• Title/Summary/Keyword: Compression Ignition Engine

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Correlations for Predicting Viscosity of Vegetable Oils and Its Derivatives for Compression Ignition Engines

  • No, Soo-Young
    • Journal of ILASS-Korea
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    • v.14 no.3
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    • pp.122-130
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    • 2009
  • Vegetable oil and its derivatives as an alternative diesel fuel have become more attractive recently because of its environmental benefits and the fact that they are made from renewable resources. Viscosity is the most significant property to affect the utilization of vegetable oil and its derivatives in the compression ignition engines. This paper presents the existing correlations for predicting the viscosity of vegetable oil and its derivatives for compression ignition engines. According to the parameter considered in the correlations, the empirical correlations can be divided into six groups: correlations as a function of temperature, of proportion, of composition, of temperature and composition, of temperature and proportion, and of fuel properties. Out of physical properties of fuel, there exist in the literature several parameters for giving the influence on kinematic viscosity such as density, specific gravity, the ratio of iodine value over the saponification value, higher heating value, flash point and pressure. The study for the verification of applicability of existing correlations to non-edible vegetable oil and its derivatives is required.

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The Effects of Hydrogen on DME HCCI Combustion (DME 예혼합 압축착화 엔진에서 수소의 영향)

  • Baek, Cheul-Woo;Yoon, Hyeon-Sook;Yeom, Ki-Tae;Jang, Jin-Young;Bae, Choong-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.2
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    • pp.15-21
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    • 2007
  • The aim of this paper is controlling ignition timing and load in homogeneous charge compression ignition (HCCI) combustion with low cetane number fuel, hydrogen. Homogeneous charge compression ignition (HCCI) combustion is an advanced combustion technology that achieves higher thermal efficiency and lower $NO_x$ emissions than that of conventional combustion system. Dimethyl ether (DME), which has been researched widely as the most attractive alternative fuel of diesel, is attractive for HCCI combustion because of the easy evaporation. In this study, the single cylinder DME engine operated with a direct injection system has been used to investigate combustion processes and emissions of DME HCCI with a premixed hydrogen supply. The experiment was carried out under various engine speed and fraction rates of hydrogen. As a result, the increase of fraction rates of hydrogen retard the DME ignition timing and eliminated the knocking during high engine speed condition. IMEP was increased with increase of fraction rates of hydrogen by 30%. 40% of the fraction rates of hydrogen resulted in misfiring. The $NO_x$ emission was reduced by increasing the fraction rates of hydrogen, but HC emission was increased.

Emission Characteristics of HCNG Engine with Compression Ratio Change (압축비 변화에 따른 HCNG 엔진의 배기 특성)

  • Lee, Sungwon;Lim, Gihun;Park, Cheolwoong;Choi, Young;Kim, Changgi
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.4
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    • pp.106-112
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    • 2013
  • Compression ratio is an important factor affecting engine performance and emission characteristics since thermal efficiency of spark ignition engine can be theoretically improved by increasing compression ratio. In order to evaluate the effect of compression ratio change in HCNG engine, natural gas engine was employed using HCNG30 (CNG 70 vol%, hydrogen 30 vol%). Combustion and emission characteristics of CNG and HCNG fuel was analyzed with respect to the change of compression ratio at each operating condition. The results showed that thermal efficiency improved and $CH_4$, $CO_2$ emission decreased with the increase in compression ratio while $NO_x$ emissions were decreased at a certain excess air ratio condition. Higher thermal efficiency and further reduction of exhaust emissions can be achieved by the increase of compression ratio and the retard of spark timing.

Improvement of Thermal Efficiency using Atkinson Cycle in a High-Compression Ratio, Spark-Ignition, Natural Gas Engine for Power Generation (고압축비 전기점화 천연가스 발전용 엔진에서 앳킨슨 사이클 적용을 통한 열효율 향상)

  • Junsun Lee;Hyunwook Park;Seungmook Oh;Changup Kim;Yonggyu Lee;Kernyong Kang
    • Journal of ILASS-Korea
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    • v.28 no.2
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    • pp.55-61
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    • 2023
  • Natural gas is a high-octane fuel that is effective in controlling knocking combustion. In addition, as a low-carbon fuel with a high hydrogen-carbon ratio, it emits less carbon dioxide and almost no particulate matter compared to conventional fossil fuels. Stoichiometric combustion engines equipped with a three-way catalyst are useful in various fields such as transportation and power generation because of their excellent exhaust emission reduction performance. However, stoichiometric combustion engines have a disadvantage of lower thermal efficiency compared to lean combustion engines. In this study, a combination of high compression ratio and Atkinson cycle was implemented in a 11 liter, 6-cylinder, spark-ignition engine to improve the thermal efficiency of the stoichiometric engine. As a result, pumping and friction losses were reduced and the operating range was extended with optimized Atkinson camshaft. Based on the exhaust gas limit temperature of 730℃, the maximum load and thermal efficiency were improved to BMEP 0.66 MPa and BTE 35.7% respectively.

The prediction of performance and emissions of a spark ignition engine by cycle simulation (Cycle Simulation에 의한 가솔린기관의 성능과 배출물 예측)

  • 이종원;정진은
    • Journal of the korean Society of Automotive Engineers
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    • v.5 no.2
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    • pp.48-55
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    • 1983
  • The prediction of performance and emissions is presented for a spark ignition engine. a two zone, zero-dimensional model was employed which included thermodynamics, combustion and hear transfer, and a kinetic model employed for NOx. The model was used to analyze the processes of compression, combustion and expansion. Cylinder pressures and temperatures were calculated as a function of crankangle as well as engine performance and emissions. Predictions made with the simulation were compared with experimental data from a four cylinder spark ignition engine. Calculated pressures and, Co and Co$_{2}$ concentrations showed acceptable quantitative agreement with data. But calculated No concentrations were slightly different. A parametric study of the effect of variations in speed, combustion duration and spark timing was carried out. This simulation can be useful for design of spark ignition engines.

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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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Effects of optimal operating conditions on 2-stage injection PCCI diesel engine using Response Surface Methodology (반응 표면법을 이용한 2 단 분사 PCCI 디젤엔진의 운전조건의 영향도 평가에 대한 연구)

  • Lee, Jae-Hyeon;Kim, Hyung-Min;Lee, Ki-Hyung
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.3044-3048
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    • 2008
  • It is well known that Premixed Charge Compression Ignition (PCCI) diesel engines according to many technologies such a change in injection timing, multiple injection strategy, cooled EGR, intake charging and SCV have the potential to achieve homogeneous mixture in the cylinder which result in lower NOx and PM as well as performance improvements. This may generate merely the infinite number of experimental conditions. The use of Response Surface Methodology (RSM) technique can considerably pull down the number of experimental set and time demand. This paper presents the effects of both fuel injection and engine operation conditions on the combustion and emissions in the PCCI diesel engine system. The experimental results have revealed that a change in fuel injection timing and multiple injection strategy along with various operating conditions affect the combustion, emissions and BSFC characteristics in the PCCI engine.

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Performance and Emission Characteristics of a DI Diesel Engine Operated with LPG/DME Blended Fuel (LPG/DME 혼합연료를 사용하는 직접분사식 디젤 엔진의 부분부하 성능 및 배기특성에 관한 연구)

  • Lee, Seok-Hwan;Oh, Seung-Mook;Choi, Young;Cho, Jun-Ho;Cha, Kyoung-Ok
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.5
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    • pp.53-60
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    • 2009
  • In this study, LPG-blended DME fuel was experimentally investigated in CI(compression ignition) engine. In particular, performance, emissions characteristics (including hydrocarbon, CO, and NOx emissions), and combustion stability of engine fueled with LPG-blended DME fuel were examined. The extent of LPG fuel in the blended fuel was 0-40 wt%. Results showed that stable engine operation was possible in a wide range of engine loads on DME blended with maximum 30% of LPG by mass in a CI engine. Considering the results of the engine power output and exhaust emissions, blended fuel up to 30% of LPG by mass can be used as an alternative to diesel in a CI engine. LPG blended DME fuel is expected to have potential for enlarging the DME market.

Effect of EGR and Supercharging on the Diesel HCCI Combustion (디젤 예혼합 압축착화 엔진에서 배기가스 재순환과 과급의 영향)

  • Park, Se-Ik;Kook, Sang-Hoon;Bae, Choong-Sik;Kim, Jang-Heon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.5
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    • pp.58-64
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    • 2006
  • Homogeneous charge compression ignition(HCCI) combustion is an advanced technique for reducing the hazardous nitrogen oxide(NOx) and particulate matter(PM) in a diesel engine. NOx could be reduced by achieving lean homogeneous mixture resulting in combustion temperature. PM could be also reduced by eliminating fuel-rich zones which exist in conventional diesel combustion. However previous researches have reported that power-output of HCCI engine is limited by the high intensive knock and misfiring. In an attempt to extend the upper load limit for HCCI operation, supercharging in combination with Exhaust Gas Recirculation(EGR) has been applied: supercharging to increase the power density and EGR to control the combustion phase. The test was performed in a single cylinder engine operated at 1200 rpm. Boost pressures of 1.1 and 1.2 bar were applied. High EGR rates up to 45% were supplied. Most of fuel was injected at early timing to make homogeneous mixture. Small amount of fuel injection was followed near TDC to assist ignition. Results showed increasing boost pressure resulted in much higher power-output. Optimal EGR rate influenced by longer ignition delay and charge dilution simultaneously was observed.

The Effect of Hydrogen Enrichment on Exhaust Emissions and Thermal Efficiency in a LPG fuelled Engine

  • Park, Gyeung-Ho;Han, Sung-Bin;Chung, Yon-Jong
    • Journal of Mechanical Science and Technology
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    • v.17 no.8
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    • pp.1196-1202
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    • 2003
  • The concept of hydrogen enriched LPG fuelled engine can be essentially characterized as low emissions and reduction of backfire for hydrogen engine. The purpose of study is obtaining low-emission and high-efficiency in LPG engine with hydrogen enrichment. In order to determine the ideal compression ratio, a variable compression ratio single cylinder engine was developed. The objective of this paper is to clarify the effects of hydrogen enriched LPG fuelled engine on exhaust emission, thermal efficiency and performance. The compression ratio of 8 was selected to minimize abnormal combustion. To maintain equal heating value, the amount of LPG was decreased, and hydrogen was gradually added. In a similar manner, the relative air-fuel ratio was increased from 0.8 to 1.3 in increment of 0.1, and the ignition timing was controlled to be at MBT each case.