Modeling the phase change process for a two-phase closed thermosyphon by considering transient mass transfer time relaxation parameter

The method with minimal errors considering transient mass transfer time relaxation parameter for the phase change process is proposed in this study. A model coupled Volume of Fluid (VOF) model, phase change model and continuum surface force model is developed to simulate heat transfer characteristics and phase change process for a two-phase closed thermosyphon. The mass transfer process is implemented by adding User Define Function (UDF) to FLUENT code. The results obtained from this study show that the model with transient mass transfer time relaxation parameter has smaller relative errors (0.27-0.73%) for absolute temperature distributions along the wall of a two-phase closed thermosyphon than the model without transient mass transfer time relaxation parameter (2.01-2.97%). The model with transient mass transfer time relaxation parameter has smaller relative errors for the thermal resistances at evaporation and condensation sections (3.21-4.23% and 2.45-6.78%) than the model without transient mass transfer time relaxation parameter (18.31-21.74% and 15.34-28.25%), respectively. The model developed in this study can also detail the phase change process and therefore can be used to predict heat performance better for different types of heat pipes. (C) 2016 Elsevier Ltd. All rights reserved.