Seawater falling film evaporation on vertical plates with turbulence wires Original Research Article

In the European project EasyMED an innovative, multi-effect distillation plant for seawater desalination is being developed. The basic elements of each effect are plates. On one side of the plate seawater is distributed (falling film), whereas on the other side the plate is heated. In our investigation we concentrate on the thermal resistance of the evaporating falling film. In order to decrease this resistance so-called turbulence wires are immersed in the film. Our task is the numerical investigation of this system. It will be shown that purely hydrodynamic numerical experiments with only one wire are not sufficient to determine the optimal distance between the wires. The consideration of the temperature field and the simulation of film flow around two wires both strongly modify the previous finding. Finally, an extension of Nusseltʹs one-dimensional model for an evaporating falling film without wires is presented which fully accounts for the effect of the salinity.