Heat flux cloaking, focusing, and reversal in ultra-thin composites considering conduction-convection effects

Abstract

Experimental results are presented for heat flux cloaking, focusing, and reversal in ultra-thin anisotropic composites. A two-material system is utilized in the device design, which features an annular region for heat flow control. The effective thermal conductivity layout of the composite is specified through logical combination of the base material constituents. Heat transfer considering conduction-convection is numerically predicted and experimentally verified via infrared thermography. A Biot number analysis reveals the significance of high rates of convection for large-area planar devices, while the experimental results indicate the feasibility of such heat flow control techniques for advanced electronics applications involving natural convection.

Collection of low-grade waste heat for enhanced energy harvesting

“…As explained in Ref. 13, dual (i.e. conduction plus convection) heat flow mechanisms are important, and higher rates of forced convection reduce the heat focusing effect.…”

“…18, this triple function of the design suggests a synergy between the various traits of the three types of fundamental heat flux manipulation devices studied in Ref. 13 for optimal end effect. This specific result also resembles the Sensu-shaped thermal metamaterial structure designed for uniform heating in Ref.…”

“…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.…”

Directional heat transport through thermal reflection meta-device

“…1, [8][9][10] With thermal metamaterials, many new heat transfer phenomena have been reported, like cloaking, concentrating, rotating, inversing, thermal diode, camouflage, illusion, lens, etc. [11][12][13][14][15][16][17][18][19] An intuitive question thus arises that whether we could realize the directional heat transport through thermal metamaterials.…”

Engineering the accurate distortion of an object’s temperature-distribution signature

“…In 2008, Fan et al [2] first adopted the coordinate transformation approach to propose a class of thermal metamaterials with novel thermal properties a email: jphuang@fudan.edu.cn that cannot be found in nature or chemical compound; their work provides a different way to steer heat conduction. As a result, a lot of thermal metamaterials with novel thermal properties have come to appear, such as cloaks (which are used to let heat flow around an object as if the object does not exist) [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18], concentrators (which are used to concentrate heat into a specific region) [4,5], inverters (which are used to apparently let heat flow from the region of low temperature to the region of high temperature) [2,19], and rotators (which are used to rotate the flow of heat as if it comes from a different angle) [5,19].…”