Microscale Temperature Measurements Near the Triple Line of an Evaporating Thin Liquid Film

Thin-film evaporation from a meniscus in a confined space, which is the basis for many two-phase cooling devices, is experimentally investigated. The meniscus formed by heptane, a highly wetting liquid, on a heated fused quartz wafer is studied. Microscale infrared temperature measurements performed near the thin-film region of the evaporating meniscus reveal the temperature suppression caused by the intensive evaporation in this region. The high spatial resolution (∼6.3 μm) and high temperature sensitivity (∼20 mK) of the infrared camera allow for improved accuracy in the measurements. The effects of evaporation rate, applied heat flux, and channel width on the thin-film heat transfer distribution are also explored.