微结构竖管降膜流动与蒸发特性数值模拟OA

Falling film evaporation is a high-efficiency phase change heat transfer method in the energy and chemical engineering field,and existing studies mainly focus on horizontal or smooth vertical tubes.This study uses computational fluid dynamics(CFD)numerical simulation to compare the performance of smooth tubes,rectangular finned tubes,and triangular finned tubes,revealing the regulatory laws and quantitative effects of microstructures on liquid film flow,temperature-velocity field distribution,and evaporation efficiency.The results show that microstructures enhance heat transfer by inducing secondary flow and reshaping liquid film evolution:in the inlet section,the liquid film thickness of two finned tubes reaches 1.3 mm(1.1 mm for smooth tubes)to strengthen near-wall liquid retention;in the fully developed section,the liquid film of rectangular finned tubes fluctuates drastically while triangular finned tubes form a stable flow regime.In terms of temperature and velocity field regulation,triangular finned tubes achieve global temperature homogenization via ordered secondary flow with optimal velocity field uniformity,rectangular finned tubes have local distortion,and smooth tubes have significant initial thermal resistance.Quantitative analysis of evaporation performance shows the evaporation rate of triangular finned tubes reaches 82.6%and that of rectangular finned tubes hits 69.5%,and both have coordinated advantage of moderate disturbance and high stability.