The Experts below are selected from a list of 7092 Experts worldwide ranked by ideXlab platform

Maria Del Mar Olaya - One of the best experts on this subject based on the ideXlab platform.

Ali Haghtalab - One of the best experts on this subject based on the ideXlab platform.

  • osmotic coefficient data and an excess Gibbs Energy Function for single phase complex system of glucose alcohol water
    Fluid Phase Equilibria, 2009
    Co-Authors: Samaneh Sanjari, Mohsen Nosrati, Ali Haghtalab
    Abstract:

    Abstract Thermodynamics of single-phase complex systems of glucose + alcohol + water is significantly important in food and pharmaceutical industries. The water activity is a practical parameter in thermodynamic characterization in food and pharmaceutical and other biological industries, which its value has an important role in growing microorganisms and rate of reactions. In this work, the NRTL-NRF excess Gibbs Function has extended for ternary system of water, different alcohols (as second molecular solvent) and a special molecular solute like a sugar. The extended NRTL-NRF model with three parameters was used for correlation of the osmotic coefficient of the aqueous systems of glucose and alcohol at different concentrations. The data of the osmotic coefficient of water for these systems are obtained by an isopiestic method. The adjustable parameters are calculated by optimization of the experimental data of the osmotic coefficient using the Nedler–Mead algorithm. It is shown that the results of the modified NRTL-NRF model demonstrate low deviation from the experimental data.

  • a nonelectrolyte local composition model and its application in the correlation of the mean activity coefficient of aqueous electrolyte solutions
    Fluid Phase Equilibria, 2009
    Co-Authors: Ali Haghtalab, Seyed Hossein Mazloumi
    Abstract:

    Abstract The local composition models have been widely used for the correlation of activity coefficient of nonelectrolyte and electrolyte solutions. A new equation for the excess Gibbs Energy Function is developed based on the local composition expression of Wilson and the random reference state. This new Function, the nonelectrolyte Wilson nonrandom factor (N-Wilson-NRF) model, is presented in the form of a molecular framework so that it can be used for both nonelectrolyte and electrolyte solutions. Without any particular assumptions for ionic solutions, the new Function is used to described the short-range contribution of the excess Gibbs Energy of electrolyte solutions. The long-range contribution is represented by Pitzer–Debye–Huckel model. With two adjustable parameters per electrolyte, the new model is applied to correlate the mean activity coefficients of more than 150 binary aqueous electrolyte solutions at 25 °C. The results are compared with various local composition models such as the electrolyte-NRTL, electrolyte NRF-Wilson and electrolyte-NRTL-NRF models. The comparison of the results with experiment demonstrates that the new model can correlate the experimental data accurately. Moreover, the model shows high precision of predictability for the osmotic coefficient of binary electrolyte solutions.

J A Reyes - One of the best experts on this subject based on the ideXlab platform.

Laureano Jimenez - One of the best experts on this subject based on the ideXlab platform.

  • the parametrization problem in the modeling of the thermodynamic behavior of solutions an approach based on information theory fundamentals
    Industrial & Engineering Chemistry Research, 2019
    Co-Authors: Adriel Sosa, Luis Fernandez, J Ortega, Laureano Jimenez
    Abstract:

    This work shows a new approach to the parameter-fitting problem useful in the solutions thermodynamic field, providing a more objective framework to obtain better empirical/semiempirical models for chemical engineering applications. A model based on the excess Gibbs Energy Function gE is used to represent the behavior of real solutions, together with its first derivative hE, using a combined modeling under the paradigm of multiobjective optimization. The problem is formulated as an MINLP methodology to simultaneously consider two aspects: the model complexity and the best parametrization to prevent the overfitting, controlling the trade-off between them by applying the Akaike Information Criterion to gE residuals. Two different solvers, one deterministic (SBB/CONOPT) and another evolutionary (GA), are used, and their ability to solve the problem is analyzed. The designed methodology is applied to three highlighted VLE cases in chemical engineering, and the results obtained show the ability of the method t...

Lijun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Thermal Vacancy on Thermodynamic Behaviors in BCC W Close to Melting Point: A Thermodynamic Study
    Materials, 2018
    Co-Authors: Ying Tang, Lijun Zhang
    Abstract:

    As temperature increases, the thermal vacancy concentration in pure metals dramatically increases and causes some strongly non-linear thermodynamic behaviors in pure metals when close to their melting points. In this paper, we chose body-centered cubic (bcc) W as the target and presented a thermodynamic model to account for its Gibbs Energy of pure bcc W from 0 K to melting point by including the contribution of thermal vacancy. A new formula for interaction part was proposed for describing the quadratic temperature behavior of vacancy formation Energy. Based on the experimental/first-principles computed thermodynamic properties, all the parameters in the Gibbs Energy Function were assessed by following the proposed two-step optimization strategy. The thermodynamic behaviors, i.e., the strong nonlinear increase for temperature dependence of heat capacities at high temperatures and a nonlinear Arrhenius plot of vacancy concentration, in bcc W can be well reproduced by the obtained Gibbs Energy. The successful description of thermal vacancy on such strongly non-linear thermodynamic behaviors in bcc W indicates that the presently proposed thermodynamic model and optimization strategy should be universal ones and are applicable to all other metals.