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초희박 LPG 직접분사식 엔진에서 질소산화물 저감을 위한 배기재순환 적용성 평가
박철웅(Cheolwoong Park),조시현(Seehyeon Cho),김태영(Taeyoung Kim),조규백(Gyubaek Cho),이장희(Janghee Lee) 한국가스학회 2015 한국가스학회지 Vol.19 No.4
LPG가 수송용 연료로서 경쟁력을 유지하기 위해서는 지속적인 기술개발을 통해 휘발유와의 연비격차를 감소시키고 후처리시스템 등에 의한 가격 부담을 낮추어야 한다. 이에 본 연구에서는 안정적인 희박연소 구현을 통한 연비개선을 얻기 위해 실린더 중앙에 점화플러그와 연료분사기가 인접해 있고, 연료가 분사된 후 바로 점화가 이루어지도록 하는 분무유도방식의 LPG 직접분사엔진을 개발의 일환으로 연소제어인자의 변화에 따른 연소 특성을 분석하였다. 안정적인 연소를 위해 국부적으로 농후한 혼합기를 형성하는 성층희박연소의 특성상 일정 수준이상의 질소산화물이 배출되는 문제점을 갖고 있다. 질소산화물 저감을 위해 EGR을 적용한 결과 연료소비율과 THC의 배출은 약간 증가하지만 NOx배출은 약 15% 저감되었다. EGR 적용에 의한 연소속도의 감소는 초기 화염발달 시기에 집중되어 나타났으며 흡입공기의 희석효과에 의해 EGR율이 증가할수록 최대 열방출율 및 열방출율 증가 기울기가 감소하였다. In order to keep the competitiveness of LPG fuel for transportation fuel, the difference in fuel consumption with gasoline and cost for an aftertreatment system should be reduced with continuous development of technology for LPG engine. In the present study, spray-guided type direct injection combustion system, whose configuration is composed of direct injector in the vicinity of spark plug, was employed to realize stable lean combustion. A certain level of nitrogen oxides(NOx) emits due to a locally rich mixture regions in the stratified mixture. With the application of EGR system for the reduction of NOx, 15% of NOx reduction was achieved whereas fuel consumption and hydrocarbon emission increased. By the application of EGR, the combustion speed reduced especially appeared at initial flame development period and peak heat release rates and increasing rates for heat release rate decreased as EGR rate increased due to the dilution effect of intake air.
대형 천연가스 엔진에서 과급에 따른 희박연소 및 배기 특성
박철웅(Cheolwoong Park),원상연(Sangyeon Won),김창기(Changgi Kim),최영(Young Choi) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
Natural gas vehicles have demonstrated significantly lower exhaust emissions compared to their gasoline and diesel fueled vehicles. Also a possible approach for meeting future emission regulations with current natural gas engine designs is to blend hydrogen with CNG. HCNG allows lean burn and retarded spark timing and and high thermal efficiency. These can reduce emissions considerably without the use of exhaust after-treatment system. The volumetric efficiency is known as one of the most important factor which affects significantly engine performance, fuel economy and further emissions. Supercharging system was adopted to investigate the influence of boost pressure on operating range. In this study, the boosted HCNG engine showed high thermal efficiency and torque for the lean combustion condition and the effect of supercharging and compression ratio on engine characteristics.
LPG 액상분사식 인젝터의 후적 및 아이싱 특성에 관한 연구
박철웅(Cheolwoong Park),김창업(Changup Kim),최교남(Kyonam Choi),강건용(Kernyong Kang) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Since the liquid phase LPG injection (LPLI) system has an advantage of higher power and lower emission characteristics than the mixer type fuel supply system, many studies and applications have been conducted. However, the heat extraction, due to the evaporation of liquid fuel, causes not only a post-accumulation of fuel but also an icing phenomenon that is a frost of moisture in the air around the nozzle tip. Because both lead to a difficulty in the control of accurate air fuel ratio, it can result in poor engine performance and a large amount of harmful emissions. The experimental investigation was carried out on the bench test rig during this study. It was found that n-butane, that has a relatively high boiling point (- 0.5℃), was a main species of post-accumulation and also found that the post-accumulation problem was improved by the use of a large inner to outer bore ratio nozzle whose surface roughness is smooth. The icing phenomena were decreased when the temperature of an engine head was increased, although a large amount of icing deposit was observed in the case of 87℃.
하이브리드용 가솔린 엔진에서 최적 EGR적용에 따른 성능 및 배출가스 특성 분석
박철웅(Cheolwoong Park),최영(Young Choi),김창기(Changgi Kim) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
EGR(Exhaust gas recirculation) provides an important contribution in achieving the development targets of low fuel consumption and low exhaust emission levels on gasoline-hybrid engines while allowing stoichiometric fuelling to be retained for applications using the three-way catalysts. However, the occurrence of excessive cyclic variation with high EGR normally prevents substantial fuel economy improvements from being achieved in practice. Therefore, the optimum EGR rate in Gasoline-Hybrid engine should be carefully determined in order to achieve low fuel consumption and low exhaust emission. In this study, 2 liters gasoline engine with E-EGR system was used to investigate the effects of EGR with optimum EGR rate on fuel economy, combustion stability, engine performance and exhaust emissions. As the engine load becomes lower, the EGR rate is increased. The increase in engine load and reduction in engine speed make the fuel consumption better. The fuel consumption was improved by maximum 5.5% at low speed, high load operating condition.
후분사가 소형 직분식 디젤 엔진의 성능과 배기에 미치는 영향
박철웅(Cheolwoong Park),국상훈(Sanghoon Kook),배충식(Choongsik Bae) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Common rail injection system is a flexible equipment to control injection timing, pressure and multi-injection. Many studies and applications have reported the advantages of using common rail system to meet the strict emission regulation and to improve engine performance for diesel engine by this flexibility. The main objective of this study is to investigate the effect of after- fuel-injection strategies on engine performance and emissions. The study was carried out on a single cylinder optical direct injection diesel engine equipped with a high pressure common rail fuel injection system. The after-injection was found to be very effective in completing the oxidation process and reducing the particulate emissions even when small fuel quantity was injected.<br/>
HCNG 엔진의 터보차저 변경에 따른 전부하 출력 및 배출가스 특성 연구
박철웅(Cheolwoong Park),김창기(Changgi Kim),임기훈(Gihun Lim),이성원(Sungwon Lee),최영(Young Choi),이선엽(Sunyoup Lee) 한국가스학회 2013 한국가스학회지 Vol.17 No.5
천연가스에 수소를 첨가하는 수소-천연가스 혼합연료 (HCNG) 엔진 기술은 수소의 빠른 화염속도와 넓은 가연범위를 이용하여 출력 및 배기성능을 최적화하는 기술로서 희박연소 한계를 증가시킴으로써 열효율의 개선은 물론 유해배출물의 저감을 얻을 수 있다. 그러나 과급장치를 사용하는 희박연소 엔진의 경우 전부하 운전조건에서 희박연소 한계의 증가는 충분한 공기량을 공급할 수 있도록 과급용량의 증가가 선결되어야 구현될 수 있다. 본 연구에서는 HCNG 엔진 개발의 일환으로 과급시스템의 변경에 의한 엔진의 출력특성을 파악하고, 과급용량 증대의 적용가능성을 검토하고자 하였다. 터보차저가 과급압력의 증대 보다는 유량이 증가된 영역에서 효율이 높게 설계된 경우 농후한 혼합기 조건에서는 과급압력이 감소되더라도 제원상의 출력을 만족하며 효율적인 운전이 가능하였다. Hydrogen-natural gas blends(HCNG) engine is optimizing technology of performance and emission characteristics with use of hydrogen’s fast flame speed and wide flammability limit. As lean-burn limit is extended, the improvement in thermal efficiency and harmful emissions can be achieved. However, the extension of lean-burn limit under a wide open throttle operation point could be realized with the increase in boosting capacity in a lean-burn engine with turbo-charging system. In the present study, the power output characteristics of HCNG engine with turbo-charger change is assessed and feasibility of the increase in boosting capacity is evaluated. The turbo-charger design with high efficiency at higher flow rate rather than higher boosting pressure makes efficient operation possible at relatively rich mixture condition.