• 제목/요약/키워드: Thermal NOx

검색결과 362건 처리시간 0.032초

동축류 확산화염에서 질소첨가가 Soot발생에 미치는 영향 (Dilution and Thermal Effects of N2 Addition on Soot Formation in Co-flow Diffusion Flame)

  • 엄재호;이종호;전충환;장영준
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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    • pp.185-191
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    • 2002
  • The influence of N2 addition on soot formation, flame temperature and NOx emissions is investigated experimentally with methane fuel co-flow diffusion flames. The motivation of the present investigation is the differences in NOx reduction reported between fuel-side and oxidizer-side introduction of N2. To determine the influence of dilution alone, fuel was diluted with nitrogen while keeping the adiabatic flame temperature fixed by changing the temperature of the reactants. And to see the thermal effect only, air was supplied at different temperature without N2 addition. N2 addition into fuel side suppressed the soot formation than the case of oxidizer-side, while flame temperature enhanced the soot formation almost linearly. These results reveals the relative influences of the thermal, concentration effects of N2 additives on soot formation In accordance with experimental study, numerical simulation using CHEMKIN code was carried out to compare the temperature results with those acquired by CARS measurement, and we could find that there is good agreement between those results. Emission test revealed that NOx emissions were affected by not only flame temperature but also N2 addition.

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Ni, Ru-ZSM-5를 첨가한 NSR 촉매의 NOx 정화 특성 (Characteristics of NOx Reduction on NSR(NOx Storage and Reduction) Catalyst Supported by Ni, Ru-ZSM-5 Additives)

  • 최병철;이춘희;정종우
    • 한국자동차공학회논문집
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    • 제15권5호
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    • pp.105-111
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    • 2007
  • In this study, we investigated the conversion performance of de-NOx catalyst for lean-burn natural gas engine. As a de-NOx catalyst, NOx storage reduction catalyst was composed of Pt, Pd and Rh with washcoat including Ba and Ni, Ru-ZSM-5. Ni, Ru-ZSM-5, which was regarded as a NOx direct decomposition catalyst, was made up of ion exchanged ZSM-5 by 5wt.% Ni or Ru. The performance of de-NOx catalyst was evaluated by NOx storage capacity and catalytic reduction in air/fuel, $\lambda=1.6$. The catalytic reaction was also observed when the added fuel was supplied to fuel rich atmosphere by fuel spike period of 5 seconds. The NOx conversion of the catalysts with Ni-ZSM-5 or Ru-ZSM-5 was mainly caused by the effect of NOx adsorption of Ba rather than the catalytic reduction of Ni, Ru-ZSM-5. Ni, Ru-ZSM-5 catalysts can not use for the NSR catalyst because they have quick process in thermal deactivation.

Thermal Evaporation법에 의해 제조된 WO3 박막과 NiO-WO3박막의 전기적 특성에 관한 연구 (A Study On the Electrical Characteristic of WO3 and NiO-WO3 Thin Films Prepared by Thermal Evaporation)

  • 나은영;나동명;박진성
    • 전기화학회지
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    • 제8권1호
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    • pp.32-36
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    • 2005
  • 본 연구는 $WO_3$ 박막과 $NiO-WO_3$ 박막을 고진공 저항가열식 thermal evaporation 법으로 (100) n형의 실리콘 단결정 기판 위에 증착시켰고, 막의 결정성 증진을 위하여 공기 중 $500^{\circ}C$에서 30분 동안 열처리하였다. 박막의 결정성 및 결정구조를 분석하기 위해서 X선 회절분석기를 사용하였고, 표면 및 단면 관찰을 위해서는 주사전자현미경을 이용하였다. 그리고 화학 조성 결합에너지는 XPS를 이용하였다. 순수 $WO_3$ 박막의 결정 크기는 $500^{\circ}C$에서 30분 동안 공기중 열처리에 의해서 $0.6{\mu}m$로 성장하였고 $WO_3$ 박막의 두께가 증가할수록 거의 변화 없이 일정하였다. 반면, NiO가 첨가된 $WO_3$ 박막 두께별 결정크기는 각각 $0.12{\mu}m,\;0.28{\mu}m,\;0.32{\mu}m$$0.43{\mu}m$로 순수 $WO_3$ 박막에 비해 치밀한 표면을 형성하였고, 최대 5배정도 성장이 억제되었다. 가스감도 측정은 대기 중에서의 센서 저항 값을 기준으로 측정가스 저항 값의 비율 $(R_{NOx}/R_{air})$로 가스감도를 나타내었다. 전기적 성질은 MFC로 NOx가스 5ppm을 일정히 유지시켰고, Multimeter로 계측하여 컴퓨터에 자동 계측되는 시스템을 사용하였다. 순수 $WO_3$박막보다는 $NiO-WO_3$ 박막이 우수한 NOx 감도특성을 보였고 센서의 작동온도는 $250^{\circ}C$에서 우수한 감도를 나타내었다.

이중원추형 모형연소기에서 압력과 공기비에 따른 NOx 배출특성 (Effect of Pressure and Stoichiometric Air Ratio on NOx Emissions in Gas-Turbine Dump Combustor with Double Cone Burner)

  • 남동현;남현수;한동식;김규보;조승완;김한석;전충환
    • 대한기계학회논문집B
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    • 제36권3호
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    • pp.251-257
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    • 2012
  • 본 연구에서는 이중원추형 버너가 장착된 고압연소기를 이용하여 입구공기온도, 공기비 그리고 연소실 압력조건에 따른 NOx 배출 특성을 실험적으로 조사하였다. 배기가스 온도와 NOx 배출량은 동일한 연소실 끝단지점에서 측정되었다. NOx 배출량은 공기비가 증가함에 따라 감소하는 경향을 나타내었으며, 입구공기 온도와 연소실의 압력이 높아질수록 증가하는 경향을 나타내었다. 특히 입구공기 온도의 증가는 희박 영역에서 가연한계를 증가시켜 높은 단열화염 온도를 가짐에도 불고하고 저감된 NOx 배출 수준을 얻을 수 있었다. 연소실 압력이 증가할수록 Thermal NOx의 영향을 받는 영역에서의 NOx 배출은 큰 폭의 상승을 보였으나, 공기비가 1.8이상인 영역에서는 적은 연료량으로 인하여 적은 상승폭을 나타내었다.

분류 및 대향류 확산 소화염의 구조 및 NOx 생성특성 비교 검토 (A Study on Structures and NOx Formation Characteristics in Coflow and Counterflow Diffusion Flamelet)

  • 오창보;김종수;이창언;이기만
    • 한국연소학회지
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    • 제3권2호
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    • pp.29-40
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    • 1998
  • Flame structures and NOx formation characteristics in the flame lets of coflow and counterflow diffusion flame are numerically studied. Calculations were carried out twice with the $C_2-Full$ and $C_2-Thermal$ Mechanism for each flame. Mixture fractions and scalar dissipation rates are used as the parameters to compare the flame let structures and NOx formation characteristics quantitatively. It was found that there is a similarity in flame temperature and stable species profiles except radical profiles between two flamelets. And there are some differences in NOx concentration and production rates. These results imply that the flow effects must be considered in calculations for NOx formation of turbulent flames using Laminar Flamelet Model.

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회전 아크 적용 플라즈마 저 NOx 버너 연소특성 (Characteristics of Low NOx Plasma Burner Incorporating with Rotating Arc Plasma)

  • 김관태;강희석;이대훈;송영훈;박재언
    • 한국수소및신에너지학회논문집
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    • 제22권6호
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    • pp.934-941
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    • 2011
  • Characteristics of low NOx burner is investigated. Low NOx burner introduced in this paper adopts two staged combustion with plasma burner for the 1st stage combustion. Extensive parametric tests were done to figure out the effect of burner stoichiometry, staged thermal load, electric power for plasma generation. Overall NOx production by burner shows effective reduction by adopting plasma staged burner. and the aspects depends on the fuel stoichiometry of 1st stage burner or operating condition of plasma burner. It is promising to use plasma burner as an alternative tools of low NOx burner technology.

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.

Non-thermal Plasma Discharge를 이용한 $NO_x$ 제거에 관한 연구 (A Study on the removal of $NO_x$ by using Non-thermal Plasma Discharge)

  • 안정언;이석현;정용원
    • 한국대기환경학회:학술대회논문집
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    • 한국대기환경학회 2001년도 추계학술대회 논문집
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    • pp.419-420
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    • 2001
  • 최근 산업설비 및 기타 시설에서 배출되는 유해가스의 배출허용 기준이 계속 강화되고 있으며 그 중에서도 NOx는 SOx와 함께 대기오염의 주된 원인으로 작용하고 있다. 국내에서도 이들 유해가스를 제거하기 위한 플라즈마 적용기술이 활발히 연구되었으며, 일부 기술은 상용화 단계에 있다. NOx 제거에 있어서 펄스 코로나 방전에 의한 전자의 생성은 유입되는 가스 및 공기에 충돌하여 반응성이 큰 다량의 이온, 원자 및 radical(N, O, OH, $O_3$등)을 생성한다. (중략)

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부분적 예혼합 LPG/공기 화염에서 음향자진이 NOx 배출에 미치는 영향 (Effects of Acoustic Excitation on NOx Emission in Partially Premixed LPG/Air Flames)

  • 장준영;박성호;김태권
    • 한국자동차공학회논문집
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    • 제10권3호
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    • pp.77-84
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    • 2002
  • Measurements of NO and NOx emission of laminar partially premixed LPG/air flames with and without acoustic excitation are reported. The NOx emission at the tailpipe of a combustion chamber is determined by chemiluminescent analyser. The NOx measurements are taken in flames with several different center tube equivalance ratio( ø$\sub$o/), and overall equivalace ratio(ø$\sub$o/) for a fixed fuel flowrate. The NOx emission decrease to reach a minimum value at an optimum ø$\sub$c/ 2. Theø$\sub$c/ 2 flame gives a compromise of thermal NO and prompt NO mechanism. In the case of excitation. the visual shape of the flame is changed from laminar flame to turbulent-like flame. With increasing levels of excitation amplitude, an optimum value of the NO and NOx emission exists. A shorter flame caused by the enhanced upstream mixing due to acoustic excitation results in the reduction of NO and NOx emission in the present flames. The reduction of flame length affects the shorter residence time of center tube mixture, and significantly influences the NOx reduction.

고온 배기가스의 산소농도가 비예혼합화염의 NOx 발생에 미치는 영향 (Effects of Oxygen Concentration on the NOx Emission of Non-premixed Flame in Hot Exhaust Gas)

  • 손화승;김호영
    • 대한기계학회논문집B
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    • 제26권6호
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    • pp.833-841
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    • 2002
  • The present study examined the possibility of NOx reduction in the high temperature industrial furnaces, duct burner of gas turbine cogeneration and two-stage gas turbine combustor. The experimental study was carried out for the non-premixed flame of second stage combustor with the variations of oxygen concentration in the hot exhaust gas of first stage combustor. It also examined the flammability range, temperature and NOx, $CO_2$, $O_2$formation in the combustor with respect to oxygen concentration in which the fuel(natural gas) is supplying into the hot exhaust gas. The results show that the inner temperature of flame reaches 1,20$0^{\circ}C$ at EGR $O_2$23% and that 15ppm of NOx at EGR $O_2$15.5% increases up to 60ppm at EGR $O_2$23%. It is believed that Fenimore's prompt NOx mechanism is more influential on the NOx formation than Zeldovich's thermal NOx mechanism does.