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Santiago de Querétaro, Mexico

Miranda-Galindo E.Y.,University of Guanajuato | Segovia-Hernandez J.G.,University of Guanajuato | Hernandez S.,University of Guanajuato | Gutierrez-Antonio C.,CIATEQ | Briones-Ramirez A.,Exxerpro Solutions
Industrial and Engineering Chemistry Research | Year: 2011

Design of reactive distillation sequences is a major computer-aided design challenge. The optimal design of reactive complex distillation systems is a highly nonlinear and multivariable problem, and the objective function used as optimization criterion is generally nonconvex with several local optimums and subject to several constraints. In addition, several attributes for the design of these separation schemes are often conflicting objectives, and the design problem should be represented from a multiple objective perspective. As a result, solving with traditional optimization methods is not reliable because they generally converge to local optimums and often fail to capture the full Pareto optimal front. In this work, we have studied the design of reactive distillation with thermal coupling (using as study case the production of fatty esters), generalizing the use of a multiobjective genetic algorithm with restrictions coupled to Aspen ONE Aspen Plus, previously used in the design and optimization of intensified distillation systems. The results obtained in the Pareto front indicate that the energy consumption of the complex distillation sequence can be reduced significantly by varying operational conditions. Trends in the energy consumption, total annual cost, and greenhouse gas emissions of the thermally coupled reactive distillation sequences can be obtained. © 2010 American Chemical Society. Source

Valera-Medina A.,CIATEQ | Syred N.,University of Cardiff | Kay P.,University of Cardiff | Griffiths A.,University of Cardiff
Experiments in Fluids | Year: 2011

Swirl-stabilised combustion is one of the most widely used techniques for flame stabilisation, uses ranging from gas turbine combustors to pulverised coal-fired power stations. In gas turbines, lean premixed systems are of especial importance, giving the ability to produce low NOx systems coupled with wide stability limits. The common element is the swirl burner, which depends on the generation of an aerodynamically formed central recirculation zone (CRZ) and which serves to recycle heat and active chemical species to the root of the flame as well as providing low-velocity regions where the flame speed can match the local flow velocity. Enhanced mixing in and around the CRZ is another beneficial feature. The structure of the CRZ and hence that of the associated flames, stabilisation and mixing processes have shown to be extremely complex, three-dimensional and time dependent. The characteristics of the CRZ depend very strongly on the level of swirl (swirl number), burner configuration, type of flow expansion, Reynolds number (i.e. flowrate) and equivalence ratio. Although numerical methods have had some success when compared to experimental results, the models still have difficulties at medium to high swirl levels, with complex geometries and varied equivalence ratios. This study thus focuses on experimental results obtained to characterise the CRZ formed under varied combustion conditions with different geometries and some variation of swirl number in a generic swirl burner. CRZ behaviour has similarities to the equivalent isothermal state, but is strongly dependent on equivalence ratio, with interesting effects occurring with a high-velocity fuel injector. Partial premixing and combustion cause more substantive changes to the CRZ than pure diffusive combustion. © Springer-Verlag 2010. Source

Gonzalez-Valadez M.,CIATEQ | Gonzalez-Valadez M.,University of Sheffield | Baltazar A.,CINVESTAV | Dwyer-Joyce R.S.,University of Sheffield
Wear | Year: 2010

This study proposes the use of a simple spring model that relates the interfacial stiffness with the complex reflection coefficient of ultrasound in a rough contact. The spring model cannot be directly related to the real area of contact as this depends on the amount, shape and distribution of contacting asperities. However, it is clear that the model provides a non-destructive tool to easily evaluate both longitudinal and shear interfacial stiffnesses and their ratio. Experimental findings indicate that the interfacial stiffness ratio Kτ/Kσ determined during loading/unloading cycles is sensitive to the roughness level and load hysteresis. The results deviate from the theoretical available micromechanical models, indicating that actual contacting phenomenon is more complex and other variables needed are not accounted for by the models. © 2009 Elsevier B.V. All rights reserved. Source

Hernandez-Hernandez M.,National Autonomous University of Mexico | Camacho-Martinez J.L.,CIATEQ | Gonzalez-Rivera C.,National Autonomous University of Mexico | Ramirez-Argaez M.A.,National Autonomous University of Mexico
Journal of Materials Processing Technology | Year: 2016

A physical model of a batch aluminum degassing reactor equipped with the rotor-injector technique was used to measure deoxidation kinetics of water, assuming that this kinetics is similar to dehydrogenization of aluminum. Performances of three different impeller designs were tested with the model, two of them available commercially, while the third one is a design proposed in this work, which shows a better performance than the two commercial designs reducing the degassing time between 14% and 34%, the gas consumption between 14% and 32%, and an increment in gas efficiency between 22% and 49% compared with the commercial designs. Performance of the impellers in aluminum was tested in a pilot degassing unit, and again, the impeller design proposed showed a better performance by reducing the amount of hydrogen in liquid aluminum after 10 min of degassing 1/2 respect to the commercial design A and 2/3 respect to the design B. © 2016 Elsevier B.V. Source

Gutierrez-Antonio C.,CIATEQ | Briones-Ramirez A.,Exxerpro Solutions | Briones-Ramirez A.,Aguascalientes Institute of Technology
Computer Aided Chemical Engineering | Year: 2010

Evolutionary algorithms have been recognized to be well suited for multiobjective optimization [1]; their principal disadvantage is the large number of evaluations of objective function required [2], which is accentuated when those are computationally expensive. In this work, we propose the use of artificial neuronal networks, ANN, to speed up a multiobjective genetic algorithm with constraints, with base on the work of Gaspar-Cunha [3]. The neuronal network generates an approximated function of the original objective function, which are switched during the optimization; so, we reduce the evaluations of the original objective function and the computational time. The use of approximated functions created by the ANN allows reaching the optimal zone rapidly. Results show a significant reduction in the number of evaluations of the objective function, as well as in computational time, required to reaching the Pareto front. © 2010 Elsevier B.V. Source

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