THE EFFECT OF SPRAY ON COMBUSTION AND EMISSION IN DIRECT-INJECTION SPARK-IGNITION ENGINES

( Kyoungdoug Min ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

In the light of energy and environmental concerns, the CO₂ regulation for light-duty vehicles has become stricter than ever. Direct-injection spark-ignition (DISI) engine with a turbocharger is regarded as a major technology to improve the thermal efficiency and to lower the specific fuel consumption. However, the direct injection of gasoline leads the inhomogeneous air-fuel mixture in the cylinder and the fuel film deposition on the walls. As a result, the particulate matter (PM) emission is deteriorated compared to conventional port fuel injection engines. European Union enforced the emission regulation on the particulate number (PN) of DISI engine powered vehicles as 6×10¹¹/km from September 2017. To satisfy the stringent regulation without an after-treatment system, an in-depth understanding of the spray and combustion fundamentals, as well as a substantial optimization effort for the engine operating strategy, are required. The PM emission arises from the local fuel-rich mixture around the fuel film in DISI engines so that the spray injection plays the key role in the PM reduction. In this presentation, both experimental and numerical investigation on the effect of spray injection in a DISI engine will be covered. First, the potential of injection strategy on the PN emission level will be discussed based on the PM measurement in both metal and optical-accessible single-cylinder research engine. Then, the combustion and soot emission modeling and their application to CFD simulation will be presented to propose an efficient and reliable tool for the optimization of engine system. The rig-experiment enables the fundamental understanding of spray behavior and provides the valuable reference data for the model validation. This talk also discusses the spray evolution including penetration length, spray cone angle, and sauter mean diameter under various injection conditions. Finally, the measurement and modeling work on the spray-wall impingement and fuel film formation will be presented.

Effects of a split injection in a spray-guided direct-injection spark ignition engine under lean stratified operation

Oh, Heechang,Bae, Choongsik SAGE Publications 2014 Proceedings of the Institution of Mechanical Engin Vol.228 No.10

<P>The effects of a split injection were investigated in a spray-guided direct-injection spark ignition engine under lean stratified operation. In-cylinder pressure analysis, exhaust emissions measurement and visualization of the spray and combustion were applied. From the results using a single-injection strategy, stratified combustion showed advanced and rapid combustion characteristics. However, the low work conversion efficiency and the high nitrogen oxide emissions were obstacles to stratified combustion. Furthermore, the smoke emissions were high as a result of the dominant mixing-controlled combustion. A dual-injection strategy was applied to control the level of stratified combustion by modifying the dwell time and the split ratio. With a split injection, the nitrogen oxide emissions and the smoke emissions were reduced because of the moderated combustion speed and the enhanced local homogeneity. The liquid phase of the stratified mixture and the luminous sooting flame were reduced significantly as well. However, a low combustion efficiency and a low indicated mean effective pressure resulted owing to the over-mixing effect when the portion of lean premixed combustion was increased. Via moderately controlled stratified combustion, a split injection could be an effective way to reduce the nitrogen oxide emissions and the smoke emissions with a reasonable indicated mean effective pressure and a reasonable combustion efficiency.</P>

가솔린 및 LPG 연료를 사용하는 직접분사식 불꽃점화엔진에서 배출되는 극미세입자 배출 특성에 관한 연구

이석환(Seokhwan Lee),오승묵(Seungmook Oh),김홍석(Hongseok Kim),조준호(Junho Cho),차경옥(Kyoungok Cha) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5

In this study, the numbers, sizes of particles from a single cylinder direct injection spark-ignition (DISI) engine fuelled with gasoline and LPG are examined over a wide range of engine operating conditions. Tests are conducted with various engine loads (2~10bar of IMEP) and fuel injection pressures (60, 90, and 120 bar) at the engine speed of 1,500 rpm. Particles are sampled directly from the exhaust pipe using rotating disk thermodiluter. The size distributions are measured using a scanning mobility particle sizer (SMPS) and the particle number concentrations are measured using a condensation particle counter (CPC). The total particle number concentration for LPG was lower by a factor of 100 compared to the results of gasoline emission due to the good vaporization characteristic of LPG. Test result presents that LPG for direct injection spark ignition engine help the particle emission level to reduce.

직접분사식 암모니아 전소 엔진에서 점화 시기와 공기과잉률의 변경에 따른 연소 및 배기, 효율 특성 비교

장용훈,박철웅,김용래,최영,민찬기,이승우,백홍길,이정우 한국가스학회 2023 한국가스학회지 Vol.27 No.3

Due to the development of the industrial revolution, regulations on exhaust emissions have been continuously strengthened to reduce the rapidly increasing greenhouse gas emissions. The use of environmentally friendly fuels is essential to meet these regulations. Hydrogen has been attracting attention as a future environmentally friendly fuel, but due to its material properties, it faces significant challenges in handling and storage. As an alternative, ammonia has been proposed. Ammonia can be easily liquefied at room temperature compared to hydrogen and has a high energy density. In order to examine the applicability of ammonia as an engine fuel, experiments were conducted to investigate the effects of changes in combustion control parameters in a direct injection ammonia combustion engine. The experiments were conducted by varying two variables: spark timing and excessive air ratio. Observations were made on combustion stability and the trends of exhaust emissions such as nitrogen oxides and unburned ammonia under the conditions of an engine speed of 1,500 rpm and medium to high loads (brake torque of 200 Nm). By optimizing the combustion control parameters, conditions for stable combustion even when using ammonia as the sole fuel were identified, and plans are underway to apply strategies for future expansion of the operating range.

과급된 직접분사식 가솔린 엔진에서의 과도응답 특성 및 경량 TiAl 터빈 휠의 효과 분석

정진영(Jinyoung Jung),박찬수(Chansoo Park),배충식(Choongsik Bae) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12

다운사이징 엔진은 대 배기량 자연흡기엔진 대비 연비가 우수하지만 가속운전조건에서 응답성이 떨어져 이를 향상시키려는 많은 연구가 진행 중이다. 본 연구에서는 다운사이징 엔진을 대상으로 기존 Inconel 재질의 터빈 휠과 TiAl 재질의 경량 터빈 휠의 응답성을 과도응답조건에서 비교하였다. TiAl 터빈 휠은 회전관성이 Inconel 대비 작아 과급에 필요한 터빈 회전속도에 도달하는 시간이 상대적으로 짧아 과급 압력이 빠르게 증가하는 등 과도응답조건에서의 응답성이 개선되었다. In this study, performance tests were conducted under transient operation conditions in a turbocharged gasoline direct injection engine. In order to improve transient response, which is one of drawbacks of downsized engines, TiAl turbine wheel was evaluated compared with conventional Inconel turbine wheel. The inertia of TiAl turbine wheel is lower than that of Inconel one. Therefore, transient response was improved with TiAl turbine wheel because of that turbocharger speed of TiAl turbocharger was increased faster compared to Inconel turbocharger.

직접분사식 가솔린엔진용 고압 스월분무의 액막두께 측정 및 해석

문석수 ( Seok Su Moon ),오희창 ( Hee Chang Oh ),배충식 ( Choong Sik Bae ),( Essam Abo Serie ) 한국분무공학회 2007 한국액체미립화학회지 Vol.12 No.4

연료 변화에 따른 고압 스월 인젝터의 연료분무 특성

李珉湖,李焌瑞,車京玉 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-

In comparison with gasoline engine, LPG direct injection engine can have advantage in emission and fuel efficiency, and solve the problems which conventional LPG engine has, like power decrease and back fire etc. So, Direct injection engine technology is applied to LPG engine, it can show the solution of ULEV emission regulation. In this paper, the in-cylinder spray characteristics of LPG fuel has been studied in the CVC as a preliminary research for the development of low emission and high fuel efficiency of LPG engine in near future. During the direct injection of LPG fuel into the inside of CVC, both droplet development and vaporization characteristics according to the injection condition have been photographed by the high speed shadow graph and schlieren methods. The results are compared with the case of gasoline fuel.

메탄올-가솔린 혼합연료를 사용한 DISI엔진에서 연료의 혼합비와 2단분사가 엔진 내부유동 및 연소특성에 미치는 영향

배진우(Jin-Woo Bae),서주형(Ju-Hyeong Seo),이재성(Jae-Sung Lee),김호영(Ho-Young Kim) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.43

Numerical studies were conducted to investigate the internal flow field and combustion characteristics of DISI engine with the fuel of low fraction methanol, M0 and M31, in gasoline and two stage injection at 4000rpm WOT (Wide Open Throttle). Mass flow of the injected fuel to cylinder was corresponded air-fuel ratio of each fuel for complete combustion. This study presents the CFD modeling using S/W STAR-CD v3.26. When M31 fuel was used, uniformity, equivalence ratio mean pressure and temperature in cylinder increase. When two stage injection was used, there was no significant change in uniformity and equivalence ratio. But mean pressure and temperature in cylinder increase. When M31 fuel and one stage injection was used, the engine emission of carbon monoxide (CO) and nitrogen oxides (NO) increased about 36%, 12% comparing with benchmarking case in cylinder prior to TWC (Three Way Catalytic converter). and also, when two stage injection was used, CO and nitrogen oxides NO increased.

Impact of Ethanol in Ethanol Blended Gasoline on the Spray Characteristics of Piezo Actuated Outward-Opening Injector

Hua Wang,Heechang Oh,Jungseo Park,Choongsik Bae 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4

As ethanol fuel is a very attractive alternative fuel for spark ignition engines, it does make sense to take a closer look into direct injection spark ignition engine with ethanol fuel. In addition, the piezo actuated outward-opening injector has been demonstrated to have high potential for fuel consumption reduction. In this study, the spray characteristics of piezo actuated outward-opening injector was investigated while applying ethanol blended gasoline with different ethanol concentration (5%, 10%, 15% and 20% ethanol) as well as pure gasoline by means of injection quantity and injection rate measurement, planar Mie-scattering and shadowgraph techniques. A comparative analysis of blended fuels and gasoline sprays regarding injection parameters and spray characteristics is presented. The experimental results show the impact of ethanol fuel on the injection quantity and injection rate. Besides, it has been proved that low concentration ethanol in blended fuel could enhance spray evaporation. The concentration of ethanol will be extended in the later studies.

직접분사식 가솔린 엔진용 경사노즐 스월분무의 형태 결정 인자

문석수(Seoksu Moon),박정서(Jeongseo Park),배충식(Choongsik Bae) 한국자동차공학회 2007 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-

The swirl spray for direct injection gasoline engines was controlled using the tapered nozzles to fulfill the requirement of various combustion systems and the control mechanism causing the spray alterations were investigated. This study focused on how the correlation between taper angle, inclined angle of tapered nozzle, and flow angle affects the swirl spray shape. The macroscopic spray images were captured and velocity and droplet size distribution of tapered nozzle swirl spray were measured to understand the spray alterations at different taper angles. The result showed that fuel did not pass some area of nozzle exit and U or V shape spray was generated when the taper angle was higher than 90o minus flow angle. The velocity and fuel distribution of swirl spray were more asymmetrical and the spray robustness was enhanced when the taper angle was increased. The opened swirl spray, U or V shape spray generated when the taper angle is more than 90o minus flow angle, showed the possibility for the application of spray-guided combustion system as a result of enhanced spray momentum and reduced static air pressure drop inside the spray compared with the conventional swirl spray.