Natural convection heat transfer of the low Prandtl number fluid with solidified layer formation

Experimental and analytical studies have been performed on natural convection heat transfer in the low Prandtl number fluid of the molten metal with a rapid solidified layer formation. The experimental results on the relationship between the Nusselt number and Rayleigh number were compared with the existing correlations. The temperature distribution and the heat transfer rate have been evaluated using the numerical model. The experimental study has shown that a solidified layer formation leads to a decrease of natural convection heat transfer rate in the metal pool, due to the solidified layer's action as a conducting thermal barrier. The experimental results are more similar to Globe and Dropkin's correlation than any others. Even though the Rayleigh number rapidly decreases due to an increase of the solidified layer thickness, the Nusselt number does not rapidly decrease because of the aspect ratio effect. The numerical results on the temperature profile and the heat transfer rate in the metal pool region match well with the experimental data. (C) 1998 Elsevier Science Ltd