와류 발생기를 장착한 가스터빈 연소기에서 연료/공기 혼합 및 NOx 배출 특성에 관한 수치적 연구

김구(Gu Kim),이영덕(Young Duk Lee),손채훈(Chae Hoon Sohn) 한국연소학회 2013 한국연소학회지 Vol.18 No.3

가스터빈용 희박 예혼합 연소기 내부에 와류 발생기(vortex generator)를 장착하여 그에 따른 연료/공기혼합 및 NOx 배출 특성 변화를 조사하였다. 이를 위해 수치해석적 방법을 채택하여 연소기내 유동특성, 연료/공기 혼합도, 배기가스(NOx), 화염형상을 분석하였다. 와류 발생기를 장착한 경우, 연소기 내부에서 와류 발생기에 의한 나사산 형상으로 인해 와류가 형성되며 이는 연소기 전면부까지 유지되었다. 또한 연소기 내부 면적 차로 인해 압력섭동이 발생하였다. 이와 더불어 연소기 전면부 기준 상류지역의 연료와 공기의 혼합도가 증가됨으로서 연료 과농지역이 감소하게 되며 이로 인해 전반적인 NOx 발생량의 감소 효과를 볼 수 있었다. 화염 형상의 변화로부터 와류 발생기의 영향으로 선회수는 다소 감소할 것으로 예상되며, 이는 와류 발생기로 인한 유속의 반복적 증감에 의한 결과라고 판단된다.

탈휘발 예측 코드를 활용한 탈휘발 및 촤반응 모델 평가

정대로(Daero Joung),한가람(Karam Han),허강열(Kang Y. Huh),박호영(Hoyoung Park) 한국연소학회 2012 한국연소학회지 Vol.17 No.2

In this study, pre-processor code based on structural behavior of coal is applied to predict yields, pyrolysis rate and compositions of volatile and char. These parameters are used in the devolatilization and char burnout submodels as user-defined functions of commercial CFD code. The predicted characteristics of these sub-models are compared with those employing the conventional model based on experiment and validated against the measurement of a 2.1 MW swirling pulverized coal flame in a semi-industrial scale furnace. And the influence of the turbulence-chemistry interaction on pulverized coal combustion is analyzed.

대향류 확산화염에서의 매연 특성에 관한 연구

강경태,정석호 한국연소학회 1990 한국연소학회 학술강연회 초록집 Vol.- No.-

상호작용하는 대향류 메탄-수소 부분예혼합화염의 CO 배출특성

박지웅(Ji-Woong Park),오창보(Chang Bo Oh),김태형(Tae-Hyung Kim),박종호(Jongho Park) 한국연소학회 2012 한국연소학회지 Vol.17 No.3

The CO emission characteristics of interacting hydrogen and methane partially premixed flames were numerically investigated. A counterflow geometry was introduced to establish interacting two partially premixed flames. An one-dimensional OPPDIF code was used to simulate the interacting flames. The GRI-v3.0 was used to calculate the chemical reactions. Emission index for CO(EICO) was evaluated to quantify the CO emitted from the interacting flames. The global strain rate and equivalence ratios for each flame(ΦCH₄ and ΦH₂) were used as parameters to control the extent of interaction between two partially premixed flames. When ΦCH₄ was kept to stoichiometric condition and ΦH₂ was at rich condition, unburned H₂ species of hydrogen flame was transported to the methane flame and affected reactions related with CO formation. When ΦCH₄ increased from a stoichiometry to rich condition while ΦH₂ was kept to stoichiometric condition, EICO increased initially, had a peak value at ΦCH₄ = 1.5 and decreased gradually. This could be elucidated with an analysis for the elementary reactions related with CO formation.

정적 구형 용기 내 연소 압력을 이용한 층류화염속도측정에 대한 연구

변정주(Jung Joo Byun) 한국연소학회 2012 한국연소학회지 Vol.17 No.2

Laminar flame speeds of Methane at elevated temperatures and pressures were investigated using constant volume spherical chamber. Pressure trace during combustion was measured in each test and this was used in calculating laminar flame speed of Methane. To have large amount of data, experimental apparatus was fabricated with fully automatically controlled feature. A calculating code which calculates laminar flame speeds at various temperatures and pressures with one experimental result was used to calculate laminar flame speeds. The experimental and calculating methods were verified using the calculated laminar flame speed result with PREMIX code.

복사 열손실을 받는 대향류 확산화염의 맥동 불안정성의 비선형 거동

이수룡(Su Ryong Lee),박성천(Sung Cheon Park) 한국연소학회 2012 한국연소학회지 Vol.17 No.3

Nonlinear dynamics of pulsating instability in radiating counterflow diffusion flames is numerically investigated by imposing Damkohler number perturbation. Stable limit-cycle solutions occur in small ranges of Damkohler numbers past bifurcation point of instability. Period doubling cascade and chaotic behaviors appear just before dynamic extinction occurs. Nonlinear dynamics is also studied when large disturbances are imposed to flames. For weak steady flames, the dynamic extinction range shrinks as the magnitudes of disturbances are increased. However, strong steady flames can overcome relatively large disturbances, thereby the dynamic extinction range extending. Stable limit-cycle behaviors reappears prior to dynamic extinction when the steady flames are strong enough.

100 MWe 순산소 석탄연소 발전시스템의 개념설계-영동 프로젝트

최상민(Sangmin Choi) 한국연소학회 2012 한국연소학회지 Vol.17 No.3

An existing unit of power plant is considered to refurbish it for possible application of carbon capture and storage(CCS). Conceptual design of the plant includes basic considerations on the national and international situation of energy use, environmental concerns, required budget, and time schedule as well as the engineering concept of the plant. While major equipment of the recently upgraded power plant is going to be reused, a new boiler for air-oxy fired dual mode operation is to be designed. Cryogenic air separation unit is considered for optimized capacity, and combustion system accommodates flue gas recirculation with multiple cleaning and humidity removal units. The flue gas is purified for carbon dioxide separation and treatment. This paper presents the background of the project, participants, and industrial background. Proposed concept of the plant operation is discussed for the possible considerations on the engineering designs.

난류분무제트연소에서의 화염구조와 조건평균 통계에 대한 수치적 연구

서재엽(Jaeyeob Seo),허강열(Kang Y. Huh) 한국연소학회 2012 한국연소학회지 Vol.17 No.3

3D DNS is performed for n-heptane spray turbulent jet combustion. Diesel-like conditions are considered including single and multiple injections. Conditional statistics are obtained for multiple Lagrangian flame groups of sequentially evaporating fuel. Each fuel group represents the conditional statistics of an independent Lagrangian flame group. Sequentially evaporating fuel goes through different histories and residence times over the ignition delay period. Multiple flame groups are required for accurate description of combustion of a spray jet that goes through a long injection duration or multiple injections.

차량용 연소식 난방기의 열 및 유동특성에 대한 수치연구

황창환(Chang Hwan Hwang),백승욱(Seung Wook Baek) 한국연소학회 2011 한국연소학회지 Vol.16 No.2

The diesel pre-heater has being used in cabin heating and coolant heating of engine to reduce the engine warm up time for commercial vehicle. The pre-heaters are classified as diesel spray combustor and it forms diffusion flame. By using swirler, a recirculation flow of hot product gases is established near the fuel nozzle and it helps the maintaining of diffusion flame. The design difference of swirler can affect on reaction characteristics and temperature distribution inside pre-heater. The purpose of this study is the investigation of the effect of swirler configuration on combustion characteristics. To solve spray combustion problem, the Euler-Lagrange approach discrete model is used to track droplet trajectory and evaporation history. The PDF equilibrium model is used for chemical reaction model. These models are implemented into the FLUENT code.

상호작용하는 H₂-CO 예혼합 화염에서 H₂선호확산의 영향에 관한 수치적 연구

오상훈(Sanghoon Oh),박정(Jeong Park),권오붕(Ohboong Kwon) 한국연소학회 2012 한국연소학회지 Vol.17 No.3

The effects of strain rate and preferential diffusion of H2 on flame extinction are numerically studied in interacting premixed syngas-air flames with fuel compositions of 50% H₂ + 50% CO and 30% H₂ + 70% CO. Flame stability diagrams mapping lower and upper limit fuel concentrations at flame extinction as a function of strain rate are examined. Increasing strain rate reduces the boundaries of both flammable lean and rich fuel concentrations and produces a flammable island and subsequently even a point, implying that there exists a limit strain rate over which interacting flame cannot be sustained anymore. Even if effective Lewis numbers are slightly larger than unity on extinction boundaries, the shape of the lean extinction boundary is slanted even at low strain rate, i.e. ag = 30 s<SUP>-1</SUP> and is more slanted in further increase of strain rate, implying that flame interaction on lean extinction boundary is strong and thus hydrogen (as a deficient reactant) Lewis number much less than unity plays an important role of flame interaction. It is also shown that effects of preferential diffusion of H2 cause flame interaction to be stronger on lean extinction boundaries and weaker on rich extinction boundaries. Detailed analyses are made through the comparison between flame structures with and without the restriction of the diffusivities of H2 and H in symmetric and asymmetric fuel compositions. The reduction of flammable fuel compositions in increase of strain rate suggests that the mechanism of flame extinction is significant conductive heat loss from the stronger flame to ambience.