자체 변수 다음으로 환율 산업생산지수 순의 영향의 정도가 관찰되었고 영향의 방향은 모두 음 인 것으로 나타났다 이러한 본 연구의 분석결과는 거시경제 환경변화에 공모부동산펀드의 수익률이 상당 한 영향을 받을 뿐만 아니라 펀드의 유형별로 상이한 결과를 보이고 있음을 나타내므로 향후 부동산펀드의 운용 시 이러한 점을 고려할 필요가 있음을 시사한다