• Title/Summary/Keyword: Exhaust

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Effect of Valve Lift and Timing on Internal Exhaust Gas Recirculation and Combustion in DME Homogeneous Charge Compression Ignition Engine (DME 예혼합 압축 착화 엔진에서 밸브 양정과 개폐시기가 내부 배기가스 재순환과 연소에 미치는 영향)

  • Jang, Jin-Young;Bae, Choong-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.4
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    • pp.93-100
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    • 2009
  • Intake/exhaust valve timing and exhaust cam lift were changed to control the internal exhaust gas recirculation (IEGR) and combustion phase of homogeneous charge compression ignition (HCCI) engine. To measure the IEGR rate, in-cylinder gas was sampled during from intake valve close to before ignition start. The lower exhaust cam made shorter valve event than higher exhaust cam and made IEGR increase because of trapping the exhaust gas. IEGR rate was more affected by exhaust valve timing than intake valve timing and increased as exhaust valve timing advanced. In-cylinder pressure was increased near top dead center due to early close of exhaust valve. Ignition timing was more affected by intake valve timing than exhaust valve timing in case of exhaust valve lift 8.4 mm, while ignition timing was affected by both intake and exhaust valve timing in case of exhaust valve 2.5 mm. Burn duration with exhaust valve lift 2.5 mm was longer than other case due to higher IEGR rate. The fuel conversion efficiency with higher exhaust valve lift was higher than that with lower exhaust valve lift. The late exhaust and intake maximum open point (MOP) made the fuel conversion efficiency improve.

Effect of Exhaust Heat Exchanger on Catalytic Converter Temperature in an SI Engine (가솔린 엔진의 배기 열교환기가 촉매 온도에 미치는 영향에 관한 연구)

  • 이석환;배충식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.2
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    • pp.9-16
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    • 2004
  • Close-coupled catalyst (CCC) can reduce the engine cold-start emissions by utilizing the energy in the exhaust gas. However, in case the engine is operated at high engine speed and load condition, the catalytic converter may be damaged and eventually deactivated by thermal aging. Excess fuel is sometimes supplied intentionally to lower the exhaust gas temperature avoiding the thermal aging. This sacrifices the fuel economy and exhaust emissions. This paper describes the results of an exhaust heat exchanger to lower the exhaust gas temperature mainly under high load conditions. The heat exchanger was installed between the exhaust manifold and the inlet of close-coupled catalytic converter. The exhaust heat exchanger successfully decreased the exhaust gas temperature, which eliminated the requirement of fuel enrichment under high load conditions. However, the cooling of the exhaust gas through the heat exchanger may cause the deterioration of exhaust emissions at cold start due to the increment of catalyst light-off time.

Study on the Exhaust Flow Analysis of Unsteady Flow with Various Exhaust Manifolds and Catalyst Geometries (배기계 형상에 따른 비정상 유동에서의 배기매니폴드와 촉매 입구 유동현상 해석)

  • Lee, Jae-Ho;Kim, Dae-Woo;Kwak, Ho-Chul;Park, Sim-Soo
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.217-222
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    • 2004
  • In recent year, as the current and future emission regulations go stringent, the research of exhaust manifold and CCC has become the subject of increasing interest and attention. This study is concerned with the systematic approach to improve catalyst flow uniformity and light-off behavior through the basic understanding of exhaust flow characteristics. Computational approach to the unsteady compressible flow for exhaust manifold of 4-1 type and 4-2-1 type and CCC system of a 4-cylinder DOHC gasoline engine was performed to investigate the flow distribution of exhaust gases. In this study, through calculation, the effects of geometric configuration of exhaust manifold on flow structure and its maldistribution in monolith were mainly investigated to understand the exhaust flow patterns in terms of flow uniformity. Based on the design guidance resulting from this fundamental study, the flow uniformity of 4-2-1 type exhaust manifold demonstrated the more improved exhaust characteristics than that of the 4-1 type one.

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A Study on the Indoor Airflow Pattern by Changing the Location of Mechanical Terminal Unit (실내 급.배기구 위치변화에 따른 실 공기유동에 관한 연구)

  • Choi, Jeong-Min;Cho, Sung-Woo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.21 no.3
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    • pp.193-200
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    • 2009
  • The ventilation system of apartments can be divided by supply and exhaust fan, supply fan and exhaust free and supply free and exhaust fan. Recently, the individual ventilation system and central ventilation system which is combined cooling system with duct system are applied to apartment ventilation system. The airflow pattern is affected by location of supply unit and exhaust unit in indoor. This study is to investigate the proper distance between supply unit and exhaust unit using CFD. As a result of this study, the proper distance between supply unit and exhaust unit could be suggested at the interval of 3 m in supply and exhaust fan system and 2.5 m in supply fan and exhaust free.

A Study on the Information Networks of local Exhaust System of Factories (사업장의 국소배기 설비와 관련된 정보 수집 연결망에 대한 연구)

  • Yoon, Young No;Rhee, Kyoung Yong
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.10 no.2
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    • pp.1-17
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    • 2000
  • We investigated dissatisfaction of elements of local exhaust system, needs for local exhaust system, and information networks for local exhaust system from June 1998 to September 1999 using the questionnaire structured. It contained questions concerning general characteristics of factory and local exhaust system, troubles and dissatisfaction of elements of local exhaust system, and information networks for local exhaust system. The collected data were analyzed by descriptive statistics analysis. Information networks for local exhaust system were analyzed by multidimensional scaling using path distance of network analysis and by graph analysis using Krackplot. Among complaints of local exhaust system, that of duct has show the highest percentage of complaint. In the information network for local exhaust system, Seoul is positioned in the center of network with mediating role.

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The Effects of the Combustion Characteristics on the Exhaust System Volume of the SI Engine in Idling (아이들링 시 배기시스템 용적이 SI 기관의 연소특성에 미치는 영향)

  • Noh, Hyung-Chul;Park, Kyoung-Suk;Son, Sung-Man
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.4
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    • pp.186-192
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    • 2007
  • We research into the exhaust system volume what proving the optimum exhaust performance and combustion characteristics. Many automobile manufactures have developed complex exhaust system for environment regulation and noise reduction. This complex exhaust system provides acoustics silencing and low frequency noise for customers demand. Recently, automobile exhaust system have made the Dual muffler concerning to the noise and vibration reduction. Also it bring the engine performance down by decreasing the back pressure and temperature in the exhaust system. The experiments are carried out different volume of exhaust system. In order to establish the optimized conditions design factors which are taking exhaust system volume, it show how the exhaust performance influence on the engine performance in idling.

ANALYSIS OF GAS-DYNAMIC EFFECTS IN COMPACT EXHAUST SYSTEMS OF SMALL TWO-STROKE ENGINES

  • Galindo, J.;Serrano, J.R.;Climent, H.;Tiseira, A.
    • International Journal of Automotive Technology
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    • v.8 no.4
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    • pp.403-411
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    • 2007
  • This article describes a methodology based on experiments and 1D modeling work related to the exhaust system analysis of a small two-stroke engine. The primary goal of this work was to understand how the design criteria of a compact exhaust system influenced the exhaust port pressure, since its evolution controls not only engine performance but also exhaust emissions. On the experimental side, a fully instrumented 50cc two-stroke engine was used to check the behavior of three different exhaust systems. A problem related to instantaneous pressure measurements in unsteady, hot flow was detected and solved during the study. To build the 1D model of the three exhaust systems, experimental information on the steady flow and the impulse test rigs was obtained under controlled conditions in specific facilities. Accurate comparisons between measured and calculated exhaust port instantaneous pressures were obtained from the following different exhaust system configurations: a straight duct, a tapered pipe and the three compact exhaust systems. The last step in the method used this model to analyze the pressure waves inside the exhaust system and detect the influence of the geometric parameters. The results should lead to improvements in the design process of complex compact exhaust systems in two-stroke engines.

A Study on the Improvement Strategies for Exhaust Performance in Commercial Kitchen Hoods (상업용 주방후드의 배기성능 개선방안에 관한 연구)

  • 박진철
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.5
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    • pp.439-445
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    • 2003
  • The purpose of this study is to suggest the improvement strategies for exhaust performance in composite kitchen hoods. The Exhaust only hood, the 2-way compensating hood and the 3-way compensating hood were selected, and the laboratory experiments were performed to compare the local exhaust efficiency and the indoor temperature distributions according to the variations of the hood type and supply/exhaust air velocity. The results of this study can be summarized as follows. The compensating hood has better performance than exhaust only hood in the aspect of local exhaust efficiency and temperature distribution. The 3-way compensating hood shows the best performance when the supply air velocity is about 2.7 m/s, and the 2-way compensating hood at the supply air velocity of 3.5 w/s. In the same exhaust rate condition, if the exhaust area of the hood is increased and therefore the exhaust velocity is lowered, the supply air velocity is also lowered to get the optimum performance. The optimum exhaust velocity range of the commercial kitchen hood which derived from this study is 0.48 ∼ 0.55 m/s.

THC Reduction through the Improvement of Exhaust System (배기계 형상 개선을 통한 THC 저감에 관한 연구)

  • 김기성;이용호
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.5
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    • pp.111-118
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    • 2000
  • Experimental studies were performed to understand the flow characteristics in the exhaust system and improve the THC emission characteristics by optimizing the flow in the exhaust manifold and CCC in a SI engine. For this purpose, the flow characteristics in the exhaust systems with two types of exhaust manifolds(STD and New Type) were measured by using LDV technique under various engine condition. It was found that the flow characteristics in the New Type exhaust manifold was more desirable in a view point of heat loss reduction from the exhaust gases. The vehicle emission tests showed that the THC emission in the New Type exhaust manifold was decreased by 12%.

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Effect of Recirculated Exhaust Gas on Exhaust Emissions of Boiler with FGR System (FGR 시스템 보일러의 배기 배출물에 미치는 재순환 배기의 영향)

  • Bae, Myung-Whan;Kim, Jung-Min;Kim, Yi-Suk;Cho, Yong-Soo;Choi, Seung-Chul
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.390-395
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    • 2003
  • The effect of recirculated exhaust gas on exhaust emissions under four kinds of nozzle tip with the different fuel consumption rate are experimentally investigated by using an once-through boiler with FGR system. The purpose of this study is to develop the FGR control system for reducing NOx in a boiler. Intake and exhaust oxygen concentrations, and equivalence ratio are applied to discuss the effect of FGR rate on exhaust emissions at various fuel consumption rates. It is found that NOx emissions are decreased, while soot emissions are increased owing to the drop of intake and exhaust oxygen concentrations, and the rise of equivalence ratio as FGR rates are elevated.

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