Improved Heat Removal by Microscopic Surface Texturing of Capillaries

Phase I demonstrated that ion beam microtexturing of metal surfaces enhances heat transfer under three conditions: (1) thermal radiation emission at relatively high temperatures, (2) forced convection, and (3) nucleate boiling. Features were too small to significantly affect heat transfer under non-flowing constant phase conditions. For nucleate boiling, combining microtexture with large scale structures, and after optimizing the texturing process, it should be possible to achieve a composite enhancement better than 20 times the nucleate- boiling heat transfer from a smooth surface. Ion texturing processes produce rugged broadband light absorbers, completely black from the visible to long wavelength IR. At higher temperature ranges, enhanced radiation adds significantly to total heat transferred. Thus, heat pipes, capillaries, and higher temperature radiators would all perform better with microtextured surfaces.