• Research Article

    Thermo-acoustic Instability by Increased Hydrogen Content in Impinging Jet Flames of Syngas Fuel - Part I : Noise Radiation Characteristics by Self-excited Oscillation

    합성가스 충돌제트화염에서 수소함량 증가에 따른 열음향 불안정성 - Part I : 자려진동에 의한 소음방사 특성

    Juhan Kim and Keeman Lee

    김주한, 이기만

    In this study, various equivalence ratios and Reynolds numbers were used to investigate the thermo-acoustic instability in the impinging jet flame using ... + READ MORE
    In this study, various equivalence ratios and Reynolds numbers were used to investigate the thermo-acoustic instability in the impinging jet flame using syngas fuel. Various instability modes occurred in syngas of H2:CO=50:50 composition ratio, and this study focused on the description of the characteristic of each mode and tendency analysis. It was classified into 4 types of Regime by equivalence ratio and Reynolds number, that is, Regime II-1, II-2, II-3, and II-4 respectively. The shapes of the flame and the flow field in representative conditions of each regime were visualized, and the pressure fluctuation data were verified to be clearly different through various methods (FFT, phase portrait, recurrence plot). Also, there was a section in which the frequency and intensity of the noise decreased as the heat capacity(equivalent ratio or Reynolds number) increased, and it is another criterion for dividing the regime. Finally, the sensitivity was confirmed through the correlation between the two dominant frequencies (II-1, II-3) and Reynolds number, equivalence ratio. - COLLAPSE
    March 2021
  • Research Article

    Curvature Distribution of Lean-Premixed Mesoscale Multinozzle Hydrogen Flames

    희박 예혼합 메조스케일 다중노즐 수소 화염의 곡률 분포

    Taesong Lee and Kyu Tae Kim

    이태송, 김규태

    Local structures of lean fully-premixed hydrogen-air flames in a mesoscale multinozzle array were studied in a tunable combustion test facility, using instantaneous ... + READ MORE
    Local structures of lean fully-premixed hydrogen-air flames in a mesoscale multinozzle array were studied in a tunable combustion test facility, using instantaneous OH PLIF measurements and subsequent image processing techniques. We observe that under thermoacoustically stable conditions, pure hydrogen flame ensemble takes on a conical structure and they are stabilized in isolation without strong flame-to-flame interactions. Under unstable conditions, however, marked flame front deformation and cusp formation occur due to high amplitude velocity fluctuations. Our curvature calculation results reveal that the probability density function distribution is characterized by a positive average value, meaning that the formation of convex contours is more pronounced in lean-premixed pure hydrogen combustion environment. - COLLAPSE
    March 2021
  • Research Article

    Prediction of Combustion Rate of High-Volatile Bituminous Coal through Petrographic Analysis

    Petrography 분석을 통한 고휘발 역청탄의 연소율 예측

    Ji-Hwan Lee, Dae-Gyun Lee, Yanuar Yudhi Isworo and Chung-Hwan Jeon

    이지환, 이대균, 야누아르유디이스워로, 전충환

    The purpose of this study is to predict the combustion rate of high-volatile bituminous coal which is one of the important factors ... + READ MORE
    The purpose of this study is to predict the combustion rate of high-volatile bituminous coal which is one of the important factors in determining the combustion conditions of a power plant. A method of predicting the combustion rate was proposed by integrating the petrography analysis elements related to the combustion rate. Since inertinite had a major effect on the combustion rate, it was possible to predict the combustion rate basically through the inertinite fraction, and petrofactor A was proposed by considering the Vitrinite reflectance value, and more accurate prediction was possible. Petrofactors B and C were proposed by additionally considering the standard deviation of vitrinite reflectance and the effect of liptinite to petrofactor A. The combustion rate could be more accurately predicted. Finally, petrofactor D was proposed considering all the previous factors, and the combustion rate was most accurately predicted. - COLLAPSE
    March 2021
  • Research Article

    Combustion Instability Characteristics of a Model Gas Turbine Burning Coal Gas with Different Combustor Geometries

    석탄가스 모델 가스터빈의 연소실 형상 변화에 따른 연소불안정 특성

    Gyu Seong Youn, Won Joon Song and Dong Jin Cha

    윤규성, 송원준, 차동진

    Combustion instability of a synthetic coal gas flame in a partially-premixed gas turbine combustor has been numerically studied by utilizing a lumped ... + READ MORE
    Combustion instability of a synthetic coal gas flame in a partially-premixed gas turbine combustor has been numerically studied by utilizing a lumped network code, OSCILOS. Both H2 percentage of the coal gas consisting H2 and CH4 and the length of the combustor were varied in this study. A companion experimental data were borrowed and used for validating the numerical results. The predicted results reasonably agree well with the afore-mentioned experimental ones. It was found that the mode of the instability shifted to the higher mode when H2 content of the gas became larger, and that the dominant frequency of the instability was reduced as the combustor was getting longer. - COLLAPSE
    March 2021
  • Research Article

    Application of CMC Model in 0D Simulation of Diesel Engine

    디젤 엔진 0D 해석을 위한 CMC 모델 응용

    Jaesung Kwon, Jeonghyeon Yang and Beomsoo Kim

    권재성, 양정현, 김범수

    A numerical analysis of the diesel engine performance and pollutant emissions was conducted by 0D simulation based on the CMC combustion model ... + READ MORE
    A numerical analysis of the diesel engine performance and pollutant emissions was conducted by 0D simulation based on the CMC combustion model for turbulent diffusion flames. For the combustion analysis, the CMC model, the skeletal mechanism for n-heptane and the NOx mechanism included in GRI 3.0 were used. The evaporation process of fuel was simulated using the multizone spray model, and the density weighted PDF for the mixture fraction was calculated in real time based on the momentum conservation principle with the empirical models for spray tip velocity. The analysis was conducted by applying a multiple flame structure to the operating conditions of the multi-stage fuel injection method, and the predicted results well matched to the experimental data ​​for the pressure variations. It also shows good qualitative and quantitative results for NOx. - COLLAPSE
    March 2021
  • Research Article

    Numerical Study on H2 Enriched NG Lean Premixed Combustion

    수소첨가 천연가스 희박예혼합 연소에 대한 수치해석 연구

    Youngjun Shin and Eun-Seong Cho

    신영준, 조은성

    Hydrogen enriched LNG flame is tested to understand hydrogen effect on the flame such as temperature, flame speed, emissions (NOx, CO ... + READ MORE
    Hydrogen enriched LNG flame is tested to understand hydrogen effect on the flame such as temperature, flame speed, emissions (NOx, CO), and extinction at lean premixed (ф=0.4~0.6) various pressure (p=1~25 bar) conditions using CHEMKIN-Pro with GRI 3.0 detailed chemistry. Hydrogen flame temperature is much higher than that of LNG, which may affect high NOx emission production. The flame speed increases with the addition of H2, so a design speed change should be considered to prevent flashback at the nozzle. The addition of H2 reduces CO emissions and increases NOx emissions, but can be overcome with a lower equivalent ratio due to the increased flame stabilization due to the addition of H2. Extinction stretch rate gradually increases with hydrogen addition which shows that enriched hydrogen LNG premixed flame could be sustainable in high turbulent condition which means more stable than LNG itself flame. Even though in 100% H2 operating condition, gas turbine operating condition shows similar combustion air and exit flue gas flow rate with LNG which means the compressor and turbine may not need major modification. - COLLAPSE
    March 2021
  • Technical Notes

    The Needs for R& D of Ammonia Combustion Technology for Carbon Neutrality - Part Ⅰ Background and Economic Feasibility of Expanding the Supply of Fuel Ammonia

    탄소중립을 위한 암모니아 연소기술의 연구개발 필요성- Part Ⅰ 연료 암모니아의 보급확대 배경과 경제성

    Hookyung Lee, Youngmin Woo and Min Jung Lee

    이후경, 우영민, 이민정

    Along with a global carbon neutral basis, the development of combustion technologies for greenhouse gas reduction is essential. Transitional technologies that are ... + READ MORE
    Along with a global carbon neutral basis, the development of combustion technologies for greenhouse gas reduction is essential. Transitional technologies that are easy to commercialize within a relatively short period of time are required for the reinforced environmental pollutant reduction regulations and fulfillment of the promise with the international community. As a carbon-free fuel, ammonia is expected to play a important role through hydrogen energy carriers and direct use technology. This paper examines the history of the energy and resource sectors up to the formation of a carbon-neutral system in Korea, and also investigates the necessity of using ammonia to advance to a hydrogen economy. In order to secure the technical feasibility of ammonia combustion, this article discusses related domestic and foreign policies, the current state of the life cycle technology development from fuel ammonia production process to utilization, the characteristics of fuel ammonia, and the possibility of application as a combustion technology. This paper is divided into two parts, and in Part 1, we will discuss the background and economic feasibility of expanding the supply of fuel ammonia. - COLLAPSE
    March 2021
  • Technical Notes

    The Needs for R& D of Ammonia Combustion Technology for Carbon Neutrality - Part Ⅱ R& D Trends and Technical Feasibility Analysis

    탄소중립을 위한 암모니아 연소기술의 연구개발 필요성- Part Ⅱ 연구개발 동향과 기술적 타당성 분석

    Hookyung Lee, Youngmin Woo and Min Jung Lee

    이후경, 우영민, 이민정

    Following the previously published Part 1, the Part 2 focuses on the basic combustion characteristics of fuel ammonia and research cases of ... + READ MORE
    Following the previously published Part 1, the Part 2 focuses on the basic combustion characteristics of fuel ammonia and research cases of applied combustion technology. In addition, we would like to review the items necessary for a large-scale demonstration of ammonia combustion technology. Most of the technologies for utilizing ammonia combustion are being carried out in Japan and are strongly promoted by policy. The results give a method of stabilizing flame and reducing nitrogen oxides when mixed burning of ammonia, and are applied to automobile engine, marine engine, gas turbine, coal-fired boiler, reheating furnace, and fuel cell. The co-burning rate, which is advantageous for stabilizing combustion and reducing nitrogen oxides, has been derived, and accordingly, the use of ammonia as a carbon-free fuel for the future is brightly expected. - COLLAPSE
    March 2021