Question

Please use Google Scholar and search for the fourth mode of heat transfer, this paper was published on Nature in 2019. So try your best to find this paper and read it. Summarize this paper in one or two paragraphs.

Answer 1

Heat transfer proceeds by three modes: Conduction, Convection and radiation. Conduction transfers heat by direct molecular collision. Convection differs in that heat transfer depends on the properties of the fluid adjacent the material surface. Unlike conduction and convection, heat transfer by thermal radiation does not necessarily need a material medium for the energy transfer. However, heat transfer may also proceed by a fourth mode. Like convection altering the surface of the material, the fourth mode of heat transfer requires coating the surface of the material with a nanoscale layer of a material having a higher refractive index. Unlike conduction, radiation, and convection that find basis in classical physics, the fourth mode is based on quantum mechanics with the heat transferred to the surroundings by electromagnetic radiation. Classical physics that requires the atom to always have heat capacity does not predict any heat transfer enhancement for nanoscale coatings. But quantum mechanics by requiring the heat capacity of the atom in nanoscale coatings to vanish prevent the conservation of electromagnetic energy by the usual increase in temperature. Instead, the heat into the coating under electromagnetic confinement is induced by quantum electrodynamics (QED) to create non-thermal electromagnetic radiation that produces excitons (hole and electron pairs) that upon recombination ionize and charge the coating or emit the electromagnetic radiation to the surroundings.

Quantum electrodynamics induced non-thermal electromagnetic radiation based on quantum mechanics is proposed as the 4th mode of heat transfer alongside classical modes of conduction, radiation, and convection. At the macroscale, conduction is thought to be the most efficient mode of heat transfer at ambient temperature with thermal radiation becoming important at elevated temperatures and convection relatively negligible. But at the nanoscale, the lack of heat capacity precludes the temperature `changes necessary for thermal conduction. What this means is conduction does not exist at the nanoscale and the Fourier equation is no longer applicable.

Applications of quantum electrodynamics heat transfer for thin films, nanoelectronics, and turbine blades suggest that environmental fouling may limit the efficiency of nanocoatings for turbine blades. But thin films and nanoelectronics in clean environments should greatly enhance heat removal.

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