Application of high-speed IR thermography to study boiling of liquids

Abstract

A method for studying local and integral characteristics of heat transfer at pool boiling on a thinfilm heater using a high-speed thermal-imaging camera is described. Experiments have been carried out at pool boiling of saturated ethanol with a heat flux as high as 40 W/cm². A 1-μm-thick indium−tin oxide (ITO) film sputtered on a 0.4-mm-thick sapphire substrate by the vapor deposition method was used as a heater. Based on simultaneous measurements of the temperature field distribution at the back side of the ITO film using an IR thermal-imaging camera in combination with visual recording of vapor bubble growth and departure directly on the heater surface, it is possible to judge the temperature field evolution under individual vapor bubbles, the nucleation site density and the nucleation frequency, as well as the time of bubble growth and departure during boiling.