• 한국자동차공학회논문집
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• 제14권6호
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• pp.9-16
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• 2006

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.

• International Journal of Automotive Technology
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• 제7권3호
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• pp.251-259
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• 2006

For practical application on the HCCI engine, the solution of subjects, such as control of auto-ignition timing and avoidance of knocking, is indispensable. This study focused on the technique of controlling HCCI combustion appropriately, changing the mixture ratio of two kinds of fuel. Methane and DME/n-Butane were selected as fuels. The influences, which the mixing ratio of two fuels does to ignition timing, ignition temperature, rate of heat release and oxidation reaction process, were investigated by experiment with 4-stroke HCCI engine and numerical calculation with elementary reactions.

• 오토저널
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• 제14권4호
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• pp.1-5
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• 1992

1. 노킹의 발생. 2. 노킹 발생 이후의 압력파. 3. 노킹 발생과 엔진 손상 부위. 4. 엔진손상 방지책.

• 한국자동차공학회논문집
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• 제17권4호
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• pp.32-39
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• 2009

The HCCI engine is a next generation engine, with high efficiency and low emissions. The engine may be an alternative to SI and DI engines; however, HCCI's operating range is limited by an excessive rate of pressure rise during combustion and the resulting engine knock in high-load. The purpose of this study was to gain a understanding of the effect of only initial temperature and thermal stratification for reducing the pressure-rise rate in HCCI combustion. And we confirmed characteristics of combustion, knocking and emissions. The engine was fueled with Di-Methyl Ether. The computations were conducted using both a single-zone model and a multi-zone model by CHEMKIN and modified SENKIN.

• 기술사
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• 제34권2호
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• pp.31-36
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• 2001

The Otto Cycle of conventional gasoline engine has no difference between compression ratio and expension ratio. because of the same length of 4 strokes : Intake, compression, expension, exhaust. On the other hand, miller cycle engine achieves both low-compression ratio and high-compression ratio by shortening the length of compression stroke among 4 strokes. Therefore miller cycle engine is essential for lessening knocking and improving heat efficiency. This paper Is designed to discribe not only principle and the development trend of miller cycle engine but also the control system and the technical characteristics of it.

• 한국가스학회지
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• 제22권6호
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• pp.34-39
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• 2018

최근 탈석유 에너지 이행의 목표가 분명해지는 가운데 천연가스가 가교연료로서 주목받고 있다. 천연가스는 옥탄가가 높아 압축비를 높여도 노킹이 일어나지 않기 때문에 열효율과 출력을 두루 향상시킬 수 있을 뿐 아니라 기존 내연기관 하드웨어 시스템에 천연가스 공급 시스템 적용을 비교적 용이하게 할 수 있다. 본 연구에서는 승용 가솔린 직분사 터보 엔진을 천연가스 포트분사식 터보 엔진으로 개조하여 터보가 작동되는 운전 영역에서 대상 엔진의 연소 및 성능을 종합적으로 측정 및 비교하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제20회 KOSCO SYMPOSIUM 논문집
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• pp.85-92
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• 2000

End-gas temperatures were measured using CARS technique in a conventional DOHC spark-ignition engine fueled with PRF80. The measured pressure data were analyzed using band pass filter method. The measured CARS temperatures were compared with adiabatic core temperatures calculated from measured pressure. Significant heating by pre-flame reaction in the end gas was observed in the late part of compression stroke under both knocking and non-knocking condition. CARS temperatures measured at 10 crank angle degree before knock occurrence was higher than adiabatic core temperatures. These results indicate that there exist some exothermic reactions in low pressure and temperature region. CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached 700 K. The temperature elevation due to the pre-flame reaction correlated better with CARS temperature than with cylinder pressure.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.32-41
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• 1999

In this study, a new knocking control algorithm was developed using the knock threshold value auto-correction algorithm. This algorithm uses the Fast Fourier Transform9FFT) method by measuring cylinder block vibration signals of a 1498 cc four-cylinder spark ignition engine. The experimental results show the proposed knock control algorithm provides improved performance compared to existing methods. The results also show that the proposed FFT algorithm provides real-time adjustment of the knock threshold value.

• 한국가스학회지
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• 제12권3호
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• pp.13-19
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• 2008

열병합발전용으로 사용되는 여러 가지 원동기 중 천연가스 엔진은 1 MW 이하의 발전용량을 갖는 원동기로 가장 널리 사용되고 있다. 이론공연비 연소방식과 삼원촉매를 채택한 300 kW급 천연가스 엔진은 강화된 배기규제를 만족시킬 수 있지만 이론공연비 연소방식은 희박 연소방식에 비해 효율이 대체적으로 낮기 때문에 최적 점화시기(MBT) 제어가 필요하다. 그러나 MBT 운전조건은 노킹이 발생되기 쉬워 높은 흡기온도 조건에서 운전되는 엔진에 대해서는 노킹제어가 이루어져야 한다. 본 연구에서는 높은 흡기온도가 요구되는 열병합발전용 천연가스엔진을 대상으로 흡기온도에 따른 엔진성능과 노킹특성에 대하여 실험한 결과를 제시하였다.

• 한국가스학회지
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• 제19권6호
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• pp.8-14
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• 2015

합성가스(SNG)는 석탄 가스화를 통하여 얻어지는 가스연료로서, 고유가로 인한 천연가스가격 상승을 대비할 수 있는 대체연료 중의 하나로 주목받고 있다. 본 연구에서는 메탄 90.95%, 프로판 6.05%와 수소 3%의 조성비를 갖는 SNG연료 모사가스와 압축천연가스 (CNG)를 11리터 급 CNG 엔진에 적용하여 연소 및 배기 특성을 비교실험 하였다. 연료공급시스템, 분사시기 등 엔진의 연소제어인자를 일정하게 하고 전부하 운전조건에서 엔진회전수 변화에 따른 출력, 열효율, 연소 안정성 및 배기특성을 비교하였다. 1260rpm, 전부하 운전조건에서 노킹특성도 분석하였다. SNG 연료를 사용했을 때 출력 저하 없이 연소안정성이 향상되어 열효율이 증가하였다. 질소산화물($NO_x$)의 배출은 CNG연료의 경우에 비해 증가되었으나 이산화탄소($CO_2$)의 배출은 감소하였다. SNG 연료를 이용하여 운전할 경우 내노킹성이 향상되었다.