Temperature measurement near the triple line during phase change using thermochromic liquid crystal thermography

The temperature generated by the evaporation of a volatile liquid in a confined space (tube ∅=1,630 μm) was mapped onto the tube surface with the use of unsealed thermochromic liquid crystals (TLCs). The strong evaporative cooling effect located near the meniscus triple line generates a temperature dip. Despite the thermal diffusion through the tube’s thickness and its geometry, the TLC thickness and the inherent difficulties of working with unsealed TLCs, the present technique has revealed to be a suitable tool for accurate temperature measurement at the microscale size. The evaporation flux is deduced from the profile of temperature and comparison with the experimental measurement shows a very good agreement. The role of the nature and thickness of the tube wall material on the diffusion of the temperature profile from the inside to the outside is also investigated.