Journal of the American Ceramic Society, Vol.84, No.10, 2296-2302, 2001
Theoretical investigation of heat transfer in glass forming
A theoretical study to investigate internal heat transfer in glass undergoing cooling between glass and mold, as well as plunger, during and after pressing, is described. A thermal model has been formulated to simulate the cooling. The heat-transfer analysis accounts for the spectral nature of radiation in glass, the dependence of the thermophysical properties of glass on temperature, and the contact heat transfer between and after pressing, as well as subsequent cooling. Heat exchange between glass and mold by contact conduction across a very small gap and that by thermal radiation are considered separately. Numerical solutions have been obtained for typical conditions simulating symmetric and nonsymmetric cooling, and the results obtained are presented and discussed. During the dwell time, thermal-contact conduction between glass and mold is the dominant mechanism for heat extraction from glass. Results show that radiation from the surface of the glass plays a relatively small role in the beat extraction from the glass, but that radiation from the interior of the glass is much more significant.