20.500.12556/DKUM-96053 CFD implementation and preliminary validation of a combined boiling model (CBM) for two-phase closed thermosyphons Predicting phase-change heat transfer in two-phase closed thermosyphons (TPCTs) represents a significant challenge owing to the complex interaction of boiling, condensation, and conjugate heat transfer (CHT) mechanisms. This study presents a numerical investigation of a TPCT using the Combined Boiling Model (CBM) within a conjugate heat transfer (CHT) framework. Unlike prior TPCT studies, the CBM integrates an improved RPI-based wall boiling model with sliding bubble dynamics, a laminar film condensation closure, and Lee-type bulk phase change in a single, energy-consistent formulation suited for engineering-scale meshes and time-steps. Building on these extensions, we demonstrate the approach on a vertical TPCT with full CHT and validate it against experiments and a VOF–Lee reference. Simulations for heat loads ranging from 173 to 376 W capture key flow features, including vapour generation, vapour-pocket dynamics, and thin-film condensation, while reducing temperature deviations typically below 3% in the evaporator and adiabatic sections and about 2 to 5% in the condenser. The results confirm that the CBM provides a physically consistent and computationally efficient approach for predicting evaporation–condensation phenomena in TPCTs. heat pipe thermosyphon multiphase conjugate heat transfer Combined Boiling Model (CBM) Euler–Euler toplotne cevi termosifon večfazni tok konjugiran prenos toplote kombinirani model vrenja Eulerjev pristop true false true MDPI Angleški jezik Slovenski jezik https://www.mdpi.com/2311-5521/10/11/296 Članek v reviji 2025-11-27 15:02:57 2025-11-27 15:02:57 2025-11-28 03:08:34 0000-00-00 00:00:00 2025 0 0 30 str. iss. 11, [article no.] 296 Vol. 10 Nov. 2025 0000-00-00 Zaloznikova NiDoloceno NiDoloceno 2025-10-22 2025-11-11 2025-11-13 621.67:620.193.16 258241539 10.3390/fluids10110296 2311-5521 fluids-10-00296-v3_(1).pdf fluids-10-00296-v3_(1).pdf 1 42E5E28B4442EE9F54EA66D68BA095D9 7a8f51d04e19e3a3ecea86e7a2fc7597a0b23e812208bb81e61a351ccbe9ab5e f76ee7a0-cb99-11f0-97c8-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=200929 https://www.mdpi.com/2311-5521/10/11/296 0 fe1a6b81-cb99-11f0-97c8-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=200930 Fakulteta za strojništvo 0 0 0