CFD 시뮬레이션을 이용한 목재펠릿보일러 구조 변경에 따른 열효율 특성 분석

Abstract

This study was performed to confirm the thermal efficiency characteristics of a wood pellet boiler according to the structural changes using Computational Fluid Dynamics (CFD). On the long operation of the boiler, a large amount of contamination was found in the combustion chamber, which reduced the thermal efficiency. In addition, the thermal stress problem in the combustion chamber wall was generated by the flame. To solve this problem, the refractory material was applied to the position where the thermal stresses occurred. Therefore, the fire tube and baffle structure were changed to reduce the decrease in efficiency due to contamination fouling. The heat flow characteristics, including the convective heat transfer coefficient were investigated through the structural change, and a simulation was performed using CFD. The fire tube diameter was increased to 9.3 mm to reduce the decrease in energy transfer due to fouling from contamination. The simulation was performed in three different refractory material thickness (10 mm, 20 mm, and 30 mm) cases. The highest efficiency, approximately 81.64%, was found in the 20 mm case. The high efficiency, approximately 83.43%, was observed in the 663 mm baffle length case. Similarly, in the 7 mm gap between the fire tube and baffle, a higher thermal efficiency, approximately 93.65%, was predicted.