Heat Flux Manipulation with Engineered Thermal Materials

Utilizing a multilayered composite approach, we have designed and constructed a new class of artificial materials for thermal conduction. We show that an engineered material can be utilized to control the diffusive heat flow in ways inconceivable with naturally occurring materials. By shielding, concentrating, and inverting heat current, we experimentally demonstrate the unique potential and the utility of guiding heat flux.

Figure 1

(a) A block of material is placed between two heat baths. (b) Concept of thermal shielding by flux manipulation. (c) Concept of concentrating thermal flux. (d) Concept of inverting thermal flux.

Figure 2

(a) Anisotropic thermal shield. The schematic shows a cut section for clarity. (b) Cross-sectional schematic for multilayered thermal concentrator. (c) Cross-sectional schematic for multilayered composite designed to invert the applied heat flux. (d) Close-up view of the inverter showing the constitutive materials.

Figure 3

(a) Simulated temperature profile for a hollow copper cylinder placed in agar-water block. (b) Simulated heat flux lines. (c) Experimentally measured temperature map for the copper case. (d) Simulated temperature profile for a hollow polyurethane cylinder placed in agar-water block. (e) Simulated heat flux lines. (f) Experimentally measured temperature map for the polyurethane case. (g) Simulated temperature profile for a multilayered shield placed in agar-water block. (h) Simulated heat flux lines. (i) Experimentally measured temperature map for the reported shield. For the experimental data, dotted lines outline the inner and outer radii of shield materials. Left and right bars show the contrast scales for simulation and experimental images, respectively.

Figure 4

(a) Simulated temperature profile for a concentrator placed in agar-water block. (b) Simulated heat flux lines. (c) Experimentally measured temperature map for the reported concentrator. Temperature scales are the same as those used in Fig. 3. We note the existence of the left-right asymmetry in the temperature profile in the experimental data and speculate that it may be due to the unequal layering of the materials employed.

Figure 5

(a) Simulated temperature profile for the reported device. (b) Simulated heat flux lines. The device’s inner structures are not shown for the flux density plot for clarity. Arrows are guides to the eye to indicate flux direction.

Figure 6

(a) Experimentally measured thermal image showing the rotation of thermal gradient. Dotted lines outline the inner and outer diameters of the reported material. (b) Isothermal line for $20.3–20.7°\mathrm{C}$.