DOI: 10.1615/ICHMT.1995.RadTransfProc
ISBN Print: 978-1-56700-068-9
ISSN Online: 2642-5629
ISSN Flash Drive: 2642-5661
SPECTRORADIOMETRIC STUDY OF THE SURFACE POLLUTION INFLUENCE ON THE RADIATIVE PROPERTIES OF ROLLING STEEL SHEETS. APPLICATION TO ONTINUOUS ANNEALING FURNACES
ABSTRACT
The purpose of this research is to study the surface pollution influence on the radiative properties of rolled steel sheets. The surface pollution resulting from rolling operations is a mixture of oils and thin particles of iron and is similar to a semitransparent medium. This residual film modifies the infrared absorption of the iron sheet and its heating kinetics during its thermal treatment within the continuous annealing furnace.
We elaborated a model to derive the radiative transfer in an isothermal semitransparent medium, for a one-dimensional geometry. This model uses the discrete ordinates method which offers the advantage to take into account the high anisotropy of the radiative properties at the interfaces. This model describes precisely the physical phenomena due to the pollution on the sheet metal.
We developed an experimental device to measure the directional spectral emissivity of the sheets under industrial thermal treatment conditions. This device is composed of a spectroradiometer and an annealing simulator. It allows to heat the samples up to a temperature of one thousand degrees Celsius and to determine the radiative properties in a spectral range between two to fourteen micrometers. The emissivity measurements were also obtained under industrial heating kinetic. The calculations are in good agreement with the emissivity measurement.