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대형 직접분사식 CNG 기관의 압축비 변화에 따른 기관출력 및 배기특성
남대우(Daewoo Nam),Trandangquoc,이종태(Jongtai Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
In this study, variable compression ratio system(VCRS) was applied on the heavy-duty CNG engine and the characteristics of power and emission was investigated according to the increasing of compression ratio. As compression ratio increasing, the increasing of thermal efficiency in direct injection is three times higher than that in port injection. The emission of HC and CO in direct injection is reduced about 14.2%, 17.7% but NOx is increased because of increasing temperature in cylinder.
Fe 연료첨가제를 적용한 HC 분사에 따른 저온영역에서 매연저감장치의 온도 및 재생특성에 관한 연구
남대우(Daewoo Nam),정건우(Gunwoo Jeong),성창율(Changryul Sung),강정호(Jeongho kang),정용현(Yonghyun Jeong),유영환(Younghwan You) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
In order to reduce the regeneration temperature of PM, Fe based fuel-additive is used in diesel fuel. And HC is injected in front of DOC as method to regenerate PM continuously in low temperature region of exhaust gas. As the result, in case of using fuel-additive, it is shown that the regeneration temperature of PM is lowered about 350℃ in comparison with normal regeneration temperature of PM. And the reduction effect of PM is larger than that in case of non-using fuel-additive. When HC is injected in front of DOC for continuous regeneration of PM, the inlet temperature range of DOC to oxidize HC is set up, which has effect on the range, duration of HC injection. Also the range of HC injection is affected according to regeneration temperature, THC emission.
암모니아 수용액(Urea) 분사 맵 구성을 위한 SCR 촉매특성 및 NOx 저감효과에 관한 연구
남대우(Daewoo Nam),강정호(Jeongho Kang),정건우(Gunwoo Jeong),김용태(Youngtae Kim),김태민(Taemin Kim),이해수(Haesoo Lee),김상훈(Changhee Kim),김창희(NaeHyun Lee) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
In order to form the basic map for the urea mass flow rate in Urea-SCR system, DOC/DPF and SCR was installed, then injection test was performed at various engine conditions. First of all, pre-map was comprised from the result of the space velocity and the NO₂/NOx ratio. As the result of experiment, it is shown that the NO₂/NOx ratio and the active region of SCR catalyst according to exhaust temperature have largely effect on forming the map of urea mass flow rate. And, in the case of increasing NH3/NOx ratio, NOx conversion is improved, but the NH₃ slip occurs according to increasing NH₃/NOx ratio, which is the factor to limit the region of the urea mass flow rate as well. Then, in case to inject the urea following the map, NOx is decreased about 65%. Although different aspects are shown due to many effect like high temperature, space velocity, NO2/NOx ratio, it is expected to satisfy emission standard EURO-V through the optimization of urea mass flow rate.
남대우(Daewoo Nam),Tran dang quoc,이종태(Jongtai Lee) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
EGR is applied to improve combustion stability in the heavy-duty direct injection CNG engine and port injection is used to compare EGR effect at the same condition, when EGR, two different ways are used. First, the throttle is fixed regardless of various EGR rate. So, when EGR rate increase, air mass flow is decreased by high temperature of exhaust gas. As a result, the engine performance is lowered because supply heat is reduced. Also, brake thermal efficiency is decreased for bsfc increased by high temperature of exhaust gas. Second, by using throttle, constantly air mass enters into the cylinder with various EGR rate. So, supply heat can be keep constantly and the mass of mixture gas with exhaust gas is increased. Therefore, pressure is more higher than that of non EGR in compression stroke and the engine performance is improved.
Off-road 차량용 디젤엔진의 NOx 저감을 위한 EGR 시스템 적용에 관한 연구
강정호(Jeongho Kang),남대우(Daewoo-Nam),정건우(Gunwoo Jeong),조규백(Kyubak Cho),장용수(Youngsoo Jang),김문형(Munhyung Kim),박상호(Sangho Park) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
In order to decrease NOx emission, the EGR system was applied on the off-road vehicle diesel engine. First of all, the primary map of EGR rate was formed by testing EGR in various engine driving conditions, and the engine performance and the NOx reduction was investigated. As the results of experiments, in the case of applying HPL EGR system on diesel engine used WGT, it is shown that the operating region of EGR is effective in low or middle load due to changing the differential pressure between turbocharger inlet and intake manifold. Increased EGR rate, NOx emission decrease according to increasing EGR rate, but THC shows the increasing tendency because of the increased fuel mass to compensate for the deteriorated power by EGR. Also, the temperature in intake and EGR system is raised highly by increasing the recirculated exhaust gas. From above results, the operating region of EGR is limited. However, NOx emission entirely decrease about 20~40% by applying EGR. So, if using the appropiate EGR rate for various engine driving condition, it is expected that NOx reduction is improved more and more.