20.500.12556/RUL-140057 Računalniška simulacija konvektivnega vrenja z uporabo populacijskega modela velikosti mehurčkov Computational simulation of convective boiling using population balance model V magistrskem delu so predstavljeni rezultati simulacije konvektivnega vrenja v navpičnem kanalu, ki smo jih izvedli s programom za računalniško dinamiko tekočin ANSYS Fluent. Uporabili smo Eulerjev dvofluidni pristop, ki temelji na fazno povprečenih fizikalnih količinah. Modelirali smo turbulenco, medfazni prenos gibalne količine, energije in mase. Za modeliranje vrenja na steni smo uporabili model razdelitve toplotnega toka. Velikost mehurčka smo modelirali s populacijskim modelom, ki upošteva rast mehurčkov zaradi uparjanja, krčenje zaradi kondenzacije, združevanje zaradi trkov in razpade zaradi turbulence. Rezultate smo primerjali s tremi različnimi eksperimentalnimi primeri DEBORA eksperimentov pri različnih pogojih. Primerjali smo porazdelitve glavnih parametrov dvofaznega toka, kot so volumski delež pare, povprečna velikost mehurčkov in temperatura kapljevine. Na enem primeru smo podrobneje raziskali delovanje populacijskega modela. Analizirali smo vpliv števila velikostnih razredov mehurčkov, temperature kapljevine in stene ter modela razdelitve toplotnega toka. In this master thesis the results of convective boiling simulations using the ANSYS Fluent code are presented. The two-phase flow is described using the Eulerian two-fluid model framework, that is based on the phase averaged equations. Simulations are done with consideration of turbulent momentum, heat and mass transfer between the phases. For wall boiling the heat partitioning model is used. Bubble sizes are modelled using the population balance model that accounts for bubble growth and shrinkage due to evaporation and condensation, coalescence due to collisions and breakage due to turbulence. Simulation results are compared with the experimental results of three different DEBORA cases at different operating conditions. Distributions of main two-phase flow parameters such as void fraction, the average bubble size and the liquid temperature are compared. On one of the cases, the population balance model is studied in more detail. The influence of bubble classes, the liquid temperature, the wall temperate and the effect of heat flux partitioning model is analysed. populacijska enačba vrenje kondenzacija mehurčki ANSYS Fluent DEBORA Eulerjev dvofluidni model model razdelitve toplotnega toka turbulenca population balance model boiling condensation bubbles ANSYS Fluent DEBORA Eulerian two-fluid model heat flux partitioning model turbulence true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2022-09-10 08:15:14 2022-09-10 08:15:16 2022-09-16 04:13:10 0000-00-00 00:00:00 2022 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 126811 120957187 5401.pdf 5401.pdf 1 C26E38A636532A1E170DB90732AF6D20 e498d4b7edf90360a17a424c09b216087975247b6110bd783e9fe9c8ba1a49d1 e1ae1ff5-30cf-11ed-92af-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=160722 Fakulteta za matematiko in fiziko 0 0 0