• Title/Summary/Keyword: Homogeneous Charge Compression Ignition

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Knock Characteristic Analysis of Gasoline and LPG Homogeneous Charge Compression Ignition Engine (가솔린과 LPG 예혼합 압축 착화 엔진의 노킹 특성)

  • Yeom, Ki-Tae;Bae, Choong-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.3
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    • pp.54-62
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    • 2007
  • 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 6.5MPa. 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.

A Study on the Spray and Combustion Characteristics of a HCCI Engine according to Injection Conditions using a Narrow Angle Injector (좁은 분사각을 갖는 인젝터를 이용한 예혼합 압축착화 엔진의 분사조건에 따른 분무 및 연소특성에 관한 연구)

  • Kim, Hyung-Min;Kim, Yung-Jin;Ryu, Jea-Duk;Lee, Ki-Hyung
    • Journal of ILASS-Korea
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    • v.11 no.3
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    • pp.161-167
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    • 2006
  • As the exhaustion of petroleum resources and air pollution problems are getting serious recently, there are growing interests in premixed diesel engines which have the potential of achieving a more homogeneous mixture near TDC compared to conventional diesel engines. Early studies have shown that the fuel injection frequency and spray angle affected the mixture formation and combustion in a HCCI(Homogeneous Charge Compression Ignition) engine. Therefore, the purpose of this study is to investigate the relationship between combustion and mixture formations by injection timing and frequency using a narrow angle injector, NADI (Narrow Angle Direct Injection). In this study, we found that the fuel injection timing and injection frequency affect the mixture formations and then affect combustion in the HCCI engine.

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HCCI Combustion of DME in a Rapid Compression and Expansion Machine (급속압축팽창기를 이용한 DME의 HCCI 연소)

  • Sung, Yong-Ha;Jung, Kil-Sung;Choi, Byung-Chul;Lim, Myung-Taeck
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.2
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    • pp.8-14
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    • 2007
  • Compression ignition of homogeneous charges in IC engines indicates possibilities of achieving the high efficiency of DI diesel engines with low level of NOx and particulate emissions. The objectives of this study are to further understand the characteristics of the HCCI(Homogeneous charge compression ignition) combustion and to find ways of extending the rich HCCI operation limit in an engine-like environment. DME fuel is supplied either in the form of premixture with air or directly injected in the combustion chamber of a rapid compression and expansion machine under the conditions of various equivalence ratio and injection timing. The cylinder pressure is measured and the rate of heat release is computed from the measured pressure for the analysis of the combustion characteristics. The experimental data show that the RCEM can operate without knock on mixtures of higher equivalence ratio, when DME is directly injected in the combustion chamber than introduced as a fraction of a perfect or nearly perfect premixture. Very early fuel injection timings usually employed in HCCI operation are seen to have only insignificant effects in control of ignition timing.

EFFECT OF ADDITIVE ON THE HEAT RELEASE RATE AND EMISSIONS OF HCCI COMBUSTION ENGINES FUELED WITH RON90 FUELS

  • Lu, X.C.;Ji, L.B.;Chen, W.;Huang, Z.
    • International Journal of Automotive Technology
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    • v.8 no.1
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    • pp.1-7
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    • 2007
  • The effect of the di-tertiary butyl peroxide (DTBP) additive on the heat release rate and emissions of a homogeneous charge compression ignition (HCCI) engine fueled with high Research Octane Number (RON) fuels were investigated. The experiments were performed using 0%, 1%, 2%, 3%, and 4% (by volume) DTBP-RON90 blends. The RON90 Fuel was obtained by blending 90% iso-octane with 10% n-heptane. The experimental results show that the operation range was remarkably expanded to lower temperature and lower engine load with the DTBP additive in RON90 fuel. The first ignition phase of HCCI combustion was observed at 850 K and ended at 950 K while the hot ignition occurred at 1125 K for all fuels at different engine working conditions. The chemical reaction scale time decreases with the DTBP addition. As a result, the ignition timing advances, the combustion duration shortens, and heat release rates were increased at overall engine loads. Meanwhile, the unburned hydrocarbon (UHC) and CO emissions decrease sharply with the DTBP addition while the NOx emissions maintain at a lower level.

An Investigation of HCCI Combustion Processes of Stratified Charge Mixture Using Rapid Compression Machine (급속압축 장치를 이용한 불균일 예혼합기가 HCCI연소에 미치는 영향에 관한 연구)

  • Lim, Ock-Taeck
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.3
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    • pp.8-14
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    • 2009
  • Effect of heterogeneity of combustion chamber has been thought as one of the way to avoid dramatically generating heat in HCCI Combustion. The purpose of this research is to investigate the effect of heterogeneity, especially thermal stratification and fuel strength stratification on HCCI Combustion fueled with DME and n-Butane. Thermal stratification is formed in Combustion Chamber of Rapid Compression Machine with 3 Kinds of pre-mixture has different properties. The stratified charge mixture is adiabatic compressed and on that process, in cylinder gas pressure and two-dimensional chemiluminescence images are measured and analyzed.

An Experimental Study on the Combustion and Emission Characteristics According to the Variation of Compression Ratio and Intake Temperature Using Stratified Charge Compression Ignition in a Gasoline Direct Injection Engine (SCCI 방법을 이용한 직분식 가솔린 엔진내의 압축비 및 흡기 온도 변화에 따른 연소 및 배기 특성에 관한 실험적 연구)

  • Lee Chang-Hee;Lee Ki-Hyung;Lim Kyoung-Bin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.6 s.249
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    • pp.538-545
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    • 2006
  • Stratified charge compression ignition (SCCI) combustion, also known as HCCI(homogeneous charge compression ignition), offers the potential to improve fuel economy and reduce emission. In this study, SCCI combustion was studied in a single cylinder gasoline DI engine, with a direct injection system. We investigated the effects of air-fuel ratio, intake temperature and injection timing such as early injection and late injection on the attainable SCCI combustion region. Injection timing during the intake process was found to be an important parameter that affects the SCCI region width. We also find it. The effects of mixture stratification and fuel reformation can be utilized to reduce the required intake temperature for suitable SCCI combustion under each set of engine speed and compression ratio conditions.

Numerical Study on the Effect of Diesel Injection Parameters on Combustion and Emission Characteristics in RCCI Engine (RCCI 엔진의 디젤 분사 파라미터에 따른 연소 및 배출가스 특성에 대한 수치적 연구)

  • Ham, Yun-Young;Min, Sunki
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.6
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    • pp.75-82
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    • 2021
  • Low-temperature combustion (LTC) strategies, such as HCCI (Homogeneous Charge Compression Ignition), PCCI (Premixed Charge Compression Ignition), and RCCI (Reactivity Controlled Compression Ignition), have been developed to effectively reduce NOx and PM while increasing the thermal efficiency of diesel engines. Through numerical analysis, this study examined the effects of the injection timing and two-stage injection ratio of diesel fuel, a highly reactive fuel, on the performance and exhaust gas of RCCI engines using gasoline as the low reactive fuel and diesel as the highly reactive fuel. In the case of two-stage injection, combustion slows down if the first injection timing is too advanced. The combustion temperature decreases, resulting in lower combustion performance and an increase in HC and CO. The injection timing of approximately -60°ATDC is considered the optimal injection timing considering the combustion performance, exhaust gas, and maximum pressure rise rate. When the second injection timing was changed during the two-stage injection, considering the combustion performance, exhaust gas, and the maximum pressure increase rate, it was judged to be optimal around -30°ATDC. In the case of two-stage injection, the optimal result was obtained when the first injection amount was set to approximately 60%. Finally, a two-stage injection rather than a single injection was considered more effective on the combustion performance and exhaust gas.

An Experimental Study on Correlation of Compression Ignition Condition at Cold Start with Hydrogen HCCI Engine (냉시동시 압축착화 조건의 상관관계에 관한 수소 HCCI 기관의 실험적 연구)

  • Lee, Kwangju;Lee, Jonggoo;Ahn, Byunghoh;Lee, Jongtai
    • Transactions of the Korean hydrogen and new energy society
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    • v.23 no.6
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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.

The investigation on the Ignition Delay of n-heptane/n-butanol Blend Fuel using a Rapid Compression Machine at Low Temperature Combustion Regime (저온연소조건에서 급속압축기를 이용한 n-heptane/n-butanol 혼합연료의 착화지연에 관한 연구)

  • Song, Jaehyeok;Kang, Kijoong;Yang, Zheng;Lu, Xingcai;Choi, Gyungmin;Kim, Duckjool
    • 한국연소학회:학술대회논문집
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    • 2013.06a
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    • pp.25-28
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    • 2013
  • This study presents both experimental and numerical investigation of ignition characteristics of n-heptane and n-butanol mixture. The $O_2$ concentration was fixed to 9-10% to make high exhaust gas recirculation(EGR) rate condition. Experiments were performed using a rapid compression machine. In addition, a numerical study of the ignition delay time was performed using CHEMKIN codes to validate experimental results and predict chemical species after combustion process. The results showed that the ignition delay time increased with increasing n-butanol ratio and the reactivity decreased by low $O_2$ concentration.

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