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Bayod-Rujula A.A.,University of Zaragoza | Lorente-Lafuente A.M.,Instituto Tecnologico Of Aragon Ita | Cirez-Oto F.,University of Zaragoza
Energy | Year: 2011

The use of two axes tracking systems has been widely implemented because of the higher rates in energy production that these systems can achieve. However, the reduction of the PV modules cost makes the economic advantage of these tracking systems not so evident and this has aroused the interest of analysing them from other points of view such as efficiency or energy performance and environmental impact.Most of the existing LCA studies related to Photovoltaic systems are focused in the comparison of the different technologies used for cell production; some reports include also the module assembly, but there is little information regarding the environmental impact caused by the complete solar photovoltaic plant.In this paper, a Life cycle analysis of two types of installations (with and without solar tracking) in different geographic locations is presented. The methodology, based on recognized international standards, provides the best framework for assessing the most relevant factors causing the environmental impacts and gives relevant information for further improvements. The results also allow the comparison of different solutions and the calculation of the Energy and Environmental Payback time of both configurations. © 2011 Elsevier Ltd.

Novaresio V.,Polytechnic University of Turin | Garcia-Camprubi M.,University of Zaragoza | Izquierdo S.,Polytechnic University of Turin | Izquierdo S.,Instituto Tecnologico Of Aragon Ita | And 2 more authors.
Computer Physics Communications | Year: 2012

The generation of direct current electricity using solid oxide fuel cells (SOFCs) involves several interplaying transport phenomena. Their simulation is crucial for the design and optimization of reliable and competitive equipment, and for the eventual market deployment of this technology. An open-source library for the computational modeling of mass-transport phenomena in SOFCs is presented in this article. It includes several multicomponent mass-transport models (i.e. Fickian, Stefan-Maxwell and Dusty Gas Model), which can be applied both within porous media and in porosity-free domains, and several diffusivity models for gases. The library has been developed for its use with OpenFOAM ®, a widespread open-source code for fluid and continuum mechanics. The library can be used to model any fluid flow configuration involving multicomponent transport phenomena and it is validated in this paper against the analytical solution of one-dimensional test cases. In addition, it is applied for the simulation of a real SOFC and further validated using experimental data. © 2011 Elsevier B.V. All rights reserved.

Bergamasco L.,Instituto Tecnologico Of Aragon Ita | Izquierdo S.,Instituto Tecnologico Of Aragon Ita | Ammar A.,Arts et Metiers ParisTech
Journal of Non-Newtonian Fluid Mechanics | Year: 2013

Micro-macro imulations of polymeric solutions rely on the coupling between macroscopic conservation equations for the fluid flow and stochastic differential equations for kinetic viscoelastic models at the microscopic scale. In the present work we introduce a novel micro-macro numerical approach, where the macroscopic equations are solved by a finite-volume method and the microscopic equation by a lattice-Boltzmann one. The kinetic model is given by molecular analogy with a finitely extensible non-linear elastic (FENE) dumbbell and is deterministically solved through an equivalent Fokker-Planck equation. The key features of the proposed approach are: (i) a proper scaling and coupling between the micro lattice-Boltzmann solution and the macro finite-volume one; (ii) a fast microscopic solver thanks to an implementation for Graphic Processing Unit (GPU) and the local adaptivity of the lattice-Boltzmann mesh; (iii) an operator-splitting algorithm for the convection of the macroscopic viscoelastic stresses instead of the whole probability density of the dumbbell configuration. This latter feature allows the application of the proposed method to non-homogeneous flow conditions with low memory-storage requirements. The model optimization is achieved through an extensive analysis of the lattice-Boltzmann solution, which finally provides control on the numerical error and on the computational time. The resulting micro-macro model is validated against the benchmark problem of a viscoelastic flow past a confined cylinder and the results obtained confirm the validity of the approach. © 2013 Elsevier B.V.

Martinez F.J.,Instituto Tecnologico Of Aragon Ita | Jimenez M.A.,Instituto Tecnologico Of Aragon Ita | Martinez M.A.,Aragon Institute of Engineering Research
Meccanica | Year: 2014

The aim of this work is to study the applicability of a numerical-experimental methodology for wear modelling to the design of a lift car installation by means of finite element simulations. The study focuses on the sliding of guide shoe inserts, made of thermoplastic polyurethane, TPU, over fixed lift car guides, made of steel. This component includes the same polymer-metal contact pair formerly studied in a tribometer test, working under sliding conditions in reciprocating relative movement. This simulation allows to get final wear predictions in the component considering real installation parameters, as well as the wear distribution in the contact faces of the guide shoe inserts with the counterpart. Additionally, the work also includes a numerical sensitivity analysis of how several design variables determine the wear amount of the component. © 2013 Springer Science+Business Media Dordrecht.

Martinez F.J.,Instituto Tecnologico Of Aragon Ita | Canales M.,Instituto Tecnologico Of Aragon Ita | Izquierdo S.,Instituto Tecnologico Of Aragon Ita | Jimenez M.A.,Instituto Tecnologico Of Aragon Ita | Martinez M.A.,Aragon Institute of Engineering Research
Wear | Year: 2012

The objective of this work is to present an integral methodology to numerically model the wear phenomena by friction in a polymer-metal contact pair, showing the development of a numerical tool to implement a wear model in the commercial finite element code Abaqus. The contact pair in which this work is based corresponds to the contact between a guide shoe insert for an elevator, made of thermoplastic polyurethane elastomers (TPU), and the corresponding guide, made of steel. Tribometer tests are planned to fit the numerically implemented wear model as well as to validate it. These tests are briefly described as an introduction to the numerical fitting of the data from which the wear model is obtained. The numerical tool in which the wear model in a polymer-steel contact pair is implemented is based on a methodology that combines the use of the user subroutine Umeshmotion, which offers the possibility of implementing a wear model in any general form, several routines to result access, and the adaptive meshing technique, a mesh smoothing tool available in Abaqus based on ALE (Augmented Lagrangian Eulerian) methods. With this technique, it is possible to eliminate material during the simulation as well as to maintain a high-quality mesh throughout an analysis by allowing the mesh to move independently of the material. As the tests that are carried out in the tribometer to fit and to validate the wear model require long travel distances and a large number of cycles, a real simulation of those tests would require a huge calculation time. Therefore, to simulate the wear process equivalent to the travelled distances in the tests in an affordable simulation time, an accelerated numerical procedure of the wear process is also proposed in this work. To numerically implement the wear model, and as it is usually stated in polymers, it is previously necessary to set up a procedure for determining the relationship between the friction coefficient and the contact pressure for the material and countermaterial contact pair. Finally, a validation of the methodology with a new wear tribometer test under different conditions to those stated to characterise the model is also presented. © 2012 Elsevier B.V. All rights reserved.

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