ARTICLE:

• EFFECT OF THE SPECTRAL RADIATIVE PROPERTIES ON THE ANNEALING OF OPTICAL QUALITY GLASS  download article

Kong Hoon Lee
School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-1288, USA

Raymond Viskanta
Purdue University

ABSTRACT

Transient combined conduction and radiation heat transfer is analyzed in optical quality glass disks. The effect of the spectral optical properties on the annealing (i.e., controlled cooling) of optical quality glass are studied by considering different glasses having greatly different spectral absorption coefficients. In the study, the spectral dependence of the absorption coefficient on wavelength is appropriately accounted for by solving the radiative transfer equation for the axisymmetric cylindrical geometry. Specularly reflecting boundaries are considered and Fresnel's equations are used to predict the spectral directional reflection and transmission characteristics of the interfaces. The finite volume method is used to solve numerically the thermal energy equation, and discrete ordinates method (DOM, S-N method) is employed to solve the radiative transfer equation (RTE). The numerical calculations have been carried out for both radiation and combined convection and radiation cooling from the surfaces. Transient temperature distributions, temperature gradients, convective and combined convective plus radiation results are presented and discussed.

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