Transport phenomena irreversible processes

The product of thermodynamic forces and fiows yields the rate of entropy production in an irreversible process. The Gouy-Stodola theorem states that the lost available energy (work) is directly proportional to the entropy production in a nonequilibrium phenomenon. Transport phenomena and chemical reactions are nonequilibrium phenomena and are irreversible processes. Thermodynamics, fiuid mechanics, heat and mass transfer, kinetics, material properties, constraints, and geometry are required to establish the relationships... 

The Seebeck effect corresponds to the electricity production from a difference of temperature. This effect can be reversible and is the inverse of the Peltier effect, which is the phenomenon of conversion of electric energy into thermal energy (heat). These effects can be superimposed onto the dissipative processes of transport by conduction of electric charges (Joule effect) and to the transport of heat (Fourier equation) which are both irreversible processes. 

Sevastianov et al.73,74) have developed a model which considers the effect of surface heterogeniety on the adsorption process. They define centers of irreversible adsorption , labeled P, and centers of irreversible desorption , labeled D. They argue, in agreement with Soderquist and Walton, that desorbed material is conformationally altered and thus cannot readsorb — hence desorption is irreversible. The results of this model are given as Fig. 14, taken from Ref. 7J). The model also includes the case where adsorption may be transport limited. The model fits commonly observed adsorption data, including the overshoot phenomenon (Fig. 14, top) (discussed in Ref. 72)) to be discussed later. 

The general phenomenon of polymer adsorption/retention is discussed in some detail in Chapter 5. In that chapter, the various mechanisms of polymer retention in porous media were reviewed, including surface adsorption, retention/trapping mechanisms and hydrodynamic retention. This section is more concerned with the inclusion of the appropriate mathematical terms in the transport equation and their effects on dynamic displacement effluent profiles, rather than the details of the basic adsorption/retention mechanisms. However, important considerations such as whether the retention is reversible or irreversible, whether the adsorption isotherm is linear or non-linear and whether the process is taken to be at equilibrium or not are of more concern here. These considerations dictate how the transport equations are solved (either analytically or numerically) and how they should be applied to given experimental effluent profile data. 

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