• Title/Summary/Keyword: Compression Ignition Engine

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Flame Characteristics of Diesel Spray in the Condition of Partial Premixed Compression Ignition (부분 예혼합 압축착화 조건에서 디젤분무의 화염특성)

  • Bang, Joong Cheol;Park, Chul Hwan
    • Journal of the Korean Society of Combustion
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    • v.17 no.2
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    • pp.24-31
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    • 2012
  • Diesel engines exhaust much more NOx(Nitrogen Oxides) and PM(Particulate Matter) than gasoline engines, and it is not easy to reduce both NOx and PM simultaneously because of the trade-off relation between two components. This study investigated flame characteristics of the partial premixed compression ignition known as new combustion method which can reduce NOx and PM simultaneously. The investigation was performed through the analysis of the flame images taken by a high speed camera from the visible engine which is the modified single cylinder diesel engine. The results obtained through this investigation are summarized as follows; (1) The area of the luminous yellow flame was reduced due to the decrease of flame temperature and even distribution of temperature. (2) The darkish yellow flame zone caused by the shortage of the remaining oxygen after the middle stage of combustion was considerably reduced. (3) Since the ignition delay was shortened, the violent combustion did not occur and the combustion duration became shortened.

Theoretical Prediction Method on Occurrence of Spark Knock (스파크노크 발생에 대한 이론적 예측방법)

  • 이내현;오영일;이성열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3326-3334
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    • 1994
  • To theoretically predict knock occurrence in S. I. engine as a function of engine design and operating parameters, transient local temperature and pressure, mixture density of flame front in combustion period are calculated. We next determined normal combustion period and auto ignition period of end gas using the prediction method on occurrence of spark knock which we suggested. We predict knock occurrence in S. I. engine by comparing consecutively normal combustion period with the auto ignition period of end gas in combustion period. Engine design and operating parameters such as compression ratio, engine speed, spark timing, inlet temperature and pressure are taken into account in this calculations. The predicted result are well matched with the experimental results in turbocharged engine. Therefore, this method will provide the systematic guideline for designing engines in view of knocking limits.

Combustion Characteristics of Premixed Charge Compression Ignition Diesel Engine using Mixed Fuels (혼합연료를 이용한 예혼합 압축착화 디젤엔진의 연소특성)

  • 조병호;이기형;이창식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.58-64
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    • 2002
  • A diesel engine has various merits such as high thermal-efficiency, superior fuel consumption and durability. Therefore the number of diesel engine in the world is increasing. As the seriousness of environmental pollution increases in the world, the method to reduce the noxious materials of CO2, NOx and P.M. is very important subject to correspond to exhaust gas regulations. A new concept, so called premixed charge compression ignition(PCCI), is focused among the various corresponding manners. In this study, we investigated the combustion characteristics of PCCI engine using a mixed fuels with that of commercial diesel engine. Finally we grasped a emission characteristics of PCCI engine. From this experiment, it could be found that NOx reduction is caused by the lower maximum temperature and soot reduction is caused by rapid combustion under diffusion combustion part. Also, it was found that 1st-combustion(cool flame) and 2nd-combustion(hot flame) is appeared in heat release curve, exhaust gas temperature is diminished and combustion variation is increased according to increasing of gasoline ratio.

An Experimental Study on the Combustion and Nanoparticle Emission Characteristics of Gasoline-diesel Fuel in a Premixed Charge Compression Ignition Engine (예혼합 압축착화 엔진에서 가솔린-디젤 연료의 연소 및 극미세입자 배출 특성에 관한 실험적 연구)

  • Yoon, Seung-Hyun;Lee, Doo-Jin;Lee, Chang-Sik
    • Journal of ILASS-Korea
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    • v.17 no.2
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    • pp.71-76
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    • 2012
  • The aim of this work was to investigate the combustion and nanoparticle emission characteristics of premixed charge compression ignition (PCCI) combustion at various test conditions using a single cylinder common-rail diesel engine. In order to create the homogeneity of fuel-air mixture, the premixed fuel (gasoline) was injected into premixing chamber during the intake process and then the diesel fuel was directly injected into the combustion chamber as an ignition source for the gasoline premixture. From these results, it revealed that the ignition delays and combustion durations were gradually prolonged and the peak combustion pressure were increased because diesel fuel was injected early injection timing with the increase of premixed ratio. In addition, as the increase of premixed ratio, total particle number is generally decreased and particle volume also indicated low levels at the direct injection timing from BTDC $20^{\circ}$ to TDC. At further advanced injection timing, total particle number and volume were generally increased

Combustion and Emission Characteristics in a High Compression Ratio Spark Ignition Engine using Off-gas from FT reaction (FT반응 Off-gas를 이용한 고압축비 전기점화 엔진의 연소 및 배기가스 특성에 관한 연구)

  • Chung, Tahn;Lee, Junsun;Lee, Yonggyu;Kim, Changup;Oh, Seungmook
    • Journal of ILASS-Korea
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    • v.23 no.3
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    • pp.114-121
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    • 2018
  • FT process is a technology of chemical reactions that converts a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. During the FT process unreacted gas, known as Off-gas which has low-calorie, is discharged. In this study, we developed an engine that utilize simulated Off-gas, and studied the characteristics of the engine. The off-gas composition is assumed to be $H_2$ 70%, CO 15%, $CO_2$ 15% respectively. Under stoichiometric air-fuel ratio, the experiment was conducted at WOT and IMEP 0.3 Mpa changing compression ratio. Ignition timing was applied with MBT timing. Maximum indicated thermal efficiency 37% was achieved at compression ratio 15 under WOT. CO, $CO_2$ and $NO_x$ were influenced by changing compression ratio, and CO emission was satisfied with the US Tier 4 standard for nonroad engine over the entire experimental conditions.

An Experimental Study on Phenomenon of Backfire in H2 HCCI Engine (예혼합 압축착화 수소기관의 역화현상에 관한 실험적 연구)

  • Lee, Jongmin;Lee, Jonggoo;Lee, Kwangju;Lee, Jongtai
    • Journal of Hydrogen and New Energy
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    • v.26 no.1
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    • pp.28-34
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    • 2015
  • HCCI (Homogeneous Charged Compression Ignition) hydrogen engine has relatively narrower operation range caused by backfire occurrence due to the rapid pressure rising by using higher compression ratio and significant reaction velocity. In this study, to grasp of backfire process and characteristic in the HCCI research hydrogen engine, in-cylinder pressure, intake pressure and backfire limit range are analyzed with compression ratio and intake valve open timing, experimentally. As the result, it is observed that knock is occurred just before backfire occurrence in HCCI hydrogen engine but not spark igntion type, this phenomenon is always the same for the above variables. Also backfire limit range are expanded up to 50% for the more retarding intake valve open timing in this operating conditions.

A Study on Effect of the Intake Valve Timing and Injection Conditions on the PCCI Engine Performance (흡기밸브 닫힘 시기와 분사조건이 PCCI 엔진의 성능에 미치는 영향에 관한 연구)

  • Lee, Jae-Hyeon;Kim, Hyung-Min;Kim, Yung-Jin;Lee, Ki-Hyung
    • Journal of ILASS-Korea
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    • v.15 no.1
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    • pp.1-7
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    • 2010
  • As world attention has focused on global warming and air pollution, high efficiency diesel engines with low $CO_2$ emissions have become more attractive. Premixed diesel engines in particular have the potential to achieve the more homogeneous mixture in the cylinder which results in lower NOx and soot emission. Early studies have shown that the operation conditions such as the EGR, intake conditions, injection conditions and compression ratio are important to reduce emissions in a PCCI (Premixed Charge Compression Ignition) engine. In this study a modified cam was employed to reduce the effective compression ratio. While opening timing of the intake valve was fixed, closing timing of the intake valve was retarded $30^{\circ}$. Although Atkinson cycle with the retarded cam leads to a low in-cylinder pressure in the compression stroke, the engine work can still be increased by advanced injection timing. On that account, we investigated the effects of various injection parameters to reduce emission and fuel consumption; as a result, lower NOx emission levels and almost same levels of fuel consumption and PM compared with those of conventional diesel engine cam timing could be achieved with the LIVC system.

Flow and Combustion Characteristics according Control Strategy of Variable Valve Duration System for Compression Ignition Engine (압축착화기관용 가변밸브 듀레이션(VVD)시스템의 제어전략에 따른 유동 및 연소성능 해석)

  • Cho, Insu;Kim, Wootaek;Lee, Jinwook
    • Journal of ILASS-Korea
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    • v.25 no.2
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    • pp.45-50
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    • 2020
  • Recently, global warming and environmental pollution are becoming more important, and fuel economy is becoming important. Each automobile company is actively developing various new technologies to increase fuel efficiency. CVVD(Continuously Variable Valve Duration) system means a device that continuously changes the rotational speed of the camshaft to change the valve duration according to the state of the engine. In this paper, VVT(Variable Valve Timing) and CVVD were applied to a single-cylinder diesel engine, and the characteristics of intake and exhaust flow rate and in-cylinder pressure characteristics were analyzed by numerical analysis. In order to analyze the effect of CVVD on the actual engine operation, the study was performed by setting the valve control and injection pressure as variables in two sections of the engine operating region. As a result, In the case of applying CVVD, the positive overlap with the exhaust valve is maintained, thus it is possible to secure the flow smoothness of air and increase the volumetric efficiency by improving the flow rate. The section 2 condition showed the highest peak pressure, but the pressure rise rate was similar to that of the VVT 20 and CVCD 20 conditions up to 40 bar due to the occurrence of ignition delay.

Combustion Characteristics of Pre-mixed Charge Compression Ignition Engines with Natural Gas Applied to 4-Cylinders Diesel Engine (4기통 디젤기관에 적용한 천연가스 예혼합 압축착화 기관의 연소특성)

  • Jung, S.H.
    • Journal of Power System Engineering
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    • v.13 no.2
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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.

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A Study on Combustion and Exhaust Emission in Direct Injection Diesel Engine (직접분사식 디젤기관의 연소 및 배기에 관한 연구)

  • Kim, Du-Beom;Kim, Gi-Bok;Kim, Chi-Won;Han, Sung-Hyun
    • Journal of the Korean Society of Industry Convergence
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    • v.20 no.2
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    • pp.105-113
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    • 2017
  • Recently the direct injection diesel engine is the most efficient one available for road vehicles, so this fundamental advantage suggests the compression injection diesel engine are a wise choice for future development efforts. The compression ignition diesel engine, with its bigger compression ratios if compared to the SI engine, offers a higher thermodynamic efficiency, also additionally the diesel engine with its less pumping losses due to the throttled intake charge as in a SI engine has higher fuel economy. But the largest obstacle to the success of this engine is meeting emission standards for Nitric oxides and particulate matter while maintain fuel consumption advantage over currently available engines. Thus its use should be largely promoted, however, diesel engine emits more Nitric oxides and particulate matter than other competing one. There has been a trade-off between PM and NOx, so efforts to reduce NOx have increased PM and vice versa, but trap change this situation and better possibility emerge for treating NOx emission with engine related means, such as injection timing, equivalence ratio, charge composition, and engine speed. The common rail direct injection system is able to adjust the fuel injection timing in a compression ignition engine, so this electronically controlled injection system can reduce the formation of NOx gas without increase in soot. In this study it is designed and used the engine test bed which is installed with turbocharge and intercooler. In addition to equipped using CRDI by controlling injection timing with mapping modulator, it has been tested and analyzed the engine performance, combustion characteristics, and exhaust emission as operating parameters.