湿烟气在开孔翅片管外凝结换热数值模拟

Numerical Simulation on Condensation Heat Transfer of Wet Flue Gas Outside Perforated Finned Tube

为高效回收湿烟气全热并对烟气冷凝换热设备进行优化设计,以设计的紧凑式开孔翅片管换热器为对象,采用欧拉壁膜(EWF)模型与组分输运模型耦合研究低温烟气在翅片管换热器中的凝结换热规律。数值模拟得到的凝结速率及对流凝结换热系数与实验结果最大偏差分别为13.4%和10.9%。结果表明:对流凝结换热系数随入口水蒸气质量分数和烟气流速增大以及管壁温降低而增大,翅片开孔可以起到均压、破坏温度边界层、截断液膜、加快凝结液排出进而强化传热的作用,基于模拟拟合的关于改进雅各布数J的烟气对流凝结关联式与实验数据平均相对误差为13.1%,模拟关联式对于90%的实验结果预测误差在-20%~+20%以内。

In order to recover the total heat of wet flue gas efficiently and optimize the design of flue gas condensation heat exchange equipment,a compact perforated finned-tube heat exchanger was designed.Eulerian Wall Film(EWF) model coupled with the Mixture Species Transport model was employed to study the condensation heat transfer characteristic of low-temperature flue gas in finned-tube heat exchanger.The maximum deviation of condensation rate and convective condensation heat transfer coefficient between numerical simulation and experimental results were 13.4% and 10.9%,respectively.The results show that the convective condensation heat transfer coefficient increases with the increase of water vapor mass fraction at inlet and flue gas flow velocity and the decrease of tube wall temperature.The holes can equalize pressure,destroy temperature boundary layer,cut off liquid film,accelerate condensate discharge and so enhance heat transfer.The average relative error of flue gas convective condensation correlation with improved Jacob's number J fitted by simulation and experimental data is 13.1%,and the predicted error of the simulation correlation is within-20%-+20% for 90% of experimental results.