Showing papers by "Daniel Tondeur published in 1987"
TL;DR: In this article, a propriete for thermodynamique de non-equilibre classique: relations lineaires flux-force and relations de reciprocite d'Onsager.
Abstract: Dans un dispositif de contact ou de separation comprenant une aire de transfert donnee et effectuant un transfert specifie, l'entropie totale produite est minimale lorsque la vitesse locale de production d'entropie est uniformement repartie (equiseparee) le long des variables spatiales et/ou temporelles. Cette propriete est demontree pour les conditions de thermodynamique de non-equilibre classique: relations lineaires flux-force et relations de reciprocite d'Onsager. On montre que les procedes «equisepares» sont optimaux au sens economique, c'est-a-dire qu'ils correspondent au minimum de quelque fonction de cout
214 citations
TL;DR: In this article, the authors generalized the traveling wave approach to multicomponent systems, with particular concern for adsorption, electrophoresis, and diffusion, and conjectured that the same qualitative trends should hold for all systems where several species compete for a limited resource or space, according to a definite hierarchy.
Abstract: The travelling wave approach to some unsteady transfer processes, developed for ‘one-component’ systems in Part I ( Chem. Eng. Process., 21 (1987) 167–178), is generalized to multicomponent systems, with particular concern for adsorption, electrophoresis, and diffusion. For systems in which a given order of ‘mobility’ or ‘competitiveness’ of the components exists, the multicomponent waves obey a set of relatively simple and general qualitative rules of behaviour. These rules govern, in particular, the number of distinct waves generated by a step perturbation, the concentration changes of the components relative to one another in each wave, and the spreading or sharpening tendency of these waves. This ‘competitive’ behaviour is shown to be related to the structure of the matrix coupling the conservation equations of the components, and especially to the orientation of its eigenvectors in the space of concentrations. On the basis of this analysis, a profound mathematical and also physical analogy is shown between fixed-bed Langmuir adsorption, electrophoresis with constant relative mobility, and Stefan-Maxwell diffusion. It is conjectured that, beyond the special form of the equilibrium or transfer laws considered above, the same qualitative trends should hold for all systems where several species compete for a limited resource or space, according to a definite hierarchy, a given order of competitiveness.
15 citations
TL;DR: In this article, the authors analyse non-linear unsteady processes, as different as car traffic, adsorption, sedimentation, packed-bed heat transfer and hydraulic waves, using the concept of the travelling wave.
Abstract: Non-linear unsteady processes, as different as car traffic, adsorption, sedimentation, packed-bed heat transfer and hydraulic waves, can be analysed in a unified fashion by using the concept of the travelling wave. The fundamental aspects of the ‘solitary’ waves are discussed, as well as their distinctive features, such as overall and local propagation velocities, shape modifications, appearance of shocks, and ‘coherent’ asymptotic shape. These features are governed by the velocity distribution along the wave, itself determined by the relationship between the flux and the concentration variables of the process. Qualitative rules result from the analysis of ‘operating lines’ and ‘equilibrium lines’ in the flux versus concentration diagram, in a way somewhat similar to the McCabe-Thiele analysis for steady counter-current operations.
12 citations