基于仿生结构对水平管降膜蒸发换热的模拟

水平管降膜蒸发器是广泛应用于海水淡化和化学工业等方面的换热设备。建立了三维数值模型，采用VOF(volume of fluid)方法结合UDF(user defined function)程序对水平管外降膜蒸发过程的换热特性进行了数值模拟研究，深入研究了光管和强化管针对不同管间距、喷淋密度、蒸发温度和管径对液膜厚度以及平均传热系数的影响。模拟结果表明：在相同条件下，强化管的平均传热系数要明显高于光管，可见基于仿生学原理优化换热表面结构能有效提高水平管外降膜蒸发的换热效率。光管和强化管的平均传热系数随着蒸发温度的升高都呈上升趋势，随喷淋密度的增加呈先上升后减少的趋势。光管和强化管的平均换热系数随管间距的增大而增大，随喷淋密度的增加呈先增加后减少的趋势；换热管的平均传热系数随着蒸发温度升高而升高，随喷淋密度的增加呈先上升后下降的趋势。

Simulation Study On The Heat Transfer Characteristics Of Horizontal Tube Falling Film Evaporation Based On Optimized Bionic Structure

Horizontal tube falling film evaporator is widely used in seawater desalination and chemical industry. In this paper, a three-dimensional numerical model is established, and the heat transfer characteristics of falling film evaporation process outside the horizontal tube are numerically simulated using VOF method and UDF program. The effects of different tube spacing, spray density, evaporation temperature and tube diameter on the liquid film thickness and average heat transfer coefficient of smooth tube and enhanced tube are deeply studied. The simulation results show that under the same conditions, the average heat transfer coefficient of the strengthened tube is significantly higher than that of the smooth tube. It can be seen that optimizing the heat transfer surface structure based on the bionics principle can effectively improve the heat transfer efficiency of falling film evaporation outside the horizontal tube. The average heat transfer coefficients of the smooth tube and the strengthened tube increased with the increase of evaporation temperature, and increased first and then decreased with the increase of spray density. The average heat transfer coefficients of smooth tubes and strengthened tubes increase with the increase of tube spacing, and increase first and then decrease with the increase of spray density; The average heat transfer coefficient of heat exchange tube increases with the increase of evaporation temperature, and then decreases with the increase of spray density.