Muthanna Journal of Engineering and Technology
Volume (14), Issue (2), Year (2026), Pages (63-76)
DOI:10.52113/3/eng/mjet/2026-14-02-/63-76
Research Article By:
Nadhum H. Safir, Malek Khalaf Albzeirat, Kadhim H. Suffer
Corresponding author E-mail: kadhim.h.suffer@nahrainuniv.edu.iq
ABSTRACT
Thermosyphon heat pipes are highly effective two-phase thermal transport devices widely used in electronics cooling, solar energy systems, and battery thermal management. This study presents a numerical investigation of the thermal performance of a thermosyphon heat pipe using ANSYS Fluent with a VOF (Volume of Fluid) two-phase model. The simulation considers temperature distribution, phase interactions, and equivalent thermal resistance under varying fill ratios, tube diameters, and heat flux conditions. The results show that an optimum fill ratio of 70% minimizes thermal resistance, while deviations increase it by 18–25%. Tubes with smaller diameters have 12% lower thermal resistance to large diameter tubes because of increased vapor velocity and enhanced heat transfer. A 20 percent increase in the height of the liquid-column increases the resistance to heat transfer, and a 50 percent increase in the rate of heat transfer decreases it by 15 percent. The fill ratio, tube size and heat flux affect start-up times to steady-state operation by 25-40 percent with the higher heat fluctuation accelerating stabilization by 35 percent. The results of this quantitative study size up the interdependence of geometric and operating parameters on thermosyphon performance. The paper offers a model of optimization of the design to determine the best choice of tube size, fill ratio, and heat injection to obtain the best heat transfer efficiency.
Keywords:
Thermosyphon, Heat Pipe, Two-Phase Flow, Numerical Simulation, Thermal Resistance, Heat Transfer Optimization.