• Title/Summary/Keyword: Direct combustion

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Comparison of Combustion Characteristics with Combustion Strategy and Excess Air Ratio Change in a Lean-burn LPG Direct Injection Engine (직접분사식 LPG 엔진의 연소전략 및 공기과잉률 변화에 따른 연소특성 비교)

  • Cho, Seehyeon;Park, Cheolwoong;Oh, Seungmook;Yoon, Junkyu
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.6
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    • pp.96-103
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    • 2014
  • Liquefied Petroleum Gas(LPG) has attracted attention as a alternative fuel. The lean-burn LPG direct injection engine is a promising technology because it has an advantage of lower harmful emissions. This study aims to investigate the effect of combustion strategy and excess air ratio on combustion and emission characteristics in lean-burn LPG direct injection engine. Fuel consumption and combustion stability were measured with change of the ignition timing and injection timing at various air/fuel ratio conditions. The lean combustion characteristics were evaluated as a function of the excess air ratio with the single injection and multiple injection strategy. Furthermore, the feasibility of lean operation with stratified mixture was assessed when comparing the combustion and emission characteristics with premixed lean combustion.

Analysis on Combustion Characteristics of CRDi Single-cylinder Diesel Engine with Direct Needle-driven Piezo Injector (직접구동 피에조 인젝터의 CRDi 단기통 디젤엔진 연소 특성 분석)

  • Chung, Myungchul;Sung, Gisu;Kim, Sangmyung;Lee, Jinwook
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.5
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    • pp.108-115
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    • 2014
  • In this study, experimental approaching method was applied under and single-cylinder engine to research the performance of direct needle-driven piezo injector (DPI) for CR direct-injection. As key-point factor of this DPI that relies on direct-acting operating of injector needle, unlike conventional hydraulic-servo, its nozzle needle can be directly driven by piezo actuator. Thus, effect of direct-acting injection of DPI on diesel combustion and emission characteristics was investigated under common-rail single-cylinder direct-injection engine, equipped with three different driving mechanism, including indirect-acting solenoid, piezo and DPI system. As main results, it found that a direct-acting piezo injector has higher of IMEP. And it has higher heat release rate during premixed combustion and mixing controlled combustion phase due to its higher heat release, even though nitrogen oxide (NOx) formations were increased slightly.

A Study on Ignition Probability and Combustion Characteristics of Low Pressure Direct Injection LPG according to a Function of Ambient Condition (분위기 조건 변화에 따른 저압 직접분사식 LPG의 점화성 및 연소특성 연구)

  • Chung, Sung-Sik;Hwang, Seong-Ill;Yeom, Jeong-Kuk;Jeon, Byong-Yeul
    • Journal of Power System Engineering
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    • v.20 no.2
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    • pp.32-42
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    • 2016
  • Under part load condition of spark-ignition engine, pumping loss had great effect on engine efficiency. To reduce pumping loss, the study designed spark-ignited engines to make direct spray of gasoline to combustion chamber. In spark-ignited direct-injection engines, ignition probability is important for successful combustion and flame propagation characteristics are also different from pre-mixed combustion. This study designed a visualization testing device to study ignition probability of spark-ignited direct-injection LPG fuel and combustion flame characteristics. This visualization device consists of combustion chamber, fuel supply system, air supply system, electronic control system and data acquisition system. Ambient pressure, ambient temperature and ambient air flow velocity are important parameters on ignition probability of LPG-air mixture and flame propagation characteristics, and the study also found that sprayed LPG fuel can be directly ignited by spark-plug under proper ambient conditions. To all successful cases of ignition, the study recorded flame propagation image in digital method through ICCD camera and its flame propagation characteristics were analyzed.

Direct Combustion Characteristics of Coal by Oxygen Carrier (산소공여입자에 의한 석탄의 직접연소 특성)

  • Ryu, Hojung;Lee, Chungwon;Lee, Dongho;Bae, Dalhee;Lee, Suengyong;Park, Yeongseong
    • Transactions of the Korean hydrogen and new energy society
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    • v.25 no.1
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    • pp.87-96
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    • 2014
  • Direct combustion characteristics of coal and oxygen carrier were measured in the thermogravimetric analyzer using four coals and two different oxygen carriers. The direct combustion efficiency decreased in order of Roto, Kideco, Sunhwa and Hyper coal for both oxygen carriers. Moreover, OCN703-1100 oxygen carrier showed better combustion efficiency than OCN706-1100 oxygen carrier for all four coals. The reduction characteristics of two oxygen carriers for $CH_4$, CO and $H_2$ gases were measured in the thermogravimetric analyzer to investigate why OCN703-1100 oxygen carrier showed better combustion efficiency than OCN706-1100 for all coals. The OCN703-1100 oxygen carrier represented higher reduction rate than OCN706-1100 for all reducing gases. Moreover, the total pore area and the porosity of OCN703-1100 were higher than those of OCN706-1100 oxygen carrier. The total volatile gas and volatile components of four coals were measured in a batch type fluidized bed reactor to investigate why the direct combustion efficiency decreased in order of Roto, Kideco, Sunhwa and Hyper coal for both oxygen carriers. The direct combustion efficiency was proportional to the total amount of ($CH_4+CO+H_2$) produced during devolatilization of coals.

The Influence of Fuel Spray Characteristics on the Engine Performance and Emission in the Direct Injection Type Diesel Engine

  • Bakar Rosli Abu;Lee Chang-Sik
    • Journal of ILASS-Korea
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    • v.2 no.2
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    • pp.43-50
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    • 1997
  • The purpose of this investigation is to carry out, the influence factor on the fuel spray characteristics for improve the engine combustion performance and exhaust omission in direct injection type diesel engine. The fuel properties, fuel spray structure and the shape or the piston surface of diesel engine play an important role of engine combustion process and exhaust emission. In order to obtain the effect of using auxiliary chamber and emulsified fuel on the fuel spray characteristics the experiment un conduct with single cylinder direct injection type diesel engine to examine the engine performance and gas emission. The results of this investigation showed that the increase auxiliary chamber volume and emulsified fuel give an effect on the fuel spray characteristics by reduced the concentration of nitric oxide emission in the combustion chamber. Also it can improve the combustion characteristics such as cylinder pressure, rate of pressure rise and rate of heat release.

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ANALYSIS OF DIRECT INJECTION SI STRATIFIED COMBUSTION IN HYDROGEN LEAN MIXTURE - COMBUSTION PROMOTION AND COOLING LOSS BY HYDROGEN -

  • Shudo, Toshio;Tsuga, Koichiro
    • International Journal of Automotive Technology
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    • v.2 no.3
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    • pp.85-91
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    • 2001
  • Characteristics of methane direct-injection spark-ignition stratified combustion in lean hydrogen mixture were analyzed both in a single cylinder engine and in a constant volume combustion chamber. Combustion pressure and Instantaneous combustion chamber wall temperature during the combustion process were measured with a thin-film thermocouple and used in analyses of combustion and cooling loss. Results in this research show that the premixed hydrogen increases cooling loss to combustion chamber wall while achieving combustion promotion, and the combustion system is effective especially in lean mixture conditions. Analysis of flame propagation was also done with Schlieren photography in the constant volume combustion chamber.

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The Effect of Split Injections on the Stability of Idle Combustion and Emissions Characteristic in a Gasoline Direct Injection Engine (GDI 엔진의 분할 분사가 아이들 연소 안정 및 배출물 특성에 미치는 영향)

  • Roh, H.G.
    • Journal of ILASS-Korea
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    • v.19 no.4
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    • pp.221-226
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    • 2014
  • This paper described the effect of split injections on the stability of combustion and emission characteristics in a direct injection gasoline engine at various operating conditions. In order to investigate the influence of direct injection gasoline engine, the fuel injection timing was varied direct fuel injection at various fuel pressure. The experimental apparatus consisted of GDI engine with 4 cylinder, EC dynamometer, injection control system, and exhaust emissions analyzer. The emission and combustion characteristics were analyzed for the fuel injection timing and fuel injection pressure strategies. It is revealed that CO and HC emissions are dramatically decreased at advanced injection timing. Also, engine performance is increased at increase fuel injection pressure.

A Experimental Study on the Effects of the Impingement-wall on the Spray and Combustion Characteristics of Direct-Injection LPG (충돌벽면이 직분식 LPG의 분무 및 연소 특성에 미치는 영향에 관한 실험 연구)

  • Hwang, Seong-Ill;Chung, Sung-Sik;Yeom, Jeong-Kuk
    • Journal of Power System Engineering
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    • v.19 no.2
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    • pp.49-56
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    • 2015
  • As an alternative fuel that can be used in SI engine, LPG is one of clean fuels with larger H/C ratio compared to gasoline, low $CO_2$ emission, and small amount of pollutants such as sulfur compounds. When LPG is used in spark ignition engine, volumetric efficiency of the engine can be improved and pumping loss can be reduced by performing direct injection into the combustion chamber instead of port fuel injection. LPG-DI engine allows for lean combustion and stratified combustion under low load. In case of stratified combustion, air fuel ratio can be greatly increased compared to theoretic mixture ratio combustion. Improved thermal efficiency of the engine and reduced pumping loss can be expected from stratified combustion. Accordingly in this study, an experimental apparatus for visualization was designed and manufactured to study the combustion process of LPG after injection and ignition, intended to examine ignition probability and combustion characteristics of spark ignition direct injection(SIDI) LPG fuel. Ambient pressure, ambient temperature and fuel injection pressure were found as important variables that affect ignition probability and flame propagation characteristics of LPG-air mixture. Also, it was verified that the injected LPG fuel can be directly ignited by spark plug under appropriate ambient conditions.

Effects of Combustion Characteristics of the Burners for Non-Oxidizing Direct Fired Furnaces on the Oxidization of the Surface of Steel Plate (무산화 직화로 버너의 연소특성이 강재표면의 산화에 미치는 영향)

  • Park, Heung Soo;Riu, Kap Jong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.3
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    • pp.330-341
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    • 1999
  • An experimental study for the two types of burners used in the non-oxidizing direct fired furnaces of the heat treatment process for the cold rolled plate has been carried out to investigate the combustion characteristics and the oxidization of the surface of steel plate. A steep temperature gradient and entrainment of residual oxygen were found near the heating surface in the flame of the nozzle mixing burner which has strong swirl velocity component. It was concluded that the elimination of the residual oxygen and the increase of the temperature of combustion gas on the heating surface are needed to enhance the performance of the burners for application to the non-oxidizing direct fired furnaces.

Modeling of Turbulent Molecular Mixing by the PDF Balance Method for Turbulent Reactive Flows (난류연소 유동장에서의 확률밀도함수 전달방정식을 이용한 난류혼합 모델링)

  • Moon, Hee-Jang
    • Journal of the Korean Society of Combustion
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    • v.2 no.1
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    • pp.39-51
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    • 1997
  • A review of probability density function(PDF) methodology and direct numerical simulation for the purpose of modeling turbulent combustion are presented in this study where particular attention is focused on the modeling problem of turbulent molecular mixing term appearing in PDF transport equation. Existing mixing models results were compared to those evaluated by direct numerical simulation in a turbulent premixed medium with finite rate chemistry in which the initial scalar field is composed of pockets of partially burnt gases to simulate autoignition. Two traditional mixing models, the least mean square estimations(LMSE) and Curl#s model are examined to see their prediction capability as well as their modeling approach. Test calculations report that the stochastically based Curl#s approach, though qualitatively demonstrates some unphysical behaviors, predicts scalar evolutions which are found to be in good agreement with statistical data of direct numerical simulation.

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