The accuracy of 3D simulations of flow boiling was improved on the field of turbulence and non-drag forces modelling. The shear-stress turbulence model was included to better describe the turbulence in the two-phase boundary layer. The set of models for interfacial transport of momentum was defined on the basis of the analysis of non-drag forces. Simulations were validated on the boiling flow experiments, performed in vertical annulus with the refrigerant R-113.
COBISS.SI-ID: 21322279
A general near-wall model model for momentum transfer at boiling flow was developed. The model takes into account the influence of nucleation on the evolution of velocity profile in the boundary layer. It is pressumed that the bubble nucleation influences the liquid flow in the similar way as the surface roughness. By using the near-wall model, we have successfully simulate near-wall velocity distribution at various boiling flow experiments.
COBISS.SI-ID: 22319911
The research was carried out in cooperation with the research center Forschungszentrum Dresden. A convective boiling model was used for simulation of boiling flow in the hot channel of PWR fuel assembly. The influence of mixing vanes was analysed as well. The simulations of local thermal loading of fuel rods during boiling were performed among the first in world.
COBISS.SI-ID: 20594215
Flow boiling at very high heat fluxes was simulated. A simplified model of critical heat flux was used and tested. The CHF model was based on the mechanism of bubble merging on the wall followed by formation of the vapor cloths between the wall and liquid. Boiling flow experiments at high heat fluxes close to critical heat flux were simulated. The model was able to predict the local wall temperature rise and the near-wall void fraction increase , which are characteristic phenomena of critical heat flux.
COBISS.SI-ID: 22324519
Condensation in stratified flow of cold water and hot steam in horizontal pipe was simulated. The heat transfer model based on the energy of small turbulent eddies in the vicinity of interfacial area was implemeted to model the condensation heat transfer. It was shown that the condensation in the stratified flow induced instability of the interface, which eventually leads to the transition from stratified to slug flow.
COBISS.SI-ID: 22549543