Search

The experimental data of vapor–liquid equilibrium for the binary systems methyl acetate + 1–propanol, methyl acetate + 1–butanol and ethyl acetate + 1–propanol at 1.5 MPa has been obtained, using an ebulliometer made of stainless steel. This equipment works through the Cottrell pump effect, so that the liquid and vapor phases are recirculated. The isobaric data T–x–y are informed and analyzed with respect to the literature data. The evolution of the azeotropic point with the pressure in the binary system of ethyl acetate + 1–propanol is included. The thermodynamic consistency of the systems was verified by employing the Peng–Robinson equation of state in different forms and using the φ–φ approach.

Highlights • Carbon dioxide + propane mixtures are studied through accurate measurements of speeds of sound and phase equilibria. • Heat capacities and virial coefficients are obtained from speeds of sound. • Retrograde condensation zone is found for the (0.60 CO2 + 0.40 C3H8) mixture. • Results are compared with reference equations of state such as GERG-2008 and AGA8-DC92. This work presents phase envelope and speed of sound data for the (0.60 CO2 + 0.40 C3H8) and (0.80 CO2 + 0.20 C3H8) binary mixtures. Phase equilibria was measured using a cylindrical resonator working in the microwave band whereas an acoustic resonator was used for speed of sound measurements. The experimental results were compared with GERG-2008 equation of state, obtaining average absolute deviations by 0.24% in pressure for phase equilibria data and 0.025% for speed of sound data. Speed of sound values were used to derive perfect-gas heat capacities, acoustic virial coefficients, and second density virial coefficients. In addition, AGA8-DC92 equation of state performance was checked for the results derived from speeds of sound.

El trabajo de investigación desarrollado en esta Tesis Doctoral ha sido el diseño y puesta en marcha de una nueva cavidad cilíndrica resonante en microondas con un tubo de zafiro situado en el eje central de la cavidad que contendrá la muestra a analizar, para la determinación del equilibrio de fases a alta presión de sustancias presentes en el biogás y el gas natural. La validación del equipo se ha llevado a cabo mediante la determinación de la curva de vaporización del CO2, comparando los resultados obtenidos mediante la ecuación de estado de Span & Wagner. Además, se han medido la envolvente de fases de las mezclas binarias formadas por CO2+CH4; CO2+C3H8 y CO2+N2 a diferentes composiciones en CO2. Estas mezclas además de ser comparadas con la literatura existente, se han estudiado mediante la ecuación de estado GERG-2008, comparando las desviaciones obtenidas experimentalmente con los devueltos por medio de esta ecuación. Además, se ha empleado la ecuación de estado de Peng-Robinson, por medio de las reglas de mezclas de Wong & Sandler con el propósito de obtener los coeficientes de ajuste de dicha ecuación y evaluar el ajuste obtenido con las mezclas estudiadas., Departamento de Ingeniería Energética y Fluidomecánica, Doctorado en Investigación en Ingeniería Termodinámica de Fluidos

The vapor–liquid equilibrium of binary mixtures of propyl acetate, butyl acetate and isobutyl acetate with methanol has been determined at a constant pressure of 0.6 MPa. Results have been modeled with the Peng–Robinson equation, a traditional cubic equation of state widely employed in chemical industries, as well as with the perturbed-chain statistical associating fluid PC-SAFT theory of Gross–Sadowski. By correlation of the binary interaction parameters of these equations, the measured vapor–liquid equilibrium data can be accurately predicted. Thus, this work shows that these models are able to represent the experimental data for systems with associating compounds via hydrogen bonding.

We report viscosities of liquid hexadecane measured at temperatures between 323 K and 673 K and at pressures up to 4.0 MPa. This study significantly extends the temperature range over which viscosity data for hexadecane are available. The experiments were carried out using a dual-capillary viscometer that measures the ratio of the viscosity at the temperature in question to that at a reference temperature, 298.15 K in this work, at which the viscosity is well known. Absolute viscosities were then obtained with an estimated expanded relative uncertainty of about 3% at 95% confidence. An empirical function was developed to correlate the viscosity ratio with the density ratio and this fitted the experimental data within about 1%. The results were found to agree well with the existing literature data.

Producción Científica, The development of a novel technique based on a cylindrical microwave resonator for high pressure phase equilibrium determination is described. Electric permittivity or dielectric constant is a physical property that depends on temperature and pressure ε(p,T). Based on this property, a measuring technique consisting of a cylindrical resonant cavity that works in the microwave spectrum has been developed. Equilibrium data of fluid mixtures are measured at high pressure using a synthetic method, where phase transition is determined under isothermal conditions due to the change of the dielectric constant. This technique may be a more accurate alternative to conventional visual synthetic methods. The technique was validated measuring pure CO2, and phase behaviour was then determined for two binary mixtures [CO2 (0.6) + CH4 (0.4)] and [CO2 (0.4) + CH4 (0.6)], results for which are presented. These systems are interesting for the study of biogas–like mixtures. In addition, data were compared with the equation of state used for natural gas GERG-2008, and also, they were modelled using Peng-Robinson equation of state and Wong- Sandler mixing rules, which are widely employed in chemical industries and which give good results., Trabajo financiado por el Ministerio de Industria, Economía y Competitividad (ENENE2013-47812-R y ENE2017-88474-R) y la Junta de Castilla y León (VA035U16 y VA280P18)

Vapor–liquid equilibrium data for the binary systems methyl acetate + 2-butanol and ethyl acetate+2-butanol, have been determined at 1.5 MPa employing a metal ebulliometer with recirculation of both phases. The thermodynamic consistency of experimental data has been verified with the Van Ness point-to-point test, using the routine in Fortran proposed by Fredenslund et al. in which the second and third virial coefficients were calculated using the Tsonopoulos method and the Orbey and Vera procedure, respectively. Different group contribution models were employed for prediction of high pressure data. The UNIFAC–Lyngby model returned good overall predictions. The ϕ–ϕ approach was applied using the perturbed-chain statistical associating fluid theory model. This equation of state produces an acceptable agreement between experimental and calculated data in both systems.

Isobaric vapor–liquid equilibrium data for the binary systems methyl acetate + 2-propanol and ethyl acetate + 2-propanol at 1.5 MPa were obtained. The data quality was verified by using the point-to-point test of Van Ness and the Fortran routine of Fredenslund et al., which was implemented to third virial coefficient using the method of Orbey and Vera. Experimental data satisfied the validation criterion of Fredenslund et al. The azeotropic point of ethyl acetate + 2-propanol was not found at 1.5 MPa. The ASOG low pressure group contribution models and different versions of UNIFAC were employed for the verification of high pressure vapor–liquid equilibrium data predictions. The ϕ – ϕ approach was applied by using the Peng–Robinson equation of state and employing quadratic mixing rules. The UNIFAC-Lyngby model returned good overall predictions; however the modeling for both systems was best when the Peng–Robinson equation of state was applied.

Vapor pressures of propyl acetate, 1-butanol and 2-butanol and the isobaric (vapor + liquid) equilibrium of n-propyl acetate with 1-butanol at 0.1, 0.15 and 0.6 MPa as well as n-propyl acetate with 2-butanol at 0.15 and 0.6 MPa was investigated using a dynamic stainless steel ebulliometer. The experimental data for the binary systems were tested and verified to be thermodynamically consistent by the point-to-point test of Van Ness. Different thermodynamic–mathematical equations together with several activity coefficient models were used to correlate the experimental data. The average absolute deviations for the vapor phase compositions are all below 0.01. In addition, the ASOG and three versions of UNIFAC group contribution models were used to estimate the (vapor + liquid) equilibrium data. The UNIFAC-Dortmund globally generated the best predictions. The mean error in the activity coefficient was less than 7%. For the n-propyl acetate (1) + 1-butanol (2) system an azeotrope has been verified at 0.15 MPa (x1azexp = y1azexp = 0.949 and Tazexp = 387.61 K) and at 0.6 MPa (x1azexp = y1azexp = 0.783 and Tazexp = 445.68 K) while for the n-propyl acetate (1) + 2-butanol (2) system, the azeotrope at 0.15 MPa was found at x1azexp = y1azexp = 0.331 and Tazexp = 383.03 K and was not detected at 0.6 MPa.

Isobaric vapor–liquid equilibria for the binary system methyl acetate + 2-butanol at 0.3 MPa and 0.6 MPa and ethyl acetate + 2-butanol at 0.3 MPa and 0.6 MPa have been determined. Thermodynamic consistency was checked. The Redlich–Kister and Herington area tests were employed. The Point test, Area test and Infinite dilution test (PAI) of Kojima et al. and the point-to-point test of Van Ness et al. were also applied. The different criteria for validation were considered, and all systems showed an acceptable quality. The results of global and individual deviations on experimental data calculated by using the Fredenslund et al. routine are shown. The different versions of the unique functional group activity coefficient (UNIFAC) and analytical solution of groups (ASOG) predictive group contribution models were applied. The experimental data were also correlated with the Peng–Robinson equation applying quadratic mixing rules.

Isobaric vapor–liquid equilibria for the binary system methyl acetate + 2-propanol at 0.3 and 0.6 MPa and ethyl acetate + 2-propanol at 0.3 and 0.6 MPa have been determined. Thermodynamic consistency was checked applying the Redlich-Kister and Herington area tests. In addition, the PAI test of Kojima et al. and the point-to-point test of Van Ness were applied. Validation criteria were considered for the different tests and all systems showed to be consistent. The global and individual deviations of experimental data were obtained from the Fredenslund routine. Azeotropes in these systems have been determined. It was verified that the singular points move towards lower ester mole fractions with pressure increase. The different versions of the UNIFAC and ASOG predictive group contribution models were applied.

Data from isobaric vapor–liquid equilibrium (VLE) for the binary systems methyl acetate, ethyl acetate, and n-propyl acetate with 1-propanol have been determined at 0.6 MPa employing a metal ebulliometer with recirculation of both phases. The thermodynamic consistency of experimental data has been verified with the Van Ness point-to-point test, using the routine in Fortran proposed by Fredenslund et al. The azeotropic point was observed for the binary systems ethyl acetate/1-propanol and propyl acetate/1-propanol. The activity coefficients of the liquid phase were calculated by considering the nonideality of the vapor phase. The binary systems studied show positive deviation from ideal behavior. Predictions obtained from the group contribution models ASOG and different versions of UNIFAC were verified by comparing the values provided by the models with experimental data of VLE.