THE MODELING OF RADIATION HEAT-TRANSFER IN FOREHEARTHS UNITS IN GLASSMELTING

The interaction between conduction, convection and radiation heat tran sfer in molten glass has been studied with specific reference to the f orehearth units of a glass tank furnace. In shallow molten glass flows as typically encountered in forehearth units, the radiation-conductiv ity approach for modelling the radiative transfer process is found ina ppropriate. This is especially so for colourless glasses which are not optically thick below 2.8 microns. In the present work radiative heat transfer process in molten glass has been treated more rigourously by incorporating both optically thick and thin limits. The radiative int eraction at the boundaries is treated more realistically. In the case of colourless glasses, the results obtained by the present method show the necessacity to account for the direct radiative interaction betwe en the interior layers of the glass and refractory walls at the top an d the bottom. The forehearth exit temperature profiles obtained by usi ng the present method are quite different with those obtained using th e radiation conductivity approach.