Bulk elastic fingering instability in Hele-Shaw cells

We demonstrate experimentally the existence of a purely elastic fingering instability which arises when air penetrates into an elastomer confined in a Hele-Shaw cell. Fingers appear sequentially and propagate within the bulk of the material as soon as a critical strain, independent of the elastic modulus, is exceeded. Their width depends non-linearly on the distance between the confining glass plates. A key element in the driving force of the instability is the adhesion of layers of gels to the plates, which results in a considerable expense of elastic energy during the growth of the air bubble.Comment: Submitted to Physical Review letters; 5 pages; 6 figure

REGSOLexpert: Entrainer Selection Tool for waste solvent recovery by batch distillation processes

A general procedure to systematize the search of several alternatives enabling the separation of non-ideal binary mixtures such as pressure-swing distillation, azeotropic and extractive distillation is presented. The use of heterogeneous entrainers is specially highlighted

General methodology for exergy balance in ProSimPlus® process simulator

This paper presents a general methodology for exergy balance in chemical and thermal processes integrated in ProSimPlus® as a well-adopted process simulator for energy efficiency analysis. In this work, as well as using the general expressions for heat and work streams, all of exergy balance is presented within only one software in order to fully automate exergy analysis. In addition, after exergy balance, the essential elements such as source of irreversibility for exergy analysis are presented to help the user for modifications on either process or utility system. The applicability of the proposed methodology in ProSimPlus® is shown through a simple scheme of Natural Gas Liquids (NGL) recovery process and its steam utility system. The methodology does not only provide the user with necessary exergetic criteria to pinpoint the source of exergy losses, it also helps the user to find the way to reduce the exergy losses. These features of the proposed exergy calculator make it preferable for its implementation in ProSimPlus® to define the most realistic and profitable retrofit projects on the existing chemical and thermal plants

HIx system thermodynamic model for hydrogen production by the sulfur-iodine cycle

The HIx ternary system (H2O – HI – I2) is the latent source of hydrogen for the Sulfur – Iodine thermo-chemical cycle. After analysis of the literature data and models, a homogeneous approach with the Peng-Robinson equation of state used for both the vapor and liquid phase fugacity calculations is proposed for the first time to describe the phase equilibrium of this system. The MHV2 mixing rule is used, with UNIQUAC activity coefficient model combined with of hydrogen iodide solvation by water. This approach is theoretically consistent for HIx separation processes operating above HI critical temperature. Model estimation is done on selected literature vapor – liquid, liquid – liquid, vapor – liquid – liquid and solid – liquid equilibrium data for the ternary system and the three binaries subsystems. Validation is done on the remaining literature data. Results agree well with the published data, but more experimental effort is needed to improve modeling of the HIx system

Bunsen section thermodynamic model for hydrogen production by the sulfur-Iodine cycle

A model for the Bunsen section of the Sulfur – Iodine thermo-chemical cycle is proposed, where sulfur dioxide reacts with excess water and iodine to produce two demixing liquid aqueous phases (H2SO4 rich and HI rich) in equilibrium. Considering the mild temperature and pressure conditions, the UNIQUAC activity coefficient model combined with Engels’ solvation model is used. The complete model is discussed, with HI solvation by water and by iodine as well as H2SO4 solvation by water, leading to a very high complexity with almost hundred parameters to be estimated from experimental data. Taking into account the water excess, a successful reduced model with only 15 parameters is proposed after defining new apparent species. Acids total dissociation and total H+ solvation by water are the main assumptions. Results show a good agreement with published experimental data between 25 °C and 120 °C

Modeling of mixed-solvent electrolyte systems

International audienceModels for mixed-solvent strong electrolytes, using an equation of state (EoS) are reviewed in this work. Through the example of ePPC-SAFT (that includes a Born term and ionic association), the meaning and the effect of each contribution to the solvation energy and the mean ionic activity coefficient are investigated. The importance of the dielectric constant is critically reviewed, with a focus on the use of a salt-concentration dependent function. The parameterization is performed using two adjustable parameters for each ion: a minimum approach distance () and an association energy (). These two parameters are optimized by fitting experimental activity coefficient and liquid density data, for all alkali halide salts simultaneously, in the range 298K to 423K. The model is subsequently tested on a large number of available experimental data, including salting out of Methane/Ethane/CO 2 /H 2 S. In all cases the deviations in bubble pressures were below 20% AADP. Predictions of vapor-liquid equilibrium of mixed solvent electrolyte systems containing methanol, ethanol are also made where deviations in bubble pressures were found to be below 10% (AADP)

Recherche de tiers corps pour la distillation azéotropique discontinue

La distillation batch est une technique de séparation importante dans l’industrie chimique, notamment pour les mélanges azéotropiques. Une procédure d’exploration systématique de la faisabilité de procédés de distillation batch, pouvant nécessiter l’ajout d’un tiers corps a été élaborée au sein du logiciel RegSolExpert®. L’illustration consiste à séparer le mélange eau – acétonitrile formant un azéotrope à température de bulle minimal

Vapor-liquid equilibria measurements of bitter orange aroma compounds highly diluted in boiling hydro-alcoholic solutions at 101.3 kPa

In this work, experimental vapor−liquid equilibria (VLE) of water + ethanol + five aroma compound (two monoterpene hydrocarbons, α-pinene and D-limonene, and three oxygenated compounds, linalool, citral, and linalool oxide) mixtures were measured at boiling point at 101.3 kPa for ethanol molar fractions ranging from 0.0140 to 0.8389. The five aroma compounds were selected for their strong contribution to the aroma of the distillate of bitter orange essential oil. First, the thermodynamic consistency of the experimental VLE data was validated. Then the NRTL and Henry's law type models were tested to correlate the experimental data. Good agreement was obtained with both models to predict the phase equilibrium of the oxygenated compounds, and a better agreement was obtained with Henry's law type models for the monoterpene hydrocarbons in this kind of mixture