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  • Numerical and experimental study of a flat plate collector with honeycomb transparent insulation and overheating protection system

     Kessentini, Hamdi
    Defense's date: 2014-02-14
    Universitat Politècnica de Catalunya
    Theses

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    En esta tesis se presenta un captador solar plano (FPC) con aislamiento transparente plástico (TIM ) y un sistema de protección al sobrecalentamiento de bajo coste. Este captador está destinado a suministrar calor en el rango de temperatura de 80 hasta 120°C. Un canal de ventilación es introducido por debajo del absorbedor con una compuerta térmicamente accionada mediante un sistema de resorte de tipo aleación con memoria. Este canal permite proteger el colector en condiciones de estancamiento, preservando al mismo tiempo un buen rendimiento durante el funcionamiento normal. Para este objetivo, un prototipo ha sido construido y probado experimentalmente. En paralelo, diferentes modelos numéricos se han implementado con el objetivo de predecir el comportamiento térmico de este captador. La presente tesis consta de seis capítulos detallados a continuación. En el primer capítulo, se ha realizado una revisión de la literatura con el fin de presentar el estado del arte más actual en el campo de calor solar a temperaturas medias. Esta revisión ha permitido apreciar los últimos hallazgos y desafíos clave relacionados con el tema estudiado y presentar la contribución de este trabajo al conjunto de conocimientos existentes. El segundo capítulo está dedicado a la descripción del dispositivo experimental: descripción técnica del captador, de los diferentes sensores utilizados y los procedimientos de prueba adoptadas. En el tercer capítulo, se ha implementado un modelo numérico de cálculo rápido. Este modelo está basado en la resolución de los diferentes componentes del captador por medio de una plataforma modular orientada a objetos. Pruebas experimentales de interior y exterior se han llevado a cabo y han demostrado la eficacia del sistema de sobrecalentamiento en condiciones de estancamiento. La comparación de los resultados numéricos con experimentos ha demostrado que el código puede reproducir con precisión el funcionamiento térmico del captador. Varias simulaciones paramétricas se han realizado con el fin de optimizar el diseño del captador: se han evalúado 3125 diferentes configuraciones por medio de prototipos virtuales. Los resultados han permitido proponer el diseño más prometedor del FPC con TIM de plástico capaz de trabajar a temperatura de funcionamiento de 100 °C con eficiencia prometedora. En el cuarto capítulo, los elementos más críticos del colector (canal de ventilación y cámara de aire&TIM) han sido sustituidos por objetos CFD en el código modular implementado. En las simulaciones CFD, se ha utilizado Large Eddy Simulation (LES) modelo. Las soluciones numéricas se han validado primero con casos de referencia y a continuación se han verificado los resultados del modelo general del captador por comparación con las pruebas experimentales que han mostrado buena concordancia. Este análisis preliminar ha permitido entender la transferencia de calor y dinámica de fluido a diferentes temperaturas de funcionamiento del colector estudiado.En el quinto capítulo, se ha llevado a cabo un análisis de la transferencia de calor por radiación y conducción en el aislamiento transparente de estructura alveolar. Este analisis ha sido llevada a cobo mediante de la resolución de la ecuación de energía en su forma tridimensional de forma acoplado a la ecuación de transferencia por radiación (RTE). Se ha utilizado el método de volúmenes finitos para la resolución de la RTE. Los resultados numéricos han sido comparados con resultados experimentales de varios TIM dados por diferentes autores en la literatura mostrando acuerdos aceptables. Un estudio paramétrico se ha llevado a cabo para investigar el efecto de la variación de los parámetros ópticos y dimensionales más relevantes del TIM en la transferencia de calor. Finalmente, el último capítulo resume la contribución de esta tesis y presenta las posibles direcciones de investigación futura.

  • Parallelization strategy for the Volume-of-Fluid method on unstructured meshes

     Borrell, Ricard; Jofre Cruanyes, Lluís; Lehmkuhl Barba, Oriol; Castro Gonzalez, Jesus
    International Conference on Parallel Computational Fluid Dynamics
    Presentation of work at congresses

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    The Volume-of-Fluid (VOF) is one of the most widely used methods for interface tracking in the simulation of multi-fluid flows. The interface between different fluids is generated from the volume fraction scalar fields, which account for the ratio of volume of each fluid in each control volume. Then, an advection equation is solved to obtain the new distribution of the fluids after momentum is applied. Since this is a time-consuming process, parallelization techniques play an essential role. In the VOF approaches most of computing cost of the algorithm is concentrated in operations with the cells that form the interface, i.e. the cells in which coexist different fluids. When the interface is not homogeneously distributed throughout the domain, the standard domain decomposition strategy results in an unbalanced partition. A possible strategy to overcome this limitation is to adapt the domain decomposition to the interface distribution, however, this approach presents a number of drawbacks mainly related to the dynamic location of the interface. In this paper a new strategy, based in a load balancing process complementary to the domain decomposition, is presented with the aim to overcome the limitations of standard domain decomposition based approaches.

  • Modelling and experimental validation of the heat accumulator in a Low Trust Cryogenic Propulsion (LTCP) system¿¿e,

     Torras, Santiago; Castro Gonzalez, Jesus; Rigola Serrano, Joaquim; Morales, Sergio; Riccius, Jorg; Leiner, Johannes
    European Conference for Aerospace Sciences
    Presentation's date: 2013-07-02
    Presentation of work at congresses

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    The study of one of the components, the heat accumulator, of Low Thrust Cryogenic Propulsion systems (LTCP), is of scientific interest in the framework of ISP-1 project [1]. This device stores thermal energy from the fuel cell that provides electrical energy to the whole system. This thermal energy is employed for the pressurization of the propellant tanks. A numerical model is being developed [2] in order to predict the thermal behaviour of the heat accumulator and having a tool for its design in the next future. The numerical model is validated with experimental results of ISP-1 partners (DLR) [3], [4].

  • Experimental and numerical investigation of H2O vapor absorption processes in falling film of LiBr aqueous solution in vertical tubes

     García-Rivera, Eduardo; Castro Gonzalez, Jesus; Farnós, Joan; Oliva Llena, Asensio
    World Conference on Experimental Heat Transfer, Fluid Mechanics, and Thermodynamics
    Presentation's date: 2013-07-20
    Presentation of work at congresses

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    The LiBr-H2O absorption systems are used mainly in large cooling capacity applications (industry, large buildings, etc.), therefore require water from cooling towers to reject heat. However, if middle and low capacity are required (commercial and residential systems), absorption machines should be air-cooled in order to become competitive [1-4]. The absorber represents a major critical component in absorption systems and one of the key issues, in it is the combined heat and mass transfer in the absorption process. For this reason the development of mathematical models for the simulation and experimental data for the validation are always useful tools for the design and improvement of falling film vertical absorbers. A testing device has been designed and built for reproducing absorption phenomena in vertical tubes with the primary objective to obtain experimental data in LiBr-H2O vertical absorbers. The versatility of the experiment allows to obtain a wide range of data.

  • Hot run test results of a validation optimized water-ice phase change heat accumulator and comparison to numerical analysis¿X¿¿c

     Riccius, Jorg; Leiner, Johannes; Castro Gonzalez, Jesus; Rigola Serrano, Joaquim
    European Conference for Aerospace Sciences
    Presentation's date: 2013-07-02
    Presentation of work at congresses

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    Phase change heat accumulators are essential devices for the thermal management of multiple ignition, electric pump driven in-space propulsion systems such as the Low Cost Cryogenic Propulsion (LCCP) system [1], [2]. For Low Temperature Accumulators (LTAs), water/ice is of special interest as phase change material because of its high heat capacity and high latent heat. Therefore, an analysis of the phase change behaviour of both, this heat storage material and an heat transfer medium were performed in the framework of the ISP1 project [2], [3]. In the experiments shown in the current paper, gaseous nitrogen at 80°C is injected to the inlet of the heat transfer tube. By passing through the heat transfer tube, it causes the heat storage medium ice to melt and the hot nitrogen is cooled down. The phase change behaviour of the phase change material ice and the heat transfer process from nitrogen to the ice were analysed experimentally in a qualitative and a quantitative way. Finally, the obtained experimental results are compared to the analysis results of theoretical phase-change models carried out by the ISP-1 partner institution UPC [7], [8], [9].

  • Numerical simulation of wind flow around a parabolic trough solar collector

     Amine Hachicha, Ahmed; Rodriguez Pérez, Ivette Maria; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    Applied energy
    Date of publication: 2013-07-01
    Journal article

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    The use of parabolic trough solar technology in solar power plants has been increased in recent years. Such devices are located in open terrain and can be the subject of strong winds. As a result, the stability of these devices to track accurately the sun and the convection heat transfer from the receiver tube could be affected. In this paper, a detailed numerical aerodynamic and heat transfer model based on Large Eddy Simulations (LES) modelling for these equipments is presented. First, the model is verified on a circular cylinder in a cross-flow. The drag forces and the heat transfer coefficients are then validated with available experimental measurements. After that, simulations are performed on an Eurotrough solar collector to study the fluid flow and heat transfer around the solar collector and its receiver. Computations are carried out for a Reynolds number of ReW = 3.6 × 105 (based on the aperture) and for various pitch angles (¿ = 0°, 45°, 90°, 135°, 180°, 270°). The aerodynamic coefficients are calculated around the solar collector and validated with measurements performed in wind tunnel tests. Instantaneous velocity field is also studied and compared to aerodynamic coefficients for different pitch angles. The time-averaged flow is characterised by the formation of several recirculation regions around the solar collector and the receiver tube depending on the pitch angle. The study also presents a comparative study of the heat transfer coefficients around the heat collector element with the circular cylinder in a cross-flow and the effect of the pitch angle on the Nusselt number.

    The use of parabolic trough solar technology in solar power plants has been increased in recent years. Such devices are located in open terrain and can be the subject of strong winds. As a result, the stability of these devices to track accurately the sun and the convection heat transfer from the receiver tube could be affected. In this paper, a detailed numerical aerodynamic and heat transfer model based on Large Eddy Simulations (LES) modelling for these equipments is presented. First, the model is verified on a circular cylinder in a cross-flow. The drag forces and the heat transfer coefficients are then validated with available experimental measurements. After that, simulations are performed on an Eurotrough solar collector to study the fluid flow and heat transfer around the solar collector and its receiver. Computations are carried out for a Reynolds number of Re W = 3.6 x 10(5) (based on the aperture) and for various pitch angles (h=0,45,90, 135, 80, 270). The aerodynamic coefficients are calculated around the solar collector and validated with measurements performed in wind tunnel tests. Instantaneous velocity field is also studied and compared to aerodynamic coefficients for different pitch angles. The time-averaged flow is characterised by the formation of several recirculation regions around the solar collector and the receiver tube depending on the pitch angle. The study also presents a comparative study of the heat transfer coefficients around the heat collector element with the circular cylinder in a cross-flow and the effect of the pitch angle on the Nusselt number.

  • Solid-liquid phase change with turbulent flow

     Galione Klot, Pedro Andres; Rigola Serrano, Joaquim; Castro Gonzalez, Jesus; Rodriguez Pérez, Ivette Maria
    International Symposium on Turbulence, Heat and Mass Transfer
    Presentation's date: 2012-09-26
    Presentation of work at congresses

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    The present paper describes a numerical simulation of the solid-liquid phase change Computational Fluid Dynamics and Heat Transfer (CFD&HT) model developed in order to account for natural convection inside Phase Change Materials (PCMs) taking into account turbulent effects.

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    Numerical simulation of heat transfer and fluid flow in a flat plate solar collector with TIM and ventilation channel  Open access

     Kessentini, Hamdi; Lehmkuhl Barba, Oriol; Capdevila Paramio, Roser; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    ISES Europe Solar Conference
    Presentation's date: 2012-09-20
    Presentation of work at congresses

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    Flat plate solar collector with plastic transparent insulation materials and ventilation channel as overheating protection system inserted between the absorber and the back insulation has been studied numerically. First, a general object-oriented unsteady model of this solar collector is developed and presented. It allows solving, in parallel way, every component separately and interacting with its neighbors to set the boundary conditions in every time step of the simulation. Every component can be simulated using its own mesh and the number of CPUs necessary (depending on the simulation level needed). Second, the numerical simulations of the fluid flow and heat transfer by natural convection in the bottom part (ventilation channel) and the upper part (air gap + TIM) of the collector are done separately. The simulation has taken into account the different operation modes of the channel (opened at high operation temperatures and closed in normal operations). A three dimensional parallel turbulent CFD model based on Large Eddy Simulation is used in the simulations. The obtained numerical results are validated with experimental and benchmark results found in the literature.

  • Three dimensional numerical simulations of combined conduction and radiation in transparent insulation material

     Kessentini, Hamdi; Capdevila Paramio, Roser; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    ISES Europe Solar Conference
    Presentation's date: 2012-09-19
    Presentation of work at congresses

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  • Numerical simulation of incompressible two phase flows by conservative level set method

     Balcazar Arciniega, Nestor Vinicio; Jofre Cruanyes, Lluís; Lehmkuhl Barba, Oriol; Rigola Serrano, Joaquim; Castro Gonzalez, Jesus
    Conference on Modelling Fluid Flow
    Presentation's date: 2012-09-04
    Presentation of work at congresses

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  • Numerical modelling of the phase change material heat accumulator under fast transient gasification conditions in a low thrust cryogenic propulsion (LTCP) system

     Castro Gonzalez, Jesus; Galione Klot, Pedro Andres; Morales Ruíz, Juan José; Lehmkuhl Barba, Oriol; Rigola Serrano, Joaquim; Perez Segarra, Carlos David; Oliva Llena, Asensio
    International Conference on Space Propulsion
    Presentation's date: 2012-05-09
    Presentation of work at congresses

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  • Modelling of absorption of H2O vapor in falling film of lbr aqueous solution in vertical tubes with presence of non-condensables

     García-Rivera, Eduardo; Castro Gonzalez, Jesus; Farnos Baulenas, Joan; Oliva Llena, Asensio
    IIR-Gustav Lorentzen Conference on Natural Working Fluids
    Presentation's date: 2012-06-26
    Presentation of work at congresses

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    One of the main reasons of the discrepancies between theoretical predictions made by models of absorbers of H2O-LiBr absorption chillers when they are compared with experimental results under real conditions is the presence of non-condensables gases. These non-condensables gases are inside the shell of the absorption chiller mainly for two reasons: i) air leakages (Oxygen-Nitrogen); ii) gases produced by corrosion (Hydrogen). A mathematical model of falling film absorption of H2O by LiBr aqueous solutions which considers the influence of non-condensable gases has been implemented. The model is semi-empirical, based on Navier Stokes equations together with energy and mass species simplified under the boundary layer hypotheses. Under such conditions, the differential system of equations in partial derivatives, becomes parabolic and could be solved by means of finite difference method in a step by step procedure. Detailed heat and mass transfer balances are applied at the interface to specify the boundary conditions between liquid and gas phases. In order to calculate gradient of air at the interface, the penetration theory is applied in order to avoid a detailed calculation of the gas phase. Numerically the presence of air in the interface results in a pressure drop and consequently in a reduction in heat and mass transfer rates.

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    Numerical study of the incompressible Richtmyer-Meshkov instability. Interface tracking methods on general meshes  Open access

     Balcazar Arciniega, Nestor Vinicio; Jofre Cruanyes, Lluís; Lehmkuhl Barba, Oriol; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    Conference on Modelling Fluid Flow
    Presentation's date: 2012-09-04
    Presentation of work at congresses

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    The numerical simulation of interfacial and free surface flows is a vast and interesting topic in the areas of engineering and fundamental physics, such as the study of liquid-gas interfaces, formation of droplets, bubbles and sprays, combustion problems with liquid and gas reagents, study of wave motion and others. Many different methods for interface tracking exist, but Volume-of-Fluid and Level-Set methods are two of the most important. The Volume-of-Fluid preserves mass in a natural way but requires large computational resources. On the other hand, the Level-Set is not as accurate and mass conservative as the Volume-of-Fluid but is a faster way to track interfaces, representing them by the middle contour of a signed distance function. The objective of this work is to analyze the advantatges and drawbacks of the Volume-of-Fluid and Level-Set methods by solving the incompressible two-liquid Richtmyer-Meshkov instability and to compare the results to experimental data.

  • On the validity of the Oberbeck-Boussinesq approximation in a tall differentially heated cavity with water

     Kizildag, Deniz; Rodriguez Pérez, Ivette Maria; Castro Gonzalez, Jesus
    Progress in computational fluid dynamics
    Date of publication: 2012-07-26
    Journal article

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  • Numerical resolution of turbulent flows on complex geometries.  Open access

     Lehmkuhl Barba, Oriol
    Defense's date: 2012-07-26
    Department of Heat Engines, Universitat Politècnica de Catalunya
    Theses

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    This thesis aims at developing a numerical methodology suitable for the direct numerical simulation (DNS) and large-eddy simulation (LES) of turbulent flows in order to be used in complex flows, currently encountered in industrial application. At the same time, the study of such turbulent flows can be an opportunity for gaining insight into the complex physics associated with them. To accomplish these goals, the mathematical formulation, conservative spatial discretization on unstructured grids and time- integration scheme for solving the Navier-Stokes equations are presented. The spatial discretization proposed preserves the symmetry properties of the continuous differential operator and ensure both, stability and conservation of the global kinetic energy balance on any grid. Furthermore, the time-integration technique proposed is an efficient self-adaptive strategy, based on a one-parameter second-order-explicit scheme, which has been successfully tested on both Cartesian staggered and unstructured collocated codes, leading to CPU cost reductions of up to 2.9 and 4.3, respectively. After presenting the general methodology for computing flows in complex geometries with unstructured grids, different LES models and regularization models suitable for these kind of meshes are presented and assessed by means of the analysis of different flows. First, regularization models are tested by means of the simulation of different cases with different level of complexity of the mesh. From a structured grid to a very complex mesh, with zones composed of prism and tetrahedral control volumes. It has been shown, that regularization models are very dependent on the quality of the filtering process. Although good results can be obtained with structured or smooth unstructuredmeshes, their performance is affected under fully irregular unstructured grids. A possible remedy to circumvent this issue is also presented. The main idea is to formulate the C4 model within a LES template. Although preliminary results are promising, further testing is still required. After regularization model assessment, LES models are also tested in a natural convection flow. It is shown that, although first order statistics are well solved for most of the models tested (with the exception of the Smagorinsky model), QR- and dynamic-Smagorinsky models present a better prediction of the second-order statistics. However, if CPU time is considered, then QR model is the best alternative. The second part of the thesis is devoted to the study of turbulent flows past bluff bodies. The cases studied are: the flow past a sphere, the flow past a circular cylinder and the flow past a NACA 0012 airfoil. All these cases shares some characteristics encountered in turbulent flows with massive separations, i.e., flow separation, transition to turbulence in the separated shear-layers and turbulent wakes with periodic shedding of vortices. However there are intrinsic characteristics of the turbulence in each of them, which make them interesting for the studying of the turbulence. Furthermore, the results presented for the flow past a sphere at Re = 3700 and 10000, together with the flow past a NACA 0012 at Re=50000 and AoA = 8 are the first DNS results presented in the literature for both flows. Conclusions drawn from the good results obtained point out that the use of the conservative formulation presented in this thesis, is one of the keys for the success of the SGS models used. This formulation, together with the use of unstructured grids might be a step towards the use of LES models for solving industrial flows on complex geometries at high Reynolds numbers.

    La present tesi proposa una metodologia apte per a realitzar simulacions directes de la turbulència (DNS) i simulacions de les grans escales (LES) de fluxos turbulents en geometries complexes. Tanmateix també s'estudia detalladament els mecanismes bàsics de funcionament dels fluxos turbulents en diferents situacions d'interès industrial i acadèmic. Per acomplir aquest objectiu s'ha desenvolupat una innovadora formulació matemàtica que permet conservar discretament les propietats continues de les equacions governants en malles no estructurades. La formulació proposada preserva la simetries originals dels operadors diferencials, assegurant així l'estabilitat i la conservació de l'energia cinètica turbulent en qualsevol mallat. Posteriorment s'ha proposat una metodologia d'integració temporal basada en una formulació explicita de segon ordre. Aquesta nova tècnica ha demostrat ser entre 2.9 i 4.3 més rapida que les tècniques anteriorment utilitzades per la comunitat. Un cop presentada la formulació per a simular fluxos turbulents en geometries complexes, s'han validat diferents models LES adaptats a malles no estructurades. Els models s'han testejat usant diferents solucions de referencia de la literatura i simulacions d'alt nivell generades en el context de la present tesi. Finalment s'ha conclòs que la conjunció de la formulació bàsica proposada amb alguns del models LES sorgits en els darrers anys es molt efectiva per a simular fluxos turbulents en situacions complexes, essent el Variational Multiscale WALE i el model QR els més adequats per a simular situacions de interes industrial. La segona part de la tesi es dedicada a l'estudi aerodinàmic del flux turbulent al voltant de diferents perfils. El perfils seleccionats son: el flux al voltant d'una esfera, flux al voltant d'un cilindre i flux al voltant d'un perfil NACA 0012. Els tres casos comparteixen fenomenologies com ara separació massiva de capes límits, esteles turbulentes i desprendiment periòdic de remolins. Tot i així cadascun d'ells es comporta diferent a nivell turbulent així que es d'interès estudiar-los i entendre quins son les causes de les diferencies físiques que es troben. Cal recordar que la física estudiada es la que es pot trobar posteriorment en ales d'avió, perfils de turbines de vent, aerodinàmica de cotxes, etc. Finalment recalcar que els resultats DNS del flux al voltant de l'esfera a Re=3700 i Re=10000 conjuntament amb els DNS del flux al voltant del perfil NACA a Re=50000 i AoA =8 son els primers presentats en la literatura internacional en el seu àmbit. Finalment es pot concloure que la formulació conservativa presentada en la tesis juntament amb els diferents models LES d'última generació testejats en la tesis, han demostrat ser una eina eficaç tan per a resoldre fluxos turbulents d'interès acadèmic com per simular situacions d'interès industrial.

  • Performance indicators for the dynamics modeling and control of PEMFC systems  Open access

     Husar, Attila Peter
    Defense's date: 2012-03-07
    Department of Heat Engines, Universitat Politècnica de Catalunya
    Theses

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    Society is gradually becoming aware that the current energy industry, based on the use of fossil fuels, is inefficient, highly polluting and has a finite supply. Within the scientific community, there are indications that hydrogen (H2) as an energy vector, obtained from renewable energy sources, can represent a viable option to mitigate the problems associated with hydrocarbon combustion. In this context, the change from the current energy industry to a new structure with a significant involvement of H2 facilitates the introduction of fuel cells as elements of energy conversion. Polymer Electrolyte Membrane Fuel Cells (PEMFC) are gaining increased attention as viable energy conversion devices for a wide range of applications from automotive, stationary to portable. In order to optimize performance, these systems require active control and thus in-depth knowledge of the system dynamics which include fluid mechanics, thermal dynamics and reaction kinetics. One of the main issues, with respect to proper control of these systems, is the understanding of the water transport mechanisms through the membrane and the liquid water distribution. The thesis is based on the publication of nine international journal articles that are divided into 4 sub-topics: Dynamic fuel cell modeling, fuel cell system control-oriented analysis, identification of parameters and performance indicators and finally, fault and failure detection and system diagnosis. In the sub-topic of Dynamic Fuel cell modeling, experimentally validated Computational Fluid Dynamics (CFD) modeling is used to relate the effects of the physical phenomena associated with fluid mechanics and thermal dynamics, that occur inside the fuel cell [Alonso, 2009][Strahl, 2011], to water distribution. However, since these CFD models cannot be directly used for control, control-oriented models [Kunusch, 2008][Kunusch, 2011] have been developed in parallel. As well, another study is done in [Serra, 2006] which includes a controllability analysis of the system for future development and application of efficient controllers. The results of the above mentioned studies are limited because either they do not incorporate an electrochemical model or the model is not experimentally validated. Moreover, these models do not take into account the voltage losses due to liquid water inside the fuel cell. Therefore, there is a need to properly relate the relevant effects of fluid mechanics and thermal dynamics, including liquid water, to the fuel cell voltage. Primarily, methodologies are needed to determine the relevant indicators associated to the effect of water on the fuel cell performance. The works published in [Husar, 2008] and [Husar, 2011] treats experimental parameter identification, mainly focused on water transport through the membrane and fuel cell voltage loss indicators respectively. The implementation of the indicators indirect measurement methodology provides an experimental way for the isolation of three main types of voltage losses in the fuel cell: activation, mass transport and ohmic losses. Additionally since these voltage loss indicators relate the fuel cell operating conditions to the fuel cell voltage, they can be utilized to calibrate and validate CFD models as well as employed in novel control strategies. On the other hand, to develop reliable systems, the controller should not only take into account performance variables during standard operation but should also be able to detect failures and take the appropriate actions. A preliminary study on failure indicators is presented in [Husar 2007] and fault detection methodologies are described in [de Lira 2011]. As a whole, the compilation of articles represented in this thesis applies a comprehensive experimental approach which describes the implementation of novel methodologies and experimental procedures to characterize and model the PEMFC and their associated systems taking into consideration control oriented goals.

    La societat s'està adonant que la indústria energètica actual, basada en l'ús de combustibles fòssils, és ineficient, molt contaminant i té un subministrament limitat. Dins de la comunitat científica, hi ha indicis que el hidrogen (H2) com vector energètic, obtingut a partir de fonts d'energia renovables, pot representar una opció viable per a mitigar els problemes associats amb la combustió d'hidrocarburs. En aquest context, el canvi de la indústria energètica actual a una nova estructura amb una important participació de el hidrogen exigeix la introducció de les piles de combustible com elements de conversió d'energia. Les piles de combustible de membrana polimèrica (PEMFC) estan tenint cada vegada més atenció com a dispositius viables de conversió d'energia per a una àmplia gamma d'aplicacions com automoció, estacionàries o portàtils. Amb la finalitat d'optimitzar el seu rendiment, les piles PEM requereixen un control actiu i per tant un coneixement profund de la dinàmica del sistema, que inclou la mecànica de fluids, la dinàmica tèrmica i la cinètica de les reaccions. Un dels temes principals relacionat amb el control adequat d'aquests sistemes és la comprensió dels mecanismes de transport d'aigua a través de la membrana i la distribució d'aigua líquida. Aquesta tesi es basa en nou articles publicats en revistes internacionals que es divideixen en 4 subtemes: la modelització dinàmica de piles de combustible, l'anàlisi orientada al control del sistema, la identificació de paràmetres i d’indicadors de funcionament i, finalment, la detecció de fallades i la diagnosi dels sistemes. En el sub-tema de la modelització dinàmica de piles PEM, la modelització basada en la Dinàmica de Fluids Computacional (CFD) amb validació experimental s'ha utilitzat per a relacionar els efectes dels fenòmens físics de la mecànica de fluids i de la dinàmica tèrmica que es produeixen dintre de la pila [Alonso, 2009] [ Strahl, 2011] amb la distribució d'aigua. No obstant això, com aquests models CFD no poden ser utilitzats directament per al control, s'han desenvolupat models orientats a control [Kunusch, 2008] [Kunusch, 2011] en paral·lel. A més, en un altre estudi [Serra, 2006] s'inclou una anàlisi de control·labilitat del sistema per al desenvolupament i aplicació futurs de controladors eficaços. Però els resultats dels estudis esmentats anteriorment són limitats, ja sigui perquè no incorporen un model electroquímic o bé perquè no han estat validats experimentalment. A més, cap dels models té en compte les pèrdues de tensió degudes a l'aigua líquida dins de la pila de combustible. Per tant, hi ha una necessitat de relacionar adequadament els efectes rellevants de la mecànica de fluids i de la dinàmica tèrmica, incloent l'aigua líquida, amb el voltatge de la pila de combustible. Principalment, són necessàries metodologies per a determinar els indicadors rellevants associats a aquest efecte de l'aigua sobre el rendiment de la pila de combustible. Els treballs publicats en [Husar, 2008] i [Husar, 2011] tracten la identificació experimental de paràmetres, centrada en el transport d'aigua a través de la membrana i els indicadors de pèrdua de tensió, respectivament. L'aplicació d'una proposta de metodologia de mesura indirecte dels indicadors permet l'aïllament dels tres tipus principals de pèrdues de voltatge en la pila de combustible: l'activació, el transport de massa i les pèrdues ohmiques. Aquests indicadors de pèrdua de tensió relacionen les condicions d'operació amb el voltatge de la pila de combustible i per tant poden ser utilitzats per a calibrar i validar models CFD, així com per a definir noves estratègies de control. D'altra banda, per a aconseguir sistemes fiables, el controlador no només ha de considerar els indicadors de funcionament de l'operació normal, sinó que també ha de detectar possibles fallades per a poder prendre les accions adequades en cas de fallada. Un estudi preliminar sobre indicadors de fallades es presenta en [Husar 2007] i una metodologia de detecció de fallades completa es descriu en [Lira de 2011]. En el seu conjunt, el compendi d'articles que formen aquesta tesi segueix un enfocament experimental i descriu la implementació de noves metodologies i procediments experimentals per a la caracterització i el modelatge de piles PEM i els sistemes associats amb objectius orientats al control eficient d'aquests sistemes.

    La sociedad se ésta dando cuenta de que la industria energética actual, basada en el uso de combustibles fósiles, es ineficiente, muy contaminante y tiene un suministro limitado. Dentro de la comunidad científica, hay indicios de que el hidrógeno (H2) como vector energético, obtenido a partir de fuentes de energía renovables, puede representar una opción viable para mitigar los problemas asociados con la combustión de hidrocarburos. En este contexto, el cambio de la industria energética actual a una nueva estructura con una importante participación de H2 exige la introducción de pilas de combustible como elementos de conversión de energía. Las pilas de combustible de membrana polimérica (PEMFC) están ganando cada vez más atención como dispositivos viables de conversión de energía para una amplia gama de aplicaciones como automoción, estacionarias o portátiles. Con el fin de optimizar su rendimiento, las pilas PEM requieren un control activo y por lo tanto un conocimiento profundo de la dinámica del sistema, que incluye la mecánica de fluidos, la dinámica térmica y la cinética de las reacciones. Uno de los temas principales relacionado con el control adecuado de estos sistemas, es la comprensión de los mecanismos de transporte de agua a través de la membrana y la distribución de agua líquida. Esta tesis se basa en la publicación de nueve artículos en revistas internacionales que se dividen en 4 sub-temas: el modelado dinámico de pilas de combustible, el análisis orientado a control del sistema, la identificación de parámetros e indicadores de desempeño y, por último, la detección de fallos y la diagnosis. En el sub-tema de la modelización dinámica de pilas PEM, el modelado basado en Dinámica de Fluidos Computacional (CFD) con validación experimental se ha utilizado para relacionar los efectos de los fenómenos físicos de la mecánica de fluidos y la dinámica térmica que se producen dentro de la pila [Alonso, 2009] [ Strahl, 2011] con la distribución de agua. Sin embargo, como estos modelos CFD no pueden ser utilizados directamente para el control, modelos orientados a control [Kunusch, 2008] [Kunusch, 2011] se han desarrollado en paralelo. Además, en otro estudio [Serra, 2006] se incluye un análisis de controlabilidad del sistema para el futuro desarrollo y aplicación de controladores eficaces. Pero los resultados de los estudios mencionados anteriormente son limitados, ya sea porque no incorporan un modelo electroquímico o bien porque no son validados experimentalmente. Además, ninguno de los modelos tiene en cuenta las pérdidas de tensión debidas al agua líquida dentro de la pila de combustible. Por lo tanto, hay una necesidad de relacionar adecuadamente los efectos relevantes de la mecánica de fluidos y la dinámica térmica, incluyendo el agua líquida, con la tensión de la pila de combustible. Principalmente, son necesarias metodologías para determinar los indicadores relevantes asociados al efecto del agua sobre el rendimiento de la pila de combustible. Los trabajos publicados en [Husar, 2008] y [Husar, 2011] tratan la identificación experimental de parámetros, centrada en el transporte de agua a través de la membrana y los indicadores de pérdida de tensió, respectivamente. La aplicación de una metodología propuesta de medición indirecta de los indicadores permite el aislamiento de los tres tipos principales de pérdidas de tensión en la pila de combustible: la activación, el transporte de masa y las pérdidas óhmicas. Éstos indicadores de pérdida de tensión relacionan las condiciones de operación con la tensión de la pila de combustible y por lo tanto pueden ser utilizados para calibrar y validar modelos CFD, así como para definir nuevas estrategias de control. Por otro lado, para conseguir sistemas fiables, el controlador no sólo debe considerar los indicadores de desempeño de la operación regular, sino que también debe detectar posibles fallos para poder tomar las acciones adecuadas en caso de fallo. Un estudio preliminar sobre indicadores de fallos se presenta en [Husar 2007] y una metodología de detección de fallos completa se describe en [Lira de 2011]. En su conjunto, el compendio de artículos que forman esta tesis sigue un enfoque experimental y describe la implementación de nuevas metodologías y procedimientos experimentales para la caracterización y el modelado de pilas PEM y los sistemas asociados con objetivos orientados al control eficiente de estos sistemas.

  • SIMULACION NUMERICA Y VALIDACION EXPERIMETNAL DE FENOMENOS DE CAMBIO DE FASE LIQUIDO-VAPOR

     Castro Gonzalez, Jesus; Lopez Mas, Joan; Ablanque Mejia, Nicolas; Oliet Casasayas, Carles; Rigola Serrano, Joaquim
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  • Captador solar con aislamiento transparente plástico y protección al sobrecalentamiento

     Castro Gonzalez, Jesus; Oliva Llena, Asensio; Rodriguez Pérez, Ivette Maria
    Date of request: 2012-03-02
    Invention patent

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    Captador solar con aislamiento transparente plástico y protección al sobrecalentamiento.

    La presente invención tiene como finalidad perfeccionar la mejora de captadores solares térmicos planos o de baja concentración con aislamiento térmico transparente en la cubierta, aumentando su rendimiento, minimizando los costes de producción y el peso de éstos.

    Más concretamente, se refiere al uso de sistemas de protección al sobrecalentamiento de los materiales transparentes aislantes plásticos en estructura alveolar mediante canal de ventilación.

    También se plantea el concepto de captador integrado con cubierta con aislamiento transparente plástico en estructura alveolar, en el que existe un depósito de un fluido que actúa de acumulador de energía térmica, integrado en el captador, que a la vez dota de inercia térmica a todo el sistema, limitando la temperatura máxima alcanzada en el mismo. El depósito acumulador incorpora una válvula limitadora de presión y temperatura, aprovechando el calor latente de cambio de fase líquido/vapor.

  • Numerical resolution in a PCM accumulator in cryogenic conditions

     Morales Ruiz, Sergio; Rigola Serrano, Joaquim; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    IIR International Congress of Refrigeration
    Presentation's date: 2011-08-21
    Presentation of work at congresses

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  • VOF/Navier-Stokes implementation on 3D unstructured staggered meshes. Application to the Richtmyer-Meshkov instability

     Jofre Cruanyes, Lluís; Lehmkuhl Barba, Oriol; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    International Conference on Computational Heat and Mass Transfer
    Presentation's date: 2011-07-18
    Presentation of work at congresses

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    The numerical simulation of interfacial and free surface flows is a vast and interesting topic in the areas of engineering and fundamental physics, such as the study of liquid-gas interfaces, formation of droplets, bubbles and sprays, combustion problems with liquid and gas reagents, study of wave motion and others. One of the most powerful and robust methods for interface tracking on fixed grids is the Volume-of-Fluid (VOF). This method tracks the interface between different fluids by evolving the volume fraction scalar field, ratio of fluid to total volume, in time. First, the interface geometry is reconstructed from local volume fraction data. Then, the interface reconstruction and the solution of the Navier-Stokes equations are used to solve the volume fraction advection equation. The objective of this work is to implement a fast, accurate and parallelizable VOF/Navier-Stokes model well suited to 3D unstructured staggered meshes. The interface will be reconstructed by a PLIC method and the advection step will be computed by the means of an unsplit-advection volume tracking algorithm. On the other hand, the Navier- Stokes equations will be solved using an unstructured staggered formulation. The VOF/Navier-Stokes implementation will be tested by comparing the solution of the Richtmyer-Meshkov instability (RMI) to experimental results. The Richtmyer-Meshkov instability occurs at a nearly planar interface separating two fluids that are impulsively accelerated in the direction normal to the interface. This impulsive acceleration can be the result of an impulsive body force or a passing shock wave.

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    Numerical and experimental study of a flat plate solar collector with transparent insulation and overheating protection system  Open access

     Kessentini, Hamdi; Capdevila Paramio, Roser; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    ISES Solar World Congress
    Presentation's date: 2011-08-28
    Presentation of work at congresses

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    In this paper a FPSC with TIM and an overheating protection system is investigated numerically and experimentally. The studied collector has been manufactured using a process similar to that of the conventional FPSC but by inserting a honeycomb TIM glued under the glass cover. The designed overheating protection system consists of a ventilation channel inserted between the absorber and the back insulation and has a thermally actuated door which opens when it reaches a specific temperature and remains closed otherwise. This system is designed to protect the collector when reaching stagnation conditions while preserving good performances during normal operations.

  • Numerical resolution of the heat accumulator in a Low Cost Cryogenic Propulsion (LCCP) system

     Morales Ruiz, Sergio; Castro Gonzalez, Jesus; Rigola Serrano, Joaquim; Perez Segarra, Carlos David; Oliva Llena, Asensio
    European Conference for Aerospace Sciences
    Presentation's date: 2011-07-08
    Presentation of work at congresses

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  • Simulaton of absorption of H2O in falling film of LiBr aqueous in vertical tubes in wavy regime

     García-Rivera, Eduardo; Castro Gonzalez, Jesus; Farnos Baulenas, Joan; Oliva Llena, Asensio
    International Sorption Heat Pump Conference
    Presentation's date: 2011-04-06
    Presentation of work at congresses

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    Parallelization study of a VOF/Navier-Stokes model for 3D unstructured staggered meshes  Open access

     Jofre Cruanyes, Lluís; Lehmkuhl Barba, Oriol; Borrell Pol, Ricard; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    International Conference on Parallel Computational Fluid Dynamics
    Presentation's date: 2011-05-16
    Presentation of work at congresses

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    The numerical simulation of interfacial and free surface flows is a vast and interesting topic in the areas of engineering and fundamental physics, such as the study of liquid-gas interfaces, formation of droplets, bubbles and sprays, combustion problems with liquid and gas reagents, study of wave motion and others. One of the most powerful and robust methods for interface tracking on fixed grids is the Volume-of-Fluid (VOF). This method tracks the interface between different fluids by evolving the volume fraction scalar field, ratio of fluid to total volume, in time. First, the interface geometry is reconstructed from local volume fraction data. Then, the interface reconstruction and the solution of the Navier-Stokes equations are used to compute the volume fraction advection equation. The objective of this work is to implement a fast, accurate and efficiently parallelizated VOF/Navier-Stokes model well suited to 3D unstructured staggered meshes. The interface will be reconstructed by a PLIC method and the advection step will be computed by the means of an unsplit-advection volume tracking algorithm. On the other hand, the Navier-Stokes equations will be solved using an unstructured staggered formulation. The parallelization of the VOF/Navier-Stokes model will be studied by solving the Richtmyer-Meshkov instability (RMI). The Richtmyer-Meshkov instability occurs at a nearly planar interface separating two fluids that are impulsively accelerated in the direction normal to the interface. This impulsive acceleration can be the result of an impulsive body force or a passing shock wave.

    Postprint (author’s final draft)

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    Experimental evaluation of a pre-industrial air-cooled LiBr-H2O small capacity absorption machine  Open access

     Chiva Segura, Jorge; Farnos Baulenas, Joan; Castro Gonzalez, Jesus; García-Rivera, Eduardo; Oliva Llena, Asensio
    ISES Solar World Congress
    Presentation's date: 2011-08-28
    Presentation of work at congresses

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    The paper studies thermal design and describes the experimental set-up of a domestic-scale prototype experimental cooling system based on a 7kW of nominal capacity single-stage small LiBr-H2O air-cooled absorption machine. The paper illustrates the characteristics based on a methodical procedure for the design and sizing of the small capacity air-cooled absorption machine.

  • Detailed analysis of turbulent flows in air curtains

     Jaramillo Ibarra, Julian Ernesto; Perez Segarra, Carlos David; Lehmkuhl Barba, Oriol; Castro Gonzalez, Jesus
    Progress in computational fluid dynamics
    Date of publication: 2011
    Journal article

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  • Q-00011

     Rigola Serrano, Joaquim; Rodriguez Pérez, Ivette Maria; Castro Gonzalez, Jesus; Torrades Carné, Francesc; Oliva Llena, Asensio
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  • Q-00006

     Rigola Serrano, Joaquim; Oliet Casasayas, Carles; Calventus Sole, Yolanda; Puig Montada, Ana M.; Castro Gonzalez, Jesus
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  • Q-00025

     Perez Segarra, Carlos David; Rigola Serrano, Joaquim; Castro Gonzalez, Jesus; Oliet Casasayas, Carles; Rodriguez Pérez, Ivette Maria; Lehmkuhl Barba, Oriol; Oliva Llena, Asensio
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  • Q-00005

     Oliva Llena, Asensio; Perez Segarra, Carlos David; Castro Gonzalez, Jesus; Rodriguez Pérez, Ivette Maria; Oliet Casasayas, Carles; Lehmkuhl Barba, Oriol; Soria Guerrero, Manel; Torrades Carné, Francesc; Codina Macià, Esteban; Khamashta Shahin, Munir; Rigola Serrano, Joaquim
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  • Object-oriented simulation of reciprocating compressors: numerical verification and experimental comparison

     Mohan Damle, Rashmin; Rigola Serrano, Joaquim; Perez Segarra, Carlos David; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    International journal of refrigeration / Revue internationale du froid
    Date of publication: 2011-12-01
    Journal article

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    Numerical simulation of reciprocating compressors is important for the design, development, improvement and optimization of the elements constituting the compressor circuit. In this work, an object-oriented unstructured modular numerical simulation of reciprocating compressors is presented. Pressure correction approach is applied for the resolution of tubes, chambers and compression chambers, while valve dynamics are modelled assuming a spring-mass system having single degree of freedom. The modular approach offers advantages of handling complex circuitry (e.g. parallel paths, multiple compressor chambers, etc.), coupling different simulation models for each element and adaptability to different configurations without changing the program. The code has been verified with some basic tests for assuring asymptotic behaviour to guarantee error free code and physically realistic results. Cases with different compressor configurations and working fluids (R134a, R600a and R744) have also been worked out. Numerical results are compared with experimental data and illustrative cases of multi-stage compression are also presented.

  • A PLIC-VOF implementation on parallel 3D unstructured meshes

     Jofre Cruanyes, Lluís; Lehmkuhl Barba, Oriol; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    European Conference on Computational Fluid Dynamics
    Presentation's date: 2010-06-14
    Presentation of work at congresses

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    The numerical simulation of interfacial and free surface ows is a vast and interesting topic in the areas of engineering and fundamental physics, such as the study of liquid-gas interfaces, formation of droplets, bubbles and sprays, combustion problems with liquid and gas reagents, study of wave motion and others. One of the most powerful and robust methods for interface simulation in xed grids is the Volume-of-Fluid (VOF). In this method, the fluids are represented by a scalar fi eld Ck, known as volume fraction, that represents the portion of volume lled with fluid k. Given a velocity fi eld, interfaces are then tracked by evolving fluid volumes in time. At any time in the solution, an exact interface location is not known. Interface geometry is instead inferred (based on assumptions of the particular algorithm) and its location is reconstructed from local volume fraction data (Interface Reconstruction). The reconstructed interface is then used to compute the volume fluxes necessary for the convective terms in the volume evolution equation (Advection). The objective of this work is to implement a fast, accurate and parallelizable VOF method well suited to 3D unstructured meshes. The selected interface reconstruction algorithms will be the Youngs' (fi rst order) and the LVIRA (second order). In the other hand, the advection step will be computed by the means of an unsplit-advection volume tracking algorithm. In the paper, the VOF method will be tested for different test problems. First, a study of reconstruction accuracy, it is most easily assessed by analyzing the reconstruction of known geometries, such as a hollowed sphere. Second, a rotation test, where a velocity field is imposed and the advection algorithm is tested.

  • New implementations of surface tension forces for PLIC-VOF methods

     Castro Gonzalez, Jesus; Oliva Llena, Asensio
    International Heat Transfer Conference
    Presentation's date: 2010-08-10
    Presentation of work at congresses

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    A comparative study has been carried out between different models of implementing surface tension for PLIC-VOF methods: i) the well known Continuum Surface Force (CSF); ii) Staggered Grid Interface Pressure (SGIP); iii) Modified Meier's. As main difference with respect the CSF model, the two last use information of the interface location for the calculation of the surface tension forces, therefore, they need a model of interface reconstruction. The models will be tested under static and dynamic conditions, for the case of a drop and bubble between water and air. In order to reduce the "parasitic" currents that is characteristic of this type of models, two different strategies are used; i) a new method for the calculation of the interface curvature based on the use of polar coordinates; ii) the use of kernels for smoothing the jump of the colour function and the interface. Additionally, the influence of the order of accurancy of the reconstruction algorithms employed that effect the curvature estimation and the surface tension force calculation is also checked. After testing the different cases, it can be concluded that SGIP and modified Meier perform in a comparable way, and much better than CSF model without kernel, that is only competitive with the use of the kernels. However, modified Meier is preferred resptec SGIP due to its straigth forward implementation on unstructured meshes.

  • Modelling of fin-and-tube evaporators considering non-uniform in-tube heat transfer

     Oliet Casasayas, Carles; Perez Segarra, Carlos David; Castro Gonzalez, Jesus; Oliva Llena, Asensio
    International journal of thermal sciences
    Date of publication: 2010-04
    Journal article

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  • Sistemas de refrigeració doméstica modulares y de alta energética

     Oliet Casasayas, Carles; Castro Gonzalez, Jesus; Lehmkuhl Barba, Oriol; Perez Segarra, Carlos David; Oliva Llena, Asensio; Rigola Serrano, Joaquim
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  • Unsteady numerical simulation of the cooling process of vertical storage tanks under laminar natural convection

     Rodriguez Pérez, Ivette Maria; Castro Gonzalez, Jesus; Perez Segarra, Carlos David; Oliva Llena, Asensio
    International journal of thermal sciences
    Date of publication: 2009-04
    Journal article

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    Comparison of the performance of falling film and bubble absorbers for air-cooled absorption systems  Open access

     Castro Gonzalez, Jesus; Oliet Casasayas, Carles; Rodriguez Pérez, Ivette Maria; Oliva Llena, Asensio
    International journal of thermal sciences
    Date of publication: 2009-07-01
    Journal article

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    Small capacity, air-cooled NH3–H2O absorption systems are becoming more attractive in applications where the input energy can be obtained for free (e.g., solar energy, exhaust gases of engines, etc.), due to the increasing price of the primary energy. One of the main difficulties for a wider use of absorption machines is the necessary high initial investment. For this reason, the development of air-cooled systems could be an important achievement for low capacity applications. In this work, two types of air-cooled absorber have been modelled: (i) falling film flow; (ii) bubble flow. The two models have been validated with experimental data obtained from a developed testing device and published numerical results of other authors from another model. The agreement is acceptable for both cases. Finally, a parametric study has been done for air-conditioning and refrigeration in a mobile application taking advantage of the exhaust gases of the engine. In both cases, the performance of the bubble absorber has been higher.

    The original publication is available at: doi:10.1016/j.ijthermalsci.2009.01.003

    Postprint (author’s final draft)

  • SIMULACION NUMERICA Y VALIDACION EXPERIMENTAL DE FENOMENOS DE CAMBIO DE FASE DE LIQUIDO-VAPOR. APLICACION A SISTEMAS Y EQUIPOS TERMI

     Castro Gonzalez, Jesus; Oliet Casasayas, Carles; Ablanque Mejia, Nicolas; Lopez Mas, Joan; Rigola Serrano, Joaquim
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  • CENTRE TECNOLOGIC TRANSFERENCIA CALOR

     Rigola Serrano, Joaquim; Castro Gonzalez, Jesus; Rodriguez Pérez, Ivette Maria; Oliet Casasayas, Carles; Borrell Pol, Ricard; Carmona Muñoz, Angel; Torras Ortiz, Santiago; Mohan Damle, Rashmin; Lopez Mas, Joan; Kizildag, Deniz; Ablanque Mejia, Nicolas; Lehmkuhl Barba, Oriol; Soria Guerrero, Manel; Gorobets, Andrey; Capdevila Paramio, Roser; Jaramillo Ibarra, Julian Ernesto; Morales Ruiz, Sergio; Trias Miquel, Francesc Xavier; Perez Segarra, Carlos David; Sadurni Caballol, Alexandre; Oliva Llena, Asensio
    Participation in a competitive project

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  • MAQUINA D'OBSERVACIO SOLAR REFREDADA PER AIRE

     Oliva Llena, Asensio; Garcia Rivera, Eduardo; Farnos Baulenas, Joan; Castro Gonzalez, Jesus
    Participation in a competitive project

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  • IN SPACE PROPULSION-1

     Jofre Cruanyes, Lluís; Morales Ruiz, Sergio; Oliva Llena, Asensio; Perez Segarra, Carlos David; Castro Gonzalez, Jesus
    Participation in a competitive project

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  • Multidimensional and Unsteady Simulation of Fin-and-Tube Heat Exchangers

     Oliet Casasayas, Carles; Perez Segarra, Carlos David; Oliva Llena, Asensio; Castro Gonzalez, Jesus
    Numerical heat transfer. Part A, applications
    Date of publication: 2009-01
    Journal article

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  • Modelling of the heat exchangers of a small capacity, hot water driven, air-cooled H2O-LiBr absorption cooling machine

     Castro Gonzalez, Jesus; Oliva Llena, Asensio; Perez Segarra, Carlos David; Oliet Casasayas, Carles
    International journal of refrigeration / Revue internationale du froid
    Date of publication: 2008-01
    Journal article

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  • Critical analysis of the available ammonia horizontal in-tube flow boiling heat transfer correlations for liquid overfeed evaporators

     Ablanque Mejia, Nicolas; Rigola Serrano, Joaquim; Oliet Casasayas, Carles; Castro Gonzalez, Jesus
    Journal of heat transfer . Transactions of the ASME
    Date of publication: 2008-03
    Journal article

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  • Recent developments in the design of a new air-cooled, hot-water-driven, H2O-LiBr absorption chiller

     Castro Gonzalez, Jesus; Oliva Llena, Asensio; Perez Segarra, Carlos David; Oliet Casasayas, Carles
    ASHRAE Winter Meeting
    Presentation of work at congresses

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  • Accuracy evaluation of volume tracking methods for free surface flows

     Castro Gonzalez, Jesus
    Fifth European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS)
    Presentation's date: 2008-06-30
    Presentation of work at congresses

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  • Recent developments in the design of a new air-cooled, hot-water-driven, H2O-LiBr absorption chiller

     Castro Gonzalez, Jesus
    ASHRAE Winter Meeting
    Presentation's date: 2008-01-19
    Presentation of work at congresses

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  • DESARROLLO DE SUPERFICIES DE TRANSFERENCIA DE CALOR AVANZADAS EN INTERCAMBIADORES DE CALOR COMPACTOS DE TUBOS Y ALETAS. APLICACIÓN A

     Perez Segarra, Carlos David; Oliet Casasayas, Carles; Castro Gonzalez, Jesus
    Participation in a competitive project

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  • Cálculo de la curva de un colector con doble capa de aislante

     Castro Gonzalez, Jesus; Oliva Llena, Asensio
    Date: 2008-10
    Report

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