Theoretical realization of an ultra-efficient thermal-energy harvesting cell made of natural materials

Abstract

Controlling electromagnetic energy is essential for an efficient and sustainable society. A key requirement is concentrating magnetic energy in a desired volume of space in order to either extract the energy to produce work or store it. Metamaterials have opened new possibilities for controlling electromagnetic energy [1,2]. Recently, a superconductor-ferromagnetic metamaterial that allows unprecedented concentration and amplification of magnetic energy, and also its transmission at distance through free space, has been devised theoretically [3]. Here we design and build an actual version of the superconductor-ferromagnetic metamaterial and experimentally confirm these properties. We show that also a ferromagnetic metamaterial, without superconducting parts, can achieve concentration and transmission of energy with only a slight decrease in the performance. Transmission of magnetic energy at a distance by magnetic metamaterials may provide new ways of enhancing wireless power transmission, where efficiency depends critically on the magnetic coupling strength between source and receiver.

A transient thermal cloak experimentally realized through a rescaled diffusion equation with anisotropic thermal diffusivity

“…[1][2][3][4][5][6][7][8] The TO technique has also led to the creation of many other important EM devices with functionalities previously deemed impossible or unconceivable. [9][10][11] In general, this coordinate operation can be applied to different partial differential equations governing the behaviors of other physical phenomena such as thermal flux, [12][13][14][15][16][17][18][19][20][21][22][23] acoustic wave, [24][25][26][27] and matter or quantum [28][29][30] waves, demonstrating important scientific and application potentials.…”

“…33 Later, these discussions led to the use of coordinate transformation to manipulate heat conduction. 12,13 However, most of the previous discussions or thermal devices have been proposed by applying coordinate transformation to the thermostatic heat conduction equation, [12][13][14][19][20][21] , that is,r Á (kru) ¼ 0, with k representing the thermal conductivity and u representing the temperature field. This approach limits the transformed devices to work only in a thermostatic state.…”

Diffusive-light invisibility cloak for transient illumination

“…Conversely, the thermal analogs of the considered diffusive cloaks would only demand an engineered diffusivity. It is worth mentioning that there exist alternative cloaking techniques that can also relax the implementation complexity of thermal cloaks [34,35], as well as of dc current cloaks [36].…”

Collection of low-grade waste heat for enhanced energy harvesting

“…Harvesting thermal energy through heat flux manipulation and focusing has been proposed by researchers as a practical extension of work on thermal metamaterials [1][2][3][4][5] and has practical applications for autonomously powered sensors 6 or self-actuated devices. 7,8 Heat flux focusing is one manner in which heat flow may be controlled, [2][3][4][5]9,10 and different effects, such as heat flux cloaking or reversal, have also been demonstrated theoretically 9,11 and experimentally for thick devices, 10 planar structures, 12,13 and three-dimensional objects.…”

“…7,8 Heat flux focusing is one manner in which heat flow may be controlled, [2][3][4][5]9,10 and different effects, such as heat flux cloaking or reversal, have also been demonstrated theoretically 9,11 and experimentally for thick devices, 10 planar structures, 12,13 and three-dimensional objects. 14 Recently, thermoelectric devices have also been applied to facilitate the manipulation of heat flow for an active thermal cloak around arbitrarily shaped regions.…”