2-D and 3-D modulated porous coatings for enhanced pool boiling

A new fabrication method (hot-powder compaction) is developed to readily make 2-D and 3-D modulated coatings for enhanced pool-boiling performance. The modulated coatings are 2-D and 3-D stacks with different height, width, and pitch (modulation wavelength), and made with different particle diameters and porosities. The maximum measured critical heat flux image of 2-D and 3-D modulated coatings are 3.3 and 2.0 times that of the surface without coatings (plain). As expected from the hydrodynamic stability theory, the experimental results for 2-D coatings are similar to 3-D coatings and show that image strongly depends on the modulation wavelength, while particle diameter and porosity have a little effects. The results also suggest that a stack aspect ratio (height to pitch) larger than unity is needed for modulation enhancement of the critical heat flux.