Simulation of vapor bubble growth in nucleate pool boiling

Tesis Energía y Ambiente (maestría) - Instituto Tecnológico de Buenos Aires - Karlsruher Institut für Technologie, Karlsruhe, 2020 Two-phase flows with phase change are a useful phenomenon for small-scale cooling devices, where high quantities of excess heat need to be removed on a limited frame of space. Bubble formation through evaporation however is a highly dynamic process that still has not been fully investigated and is difficult to control. In order to advance further research in this area, a Volume-of-Fluid based solver is investigated for bubble growth in this thesis. The solver is based on the OpenFOAM solver interFoam and is extended with functionalities to depict evaporation processes. In this thesis, the focus is put on the solver’s ability to correctly simulate evaporation. Especially the phase-change development near the threephase contact line where the two-phase interface and the solid heated surface meet, is of interest. In this area the evaporation reaches high levels of magnitude and therefore needs special consideration. The chosen approach in this solver is a data regression to link these parately calculated values of the three-phase region with the rest of the domain. In this work bubble growth without solid structure, quasi-steady contact line evaporation and saturated pool boiling on a solid surface are simulated and compared against analytical, highly resolved and experimental results. The solver’s models are able to correctly depict the processes within a reasonable margin of error. The bubble growth in a superheated fluid gives an acceptable deviation of radius with respect to Scriven’s analytical solution. Quasi-steady evaporation also confirms the solver’s capability to correctly predict threephase contact line behavior compared to Stephan and Busse’s high-resolution simulation campaign. For saturated boiling the solver is highly dependent on grid resolution and the condensation coefficient f. However, a similar behavior with good agreement to the experiment conducted by Yaboki can be reproduced with an adequate set of parameters.