Thermal Rectification Using Bulk Materials

In conduction, thermal rectification occurs when a material or structure transfers heat asymmetrically. In this work, it is shown that, in the bulk, the necessary condition for thermal rectification is that the thermal conductivity of the material or structure be a function of both space and temperature, and that this function is not separable. Practically, this can be achieved using a composite structure consisting of many materials, though it could also be achieved with a properly developed single material. Nomenclature A(x) Spatially-dependent thermal conductivity function. C Integration constant. k Thermal conductivity. L Length. q Heat rate. Corresponding author: Address: Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA; phone:574-631-8394 fax: 574-631-8341; e-mail: [email protected] e-mail:[email protected] 1 R Rectification factor. T Temperature. x One-dimensional coordinate. α Temperature-dependent thermal conductivity coefficient. θ Temperature difference relative to the reference temperature T0. λ(T ) Temperature-dependent thermal conductivity function.