Mass effect on the soret coefficient in n-alkane mixtures

We have determined the Soret coefficient of different equimolar and non equimolar n-alkane mixtures from measurements of the molecular diffusion and thermal diffusion coefficients. It is shown that equimolar mixtures behave as isotopic-like mixtures in which only the mass effect contributes to the Soret effect. In non equimolar mixtures, a small linear dependence with the molar fraction is observed. Finally, we have obtained a new correlation, which allows the determination of the Soret coefficient of n-alkane mixtures using the data of viscosity, the thermal expansion coefficient of the pure components, and the density of the equimolar mixture

Sorption isotherm, glass transition, and diffusion coefficient of polyacrylamide/water solutions

The sorption isotherm, the glass transition, and the mutual diffusion coefficient of polyacrylamide/water solutions are obtained experimentally. All of these parameters are measured in the concentrated regime by gravimetric experiments. The mutual diffusion coefficient is also measured at high solvent concentrations by the sliding symmetric tubes technique. Three different polyacrylamide batches differing in their molar mass have been characterized. The results are expressed in terms of simple empirical correlations, suitable for use in process modelization or numerical simulations

Determination of molecular diffusion coefficient in n-Alkane binary mixtures: empirical correlations

In this work we have measured the molecular diffusion coefficient of the n-alkane binary series nCi-nC6, nCi-nC10, and nCi-nC12 at 298 K and 1 atm and a mass fraction of 0.5 by using the so-called sliding symmetric tubes technique. The results show that the diffusion coefficient at this concentration is proportional to the inverse viscosity of the mixture. In addition, we have also measured the diffusion coefficient of the systems nC12-nC6, nC12-nC7, and nC12-nC8 as a function of concentration. From the data obtained, it is shown that the diffusion coefficient of the n-alkane binary mixtures at any concentration can be calculated from the molecular weight of the components and the dynamic viscosity of the corresponding mixture at 50% mass fraction

CFD Analysis of can Heating Process

In this work, the thermal sterilization process in food cans has been analyzed using Computational Fluid Dynamics (CFD). STAR CCM+ software has been used in order to develop a numerical model to study the heating process of standard and the recently proposed toroidal shaped cans. The model has been validated comparing the results with the ones obtained experimentally and numerically that can be found in the literature. A good agreement between the obtained numerical results and the experimental ones has been obtained. The results also agree with other numerical models previously developed in the literature. Once the model has been validated, taking advance of the possibility to easily introduce movement in the simulations, new variables have been analyzed in the system using this model, such as rotational movement of the can. The model developed has been used to study the efficiency of the sterilization process with the two types of cans by means of calculating the temperature inside the systems and calculating the F0 parameter. It can be seen that the efficiency of the sterilization process is better in the toroidal cans. It has been also checked that CFD models can be very helpful in analyzing the temperature profiles inside the cans and making sure that the correct temperature has been obtained inside the can and the sterilization process has been correctly carried out

Thermodiffusion, molecular diffusion and Soret coefficient of binary and ternary mixtures of n-hexane, n-dodecane and toluene

n this study, the thermodiffusion, molecular diffusion, and Soret coefficients of 12 binary mixtures composed of toluene, n-hexane and n-dodecane in the whole range of concentrations at atmospheric pressure and temperatures of 298.15 K and 308.15 K have been determined. The experimental measurements have been carried out using the Thermogravitational Column, the Sliding Symmetric Tubes and the Thermal Diffusion Forced Rayleigh Scattering techniques. The results obtained using the different techniques show a maximum deviation of 9% for the thermodiffusion coefficient, 8% for the molecular diffusion coefficient and 2% for the Soret coefficient. For the first time we report a decrease of the thermodiffusion coefficient with increasing ratio of the thermal expansion coefficient and viscosity for a binary mixture of an organic ring compound with a short n-alkane. This observation is discussed in terms of interactions between the different components. Additionally, the thermogravitational technique has been used to measure the thermodiffusion coefficients of four ternary mixtures consisting of toluene, n-hexane and n-dodecane at 298.15 K. In order to complete the study, the values obtained for the molecular diffusion coefficient in binary mixtures, and the thermodiffusion coefficient of binary and ternary mixtures have been compared with recently derived correlations

CFD Analysis of Can Heating Process

In this work, the thermal sterilization process in food cans has been analyzed using Computational Fluid Dynamics (CFD). STAR CCM+ software has been used in order to develop a numerical model to study the heating process of standard and the recently proposed toroidal shaped cans. The model has been validated comparing the results with the ones obtained experimentally and numerically that can be found in the literature. A good agreement between the obtained numerical results and the experimental ones has been obtained. The results also agree with other numerical models previously developed in the literature. Once the model has been validated, taking advance of the possibility to easily introduce movement in the simulations, new variables have been analyzed in the system using this model, such as rotational movement of the can. The model developed has been used to study the efficiency of the sterilization process with the two types of cans by means of calculating the temperature inside the systems and calculating the F0 parameter. It can be seen that the efficiency of the sterilization process is better in the toroidal cans. It has been also checked that CFD models can be very helpful in analyzing the temperature profiles inside the cans and making sure that the correct temperature has been obtained inside the can and the sterilization process has been correctly carried out.publishedVersio

Benchmark values for the Soret, thermodiffusion and molecular diffusion coefficients of the ternary mixture tetralin+isobutylbenzene+n-dodecane with 0.8-0.1-0.1 mass fraction

Abstract: With the aim of providing reliable benchmark values, we have measured the Soret, thermodiffusion and molecular diffusion coefficients for the ternary mixture formed by 1,2,3,4-tetrahydronaphthalene, isobutylbenzene and n-dodecane for a mass fraction of 0.8-0.1-0.1 and at a temperature of 25°C. The experimental techniques used by the six participating laboratories are Optical Digital Interferometry, Taylor Dispersion technique, Open Ended Capillary, Optical Beam Deflection, Thermogravitational technique and Sliding Symmetric Tubes technique in ground conditions and Selectable Optical Diagnostic Instrument (SODI) in microgravity conditions. The measurements obtained in the SODI installation have been analyzed independently by four laboratories. Benchmark values are proposed for the thermodiffusion and Soret coefficients and for the eigenvalues of the diffusion matrix in ground conditions, and for Soret coefficients in microgravity conditions. Graphical abstract: [Figure not available: see fulltext.].SCOPUS: ar.jinfo:eu-repo/semantics/publishe