Analysis of entropy generation of combined heat and mass transfer in internal and external flows with the assumption of local thermodynamic equilibrium

Abstract

In this paper, the control volume method is used to establish the general expression of entropy generation due to combined convective heat and mass transfer in internal and external fluid streams. The expression accounts for irreversibilities due to the presence of heat transfer across a finite temperature difference, mass transfer across a finite difference in the chemical potential of a species, and due to flow friction. Based on the assumption of local thermodynamic equilibrium, the generalized form of the Gibbs equation is used in this analysis. The results are applied to two fundamental problems of forced convection heat and mass transfer in internal and external flows. After minimizing the entropy generation, useful conclusions are derived that are typical of the second law viewpoint for the definition of the optimum operation conditions for the specified applications, which is a valuable criterion for optimum design of heat and fluid flow devices.