Effect of nano-structure coating on thermal performance of thermosyphon boiling in micro-channels

A novel micro-channel thermosyphon technology for passively cooling 3D stacked chips was provided, and the thermosyphon boiling characteristics in vertical and inclined micro-channels with two open ends which simulate the specific stacked structure of actual 3D chip were experimentally carried out. In order to improve the heat transfer of micro-channel thermosyphon by surface treatment technology, four kinds of nanoparticles (CuO, Cu, Al2O3, SiO) were added to the base fluid to make nano-structure coatings on the heater surfaces by using a long time pool boiling treatment. Then, micro-channel thermosyphon boiling experiments were carried out with four kinds of working liquids: two kinds of pure fluids (deionized water and R113) and two kinds of moist fluids (deionized water+surfactant and R113+surfactant). The gaps and heights of micro-channels tested were in the range of 30-60 μm and 30-90 mm, respectively. Experimental results show that nano-structure coatings can significantly enhance both the maximum heat flux and heat transfer coefficient of thermosyphon boiling in micro-channels, and exist both the optimal nanoparticle kind and nanoparticle concentration in the base fluids. The experimental results provided some meaningful technology support for 3D stacked chip cooling.