NUMERICAL INVESTIGATION OF VAPOR-LIQUID FLOW AND HEAT-TRANSFER IN CAPILLARY-POROUS MEDIA

The transient two-phase flaw and phase change heat transfer processes in porous media are investigated. Based on an enthalpic approach, a on e-domain formulation of the problem is developed, avoiding explicit in ternal boundary tracking between single- and two-phase regions. An eff icient numerical scheme is applied to obtain the solution on a Fred tw o-dimensional grid. The transient response of a liquid-saturated, self -heated porous bed is examined in detail. A physical interpretation of the computed response to fast power transients is attempted Compariso ns with experimental data are made regarding the average void fraction and the limiting dryout heat flux. The numerical approach is extended , keeping the one-domain formulation, to include the surrounding wall structure in the calculation.