Study on the heat transfer mechanism in nucleate pool boiling of water by measuring local heat flux and temperature

Abstract

An experimental work is undertaken to obtain the local temperature and heat flux information on the boiling surface during the saturated pool boiling of water. Using IR thermometry, the temperature distribution can be measured when mid-wave (3-5.5$\mu m$) optical access to the surface is possible. In addition, the heat flux can be calculated by the heat conduction equation with this temperature information. The contact line length density (CLD) and the characteristics of the time-averaged wetted area fraction (WF) are observed for an IR opaque indium-tin-oxide surface over an electrically heated silicon substrate which is transparent to IR. With this information, the dominant heat transfer mechanism during the pool boiling of water is evaluated. The results are observed in various heat flux regions and compared to those with different working fluids, in this case FC-72, for which the properties (contact angle, latent heat of vaporization, liquid thermal conductivity, and critical heat flux) are quite different from those of water. In conclusion, convection heat transfer on the liquid area based on the micro-convection model is the predominant heat transfer mechanism during the nucleate pool boiling of water.