• Title/Summary/Keyword: Homogeneous Charge Compression Ignition

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An Experimental Study on the Two Stage Ignition of Cool Flame and Hot Flame in HCCI Engine According to Fuel Composition (연료조성에 따른 HCCI 엔진의 냉염 및 열염의 2단연소 특성에 관한 실험적 연구)

  • 이기형;김형민;류재덕;이창식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.17-24
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    • 2004
  • As the environmental pollution becomes serious global problem, the regulation of emission exhausted from automobiles is strengthened. Therefore, it is very important to know how to reduce the NOx and PM simultaneously in diesel engines, which has lot of merits such as high thermal efficiency, low fuel consumption and durability. By this reason, the new concept called as Homogeneous Charge Compression Ignition(HCCI) engines are spotlighted because this concept reduced NOx and P.M. simultaneously. However, it is well known that HCCI engines increased HC and CO. Thus, the investigation of combustion characteristics which consists cool and hot flames for HCCI engines were needed to obtain the optimal combustion condition. In this study, combustion characteristics for direct injection type HCCI engine such as quantity of cool flame and hot flame, ignition timing and ignition delay were investigated to clarify the effects of these parameters on performance. The results revealed that diesel combustion showed the two-stage ignition of cool flame and hot flame, the rate of cool flame increase and hot flame decrease with increasing intake air temperature. On the other hand, the gasoline combustion is the single-stage ignition and ignition timing is near the TDC. In addition mixed fuel combustion showed different phenomenon, which depends on the ratio of gasoline component. Ignition timing of mixed fuel is retarded near the TDC and the ignition delay is increased according to ratio of gasoline.

An Investigation about Combustion and Emission Characteristics for Pilot Injection Timing on Partially Premixed Charge Combustion Ignition Engine Fueled with DME (파일럿 분사시기에 따른 DME 부분 예혼합 압축착화 엔진의 연소 및 배기특성에 관한 연구)

  • Jeong, Jaehoon;Lim, Ocktaeck;Pyo, Youngduck;Lee, Youngjae
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.3
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    • pp.43-49
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    • 2013
  • This work investigated the effects of engine speed and injection timing on combustion and emissions characteristics in a partially premixed charge compression ignition (pPCCI) engine fueled with DME. pPCCI engine especially has potential to achieve more homogeneous mixture in the cylinder, which results in lower NOx and smoke emission. In this study single cylinder engine was equipped with common rail and injection pressure is 700 bar. Total injected fuel mass is 64.5 $mm^3$ per cycle. The amount of pilot injection of the entire injection 12.5% is tested. Results show that NOx emission is decreased while IMEP is increased as the retard of injection timing. Besides, NOx emissions are slightly rised as well as IMEP is increased with the increase of engine speed.

Effect of Cooled-EGR on the Characteristics of Performance and Exhaust in a HCCI Diesel Engine (균일 예혼합 압축 착화 디젤 엔진의 성능 및 배출물 특성에 미치는 Cooled-EGR 효과)

  • Lee, Chang-Sik;Yoon, Young-Hoon;Kim, Myung-Yoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.5
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    • pp.35-41
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    • 2005
  • The effects of cooled-ECR on the characteristics of combustion and exhaust emissions were investigated in a single cylinder HCCI diesel engine The premixed charge (gasoline or diesel) was obtained with premixing chamber and high-pressure (5.5MPa) injection system. Exhaust pressure control and cooled ECR system were used in order to reduce pressure fluctuation and to mix the exhaust gas well with the fresh intake air. The experimental results show that NOx emissions from conventional diesel engine are steeply decreased by HCCI diesel combustion with cooled-EGR in both case of gasoline and diesel premixing. But soot emissions are rapidly increased with the increase of ECR rate. The recycled exhaust gas increased the ignition delay of mixture and decreased maximum combustion pressure. HC and CO emissions of HCCI combustion are increased with ECR rate.

Study on the Effect of Thermal Stratification on DME/n-Butane HCCI Combustion (열적성층화가 DME/n-Butane 예혼합압축자기착화연소에 미치는 영향에 관한 연구)

  • Lim, Ock-Taeck
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.12
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    • pp.1035-1042
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    • 2010
  • The thermal stratification effect has been thought as one of the way to avoid dramatically generating the heat from HCCI combustion. We investigate the effect of thermal stratification on HCCI combustion fueled by DME and n-Butane. The thermal stratification occurs in a combustion chamber of a rapid compression machine with premixture by buoyancy effect that is made of fuel and air. The premixture is then adiabatically compressed, and during the process, the in-cylinder gas pressure is measured and two-dimensional chemiluminescence images are prepared and analyzed. Under the thermal stratification, the LTR starting time and the HTR starting time are advanced than that of homogeneous case. Further, the LTR period and the luminosity duration under homogeneous conditions are shorter than the corresponding quantities under stratified conditions. Additionally, under stratified conditions, the brightest luminosity intensity is delayed longer than that of homogeneous condition.

Effect of Operation Condition on the Characteristics of Combustion and Exhaust Emissions in a Gasoline Fueled HCCI Diesel Engine (가솔린 균일 예혼합 압축 착화 디젤기관의 연소 및 배기 특성에 미치는 운전조건의 영향)

  • 이창식;김명윤;황석준;김대식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.48-54
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    • 2004
  • The purpose of this work is to investigate the effect of premixing condition on the combustion and exhaust emission characteristics in a HCCI diesel engine. To from homogeneous charge before intake manifold, the premixed gasoline fuel is injected into a premixed tank by fuel injection system and the premixed gasoline fuel is ignited by direct injected diesel fuel. Experimental result shows the NOx and soot emissions are decreased linearly with the increase of premixed ratio. In the case of intake air temperature $20^{\circ}C$ with light load, the specific fuel consumptions are increased with the rise of premixed ratio and HC and CO emissions are also increased. But the intake air heating can improve the specific fuel consumption at light load condition because increased air temperature promotes the combustion of premixed mixture. In the case of high intake air temperature with high load condition, premixed fuel is auto-ignited before diesel combustion and soot emission is increased.

Effects of Fuel Composition and Pressure on Autoignition Delay of Biomass Syngas (혼합비율 및 압력 변화가 바이오매스 합성가스의 점화지연 시간에 미치는 영향)

  • Shim, Tae Young;Kang, Ki Joong;Lu, Xingcai;Choi, Gyung Min;Kim, Duck Jool
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.12
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    • pp.945-952
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    • 2015
  • The autoignition characteristics of biosyngas were investigated both numerically and experimentally. The effects of the temperature, gas composition, and pressure on the autoignition characteristics were evaluated. A shock tube was employed to measure the ignition delay times of the biosyngas. The numerical study on the ignition delay time was performed using the CHEMKIN-PRO software to validate the experimental results and predict the chemical species in the combustion process. The results revealed that the ignition delay time increased with an increase in the hydrogen fraction in the mixture. Under most temperature conditions, the ignition delay time decreased with a pressure increase. However, the ignition delay time increased with an increase in pressure under relatively low temperature conditions.

A Study on Combustion and Emission Characteristics of a Diesel Engine Fuelled with Premixed Gasoline/Pilot Diesel (디젤 엔진에서 예혼합 가솔린/파일럿 디젤 이종연료의 연소 및 배출가스 특성에 관한 연구)

  • Kim, Minjae;Lim, Jonghan;Kang, Kernyong;Lee, Seokhwan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.25 no.3
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    • pp.326-335
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    • 2017
  • It is known that diesel engines have the disadvantage of high emission levels of NOx and PM. Therefore, many combustion strategies have been developed to reduce these harmful NOx and PM emissions in a diesel engine. Among these strategies, HCCI(Homogeneous Charge Compression Ignition) and PCCI(Premixed Charge Compression Ignition) are the most popular as these can reduce NOx and PM simultaneously. However, when a single fuel like diesel is applied, it is difficult to control the combustion phase and this can lead to power reduction. In this study, premixed gasoline and pilot diesel were used to overcome the problems of controllability of the combustion phase and harmful emissions. We injected gasoline directly into the combustion chamber and the gasoline/air mixture was ignited with a pilot diesel fuel near the top dead center. The results showed that the combustion and emission characteristics of dual-fuel combustion were comparable to those of conventional diesel combustion. When we applied the dual-fuel PCCI combustion concept, more than 90 % of NOx and PM emission was reduced simultaneously without significant degradation of efficiency compared to conventional diesel combustion.

Effect of Premixed Fuels Charge on Exhaust Emission Characteristics of HCCI Diesel Engine (HCCI 디젤엔진의 배기특성에 미치는 예혼합 연료의 영향)

  • Kim Myung Yoon;Yoon Young Hoon;Hwang Suk Jun;Kim Dae Sik;Lee Chang Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.4
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    • pp.182-189
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    • 2005
  • In order to investigate the effect of premixed gasoline, diesel fuel, and n-heptane charges on the combustion and exhaust emission characteristics in a direct injection (DI) diesel engine, the experimental studies are performed. The premixed fuels are injected into the premixing chamber that installed upstream of the intake port in order to minimize the inhomogeneity effect of premixed charge. The injection nozzle for directly injected fuel is equipped in the center of the combustion chamber. The air temperature control system is equipped in the intake manifold to examine the effect of air temperature. The experimental results of this study show premixing fuel is effective method to reduce the NOx and soot emissions of diesel engine. NOx emissions are linearly decreased with increasing premixed ratio for the three kinds of premixed fuels. The heating of intake air $(80^{\circ}C)$ reduced the deterioration of BSFC in high premixed ratio, because it promotes evaporation of premixed diesel droplet in the premixing chamber.

An Analysis on the Effects of EGR to Extend Operation Region for a HCCI Hydrogen Engine (HCCI 수소기관에서 운전영역확장을 위한 EGR 효과 분석)

  • LEE, KEONSIK;KIM, JINGU;BYUN, CHANGHEE;LEE, JONGTAI
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.6
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    • pp.560-566
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    • 2015
  • HCCI (Homogeneous Charge Compression Ignition) hydrogen engine has relatively narrower operation range caused by knock occurrence due to the rapid pressure rising by using higher compression ratio. In this study, EGR as one of the countermeasure methods is considered to extend operation range of HCCI hydrogen engine. Also, the effects of hydrogen EGR are compared with the effects of EGR using hydrocarbon fuel. Hydrocarbon EGR is carried out by adding carbon dioxide to exhaust gas of HCCI hydrogen engine. As the results, EGR has positive effects on a HCCI hydrogen engine in reducing rate of pressure rise as same as the other engines used hydrocarbon fuels. However, the effects of hydrogen EGR are better than those of hydrocarbon EGR in decreasing minimum compression ratio and rate of pressure rise. When applying EGR to HCCI hydrogen engine by 20% rate, the rate of pressure rise decreases by 58% and it results in about 48% increase of the operation range in terms of supply energy.

Two-zone Modeling for Combustion Processes of HCCI Engine (균일 예혼합 압축착화 엔진 연소과정의 Two-Zone 모델링)

  • Lee Myunghoon;Kim Kunhong;Kim Yongmo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.3
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    • pp.74-79
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    • 2005
  • The Homogeneous Charge Compression Ignition(HCCI) combustion is currently under intensive investigation because of its potential to increase thermal efficiency while greatly decreasing NOx and p.M. In order to account for the thermal boundary layer effects, the two-zone model has been developed to analyze the combustion characteristics of HCCI engine. The detailed chemistry are represented by the GRI mechanism 3.0 involving 53 species and 325reactions. The present combustion model has been validated against the experimental results. Computations are also made for the wide-range operating conditions of HCCI engine.