Auf Basis umfangreicher Messdatensätze experimentell und numerisch validierte Regeln zur optimierten Auslegung von Luft-Erdwärmetauschern

Ein Luft-Erdwärmetauscher (L-EWT) kommt wegen seines niedrigen Energiebedarfs und möglicher guter Aufwandszahlen als umweltfreundliche Versorgungskomponente für Gebäude in Betracht. Dabei ist besonders vorteilhaft, dass ein L-EWT die Umgebungsluft je nach Jahreszeit vorwärmen oder auch kühlen kann. Dem zufolge sind L-EWT zur Energieeinsparung nicht nur für den Wohnhausbau interessant, sondern auch dort, wo immer noch große Mengen an fossiler Energie für die Raumkühlung benötigt werden, im Büro- und Produktionsgebäudesektor. Der Einsatzbereich eines L-EWT liegt zwischen Volumenströmen von 100 m3/h und mehreren 100.000 m3/h. Aus dieser Bandbreite und den instationären Randbedingungen entstehen erhebliche Schwierigkeiten, allgemeingültige Aussagen über das zu erwartende thermische Systemverhalten aus der Vielzahl möglicher Konstruktionsvarianten zu treffen. Hauptziel dieser Arbeit ist es, auf Basis umfangreicher, mehrjähriger Messungen an einer eigens konzipierten Testanlage und eines speziell angepassten numerischen Rechenmodells, Kennzahlen zu entwickeln, die es ermöglichen, die Betriebseigenschaften eines L-EWT im Planungsalltag zu bestimmen und ein technisch, ökologisch wie ökonomisch effizientes System zu identifizieren. Es werden die Kennzahlen elewt (Aufwandszahl), QV (Netto-Volumenleistung), ME (Meterertrag), sowie die Kombination aus v (Strömungsgeschwindigkeit) und VL (Metervolumenstrom) definiert, die zu wichtigen Informationen führen, mit denen die Qualität von Systemvarianten in der Planungsphase bewertet werden können. Weiterführende Erkenntnisse über die genauere Abschätzung von Bodenkennwerten werden dargestellt. Die hygienische Situation der durch den L-EWT transportierten Luft wird für die warme Jahreszeit, aufgrund auftretender Tauwasserbildung, beschrieben. Aus diesem Grund werden alle relevanten lufthygienischen Parameter in mehreren aufwendigen Messkampagnen erfasst und auf pathogene Wirkungen überprüft. Es wird über Sensitivitätsanalysen gezeigt, welche Fehler bei Annahme falscher Randbedingungen eintreten. Weiterhin werden in dieser Arbeit wesentliche, grundsätzliche Erkenntnisse aufbereitet, die sich aus der Betriebsbeobachtung und der Auswertung der umfangreich vorliegenden Messdaten mehrerer Anlagen ergeben haben und für die praktische Umsetzung und die Betriebsführung bedeutend sind. Hinweise zu Materialeigenschaften und zur Systemwirtschaftlichkeit sind detailliert aufgeführt.

Investigación en el aula : las decisiones condicionan las interacciones.

Se estudia las consecuencias de las decisiones de diseño de una investigación en las interacciones que posteriormente se producen entre investigador y sujeto. Se trabaja sobre el ejemplo de una investigación sobre el aprendizaje de los números reales y su representación en la recta. Dicha investigación se realiza sobre alumnos de primer y segundo curso de bachiller, así como de primer curso de licenciatura en matemáticas. Se decide dividir la investigación en tres estudios. El primero es una análisis preliminar sobre los números reales. El segundo es el trabajo de campo con estudiantes. El último es un análisis de los resultados obtenidos y el historial de decisiones de la investigación. La muestra de sujetos de la investigación consta de varios estudiantes de secundaria y primer curso de licenciatura que no han podido ser elegidos por los investigadores. La fase empírica de la investigación consiste en la proposición de una serie de tests a los alumnos. La primera parte del estudio con alumnos se realiza en el aula. Una vez realizados los test en grupo, se hacen entrevistas individuales en una habitación aparte. Durante dichas entrevistas, la labor del investigador es fundamentalmente dejarle claro al alumno que el test no va a ser evaluado ni tendrá repercusión en su currículum. Se observa que la comunicación con los alumnos logra aumentar la fiabilidad del estudio tranquilizando a los estudiantes.

Designing single event upset mitigation techniques for large SRAM-Based FPGA components

This thesis presents the study and development of fault-tolerant techniques for programmable architectures, the well-known Field Programmable Gate Arrays (FPGAs), customizable by SRAM. FPGAs are becoming more valuable for space applications because of the high density, high performance, reduced development cost and re-programmability. In particular, SRAM-based FPGAs are very valuable for remote missions because of the possibility of being reprogrammed by the user as many times as necessary in a very short period. SRAM-based FPGA and micro-controllers represent a wide range of components in space applications, and as a result will be the focus of this work, more specifically the Virtex® family from Xilinx and the architecture of the 8051 micro-controller from Intel. The Triple Modular Redundancy (TMR) with voters is a common high-level technique to protect ASICs against single event upset (SEU) and it can also be applied to FPGAs. The TMR technique was first tested in the Virtex® FPGA architecture by using a small design based on counters. Faults were injected in all sensitive parts of the FPGA and a detailed analysis of the effect of a fault in a TMR design synthesized in the Virtex® platform was performed. Results from fault injection and from a radiation ground test facility showed the efficiency of the TMR for the related case study circuit. Although TMR has showed a high reliability, this technique presents some limitations, such as area overhead, three times more input and output pins and, consequently, a significant increase in power dissipation. Aiming to reduce TMR costs and improve reliability, an innovative high-level technique for designing fault-tolerant systems in SRAM-based FPGAs was developed, without modification in the FPGA architecture. This technique combines time and hardware redundancy to reduce overhead and to ensure reliability. It is based on duplication with comparison and concurrent error detection. The new technique proposed in this work was specifically developed for FPGAs to cope with transient faults in the user combinational and sequential logic, while also reducing pin count, area and power dissipation. The methodology was validated by fault injection experiments in an emulation board. The thesis presents comparison results in fault coverage, area and performance between the discussed techniques.

Comparação do desempenho de duas bombas acopladas diretamente a geradores fotovoltaicos

No Brasil, assim como em outros países que recebem abundantes quantidades de radiação solar durante todo o ano, há um grande potencial para os sistemas que usam a tecnologia fotovoltaica para promover o bombeamento de água. Entretanto, a escolha dos conjuntos de motores e bombas mais adequados para cada situação passa pela análise do desempenho dos sistemas de bombeamento. Portanto, devem ser analisadas tanto as melhores configurações de geradores fotovoltaicos destinados a operar os conjuntos formados pelos motores e bombas, quanto às eficiências das bombas e da conversão fotovoltaica. Nesse trabalho são apresentadas medidas e comparações do desempenho de dois sistemas de bombeamento diretamente acoplados a geradores fotovoltaicos. Para tanto, foi construída uma bancada destinada a realizar uma série de experimentos. Um dos sistemas usou uma bomba centrífuga acoplada a um gerador fotovoltaico formado por três módulos fotovoltaicos. O outro, utilizou uma bomba volumétrica de diafragma acoplada a um único módulo fotovoltaico. Os experimentos foram conduzidos em duas etapas distintas. A primeira foi feita com os motores acoplados a uma fonte de potência em corrente contínua e serviu para a determinação das curvas de desempenho de cada uma das bombas, das curvas dos sistemas, assim como das curvas de corrente (I) e de tensão (V) de cada um dos motores que acionavam as bombas. A segunda foi realizada com os sistemas acoplados diretamente aos geradores fotovoltaicos. A determinação da configuração dos geradores fotovoltaicos destinados a acionar os diferentes sistemas de bombeamento em análise nesse trabalho foi feita por meio da sobreposição das curvas de corrente e tensão dos motores e dos módulos fotovoltaicos. A parte experimental, estando os sistemas acoplados aos geradores, constou de medidas realizadas em intervalos de tempo de cinco segundos, para cada bomba e em várias alturas, das seguintes variáveis: temperatura ambiente, irradiância, temperatura dos módulos, corrente e tensão do motor, rotação do motor, temperatura da água, diferencial de pressão entre entrada e saída da bomba e vazão. As diversas alturas foram simuladas por meio da abertura e/ou fechamento de uma válvula de controle de vazão colocada na extremidade tubulação de descarga, operada manualmente. Os procedimentos adotados nessa dissertação permitiram caracterizar os sistemas de bombeamento propostos, assim como determinar quais os arranjos mais adequados para operar cada sistema. Verificou-se que o melhor arranjo para operar o conjunto motor e bomba centrífuga foi aquele formado por três módulos fotovoltaicos ligados em paralelo, enquanto que a melhor opção para operar o conjunto motor e bomba de diafragma foi com somente um módulo fotovoltaico. De posse dos dados medidos foi possível determinar as eficiências: instantâneas, máximas instantâneas e diárias da conversão fotovoltaica assim como dos conjuntos motores e bombas, em diferentes alturas. Relativamente à conversão fotovoltaica, verificou-se que o conjunto motor e bomba centrífuga operou com eficiência instantânea máxima de 5,74% e eficiência diária de 4,70%, enquanto que o conjunto motor e bomba volumétrica de diafragma operou com eficiência instantânea máxima de 7,66% e eficiência diária de 5,82%. Relativamente à eficiência dos conjuntos motores e bombas, verificou-se que o conjunto motor e bomba centrífuga operou com eficiência instantânea máxima de 19,19% e eficiência diária de 16,79%, enquanto que o conjunto motor e bomba volumétrica de diafragma operou com eficiência instantânea máxima de 38,88% e eficiência diária de 34,30%. Verificou-se ainda que a altura foi determinante na eficiência do conjunto motor e bomba centrífuga e pouco influenciou na eficiência do conjunto motor e bomba de diafragma. Além dessas, outras considerações sobre o comportamento dos sistemas de bombeamento ao longo de um dia também foram ser registrados, tais como: limiares de irradiância para início e final de vazão, correntes de pico ou de arranque dos motores e correntes de início de vazão ou escoamento.

Fault current limiter using transformer and modular device of YBCO coated conductor

In this work, we report on the evaluation of a superconducting fault current limiter (SFCL). It is consisted of a modular superconducting device combined with a short-circuited transformer with a primary copper winding connected in series to the power line and the secondary side short-circuited by the superconducting device. The basic idea is adding a magnetic component to contribute to the current limitation by the impedance reflected to the line after transition of the superconducting device. The evaluation tests were performed with a prospective current up to 2 kA, with the short-circuited transformer of 2.5 kVA, 220 V/660 V connected to a test facility of 100 kVA power capacity. The resistive SFCL using a modular superconducting device was tested without degradation for a prospective fault current of 1.8 kA, achieving the limiting factor 2.78; the voltage achieved 282 V corresponding to an electric field of 11 V/m. The test performed with the combined SFCL (xsuperconducting device + transformer) using series and toroidal transformers showed current limiting factor of 3.1 and 2 times, respectively. The test results of the combined SFCL with short-circuited transformer showed undesirable influence of the transformer impedance, resulting in reduction of the fault current level. © 2002-2011 IEEE.

Pulsação de conjudado em motores monofásicos de capacitor permanente alimentados por tensões não senoidais

Pós-graduação em Engenharia Elétrica - FEB

Feasibility Study of Solar Driven Underground Cooling System

In the United States the peak electrical use occurs during the summer. In addition, the building sector consumes a major portion of the annual electrical energy consumption. One of the main energy consuming components in the building sector is the Heating, Ventilation, and Air-Conditioning (HVAC) systems. This research studies the feasibility of implementing a solar driven underground cooling system that could contribute to reducing building cooling loads. The developed system consists of an Earth-to-Air Heat Exchanger (EAHE) coupled with a solar chimney that provides a natural cool draft to the test facility building at the Solar Energy Research Test Facility in Omaha, Nebraska. Two sets of tests have been conducted: a natural passively driven airflow test and a forced fan assisted airflow test. The resulting data of the tests has been analyzed to study the thermal performance of the implemented system. Results show that: The underground soil proved to be a good heat sink at a depth of 9.5ft, where its temperature fluctuates yearly in the range of (46.5°F-58.2°F). Furthermore, the coupled system during the natural airflow modes can provide good thermal comfort conditions that comply with ASHRAE standard 55-2004. It provided 0.63 tons of cooling, which almost covered the building design cooling load (0.8 tons, extreme condition). On the other hand, although the coupled system during the forced airflow mode could not comply with ASHRAE standard 55-2004, it provided 1.27 tons of cooling which is even more than the building load requirements. Moreover, the underground soil experienced thermal saturation during the forced airflow mode due to the oversized fan, which extracted much more airflow than the EAHE ability for heat dissipation and the underground soil for heat absorption. In conclusion, the coupled system proved to be a feasible cooling system, which could be further improved with a few design recommendations.

Aufbau und Inbetriebnahme eines hochsensitiven 3-He-Magnetometers für ein zukünftiges Experiment zur Bestimmung eines elektrischen Dipolmoments des freien Neutrons

Die Messung eines möglichen elektrischen Dipolmoments des freien Neutrons erfordert genaustmögliche Kenntnis und Überwachung des magnetischen Feldes im Inneren der n2EDM-Spektrometerkammer. Die freie Spinpräzession von hyperpolarisiertem ³He kann verbunden mit einer Signalauslese mittels optisch gepumpter Cs-Magnetometer dazu genutzt werden, Messempfindlichkeit auf Magnetfeldschwankungen im Bereich weniger Femto-Tesla zu erhalten. Am Institut für Physik der Universität Mainz wurde eine ³He/Cs-Testanlage aufgebaut, um die Möglichkeiten der Signalauslese der ³He-Spinpräzession mittels eines lampengepumpten Cs-Magnetometers zu untersuchen. Darüber hinaus wurde eine ultrakompakte und transportable Polarisationseinheit entwickelt und installiert, welche ermöglicht, eine ³He-Hyperpolarisation von bis zu 55 Prozent zu erreichen. Im Anschluss wird das polarisierte 3He-Gas automatisiert komprimiert und in zwei Magnetometerzellen in Sandwichanordnung innerhalb der n2EDM-Spektrometerkammer gefüllt. In dieser Arbeit werden die Ergebnisse der ersten im Januar 2012 erfolgreich durchgeführten Messungen vorgestellt. Bei diesen Messungen wurde ³He-Gas in der ultrakompakten Polarisationseinheit hyperpolarisiert und über Führungsfelder eines Transfersystems in eine vierlagige Mumetall-Abschirmung transferiert. Im Anschluss konnte im Inneren der magnetischen Abschirmung die freie ³He-Spinpräzession mittels eines lampengepumpten Cs-Magnetometer eindeutig nachgewiesen werden.

FEM and experimental analysis of a wind turbine blade

This paperwork compares the a numerical validation of the finite element model (FEM) with respect the experimental tests of a new generation wind turbine blade designed by TPI Composites Inc. called BSDS (Blade System Design Study). The research is focused on the analysis by finite element (FE) of the BSDS blade and its comparison with respect the experimental data from static and dynamic investigations. The goal of the research is to create a general procedure which is based on a finite element model and will be used to create an accurate digital copy for any kind of blade. The blade prototype was created in SolidWorks and the blade of Sandia National Laboratories Blade System Design Study was accurately reproduced. At a later stage the SolidWorks model was imported in Ansys Mechanical APDL where the shell geometry was created and modal, static and fatigue analysis were carried out. The outcomes of the FEM analysis were compared with the real test on the BSDS blade at Clarkson University laboratory carried out by a new procedures called Blade Test Facility that includes different methods for both the static and dynamic test of the wind turbine blade. The outcomes from the FEM analysis reproduce the real behavior of the blade subjected to static loads in a very satisfying way. A most detailed study about the material properties could improve the accuracy of the analysis.

Effect of segmented anodes on the performance and plume of a hall thruster

Development of alternative propellants for Hall thruster operation is an active area of research. Xenon is the current propellant of choice for Hall thrusters, but can be costly in large thrusters and for extended test periods. Condensible propellants may offer an alternative to xenon, as they will not require costly active pumping to remove from a test facility, and may be less expensive to purchase. A method has been developed which uses segmented electrodes in the discharge channel of a Hall thruster to divert discharge current to and from the main anode and thus control the anode temperature. By placing a propellant reservoir in the anode, the evaporation rate, and hence, mass flow of propellant can be controlled. Segmented electrodes for thermal control of a Hall thruster represent a unique strategy of thruster design, and thus the performance of the thruster must be measured to determine the effect the electrodes have on the thruster. Furthermore, the source of any changes in thruster performance due to the adjustment of discharge current between the shims and the main anode must be characterized. A Hall thruster was designed and constructed with segmented electrodes. It was then tested at anode voltages between 300 and 400 V and mass flows between 4 and 6 mg/s, as well as 100%, 75%, 50%, 25%, and <5% of the discharge current on the shim electrodes. The level of current on the shims was adjusted by changing the shim voltage. At each operating point, the thruster performance, plume divergence, ion energy, and multiply charged ion fraction were measured performance exhibited a small change with the level of discharge current on the shim electrodes. Thrust and specific impulse increased by as much as 6% and 7.7%, respectively, as discharge current was shifted from the main anode to the shims at constant anode voltage. Thruster efficiency did not change. Plume divergence was reduced by approximately 4 degrees of half-angle at high levels of current on the shims and at all combinations of mass flow and anode voltage. The fraction of singly charged xenon in the thruster plume varied between approximately 80% and 95% as the anode voltage and mass flow were changed, but did not show a significant change with shim current. Doubly and triply charged xenon made up the remainder of the ions detected. Ion energy exhibited a mixed behavior. The highest voltage present in the thruster largely dictated the most probable energy; either shim or anode voltage, depending on which was higher. The overall change in most probable ion energy was 20-30 eV, the majority of which took place while the shim voltage was higher than the anode voltage. The thrust, specific impulse, plume divergence, and ion energy all indicate that the thruster is capable of a higher performance output at high levels of discharge current on the shims. The lack of a change in efficiency and fraction of multiply charged ions indicate that the thruster can be operated at any level of current on the shims without detrimental effect, and thus a condensible propellant thruster can control the anode temperature without a decrease in efficiency or a change in the multiply charged ion fraction.

Distributed Control Nodes for Material Flow System Controls on the Example of Unit Load Conveyor and Sorter Facilities

The Chair of Transportation and Ware-housing at the University of Dortmund together with its industrial partner has developed and implemented a decentralized control system based on embedded technology and Internet standards. This innovative, highly flexible system uses autonomous software modules to control the flow of unit loads in real-time. The system is integrated into Chair’s test facility consisting of a wide range of conveying and sorting equipment. It is built for proof of concept purposes and will be used for further research in the fields of decentralized automation and embedded controls. This presentation describes the implementation of this decentralized control system.

Accident Management Actions In An Upper-Head Small-Break Loss-Of-Coolant Accident With High-Pressure Safety Injection Failed

Since the Three Mile Island accident, an important focus of pressurized water reactor (PWR) transient analyses has been a small-break loss-of-coolant accident (SBLOCA). In 2002, the discovery of thinning of the vessel head wall at the Davis Besse nuclear power plant reactor indicated the possibility of an SBLOCA in the upper head of the reactor vessel as a result of circumferential cracking of a control rod drive mechanism penetration nozzle - which has cast even greater importance on the study of SBLOCAs. Several experimental tests have been performed at the Large Scale Test Facility to simulate the behavior of a PWR during an upper-head SBLOCA. The last of these tests, Organisation for Economic Co-operation and Development Nuclear Energy Agency Rig of Safety Assessment (OECD/NEA ROSA) Test 6.1, was performed in 2005. This test was simulated with the TRACE 5.0 code, and good agreement with the experimental results was obtained. Additionally, a broad analysis of an upper-head SBLOCA with high-pressure safety injection failed in a Westinghouse PWR was performed taking into account different accident management actions and conditions in order to check their suitability. This issue has been analyzed also in the framework of the OECD/NEA ROSA project and the Code Applications and Maintenance Program (CAMP). The main conclusion is that the current emergency operating procedures for Westinghouse reactor design are adequate for these kinds of sequences, and they do not need to be modified.

Experimental and numerical assessment of the aeroelastic stability of blade pair packages

The stabilizing effect of grouping rotor blades in pairs has been assessed both, numerically and experimentally. The bending and torsion modes of a low aspect ratio high speed turbine cascade tested in the non-rotating test facility at EPFL (Ecole Polytechnique Fédérale de Lausanne) have been chosen as the case study. The controlled vibration of 20 blades in travelling wave form was performed by means of an electromagnetic excitation system, enabling the adjustement of the vibration amplitude and inter blade phase at a given frequency. Unsteady pressure transducers located along the blade mid-section were used to obtain the modulus and phase of the unsteady pressure caused by the airfoil motion. The stabilizing effect of the torsion mode was clearly observed both in the experiments and the simulations, however the effect of grouping the blades in pairs in the minimum damping at the tested frequency was marginal in the bending mode. A numerical tool was validated using the available experimental data and then used to extend the results at lower and more relevant reduced frequencies. It is shown that the stabilizing effect exists for the bending and torsion modes in the frequency range typical of low-pressure turbines. It is concluded that the stabilizing effect of this configuration is due to the shielding effect of the pressure side of the airfoil that defines the passage of the pair on the suction side of the same passage, since the relative motion between both is null. This effect is observed both in the experiments and simulations.

Método experimental para la caracterización de las diferentes tecnologías de integración arquitectónica de la energía fotovoltaica en condiciones de funcionamiento real = Experimental method for characterization of several building integrated photovoltaic technologies under real working conditions

Hoy en día, el proceso de un proyecto sostenible persigue realizar edificios de elevadas prestaciones que son, energéticamente eficientes, saludables y económicamente viables utilizando sabiamente recursos renovables para minimizar el impacto sobre el medio ambiente reduciendo, en lo posible, la demanda de energía, lo que se ha convertido, en la última década, en una prioridad. La Directiva 2002/91/CE "Eficiencia Energética de los Edificios" (y actualizaciones posteriores) ha establecido el marco regulatorio general para el cálculo de los requerimientos energéticos mínimos. Desde esa fecha, el objetivo de cumplir con las nuevas directivas y protocolos ha conducido las políticas energéticas de los distintos países en la misma dirección, centrándose en la necesidad de aumentar la eficiencia energética en los edificios, la adopción de medidas para reducir el consumo, y el fomento de la generación de energía a través de fuentes renovables. Los edificios de energía nula o casi nula (ZEB, Zero Energy Buildings ó NZEB, Net Zero Energy Buildings) deberán convertirse en un estándar de la construcción en Europa y con el fin de equilibrar el consumo de energía, además de reducirlo al mínimo, los edificios necesariamente deberán ser autoproductores de energía. Por esta razón, la envolvente del edifico y en particular las fachadas son importantes para el logro de estos objetivos y la tecnología fotovoltaica puede tener un papel preponderante en este reto. Para promover el uso de la tecnología fotovoltaica, diferentes programas de investigación internacionales fomentan y apoyan soluciones para favorecer la integración completa de éstos sistemas como elementos arquitectónicos y constructivos, los sistemas BIPV (Building Integrated Photovoltaic), sobre todo considerando el próximo futuro hacia edificios NZEB. Se ha constatado en este estudio que todavía hay una falta de información útil disponible sobre los sistemas BIPV, a pesar de que el mercado ofrece una interesante gama de soluciones, en algunos aspectos comparables a los sistemas tradicionales de construcción. Pero por el momento, la falta estandarización y de una regulación armonizada, además de la falta de información en las hojas de datos técnicos (todavía no comparables con las mismas que están disponibles para los materiales de construcción), hacen difícil evaluar adecuadamente la conveniencia y factibilidad de utilizar los componentes BIPV como parte integrante de la envolvente del edificio. Organizaciones internacionales están trabajando para establecer las normas adecuadas y procedimientos de prueba y ensayo para comprobar la seguridad, viabilidad y fiabilidad estos sistemas. Sin embargo, hoy en día, no hay reglas específicas para la evaluación y caracterización completa de un componente fotovoltaico de integración arquitectónica de acuerdo con el Reglamento Europeo de Productos de la Construcción, CPR 305/2011. Los productos BIPV, como elementos de construcción, deben cumplir con diferentes aspectos prácticos como resistencia mecánica y la estabilidad; integridad estructural; seguridad de utilización; protección contra el clima (lluvia, nieve, viento, granizo), el fuego y el ruido, aspectos que se han convertido en requisitos esenciales, en la perspectiva de obtener productos ambientalmente sostenibles, saludables, eficientes energéticamente y económicamente asequibles. Por lo tanto, el módulo / sistema BIPV se convierte en una parte multifuncional del edificio no sólo para ser física y técnicamente "integrado", además de ser una oportunidad innovadora del diseño. Las normas IEC, de uso común en Europa para certificar módulos fotovoltaicos -IEC 61215 e IEC 61646 cualificación de diseño y homologación del tipo para módulos fotovoltaicos de uso terrestre, respectivamente para módulos fotovoltaicos de silicio cristalino y de lámina delgada- atestan únicamente la potencia del módulo fotovoltaico y dan fe de su fiabilidad por un período de tiempo definido, certificando una disminución de potencia dentro de unos límites. Existe también un estándar, en parte en desarrollo, el IEC 61853 (“Ensayos de rendimiento de módulos fotovoltaicos y evaluación energética") cuyo objetivo es la búsqueda de procedimientos y metodologías de prueba apropiados para calcular el rendimiento energético de los módulos fotovoltaicos en diferentes condiciones climáticas. Sin embargo, no existen ensayos normalizados en las condiciones específicas de la instalación (p. ej. sistemas BIPV de fachada). Eso significa que es imposible conocer las efectivas prestaciones de estos sistemas y las condiciones ambientales que se generan en el interior del edificio. La potencia nominal de pico Wp, de un módulo fotovoltaico identifica la máxima potencia eléctrica que éste puede generar bajo condiciones estándares de medida (STC: irradición 1000 W/m2, 25 °C de temperatura del módulo y distribución espectral, AM 1,5) caracterizando eléctricamente el módulo PV en condiciones específicas con el fin de poder comparar los diferentes módulos y tecnologías. El vatio pico (Wp por su abreviatura en inglés) es la medida de la potencia nominal del módulo PV y no es suficiente para evaluar el comportamiento y producción del panel en términos de vatios hora en las diferentes condiciones de operación, y tampoco permite predecir con convicción la eficiencia y el comportamiento energético de un determinado módulo en condiciones ambientales y de instalación reales. Un adecuado elemento de integración arquitectónica de fachada, por ejemplo, debería tener en cuenta propiedades térmicas y de aislamiento, factores como la transparencia para permitir ganancias solares o un buen control solar si es necesario, aspectos vinculados y dependientes en gran medida de las condiciones climáticas y del nivel de confort requerido en el edificio, lo que implica una necesidad de adaptación a cada contexto específico para obtener el mejor resultado. Sin embargo, la influencia en condiciones reales de operación de las diferentes soluciones fotovoltaicas de integración, en el consumo de energía del edificio no es fácil de evaluar. Los aspectos térmicos del interior del ambiente o de iluminación, al utilizar módulos BIPV semitransparentes por ejemplo, son aún desconocidos. Como se dijo antes, la utilización de componentes de integración arquitectónica fotovoltaicos y el uso de energía renovable ya es un hecho para producir energía limpia, pero también sería importante conocer su posible contribución para mejorar el confort y la salud de los ocupantes del edificio. Aspectos como el confort, la protección o transmisión de luz natural, el aislamiento térmico, el consumo energético o la generación de energía son aspectos que suelen considerarse independientemente, mientras que todos juntos contribuyen, sin embargo, al balance energético global del edificio. Además, la necesidad de dar prioridad a una orientación determinada del edificio, para alcanzar el mayor beneficio de la producción de energía eléctrica o térmica, en el caso de sistemas activos y pasivos, respectivamente, podría hacer estos últimos incompatibles, pero no necesariamente. Se necesita un enfoque holístico que permita arquitectos e ingenieros implementar sistemas tecnológicos que trabajen en sinergia. Se ha planteado por ello un nuevo concepto: "C-BIPV, elemento fotovoltaico consciente integrado", esto significa necesariamente conocer los efectos positivos o negativos (en términos de confort y de energía) en condiciones reales de funcionamiento e instalación. Propósito de la tesis, método y resultados Los sistemas fotovoltaicos integrados en fachada son a menudo soluciones de vidrio fácilmente integrables, ya que por lo general están hechos a medida. Estos componentes BIPV semitransparentes, integrados en el cerramiento proporcionan iluminación natural y también sombra, lo que evita el sobrecalentamiento en los momentos de excesivo calor, aunque como componente estático, asimismo evitan las posibles contribuciones pasivas de ganancias solares en los meses fríos. Además, la temperatura del módulo varía considerablemente en ciertas circunstancias influenciada por la tecnología fotovoltaica instalada, la radiación solar, el sistema de montaje, la tipología de instalación, falta de ventilación, etc. Este factor, puede suponer un aumento adicional de la carga térmica en el edificio, altamente variable y difícil de cuantificar. Se necesitan, en relación con esto, más conocimientos sobre el confort ambiental interior en los edificios que utilizan tecnologías fotovoltaicas integradas, para abrir de ese modo, una nueva perspectiva de la investigación. Con este fin, se ha diseñado, proyectado y construido una instalación de pruebas al aire libre, el BIPV Env-lab "BIPV Test Laboratory", para la caracterización integral de los diferentes módulos semitransparentes BIPV. Se han definido también el método y el protocolo de ensayos de caracterización en el contexto de un edificio y en condiciones climáticas y de funcionamiento reales. Esto ha sido posible una vez evaluado el estado de la técnica y la investigación, los aspectos que influyen en la integración arquitectónica y los diferentes tipos de integración, después de haber examinado los métodos de ensayo para los componentes de construcción y fotovoltaicos, en condiciones de operación utilizadas hasta ahora. El laboratorio de pruebas experimentales, que consiste en dos habitaciones idénticas a escala real, 1:1, ha sido equipado con sensores y todos los sistemas de monitorización gracias a los cuales es posible obtener datos fiables para evaluar las prestaciones térmicas, de iluminación y el rendimiento eléctrico de los módulos fotovoltaicos. Este laboratorio permite el estudio de tres diferentes aspectos que influencian el confort y consumo de energía del edificio: el confort térmico, lumínico, y el rendimiento energético global (demanda/producción de energía) de los módulos BIPV. Conociendo el balance de energía para cada tecnología solar fotovoltaica experimentada, es posible determinar cuál funciona mejor en cada caso específico. Se ha propuesto una metodología teórica para la evaluación de estos parámetros, definidos en esta tesis como índices o indicadores que consideran cuestiones relacionados con el bienestar, la energía y el rendimiento energético global de los componentes BIPV. Esta metodología considera y tiene en cuenta las normas reglamentarias y estándares existentes para cada aspecto, relacionándolos entre sí. Diferentes módulos BIPV de doble vidrio aislante, semitransparentes, representativos de diferentes tecnologías fotovoltaicas (tecnología de silicio monocristalino, m-Si; de capa fina en silicio amorfo unión simple, a-Si y de capa fina en diseleniuro de cobre e indio, CIS) fueron seleccionados para llevar a cabo una serie de pruebas experimentales al objeto de demostrar la validez del método de caracterización propuesto. Como resultado final, se ha desarrollado y generado el Diagrama Caracterización Integral DCI, un sistema gráfico y visual para representar los resultados y gestionar la información, una herramienta operativa útil para la toma de decisiones con respecto a las instalaciones fotovoltaicas. Este diagrama muestra todos los conceptos y parámetros estudiados en relación con los demás y ofrece visualmente toda la información cualitativa y cuantitativa sobre la eficiencia energética de los componentes BIPV, por caracterizarlos de manera integral. ABSTRACT A sustainable design process today is intended to produce high-performance buildings that are energy-efficient, healthy and economically feasible, by wisely using renewable resources to minimize the impact on the environment and to reduce, as much as possible, the energy demand. In the last decade, the reduction of energy needs in buildings has become a top priority. The Directive 2002/91/EC “Energy Performance of Buildings” (and its subsequent updates) established a general regulatory framework’s methodology for calculation of minimum energy requirements. Since then, the aim of fulfilling new directives and protocols has led the energy policies in several countries in a similar direction that is, focusing on the need of increasing energy efficiency in buildings, taking measures to reduce energy consumption, and fostering the use of renewable sources. Zero Energy Buildings or Net Zero Energy Buildings will become a standard in the European building industry and in order to balance energy consumption, buildings, in addition to reduce the end-use consumption should necessarily become selfenergy producers. For this reason, the façade system plays an important role for achieving these energy and environmental goals and Photovoltaic can play a leading role in this challenge. To promote the use of photovoltaic technology in buildings, international research programs encourage and support solutions, which favors the complete integration of photovoltaic devices as an architectural element, the so-called BIPV (Building Integrated Photovoltaic), furthermore facing to next future towards net-zero energy buildings. Therefore, the BIPV module/system becomes a multifunctional building layer, not only physically and functionally “integrated” in the building, but also used as an innovative chance for the building envelope design. It has been found in this study that there is still a lack of useful information about BIPV for architects and designers even though the market is providing more and more interesting solutions, sometimes comparable to the existing traditional building systems. However at the moment, the lack of an harmonized regulation and standardization besides to the non-accuracy in the technical BIPV datasheets (not yet comparable with the same ones available for building materials), makes difficult for a designer to properly evaluate the fesibility of this BIPV components when used as a technological system of the building skin. International organizations are working to establish the most suitable standards and test procedures to check the safety, feasibility and reliability of BIPV systems. Anyway, nowadays, there are no specific rules for a complete characterization and evaluation of a BIPV component according to the European Construction Product Regulation, CPR 305/2011. BIPV products, as building components, must comply with different practical aspects such as mechanical resistance and stability; structural integrity; safety in use; protection against weather (rain, snow, wind, hail); fire and noise: aspects that have become essential requirements in the perspective of more and more environmentally sustainable, healthy, energy efficient and economically affordable products. IEC standards, commonly used in Europe to certify PV modules (IEC 61215 and IEC 61646 respectively crystalline and thin-film ‘Terrestrial PV Modules-Design Qualification and Type Approval’), attest the feasibility and reliability of PV modules for a defined period of time with a limited power decrease. There is also a standard (IEC 61853, ‘Performance Testing and Energy Rating of Terrestrial PV Modules’) still under preparation, whose aim is finding appropriate test procedures and methodologies to calculate the energy yield of PV modules under different climate conditions. Furthermore, the lack of tests in specific conditions of installation (e.g. façade BIPV devices) means that it is difficult knowing the exact effective performance of these systems and the environmental conditions in which the building will operate. The nominal PV power at Standard Test Conditions, STC (1.000 W/m2, 25 °C temperature and AM 1.5) is usually measured in indoor laboratories, and it characterizes the PV module at specific conditions in order to be able to compare different modules and technologies on a first step. The “Watt-peak” is not enough to evaluate the panel performance in terms of Watt-hours of various modules under different operating conditions, and it gives no assurance of being able to predict the energy performance of a certain module at given environmental conditions. A proper BIPV element for façade should take into account thermal and insulation properties, factors as transparency to allow solar gains if possible or a good solar control if necessary, aspects that are linked and high dependent on climate conditions and on the level of comfort to be reached. However, the influence of different façade integrated photovoltaic solutions on the building energy consumption is not easy to assess under real operating conditions. Thermal aspects, indoor temperatures or luminance level that can be expected using building integrated PV (BIPV) modules are not well known. As said before, integrated photovoltaic BIPV components and the use of renewable energy is already a standard for green energy production, but would also be important to know the possible contribution to improve the comfort and health of building occupants. Comfort, light transmission or protection, thermal insulation or thermal/electricity power production are aspects that are usually considered alone, while all together contribute to the building global energy balance. Besides, the need to prioritize a particular building envelope orientation to harvest the most benefit from the electrical or thermal energy production, in the case of active and passive systems respectively might be not compatible, but also not necessary. A holistic approach is needed to enable architects and engineers implementing technological systems working in synergy. A new concept have been suggested: “C-BIPV, conscious integrated BIPV”. BIPV systems have to be “consciously integrated” which means that it is essential to know the positive and negative effects in terms of comfort and energy under real operating conditions. Purpose of the work, method and results The façade-integrated photovoltaic systems are often glass solutions easily integrable, as they usually are custommade. These BIPV semi-transparent components integrated as a window element provides natural lighting and shade that prevents overheating at times of excessive heat, but as static component, likewise avoid the possible solar gains contributions in the cold months. In addition, the temperature of the module varies considerably in certain circumstances influenced by the PV technology installed, solar radiation, mounting system, lack of ventilation, etc. This factor may result in additional heat input in the building highly variable and difficult to quantify. In addition, further insights into the indoor environmental comfort in buildings using integrated photovoltaic technologies are needed to open up thereby, a new research perspective. This research aims to study their behaviour through a series of experiments in order to define the real influence on comfort aspects and on global energy building consumption, as well as, electrical and thermal characteristics of these devices. The final objective was to analyze a whole set of issues that influence the global energy consumption/production in a building using BIPV modules by quantifying the global energy balance and the BIPV system real performances. Other qualitative issues to be studied were comfort aspect (thermal and lighting aspects) and the electrical behaviour of different BIPV technologies for vertical integration, aspects that influence both energy consumption and electricity production. Thus, it will be possible to obtain a comprehensive global characterization of BIPV systems. A specific design of an outdoor test facility, the BIPV Env-lab “BIPV Test Laboratory”, for the integral characterization of different BIPV semi-transparent modules was developed and built. The method and test protocol for the BIPV characterization was also defined in a real building context and weather conditions. This has been possible once assessed the state of the art and research, the aspects that influence the architectural integration and the different possibilities and types of integration for PV and after having examined the test methods for building and photovoltaic components, under operation conditions heretofore used. The test laboratory that consists in two equivalent test rooms (1:1) has a monitoring system in which reliable data of thermal, daylighting and electrical performances can be obtained for the evaluation of PV modules. The experimental set-up facility (testing room) allows studying three different aspects that affect building energy consumption and comfort issues: the thermal indoor comfort, the lighting comfort and the energy performance of BIPV modules tested under real environmental conditions. Knowing the energy balance for each experimented solar technology, it is possible to determine which one performs best. A theoretical methodology has been proposed for evaluating these parameters, as defined in this thesis as indices or indicators, which regard comfort issues, energy and the overall performance of BIPV components. This methodology considers the existing regulatory standards for each aspect, relating them to one another. A set of insulated glass BIPV modules see-through and light-through, representative of different PV technologies (mono-crystalline silicon technology, mc-Si, amorphous silicon thin film single junction, a-Si and copper indium selenide thin film technology CIS) were selected for a series of experimental tests in order to demonstrate the validity of the proposed characterization method. As result, it has been developed and generated the ICD Integral Characterization Diagram, a graphic and visual system to represent the results and manage information, a useful operational tool for decision-making regarding to photovoltaic installations. This diagram shows all concepts and parameters studied in relation to each other and visually provides access to all the results obtained during the experimental phase to make available all the qualitative and quantitative information on the energy performance of the BIPV components by characterizing them in a comprehensive way.

Hydrodynamic modeling of mineral wool fiber suspensions in a two-dimensional channel flow

A consequence of a loss of coolant accident is the damage of adjacent insulation materials (IM). IM may then be transported to the containment sump strainers where water is drawn into the ECCS (emergency core cooling system). Blockage of the strainers by IM lead to an increased pressure drop acting on the operating ECCS pumps. IM can also penetrate the strainers, enter the reactor coolant system and then accumulate in the reactor pressure vessel. An experimental and theoretical study that concentrates on mineral wool fiber transport in the containment sump and the ECCS is being performed. The study entails fiber generation and the assessment of fiber transport in single and multi-effect experiments. The experiments include measurement of the terminal settling velocity, the strainer pressure drop, fiber sedimentation and resuspension in a channel flow and jet flow in a rectangular tank. An integrated test facility is also operated to assess the compounded effects. Each experimental facility is used to provide data for the validation of equivalent computational fluid dynamic models. The channel flow facility allows the determination of the steady state distribution of the fibers at different flow velocities. The fibers are modeled in the Eulerian-Eulerian reference frame as spherical wetted agglomerates. The fiber agglomerate size, density, the relative viscosity of the fluid-fiber mixture and the turbulent dispersion of the fibers all affect the steady state accumulation of fibers at the channel base. In the current simulations, two fiber phases are separately considered. The particle size is kept constant while the density is modified, which affects both the terminal velocity and volume fraction. The relative viscosity is only significant at higher concentrations. The numerical model finds that the fibers accumulate at the channel base even at high velocities; therefore, modifications to the drag and turbulent dispersion forces can be made to reduce fiber accumulation.