Three-dimensional hydrodynamic and thermal modeling of a flat grooved heatpipe using three different formulation

Mathematical modeling of the grooved heat pipes is a challenging task since various phys- ical phenomenon such as phase change, free-surface flow and heat transfer are involved. Moreover, the fact that the shape of the liquid-vapor interface is unknown a priori, the shape of the interface needs to be determines as a part of the solution procedure, a ca- pability currently not addressed in commercially available engineering CFD software. In this study, a multi-dimensional and multi-scale computational model is presented to gain comprehensive understanding of underlying psychics of the grooved heat pipes. The com- putational model is based on an iterative scheme for the solution with 3-D heat transfer and liquid flow, interface phase change heat transfer (evaporation and condensation) and the shape of the interface. The model is implemented using three different methodologies: (i) a finite difference based formulation of the heat transfer with a unidirectional fluid flow coupled to the phase-change models; (ii) a finite element based formulation with multi- dimensional heat transfer and fluid flow through COMSOL Multiphysic and coupled to phase-change models models through COMSO -MATLA interface; and (iii) a finite volume based formulation with multi-dimensional heat transfer and fluid flow through ANSYS FLUEN with a PYTHONTM based main driver for the coupling of the phase changer models and the generation of the computational domain through a CAD software. The workflows of the three methodologies are demonstrated and the underlying reasons of the differences between the solution methodologies, advantages and disadvantages of proposed methodologies are discussed.