Modeling of Heat Pipes in Steady-State and the Effects of Sloshing
D. Kural (TU Delft - Mechanical Engineering)
L. Botto – Mentor (TU Delft - Complex Fluid Processing)
R.A.J. van Ostayen – Graduation committee member (TU Delft - Mechatronic Systems Design)
E. Zanetti – Graduation committee member (TU Delft - Heat Transformation Technology)
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Abstract
This MSc thesis investigates the performance of a sintered-powder wick copper-water heat pipe by focusing on two primary areas: a hypothetical exploration of the inner dynamics under high-acceleration conditions, specifically the effects of sloshing, and the detailed mathematical & computational modeling of its steady-state operation. The effects of a sloshing motion were analyzed through a series of analytical ”thought experiments.”
These investigations defined and modeled potential phenomena, including, but not limited to, pressure-induced liquid ”leakout” from the wick and the re-wetting of the undersaturated wick. A 2D axisymmetric computational model of the heat pipe was also developed in COMSOL Multiphysics for simulating steady-state operation. The model solves the coupled equations for heat transfer and fluid flow, accounting for the solid casing, the liquid-saturated porous wick, and the compressible vapor core. The dynamic analysis revealed that under high accelerations, significant wick dryness can occur, with its severity being highly dependent on wick permeability. Furthermore, the theoretical results indicate that the leaked liquid can shorten the re-wetting period of the wick, possibly leading to a rapid recovery of thermal performance. The steady-state computational model was also successfully validated against existing literature, demonstrating accurate predictions of temperature, pressure, and velocity profiles. The study successfully provides a validated steady-state model and a preliminary mathematical framework for understanding the complex physics of sloshing in heat pipes. While the final objective of coupling the dynamic and steady-state models was not achieved, this work lays the critical groundwork for future transient multiphysics simulations of heat pipes.