Volume 31, Issue 1

For the first time, numerical simulations of mass transfer for real flow conditions have been made in a wavy liquid film falling down a vertical wall. Hydrodynamical parameters have been calculated by solving the Kapitsa-Shkadov system with a semi-parabolic velocity profile. Calculations have been performed with natural waves and forced waves. Optimal frequencies of forced inlet disturbances that enhance the mass transfer have been found along with the main mechanisms of the mass transfer. The calculated mass absorption has been compared with experimental data and a good agreement was obtained.

Relativistic irreversible thermodynamics is reformulated following the conventional approach proposed by Meixner in the non-relativistic case. Clear separation between mechanical and non-mechanical energy fluxes is made. The resulting equations for the entropy production and the local internal energy have the same structure as the non-relativistic ones. Assuming linear constitutive laws, it is shown that consistency is obtained both with the laws of thermodynamics and causality.

The relation between the topology of a chemical reaction network and its thermodynamic properties, particularly the energy dissipation patterns, is analyzed. Both regular and complex structures are considered. For networks consisting of linear reactions, this task is analytically accomplished by formulating the network dynamics in terms of the network's connectivity matrix. The thermodynamic effect of nonlinear feedback dynamics on chemical networks is considered in the limits of close to and far away from equilibrium and discussed in connection with the robustness of the response to external disturbances.

In this paper, by combining the PC-SAFT equation of state (EOS) to the thermal diffusion models for non-associating mixtures, the theoretical prediction of thermal diffusion has been carried out for associating fluid mixtures including water–methanol, water–ethanol, and water–isopropanol. At first, the parameters of the PC-SAFT for water–methanol, water–ethanol, and water–isopropanol mixtures are optimized. Then, by comparing the predictive and experimental values of density and residual partial molar enthalpy in water–methanol, water–ethanol, and water–isopropanol mixtures, we demonstrate the capability of PC-SAFT EOS to reproduce reliable thermodynamic properties in these mixtures with a low to moderate water concentration. Finally, with the thermodynamic properties from the PC-SAFT, several thermal diffusion models available in the literature are extended to binary water–alcohol mixtures including water–methanol, water–ethanol, and water–isopropanol. The Firoozabadi model combined with the PC-SAFT EOS has shown an effective capability for predicting mixtures with a low to moderate water concentration.

A simplified crystallization model is developed with emphasis on situations of disparate specific volumes of the solid and liquid phases. Using the general equation for the nonequilibrium reversible-irreversible coupling (GENERIC), the model is formulated in terms of the average momentum density, the degree of crystallinity, a single temperature, and a single pressure, where in particular the latter two are appealing for comparison with experiments. In order to describe the volume expansion upon crystallization, a dissipative mass current density is introduced, for which a constitutive relation is derived. One finds that by way of the Onsager–Casimir symmetry, the introduction of this irreversible current also leads to a modification of the driving force for phase change. Rather than depending only on the local chemical potential difference, it also contains a non-local term, namely the Laplacian of the ratio of pressure p to temperature T , multiplied by the square of a screening length. The model is studied for the specific case of aluminum, for which a perturbation analysis is performed. The results show that the type and rate of relaxation of a perturbation depend strongly on its wavelength and on the screening length.