Analysis of thermal irreversibilities in a homogeneous and isotropic solid

This research study focuses its attention on the local and temporal distribution of the entropy production generated by thermal irreversibilities as well as on the fact that they contribute, together with the entropy flow through the frontier, towards raising the solid entropy, under situations of thermal transient. For simplicity, a simple unidimensional model, the semi-infinite solid, for which several solutions depending on the Fourier equation time are well known, is investigated; they are here discussed with respect to their aspects of second principle. Moreover, it should be noticed that both entropy and entropy production are not linear in temperature. The principle of superposition is, therefore, not valid for them; this gets the remarks expounded in this paper to be considered as an exemplification of the entropic problems in simple cases, rather than a method for working out entropic solutions in more complex cases.