Optical method for measuring the temperature distribution in hot glass melts

Abstract

In the present study a technique is developed to determine temperature profiles in hot glass melts, using intensity measurements performed at various wavelengths in the infrared spectrum. To that end an analytical model is developed which describes the internal energy transfer in a glass layer and the spectral intensity emerging from the glass layer. The so calculated spectral intensity is confronted with a measured spectral intensity to reconstruct the temperature profile in the glass layer. Because the temperature reconstruction from the measured spectral intensity is an ill-posed inverse problem, Tikhonov regularization and the L-curve method are used to determine a meaningful temperature distribution in the glass layer. In order to investigate the usefulness of the temperature reconstruction method an experimental setup is built. Measurements are performed for various temperature gradients, glass depths and glass types. The temperature difference over the glass depth measured by a thermocouple minus that measured by the optical method is, on average, of the order of 2 K.