• Research Article

    Study on Experimental and Numerical Modeling of Pyrolysis for Fire Prediction of Polyurethane Foam Insulation Material

    폴리우레탄 폼 단열재의 화재 예측을 위한 열분해 실험 및 수치 모델링 연구

    Yejin Ha, Joonho Jeon

    하예진, 전준호

    Polyurethane foam has been widely used as building materials for energy savings. But, it is weakness to fire because of its flammability. … + READ MORE
    Polyurethane foam has been widely used as building materials for energy savings. But, it is weakness to fire because of its flammability. Polyurethane foam as solid fuel occurs combustion and fire through pyrolysis process. Therefore, understanding the pyrolysis process is essential for fire safety. In this study, the pyrolysis behavior of polyurethane foam was investigated using thermogravimetric analysis (TGA). The results showed that pyrolysis occurred through two distinct mass reductions. The key parameters of pyrolysis reaction rate, such activation energy and pre-exponential factor, were determined based on various model-free and model-fitting methods. Additionally, numerical simulation was conducted using fire dynamics simulator (FDS) to examine the suitability of the pyrolysis modeling from a fire perspective. As a result, it was confirmed that FDS pyrolysis model numerically predicts the two-step reaction of polyurethane foam. - COLLAPSE
    31 December 2023
  • Research Article

    An Analysis of Optical and Morphological Properties of Particulate Matters Emitted from Jet A1-air Diffusion Flames

    Jet A1-공기 확산 화염에서 배출된 입자상 물질의 광학 및 형상학적 분석에 관한 연구

    Byeol Kang, Myung-Ho Ryu, Seul-Hyun Park

    강별, 류명호, 박설현

    Many aircraft and launch vehicles that use Jet A1 as a fuel operate at high altitudes and emit large amounts of particulate … + READ MORE
    Many aircraft and launch vehicles that use Jet A1 as a fuel operate at high altitudes and emit large amounts of particulate matter into the atmosphere. The impact of particulate matter is steadily increasing and requires continuous monitoring and source reduction efforts. Morphological and optical characterization data of PM can be used in concentration measurement and reduction techniques to help quantitatively analyze the damage caused by PM. In this study, dimensionless light extinction coefficient measurements and morphological analysis of PM produced from burning Jet A1 in a coaxial flow burner were performed. The values of fractal dimension and prefactor which can help to quantify the morphological properties of the aggregates of Jet A1 PM, were found to be 1.68 and 2.85, respectively. The scattering albedo value estimated from the morphological properties was 0.094, indicating that the contribution of scattering to the total extinction was about 10%. The results were strongly supported by the fact that the fraction of elemental carbon (EC) composed of PM is dominant compared to organic carbon (OC). These empirical results highlighted that the light extinction by Jet A1 PM was dominated by the effects of light absorption rather than those of light scattering. - COLLAPSE
    31 December 2023
  • Research Article

    Combustion Characteristics of Axial Fuel Staging Nozzles for Gas Turbine Combustors

    가스터빈 연소기용 축방향 다단연소 노즐의 연소특성

    Jeongjae Hwang, Min Kuk Kim, Won June Lee, Kyungwook Min, Do Won Kang, Han-Seok Kim

    황정재, 김민국, 이원준, 민경욱, 강도원, 김한석

    Axial fuel staging (AFS) nozzle variants for applying to heavy duty gas turbine combustors were designed and experimentally investigated in this study. … + READ MORE
    Axial fuel staging (AFS) nozzle variants for applying to heavy duty gas turbine combustors were designed and experimentally investigated in this study. Four AFS nozzle variants (elliptic, dual elliptic, airfoil, and low-swirl type) were designed and single AFS nozzle test was conducted at the 1/4-scale combustion test rig with measurement module consists of 25-points emissions and 30-points exit temperatures. Flame structures were observed with OH-Planar Laser Induced Fluorescence (PLIF) and direct photo. When the fuel split was about 120% of the air split, NOx emission was minimum which is about 80% of the reference. Flame penetration was increased with air split and temperature profile pattern factor was found to be the lowest in dual elliptic nozzle. Four dual elliptics nozzles were mounted in the middle of the can combustor to conduct the full-can combustion test. Minimum NOx emissions were found at 10.4% fuel split, which is 120% of air dsplit. - COLLAPSE
    31 December 2023
  • Research Article

    Effects of Diesel/1-Butanol Fuel Blends on the Performance of a Diesel Engine

    경유/1-부탄올 혼합유가 디젤 엔진 성능에 미치는 영향

    Jaesung Kwon, Beomsoo Kim

    권재성, 김범수

    This study compared the changes in engine performance variables using diesel/1-butanol blended fuels for a naturally aspirated compression ignition diesel engine. The … + READ MORE
    This study compared the changes in engine performance variables using diesel/1-butanol blended fuels for a naturally aspirated compression ignition diesel engine. The concentrations of 1-butanol were 10%, 30%, and 50% by volume. The experimental results showed a decrease in brake torque and brake power using blended fuels due to the lower calorific value and the cooling effect caused by the high heat of vaporization that suppresses combustion reactions. The oxygen contained in 1-butanol can promote combustion reactions and increase thermal efficiency. However, as the 1-butanol volume ratio increases, overall thermal efficiency decreases due to the ignition delay and the lower combustion temperatures. As the engine speed increases, the air-fuel ratio decreases, forming a richer mixture, and the longer ignition delay leads to an increasing trend in exhaust gas temperature. - COLLAPSE
    31 December 2023
  • Research Article

    Flame Stability and Emission Characteristics of Non-Premixed Ammonia Cracking Gas/Air Combustion in a Tangential Injection Burner

    접선 분사 연소기 내 암모니아 크래킹 혼합물/공기 비예혼합 화염의 안정화 및 NOx 배출 특성 연구

    Joo-Won Park, Namsu Kim, Young Tae Guahk, Hookyung Lee, Minjung Lee, Seong-kyun Im

    박주원, 김남수, 곽영태, 이후경, 이민정, 임성균

    Combustion characteristics of partial cracking ammonia gas were investigated using a tangential injection burner. As the cracking ratio increased, the stable operational … + READ MORE
    Combustion characteristics of partial cracking ammonia gas were investigated using a tangential injection burner. As the cracking ratio increased, the stable operational regime expanded, leading to the blowout limit of 𝜙=0.17. Higher injection velocities increased the wall peak temperature due to augmented heat transfer but lowered temperatures near the injector as the high-temperature reaction zone shifted downstream. NO exhibited peak values at 40-60% cracking ratio, attributed to enhanced radical formation with hydrogen addition. Numerical simulations, employing a perfectly stirred reactor model and a steady laminar flamelet model, demonstrated that these models, based on different assumption of flame structure, accurately reproduce NO levels in low and high cracking ratio conditions, respectively. - COLLAPSE
    31 December 2023
  • Research Article

    An Experimental Study on Turbulent Characteristics of Hybrid Type Fractal Grid Flames

    하이브리드타입 프랙탈격자 화염의 난류특성에 관한 실험적 연구

    Jung Hyun Kim, Kee Man Lee

    김정현, 이기만

    This study focuses on the V-shape with hybrid type fractal grid generator to evaluate the turbulent characteristics of turbulent premixed flames. In … + READ MORE
    This study focuses on the V-shape with hybrid type fractal grid generator to evaluate the turbulent characteristics of turbulent premixed flames. In this work, the mean and velocity fluctuation, turbulence intensity were investigated. The integral length scale of non-reactive flow was additionally investigated to obtain a Borghi-Peters diagram. By comparing the Borghi-Peters diagram shown as a result of the non-reactive flow based with the reaction OH-PLIF images, it was confirmed that the flame characteristics of each regimes in fractal grid flames were well represented. Also, the irreguar turbulence of premixed flames was quantitatively analyzed using the flame brushes obtained by the mean progress variable analysis. As a result, the flame brushes of the hybrid type fractal turbulence generator were wider than the conventional fractal grid generator with individuial shape of cross and square grid. This means that the turbulence intensity has increased compared to the previous conventional fractal grid, and the local displacement speed is also expected to increase.it has increased compared to the existing fractals of the hybrid type, and the local displacement speed is also expected to increase. - COLLAPSE
    31 December 2023