• Title/Summary/Keyword: EGR(Exhaust Gas Recirculation)

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Finite Element Analysis and Validation for Dimpled Tube Type Intercooler Using Homogenization Method (균질화 기법을 이용한 딤플 튜브형 인터쿨러의 유한요소해석 및 검증)

  • Lee, Hyun-Min;Heo, Seong-Chan;Song, Woo-Jin;Ku, Tae-Wan;Kang, Beom-Soo;Kim, Jeong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.2
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    • pp.153-161
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    • 2009
  • Three-dimensional finite-element methods(FEM) have been used to analyze the thermal stress of an exhaust gas recirculation(EGR) cooler due to thermal and pressure load. Since efficiency and capability of the heat exchanger are mainly dependent on net heat transferring area of the EGR cooler system, the tube inside the system has a numerous dimples on the surface. Thus for finite element analysis, firstly the dimple-typed tube is modeled as a plain element without the dimple, and then the equivalent thermal conductivities and elastic modulus are calculated. This work describes the numerical homogenization procedure of the dimple-typed tube and verifies the equivalent material properties by comparison of a single unit and the actual full model. Finally, the homogenization scheme presented in this study can be efficiently applied to finite element analyses for the thermal stress and deformation behavior of the EGR cooler system with the dimple-typed tube.

A Study on Characteristics of Performance and $NO_x{\cdot}THC$ Emissions in Turbo Intercooler ECU Common-rail Diesel Engines with a Combined Plasma EGR System (플라즈마 EGR 조합시스템 터보 인터쿨러 ECU 커먼레일 디젤기관의 성능 및 $NO_x{\cdot}THC$ 배출물 특성에 관한 연구)

  • Bae, Myung-Whan;Ku, Young-Jin;Lee, Bong-Sub
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.3
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    • pp.10-21
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    • 2006
  • The aim in this study is to develop the combined EGR system with a non-thermal plasma reactor for reducing exhaust emissions and improving fuel economy in turbo intercooler ECU common-rail diesel engines. At the first step, in this paper, the characteristics of performance and $NO_x{\cdot}THC$ emissions under four kinds of engine loads are experimentally investigated by using a four-cycle, four-cylinder, direct injection type, water-cooled turbo intercooler ECU common-rail diesel engine with a combined plasma exhaust gas recirculation(EGR) system operating at three kinds of engine speeds. The EGR system is used to reduce $NO_x$ emissions, and the non-thermal plasma reactor and turbo intercooler system are used to reduce THC emissions. The plasma system is a flat-to-flat type reactor operated by a plasma power supply. The fuel is sprayed by pilot and main injections at the variable injection timing between BTDC $15^{\circ}$ and ATDC $1^{\circ}$ according to experimental conditions. It is found that the specific fuel consumption rate with EGR is increased, but the fuel economy is better than that of mechanical injection type diesel engine as compared with the same output. Results show that $NO_x$ emissions are decreased, but THC emissions are increased, as the EGR rate is elevated. $NO_x$ and THC emissions are also slightly decreased as the applied electrical voltage of the non-thermal plasma reactor is elevated. Thus one can conclude that the influence of EGR in $NO_x$ and THC emissions is larger than that of the non-thermal plasma reactor, but THC emissions are greatly influenced by the non-thermal plasma reactor as the EGR rate is elevated.

Effect of Inlet Temperature and CO2 Concentration in the Fresh Charge on Combustion in a Homogeneous Charge Compression Ignition Engine Fuelled with Dimethyl Ether (Dimethyl Ether 예혼합 압축 착화 엔진에서 흡기중 CO2 농도와 흡기온도 변화가 연소에 미치는 영향)

  • Bae, Choong-Sik;Jang, Jin-Young;Yeom, Ki-Tae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.6 s.261
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    • pp.514-521
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    • 2007
  • This study focused on the effects of the $CO_2$ gas concentration in fresh charge and induction air temperature on the combustion characteristics of homogeneous charge compression ignition with dimethyl ether (DME) fuel, which was injected at the intake port. Because of adding $CO_2$ in fresh charge, start of auto-ignition was retarded and bum duration became longer. Indicated combustion efficiency and exhaust gas emission were found to be worse due to the incomplete combustion. Partial burn was observed at the high concentration of $CO_2$ in fresh charge with low temperature of induction air. However, indicated thermal efficiency was improved due to increased expansion work by late ignition and prolonged bum duration. Start of auto-ignition timing was advanced with negligible change of burn duration, as induction air temperature increased. Burn duration was mainly affected by oxygen mole concentration in induction mixture. Bum duration was increased, as oxygen mole concentration was decreased.

Reduction of Exhaust Emissions Using Various Injector Configurations in Low Temperature Diesel Combustion (분사기 형상 변경을 통한 저온 디젤 연소의 배기 배출물 저감)

  • Jung, Yong-Jin;Jang, Jin-Young;Park, Jung-Seo;Bae, Choong-Sik;Kim, Duk-Sang
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.4
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    • pp.16-23
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    • 2011
  • Low temperature combustion is one of the advanced combustion technology in an internal combustion engine to reduce soot and nitrogen oxides simultaneously. In present experiment three kinds of injector were used to investigate the influence of injection angle and number of nozzle holes on the low temperature combustion in a heavy duty diesel engine. Low temperature diesel combustion is realized from the exhaust gas recirculation rate of 60%. Indicated mean effective pressure of low temperature combustion corresponds to the 70% level of conventional diesel engine combustion. Reduction of hydrocarbon and carbon monoxide, which are produced in low temperature combustion because of the low combustion temperature and a deficit of oxygen, was achieved by using various injector configuration. The result of experiment with $100^{\circ}$ injection angle and 8 holes showed that reductions in hydrocarbon and carbon monoxide could be achieved 58% and 27% respectively maintaining the 7% increased indicated mean effective pressure in low temperature diesel combustion compared with conventional injector.

A Modeling of Flame Initiation and Its Development in SI Engines (SI 기관에서 초기 화염의 생성 및 성장에 대한 모델링)

  • Song, Jeonghoon;Sunwoo, Myoungho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.2
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    • pp.288-298
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    • 1999
  • In spark ignited engines, the electrical spark not only sets the time for the onset of combustion but also is able to greatly influence the character of the initial flame growth and the subsequent combustion, and thereby can influence engine performance. The relative importance of the ignition energy is particularly high under lean or high residual gas or exhaust gas recirculation (EGR). In this study, a modeling of flame Initiation and its development is proposed. Submodels consist in representing of cylinder pressure and temperature, heat transfer to cylinder wall, and flame kernel heat transfer to ambient air and to spark plug electrodes. The breakdown process and the subsequent electrical power input initially control the kernel growth while intermediate growth is mainly dominated by diffusion or conduction. Then, the flame propagates by the chemical energy, and laminar and turbulent flame velocity.

Combustion and Emission Characteristics of Biodiesel Blended Fuel by EGR Rate in a 4-cylinder CRDI Diesel Engine (4실린더 커먼레일 디젤엔진에서 바이오디젤 혼합연료와 EGR율에 따른 연소 및 배기특성)

  • Jeong, Kyu-Soo;Lee, Dong-Gon;Youn, In-Mo;Roh, Hyun-Gu;Park, Sung-Wook;Lee, Chang-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.4
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    • pp.130-136
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    • 2011
  • This study describes the effect of EGR rate on the combustion and emissions characteristics of a four cylinder CRDI diesel engine using biodiesel (soybean oil) blended diesel fuel. The test fuel is composed of 30% biodiesel and 70% ULSD (ultra low sulfur diesel) by volumetric ratio. The experiment of engine emissions and performance characteristics were performed under the various EGR rates. The experimental results showed that ignition delay was extended, the maximum combustion pressure and heat release gradually were decreased with increasing EGR rate. Comparing biodiesel blended fuel to ULSD, the injection quantity of biodiesel blended fuel was further increased than ULSD. The emission results showed that $NO_x$ emission of biodiesel blended fuel becomes higher according to the increase of EGR rate. However, in the case of biodiesel blended fuel, HC, CO and soot emissions were decreased compared to ULSD.

Nonlinear Static Model-based Feedforward Control Algorithm for the EGR and VGT Systems of Passenger Car Diesel Engines (승용디젤엔진의 EGR, VGT 시스템을 위한 비선형 정적 모델 기반 피드포워드 제어 알고리즘 설계)

  • Park, Inseok;Park, Yeongseop;Hong, Seungwoo;Chung, Jaesung;Sohn, Jeongwon;Sunwoo, Myoungho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.6
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    • pp.135-146
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    • 2013
  • This paper presents a feedforward control algorithm for the EGR and VGT systems of passenger car diesel engines. The air-to-fuel ratio and boost pressure are selected as control indicators and the positions of EGR valve and VGT vane are used as control inputs of the EGR and VGT controller. In order to compensate the non-linearity and coupled dynamics of the EGR and VGT systems, we have proposed a non-linear model-based feedforward control algorithm which is obtained from static model inversion approach. It is observed that the average modeling errors of the feedforward algorithm is about 2% using stationary engine experiment data of 225 operating conditions. Using a feedback controller including proportional-integral, the modeling error is compensated. Furthermore, it is validated that the proposed feedforward algorithm generates physically acceptable trajectories of the actuator and successfully tracks the desired values through engine experiments.

A Study on Effect of a Combined Plasma EGR System upon Soot CO and $CO_2$ Emissions in Turbo Intercooler Common-rail Diesel Engines (터보 인터쿨러 커먼레일 디젤기관의 매연, CO 및 $CO_2$ 배출물에 미치는 플라즈마 EGR 조합시스템의 영향에 관한 연구)

  • Bae, Myung-Whan;Ku, Young-Jin;Lee, Bong-Sub;Youn, Il-Joong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.4
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    • pp.1-11
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    • 2006
  • The aim in this study is to develop the combined EGR system with a non-thermal plasma reactor for reducing exhaust emissions and improving fuel economy in turbo intercooler ECU common-rail diesel engines. In this study, the characteristics of soot, CO and $CO_2$ emissions under four kinds of engine loads are experimentally investigated by using a four-cycle, four-cylinder, direct injection type, water-cooled turbo intercooler ECU common-rail diesel engine with a combined plasma exhaust gas recirculation(EGR) system operating at three kinds of engine speeds. The EGR and non-thermal plasma reactor system are used to reduce $NO_x$ emissions, and the non-thermal plasma reactor and turbo intercooler system are used to reduce soot and THC emissions. The plasma system is a flat-to-flat type reactor operated by a plasma power supply. The fuel is sprayed by pilot and main injections at the variable injection timing between BTDC $15^{\circ}$ and ATDC $1^{\circ}$ according to experimental conditions. It is found that soot emissions with increasing EGR rate are increased, but are decreased as the applied electrical voltage of the non-thermal plasma reactor is elevated at the same engine speed and load. Results also show that CO and $CO_2$ emissions are increased as EGR rate is elevated, and CO emissions are increased, but $CO_2$ emissions are decreased as the applied electrical voltage of the non-thermal plasma reactor is elevated at the same engine speed and load.

Internal modifications to reduce pollutant emissions from marine engines. A numerical approach

  • Lamas, M.I.;Rodriguez, C.G.;Rodriguez, J.D.;Telmo, J.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.5 no.4
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    • pp.493-501
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    • 2013
  • Taking into account the increasingly stringent legislation on emissions from marine engines, this work aims to analyze several internal engine modifications to reduce $NO_x$ (nitrogen oxides) and other pollutants. To this end, a numerical model was employed to simulate the operation cycle and characterize the exhaust gas composition. After a preliminary validation process was carried out using experimental data from a four-stroke, medium-speed marine engine, the numerical model was employed to study the influence of several internal modifications, such as water addition from 0 to 100% water to fuel ratios, exhaust gas recirculation from 0 to 100% EGR rates, modification of the overlap timing from 60 to $120^{\circ}$, modification of the intake valve closing from 510 to $570^{\circ}$, and modification of the cooling water temperature from 70 to $90^{\circ}C$. $NO_x$ was reduced by nearly 100%. As expected, it was found that, by lowering the combustion temperature, there is a notable reduction in $NO_x$, but an increase in CO (carbon monoxide), HC (hydrocarbons) and consumption.

Evaluation of EGR applicability for NOx reduction in lean-burn LPG direct injection engine (초희박 LPG 직접분사식 엔진에서 질소산화물 저감을 위한 배기재순환 적용성 평가)

  • Park, Cheolwoong;Cho, Seehyeon;Kim, Taeyoung;Cho, Gyubaek;Lee, Janghee
    • Journal of the Korean Institute of Gas
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    • v.19 no.4
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    • pp.22-28
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    • 2015
  • In order to keep the competitiveness of LPG fuel for transportation fuel, the difference in fuel consumption with gasoline and cost for an aftertreatment system should be reduced with continuous development of technology for LPG engine. In the present study, spray-guided type direct injection combustion system, whose configuration is composed of direct injector in the vicinity of spark plug, was employed to realize stable lean combustion. A certain level of nitrogen oxides($NO_x$) emits due to a locally rich mixture regions in the stratified mixture. With the application of EGR system for the reduction of $NO_x$, 15% of $NO_x$ reduction was achieved whereas fuel consumption and hydrocarbon emission increased. By the application of EGR, the combustion speed reduced especially appeared at initial flame development period and peak heat release rates and increasing rates for heat release rate decreased as EGR rate increased due to the dilution effect of intake air.