Detecting thermal rectification

Abstract

Thermal rectification is a special heat transfer phenomenon that thermal conductance of a sample is higher in one direction than that in the reversed direction. Thermal rectifiers have been proposed to be the building blocks of phononic circuits, high performance thermoelectric devices, and energy-saving materials. Theoretically, thermal rectification has been suggested to be ubiquitous, occurring in wherever nonlinear interactions and broken inversion symmetry are present. However, currently available experimental methods have limited sensitivities and are unable to unravel the interesting effect in many systems. Here, by adopting the concept of nonlinear optics, we propose an improved experimental method to detect minuscule thermal rectification from large background thermal conductance. Experimentally, a SiC nanowire, a SiGe nanowire, and a multiwall BN nanotube are investigated and found their thermal rectification is smaller than 0.2% even after asymmetric mass-loading. The method would be very powerful in revealing interesting phonon properties of many materials.

Thermal rectification optimization in nanoporous Si using Monte Carlo simulations

“…At φ = 18% the pores are uniformly distributed throughout the simulation domain and no rectification is observed. Thus, structural asymmetry in the transport direction (x-direction) gives rise to thermal rectification as also observed in previous theoretical [16,17,20] and experimental works [30,31]. In Fig.…”

“…Recently, significant research has been done on understanding and controlling phonon transport in nanostructures for novel materials and applications [1][2][3][4][5][6][7][8]. Since initial findings of thermal rectification between Cu and Cu2O [9] interfaces in the 1930s, various experimental [10][11][12] and theoretical [13][14][15][16][17][18][19][20][21] studies have investigated thermal rectification in different materials. Rectification values of up to 350% were theoretically predicted in graphene nanoribbons [22], while experiments showed that graphene junctions could provide even higher values of up to 800% rectification [12].…”

“…Rectification values of up to 350% were theoretically predicted in graphene nanoribbons [22], while experiments showed that graphene junctions could provide even higher values of up to 800% rectification [12]. In the more technologically placed silicon, theoretical studies suggest that geometrically asymmetric structures can enhance thermal rectification effects [14][15][16][17][18][19], verified by some experimental works as well [10,15,23]. Rectification is achieved when the structure is separated into regions in which the mean-free-path (MFP) is controlled by two mechanismsthe temperature-dependent Umklapp scattering, and a mechanism much less temperature dependent such as boundary scattering.…”

Thermal rectification in restructured graphene with locally modulated temperature dependence of thermal conductivity

“…Enhancement for Q + /Qhas been commonly considered by introducing a structural asymmetry in the system yielding an asymmetric phonon transport. Till date, mass-loading [6][7][8], nanostructure embedded interface [9,10], and shape asymmetric tapered (tailored) nanomaterials [10][11][12][13][14][15][16] and networks [17] have been studied so far. Measured γ TR values are mostly less than 40% and usually smaller than theoretical predictions (references are therein Ref.…”

Thermoelectric and electron heat rectification properties of quantum dot superlattice nanowire arrays

“…Because Q e,B is insensitive to the variation of ∆T , the behavior of R r is very similar to Q e,F . To design HDs, one needs to have a high R r at a small temperature bias [39]. Fig.…”