Thermal and Flow Simulation of Concentric Annular Heat Pipe with Symmetric or Asymmetric Condenser

Abstract

The current research work describes the flow and thermal analysis inside the circular flow region of an annular heat pipe with a working fluid, using computational fluid dynamics (CFD) simulation. A two-phase flow involving simultaneous evaporation and condensation phenomena in a concentric annular heat pipe (CAHP) is modeled. To simulate the interaction between these phases, the volume of fluid (VOF) technique is used. The temperature profile predicted using computational fluid dynamics (CFD) in the CAHP was compared with previously obtained experimental results. Two-dimensional and three-dimensional simulations were carried out, in order to verify the usefulness of 3D modeling. Our goal was to compute the flow characteristics, temperature distribution, and velocity field inside the CAHP. Depending on the shape of the annular heat pipe, the thermal performance can be improved through the optimal design of components, such as the inner width of the annular heat pipe, the location of the condensation part, and the amount of working fluid. To evaluate the thermal performance of a CAHP, a numerical simulation of a 50 mm long stainless steel CAHP (1.1 and 1.3 in diameter ratio and fixed inner tube diameter (78 mm)) was done, which was identical to the experimental system. In the simulated analysis results, similar results to the experiment were obtained, and it was confirmed that the heat dissipation was higher than that of the existing conventional heat pipe, where the heat transfer performance was improved when the asymmetric area was cooled. Moreover, the simulation results were validated using the experimental results. The 3-D simulation shows good agreement with the experimental results to a reasonable degree.

Numerical Model of Heat Pipes as an Optimization Method of Heat Exchangers

“…In turn, Zhang and co-authors in [11] proposed an innovative design with dense ribs of less thickness in the upper layer and relatively low ribs of greater thickness in the lower layer to further improve the overall thermal efficiency of a two-layer microchannel heat exchanger; the numerical model was based on similar equations presented in this publication. In the works on numerical modeling [12][13][14][15], the authors use numerical models to optimize heat exchangers, both traditional and heat pipes, and obtain results similar to the results obtained in this publication. Rossome and Ochman, together with their co-authors in [16,17], study numerical processes of heat exchange in thermal energy stores.…”

Thermal Investigations of Hemispherical Shell Vapor Chamber Heat Sink

“…We ran numerical analyses under a variety of situations using the ANSYS FLUENT 2020 R2 program. To compare the simulated and experimentally derived temperatures, the analysis focused on the following circumstances and assumptions [52,59].…”

“…The governing equations in the simulation involved continuity, mass conservation, and momentum equations based on the Navier-Stokes principle, as follows [52,60]:…”

“…Several heat pipes [45][46][47][48][49][50][51][52] were subjected to numerical analysis. The volume of fluid (VOF) methodology, which is one of the most well-known methods, was used in their computational fluid dynamics to simulate the two-phase flow of liquid-vapor phases.…”

“…This is induced by a long calculation time. Song et al [52] tried to simulate annular heat pipes numerically using the VOF model. Song et al showed that 3D simulation agrees well with the experimental results compared with 2D simulation.…”