Search results for "Volume balance"
showing 2 items of 2 documents
Transport equations of electrodiffusion processes in the laboratory reference frame.
2006
The transport equations of electrodiffusion processes use three reference frames for defining the fluxes: Fick's reference in diffusion, solvent-fixed reference in transference numbers, and laboratory fluxes in electric conductivity. The convenience of using only one reference frame is analyzed here from the point of view of the thermodynamics of irreversible processes. A relation between the fluxes of ions and solvent and the electric current density is deduced first from a mass and volume balance. This is then used to show that (i) the laboratory and Fick's diffusion coefficients are identical and (ii) the transference numbers of both the solvent and the ion in the laboratory reference fr…
Transport coefficients in desalting processes by electrodialysis
2011
Abstract In this work a thermodynamic analysis on the transport equations in the processes of electrodiffusion (EF) and electrodialysis (ED) has been developed. The transport equations are classified in two sets according to the information they contain: i ) fundamental and ii ) complementary. We determine that there are four fundamental transport coefficients needed to characterize these membrane systems. We also conclude that this number is not reduced to three when the Onsager reciprocal relation (ORR) is assumed. I have also obtained a new expression for the concentration rate in EF and ED processes from the mass and volume balance. This relation provides a new way for evaluating the ap…