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1 to 50 of 182 results
  • Environmental assessment of small-scale production of wood chips as a fuel for residential heating boilers

     Esteban Dalmau, Bernat; Riba Ruiz, Jordi Roger; Baquero Armans, Grau; Puig Vidal, Rita; Rius Carrasco, Antoni
    Renewable energy
    Date of publication: 2014-02
    Journal article

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    This work performs a comparative life cycle assessment (LCA) of two fuels for heating boilers, namely wood chips and oil. The LCA methodology allows comparing the environmental impacts of the two analyzed fuels, thus assessing which is environmentally more advantageous. The study is focused on Mediterranean forests located in the Argençola region (Catalonia, northeastern Spain) by applying forest management practices focused to ensure a sustainable exploitation. The direct use of wood chips as a fuel for boilers simplifies notably the number of processes involved in producing such a fuel. The results presented clearly show the environmental benefits of using small-scale produced wood chips instead of fossil oil by analyzing representative impact categories defined by the CML and EDIP methods, even when considering the changes in the carbon stock in the forests under analysis due to the management approach adopted. A sensitivity analysis has also been conducted to assess the impact of the data with higher uncertainty on the final LCA results.

  • Detection of interturn faults in PMSMs with different winding configuration

     Saavedra Ordoñez, Harold; Urresty Betancourt, Julio; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    Energy conversion and management
    Date of publication: 2014-03-03
    Journal article

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  • Redesign process of a 765 kV AC substation connector by means of 3D-FEM simulations

     Hernandez Guiteras, Joan; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    Simulation modelling practice and theory
    Date of publication: 2014-03-03
    Journal article

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  • Runout tracking in electric motors using self-mixing interferometry

     Atashkhooei, Reza; Urresty Betancourt, Julio; Royo Royo, Santiago; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    IEEE-ASME transactions on mechatronics
    Date of publication: 2014-01-17
    Journal article

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  • Contributions on corona onset voltage calculation for EHV and UHV substation connectors

     Hernandez Guiteras, Joan
    Defense's date: 2014-03-28
    Universitat Politècnica de Catalunya
    Theses

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    Les investigacions realitzades en aquesta tesi es va realitzar en el marc d'un acord empresa - universitat . L'objectiu d'aquesta investigació és determinar la tensió d'inici de l'efecte corona en geometries no uniformes per evitar la seva aparició, i així poder incidir en la fase de disseny del connectors de subestació de EHV i UHV i equipmanet auxiliar de línia instal·lats en condicions de funcionament, d'acord amb les normes internacionals . Per tant , s'ha prestat una consideració especial a l'estudi i el modelatge de l'efecte corona per assegurar que els connectors dissenyats es trobin gairebé lliures d'aquest efecte indesitjable . Degut a de la natura d'aquest acord marc, la investigació científica s'ha vist delimitada a l'aplicabilitat en un entorn industrial a fi d'obtenir la accreditació, segons les normatives internacionals, dels productes analitzats.Per tant , els temes tractats en aquesta investigació inclouen l'anàlisi de camps electromagnètics i els càlculs de l'efecte corona , sent aquest últim de gran importància en el disseny dels connectors de subestació per EHV i UHV . És objectiu d'aquesta tesi proporcionar augmentar el coneixement i aportar mètodes matemàtics apropiats per avaluar el comportament dielèctric de connectors de subestació per a sistemes de transmissió de EHV i UHV . En concret , s'ha destinat un capítol a la introducció a l'estat de la tècnica en connectors de la subestació i l'efecte corona, seguit d'un capítol adreçat a l'estudi dels camps elèctrics i magnètics creats pels connectors de la subestació i les equacions empíriques per al càlcul de l'effecte corona. A continuació, s'introdueix una descripció macroscòpica del corona a través de la descripció matemàtica del procés de ionització, tant des del cas estacionari com el transitori. Seguit de la descripció microscòpica a través de funcions de distribució estadístiques utilitzdes per descriure i calcular els paràmetres d'ionització del corona en l'aire . Finalment, es troba el capítol de tancament amb les principals aportacions de la investigació realitzada.

  • Shaft Trajectory Analysis in a Partially Demagnetized Permanent-Magnet Synchronous Motor

     Urresty Betancourt, Julio César; Atashkhooei, Reza; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis; Royo Royo, Santiago
    IEEE transactions on industrial electronics
    Date of publication: 2013-08
    Journal article

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    Demagnetization faults have a negative impact on the behavior of permanent-magnet synchronous machines, thus reducing their efficiency, generating torque ripple, mechanical vibrations, and acoustic noise, among others. In this paper, the displacement of the shaft trajectory induced by demagnetization faults is studied. It is proved that such faults may increase considerably the amplitude of the rotor displacement. The direct measure of the shaft trajectory is performed by means of a noncontact self-mixing interferometric sensor. In addition, the new harmonics in the back electromotive force (EMF) and the stator current spectrum arising from the shaft displacement are analyzed by means of finite-element method (FEM) simulations and experimental tests. Since conventional finite-element electromagnetic models are unable to predict the harmonics arising from the shaft trajectory displacement, an improved finite-element model which takes into account the measured trajectory has been developed...

  • A Cumulative Energy Demand indicator (CED), life cycle based, for industrial waste management decision making

     Puig Vidal, Rita; Fullana Palmer, Pere; Baquero Armans, Grau; Riba Ruiz, Jordi Roger; Bala Gala, Alba
    Waste management
    Date of publication: 2013-12
    Journal article

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    Life cycle thinking is a good approach to be used for environmental decision-support, although the complexity of the Life Cycle Assessment (LCA) studies sometimes prevents their wide use. The purpose of this paper is to show how LCA methodology can be simplified to be more useful for certain applications. In order to improve waste management in Catalonia (Spain), a Cumulative Energy Demand indicator (LCA-based) has been used to obtain four mathematical models to help the government in the decision of preventing or allowing a specific waste from going out of the borders. The conceptual equations and all the subsequent developments and assumptions made to obtain the simplified models are presented. One of the four models is discussed in detail, presenting the final simplified equation to be subsequently used by the government in decision making. The resulting model has been found to be scientifically robust, simple to implement and, above all, fulfilling its purpose: the limitation of waste transport out of Catalonia unless the waste recovery operations are significantly better and justify this transport.

  • Influence of the stator windings configuration in the currents and zero-sequence voltage harmonics in permanent magnet synchronous motors with demagnetization faults

     Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    IEEE transactions on magnetics
    Date of publication: 2013-08
    Journal article

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    Demagnetization faults in permanent magnet synchronous motors may generate specific fault harmonic frequencies in the stator currents and the zero-sequence voltage component (ZSVC) spectra. Hence, by analyzing the stator currents or/and the ZSVC spectra it is possible to develop fault diagnosis schemes to detect such faults. In order to have a broad view of such effects, a representative set of stator windings configurations must be considered. By analyzing different stator windings configurations this paper shows that the amplitude of the harmonic frequencies of both the stator currents and the ZSVC spectrato be analyzed are significantly influenced by the stator windings configuration. It is also proved that depending on the winding configuration, new harmonic components may emerge in both spectra. The results presented in this paper may help to develop fault diagnosis schemes based on the acquisition and further analysis of the stator currents and the ZSVC harmonic components.

  • Magnet shape influence on the performance of AFPMM in a torus configuration

     Saavedra Ordoñez, Harold; Riba Ruiz, Jordi Roger; Hernandez Guiteras, Joan; Romeral Martinez, Jose Luis
    International Conference on Power Engineering, Energy and Electrical Drives
    Presentation's date: 2013-05-16
    Presentation of work at congresses

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  • Redesign of a spherical corona shield for UHV substation connectors

     Hernandez Guiteras, Joan; Riba Ruiz, Jordi Roger; Saavedra Ordoñez, Harold
    International Conference on Power Engineering, Energy and Electrical Drives
    Presentation's date: 2013-05-15
    Presentation of work at congresses

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  • Inter-turn fault detection in five-phase PMSMs. Effects of the fault severity

     Saavedra Ordoñez, Harold; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics and Drives
    Presentation's date: 2013-08-30
    Presentation of work at congresses

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    This paper deals with the effects of inter-turn short circuit faults in five-phase permanent magnet synchronous motors (PMSMs). For this purpose a finiteelements model (FEM) of a faulty machine with 1, 2 and 4 inter-turns in short circuit is analyzed. From the results of this model the effects of these fault severities in the stator currents and zero-sequence voltage components (ZSVC) harmonics is analyzed and the possibility of developing a fault diagnosis scheme based on the changes in their spectral content is exposed. Moreover, the effect of the fault severity on the total power losses in the machine is presented. Inter-turn faults generate large circulating currents which may lead to catastrophic failures. Therefore it is very important to know the increase in power losses in the machine due to the occurrence of such faults for applying corrective actions at the precise time once the fault has been diagnosed.

  • Magnet shape influence on the performance of AFPMM with demagnetization

     Saavedra Ordoñez, Harold; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    Annual Conference of the IEEE Industrial Electronics Society
    Presentation's date: 2013-11-13
    Presentation of work at congresses

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  • Diagnosis of interturn faults in pmsms operating under nonstationary conditions by applying order tracking filtering

     Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    IEEE transactions on power electronics
    Date of publication: 2013
    Journal article

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    Interturn faults in permanent magnet synchronous machines may have very harmful effects if not early identified. This study deals with the detection of such faults when the machine operates under varying speed conditions. The performance of two methods is analyzed and compared, i.e., the analysis of the third harmonic of the stator currents and the first one of the zero- sequence voltage components. The Vold¿Kalman filtering order tracking algorithm is introduced and applied to track the harmonics of interest when the machine operates under a wide speed range and different load levels. This study also presents two reliable fault indicators especially focused to detect stator winding interturn faults under nonstationary speed conditions. Experimental results endorse the methodology proposed, showing its potential to carry out a reliable fault diagnosis scheme

  • Shaft trajectory analysis in a partially demagnetized permanent magnet synchronous motor

     Urresty Betancourt, Julio; Atashkhooei, Reza; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis; Royo Royo, Santiago
    IEEE transactions on industrial electronics
    Date of publication: 2013-08-01
    Journal article

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  • Feasibility analysis of reduced-scale air breakdown tests in high voltage laboratories combined with the use of scaled test cages

     Hernandez Guiteras, Joan; Riba Ruiz, Jordi Roger; Casals Torrens, Pau; Bosch Tous, Ricardo
    IEEE Transactions on dielectrics and electrical insulation
    Date of publication: 2013-10
    Journal article

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    Breakdown and corona extra-and ultra-high voltage tests are expensive, timeconsuming and require large and extremely costly high-voltage halls, of which there are very few worldwide. Some of these limiting requirements may be minimized by using test cages and by applying reduced-scale tests. In this work the feasibility of performing breakdown reduced-scale tests combined with the use of test cages is analyzed. For this purpose a three-dimensional finite elements based methodology is introduced to determine the geometric dimensions of the test cage in order to adjust the test voltage according to the allowable output voltage of a conventional high-voltage laboratory. To validate the findings of this work, breakdown tests of a full-scale 500 kVRMS substation connector and a 1:3 reduced-scale model using test cages are conducted in a highvoltage laboratory, which maximum allowable output voltage is of 125 kVRMS. Results from this work show that by using appropriately designed test cages and scaled versions of the test samples the results may be scaled with high accuracy.

  • A back-emf based method to detect magnet failures in PMSMs

     Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    IEEE transactions on magnetics
    Date of publication: 2013
    Journal article

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    Demagnetization faults are troublesome because they have a profound impact on the overall performance of permanent magnet synchronous motors (PMSMs). This work presents and veri¿es experimentally a system to detect such faults which is based on the measure of the zero sequence voltage component (ZSVC). The proposed method is also appropriate for inverter fed machines and is particularly useful when dealing with fault tolerant systems. A fault severity index which allows quantifying the harshness of such faults is also proposed and its behavior is analyzed from experimental data. Features of the proposed method include low computational burden, simplicity and high sensitivity. Experimental results conducted at different speed and load conditions show the potential of the proposed fault severity index for online diagnosis of demagnetization failures

  • Determination of the corona inception voltage in an extra high voltage substation connector

     Hernandez Guiteras, Joan; Riba Ruiz, Jordi Roger; Casals Torrens, Pau
    IEEE Transactions on dielectrics and electrical insulation
    Date of publication: 2013-02
    Journal article

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    Environmental life cycle assessment of rapeseed straight vegetable oil as self-supply agricultural biofuel  Open access

     Baquero Armans, Grau; Esteban Dalmau, Bernat; Puig Vidal, Rita; Riba Ruiz, Jordi Roger; Rius Carrasco, Antoni
    Renewable energy
    Date of publication: 2013-02-01
    Journal article

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    Biofuels are nowadays considered a questionable environmental alternative to fossil fuels. In that context, this work analyses the environmental impacts when introducing rapeseed on the traditional and current wheat and barley agricultural rotation by means of a comparative life cycle assessment (LCA). The introduction of rapeseed, the correctness of its conversion to obtain straight vegetable oil and its use as self-consumption biofuel in tractors are evaluated. Life cycle assessment is used in this work to evaluate the impacts of different considered scenarios. A sensitivity analysis has also been conducted. The results presented show a modest environmental improvement (diminishment of 6 out of the 10 analyzed environmental impacts) when introducing rapeseed to local crop rotations and its partial conversion to oil to be used as fuel in existing diesel engines. Additionally, the ratio between the energy obtained and the total energy input shows moderate positive results when comparing the latter case with the current one. Results from this study can be used to support research and decision making to assess the convenience of introducing alternative fuels in agricultural exploitations

  • An Energy Management Strategy for Plug-in Hybrid Electric Vehicles

     Bader, Benjamin
    Defense's date: 2013-11-29
    Department of Electronic Engineering, Universitat Politècnica de Catalunya
    Theses

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  • Salinity effect on the corona onset for a 765 kV AC substation connector

     Hernandez Guiteras, Joan; Riba Ruiz, Jordi Roger; Sanllehi, Josep; Bosch Tous, Ricardo
    International Council on Large Electric Systems
    Presentation's date: 2012-08-29
    Presentation of work at congresses

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    Outdoor substations placed in coastal areas are affected by saline environments. In the technical literature it is found extensive information regarding insulations problems in presence of saline environments [1]. The accumulation of salts and other contaminants promotes the onset of partial discharges on the devices subjected to very high voltages. Insulators are also affected by this phenomenon. While rainfall has a cleaning effect on the insulator surface, humidity enhances the corrosion effect and degrades the performance of insulation [2], favouring onset conditions for partial discharge. Corrosion due to saline environments or dirt increases the roughness of the insulator surface, thus facilitating the appearance of partial discharges [3]. It is well known that the air pollution has a great impact on metals corrosion. Chloride ions are common in coastal environments, because seawater acts as a source of air mineralization. Deposition of chloride ions on metal surfaces intensifies metallic corrosion, thus degrading the conductor surface [4]. In this work the behaviour of a 765 kVRMS AC (line-to-line voltage) outdoor substation connector is analyzed when operating under both dry conditions and under wet saline environments by means of three-dimensional finite elements simulations (3D-FEM). FEM simulations show that the electric field strength in the connector surroundings does not exceed the electric breakdown strength for air under clean and dry atmospheric conditions when energized at its rated voltage, 765 kVRMS AC (line-to-line). These results are corroborated by means of experimental measurements carried out in a high-voltage laboratory. Both, the laboratory tests and the 3D-FEM simulations performed in this study concluded that the corona onset voltage is approximately 980 kVRMS AC (line-to-line voltage). Additionally, 3D-FEM simulations allow detecting the connector weakest points regarding to electrical stress. Hence, this software allows redesigning the connector geometry to optimize its performance, thus minimizing the corona occurrence risk and their associated unwanted effects. Additionally, FEM simulations performed under a saline atmosphere were carried out by including a thin conductive saline moisture layer acting as a wetting film on the connector surface. Results revealed that saline environments worsen the connector behaviour, thus favouring corona onset conditions and their related effects.Outdoor substations placed in coastal areas are affected by saline environments. In the technical literature it is found extensive information regarding insulations problems in presence of saline environments [1]. The accumulation of salts and other contaminants promotes the onset of partial discharges on the devices subjected to very high voltages. Insulators are also affected by this phenomenon. While rainfall has a cleaning effect on the insulator surface, humidity enhances the corrosion effect and degrades the performance of insulation [2], favouring onset conditions for partial discharge. Corrosion due to saline environments or dirt increases the roughness of the insulator surface, thus facilitating the appearance of partial discharges [3]. It is well known that the air pollution has a great impact on metals corrosion. Chloride ions are common in coastal environments, because seawater acts as a source of air mineralization. Deposition of chloride ions on metal surfaces intensifies metallic corrosion, thus degrading the conductor surface [4]. In this work the behaviour of a 765 kVRMS AC (line-to-line voltage) outdoor substation connector is analyzed when operating under both dry conditions and under wet saline environments by means of three-dimensional finite elements simulations (3D-FEM). FEM simulations show that the electric field strength in the connector surroundings does not exceed the electric breakdown strength for air under clean and dry atmospheric conditions when energized at its rated voltage, 765 kVRMS AC (line-to-line). These results are corroborated by means of experimental measurements carried out in a high-voltage laboratory. Both, the laboratory tests and the 3D-FEM simulations performed in this study concluded that the corona onset voltage is approximately 980 kVRMS AC (line-to-line voltage). Additionally, 3D-FEM simulations allow detecting the connector weakest points regarding to electrical stress. Hence, this software allows redesigning the connector geometry to optimize its performance, thus minimizing the corona occurrence risk and their associated unwanted effects. Additionally, FEM simulations performed under a saline atmosphere were carried out by including a thin conductive saline moisture layer acting as a wetting film on the connector surface. Results revealed that saline environments worsen the connector behaviour, thus favouring corona onset conditions and their related effects.

  • Comparative life cycle analysis between traditional and organic farming local rotations to produce straight vegetable oil used as self-supply biofuel in agriculture

     Baquero Armans, Grau; Esteban Dalmau, Bernat; Rius Carrasco, Antoni; Puig Vidal, Rita; Riba Ruiz, Jordi Roger
    European Biomass Conference and Exhibition
    Presentation's date: 2012-06-18
    Presentation of work at congresses

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  • Analysis of demagnetization faults in surface-mounted permanent magnet synchronous with inter-turns and phase-to-ground short-circuits

     Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis; Saavedra Ordoñez, Harold
    International Conference on Electrical Machines
    Presentation's date: 2012-09-03
    Presentation of work at congresses

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    Demagnetization faults are troublesome in permanent magnet synchronous motors since they may greatly reduce their performance and efficiency. Additionally, the temperature of the magnets deeply influences the remanent flux density. Hence, the temperature may have a demagnetization effect on the magnets. This work studies the behavior of a surface-mounted permanent magnet synchronous motor running under inter-turn and phase-to-ground short-circuits faults. Concretely, the temperature increase of such faults and a potential reversible or irreversible demagnetization of the rotor magnets are analyzed. The analysis is based on 2D FEM simulations which includes rotor magnet skew. The simulations conducted in this work clearly show that inter-turn faults do not lead to irreversible demagnetization. However, in case of a phase-to-ground short-circuit an irreversible demagnetization may take place instantaneously

  • Economic assessment of forest chips versus heating oil in domestic boilers in the mediterranean region

     Esteban Dalmau, Bernat; Baquero Armans, Grau; Riba Ruiz, Jordi Roger; Puig Vidal, Rita; Rius Carrasco, Antoni
    European Biomass Conference and Exhibition
    Presentation's date: 2012-06-18
    Presentation of work at congresses

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  • Study of rapeseed oil degradation in different storage conditions

     Esteban Dalmau, Bernat; Baquero Armans, Grau; Rius Carrasco, Antoni; Puig Vidal, Rita; Riba Ruiz, Jordi Roger
    European Biomass Conference and Exhibition
    Presentation's date: 2012-06-21
    Presentation of work at congresses

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    Identificación de muestras de papel mediante espectrometria IR y métodos multivariables  Open access

     Riba Ruiz, Jordi Roger
    Afinidad: revista de química teórica y aplicada
    Date of publication: 2012-04-01
    Journal article

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    Actualmente en todo el mundo se consume una gran cantidad de papel reciclado. Ello ha provocado la fabricación de papel que contiene muchos tipos de impurezas, por lo que las empresas papeleras se están viendo con la necesidad de desarrollar métodos para controlar la calidad del papel entrante para así garantizar su calidad. Para ello en este trabajo se investiga un método muy rápido y no destructivo para identificar diferentes tipos de papel que permita desechar el papel entrante que no cumpla con unos requisitos mínimos de calidad. De este modo se puede mejorar el comportamiento de la máquina de papel y al mismo tiempo asegurar la calidad del producto final. Ello se hace en base al estudio de los espectros FTIR (espectroscopia del infrarrojo medio por transformada de Fourier) y NIR (espectroscopia del infrarrojo cercano) tratados mediante ICA (análisis de componentes independientes) como técnica multivariable de extracción de características para reducir la cantidad de variables utilizadas y k-NN (k vecinos más cercanos) como técnica de clasificación. Los resultados experimentales muestran que es posible identificar con éxito más de un 90% de las muestras estudiadas, de una forma rápida, muy automatizada y de forma no destructiva.

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    Comparative Study of Multivariate Methods to Identify Paper Finishes Using Infrared Spectroscopy  Open access

     Riba Ruiz, Jordi Roger; Canals Parelló, Trini; Cantero Gómez, Maria Rosa
    IEEE transactions on instrumentation and measurement
    Date of publication: 2012-03-09
    Journal article

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    Recycled paper is extensively used worldwide. In the last decades its market has expanded considerably. The increasing use of recycled paper in papermaking has led to the production of paper containing several types of impurities. Consequently, wastepaper mills are forced to implement quality control schemes for evaluating the incoming wastepaper stock, thus guarantying the specifications of the final product. The main objective of this work is to present a fast and reliable system for identifying different paper types. Therefore, undesirable paper types can be refused, improving the performance of the paper machine and the final quality of the paper manufactured. For this purpose two fast techniques, i.e., Fourier transform mid-infrared (FTIR) and reflectance near-infrared (*IR) were applied to acquire the infrared spectra of the paper samples. *ext, four processing multivariate methods, i.e., principal component analysis (PCA), canonical variate analysis (CVA), extended canonical variate analysis (ECVA) and support vector machines (SVM) were employed in the feature extraction –or dimension reduction– stage. Afterwards, the k nearest neighbors algorithm (k**) was used in the classification phase. Experimental results show the usefulness of the proposed methodology and the potential of both FTIR and *IR spectroscopic methods. Using the FTIR spectrum in association with SVM and k** the system achieved maximum classification accuracy of 100%, whereas using the *IR spectrum in association with ECVA or SVM and k** the system achieved maximum classification accuracy of 96.4%

  • Detection of demagnetization faults in surface-mounted permanent magnet synchronous motors by means of the zero-sequence voltage component

     Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Delgado Prieto, Miquel; Romeral Martinez, Jose Luis
    IEEE transactions on energy conversion
    Date of publication: 2012-03-01
    Journal article

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    This paper develops and analyzes an online methodology to detect demagnetization faults in surface-mounted permanent magnet synchronous motors. The proposed methodology, which takes into account the effect of the inverter that feeds the machine, is based on monitoring the zero-sequence voltage component of the stator phase voltages. The theoretical basis of the proposed method has been established. Attributes of the method presented here include simplicity, very low computational burden, and high sensibility. Since the proposed method requires access to the neutral point of the stator windings, it is especially useful when dealing with fault tolerant systems. A simple expression of the zero-sequence voltage component is deduced, which is proposed as a fault indicator parameter. Both simulation and experimental results presented in this paper show the potential of the proposed method to provide helpful and reliable data to carry out an online diagnosis of demagnetization failures in the rotor permanent magnets.

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    Temperature dependence of density and viscosity of vegetable oils  Open access

     Esteban Dalmau, Bernat; Riba Ruiz, Jordi Roger; Baquero Armans, Grau; Rius Carrasco, Antoni; Puig Vidal, Rita
    Biomass and bioenergy
    Date of publication: 2012-07
    Journal article

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    The straight use of vegetable oils as fuel in diesel engines entails adjusting several physical properties such as density and viscosity. By adequately heating the vegetable oil before entering the injection system, its physical parameters can reach values very close to that of diesel fuel. Consequently, by properly adjusting the temperature of vegetable oils used as fuel, it is possible to improve their combustion performance, thus avoiding premature engine aging due to incomplete burning. In this study the density and viscosity of several vegetable oils are studied within a wide variety of temperatures. The optimal range of temperatures at which each vegetable oil should operate in order to adjust its properties to those of automotive diesel and biodiesel is then found. Additionally an empirical relationship between the dependence of viscosity with density is presented. Thus, by means of the above-described relationship, through measuring the density of a given oil, its viscosity can be directly deduced

  • Electrical and Magnetic Faults Diagnosis in Permanent Magnet Synchronous Motors  Open access

     Urresty Betancourt, Julio César
    Defense's date: 2012-09-21
    Department of Electronic Engineering, Universitat Politècnica de Catalunya
    Theses

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    Permanent magnet synchronous motors (PMSMs) are an alternative in critical applications where high-speed operation, compactness and high efficiency are required. In these applications it is highly desired to dispose of an on-line, reliable and cost-effective fault diagnosis method. Fault prediction and diagnosis allows increasing electric machines performance and raising their lifespan, thus reducing maintenance costs, while ensuring optimum reliability, safe operation and timely maintenance. Consequently this thesis is dedicated to the diagnosis of magnetic and electrical faults in PMSMs. As a first step, the behavior of a healthy machine is studied, and with this aim a new 2D finite element method (FEM) modelbased system for analyzing surface-mounted PSMSs with skewed rotor magnets is proposed. It is based on generating a geometric equivalent non-skewed permanent magnet distribution which accounts for the skewed distribution of the practical rotor, thus avoiding 3D geometries and greatly reducing the computational burden of the problem. To diagnose demagnetization faults, this thesis proposes an on-line methodology based on monitoring the zero-sequence voltage component (ZSVC). Attributes of the proposed method include simplicity, very low computational burden and high sensibility when compared with the well known stator currents analysis method. A simple expression of the ZSVC is deduced, which can be used as a fault indicator parameter. Furthermore, mechanical effects arising from demagnetization faults are studied. These effects are analyzed by means of FEM simulations and experimental tests based on direct measurements of the shaft trajectory through self-mixing interferometry. For that purpose two perpendicular laser diodes are used to measure displacements in both X and Y axes. Laser measurements proved that demagnetization faults may induce a quantifiable deviation of the rotor trajectory. In the case of electrical faults, this thesis studies the effects of resistive unbalance and stator winding inter-turn short-circuits in PMSMs and compares two methods for detecting and discriminating both faults. These methods are based on monitoring and analyzing the third harmonic component of the stator currents and the first harmonic of the ZSVC. Finally, the Vold-Kalman filtering order tracking algorithm is introduced and applied to extract selected harmonics related to magnetic and electrical faults when the machine operates under variable speed and different load levels. Furthermore, different fault indicators are proposed and their behavior is validated by means of experimental data. Both simulation and experimental results show the potential of the proposed methods to provide helpful and reliable data to carry out a simultaneous diagnosis of resistive unbalance and stator winding inter-turn faults.

  • Characterization of the surface tension of vegetable oils to be used as fuel in diesel engines

     Esteban Dalmau, Bernat; Riba Ruiz, Jordi Roger; Baquero Armans, Grau; Puig Vidal, Rita; Rius, Antonio
    Fuel (Guildford)
    Date of publication: 2012-12
    Journal article

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    Straight vegetable oils may be used as fuel in existing diesel engines. However, some precautions should be taken into account because some of their physicochemical properties must be adjusted through tem- perature control to ensure enhanced combustion, thus avoiding premature aging of the engine. Although it is well known that surface tension plays a prevalent role in the fuel atomization process which affects the combustion quality, there is lack of published information about its variation with temperature when dealing with straight vegetable oils to be used as fuel in unmodified diesel engines. In this work, the surface tension of several vegetable oils is studied in a wide temperature interval. The optimal range of temperatures at which each vegetable oil should operate to adjust its properties to those of automotive diesel and biodiesel is found. Moreover, an empirical relationship between the dependence between surface tension and density is presented

  • Application of the zero-sequence voltage component to detect stator winding inter-turn faults in PMSMs

     Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Romeral Martinez, Jose Luis
    Electric power systems research
    Date of publication: 2012-08
    Journal article

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    This paper develops and analyzes a methodology for detecting stator winding inter-turn faults in surface-mounted permanent magnet synchronous motors. The proposed methodology is based on monitoring the zero-sequence voltage component having into account the effects of the inverter that usually feeds the machine. The theoretical basis of such a method is established from the parametric model of the machine. Attributes of the method presented here include simplicity, high accuracy, low computational burden and high sensibility. Additionally, it is especially useful when dealing with fault tolerant systems. From this model the expression of the zero sequence voltage component is deduced, which is used to detect stator winding inter-turn faults. Both simulation and experimental results presented in this work show the potential of the proposed method to provide helpful and reliable data to carry out an online diagnosis of such faults.

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    Evaluation of machine learning techniques for electro-mechanical system diagnosis  Open access

     Delgado Prieto, Miquel; Garcia Espinosa, Antonio; Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Ortega Redondo, Juan Antonio
    European Conference on Power Electronics and Applications
    Presentation's date: 2011-09-01
    Presentation of work at congresses

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    The application of intelligent algorithms, in electro-mechanical diagnosis systems, is increasing in order to reach high Reliability and performance ratios in critical and complex scenarios. In this context, different multidimensional intelligent diagnosis systems, based on different machine learning techniques, are presented and evaluated in an electro-mechanical actuator diagnosis scheme. The used diagnosis methodology includes the acquisition of different physical magnitudes from the system, such as machine vibrations and stator currents, to enhance the monitoring capabilities. The features calculation process is based on statistical time and frequency domains features, as well as timefrequency fault indicators. A features reduction stage is, additionally, included to compress the descriptive fault information in a reduced feature set. After, different classification algorithms such as Support Vector Machines, Neural Network, k-Nearest Neighbors and Classification Trees are implemented. Classification ratios over inputs corresponding to previously learnt classes, and generalization capabilities with inputs corresponding to learnt classes slightly modified are evaluated in an experimental test bench to analyze the suitability of each algorithm for this kind of application.

    Postprint (author’s final draft)

  • LCA of forest chips versus diesel boilers in the Mediterranean region

     Esteban Dalmau, Bernat; Baquero Armans, Grau; Puig Vidal, Rita; Riba Ruiz, Jordi Roger; Rius Carrasco, Antoni
    European Biomass Conference and Exhibition
    Presentation's date: 2011-06-09
    Presentation of work at congresses

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    ABSTRACT: Obtaining energy from forest chips is a technology widely used in many regions. There are currently many studies and applications on the use of forest biomass [1,2], mainly promoted by policies aimed to reduce greenhouse gases. The forests of the Mediterranean area are characterized by a mountain relief. This orography makes difficult the selective biomass extraction from the forest. Thus, the biomass is accumulated in the forest and becomes a serious danger for wildfires. Forest fires are considered the most important natural impact in the Mediterranean region due to its effect to ecosystems, as some authors state [3,4]. This study aims to compare by means of LCA methodology the use of forest chips and diesel fuels in a boiler, focusing on the difficulty of extracting the wood from a Mediterranean forest area. In the Mediterranean area there are no environmental studies centred on the extraction of timber from forest areas without affecting the life in the forest. This work presents an LCA, where the difficulties of extracting the biomass from the forest and its use in heating boilers are presented.

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    Detection of inter-turns short circuits in permanent magnet synchronous motors operating under transient conditions by means of the zero sequence voltage  Open access

     Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Saavedra Ordoñez, Harold; Romeral Martinez, Jose Luis
    European Conference on Power Electronics and Applications
    Presentation's date: 2011-09-01
    Presentation of work at congresses

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    This work proposes the zero sequence voltage component (ZSVC) of the stator three-phase voltages as a method for detecting winding inter-turns short circuits in permanent magnet synchronous motors PMSM operating under transient conditions. Additionally it proves the linear relationship between the ZSVC and speed, which is effectively used as a fault severity index. The acquired ZSVC temporal signal is processed by means of the Hilbert-Huang transform (HHT). Experimental results presented in this work show the advantages of the method to provide helpful data for online diagnosis of stator winding inter-turn faults.

    Postprint (author’s final draft)

  • Sustainability assessment of straight vegetable oil used as self-supply biofuel in agriculture

     Baquero Armans, Grau; Esteban Dalmau, Bernat; Puig Vidal, Rita; Riba Ruiz, Jordi Roger; Rius Carrasco, Antoni
    European Biomass Conference and Exhibition
    Presentation's date: 2011-06-09
    Presentation of work at congresses

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    This work proposes and analyses a model for an agricultural fuel self-supply exploitation. The model is based on the current extended crop rotation of wheat and barley in Anoia region (Catalonia, Spain). The introduction of rapeseed to the current crop rotation and its conversion into oil to be used as agricultural fuel is presented. Life cycle assessment methodology is used to carry out an environmental and an economic assessment. Environmental results show a preference for the vegetable oil based scenario in terms of CO2 equivalent emissions and energy consumption as well as no major difference in land used for the considered scenarios. Economic assessment shows a preference for the rapeseed introduction in the current crop rotation agricultural system without converting the seed into oil and using it as biofuel. The basis to develop the life cycle social assessment is also presented, calculating a social impact category as an example.

  • Analysis of demagnetization faults in surface-mounted permanent magnet synchronous motors with symmetric windings

     Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Saavedra Ordoñez, Harold; Romeral Martinez, Jose Luis
    IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics and Drives
    Presentation's date: 2011-09-07
    Presentation of work at congresses

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    This paper analyzes a surface-mounted permanent magnet synchronous motor with symmetric winding configuration running under demagnetization fault. The analysis is based on 2D FEM simulations which includes rotor magnet skewed effects. Two types of demagnetization are analyzed; uniform and local demagnetization. It is proposed the use of zero-sequence voltage component for fault diagnosis purposes. Simulations and experimental results show the suitability of the method.

  • Feature extraction of demagnetization faults in permanent-magnet synchronous motors based on box-counting fractal dimension

     Delgado Prieto, Miquel; Garcia Espinosa, Antonio; Riba Ruiz, Jordi Roger; Urresty Betancourt, Julio César; Ortega Redondo, Juan Antonio
    IEEE transactions on industrial electronics
    Date of publication: 2011-05
    Journal article

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    This paper presents a methodology for feature extraction of a new fault indicator focused on detecting demagnetization faults in a surface-mounted permanent-magnet synchronous motors operating under nonstationary conditions. Preprocessing of transient-current signals is performed by applying Choi–Williams distribution to highlight the salient features of this demagnetization fault. In this paper, fractal dimension calculation based on the computation of the box-counting method is performed to extract the optimal features for diagnosis purposes. It must be noted that the applied feature-extraction process is autotuned, so it does not depend on the severity of the fault and is applicable to a wide range of operating conditions of the motor. The performance of the proposed system is validated experimentally. According to the obtained results, the proposed methodology is reliable and feasible for diagnosing demagnetization faults in industrial applications.

  • Modeling of surface-mounted permanent magnet synchronous motors with stator winding inter-turn faults

     Romeral Martinez, Jose Luis; Urresty Betancourt, Julio César; Riba Ruiz, Jordi Roger; Garcia Espinosa, Antonio
    IEEE transactions on industrial electronics
    Date of publication: 2011-05-29
    Journal article

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    This paper develops and analyzes a parametric model for simulating healthy and faulty surface-mounted permanent magnet synchronous motors. It allows studying the effects of stator winding interturn short-circuit faults. A relevant feature of the developed model is that it deals with spatial harmonics due to a nonsinusoidal rotor permanent magnet configuration. Additionally, the proposed model is valid for studying the behavior of these machines running under nonstationary conditions, including load or speed variations. Stator current spectra obtained from simulations performed by applying the proposed model show a close similitude with experimental results, highlighting the potential of such a model to understand the effects of stator winding failures on the current spectrum and allowing it to carry out an automatic diagnosis of such faults.

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    An eddy-current-based sensor for preventing knots in metallic wire drawing processes  Open access

     Esteban Dalmau, Bernat; Riba Ruiz, Jordi Roger; Baquero Armans, Grau
    Nondestructive testing and evaluation
    Date of publication: 2011-04-07
    Journal article

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    During metallic wire drawing processes, the presence of knots and the failure to detect them can lead to long production interruptions, significant economic losses and a lower quality of final product. Consequently, there is a pressing need to develop methods for real-time detection and prevention of this fault. In this paper, a sensor to prevent the formation of knots during the metallic wire drawing process is presented and evaluated by means of experimental data. This fast, inexpensive, non-contact sensor is based on electromagnetic principles such as eddy current induction, magnetic reluctance variations and magnetic coupling. The proposed sensor without direct contact can detect knots in a target metallic wire by measuring the impedance variations of a calibrated sensing coil caused by either a knot or an unwound loop rising from a wire rod. The incorporation of this type of sensor into a wire-drawing machine can avoid the tightening of the knot, thereby reducing downtime and increasing the security and reliability of the process. Experiments were conducted using a scale model of the above proposed system. This allowed highlighting the sensor’s potential by carrying out an automatic, real-time knot detection during steel wire drawing

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    An evaluation of the life cycle cost of rapeseed oil as a straight vegetable oil fuel to replace petroleum diesel in agriculture  Open access

     Baquero Armans, Grau; Esteban Dalmau, Bernat; Riba Ruiz, Jordi Roger; Rius Carrasco, Antoni; Puig Vidal, Rita
    Biomass and bioenergy
    Date of publication: 2011-08
    Journal article

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    The use of straight vegetable oil (SVO) as biofuel has been recognized as a valid substitute of diesel fuel in the agricultural sector under specific circumstances. Its direct use reduces most of the chemical processes involved when converting it into biodiesel, thus lowering harmful emissions. This study presents the economic analysis of a self-supply farming model that uses rapeseed as its fuel base. This model addresses agricultural environmental concerns and can even minimize dependence on the fluctuating costs of diesel fuel. The use of SVO in agriculture can help reduce farmers’ vulnerability to fossil fuel prices. The economic evaluation of the model proposed in this study shows clear economic benefits of introducing rapeseed to the traditional crop rotation of wheat and barley. The key factors analyzed in this model are diesel fuel price, diesel fuel grants and crop aids. The current situation in Spain favors the use of diesel fuel in agriculture rather than rapeseed SVO due to an 8% profit difference. However, results show that changes in key factors slightly affect the profit margin, calculating a difference of only 3.7% for particular factor combinations. Combined environmental-friendly agriculture supporting policies are necessary to cover this slight profit difference to promote this biofuel

  • From life cycle assessment to life cycle management: A case study on industrial waste management policy making

     Fullana Palmer, Pere; Puig Vidal, Rita; Bala, Alba; Baquero Armans, Grau; Riba Ruiz, Jordi Roger; Raugei, Marco
    Journal of industrial ecology
    Date of publication: 2011-06
    Journal article

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  • Is it environmentally advantageous to use vegetable oil directly as biofuel instead of converting it to biodiesel?

     Esteban Dalmau, Bernat; Baquero Armans, Grau; Puig Vidal, Rita; Riba Ruiz, Jordi Roger; Rius Carrasco, Antoni
    Biomass and bioenergy
    Date of publication: 2011-03
    Journal article

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    Use of Rapeseed Straight Vegetable Oil as Fuel Produced in Small-Scale Exploitations  Open access

     Baquero Armans, Grau; Esteban Dalmau, Bernat; Riba Ruiz, Jordi Roger; Puig Vidal, Rita; Rius Carrasco, Antoni
    Date of publication: 2011-08-01
    Book chapter

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    This chapter presents a method to produce rapeseed and process it to obtain rapeseed oil and rapeseed cake meal from a small-scale point of view. It also shows how rapeseed oil can be used as fuel in diesel engines for agriculture self-consumption. A production, processing and use-as-fuel model for rapeseed oil is also presented, analysing environmentally and economically the use of rapeseed oil as fuel compared to other agricultural production alternatives. The results are evaluated for dry Mediterranean area conditions

  • Ús de l'oli vegetal cru com a biocarburant per autoconsum agrícola: avaluacio de la sostenibilitat del sistema a Catalunya  Open access

     Baquero Armans, Grau
    Defense's date: 2011-07-06
    Department of Mechanical Engineering, Universitat Politècnica de Catalunya
    Theses

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    La introducció de la colza en la rotació de conreus i la producció i ús d’oli vegetal cru (OVC) com a biocarburant per autoconsum agrícola presenten alguns avantatges respecte al sistema tradicional de conreu de la Catalunya central, com una major productivitat i la capacitat d’autoabastament de combustible. El principal objectiu d’aquesta tesi és estudiar la viabilitat ambiental i econòmica de l’autoconsum d’oli vegetal cru en una explotació agrícola. També es planteja l’avaluació social mitjançant la metodologia de l’anàlisi de cicle de vida. A partir de les dades recopilades es defineix un model agrícola parametritzat, essent el camp el principal element i tenint en compte els fluxos d’entrada i sortida del mateix i dels processos que el complementen. Aquest model permet avaluar diferents escenaris de producció, que inclouen la rotació tradicional (blat, ordi i guaret), la rotació actual (blat i ordi) i la rotació proposada (colza, blat i ordi). Addicionalment el model també té en compte el processat de la llavor i l’ús de dièsel o oli vegetal com a carburants en la maquinària agrícola. Cal remarcar que el model proposat no pretén produir OVC com a substitut del dièsel per al transport, sinó que brinda la possibilitat de produir el combustible que es consumeix en una explotació usant una part de les terres conreades. En el context d’aquest model es realitza un estudi del processat mecànic de la colza per l’obtenció d’oli vegetal i un estudi sobre la seva adequació per ser usat com a carburant. Primer s’analitza l’índex d’acidesa en funció de la temperatura de premsat per determinar el punt òptim de treball. Seguidament, a partir del contingut en fòsfor s’estudien els processos de post-tractament de l’oli obtingut (filtrat i desgomat). L’anàlisi de cicle de vida (ACV) és la metodologia emprada per avaluar el model en les tres branques de la sostenibilitat (ambiental, econòmica i social). Aquesta metodologia permet estudiar processos productius de manera exhaustiva i avaluar-los de forma quantitativa. Es duu a terme una ACV ambiental seguint la metodologia ja desenvolupada i es realitza una ACV econòmica a partir de la guia vigent, tot i no existir normativa específica com en el cas de l’ACV ambiental. La metodologia de l’ACV social encara es troba en els seus inicis i per tant, tot i que es detalla com s’ha de realitzar, l’ACV social del model proposat no es pot completar. L’avaluació ambiental del model mostra certa preferència per l’ús de l’OVC en front al dièsel, tot i que encara queda camí per optimitzar i ajustar els motors tèrmics on s’ha d’utilitzar l’OVC per ajustar-ne les emissions. El rendiment de la fase de premsat i l’origen de l’electricitat consumida també són punts que tenen una gran influència en els resultats. Aquests factors són clau per obtenir en el futur una reducció important dels impactes ambientals. A partir de l’avaluació econòmica es detecta un clar interès econòmic per introduir la colza en la rotació de conreus actual. Per altra banda, el processat de la colza i l’ús de l’OVC representen econòmicament una petita disminució en el benefici (8,0%). Aquesta diferència queda reduïda a menys de la meitat si el dièsel agrícola no es subvenciona i es tenen en compte les emissions de CO2 segons el mercat del carboni. Aquestes improbables mesures polítiques poden afavorir un major rendiment econòmic del model proposat. Per altra banda, el model proporciona una menor dependència en front a les variacions del preu de mercat del dièsel. Finalment, en el context de desenvolupament actual de la metodologia d’avaluació social, es defineixen nous indicadors i es planteja el càlcul d’una categoria d’impacte social a partir del càlcul dels seus corresponents indicadors. Per a futurs estudis seria interessant disposar d’una metodologia d’ACV social ben desenvolupada per poder avaluar el model proposat enfront a l’actual, ja que és en la part social on s’intueixen les majors diferències entre els dos sistemes estudiats.

    The introduction of rapeseed in the crop rotation and the production and use of straight vegetable oil (SVO) as self- supply biofuel in agricultural machinery have some advantages over the traditional cultivation system of Catalonia central region. These advantages can be summarized in a greater productivity and the capacity to supply its own farm fuel. The main objective of this PhD is to study the environmental and economic feasibility of the SVO self-supply in a farm. This work also handles the social assessment using the life cycle analysis methodology. A parameterized agricultural model is defined according the collected data. The model takes into account the input and output flows of the field, as long as the other processes of the proposed farm model. This model allows the evaluation of different production scenarios, including the traditional crop rotation (wheat, barley and fallow), the current crop rotation (wheat and barley) and the proposed crop rotation (rapeseed, wheat and barley). Additionally, the model takes into consideration the processing and use of diesel or SVO as fuel in the agricultural machinery. Note that the proposed model is not intended to produce OVC to be a diesel substitute for transport. On the other hand, it provides the chance to produce fuel for its consumption in the field work using a portion of the cultivated land. In the model framework, a study of the mechanical processing of rapeseed into oil and a study of its suitability for its use as fuel are carried out. First the acidity index is analyzed to determine the optimal working point regarding the pressing temperature. After that, the phosphorus content is analysed to evaluate the oil refining treatments (filtering and degumming). Life cycle assessment (LCA) methodology is used to evaluate the model in the three pillars of sustainability (environmental, economic and social). This method allows the production processes evaluation and their quantitative assessment. An environmental LCA is carried out using the already developed methodology and the current regulations. The economic LCA is done according to the published guidelines, as there is no specific regulation developed. The social LCA methodology is still in its early stages and therefore, even giving the details on how to perform it, the social evaluation of the proposed model can not be completed. The environmental assessment of the model shows a slight preference for SVO in front of diesel. However, the results can be improved by a better optimization and adjustment of diesel engines to use SVO, which can lower their emissions. The pressing yield and the electrical mix are processes that have also a high influence on the results. These key factors can lead to a significant reduction of environmental impacts in the future. From the economic evaluation, a clear economic interest to introduce rapeseed in the current crop rotation is revealed. Conversely, the processing of rapeseed and the use of SVO leads to an small profit decrease (8,0%). This difference is reduced by more than a half if agricultural diesel was not subsidized and if the CO2 emissions were accounted according to the carbon market. These unlikely policy measures may promote the economic viability of the proposed model. Even though, the use of self-supplied SVO in farming can help to reduce the dependency on fuel price flux, giving independence to the farmer. Finally, in the current development context of the social assessment methodology, new indicators are defined and the calculation of a social impact category based on the calculation of its corresponding indicators is presented. The major differences between the two systems studied are expected to be found in their social assessment. Thus, further well-developed social LCA methodology will be necessary to evaluate the proposed model against the current system.

    La introducción de la colza en la rotación de cultivos y la producción y uso de aceite vegetal crudo como biocarburante para autoconsumo agrícola presentan ciertas ventajas respecto al sistema tradicional de cultivo de la Cataluña central, como una mayor productividad y la capacidad de autoabastecimiento de combustible. El principal objetivo de esta tesis es estudiar la viabilidad ambiental y económica del autoconsumo de aceite vegetal crudo en una explotación agrícola. También se plantea la evaluación social mediante la metodología del análisis de ciclo de vida. A partir de los datos recogidos se define un modelo agrícola parametrizado. Este modelo permite evaluar diferentes escenarios de producción, incluyendo la rotación tradicional (trigo, cebada y barbecho), la rotación actual (trigo y cebada) y la rotación propuesta (colza, trigo y cebada). Además, el modelo tiene en cuenta el procesado de la semilla y el uso de gasóleo o aceite vegetal como carburantes en la maquinaria agrícola. Cabe destacar que el modelo propuesto no pretende producir OVC para sustituir el gasóleo para el transporte, sino que ofrece la posibilidad de producir el combustible que se consume en una explotación usando una parte de las tierras cultivadas. En el contexto de este modelo se realiza un estudio del procesado mecánico de la colza para la obtención de aceite vegetal y un estudio sobre su adecuación para ser usado como carburante. Primero se analiza el índice de acidez en función de la temperatura de prensado para determinar el punto óptimo de trabajo. Consecutivamente, usando el contenido en fósforo del aceite se estudian los procesos de post-tratamiento del aceite obtenido (filtrado y desgomado). El análisis de ciclo de vida (ACV) es la metodología empleada para evaluar el modelo en las tres vertientes de la sostenibilidad (ambiental, económica y social). Esta metodología permite estudiar procesos productivos de manera exhaustiva y evaluarlos de forma cuantitativa. Se lleva a cabo un ACV ambiental siguiendo la metodología ya desarrollada y se realiza un ACV económico a partir de la guía vigente, a pesar de no existir normativa específica como en el caso del ACV ambiental. La metodología del ACV social aún se encuentra en sus inicios y por lo tanto, aunque se detalla cómo se debe realizar, no se puede completar el ACV social del modelo propuesto. La evaluación ambiental del modelo muestra cierta preferencia por el uso del aceite vegetal crudo frente al gasóleo, aunque todavía se pueden optimizar y ajustar los motores térmicos para utilizar el aceite vegetal y ajustar sus emisiones. El rendimiento de la fase de prensado y origen de la electricidad consumida también son puntos que tienen una gran influencia en los resultados. Estos factores son clave para reducir los impactos ambientales en el modelo propuesto. A partir de la evaluación económica se detecta un claro interés económico para introducir la colza en la rotación de cultivos actual. Por otra parte, el procesado de la colza y el uso de la OVC representan económicamente una pequeña disminución en el beneficio (8,0%). Esta diferencia queda reducida a menos de la mitad si el gasóleo agrícola no se subvenciona y se tienen en cuenta las emisiones de CO2 en función del mercado del carbono. Estas improbables medidas políticas pueden favorecer la viabilidad económica del modelo propuesto. Por otra parte, el modelo proporciona una menor dependencia frente a las variaciones del precio de mercado del gasóleo. Finalmente, en el contexto de desarrollo actual de la metodología de evaluación social, se definen nuevos indicadores y se plantea el cálculo de una categoría de impacto social a partir del cálculo de sus correspondientes indicadores. Para futuros estudios sería interesante disponer de una metodología de ACV social bien desarrollada para poder evaluar el modelo propuesto frente al modelo actual, ya que es en la parte social donde se intuyen las mayores diferencias entre los dos sistemas estudiados.

  • Viabilitat tècnica i ambiental de biocombustibles: oli de colza i estella forestal  Open access

     Esteban Dalmau, Bernat
    Defense's date: 2011-07-06
    Department of Mechanical Engineering, Universitat Politècnica de Catalunya
    Theses

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    La dependència actual dels combustibles fòssils en la majoria de sectors industrials i domèstics no és sostenible ni a curt ni a llarg termini. Això està obligant a plantejar alternatives a la majoria de sectors industrials especialment encaminades a l’estalvi energètic i la utilització d’energies renovables. A més a més en el cas dels combustibles, la Unió Europea està incentivant l’ús de biocarburants degut als compromisos assumits en el protocol de Kyoto. Els biocarburants més comuns pel cas del transport són el biodièsel i el bioetanol, que en la majoria dels casos, es produeixen a gran escala i presenten seriosos problemes ambientals i socials tal i com citen els treballs de diversos autors. En aquest escenari és interessant proposar i avaluar ambientalment altres biocarburants no presents actualment en el mercat. En aquesta tesi es proposen i s’avaluen ambientalment (mitjançant l’anàlisi del cicle de vida, ACV) dos biocombustibles, l’oli de colza pel cas del transport, comparat amb la seva conversió a biodièsel i l’estella forestal per a calefacció comparada amb el gasoil. En l’últim apartat d’aquesta tesi es realitza una caracterització de sis olis vegetals, per tal de determinar la temperatura òptima de preescalfament per ser utilitzats com a biocombustibles en motors dièsel actuals. Conjuntament amb aquesta caracterització es parametritza la densitat, viscositat i tensió superficial d’aquests olis en funció de la temperatura.

    La dependencia actual de los combustibles fósiles en la mayoría de sectores industriales y domésticos no es sostenible ni a corto ni a largo plazo. Esto está obligando a plantear alternativas a la mayoría de sectores industriales especialmente encaminados al ahorro energético y la utilización de energías renovables. Además en el caso de los combustibles, la Unión Europea está incentivando el uso de biocarburantes debido a los compromisos asumidos en el protocolo de Kioto. Los biocarburantes más comunes en el caso del transporte son el biodiesel y el bioetanol, que en la mayoría de los casos, se producen a gran escala y presentan serios problemas ambientales y sociales tal y como citan los trabajos de varios autores. En este escenario es interesante proponer y evaluar ambientalmente otros biocarburantes no presentes actualmente en el mercado. En esta tesis se proponen y se evalúan ambientalmente (mediante el análisis del ciclo de vida, ACV) dos biocombustibles, el aceite de colza por el caso del transporte, comparado con su conversión a biodiesel i l' forestal para calefacción comparada con el gasóleo. En el último apartado de esta tesis se realiza una caracterización de seis aceites vegetales, para determinar la temperatura óptima de precalentamiento para ser utilizados como biocombustibles en motores diesel actuales. Conjuntamente con esta caracterización se parametriza la densidad, viscosidad y tensión superficial de estos aceites en función de la temperatura

    The current dependence on fossil fuels in most industrial and domestic sectors is not sustainable in neither short nor long term. This is promoting alternatives to most industries, especially focused on saving energy and using renewable energy. Moreover, the European Union is encouraging the use of biofuels trough the commitments in the Kyoto Protocol. The most common biofuels for transport are biodiesel and bioethanol, which in most cases, are large scale produced and involve serious environmental and social problems according to several authors. In this scenario it is interesting to evaluate other alternative fuels, being environmentally friendly and not currently present in the market. This thesis presents and environmentally analyses two biofuels using life cycle assessment (LCA) methodology. One is straight vegetable rapeseed oil used for truck transport compared to rapeseed biodiesel. The other is wood chips for heating compared to diesel as heating fuel. In the last section of this PjD a characterization of six vegetable oils is performed in order to determine the optimal preheating temperature to use it as biofuel in current diesel engines. Together with this characterization, the density, the viscosity and the surface tension of different vegetable oils are parameterized for a wide range of temperature.

  • INTELLIGENT MONITORING SYSTEM BASED ON ACCOUSTIC EMISSIONS SENSING FOR PLANT CONDITION MONITORING AND PREVENTATIVE MAINTENANCE

     Ortega Redondo, Juan Antonio; Moreno Eguilaz, Juan Manuel; Garcia Espinosa, Antonio; Cusido Roura, Jordi; Riba Ruiz, Jordi Roger; Sala Caselles, Vicente Miguel; Delgado Prieto, Miguel; Romeral Martinez, Jose Luis
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  • Diseño térmico de un motor SRM de 30 kw.

     Riba Ruiz, Jordi Roger
    Date: 2011-02-25
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