• Research Article

    Numerical Analysis of Ammonia Crackerusing Porous Catalyst for Hydrogen Production

    수소 생산을 위한 다공성 촉매 기반암모니아 분해 반응기의 전산해석적 연구

    Si-Hyun Cho, Gyeong-Min Kim, Yoon-Ho Bae, Yongsub Kim, Chung-Hwan Jeon

    조시현, 김경민, 배윤호, 김용섭, 전충환

    A typical technical problem in a hydrogen society is the difficulty of securing the economic efficiency of hydrogen storage and long-distance transportation. … + READ MORE
    A typical technical problem in a hydrogen society is the difficulty of securing the economic efficiency of hydrogen storage and long-distance transportation. To overcome this issue, a hydrogen carrier is needed that can convert hydrogen to other forms of compounds. Ammonia, in particular, has many practical advantages among hydrogen carriers and is drawing attention as a very suitable substance. Therefore, cracking technology using ammonia into high-purity hydrogen is necessary. In this research, a numerical CFD model of ammonia cracker was developed. Flow and heat transfer characteristics were analyzed by numerical model. Non-uniform temperature distribution causes local cracking reaction of ammonia, and adversely affects hydrogen production process. This research can be used to design large-scale ammonia cracker and efficient hydrogen production process and can contribute to build a hydrogen infrastructure for hydrogen storage/transport/utilization system. - COLLAPSE
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    30 September 2023

  • Research Article

    Detection of Combustion Instability of Gas Turbine Combustor using Convolutional Autoencoder Model

    합성곱 오토인코더 기법을 이용한 가스터빈 연소기의 연소불안정 상태 감지 연구

    Junwoo Jung, Daesik Kim, Jaemin Beak

    정준우, 김대식, 백재민

    This paper presents a method for detecting the system instability in gas turbine combustor. The proposed approach is designed as the convolutional … + READ MORE
    This paper presents a method for detecting the system instability in gas turbine combustor. The proposed approach is designed as the convolutional autoencoder technique so that it offers strong attractivity even if it has a very little data. Additionally, given that it is a solution to enhance the learning effect in this system, it also provides convenience of use to practicing engineers. From these benefits, the detection rate of the system instability in the proposed method is improved while in operation, which is compared with that in both a root-mean-square and a zero-crossing approaches as well-known statistic methods. - COLLAPSE
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    30 September 2023

  • Research Article

    Thermoacoustic Dynamics in an Annular Model Gas-turbine Combustor under Transverse Stochastic Forcing

    횡방향 확률 가진 환경에서 환형 모사 가스터빈 연소기의 열음향적 동특성 분석

    Seungmin Guk, Seonghyun Seo, Minwoo Lee

    국승민, 서성현, 이민우

    Thermoacoustic combustion instabilities arising from the interaction between the unsteady heat release rate and the combustor acoustic mode continue to hamper the … + READ MORE
    Thermoacoustic combustion instabilities arising from the interaction between the unsteady heat release rate and the combustor acoustic mode continue to hamper the development and operation of continuous combustion systems. In this study, we analyze the thermoacoustic dynamics in an annular model gas-turbine combustor, specifically focusing on the bifurcation behavior and the noise-induced dynamics. For this purpose, we transversely excite the combustor with stochastic signals of varying intensity. We find that a supercritical bifurcation occurs for a transverse thermoacoustic mode, and investigate the dynamics of that mode using the noise-induced dynamics of the flame. The devices and the framework used in this study can potentially serve as a platform for investigating the wide variety of noise-induced behavior in an annular combustor. - COLLAPSE
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    30 September 2023

  • Technical Notes

    Review on Reporting Method of NOx for a Hydrogen Turbine

    수소터빈 도입에 따른 NOx 평가 방법 고찰

    Daesik Kim, Min Kuk Kim

    김대식, 김민국

    The fuel conversion for a stationary gas turbine from conventional LNG to hydrogen is recognized as a key technology for carbon neutrality … + READ MORE
    The fuel conversion for a stationary gas turbine from conventional LNG to hydrogen is recognized as a key technology for carbon neutrality in power generation. However, the present NOx reporting method does not properly evaluate NOx generated from hydrogen combustion. The current standard uses NOx, which has been corrected to the reference oxygen concentration(15%) after complete extraction of H2O from the exhaust gas. For a hydrogen combustion, the concentration of H2O and O2 in the exhaust gas increases more than that of hydrocarbon fuels, resulting in over-reporting the actual NOx emission. In this study, under the operating conditions of hydrogen turbines currently being developed, NOx is calculated to be 39.6% over actual emissions affecting the environment. Therefore, it is very important and urgent to establish a new and appropriate NOx reporting method to accurately consider the characteristics of hydrogen combustion. - COLLAPSE
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    30 September 2023

  • Research Article

    Analysis of the Effects of Pressure and Unmixedness on NOx Emissions in a Model Gas Turbine Combustor

    모형 가스터빈 연소기에서 NOx 배출량에 미치는 압력 및 비혼합도 효과 분석

    Yuangang Wang, Soon Been Park, Chae Hoon Sohn

    왕위엔강, 박순빈, 손채훈

    Pressure effects on NOx emission in a gas turbine combustor are numerically investigated in the present study. Initially, fully premixed flame condition … + READ MORE
    Pressure effects on NOx emission in a gas turbine combustor are numerically investigated in the present study. Initially, fully premixed flame condition with air and fuel injection at the combustor inlet is examined. Increasing pressure leads to a 0.08% rise in flame temperature and a significant 30% increase in NOx emissions. Technically premixed flame condition is then conducted. NOx emissions rise from 1.3 to 3 bar but decline beyond 3 bar due to combined pressure and mixing effects. Applying the NOx emission calibration formula, which accounts for pressure-induced changes while eliminating mixing influence, reveals a direct link between increased pressure and higher NOx emissions. - COLLAPSE
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    30 September 2023
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