Four field flow modeling of forced convective boiling

A two-phase, four-field computational fluid dynamics (CFD) model was implemented in ANSYS CFX and subsequent three-dimensional calculations were compared with experimental data collected from an R134a experimental test facility. These calculations considered the following four fields for mass, momentum, and energy continuity - continuous liquid, dispersed vapor (bubbles), continuous vapor, and dispersed liquid (droplets). This four-field approach enabled CFD calculations to transition smoothly between the flow regimes present in heated, multiphase flows without the use of a-priori heuristics or flow-regime mapping. Such flow regimes included subcooled nucleate boiling, transition flow, annular flow, and dryout in three dimensions. This two-fluid, four-field model and related closure relationships predicted a variety of experimental data for multiple combinations of inlet temperatures, pressures, test section powers, and inlet velocities in a vertically oriented R134a flow loop.