This study investigates nozzle diameter and fuel type effects on combustion characteristics and NOx emissions in radiant tube heating systems through numerical simulation. Four fuels were analyzed: LPG, natural gas, coke oven gas, and hydrogen under varying nozzle conditions using computational fluid dynamics with energy conservation, species transport, and thermal NOx formation models. Results show that nozzle diameter optimization significantly enhances internal recirculation, improving fuel-air mixing and reducing NOx formation. Hydrogen exhibits higher flame temperatures, potentially increasing thermal NOx generation, but optimal nozzle design controls this effect through enhanced mixing patterns. The optimized configuration achieved substantial NOx reduction while maintaining combustion stability across all tested fuels.

Abstract
1. 서 론
2. 전산유체역학 해석 준비
    2.1 형상 및 격자
    2.2 경계조건
3. 결과 및 분석
    3.1 노즐 직경에 따른 결과
    3.2 연료 종류에 따른 결과
4. 결 론
후 기
References

• 최락준(Department of Precision Mechanical Engineering, Kyungpook National University) | Rak-Jun Choi
• 김설하(Department of Precision Mechanical Engineering, Kyungpook National University) | Seol-Ha Kim
• 노현석(Research Institute of Science & Technology, Pohang) | Noh Hyeon Seok
• Ryang-Gyoon Kim(Research Institute of Science & Technology, Pohang) Corresponding author
• 권종서(Plantec) | Jong-Seo Kwon