VOF Simulations of Evaporation and Condensation Phenomenon Inside a Closed-Loop Thermosyphon

The present work investigates heat and mass transport phenomena inside a thermosyphon using computational fluid dynamics (CFD) simulations by considering water as working fluid. The CFD model was developed using the volume of fluid (VOF) approach to simulate the two-phase flow hydrodynamic during steady state operation of the thermosyphon. The predicted results were compared with the experimentally obtained temperature distribution data along the height of the thermosyphon. A good agreement was found between the predicted and measured temperature data, thus confirming the predictive capability of the computational model. The heat transfer inside the thermosyphon was analyzed using temporal variation of temperature inside the thermosyphon. The water boiling concept was used to demonstrate the phase change phenomena in the evaporator region, while film boiling was demonstrated at the condenser zone. The temperature distribution was used to estimate the thermal conductivity of the thermosyphon. The study will be helpful to address all aspects of two-phase flow hydrodynamic and heat transfer phenomena during the operation of a straight thermosyphon and suggest modifications to improve the thermal conductivity.