On the Positivity of Entropy Production in Multiphase Thermodynamic Systems

Abstract

Abstract Multiphase processes are frequently assumed to evolve restricted by thermodynamic equilibrium relations. In this article, we study the possibility of multiphase systems to evolve far from thermodynamic equilibrium while contained in what we call a domain of physical feasibility. We show that processes evolving in the domain of feasibility have a positive definite internal entropy production rate. Being positive definite, the internal entropy production stands as a Lyapunov function candidate to characterize the stability of equilibrium for irreversible multiphase systems contained in the feasibility domain. In addition, the thermodynamic-based approach considered in our study provides phenomenological insight into the dynamic properties of multiphase systems. Counter-flow interface molar transport processes, for instance, are found to be thermodynamically stable provided that the transport is bounded by a function that depends on the deviation from thermodynamic equilibrium.