Natural convection heat transfer with crust formation in the molten metal pool

An experimental study has been performance natural convection heat transfer ,with and without crust formation in a molten metal pool. Two types of stea dy-state tests, natural and forced convection coolings of the molten metal pool were performed in low- and high-aspect-ratio cases. When the natural c onvection flow is developed in the molten metal pool, the overlying coolant conditions do not affect the crust formation. On the other hand when the n atural convection flow is not det eloped, the coolant conditions affect the crust formation. The heat transfer rate of cases,with crust formation is l ower than that of cases without crust formation due to the effect of the cr ust serving as a thermal barrier. The present experimental results on the r elationship between the Nusselt number and Rayleigh number match better wit h Globe mid Dropkin's correlation than arty others. with an increase in the crust thickness, the Nusselt number in the metal pool does not rapidly dec rease in spite of a rapid decrease ill Rayleigh number because the aspect r atio of the metal pool decreases. A new correlation between the Nusselt num ber and Rayleigh number in the molten metal pool with crust formation has b een del eloped as Nu = 0.0923 (Ra)(0.302) (2 X 10(4) < Ra < 2 X 10(7)).