Instituto Tecnologico Of Aragon Ita

El Puerto de Santa María, Spain

Instituto Tecnologico Of Aragon Ita

El Puerto de Santa María, Spain
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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.


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.


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.


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.


Izquierdo S.,Instituto Tecnologico Of Aragon Ita | Lopez C.I.,Instituto Tecnologico Of Aragon Ita | Valdes J.R.,Instituto Tecnologico Of Aragon Ita | Miana M.,Instituto Tecnologico Of Aragon Ita | And 2 more authors.
Wear | Year: 2012

A methodology is introduced where principal component analysis (PCA) and fractal profile description are combined for characterizing and modelling computational rough surfaces for their use in computer-aided-engineering (CAE) processes. The main idea is to extract principal profiles (PPs) from digital surfaces acquired using confocal microscopy and to model the projection of the original surface onto these PPs by means of Weierstrass-Mandelbrot series; thus, the method is called self-affine principal profile (SAPP) analysis. These PPs are the eigenvectors of the covariance matrix of the digital surface. Profiles modelled in this way preserve information about all scales due to the scale-invariant nature of self-affine profiles. PPs are selected to be those containing the greater amount of information about the surface in terms of spatial variance. It is shown that just the first few PPs are enough to approximately reproduce a given surface and that this approximation can be measured. The methodology is applied to build families of surfaces with specific fractal dimensions and to characterize surface evolution due to wear. The quality of surfaces obtained is quantified in terms of mesh resolution, number of PPs used for modelling the surface and number of terms in the Weierstrass-Mandelbrot series, which are all relevant parameters for building meshes for CAE. © 2011 Elsevier B.V.


Martinez F.J.,Instituto Tecnologico Of Aragon Ita | Canales M.,Instituto Tecnologico Of Aragon Ita | Bielsa J.M.,Instituto Tecnologico Of Aragon Ita | Jimenez M.A.,Instituto Tecnologico Of Aragon Ita
Wear | Year: 2010

The present paper reports the process for obtaining a law of wear by friction that reproduces the behaviour of a contact pair between a guide shoe insert, made of TPU, and the corresponding guide, made of steel, in a lift guide shoe application. After an initial identification of the TPU wear type as fatigue wear, the wear law is fitted from tests carried out in a tribometer, obtaining a relationship between the TPU worn volume and two fundamental variables: the travelled distance and the applied load. Archard's law, a relationship commonly used by many authors in the literature, is taken as a starting point, analysing its validity in this case and proposing an improved fitting by means of a potential law.Additionally, in order to analyse in depth the physical phenomena that guide the wear process present in the contact pair under study, and corroborating what was stated by the law fitted previously, the wear process is studied by means of observations by SEM and confocal microscopy by finite element simulations at micro-level, analysing the interaction between material and countermaterial. The results from these analyses are compared with conclusions stated by several authors in the literature in similar studies of other polymers. Finally, this study is completed with an analysis of the analogy between wear and mechanical fatigue, relating both phenomena, in order to confirm the assertion stated in previous studies: the wear process in TPU occurs as a result of repeated crack propagation in the subsurface layer of the material at small scale. © 2009 Elsevier B.V. All rights reserved.


Bielsa J.M.,Instituto Tecnologico Of Aragon Ita | Canales M.,Instituto Tecnologico Of Aragon Ita | Martinez F.J.,Instituto Tecnologico Of Aragon Ita | Jimenez M.A.,Instituto Tecnologico Of Aragon Ita
Tribology International | Year: 2010

This paper presents a finite element based methodology for obtaining pressure dependent friction laws from experimental tribometer tests on rubber-metal contacts. Tribometer tests are simulated for analyzing the area of contact and obtaining an approximation to the contact pressure distribution in the test. The proposed methodology will be applied to the evaluation of experimental results from tribometer tests run in flat on flat and flat on cylinder configurations, for which flat and cylindrical countermaterials have been produced with very similar surface morphologies and, therefore, theoretically the same pressure-dependent friction law. © 2009 Elsevier Ltd. 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 | Alcala N.,Instituto Tecnologico Of Aragon Ita | Canales M.,Instituto Tecnologico Of Aragon Ita | Jimenez M.A.,Instituto Tecnologico Of Aragon Ita
Meccanica | Year: 2014

The present paper reports the methodology used to numerically implement thermal effects in long stroke tribometer (LST) wear tests. Thermal effects correspond to the heating produced by friction between the parts in tests. Those tests consist in the sliding, in reciprocating configuration, of samples of thermoplastic polyurethane, over a fixed steel countermaterial. The numerical implementation of the LST tests is carried out by means of fully coupled thermal-stress finite element simulations, using different theories of convection and conduction for setting up parameters in polymer–steel contact pairs. This methodology is applied to the numerical analysis of different load and test reference temperature conditions, setting up a validation with experimental tests under some specific conditions. This work is only focused on the numerical implementation of thermal effects. As further step to this work, this methodology will be applied to the development and numerical implementation of a polymer–steel wear model with thermal effects, characterised from wear tribometer test results. © 2014, Springer Science+Business Media Dordrecht.


Bernad C.,Instituto Tecnologico Of Aragon Ita | Laspalas A.,Instituto Tecnologico Of Aragon Ita | Gonzalez D.,Instituto Tecnologico Of Aragon Ita | Liarte E.,Instituto Tecnologico Of Aragon Ita | Jimenez M.A.,Instituto Tecnologico Of Aragon Ita
Packaging Technology and Science | Year: 2010

Laboratory simulation of transport vibration has been the object of many studies in recent years due to the financial implications of potential customer claims in respect of damage caused during product distribution and the need for tools for packaging optimization. Most of these works concentrate on the special nature of transport vibrations and how to reproduce them: Power Spectral Density (PSD) profiles related to road and truck characteristics, the non-stationary aspects of the environment, the non-Gaussian characteristics of the recorded vibrations and the best procedures for meaningful laboratory testing. In the present work, a different point of view is applied to the issue. The paper deals with the dynamics of different corrugated stacked packaging units by means of operational modal analysis and a 6 degrees of freedom multi-axis shaker table. The results show the already known non-linear behaviour of the paperboard containers and the natural frequencies and modes likely to appear in the packaging. The relevance of bending-like modes in relation to laboratory testing is discussed. © 2010 John Wiley & Sons, Ltd.

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