An Experimental and Analytical Study of Radiative and Conductive Heat Transfer in Molten Glass

One-dimensional temperature profiles and heat fluxes within a slab of molten glass were measured experimentally. The glass slab was contained between two parallel platinum-lined ceramic plates. The plate temperatures were kept above 2000 deg F so that radiation heat flux was always equal to or larger than conduction. An optical method of temperature measurement was developed in which a helium–neon laser beam was directed along an isothermal path through the glass. The attenuation of the beam was a strong function of temperature and was used to evaluate the local temperatures within the glass slab. In order to perform a theoretical analysis the spectral absorption coefficient of the glass was measured from 2000 to 2300 deg F. Two analyses were performed: one for a diffuse platinum–glass boundary and the other for a specular boundary. The calculated temperatures agree with the measured values within 5 deg F throughout the slab, and the measured and predicted heat fluxes agree within 10 percent.