No abstract

No abstract

ResumenSe aplica un modelo para el cálculo de la viscosidad del tipo ecuación cúbica de estado de Peng-Robinson. El modelo ha sido empleado para correlacionar y predecir viscosidades de sustancias puras y mezclas en especial en la región de saturación. Los parámetros del modelo han sido generalizados en términos de la masa molar. Las expresiones generalizadas son estimadas mediante el ajuste de datos experimentales de alcanos y alcoholes. Las desviaciones absolutas promedio para la viscosidad, entre los valores correlacionados y los experimentales, son 6.26% y 7.21% para alcanos y alcoholes, respectivamente. Se realizan cálculos predictivos con desviaciones absolutas promedio de 3.99% para alcanos y 13.76% para alcoholes. Para viscosidades de mezclas se utilizaron tres enfoques de reglas de mezclado. Las desviaciones promedio calculadas son 18.66%, 10.31% y 3.85% para las reglas simples, de uno y dos parámetros respectivamente. Los resultados indican que el modelo propuesto proporciona resultados adecuados y consistentes, teniendo en cuenta la simplicidad de las expresiones generalizadas desarrolladas. Palabras clave: viscosidad; ecuaciones cúbicas de estado; sustancias puras; mezclas Modeling the Viscosity Based on Peng-Robinson Type Cubic TP Equation AbstractA viscosity model based on the Peng-Robinson cubic equation of state is applied. The model has been used to correlate and predict viscosities of pure substances and mixtures especially in the saturation zone. The parameters of the model are generalized in terms of the molar mass. The generalized expressions are estimated by fitting the experimental data for a group of alkanes and alcohols. Average deviations between calculated values and experimental data for alkanes and alcohols are 6.26% and 7.21%. Some predictive calculations are performed for alkanes and alcohols finding average absolute deviation of 3.99% and 13.76%. To extend the model to mixtures, some binary mixtures calculations are performed using three mixing rule approaches. The results obtained with the simple, one and two interaction parameters mixing rules are 18.66%, 10.31% and 3.85%. The results indicate that the new viscosity model provides results that can be considered adequate and consistent taking in account the simplicity of the generalized expressions.

No abstract

In this work, a model for the thermal conductivity of nonpolar and polar substances is developed based on the geometric similitude concept between the P−v (molar volume)−-T and T−k (thermal conductivity)−-P plots. The Redlich−Kwong equation of state is used to perform the geometric similitude. The parameters of the model are estimated by fitting experimental data of saturated liquid and saturated vapor. Generalized expressions in terms of the normal boiling point are proposed for the parameters of n-alkanes and n-alcohols. The calculated average absolute deviations are 7.63 and 8.55%, respectively, for the n-alkanes and the n-alcohols used to develop the generalized expressions. Also, some predictive calculations are performed, and deviations below 10.62 and 9.42% are obtained for n-alkanes and n-alcohols, respectively. In total, 2412 experimental data (952 correlated data and 1460 predicted data) in the temperature range of 95− to 645.5 K and pressures below 906.4 bar have been considered. The empirical model has been extended to binary and ternary mixtures using several approaches. In total, 16 mixtures in the temperature range between 287.55 and 345.48 K at 1.01 bar are evaluated. The deviations are below 4.63% when one binary interaction parameter is used. In general, the results indicate that the empirical model is simpler than the other models reported in the literature and generates adequate results.