• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.179-182
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• 2012

Effect of double post injections on diesel PCCI combustion with focus on HC emission was investigated in a single-cylinder direct-injection diesel engine. The ISFC, HC and CO emissions were reduced by single or double post injections. The application of double post injections could also improve the trade-off relationship between NOx and HC emissions under wide EGR rate range.

• 한국항공우주학회지
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• 제50권5호
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• pp.339-347
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• 2022

하이브리드 로켓의 후연소실(post chamber)은 액화된 연료의 추가적 연소를 유도하여 엔탈피 상승으로 이어지도록 한다. 후연소실이 있는 하이브리드 로켓에 파라핀 왁스를 연료로 사용하는 경우, 연소초기에만 비정상 연소 압력진동이 관찰된다. 본 연구는 비정상 연소 압력진동의 발생과 액적의 추가적 연소 사이의 상관관계를 확인하는 것을 목적으로 하고 있다. 이를 위해 후연소실 연소를 가시화하고 POD 기법을 활용한 이미지 분석을 수행하였다. 또한 모드 재구성을 통해 액적의 거동을 포함하고 있는 모드를 분리하여 비정상적인 연소압력의 진동과 액적의 연소 사이의 상관관계를 조사하였다. 일련의 실험에서는 후연소실로 유입되는 액화 연료량과 액적발생을 조절하여 비정상 연소압력 진동의 변화를 유도하였다. 실험결과에 의하면 파라핀 왁스의 연소 초기에만 관찰되는 비정상 연소압력 진동은 후연소실에서 발생하는 액적의 추가적인 연소가 그 발생원인임을 알 수 있다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.311-312
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• 2012

Homogeneous charge compression ignition combustion with multiple-injection strategy using dimethyl-ether was investigated in a single cylinder direct-injection compression-ignition engine. The combustion performance and exhaust emissions were tested by varying the post injection conditions. The experiments were carried out under low load and low speed conditions. By the late post injection near the top dead center, the combustion phase was retarded and lengthened, and the fuel conversion efficiencies improved without the drawbacks of exhaust emissions increment.

• 한국수소및신에너지학회논문집
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• 제28권1호
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• pp.30-39
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• 2017

Interests in fuel cell based power generation systems are on the steady rise owing to various advantages such as high efficiency, ultra low emission, and potential to achieve a very high efficiency by a synergistic combination with conventional heat engines. In this study, the performance of a hybrid system which combined a molten carbonate fuel cell (MCFC) and an indirectly fired micro gas turbine adopting carbon dioxide capture technologies was predicted. Commercialized 2.5 MW class MCFC system was used as the based system so that the result of this study could reflect practicality. Three types of ambient pressure hybrid systems were devised: one adopting post-combustion capture and two adopting oxy-combustion capture. One of the oxy-combustion based system is configured as a semi-closed type, while the other is an open cycle type. The post-combustion based system exhibited higher net power output and efficiency than the oxy-combustion based systems. However, the semi-closed system using oxy-combustion has the advantage of capturing almost all carbon dioxide.

• 한국자동차공학회논문집
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• 제22권1호
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• pp.193-201
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• 2014

A numerical study has been carried out to analyze the combustion characteristics in heavy duty diesel engine with post injection for reducing NO emission. For verification of numerical study results, calculated cylinder pressure was matched to experimental data. In this study, post injection timing and amount of post injection were modified as parameters, but the total amount of injection fuel was maintained. As the results, maximum cylinder pressure increases above minimum 2% by post injection and end of pressure curve is decreased rapidly. The more dwell time and amount of post injection fuel are, the more pressure drop occurs. And trade-off relation of NO and soot are appeared. In the results, NO was reduced without deterioration of cylinder pressure under condition of $10^{\circ}$ CA dwell time and main 60%, post 40% fuel portion.

• 한국추진공학회지
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• 제23권5호
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• pp.19-26
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• 2019

파라핀 연료는 일반적으로 상당량의 미연 액적들이 노즐로 배출되는 관계로 연소효율을 낮아 연소효율과 직결된 후연소실의 최적화는 중요한 성능인자로 대두되고 있다. 따라서 본 연구에서는 하이브리드 로켓용 후연소실 길이 및 직경 변화에 따른 연소 특성을 파악하기 위한 연소 시험을 수행하였다. 연소 시험 결과, 후연소실 길이가 증가할수록 특성속도효율이 상승함을 확인하였으며 이는 후연소실 길이가 증가할수록 연소가스의 잔류시간 증가와 연소실 압력에 기인되는 것으로 판단되었다. 반면, 후연소실 직경 변화에 따른 특성속도효율 및 압력의 차이는 길이 변화 대비 크지 않음을 확인하였다. 따라서 하이브리드 로켓 시스템의 연소효율에 영향을 미치는 후연소실의 기하학적 요인은 직경보다는 길이의 영향에 크게 지배되는 것으로 사료된다.

• 한국세라믹학회지
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• 제38권4호
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• pp.301-301
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• 2001

• 한국세라믹학회지
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• 제38권4호
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• pp.307-307
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• 2001

Combustion process with citrate was used to produce the LiMn$_2$O$_4$powder. Precursors are pre-ignited in open air followed by post-heating in the range from $600^{\circ}C$ to 80$0^{\circ}C$ for 4h. With varying the molar ratio (R) of ethylene glycol (EG) to citric acid (CA) from 0 to 4, the effect of EG content on powder characteristics is evaluated. Vacuum drying promote the auto-ignition at room temperature. With small addition of EG metal ion was selectively segregated with organic substances and undesired lithium evaporation occurred during post-heating. LiMn$_2$O$_4$phase which is produced by combustion reaction was decomposed back to Mn$_3$O$_4$because the reaction temperature was higher than 95$0^{\circ}C$. With increasing EG content, the homogeneity of LiMn$_2$O$_4$powder increased and specific surface area increased. And lithium evaporation during vacuum drying and/or ignition also increased.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.99-105
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• 2011

This paper described the effect of the multiple injections on the emission characteristics and combustion stability in a common rail diesel engine. In order to investigate the influence of multiple injections in a passenger car diesel engine, the injection strategy was varied with pilot injection, post injection and one main injection at various conditions. Based on the experimental results, the combustion and emissions characteristics were analyzed for the various injection strategies such as main, pilot-main, double-pilot-main, double- pilot-main-post injection strategy. It is revealed that the $NO_X$, HC and CO emissions are reduced by double pilot and post injection at medium load, however, soot emission is increased. Also, in the case of multiple injection, the combustion pressure is increased smoothly near the TDC and the coefficient of variation and fuel consumptions are decreased.

• 설비공학논문집
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• 제22권8호
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• pp.545-552
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• 2010

Research and development efforts to reduce $CO_2$ emission are in progress to cope with global warming. $CO_2$ emission from fossil fuel fired power plants is a major greenhouse gas source and the post-combustion $CO_2$ capture is considered as a short or medium term option to reduce $CO_2$ emissions. In this study, the application of the post-combustion $CO_2$ capture system, which is based on chemical absorption and stripping processes, to typical fossil fuel fired power plants was investigated. A coal fired plant and a natural gas fired combined cycle plant were selected. Performance of the MEA-based $CO_2$ capture system combined with power plants was analyzed and overall plant performance including the energy consumption of the $CO_2$ capture process was investigated.