Tunable Heat-Flux Rectification in Graded Nanowires in Non-Linear Guyer-Krumhansl Regime

Abstract

We study heat rectification in composition-graded nanowires, with nonlocal and nonlinear effects taken into account in a generalized Guyer-Krumhansl equation. Using a thermal conductivity dependent on composition and temperature, the heat equation is solved. Introducing a non-vanishing heat supply (as for instance, a lateral radiative heat supply), we explore the conditions under which either nonlocal or nonlinear effects or both contribute to heat rectification and how they may be controlled by means of the external radiative flux. The corresponding rectification coefficients are calculated as well, and the physical conditions under which the system becomes a thermal diode are pointed out.

Thermodynamics of Composition Graded Thermoelastic Solids

“…Such a property can be used to optimize their performances in several applications [3]. For example, at nanoscale, graded alloys of type Si c Ge 1−c with the stoichimetric variable c ∈ [0; 1] changing along a given direction are used in the design of thermal diodes [4][5][6][7][8][9][10] or to enhance the efficiency of thermoelectric energy conversion [11,12]. Graduation can be also induced by the anisotropic dependency of the properties of the material on spatial gradients of some thermodynamic variables, since a spatial gradient in the microstructure along a certain direction results in changes in the local material properties.…”