Mechanical relations between conductive and radiative heat transfer

TL;DR

This paper develops a unified theoretical framework using nonequilibrium Green's functions to model coupled conductive and radiative heat transfer, especially relevant at nanoscales and atomic separations.

Contribution

It introduces a formalism that captures the interplay of conduction and radiation, extending existing models to systems where both phenomena are significant.

Findings

Predicted heat transfer in low-dimensional systems differs from simple additive models.

Established algebraic relationships between phonon and radiative conduction.

Highlighted importance of coupled descriptions at nanometric scales.

Abstract

We present a general nonequilibrium Green's function formalism for modeling heat transfer in systems characterized by linear response that establishes the formal algebraic relationships between phonon and radiative conduction, and reveals how upper bounds for the former can also be applied to the latter. We also propose an extension of this formalism to treat systems susceptible to the interplay of conductive and radiative heat transfer, which becomes relevant in atomic systems and at nanometric and smaller separations where theoretical descriptions which treat each phenomenon separately may be insufficient. We illustrate the need for such coupled descriptions by providing predictions for a low-dimensional system of carbyne wires in which the total heat transfer can differ from the sum of its radiative and conductive contributions. Our framework has ramifications for understanding heat transfer between large bodies that may approach direct contact with each other or that may be coupled by atomic, molecular, or interfacial film junctions.