排液板对横管降膜流动和换热的影响分析

Impact Analysis of Liquid Discharge Plate on Horizontal Tube for Falling Film Evaporation

为了研究排液板对横管降膜流动和换热的影响,建立基于复合Level Set-VOF方法的横管降膜流动和换热数学模型。模拟结果与文献试验数据基本吻合。研究结果表明:在小流量薄膜流动情况下,加装排液板横管能缓解由于液滴间歇性滴落引起的"干斑"现象,稳定管外液膜;使管外液膜分布更均匀,进而影响管外液膜温度分布。加装排液板抑制底部的碰撞混合;增大流量将进一步导致液膜滞止区的形成,恶化传热。加装排液板可加快横管底部的液膜流速。

With an attempt to study the influence of the discharge plate in a horizontal tube,the mathematic model for the flowand heat transfer of the horizontal tube was established using the coupled Level-Set and Volume of Fluid method.The simulationresults are in agreement with the experimental data.The results show that in the case of small flow discharge plate can stable theliquid film an d alleviate“dry spot”phenomenon due to intermittent drip.The liquid film distribution of horizontal tube withdrainage plate is more uniform,which can affect the temperature distribution of liquid film.Horizontal tube with drainage platecan restrain the collision and mixing at the bottom of tube.Increasing flow rate lead to the formation of stagnation zone of the liquidfilm and the deterioration of heat transfer.Adding liquid discharging board can speed up the liquid film flow rate at the bottom ofhorizontal tube.