Coupling of a population balance approach with the RPI wall boiling model: Parameter investigation & inhomogeneous MUSIG-RPI validation

The capabilities of CFD for wall boiling are investigated. In the DEBORA tests Dichlorodifluoromethane (R12) was used as the working fluid. This facilitated measurements of radial profiles for gas volume fraction, gas velocity, liquid temperature and bubble size. Coupling the wall boiling model with a population balance model several phenomena can be described. Measurements show an increase of bubble size by coalescence after leaving the heated wall. Increasing the inlet temperature and the amount of generated vapour a shift of the measured radial gas fraction profile from wall to core peak was observed. The explanation is the changing lift coefficient for large bubbles, which can be considered by the inhomogeneous MUSIG population balance model.