IR measurements of interfacial temperature during phase change in a confined environment

The temperature profile generated by differential evaporative cooling along the meniscus interface of volatile liquids in capillary tubes ranging from 600 to 1.630 mum is measured by the use of an IR camera. The great spatial resolution of the camera (similar to30 mum) and its sensitivity (20 mK at 30 degreesC) allowed us to capture the sink effect at the meniscus triple line where most of the evaporation takes place. The results clearly show that the sink effect increases with the reduction of the tube size and the use of more volatile liquids. We also demonstrated that the convection resulting from the self-induced evaporative cooling, affects the temperature profile along the meniscus interface. The practical difficulties in accessing to temperature measurements at the micro-scale are well recognized. The strong evaporation near the meniscus triple line is a key factor in many industrial applications such as heat pipes and crystal growth involving phase change. (C) 2004 Elsevier Inc. All rights reserved.