Indium tin oxide coated transparent surfaces for the study of nucleateboiling

Abstract

This paper explains how to use indium tin oxide (ITO) coated glass to providetransparent heated surfaces with sufficient heat fluxes to generate nucleate boilingin water. The technique enables extended surfaces that exhibit nucleate boiling tobe analysed using novel optical diagnostic methods. The results from theseoptical experiments are presented.In the experiments, a horizontal glasssubstrate coated with an ITO layer on its top surface was immersed indemineralized water with temperatures between 70 and 80°C.A direct electrical current was passed through the ITO layerto heat the water at heat fluxes of 65 to 110 kW m−2.The resulting nucleate pool boiling from the ITO surface was analysedusing a high-speed imaging system comprising an infrared laser and CCDcamera. Data on bubble size and nucleation site density were obtained.Additionally, image-processing software allowed the void fraction to bedetermined, representing an advance over previous measurement techniques.