Numerical Analysis of Unsteady Falling Film Condensation on the Outer Wall of Vertical Microtubes: Effects of Tube Diameter, Reynolds Number, and Oscillation Frequency

This study investigates the unsteady behavior of falling film condensation on the outer wall of vertical microtubes, focusing on the effects of tube diameter, Reynolds number, and oscillation frequency of the incoming liquid film flow. A fully coupled interface-tracking solver with an arbitrary Lagrangian-Eulerian (ALE) approach is employed to analyze the hydrodynamic characteristics and thickness distribution of the liquid film. The results demonstrate that tube diameter significantly influences the curvature effects, which in turn affect the heat and mass transfer coefficients during condensation. The study reveals that smaller tube radii enhance the formation of capillary waves, leading to increased heat and mass transfer rates from ۳۰% to ۱۰۰%, depending on the flow and tube configurations. Additionally, the oscillation frequency of the inlet liquid mass flow rate plays a crucial role in the formation of solitary and capillary waves, which further impact the overall heat and mass transfer performance. The findings provide valuable insights for optimizing the design of thermo-fluid micro-systems involving falling film condensation.

کلیدواژه ها:

Wavy falling film condensation ، Axisymmetric flow ، Microtube ، Arbitrary Lagrangian-Eulerian (ALE) ، Interface tracking method