Capillary penetration of highly volatile liquids in a paper strip: an experimental study on wicking, evaporation, and condensation

The wicking phenomenon has gained more interest in research due to its vast applications in electronic cooling, spacecraft, etc. In this work, we aim to comprehend the impact of phase change due to evaporation on surface tension driven wicking in a model porous media. An experimental investigation of evaporation of highly volatile liquids (n-Pentane, Acetone, and Ethanol) was carried out on a thin and flat rectangular filter paper of varying average pore sizes ranging between 2.5 and 30 μm. This study presents transient as well as steady state behavior of liquids rising on vertical porous strips exposed to the ambient laboratory conditions. A novel aspect of this study is to determine the capillary penetration and simultaneous evaporation. For this purpose, surface temperature is measured using an infrared camera. It was observed that the lower the latent heat of vaporization, the higher the rate of evaporation and the lower the surface temperature. The influence of evaporation on wicking also depends on the average pore size of the porous media. This study finds its relevance in electronic cooling devices and thermal management.