Radiative Properties of Surfaces: Heat Transfer Fundamentals

This lecture covers the fundamental concepts of radiative heat transfer, focusing on the properties of surfaces. The instructor begins by discussing the importance of understanding intensity, emissive power, irradiation, and radiosity, which are essential variables in heat transfer. The lecture emphasizes the relationship between these variables and how they can be integrated to determine heat flux. The instructor introduces the concept of black body emissive power and its dependence on temperature and wavelength, explaining how to non-dimensionalize the curves for better analysis. The discussion then shifts to surface radiative properties, including emissivity, absorptivity, and reflectivity, detailing their definitions and how they relate to energy transfer. The instructor explains the assumptions of local thermodynamic equilibrium and Kirchhoff's law, which connects absorptivity and emissivity. The lecture concludes with examples and applications of these concepts in practical scenarios, preparing students for future analyses of energy transfer in enclosures with varying surface properties.