• Title/Summary/Keyword: Nitrogen oxides (NOx)

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Dielectric packed-bed 플라즈마 반응기를 사용한 NOx 제거 특성 (NOx removal characteristics by the dielectric packed-bed plasma reactor)

  • 김응복;김동욱;정영식
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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    • pp.1087-1089
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    • 1999
  • This paper presents the removal characteristics of nitrogen oxides (NOx) by the dielectric ($Al_{2}O_{3}$) packed-bed plasma reactor. Reactor packed with 5-mm diameter $Al_{2}O_{3}$ beads, and was designed to remove NOx at atmospheric pressures from the moving pollution source such as diesel automobile. The experiments were conducted for applied voltages from 5 to 10kV, flue gas rate from 2 to 5L/min, and frequency from 0.5 to 2kHz. The NOx removal efficiency significantly increased with increasing applied voltage. Especially removal rate significantly increased with increasing frequency. However, in this experiment discharge power was relatively high.

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지연분사급속연소방식 예혼합연소 기술에 의한 NOx, PM의 동시저감 (Simultaneous NOx, PM Reduction by the Late Injection & Fast Combustion Type Premixed Combustion Technology)

  • 김장헌;최인용;김창일
    • 한국자동차공학회논문집
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    • 제12권4호
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    • pp.31-35
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    • 2004
  • A new combustion strategy called LIFC(Late Injection & Fast Combustion) was developed for simultaneous reduction of particulate matter(PM) and nitrogen oxides(NOx) in exhaust emission of diesel engines, In this study, effects of injection timing and injection pressure under relatively high EGR rate were investigated. The experiments were conducted in a conventional engine over a range of commercial engine speed. The test engine could be operated in LIFC up to 2000rpm / bmep 5 bar condition with significant reduction of NOx and PM. The experimental results showed potential for the mechanism of the simultaneous reduction of NOx and PM from HSDI diesel engines.

디젤기관의 대체연료로서 DEE의 연소 특성에 관한 연구 (A Study on the Combustion Characteristics of DEE as an Alternative Fuel in Diesel Engine)

  • 유경현;최준혁;오영택
    • 한국자동차공학회논문집
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    • 제9권6호
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    • pp.47-56
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    • 2001
  • Nitrogen oxides(NOx) and smoke emissions of diesel engine are regarded as a source of air pollution, and there is a global trend to enforce more stringent regulations on these exhaust gas emissions. However, the trade-off relation of NOx and smoke is a main obstacle to reduce both of them simultaneously. In this paper, experiments were conducted with an oxygenated fuel(diethyl ether) as an effective way to improve the trade-off relation of NOx and smoke. Exhaust emissions of diesel fuels with DEE were influenced by the additive content of DEE and the injection timing. Especially, DEE effected more at the high engine speed and load than at the low engine speed and load. Diesel fuel blended with DEE 10% was a desirable blend for the simultaneous reduction of NOx and smoke.

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양쪽 출구가 트인 배기가스 재순환 버너의 연소 유동 특성에 관한 연구 (A Study of the Combustion Flow Characteristics of a Exhaust Gas Recirculation Burner with Both Outlets Opening)

  • 하지수
    • 한국산학기술학회논문지
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    • 제19권6호
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    • pp.696-701
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    • 2018
  • 연소 반응 시 발생하는 질소산화물은 산성비와 미세먼지 발생에 많은 영향을 미치는 물질이다. 이에 대한 저감 방법으로 고비용의 탈질설비 대신 지연연소 등의 방법에 대한 연구가 많이 이루어지고 있다. 이러한 연구들 중에 적은 양의 공기로 많은 양의 배기가스를 재순환 할 수 있는 코안다 노즐을 이용한 배기가스 재순환 연소에 대한 연구가 최근에 이루어지고 있다. 본 연구에서는 배기가스 재순환 배관에 코안다 노즐을 사용하여 배기가스를 재순환하는 재순환 버너의 양쪽 출구가 트인 형상에 대하여 전산유체해석을 통해 연구를 수행하였으며 연소 유동의 압력, 유선, 온도, 연소 반응 속도와 질소산화물의 분포 특성을 살펴보았다. 배기가스를 재순환하여 연소용 공기와 혼합된 기체가 원통의 접선방향으로 유입되어 연료노즐 출구 부근에서 압력이 낮은 영역이 존재하고 이에 따라 원통 버너의 중심부근에는 버너의 가운데 부분으로 역류가 형성되며 가장자리 부분으로 배기가스가 배출되는 것을 확인하였다. 배기가스가 유입되는 부분이 버너의 오른쪽에 있어서 버너의 오른쪽으로 연소반응이 일어나며 상대적으로 온도분포와 NOx 분포가 높게 나타났다. 연소용 공기비를 1.0에서 1.8까지 변화하여 NOx 생성을 관찰한 결과, 공기비가 1.0에서 1.5까지는 평균 NOx 생성이 감소하다가 공기비가 1.8일 때 급격히 증가하는데 이는 NOx 생성 반응은 온도의 지수승에 비례하게 되는데 공기비가 1.5이상이 되면서 온도의 영향을 많이 받아서 NOx 생성 반응이 오른쪽 영역에서 급격히 증가하는 것으로 판단된다.

적층형 EGR Cooler의 Pitch 길이 변화가 열교환 특성에 미치는 영향 (Effects of Pitch Length of Stack-type EGR Cooler on Heat Exchange Characteristics in a Diesel Engine)

  • 황세준;김민철;장상훈;김형만
    • 한국자동차공학회논문집
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    • 제18권2호
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    • pp.135-140
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    • 2010
  • An important goal in diesel engine research is the development of a means to reduce the emissions of nitrogen oxides (NOX). The use of a cooled exhaust gas recirculation (EGR) system is one of the most effective techniques currently available for reducing nitrogen oxides. Since Particular Matter (PM) fouling reduces the efficiency of an EGR cooler, a trade-off exists between the amount of NOX and PM emissions, especially at high engine loads. In the present study, engine dynamometer experiments have been performed to investigate the heat exchange characteristics of the stack-type EGR coolers with wave fin pitches of 3.6 and 4.6 mm. The results show that the heat exchange effectiveness is decreased as surface area decrease with pitch of 4.6 mm due to PM fouling. As surface area increase at pitch of 3.6 mm, super-cooling happens in the recirculated exhaust gas.

2단분사법에 따른 예혼합압축착화엔진의 연소 및 배기특성 (Effects of Two-Stage Injection on Combustion and Exhaust Emission Characteristics in a HCCI Engine)

  • 국상훈;박철웅;최욱;배충식
    • 한국자동차공학회논문집
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    • 제12권5호
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    • pp.32-39
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    • 2004
  • HCCI (Homogeneous Charge Compression Ignition) combustion has a great advantage in reducing NOx (Nitrogen Oxides) and PM (Particulate Matter) by lowering the combustion temperature due to spontaneous ignitions at multiple sites in a very lean combustible mixture. However, it is difficult to make a diesel-fuelled HCCI possible because of a poor vaporability of the fuel. To resolve this problem, the two-stage injection strategy was introduced to promote the ignition of the extremely early injected fuel. The compression ratio and air-fuel ratio were found to affect not only the ignition, but also control the combustion phase without a need for the intake-heating or EGR (Exhaust Gas Recirculation). The ignition timing could be controlled even at a higher compression ratio with increased IMEP (Indicated Mean Effective Pressure). The NOx (Nitrogen Oxides) emission level could be reduced by more than 90 % compared with that in a conventional DI (Direct Injection) diesel combustion mode, but the increase of PM and HC (Hydrocarbon) emissions due to over-penetration of spray still needs to be resolved.

선박 기인 대기오염물질 현황 및 저감 기술 소개 (Current Status of Air Pollutants from Ships and Reduction Technologies)

  • 박준성;함승호;강다영;박희연;박종관
    • 대한조선학회논문집
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    • 제61권2호
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    • pp.135-142
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    • 2024
  • There is a lot of concern around the world about air pollution from ships. The majority of air pollution from ships comes from fuel combustion. The combustion process produces various air pollutants such as carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), sulfur oxides (SOx), and particulate matter (PM), each of which has adverse effects on people and is a major environmental problem. To prevent this, the International Maritime Organization (IMO) has strengthened the regulation of pollutant emissions through the Convention for the Prevention of Marine Pollution. This paper discusses the types of air pollutants emitted by ships, their current status, and the latest technologies to reduce emissions of NOx and SOx.

디젤엔진에서 수소 환원제 공급 조건에 따른 LNT 촉매 성능 (Performance of LNT Catalyst according to the Supply Condition of Hydrogen Reductants for Diesel Engine)

  • 박철웅;김창기;최영;강건용
    • 한국자동차공학회논문집
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    • 제17권3호
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    • pp.142-148
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    • 2009
  • The direct injection(DI) diesel engine has become a prime candidate for future transportation needs because of its high thermal efficiency. However, nitrogen oxides(NOx) increase in the local high temperature regions and particulate matter (PM) increases in the diffusion flame region within diesel combustion. Therefore, the demand for developing a suitable after treatment device has been increased. NOx absorbing catalysts are based on the concept of NOx storage and release making it possible to reduce NOx emission in net oxidizing gas conditions. This De-NOx system, called the LNT(Lean NOx Trap) catalyst, absorbs NOx in lean exhaust gas conditions and release it in rich conditions. This technology can give high NOx conversion efficiency, but the right amount of reducing agent should be supplied into the catalytic converter at the right time. In this research, a performance characteristics of LNT with a hydrogen enriched gas as a reductant was examined and strategies of controlling the injection and rich exhaust gas condition were studied. The NOx reduction efficiency is closely connected to the injection timing and duration of reductant. LNT can reduce NOx efficiently with only 1 % fuel penalty.

대향류 화염에서 FGR이 적용된 저공해 연소의 수치적 해석: Part I. 저 NOx 연소특성 (Numerical Investigation of Low-pollution Combustion with applying Flue Gas Recirculation in Counterflow Flames: Part I. Combustion Characteristics of Low NOx)

  • 조서희;이기만
    • 한국가스학회지
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    • 제23권6호
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    • pp.8-16
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    • 2019
  • 저공해 연소를 위한 방법 중 하나인 배기가스 재순환(flue gas recirculation, 이하 FGR)은 질소산화물 저감에 효과적인 연소 기법이다. 이를 메탄/공기 대향류 예혼합화염에 적용하여 화염의 특성변화와 NOx 생성 기구를 파악하기 위한 수치해석을 진행하였다. 신장률에 따라 배출되는 생성물들의 몰분율이 달라진다는 점을 고려하여 재순환율은 생성물을 기준으로 정의되었으며, 실제 연소 시스템을 반영하기 위해 주요 생성물인 CO2, H2O, O2 그리고 N2를 희석제로써 재순환하였다. FGR 기법이 적용됨에 따라 특정한 신장률 조건에서 최대화염 온도의 전환점이 발견되었다. 또한, 재순환율이 증가함에 따라 온도와 NO의 경향이 달리 나타났으며, 이를 파악하고자 NO 반응을 열적 NO와 Fenimore NO로 구분하여 분석하였다.

저 NOx2단 선회 분무식 노즐 개발 및 실기적용 연구 (A Study for Development and Application of a Low NOx 2-staged Swirl Atomizer)

  • 송시홍;김혁필;안상택;이익형
    • 대한기계학회논문집B
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    • 제25권12호
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    • pp.1793-1801
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    • 2001
  • A study of low NOx atomizer was carried out to reduce nitrogen oxides(NOx) in a liquid fuel burner flame. The basic concept of NOx reduction in this atomizer is the fuel 2-staging combustion which is generated by a single atomizer forming two different stoichiometric flames. Two orifices swirl atomizer was selected and modified to realize this concept, and it was tested to obtain the design process of low NOx atomizer. These experiments were achieved to find out the relationship between the injection pressures and the flow rate, spray angle and drop size of swirl atomizer as well as to confirm the NOx reduction concept in real plant(power boiler). In comparison between experimental and theoretical results, the correct discharge coefficient and spray angle were obtained. In real burning test, NOx reduction rate was reached to above 27% of the case using conventional swirl atomizer.