P. Ben-Abdallah

We quantitatively analyze the thermal emission by anisothermal structures. By comparing the heat flux radiated by simple multilayered systems calculated using the classical Kirchhoff's law to the exact flux derived from a fluctuational-electrodynamics theory, we highlight the limits of validity of the radiometric theory to predict the thermal emission with respect to the geometric configuration, the temperature gradient, and the type of materials and also highlight discrepancies as high as 50%.

In the classical approach to dealing with near-field radiative heat exchange between two closely spaced bodies, no coupling between the different heat carriers inside the materials and thermal photons is usually considered. Here, we provide an overview of the current state of research on this coupling between solids of different sizes while paying specific attention to the impact of the conduction regime inside the solids on the conduction–radiation coupling. We describe how the shape of the solids affects this coupling, and show that it can be located at the origin of a drastic change in the temperature profiles inside each body and the heat flux exchanged between them. These results could have important implications in the fields of nanoscale thermal management, near-field solid-state cooling, and nanoscale energy conversion.