Numerical analysis of flow characteristics and bubble behavior inside a two-phase closed thermosyphon under various temperature difference

In the present work, a two-dimensional axisymmetric two-phase closed thermosyphon model (TPCT) filled with refrigerant R-134a is developed based on the volume of fluid method, Lee model, and continuum surface force model in the Fluent to simulate the two-phase flow characteristics and bubble behaviors inside the TPCT. The effects of increasing the temperature difference (ΔT) between the evaporator and condenser on the inner wall temperature, liquid film distribution and bubble growth process are highlighted. The results show that at different ΔT and FR, the inner wall temperature of the evaporator section increases and then decreases in inhomogeneity with increasing temperature difference at 0.5 and 0.75 FR, while at 0.05 and 0.25 FR, almost uniform inhomogeneity is observed. Bubble behavior is varied and affected by different ΔT at 0.75 FR, the comprehensive bubble incubation and growth is achieved by observing video.