锅炉中针型烟管换热特性模拟研究

Simulation Study on Heat Transfer Characteristics of Needle-Type Smoke Tubes in Boilers

采用强化传热技术研究了一种针型管换热器,通过数值仿真对比不同布局和结构针型管的换热性能,主要研究了强化传热方式的机理。运用烟管中烟气的流动特性分析,发现其主要流动为层流,导致换热器的换热性能差;通过增加针肋对换热器进行改进,破坏流体的流动边界层,增加流体混合,形成强对流环境,大幅提升了换热器的换热能力。对换热器换热单元流动与热交换过程进行数值仿真,讨论单元域温度场、速度场分布,并与不同工况下数据进行对比分析。分析了针肋的不同数量、高度及排列布置方式对换热器换热性能的影响。仿真数值模拟表明,在恒定温度条件下针肋的不同数量、高度、排列布置方式及烟气负荷对换热器的换热性能有较大的影响。

Enhanced heat transfer technology is employed to investigate a needle-type tube heat exchanger.Through numerical simulations,a comparative analysis of the heat transfer performance of different layouts and structural configurations of needle-type tubes is conducted,with a primary focus on studying the mechanisms behind enhanced heat transfer.By analyzing the flow characteristics of flue gas within the smoke tubes,it is observed that the predominant flow is laminar,which results in sub-optimal heat transfer performance of the heat exchanger.Improvement is achieved by adding needle-like fins to disrupt the fluid's boundary layer,enhance fluid mixing,and create a strong convective environment,thereby significantly improving the heat transfer capability of the heat exchanger.Numerical simulations of the flow and heat exchange processes of the heat exchanger's heat transfer unit are performed,discussing the temperature field and velocity field distributions within the unit domain,and comparing the results with data from different operating conditions.The paper also analyzes the impact of different quantities,heights,and arrangements of the needle-like fins on the heat transfer performance of the heat exchanger.The numerical simulations indicate that under constant temperature conditions,the quantity,height,arrangement,and flue gas load of the needle-like fins have a significant impact on the heat transfer performance of the heat exchanger.