Radiative Heat Transfer in Real Surfaces

This lecture covers the laws of Kirchoff, defining the conditions for establishing relationships for emissivity and absorptivity. It explains the spectral hemispherical emissivity and total hemispherical emissivity, emphasizing the impact of real surfaces on radiative heat transfer. The lecture also discusses the net radiation exchange at surfaces, providing an electrical analogy for understanding the energy transfer. Various empirical correlations for external free convection flows are presented, along with boundary layer similarity solutions and equations. The content includes examples of heat transfer calculations in different scenarios, such as condensation on brass tubes and cooling of electrical transformers.