On the Validity of Onsager Reciprocal Relations (ORR) for Heat Transfer in Anisotropic Solids

In this work, we investigate the validity of axioms such as Onsager Reciprocal Relations (ORR) for heat transfer in irreversible thermodynamics close to equilibrium. We show that ORR case could be directly derived by introducing widely accepted concept coefficients into entropy production rate and assuming thermal conductivity are uniquely defined. It is believed work can not only used pedagogical purposes but may also generalized other processes beyond transfer, thus leading a framework transport phenomena thermodynamics.