• Research Article

    An Experimental Study on Improving Thermal Efficiency of a Double Cooktop Burner through Stabilization of Inner Burner

    쿡탑 더블 버너에서 내부 화염 안정화를 통한열효율 향상에 관한 실험적 연구

    Yangho Kim, Seungyoon Kim, Jongho Lee, Youngsoo Kim and Chunghwan Jeon

    김양호, 김승윤, 이종호, 김영수, 전충환

    An experimental study was performed to investigate the stabilization mechanism of inner flame in a double-flame cooktop burner. Several hypotheses were made ... + READ MORE
    An experimental study was performed to investigate the stabilization mechanism of inner flame in a double-flame cooktop burner. Several hypotheses were made on CO emission and unstable mechanisms, such as concentration and flow effects. Flow characteristics and flame structure were observed by PIV (Particle Image Velocimetry) and OH PLIF (Planar Laser Induced Fluorescence) measurements respectively. We also could found that internal recirculation of exhausted gases and flow dynamics such as turbulent intensity, strain rate and vorticity were very important in stabilizing the inner flame. To design the high-efficiency and environment-friendly double cooktop burner, CO emission and thermal efficiency must be optimized under circumstances such as regulation limits, customer’s needs and so on. - COLLAPSE
    June 2019
  • Research Article

    Development of Thermoacoustic Network Model Using Transfer Matrix Method

    전달 행렬 기법을 이용한 열음향 네트워크 모델 개발

    Jeongun Park, Myunggon Yoon and Daesik Kim

    박정운, 윤명곤, 김대식

    In this paper, one-dimensional thermoacoustic model based on the transfer matrix approach is developed for studying combustion instabilities in a gas turbine ... + READ MORE
    In this paper, one-dimensional thermoacoustic model based on the transfer matrix approach is developed for studying combustion instabilities in a gas turbine combustor. Two different transfer functions are introduced for the closed-loop feedback system analysis. One is acoustic transfer function, which is derived from the conservation equations such as mass, momentum, and energy for a given problem. The other is flame transfer function, which quantifies the heat release response in the combustor to the incoming velocity fluctuations. Combining the acoustic and flame transfer functions, one can analyze the combustion instability in the closed-loop system. The calculated thermoacoustic instability behavior using the current model matches well with the experimental results in the literature. - COLLAPSE
    June 2019
  • Research Article

    Subcritical Bifurcation of Two Self-Excited Interacting Swirl Flames

    상호작용하는 두 스월 안정 화염에서 발생하는 준임계 분기 현상

    Jiho Lee, Junhyeong Park, Dongsik Han and Kyu Tae Kim

    이지호, 박준형, 한동식, 김규태

    The nonlinear bifurcation behavior of two self-excited interacting swirl flames was investigated in a model lean-premixed gas turbine combustor. We examined the ... + READ MORE
    The nonlinear bifurcation behavior of two self-excited interacting swirl flames was investigated in a model lean-premixed gas turbine combustor. We examined the system’s thermoacoustic state using several time series analysis methods, including spectrograms, phase portraits, and recurrence plots. It was shown that the state of the system in response to the variation of the combustor length is influenced by the presence of multiple attractors, eventually leading to an extremely large amplitude limit cycle via a subcritical bifurcation. - COLLAPSE
    June 2019
  • Research Article

    Usability Consideration of Interconverted Emission Indexes Between Various Pollutant Index Units

    공해물질 배출지수 단위간의 상호 변환을 통한 호환 배출지수의 유용성 고찰

    Chang-Eon Lee, Hohyun Yu, Taejoon Park, Hanjin Kim, Jungseong Lee and Kyungtaek Woo

    이창언, 유호현, 박태준, 김한진, 이중성, 우경택

    This study presents an organized interconverting method between various pollutant units used in emission and regulation indexes. This method firstly converts some ... + READ MORE
    This study presents an organized interconverting method between various pollutant units used in emission and regulation indexes. This method firstly converts some emission index into original index (mi/mf), and then it is converted to any indexes to be found using the interconverting factor (ICF) between these two indexes. For that purpose, information on the fuel composition and combustion conditions are required along with emission index. If we use the converted index expressed as measurement index (mg/m3) under the same combustion condition, it is possible to grasp the quantitative relationship between various indexes. Also, using the total mass of pollutants makes it possible to judge the influence of the regulation index of various equipment on ambient particulate matter. - COLLAPSE
    June 2019
  • Research Article

    Numerical and Experimental Studies on Devolatilizaton Behavior of Pulverized Coal in a Drop Tube Furnace

    DTF내 미분탄의 탈휘발 거동 해석 및 실험

    Jihoon Jang, Karam Han, Geun Sil Yu, Wook Ryun Lee, HyeonSoo Lim and Ho Young Park

    장지훈, 한가람, 유근실, 이욱륜, 임현수, 박호영

    Devolatilization behavior of pulverized coal in a drop tube furnace (DTF) has been calculated with the measured gas temperature and velocity. The ... + READ MORE
    Devolatilization behavior of pulverized coal in a drop tube furnace (DTF) has been calculated with the measured gas temperature and velocity. The particle temperature and velocity were calculated from the energy and momentum equations of particle by using the fourth order Runge-Kutta method. The volatile evolved from the particle along with the reactor tube was also calculated varying the wall temperature of reaction tube as well as the particle diameter. The optimal kinetic parameters of subbituminous coal were obtained from the volatile evolution data of the devolatilization experiment in the DTF by error minimization. - COLLAPSE
    June 2019
  • Research Article

    Experimental Study of Co-combustion Characteristics of Coal and Sewage Sludge Solid Fuel in Pilot-scale Bubbling Fluidized Bed

    파일럿 규모의 기포 유동층 반응기를 이용한 석탄과 하수 슬러지 고형 연료의 혼소에 대한 실험적 연구

    Donghee Kim, Hyungjun Ahn, Kang Y. Huh and Youngjae Lee

    김동희, 안형준, 허강열, 이영재

    In this study, the co-combustion characteristics of coal and sewage sludge were investigated using 100 kWth bubbling fluidized bed (BFB) combustion system ... + READ MORE
    In this study, the co-combustion characteristics of coal and sewage sludge were investigated using 100 kWth bubbling fluidized bed (BFB) combustion system. Sub-bituminous coal (Coal), dried sewage sludge solid fuel (DSS), and hydrothermal carbonization sewage sludge solid fuel (HTCSS) were considered as fuel blends. The higher heating value of HTCSS was about 1,500 kcal/kg higher than that of DSS since the fuel ratio, H/C and O/C ratio were improved by the hydrothermal carbonization. The hardgrove grindability index (HGI) was performed to understand the feasibility of industrial applications. In the pilot-scale BFB experiment, the heat input, as 72 kWth, was fixed in all cases. The mixing ratios of HTCSS and DSS were 2, 5 and 10% respectively based on the higher heating value. Under the co-combustion conditions, the temperature in the reactor was increased in the freeboard zone due to the higher volatile matter of HTCSS and DSS than Coal. The trend of CO and NOx emissions was similar in all cases as mixing ratio was increased. However, SO2 emission was decreased in HTCSS co-combustion case due to the lower sulfur content compared to than that of DSS. Ash acquired after BFB combustion was analyzed by XRF to evaluate the slagging/fouling tendency. The variation of slagging/fouling tendency was minor in all cases. - COLLAPSE
    June 2019