Numerical simulation of phase transition and heat transfer in two-phase closed thermosyphon

In this paper, a computational fluid dynamics model is developed to simulate the working state of a two-phase closed thermosyphon (TPCT). Two-phase volume model volume of fluid (VOF) and Lee model were used to simulate the heat transfer process of evaporation and condensation in the TPCT. The boiling and condensation heat transfer of TPCT were investigated numerically with water as working fluid. The internal local wall temperatures were measured at a filling rate of 0.5 to determine the heat transfer variations based on the transverse and longitudinal positions. The results show that the numerical model can simulate the phase transition process well. The temperature distribution in evaporating section is uniform. The temperature in condensing section and adiabatic section decreases with the increase of height in vertical direction. The temperature in horizontal direction is lower. The heat transfer mechanism of the TPCT was analysed under certain operating conditions. (paper)