Ceramic Miniature Heat Pipes and Liquid Charging Methods

Abstract

Three working-liquid charging methods for miniature heat pipes are introduced, and their advantages and disadvantages are described. The methods are referred to as the micro-syringe method, thermodynamic equilibrium method, and capillary-tubing method. Using these methods, two types of ceramic heat pipes were charged and tested. The ceramic heat pipes were made of alumina and have overall dimensions of 89 mm × 12 mm × 2.9 mm and a designed vapor space of 82.5 mm × 4.1 mm × 1.27 mm. Axial micro-capillary grooves were provided on the top and bottom or sidewalls inside the heat pipes as wick structures. Water was used as the working liquid. More than 20 W of heat input was achieved on a 5 mm × 5 mm heating surface. The corresponding heat flux was 80 W/cm2.