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Research Article
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A Study on the Efficiency Improvement of Fire-tube Boiler Structure and Fuel
노통연관보일러 구조 및 연료 종류에 따른 효율 향상 방안 연구
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Cheol Su Shin, Hyun Kyu Suh
신철수, 서현규
- This study was conducted to improve the thermal efficiency of the furnace-tube boiler to reduce fuel consumption and harmful exhaust emissions. To …
- This study was conducted to improve the thermal efficiency of the furnace-tube boiler to reduce fuel consumption and harmful exhaust emissions. To achieve this, flow analysis of the 3-pass boiler geometry was conducted by applying the SST k - ω turbulence model to simulate the flow of water and heat generated by combustion. The performances of the boiler were compared through the thermal efficiency of the boiler and the heat transfer rates in the furnace, 2nd pass, and 3rd pass. It was revealed that the change in materials and number of tubes showed a maximum thermal efficiency difference of 5.6%, which did not significantly impact the boiler performance. The most substantial efficiency improvement was observed with fuel changes, achieving the highest efficiency of 55.39% with LFG. This showed a 21.6% efficiency difference compared to the 33.78% thermal efficiency of LNG. - COLLAPSE
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A Study on the Efficiency Improvement of Fire-tube Boiler Structure and Fuel
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Research Article
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A Numerical Study on Endothermic Chemical Reactions of Supercritical n-dodecane in a Regenerative Cooling Channel of Hypersonic Vehicles
극초음속비행체용 재생냉각 미세채널 내부 초임계 n-dodecane의 흡열분해 화학반응 수치해석 연구
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Minseo Lee, Hyung Ju Lee, Kwon Young Ko, Yoojun Hwang, Ju Young Lee
이민서, 이형주, 고권영, 황유준, 이주영
- A numerical study has been conducted on the endothermic decomposition reactions of n-dodecane in a regenerative cooling channel by using a multi-step …
- A numerical study has been conducted on the endothermic decomposition reactions of n-dodecane in a regenerative cooling channel by using a multi-step PPD (Proportional Product Distribution) model in order to develop a practical numerical simulation technique for analyzing and designing an active regenerative cooling system of hypersonic cruise vehicles. The PPD model includes the primary cracking which is applicable up to the fuel conversion rate of 13% while the secondary cracking which should be incorporated for the conversion rate of above 13%. Results for both the primary and secondary cracking regions show that the fuel outlet temperature is lower when the thermal cracking is considered due to the endothermic nature of the reaction. Furthermore, the predicted distributions of major gaseous and liquid products with respect to the fuel conversion rate agree very nicely with existing numerical and experimental data, which confirms the validity of the numerical technique applied in the current study. - COLLAPSE
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A Numerical Study on Endothermic Chemical Reactions of Supercritical n-dodecane in a Regenerative Cooling Channel of Hypersonic Vehicles
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Research Article
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Analysis of Pressure Effect on NOx Emission Predicted by EDC Models Adopted in a Model Gas Turbine Combustor
모형 가스터빈 연소기에서 EDC 수치 모델 선택에 따른 NOx 배출에 미치는 압력 효과 분석
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Soon Been Park, Yuangang Wang, Chae Hoon Sohn
박순빈, 왕위엔강, 손채훈
- Pressure effects on NOx emission in a gas turbine combustor are numerically investigated using the EDC model in the study. To validate …
- Pressure effects on NOx emission in a gas turbine combustor are numerically investigated using the EDC model in the study. To validate the combustion analysis involving air-fuel mixing and chemical reactions under turbulent conditions, we adopt two models of the Standard EDC and Partially Stirred Reactor EDC models and compare one model with the other. As pressure increases, NOx emission decreases slightly to 5.87 ppm with the Standard EDC model adopted, while it significantly increases to 37 ppm with the Partially Stirred Reactor EDC model adopted. While the temperature difference between the two EDC models is negligibly small, NOx emissions predicted by the Partially Stirred Reactor EDC model increase geometrically. This confirms that temperature is not a primary parameter in NOx emissions when comparing EDC models. The correlation between factors expressed by functions of chemical and mixing time scales can be considered to find effects of pressure on NOx emissions. - COLLAPSE
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Analysis of Pressure Effect on NOx Emission Predicted by EDC Models Adopted in a Model Gas Turbine Combustor
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Research Article
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Hydrogen Co-Firing Simulation of an F-class Gas Turbine Combustor Nozzle
F급 가스터빈 연소기 노즐 수소 혼소 전산해석
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Nakjeong Choi, Sanghyup Lee, Seik Park, Jungkeuk Park
최낙정, 이상협, 박세익, 박정극
- Research on hydrogen co-firing gas turbines is actively progressing to achieve carbon neutrality. This study performed Computational Fluid Dynamics (CFD) analysis on …
- Research on hydrogen co-firing gas turbines is actively progressing to achieve carbon neutrality. This study performed Computational Fluid Dynamics (CFD) analysis on a current F-class gas turbine nozzle to assess the feasibility of hydrogen co-firing and enhance asset utilization. Reynolds-Averaged Navier-Stokes (RANS) simulations were employed to analyze combustion characteristics up to a hydrogen co-firing rate of 70%, using the Flamelet Generated Manifold (FGM) model and GRI3.0 mechanism. The simulations accurately predicted the reaction zone, flame length, flame shape, and changes in the recirculation flow induced by increased hydrogen reactivity. However, discrepancies in Heat Release Rate (HRR) due to adiabatic wall boundary conditions in the simulation led to deviations from experimental results, affecting the flame shape and the length, particularly impacting NO predictions above a 50% hydrogen co-firing ratio. The findings of this study can provide fundamental insights for future demonstrations of hydrogen in existing F-class gas turbine combustors. - COLLAPSE
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Hydrogen Co-Firing Simulation of an F-class Gas Turbine Combustor Nozzle
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Research Article
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Development of a Global Mechanism for Ammonia Combustion Assisted by Machine Learning
기계학습을 활용한 암모니아 연소의 총괄 반응식 개발
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Jieun Kang, Seong-kyun Im
강지은, 임성균
- To achieve carbon neutrality, sustainable energy solutions like ammonia are being explored. Ammonia, with its high energy density and existing infrastructure, is …
- To achieve carbon neutrality, sustainable energy solutions like ammonia are being explored. Ammonia, with its high energy density and existing infrastructure, is promising as a hydrogen carrier. This study aims to reduce the computational cost of ammonia combustion simulations by developing a global mechanism using a chemical reaction neural network (CRNN). The CRNN was trained using data from the detailed mechanism by Okafor, resulting in a global mechanism with 4 reactions and 7 species. Performance evaluations showed that the developed global mechanism accurately predicts temperature, species concentrations and ignition delay times, achieving high prediction accuracy for steady-state conditions. The results indicate that the CRNN-based global mechanism significantly enhances computational efficiency and accessibility for ammonia combustion research. - COLLAPSE
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Development of a Global Mechanism for Ammonia Combustion Assisted by Machine Learning
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Research Article
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Explosion Characteristics of Partially Cracked Ammonia Fuel
부분 크래킹된 암모니아 연료의 폭발 특성
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Inho Kim, Seo Hee Cho, Keeman Lee
김인호, 조서희, 이기만
- Ammonia is challenging to apply in existing industrial systems due to its low burning velocity and narrow flammability limits. However, it could …
- Ammonia is challenging to apply in existing industrial systems due to its low burning velocity and narrow flammability limits. However, it could serve as a viable replacement for hydrocarbon fuels by decomposing a portion of the ammonia into hydrogen and nitrogen. In this study, the explosion characteristics of partially cracked ammonia-air premixed flames were experimentally investigated in a cylindrical constant-volume chamber, with initial pressures and ammonia cracking ratios as variables. Ammonia cracking poses a significant risk of explosion due to the presence of hydrogen. By understanding the explosion characteristics of partially cracked ammonia fuels, it is possible to predict the severity of explosions and design safety equipment to mitigate these risks. As the ammonia cracking ratio increased, the burning velocity increased, resulting in a shortened explosion time and an increased maximum rate of pressure rise. - COLLAPSE
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Explosion Characteristics of Partially Cracked Ammonia Fuel
Journal Informaiton
Journal of the Korean Society of Combustion
Journal of the Korean Society of Combustion
