Heat radiation and transfer in confinement

TL;DR

This paper investigates how confinement by additional objects affects near-field heat radiation and transfer, revealing significant modifications and resonances in heat exchange and radiation due to geometrical constraints.

Contribution

It provides detailed calculations of heat transfer and radiation in confined geometries, highlighting how confinement can amplify or suppress heat exchange and radiation effects.

Findings

Confinement alters heat transfer, leading to slower decay with distance.

Heat radiation can be significantly enhanced or suppressed inside cavities.

Resonances cause large variations in cooling rates depending on cavity size.

Abstract

Near-field heat radiation and transfer are rich in various exciting effects, in particular, regarding the amplification due to the geometrical configuration of the system. In this paper, we study heat exchange in situations where the objects are confined by additional objects so that the dimensionality of heat flow is reduced. In particular, we compute the heat transfer for spherical point particles placed between two parallel plates. The presence of the plates can enhance or reduce the transfer compared to the free case and provides a slower power-law decay for large distance. We also compute the heat radiation of a sphere placed inside a spherical cavity, finding that it can be larger or smaller compared to the radiation of a free sphere. This radiation shows strong resonances as a function of the cavity's size. For example, the cooling rate of a nanosphere placed in a cavity varies by a factor of $10^5$ between cavity radii $ 2 \ \mu {\rm m} $ and $ 5 \ \mu {\rm m} $.