Design and preliminary experiments of a novel heat pipe using a spiral coil as capillary wick

Abstract

Axial-grooved ammonia-aluminum heat pipes are the most commonly used heat pipes for spacecraft thermal management today. The axial-groove piping manufacturing requires special die manufacturing and extrusion techniques, which limits its availability to academic research and industrial applications. In this research, we propose a new heat pipe structure, replacing the conventional axial-grooved or sintered wicks with spiral coil and simple piping container. The proposed heat pipe structure is introduced thereby for its design and operational mechanism. Two test articles were fabricated. Preliminary experiments were carried out to investigate the heat transfer performance with different wire diameters and compare with a charged container without coil wick. To further verify its applicability to spacecraft engineering, an axial-grooved heat pipe of comparable cross-sectional area was also tested for comparison. The experimental data are presented and analyzed for heat pipe axial temperature profiles, transient behavior, evaporation/condensation film coefficients, and effective thermal conductivity. The study showed that the new wick structure is a viable and low-cost alternative to the current axial-grooved heat pipes for spacecraft thermal control systems. Its wick-container separation design also enables heat pipe integrations with the spacecraft structural components and easy fabrication of mini heat pipes.