Redlich-Kwong EOS

The last term, the fluid s isothermal compressibility, can be reasonably predicted from a two-parameter, cubic equation of state (EOS) such as the Redlich-Kwong EOS or the Peng-Robinson EOS.(14,15) The fluid s isothermal compressibility was determined using the Redlich-Kwong EOS to evaluate the derivative ( Vmmob/3P) in eq. 12 due to the ease of finding an analytical solution,... 

The second term on the RHS of eq. 22 is the volume expansivity which can be calculated from a two-parameter, cubic equation of state such as the Redlich-Kwong EOS.(14) We chose the Redlich-Kwong EOS because the "a" term is independent of temperature, which simplifies the procedure of solving for the analytical solution. Using the method of implicit differentiation with the Redlich-Kwong equation of state,... 

Firstly, we will examine the VLE of binary mixtures. The Wilson model is selected for liquid activity with Redlich-Kwong EOS for vapor phase. The predictions offered by Aspen Plus [9] are in agreement with experimental data [5], except... 

Figure 3. Glucose K-factors (xL2/xL1) from VLLE measurements in the glucose+acetone+ water+carbon dioxide system against system temperature and pressure. ( = experimental data, grid = calculation results with Soave-Redlich-Kwong EOS, see text)...

Phase compositions of VLLE in the systems glucose + acetone + water + carbon dioxide and carbohydrates + 2-propanol + water + carbon dioxide have been determined experimentally. Like for VLE of related systems from literature, the carbohydrate solubility in a phase rises when the phase becomes more similar to the water-rich lower liquid phase. At the same time separation of different carbohydrates becomes more difficult because selectivity decreases. Theoretically based models can help to find an optimum of capacity and selectivity and to minimize the number of necessary experiments. A simple model based on the Soave-Redlich-Kwong EOS which can reproduce glucose partitioning between the two liquid phases in VLLE in the glucose + acetone + water + carbon dioxide system is presented. 2-Propanol is shown to be a better modifier for these systems than acetone, but denaturation of carbohydrates in the carbohydrate + 2-propanol + water + carbon dioxide system limits industrial applications. 

The fugacity coefficient can be calculated using a suitable EOS. The Soave—Redlich—Kwong EOS (SRK EOS) will be employed in this paper. Starting from the SRK EOS... 

Find the implicit vapor pressure equation of the Redlich-Kwong eos. The RK eos, Equation (4.153), will be written in a simplified form. 

In the Chao-Seader correlation, the fugacity coefficient in the gas mixture is obtained from the Redlich-Kwong eos and is as follows ... 

Problem 4.41 Soave-Redlich Kwong EOS with MATHCAD... 

Using a Mathcad program forihe Soave-Redlich-Kwong EOS we find 7/(300° C, 25 bar) = 9.45596x 103 J/mol... 

Much later Soave (1972) proposed a new modification, known as Soave-Redlich-Kwong EOS, abbreviated here SRK-EOS, in which the model incorporates another important molecular parameter, the acentric factor co(see later the equation 5.12). The result was that the accuracy of VLE computations improved considerably. In the case of SRK-EOS the alpha function is ... 

The UNIQUAC model [14] was used to account for liquid phase non-idealities. The vapor phase was modeled using the Redlich-Kwong EOS ]15]. The combination of both is implemented in Aspen Plus as the UNIQ-RK property model. UNIQUAC... 

In which a is the molecular parameter of the Redlich-Kwong eos [15] for the adsorbate in the gas phase. 

Similarly, the assumption that g(r) is independent of volume and temperature is also restrictive, and Vera and Prausnitz demonstrate how relaxing this assumption can lead, for example, to the Redlich-Kwong EoS. 

Turning to molecular attractions, the molecular dynamics results of Alder et al (1972) indicate that, even the simple square-well interaction potential, leads to a much more complex expression for the attractive term, than those used in the van der Waals and Redlich-Kwong EoS. 

Develop the Soave-Redlich-Kwong EoS starting with Eq. 17.9.1. (For guidance, see Vera and Prausnitz.). 

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