LPG/바이오디젤 혼합연료를 사용하는 직접분사식 디젤엔진의 성능 및 배기특성에 관한 연구

이석환(Seok Hwan Lee),오승묵(Seung Mook Oh),최영(Young Choi),강건용(Kern Yong Kang) 한국가스학회 2010 한국가스학회지 Vol.14 No.1

본 연구에서는 LPG/바이오디젤 혼합연료의 직접분사식 디젤엔진 적용성에 관한 실험을 수행하였다. 특히, 혼합연료를 엔진에 적용하는 경우 엔진성능, 배출가스 (미연탄화수소, 일산화탄소, 질소산화물, 이산화탄소), 연소안정성에 대한 실험을 1,500 rpm의 엔진회전수 조건에서 수행하였다. 바이오디젤은 질량대비 20-60% 범위로 LPG에 혼합하였다. 바이오디젤을 40% 이상 혼합하는 경우 엔진은 모든 부하영역에서 매우 안정적으로 연소되었다. 바이오디젤의 혼합율이 증가할수록 혼합연료의 세탄가가 향상되어 연소시작 시점이 진각되었다. 혼합연료를 사용하면 저부하에서는 과혼합에 의한 부분연소로 인하여 THC와 CO의 배출량이 급증하였으며, NOx의 경우 저부하에서는 배출량이 디젤연료에 비해서 낮았으며 고부하에서는 더 많이 배출되었다. In this study, we experimentally investigated a compression ignition engine operated with Bio-diesel blended LPG fuel. In particular, the performance, emissions characteristics (including total hydrocarbon, carbon monoxide, nitrogen oxides, and carbon dioxides emissions), and combustion stability of a CI engine fueled with Bio-diesel blended LPG fuel were examined at 1500 rpm. The percentage of Bio-diesel in the fuel blend ranged from 20-60%. The results showed that stable engine operation was possible for a wide range of engine loads up to 40% Bio-diesel by mass. When the Bio-diesel content was increased, leading to a decrease in the lower heating value of the blended fuel, the cetane value increased, resulting in a advanced start of heat release. Exhaust emission measurements showed that THC and CO emissions were increased when using the blended fuel at low engine speeds due to partial burn from over-mixing. NOx emission was emitted less at lower loads and more at higher loads.

LPLi 인젝터의 누설특성 및 내구평가에 관한 실험적 연구

최영 ( Young Choi ),김창업 ( Chang Up Kim ),오승묵 ( Seung Mook Oh ),강건용 ( Kem Yong Kang ) 한국분무공학회 2007 한국액체미립화학회지 Vol.12 No.4

연료의 종류에 따른 부분산화 반응 특성에 관한 연구

박철웅(Cheol Woong Park),최영(Young Choi),오승묵(Seung Mook Oh) 한국가스학회 2009 한국가스학회지 Vol.13 No.4

고유가 시대의 도래와 강화되는 배출가스 규제에 대응하기 위한 대책으로 대체에너지 엔진 및 수소연료전지와 같은 새로운 연소 및 동력 기술에 대한 관심이 증대되고 있으나, 이러한 기술의 이용은 수소제조 및 공급 기반시설 구축이 선결되어야 하며 많은 투자가 요구된다. 수소를 내연기관에 활용하는 기술은 연료의 저장과 공급, 낮은 에너지 밀도 및 연소제어 등의 어려움이 있다. 그러나 화석연료로부터 합성연료를 제조하기 위한 중간단계로 생성되는 개질가스의 이용은 내연기관으로의 실시간 수소 공급을 가능하게 하고, 소량의 수소가 혼합연료 형태로 사용됨에 따라 연소특성을 향상시킬 수 있다. 본 연구에서는 다양한 연료들의 개질 특성을 이해함과 동시에 연료 개질기의 적용가능성 여부를 판단하고자 하였다. 연료별 최대의 수소수율을 얻을 수 있는 조건에서의 열역학적 개질효율과 수소수율을 관찰하였으며, 연료와 산화제의 촉매상에서의 체류시간에 대한 영향 및 연료/산화제 비율에 변화 시 최대 수소 수율을 제시하였다. Hydrogen can extend the lean misfire limit to a large extent when it is mixed with conventional fuels for an internal combustion engine. This study is about fuel reforming to produce hydrogen enriched gas as a fuel for engine. Especially gasoline, which consists of numerous hydrocarbon fuels, considered as source of reformed gas. Various hydrocarbons, including commercial fuel were reformed and potentialities of reformed gas on vehicles were accessed. The reforming efficiency and hydrogen yield were observed. Maximum hydrogen yield were found with different gas hourly space velocity (GHSV) and O2/C ratio of reforming conditions.

압축착화 엔진에서 분사압이 저온연소에 미치는 영향

장재훈 ( Jae Hoon Jang ),이선엽 ( Sun Youp Lee ),이용규 ( Yong Gyu Lee ),오승묵 ( Seung Mook Oh ),이기형 ( Ki Hyung Lee ) 한국분무공학회 2013 한국액체미립화학회지 Vol.18 No.1

Diesel low temperature combustion (LTS) is the concept where fuel is burned at a low temperature oxidation regime so that NOx and particulate matters (PM) can simultaneously be reduced. There are two ways to realize low temperature com-bustion engines. One is to supply a large amount of EGR gas combined with advanced fuel injection timing. The other is to use a moderate level of EGR with fuel injection at near TDC which is generally called Modulated kinetics(MK) method. In this study, the effects of fuel injection pressure on performance and emissions of a single cylinder engine were evaluated using the latter approach. The engine test results show that MK operations were successfully achieved over a range of with 950 to 1050 bar in injection pressure with 16% O₂concentration , and NOx and PM were significantly suppressed at the same time. In addition, with an increase in fuel injection pressure, the levels of smoke, THC and CO were decreased while NOx emissions were increased. Moreover, as fuel injection timing retarded to TDC, more THC and CO emissions were generated, but smoke and Nox were decreased.

EGR 제어를 통한 디젤 및 바이오디젤의 저온연소 특성 비교

이용규 ( Yong Gyu Lee ),장재훈 ( Jae Hoon Jang ),이선엽 ( Sun Youp Lee ),오승묵 ( Seung Mook Oh ) 한국액체미립화학회 2011 한국액체미립화학회지 Vol.16 No.3

Due to the oxygen contents in biodiesel, application of the fuel to compression ignition engines has significant advantages in terms of lowering PM formation in the combustion chamber. In recent days, considerable studies have been performed to extend the low temperature combustion regime in diesel engines by applying biodiesel fuel. In this work, low temperature combustion characteristics of biodiesel blends in dilution controlled regime were investigated at a fixed engine operating condition in a single cylinder diesel engine, and the comparisons of engine performances and emission characteristics between biodiesel and conventional diesel fuel were carried out. Results show that low temperature combustion can be achieved at O2 concentration of around 7~8% for both biodiesel and diesel fuels. Especially, by use of biodiesel, noticeable reduction (maximum 50%) of smoke was observed at low and middle loads compared to conventional diesel fuel. In addition, THC(total hydrocarbon) and CO(Carbon monoxide) emissions decreased by substantial amounts for biodiesel fuel. Results also indicate that even though about 10% loss of engine power as well as 14% increase of fuel consumption rate was observed due to lower LHV(lower heating value) of biodiesel, thermal efficiencies for biodiesel fuel were slightly elevated because of power recovery phenomenon.

직접분사식 LPG엔진에서 연료분사압력이 연소/배기특성에 미치는 영향 연구

이석환 ( Seok Whan Lee ),조준호 ( Jun Ho Cho ),오승묵 ( Seung Mook Oh ) 한국분무공학회 2011 한국액체미립화학회지 Vol.16 No.1

High pressure LPG fuel spray with a conventional swirl injector was visualized and the impact of the injection pressure was also investigated using a DISI (direct injection spark ignition) LPG single cylinder engine. Engine performance and emission characteristics were evaluated over three different injection pressure and engine loads at an engine speed of 1500 rpm. The fuel spray pattern appeared to notably have longer penetration length and narrower spray angle than those of gasoline due to its lower angular momentum and rapid vaporization. Fuel injection pressure did not affect combustion behaviors but for high injection pressure and low load condition (Pinj=120 bar and 2 bar IMEP), which was expected weak flow field configuration and low pressure inside the cylinder. In terms of nano particle formation the positions of peak values in particle size distributions were not also changed regardless of the injection pressure, and its number densities were dramatically reduced compared to those of gasoline.

연소제어인자의 변화에 따른 직접분사식 초희박 LPG엔진의 연소특성 연구

박윤서(Yun Seo Park),박철웅(Cheol Woong Park),오승묵(Seung Mook Oh),김태영(Tae Young Kim),최영(Young Choi),이용규(Yong Gyu Lee) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.6

오늘날 전 세계의 자동차 회사들은 연비를 향상시키고 배기가스를 저감시키기 위해 다양한 기술을 개발하고 있다. 그 중 직접분사식 초희박 연소기술은 연료제어의 정확도를 향상시켜 연소 효율을 극대화하고 초희박 연소를 통해 연비를 향상 시킬 수 있는 차세대 기술로 평가받고 있다. 따라서 기존 가스엔진에 초희박 직접분사 기술을 적용한 초희박 LPG 직접분사 엔진을 개발하기 위해 2ℓ 급 MPI 엔진을 베이스 엔진으로 실린더 헤드를 재설계하였다. 재설계된 헤드는 초희박 연소를 구현하기 위해 인젝터와 점화플러그가 헤드 중앙에 장착되는 분무유도방식 연소시스템을 적용하였다. 연료 분사 압력별 연료 분사 시기와 점화 시기의 변경을 통해 연료 소비율과 연소 안정성을 측정하였으며 이를 통해 최적연료 분사시기와 점화시기를 선정하였다. Nowadays, automotive manufacturers have developed various technologies to improve fuel economy and reduce harmful emissions. The ultra-lean direct injection engine is a promising technology because it has the advantage of improving thermal efficiency through the deliberate control of fuel and ignition. This study aims to investigate the development of a spray-guided-type lean-burn LPG direct injection engine through the redesign of the combustion system. This engine uses a central-injection-type cylinder head in which the injector is installed adjacent to the spark plug. Fuel consumption and combustion stability were estimated depending on the ignition timing and injection timing at various air-fuel ratios. The optimal injection timing and ignition timing were based on the best fuel consumption and combustion stability.

직접 분사식 가솔린 인젝터의 내구 평가 시스템 개발

이준순 ( Jun Sun Lee ),김태영 ( Tae Young Kim ),김창업 ( Chang Up Kim ),오승묵 ( Seung Mook Oh ),최교남 ( Kyo Nam Choi ),이용규 ( Yong Gyu Lee ) 한국액체미립화학회 2014 한국액체미립화학회 학술강연회 논문집 Vol.2014 No.-

The performance and efficiency in gasoline engines have been improved by adopting direct fuel injection system, and the fuel injection pressure is demanded to keep increasing in order to improve the atomization of fuel and in-cylinder mixing characteristics. Recently, the fuel injection pressure increased up to 200 bar and more. Therefore, various evaluation systems are needed for development of high pressure fuel injector. One of them is durability evaluation system. In this study, a new system has been developed. This system can evaluate injectors at the similar engine operating conditions. This system is able to control fuel temperature from 35 to 80.... injection pressure up to 250 bar, and operate injector at the engine speed of 40,000rpm maximum. Moreover, this durability evaluation system is equipped with an emergency function, which can detect the unexpected increase in temperature and pressure and stop the system. High pressure injectors of GDI engine were evaluated with this system. Static flow rate, dynamic flow rate, and leakage of the injector were analyzed at the before and after of durability evaluation. As a result, it is possible to evaluate a high pressure injector of a direct injection engine with this system.

압축비 변화에 따른 초희박 직접분사식 LPG엔진의 연소특성 연구

조시현(See Hyeon Cho),윤준규(Jun Kyu Yoon),박철웅(Cheol Woong Park),오승묵(Seung Mook Oh) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.10

최근 자동차 제조사는 강화되는 배출가스 규제를 만족시키고 엔진 효율을 향상시키기 위해 다양한 기술을 연구하고 있다. 그 중 직접분사식 초희박 연소기술은 정밀한 연소제어를 통해 연소효율을 극대화 하고 연비를 향상시킬 수 있는 차세대 기술로 평가받고 있다. 기존 가스엔진에 초희박 직접분사기술을 적용하기 위해 기존의 MPI 엔진의 헤드를 재설계하였다. 기존 압축비10:1에서 12:1로 증가시킴으로써 이에 따른 압력선도, 열방출률, 연료소비율 등의 연소특성과 배출가스특성을 파악하였다. 압축비를 증가시킴에 따라 불안정한 연소상태로 인하여 연료소비율의 개선이 어려웠으나 탄화수소(THC)와 질소산화물(NOx)의 배출은 감소되었다. Automotive manufacturers have recently developed various technologies for improving fuel economy and satisfying enhanced emission regulations. The ultra-lean direct injection engine is a promising technology because it has the advantage of improving thermal efficiency through the deliberate control of ignition. A conventional LPG engine has been redesigned to an ultra-lean-burn LPG direct injection engine in order to adopt combustion system of ultra-lean-burn . This study is aimed at investigating the effect of a change in the compression ratio on the performance and emission characteristics of a lean-burn LPG engine . The fuel consumption, heat release rate, combustion pressure, and emission characteristics are estimated depending on changing the effect of compression ratio . When the compression ratio is increased, it is difficult to improve the fuel consumption owing to an unstable combustion state, but the total hydrocarbon and nitrogen oxide emissions are reduced.

연료분무 및 연소 1 : 바이오디젤 저온연소에서 질소화합물과 매연 동시저감을 위한 최적 흡기압과 흡기산소농도

장재훈 ( Jae Hoon Jang ),이선엽 ( Sun Youp Lee ),이기형 ( Ki Hyung Lee ),오승묵 ( Seung Mook Oh ) 한국액체미립화학회 2013 한국액체미립화학회 학술강연회 논문집 Vol.2013 No.-

One effective way to simultaneously reduce NOx and smoke emissions in a diesel compression-ignition engine is to operate the engine in low temperature combustion (LTC) regimes. Two strategies are commonly used to realize the LTC operation, dilution-controlled LTC and late-injection LTC. The present study applied the former approach. In the dilution controlled regime, LTC is achieved by supplying a substantial amount of EGR to the cylinder. The significant EGR gas increases the heat capacity of in-cylinder charge mixture while decreasing oxygen concentration of the charge, activating low temperature oxidation reaction and lowering NOx and smoke emissions. However, the use of high EGR levels deteriorates combustion efficiency and engine power output. Therefore, it is widely considered to use increased intake pressure as a way to resolve this issue. Effects of intake pressure and oxygen concentration levels were investigated with a single-cylinder engine. Biodiesel (BD100) required intake oxygen concentration reduction to 13% to achieve simultaneous reduction of smoke and NOx, while Diesel required oxygen reduction to 8%, as in Figure 1. When intake pressure increased, combustion efficiency was improved so that THC and CO emissions were decreased. A shift of the peak smoke location was also observed to lower O2 concentration while NOx levels were kept nearly zero. In addition, an elevation of intake pressure enhanced engine power output as well as indicated thermal efficiency in LTC regimes. All these results suggested that LTC operation range can be extended and emissions can be further reduced by adjusting intake pressure.