Transient heating of opaque and semitransparent materials by radiation during processing

Abstract

Analysis is presented of transient heating of opaque and semitransparent (translucent) materials by external radiation sources. Such problems arise in materials processing and manufacturing applications. Dynamic temperature distributions are calculated in a plate (slab) of material by accounting for spectral nature of the radiation source and the radiative properties of the material. Effects of radiation properties influenced by the choice of material to be heated, chemical and mechanical treatment, radiation source temperature, and convective heat transfer are considered. Differences in temperature response of opaque and semitransparent materials are examined. It is shown that the temperature distribution in a semitransparent material heated by an external radiation source is more uniform than in an opaque material for otherwise the same conditions owing to the “long range” transport of radiation. Treatment of a semitransparent material as opaque results in an unrealistic prediction of temperature distribution when the material is heated by an infrared radiation source.