In this study used Computational Fluid Dynamic analysis to examine NOx reduction in hydrogen combustion, analyzing six conditions with varying air/fuel ratios, temperatures, and concentrations. Results were compared between two combustor shapes and previous experimental data. Findings showed increased air/fuel ratios decreased flame temperature and increased post-combustion O2. NOx emissions peaked at high temperatures and low O2. Numerical results aligned with previous experimental trends, validating the approach. Combustor shape differences, reflecting variations in fuel and air pipes, significantly affected flow rates and combustion positions. This reduced NOx emissions up to a certain air/fuel ratio, but excessive increases diminished this effect. The study highlights the complex relationship between combustor design, operating conditions, and NOx emissions. Further research is needed to optimize NOx reduction by considering pipe numbers and combustion locations. Future studies should explore various combustor geometries, fine-tune air/fuel ratios, and investigate additional parameters influencing NOx formation and reduction in hydrogen combustion systems.

Radiant tubes heat exchangers are critical components that facilitate the heat transfer process to steel in an annealing furnace, and it addresses several engineering problems, such as thermal stress and mechanical failure due to long-term thermal cycling, which can significantly affect the longevity of the tubes and maintenance requirements. In this study, we used commercial software (ANSYS) to simulate the thermal stress and deformation of radiant tubes subjected to extreme thermal conditions and pressure loads. We evaluated both thermally induced deformation and creep deformation, which is a time-dependent deformation under constant stress over the long term. The results showed that uneven temperature conditions and pressure loads lead to significant deformation and potential failures. To mitigate these engineering challenges, we also tested several designs that include supporting brackets. This study provides valuable insights for designing radiant tube heat exchangers in annealing furnaces to extend their lifespan and ensure system safety.

본 연구에서는 현재 신교통 수단으로 연구 중인 바이모달 트램의 전용 교량을 개발하는데 있어 바이모달 트램 운행 특성을 고려한 실물크기의 중공화된 프리캐스트 바닥판을 새롭게 설계․제작하여, 신뢰성 있는 비선형 유한요소해석 프로그램(RCAHEST)을 통한 해석 결과와의 비교․분석을 바탕으로 적합성과 타당성을 검증하였다. 하중 재하 위치를 변수로 실험을 수행하여 설계 하중에 비하여 약 8∼9배의 충분한 안전율을 확보하고 있음을 확인하였으며, 본 연구에서 적용한 재료적 비선형성을 고려한 비선형 유한요소해석 프로그램을 통한 해석 결과 역시 콘크리트의 균열 발생 및 철근의 항복을 포함한 파괴시까지의 극한 거동 특성을 비교적 적절히 평가하고 있음을 알 수 있다.