예혼합 압축 착화 가솔린 엔진에서 DME의 점화 촉진

염기태(Kitae Yeom),장진영(Jinyoung Jang),배충식(Choongsik Bae) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_1

Homogeneous charge compression ignition (HCCI) combustion is an attractive way to lower carbon dioxide (CO₂), nitrogen oxides (NOx) emission and to allow higher fuel conversion efficiency. However, HCCI engine has inherent problem of narrow operating range at high load due to high in-cylinder peak pressure and consequent noise. To overcome this problem, the control of combustion start and heat release rate is required. It is difficult to control the start of combustion because HCCI combustion phase is closely linked to chemical reaction during a compression stroke. The combination of variable valve timing (VVT) and gas fuel injection of high cetane number was chosen as the most promising strategy to control the HCCI combustion phase in this study. Regular gasoline was injected at intake port as main fuel, while small amount of di-methyl ether (DME) was also injected directly into the cylinder as an ignition promoter for the control of ignition timing. Different intake valve timings were tested for combustion phase control. Regular gasoline was tested for HCCI operation and emission characteristics with various engine conditions. This paper investigates the steady-state combustion characteristics of the HCCI engine with VVT, to find out its benefits in exhaust gas emissions. With HCCI operation, higher internal exhaust gas recirculation (EGR) rate and the longer combustion duration, reduced NOx emissions. However, hydrocarbon (HC) emission is relatively higher than that under sparkignition combustion.

가솔린과 LPG 예혼합 압축 착화 엔진의 노킹 특성

염기태(Kitae Yeom),배충식(Choongsik Bae) 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.3

The knock characteristics in an engine were investigated under homogeneous charge compression ignition (HCCI) operation. Liquefied petroleum gas (LPG)and gasoline were used as fuels and injected at the intake port using port fuel injection equipment. Di-methyl ether (DME) was used as an ignition promoter and was injected directly into the cylinder near compression top dead center (TDC). A commercial variable valve timing device was used to control the volumetric efficiency and the amount of internal residual gas. Different intake valve timingsand fuel injection amounts were tested to verify the knock characteristics of the HCCI engine. The ringing intensity (RI) was used to define the intensity of knock according to the operating conditions. The RI of the LPG HCCI engine was lower than that of the gasoline HCCI engine at every experimental condition. The indicated mean effective pressure (IMEP) dropped when the RI was over 0.5 MW/m2and the maximum combustion pressure was over 6.5 MPa. There was no significant relationship between RI and fuel type. The RI can be predicted by the crank angle degree (CAD) at 50 CA. Carbon monoxide (CO) and hydrocarbon (HC) emissions were minimized at high RI conditions. The shortest burn duration under low RI was effective in achieving low HC and CO emissions.

가솔린 예혼합 압축 착화 엔진의 농후 한계에서 연소와 노킹 특성

염기태(Kitae Yeom),장진영(Jinyoung Jang),배충식(Choongsik Bae) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.6

Variable valve timing is one of the attractive ways to control homogeneous charge compression ignition (HCCI) engine. Hot internal residual gas which can be controlled by variable valve timing (VVT) device, makes fuel evaporated easily, and ignition timing advanced. Regular gasoline was used as main fuel and di-methyl ether (DME) was used as ignition promoter in this research. HCCI engine operating range is limited by high combustion peak pressure and engine noise. High combustion pressure can damage the engine during operation. To avoid engine damage, the rich limits have to define using various methods. Peak combustion pressure, rate of cylinder pressure rise was considered to determine rich limit of engine operating range. Knock probability was correlated with the rate of cylinder pressure rise as well as the peak combustion pressure.

예혼합 압축 착화 엔진에서 노킹 예측 및 배기 배출물 저감

염기태(Kitae Yeom),배충식(Choongsik Bae) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The knock characteristic and estimation in an engine were investigated under homogeneous charge compression ignition (HCCI) operation. Liquefied petroleum gas (LPG) and gasoline were used as fuels and injected at the intake port using port fuel injection equipment. Di-methyl ether (DME) was used as an ignition promoter and was injected directly into the cylinder during the intake stroke. A commercial variable valve timing device was used to control the volumetric efficiency and the amount of internal residual gas. Different intake valve timings and fuel injection amounts were tested to verify the knock characteristics of the HCCI engine. The ringing intensity (RI) was used to define the intensity of knock according to the operating conditions. The RI of the LPG HCCI engine was lower than that of the gasoline HCCI engine at every experimental condition. The indicated mean effective pressure (IMEP) dropped when the RI was over 0.5 ㎿/㎡ and the maximum combustion pressure was over 6.5 ㎫. There was no significant relationship between RI and fuel type. The RI can be predicted by the crank angle degree (CAD) at 50 CA. Carbon monoxide (CO) and hydrocarbon (HC) emissions were minimized at high RI conditions. The shortest burn duration under low RI was effective in achieving low HC and CO emissions.

LPG - DME 압축착화 엔진에서 흡기 가변밸브 영향

염기태(Kitae Yeom),배충식(Choongsik Bae) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.2

The combustion and exhaust emissions characteristics of a liquefied petroleum gas-di-methyl ether compression ignition engine with a variable valve timing device were investigated under various liquefied petroleum gas injection timing conditions. Liquefied petroleum gas was used as the main fuel and was injected directly into the combustion chamber. Di-methyl ether was used as an ignition promoter and was injected into the intake port. Different liquefied petroleum gas injection timings were tested to verify the effects of the mixture homogeneity on the combustion and exhaust emission characteristics of the liquefied petroleum gas-di-methyl ether compression ignition engine. The average charge temperature was calculated to analyze the emission formation. The ringing intensity was used for analysis of knock characteristics. The combustion and exhaust emission characteristics differed significantly depending on the liquefied petroleum gas injection and intake valve open timings. The CO emission increased as the intake valve open and liquefied petroleum gas injection timings were retarded. However, the particulate matter emission decreased and the nitrogen oxide emission increased as the intake valve open timing was retarded in the diffusion combustion regime. Finally, the combustion efficiency decreased as the intake valve open and liquefied petroleum gas injection timings were retarded.

Top-Feed Type 인젝터의 액상분사 LPG연료 분사장치 적용

염기태(Kitae Yeom),박정서(Jungseo Park),배충식(Choongsik Bae),박정남(Jeongnam Park),김성근(Sungkun Kim) 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.6

The injection and spray characteristics of top-feed type injector was investigated under liquid phase injection fueled with liquefied petroleum gas (LPG). Different pressures and temperatures of fuel injection system were tested to identify the injection characteristics after hot soaking. MIE-scattering technique was used for verification of successful liquid phase injection after hot soaking. In case of bottom-feed type injector, the injection was accomplished at every experimental condition. In case of top-feed type injector, when the pressure of LPG was over 1.2 ㎫, the injection was not executed. However, under the pressure were 1.2 ㎫, the liquid phase injection after hot soaking was accomplished. The engine with top-feed type fuel injection equipment was restarted successfully after hot soaking.

병렬형 디젤 하이브리드 전기 자동차 최적화

염기태(Kitae Yeom),양재식(Jaesik Yang),배충식(Choongsik Bae),김현옥(Hyunok Kim) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.19 No.6

This research presents a simulation for the fuel economy of parallel diesel hybrid vehicle. Diesel engines compared to gasoline engines have the advantages of higher fuel economy and lower CO₂ emission. One of the most ways to meet future fuel economy and emissions regulation is to combine diesel engine technology with a hybrid electric vehicle. The simulation of HEV is growing need for rapid analysis of the many configurations and component options. WAVE, a one-dimensional engine analysis tool, was used to a 2.7L diesel engine. ADVISOR, designed for rapid analysis of the performance and fuel economy of vehicle models, was used to conventional and hybrid electric vehicle by the use of output file from WAVE as the input engine data file for ADVISOR. A parallel diesel HEV is at least 19.7~36% higher fuel economy and improved acceleration ability compared to a conventional diesel vehicle. The energy loss of the parallel diesel HEV is 23~38% less than the conventional vehicle using regeneration.

LPG - DME 압축착화 엔진의 성층화 영향

염기태(Kitae Yeom),배충식(Choongsik Bae) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.1

The exhaust emission characteristics of a liquefied petroleum gas?di-methyl ether (LPG-DME) compression ignition engine was investigated under homogeneous charge, stratified charge and diffusion combustion conditions. LPG was used as the main fuel and injected into the combustion chamber directly. DME was used as an ignition promoter and injected into the intake port. Different LPG injection timings were tested to verify the combustion characteristics of the LPG-DME compression ignition engine. The combustion was divided into three region which are homogeneous charge, stratified charge, and diffusion combustion region according to the injection timing of LPG. The HC emission was reduced with LPG stratification. However, the carbon monoxide and particulate matter emissions were increased. The ignition timing was advanced with LPG stratification. This advance combustion was because of charge temperature and cetane number stratification with LPG.

Top-Feed Type 인젝터의 LPG 액상분사 적용성

염기태(Kitae Yeom),박정서(Jungseo Park),장진영(Jinyoung Jang),문석수(Seoksu Moon),배충식(Choongsik Bae),박정남(Jeongnam Park),김성근(Sungkun Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The injection and spray characteristics of Top-feed type injector was investigated under liquid phase injection fueled with liquefied petroleum gas (LPG). Different pressures and temperatures of fuel injection system were tested to identify the injection characteristics after hot soaking. MIE-scattering technique was used for verification of successful liquid phase injection after hot soaking. In case of Bottom-feed type injector, the injection was accomplished at every experimental condition. In case of Top-feed type injector, when the pressure of LPG was over 12 bars, the injection was not executed. The effects of temperature of fuel on fuel injector were little. However, under the pressure were 12 bars, the liquid phase injection after hot soaking was accomplished.

LPG 예혼합 압축 착화 엔진의 배기가스 및 연소 특성

염기태(Kitae Yeom),장진영(Jinyoung Jang),배충식(Choongsik Bae) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.4

This paper investigates the steady state combustion characteristics of LPG homogeneous charge compression ignition (HCCI) engine with variable valve timing (VVT) and di-methyl ether (DME) direct injection, to find out the benefits in exhaust gas emissions. VVT is one of the attractive ways to control HCCI engine. Hot internal residual gas which is controlled by VVT device, makes fuel is evaporated easily, and ignition timing is advanced. Regular gasoline and liquefied petroleum gas (LPG) were used as main fuel and di-methyl ether (DME) was used as ignition promoter in this research. Operating range and exhaust emissions were compared LPG HCCI engine with gasoline HCCI engine. Operating range of LPG HCCI engine was wider than that of gasoline HCCI engine. The start of combustion was affected by the intake valve open (IVO) timing and the λTOTAL due to the latent heat of vaporization, not like gasoline HCCI engine. At rich operation conditions, the burn duration of the LPG HCCI engine was longer than that of the gasoline HCCI engine. CAD at 20% and 90% of the mass fraction burned were also more retarded than that of the gasoline HCCI engine. And carbon dioxide (CO2) emission of LPG HCCI engine was lower than that of gasoline HCCI engine. However, carbon oxide (CO) and hydro carbon (HC) emission of LPG HCCI engine were higher than that of gasoline HCCI engine.