Entropy generation equilibrium thermodynamics

The ideal, unrealistic, but basic limit of the thermodynamic efficiency of a process is that of the reversible process where all work available and entering the process is still available after the process. Work has simply been transferred from one carrier to another. Driving forces are infinitesimally small and the process is "frictionless" no barriers have to be taken. As a result, there is neither entropy generation nor loss of available work. The work requirements of the process can be accurately calculated from the thermodynamic properties of the equilibrium states that the process passes through. 

The theory treating near-equilibrium phenomena is called the linear nonequilibrium thermodynamics. It is based on the local equilibrium assumption in the system and phenomenological equations that linearly relate forces and flows of the processes of interest. Application of classical thermodynamics to nonequilibrium systems is valid for systems not too far from equilibrium. This condition does not prove excessively restrictive as many systems and phenomena can be found within the vicinity of equilibrium. Therefore equations for property changes between equilibrium states, such as the Gibbs relationship, can be utilized to express the entropy generation in nonequilibrium systems in terms of variables that are used in the transport and rate processes. The second law analysis determines the thermodynamic optimality of a physical process by determining the rate of entropy generation due to the irreversible process in the system for a required task. 

An Open System does exchange matter and energy with the surroundings. Thermodynamically, it does not tend to the thermodynamic equilibrium, but to the steady state or what should be called the stationary non equilibrium state, characterized by minimum entropy generation. An example is a continuous stirred tank reactor. 

Entropy generation is considered a key concept of nonequiHbrium thermodynamics. Let us view entropy generation for the following cases isolated systems, systems in a homogeneous thermostat, and systems in a nonhomogeneous environment (in the temperature gradient field, in chemical potential field, etc.). At that, let us divide systems into two types weakly nonequilibrium (linear) and far from equilibrium (nonlinear). 

As mentioned before, nonequilibrium thermodynamics could be used to study the entropy generated by an irreversible process (Prigogine, 1945, 1947). The concept ofhnear nonequilibrium thermodynamics is that when the system is close to equilibrium, the hnear relationship can be obtained between the flux and the driving force (Demirel and Sandler, 2004 Lu et al, 2011). Based on our previous linear nonequihbrium thermodynamic studies on the dissolution and crystallization kinetics of potassium inorganic compounds (Ji et al, 2010 Liu et al, 2009 Lu et al, 2011), the nonequihbrium thermodynamic model of CO2 absorption and desorption kinetics by ILs could be studied. Figure 17 shows the schematic diagram of CO2 absorption kinetic process by ILs. In our work, the surface reaction mass transport rate and diffusion mass transport rate were described using the Hnear nonequihbrium thermodynamic theory. 

Because the configurational entropy of interstitial defects has the same form as that of vacancies, a population of self-interstitial atoms is also thermodynamically stable. The creation of these defects can then also be treated as a pseudochemical equilibrium, and an equation for the relationship between the number of self-interstitials and the appropriate equilibrium constant for interstitial generation, Kv is readily... 

The thermodynamic spontaneity of the interacalation process is determined by an interplay of entropic and enthalpic factors [38, 39]. The confinement of the polymer inside the interlayer results a decrease in the overall entropy of the polymer chains. However, the entropic penalty may be compensated by the increased conformational freedom of the tethered surfactant chains in a less confined environment, as the layers separate out. Even then, there is an overall decrease in entropic factor as the increase in gallery height is very small. Thus the degree of layer separation depends on the establishment of very favorable polymer surface interaction to over come the penalty of polymer confinement. There are two different types of interactions, unfavorable apolar interaction and the favorable polar interaction, which originates from the Lewis acid/Lewis base character of the layered silicates. Thus depending on the interactions and entropic factors three possible equilibrium states are generated namely immiscible (conventional), intercalated and exfoliated. 

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