• 에너지공학
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• 제3권1호
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• pp.54-61
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• 1994

계단형태의 고온발생장치로서, 고온의 흐름을 형성하고 난류유동이 없이 일정한 혼합기류를 만들 수 있는 2단격막구조 충격파관 장치를 이용하여, 혼합을 동반하지 않는 분무의 착화과정에 관한 실험을 수행하였다. 본 실험에서는 충격파관 속에 하향으로 설치된 초음파 분무기에 의해 자유낙하 상태에 있는 예혼합 분무주를 만들어서 반사충격파에 의해 순간적으로 단열압축시켜서 착화 현상을 관찰하였다. 고온영역과 저온영역에서 얻어진 활성화에너지는 큰 차이가 나며 본 연구에서 얻은 착화지연의 실험결과는 통상의 분무착화 실험인 전기로법, 급속압축기법, 고온기류속에 연료를 분사하는 방법과 다른 현상을 보였다. 그 대표적인 결과에 대한 예로는 착화지연에 대한 압력 의존성과 연료분사율의 영향이 일반적인 분무의 결과에 비해 적게 나타났다.

• 동력기계공학회지
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• 제13권2호
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• pp.5-10
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• 2009

In recently, studies concerned to the diesel engine uses a natural gas as a fuel oil whose infra has been built already was approached to PCCI or HCCI with keeping a high thermal efficiency and reducing NOx and PM have been researching actively in normally single cylinder. An ignition source is required to bum the natural gas by a spark plug in gasoline engines, due to a higher auto-ignition temperature of natural gas. Then gas oil and DME were introduced as the ignition source. In this study as basic data for practical use of natural gas PCCI and HCCI engines, combustion characteristics and emission characteristics on 4-cylinders natural gas PCCI and HCCI engines with gas oil and DME as ignition sources were analyzed and the engine load range that is main object for practical use of PCCI and HCCI engines was made clearly by empirical experiment.

• 한국연소학회지
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• 제18권4호
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• pp.21-28
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• 2013

HCCI engines have mainly focused on achieving low temperature combustion in order to obtain higher efficiency and lower emission. One of practical difficulties in HCCI combustion is to control the start of combustion and subsequent combustion phasing. The choice of primary reference fuels in HCCI strategy is one of various promising solutions to make HCCI combustion ignition-controlled. The behavior of ignition delay to the frequency variation of sinusoidal velocity oscillation is computationally investigated under HCCI conditions of PRF75 using a reduced chemistry in a counterflow configuration. The second-stage ignition is more delayed as the higher frequency is imposed on nozzle velocity fluctuation whereas the first-stage ignition is not much influenced.

• LP가스
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• 제20권2호
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• pp.59-67
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• 2008

지난 4월 2일 GAS KOREA 2008 전시회가 개최된 서울무역전시장에서 '한국DME협회 분과발표회'가 열렸다. 이날 분과발표회에서는 'DME Demo 플랜트 현황소개(한국가스공사 연구 개발원 조원준 박사 "DME 연료실증, 시험연구 사업현황(한국가스공사 연구개발원 백영순 박사)" 커먼레일형 연료공급계를 탑재한 2리터급 DME 차량개발(자동차 부품연구원 정재우 박사) "급속압축장치를 이용한 불균일 예혼합기의 DME HCCI연소 과정에 관한 연구(울산대학교 임옥택 교수) DME의 자착화 측정 및 세탄가의 추정(인하대학교 이대엽교수)" 직접분사식 압축착화기관에서 DME연료의 분무미립화 및 배출물 특성(한양대학교 이창식 교수)' 에 대한 발표도 이뤄졌다.

• 동력기계공학회지
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• 제16권6호
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• pp.19-23
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• 2012

DME HCCI기관의 단점은 디젤 엔진에 비해 기관부하 영역이 굉장히 좁다는 것이고 이는 저온산화반응이 너무 빨리 일어나서 노크를 발생시키기 때문이다. 저온산화반응을 억제하기 위해서 DME 연소에 미치는 천연가스의 영향을 실험한 결과, 천연가스가 DME의 저온산화반응을 억제시키기 때문에 기관부하영역이 확대된다는 것을 알았다. 본 연구에서는 서로 다른 세탄가를 가진 첨가연료가 DME 저온산화반응에 미치는 영향을 실험적으로 조사하였다. 그 결과 저온산화반응의 최고 열발생율은 세탄가에 의존하지 않지만 착화온도는 세탄가에 의존한다는 사실을 밝혔다.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.83-90
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• 2004

A flywheel-driven rapid compression and expansion machine is developed and utilized for experimental study of homogeneous charge compression ignition combustion. Compression ignition of homogeneous charge in IC engines offers possibilities of realizing ultra-lean engine operation with greatly reduced NOx and particulate formation. Fundamental investigations are carried out in order to better understand this ideal engine combustion mechanism. Perfectly premixed propane-air mixtures of various equivalence ratio are compression-ignited in the rapid compression and expansion machine, and the characteristics of the auto-ignition and the following combustion process are analyzed.

• 한국자동차공학회논문집
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• 제16권4호
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• pp.151-158
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• 2008

Gasoline Homogeneous Charge Compression Ignition (HCCI) combustion is a new combustion concept. Unlike the conventional internal combustion engine, the premixed fuel mixture with high residual gas rate is auto-ignited and burned without flame propagation. There are several operating factors which affect HCCI combustion such as start of combustion (SOC), residual gas fraction, engine rpm, etc. Among these factors SOC is a critical factor in the combustion because it affects exhaust gas emissions, engine power, fuel economy and combustion characteristics. Therefore SOC of gasoline HCCI should be controlled precisely, and SOC detection should be preceded SOC control. This paper presents a control oriented SOC detection method using 50 percent normalized difference pressure. Normalized difference pressure is defined as the normalized value of difference pressure and difference pressure is difference between the in-cylinder firing pressure and the motoring pressure. These methods were verified through the HCCI combustion experiments. The SOC detection method using difference pressure provides a fast and precise SOC detection.

• 대한기계학회논문집B
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• 제31권8호
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• pp.672-679
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• 2007

The combustion characteristics of a liquefied petroleum gas-di-methyl ether (LPG-DME) compression ignition engine was investigated under homogeneous charge and stratified charge 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 flame region according to the injection timing of LPG. The hydrocarbon emission of stratified charge combustion was lower than that of homogeneous charge combustion. However, the carbon monoxide and nitrogen oxide emission of stratified charge combustion were slightly higher than those of the homogeneous charge region. The indicated mean effective pressure was reduced at stratified charge region, while it was almost same level as the homogeneous charge combustion region at diffusion combustion region. The start of combustion timing of the stratified charge combustion and diffusion combustion region were advanced compared to the homogeneous charge combustion. It attributed to the higher cetane number and mixture temperature distribution which locally stratified. However, the knock intensity was varied as the homogeneity of charge was increased.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.78-85
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• 2008

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.

• 한국수소및신에너지학회논문집
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• 제23권6호
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• pp.628-633
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• 2012

It was found that the pure hydrogen-air pre-mixture was self-ignited at a high compression ratio without any assisting method in room temperature, thus refuting the preconception that compression ignition of hydrogen engine was impossible. Therefore, in order to analyze the correlation of compression ignition condition at cold start with hydrogen HCCI engine clearly, the possibility of compression igniting compression ratio is investigated with the change of equivalence ratio and engine speed, experimentally. As the results, it is confirmed that the possibility of compression-igniting compression ratio at cold start was decreased by increasing equivalence ratio due to decreasing auto-ignition temperature. In addition, it is grasped that the possibility of compression-igniting compression ratio at cold start is decreased around 14.9% by increasing engine speed at same supply energy.