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사용 후 커먼레일 디젤엔진의 고장분석 및 재제조 기술을 적용한 성능 비교
남충우(Chungwoo Nam),이호길(Hokil Lee),김현준(Hyunjun Kim),김락민(Rakmin Kim),정도현,송현석(Hyunseok Song),하치상(Chisang Ha),강춘길(Chunkil Kang) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
In this paper, operating characteristics and history of old 2.5L Common Rail Direct Injection(CRDI) diesel engine were investigated. With this base research, possible failure mode causes and effects analysis were performed. General four causes of diesel engine failure are from coolant, engine oil, abrasion, and consumables, But mainly 95% of failure are caused by coolant and engine oil. Therefore, performance of used engine and remanufactured engine from used one was analyzed with maximum power, maximum torque, combustion efficiency, brake specific fuel consumption(BSFC) and thermal efficiency. Hyundai`s A-engine which is one of 2.5L diesel engines was experimented on engine dynamometer. In the experiment, exhaust gas and output torque were measured at whole torque range. As a result, maximum power and torque of remanufactured engine were improved 23.65% at 3800rpm and 5.23% at 2000rpm each compared with used engine. Also, combustion efficiency, BSFC, and thermal efficiency were improved. By utilizing engine failure mode analysis, it is possible to establish more organized remanufacturing techniques and process, so resources could be used in an effective way.
2.2L 직분사 디젤 엔진에서 흡장형 NOx 촉매 재생 방법 비교
남충우(Chungwoo Nam),한만배(Manbae Han) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
In this study we investigated the regeneration methods for the lean NOx trap(LNT) catalyst in a 2.2L direct injection diesel engine. The regeneration methods were 1) in-cylinder post fuel injection and 2) external fuel injection strategy. The in-cylinder post fuel injection method uses in-cylinder injectors with the addition of the post fuel injection to supply enough reductants such as THC and CO. The external fuel injection method was enabled by installing a fuel injector with a wide spray angle before the LNT catalyst. Through the engine experiment, the NOx conversion efficiency, the amount of reductant exhaust gases, fuel consumption, and temperature behavior in the LNT catalyst were evaluated and compared for the two regeneration methods.
0.8MPa급 CNG 인젝터 노즐의 가스 분사 특성에 관한 실험적 연구
남충우(Chungwoo Nam),이호길(Hokil Lee),김재광(Jaekwang Kim),김재경(Jaekyoung Kim),이준혁(Junhyuk Lee),전완재(Wanjae Jeon) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.6
With the worsening energy crisis and environment pollution, a higher-efficiency internal combustion engine with lower emissions is crucial for engine manufacturers. Gas fuels like natural gas and hydrogen are currently regarded as promising alternative fuels whose use can resolve both the aforementioned problems, and there industry and engine research centers are exerting much effort to make these gas fuels viable for use in engines. This work was motivated by the desire to gain further insights into the characteristics of the low-pressure gas jet. Experimental gas jet investigation was successfully conducted through the schlieren technique, using a solenoid-valve injector with a maximum injection pressure of 0.8 MPa(absolute pressure) driven by a standard injector driver. Its supply voltage is 12 V, and its opening time, 1.4 ms. The injection pressure has a significant effect on the jet penetration. Also, a higher injection pressure leads to longer jet tip penetration. A high injection pressure leads to a higher jet momentum and higher turbulence energy, which means that the fuel-air mixing rate can be increased by increasing the injection pressure. The research results will be used to support the authors’ ongoing low-pressure injection natural gas engine project.
MOC 장착에 따른 CNG-디젤 혼소엔진의 배출가스 영향
남충우(Chungwoo Nam),이호길(Hokil Lee),김성철(Sungchoel Kim),강정호(Jeongho Kang),박주창(Joochang Park),김태민(Taemin Kim),최수식(Susik Choi) 한국자동차공학회 2018 한국자동차공학회 학술대회 및 전시회 Vol.2018 No.11
Methane emission from natural gas engine is difficult to remove from typical three-way and diesel oxidation catalyst after combustion. Therefore, recently trends of aftertreatment with natural gas engines have add methane oxidation catalyst to meet the strengthen of emission regulation. This paper is on the methane emission characteristic of natural gas-diesel dual fuel engine, which are new paradigm fo diesel engine. In this study, the 6.7liters EURO-VI diesel engine was converted to implement the natural gas-diesel dual fuel engine. Also the MOC under development was add to installed meet the strengthened emission regulation. The test conditions compared the diesel operation and the CNG-diesel operation and analyzed the emission characteristics of DOC up stream, DOC down stream and AOC down stream under each condition. Also, MOC was installed in front of DOC to compared the characteristics of emissions that according to the MOC installation. As a result In the CNG-diesel dual fuel operation condition, PM, NOx, and CO2 were reduced compared to diesel operating condition, but CO and THC were increased. Also In the CNG-diesel dual fuel operation condition more than 99% of the THC emission was methane. Meanwhile Even though there has been about 76% of THC reduction due to MOC integration, it still were not meet EURO-6(WHSC) emission standards. Thus a strategy to improve performance and efficiency of MOC catalyst and CNG fuel management system control will be established.
남충우(Chungwoo Nam),이호길(Hokil Lee),문성준(Seongjoon Moon),김재광(Jaekwang Kim),김구호(Guho Kim),이강윤(Kangyoon Lee) 한국자동차공학회 2017 한국 자동차공학회논문집 Vol.25 No.5
The aim was to develop a new generation of electronic pressure regulator that can continuously vary the rail pressure in front of the injectors. The new pressure regulator can react on different pressure requirements in the CNG rail. The focus was on the functional optimization and size reduction. The proportional valve, which is a solenoid valve, is controlled by a PWM signal. Duty cycle 0 % means a closed valve, while 100 % means the proportional valve is fully open. The pressure regulation is divided into two stages. The first stage is mechanical regulation from a tank pressure of 0.2 to 26 MPa to a constant middle pressure of 2 MPa. The different type regulators was labeled as 1) A sample and 2) B sample. Through the bench experiment, the stroke characteristic of supply voltage, heat exchange effect on the low pressure side depending on cooling water capacity and cross-section area, the mass flow of different inlet pressure and rail pressure, and behavior in the regulator were evaluated and compared.
2.2L 직분사 디젤 엔진에서 LNT 촉매 재생을 위한 환원제 분사 방법 비교
남충우(Chungwoo Nam),한만배(Manbae Han) 한국자동차공학회 2015 한국 자동차공학회논문집 Vol.23 No.2
In this study we investigated the regeneration methods for the lean NOx trap (LNT) catalyst in a 2.2L direct injection diesel engine. The regeneration methods were 1) in-cylinder post fuel injection and 2) external fuel injection strategy. The in-cylinder post fuel injection method uses in-cylinder injectors with the addition of the post fuel injection to supply enough reductants such as CO, H₂, THC. The external fuel injection method was enabled by installing a fuel injector with a wide spray angle before the LNT catalyst. Through the engine experiment, the NO<SUB>x</SUB> conversion efficiency, the amount of reductant exhaust gases, fuel consumption, and temperature behavior in the LNT catalyst were evaluated and compared for the two regeneration methods.
GDI-CNG Bi-fuel 엔진에서 가솔린 인젝터 막힘에 따른 제어전략 수립
남충우(Chungwoo Nam),오세두(Sedoo Oh),박장훈(Janghun Park),이명윤(Myoungyoon Lee) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
온실가스 감축을 위한 배기 규제가 단계적으로 강화됨에 따라, 수소 및 전기차로 완전히 전환 이행되기 전까지, 천연가스가 내연 기관 친환경 대체 연료로 주목받고 있다. 본 논문에서는 1.4L T-GDI엔진에 CNG 연료시스템(레귤레이터, 인젝터, 연료레일 등)을 적용하여, 가솔린-CNG 겸용 시스템을 구축하여 실험을 진행하였다. 단일 연료 별로, 차량 주행 시 GDI 인젝터 노즐 팁 (끝단)의 온도를 각각 측정하였으며, CNG 단일 연료로만 운전했을 때, 가솔린 연료계 부품인 GDI 인젝터에 생기는 문제점을 도출하였다. 가솔린 단일 연료로 운전 시 GDI 인젝터 노즐팁의 평균 온도는 약 120℃로, 인젝터가 액상 연료를 분사할 때 냉각 효과가 발생하여, 인젝터 노즐 팁의 온도가 일정 수준 이상 올라가지 않는 것으로 보인다. 하지만, CNG 연료만을 사용하여 운전하였을 때, GDI 인젝터 노즐 팁 온도는 가솔린으로 운전했을 때보다 최대 53.6℃ 높았으며, 약 180℃까지 상승하는 영역을 확인하였다. 이로 인해, GDI 인젝터 내부의 니들 밸브 부위가 지속적인 열에 노출되어 녹아 내렸고, 고압 분사 홀(hole)과 기밀 유지가 되지 않아, 실린더 압력 저하 및 가솔린 연료계 고장을 야기함을 X-ray 촬영을 통해 알게 되었다. 나중에는 인젝터 홀 자체가 열 손상되어, 가솔린 운전으로 전환하였음에도 연소 안정성 저하 및 연료 분사 불량에 따라 엔진 부조가 발생한다. 따라서 기존 GDI 엔진에 CNG 연료시스템을 추가 장착할 경우, 냉간 시동 시, 오직 가솔린 연료로만 초기 시동하도록 알고리즘을 수정하였다. 고부하 영역에서는 발열을 냉각하기 위해 가솔린 연료를 분사하여, CNG 운전에 따른 GDI 인젝터 고착을 방지하는 제어 전략을 수립하였다. 향후 CNG-GDI 겸용 엔진을 제작할 때에는, 기존 가솔린 엔진 연료계 부품보다, 열 내구성이 더 높은 신규 부품 장착이 요구된다. As an emission standard being strict in phase to reduce Greenhouse Gas (GHG), Natural Gas referred as Compressed Natural Gas (CNG) or Liquified Natural Gas (LNG) is promoted as a green energy to alternate conventional fuels as gasoline and diesel, before all the vehicles turnover to full Zero emission technology such as Hydrogen or Battery Electric. In this thesis, we consider 1.4L Turbocharged Gasoline Direct Injection (T-GDI) engine with CNG fuel system including regulator, injector and fuel rail. A time series of temperature at a tip of injection nozzle was measured driven with gasoline and CNG, respectively. In the driving circumstance with CNG mono fuel, some of issues were detected at GDI injectors. Relatively, in the driving circumstance with gasoline mono fuel, the temperature was about 120℃ on average at a tip of injection nozzle. We determined it affects cooling to injectors during injecting gasoline as liquid, but when driving with CNG only, it goes up to about 180℃ and higher than 53.6℃ compared to the highest temperature at driving with gasoline. Therefore, a needle valve of GDI injector melted down due to consistent higher temperature. It resulted in loosing pressure inside the cylinder and failure of gasoline system as an injector hole being heat damaged, despite of switching fuel system to gasoline, eventually. Thus, in case retrofit gasoline engine with CNG fuel system, only gasoline fuel set to be injected at a cold start. At high load, gasoline also inject with CNG to cool down and prevent injectors getting clogged. When establishing further strategy, it is required to adopt a injector highly heat-resisting, instead of existing GDI injector.