Experimental investigation and visualization on capillary and boiling limits of micro-grooves made by different processes

Micro-grooves with various feature sizes ranged form 200 to 500 μm were fabricated as micro-wick structures by two different processes, including chemical etching and precision milling, for the experimental investigation and visualization on capillary and boiling limits. Pure water was employed as the working fluid, and the surfaces of the micro-wick structures were cleaned to ensure the hydrophile and the same surface conditions of these samples before testing. Various heat fluxes were then applied to these micro-wick structures to measure their thermal performances and capillary and boiling limits by both temperature measurement and experimental visualization. In addition, the experimental results were compared with the simplified analytical models. This study proposes a simple method to determine working limits and thermal performance of micro-structures for designing wick and selecting process.