Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 50 of 136 results
  • Numerical and experimental study of a flat plate collector with honeycomb transparent insulation and overheating protection system  Open access

     Kessentini, Hamdi
    Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    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.

    In this thesis a flat plate collector (FPC) with plastic transparent insulation materials (TIM) and a low-cost overheating protection system destined for heat supply from 80 to 120°C is presented. A ventilation channel with a thermally actuated door is inserted below the absorber allowing to protect the collector from stagnation conditions, while preserving good performance during normal operation. For this objective, a prototype has been constructed and experimentally tested and in parallel, numerical and CFD models have been implemented with the aim of predicting the thermal behavior of this collector. The present thesis consists of six chapters and a brief summary of each one is given below: In the first chapter, a literature survey is carried out in order to present the most updated R&D status in the field of solar heat at medium temperatures. This literature research has allowed to appreciate the latest findings and key challenges related to the studied topic and to present the contribution of this work to the pool of existing knowledge. The second chapter is devoted to the description of the experimental set up. The problem of overheating for FPC with TIM is first pointed out and the technical description of the studied FPC is then presented. The different sensors used and the test procedures adopted during the experiments are presented. In the third chapter, a fast calculation numerical model is implemented. This model is based on the resolution of the different components of the collector by means of a modular object-oriented platform. Indoor and outdoor tests are performed and have shown the effectiveness of the overheating system being able to maintain low enough temperatures at the collector preventing thus the plastic TIM from stagnation conditions. The comparison of the numerical results with experiments has demonstrated that the code can accurately reproduce the performance of the collector. Several parametric simulations are then performed in order to optimize the collector design: 3125 different configurations are evaluated by means of virtual prototyping and the results have allowed to propose the most promising design of a stagnation proof FPC with plastic TIM able to work at operating temperature 100°C with promising efficiency. In the forth chapter, the most critical elements of the collector (ventilation channel and air gap&TIM) have been substituted by high-level CFD objects in the implemented modular object-oriented code. For the detailed numerical simulations, Large Eddy Simulations (LES) modeling is used. In order to speed-up the simulations, parallelisation techniques are used. The numerical solutions are firstly validated with benchmark cases. Then, the general model of the collector is validated by comparison of the numerical results with the indoor experimental tests showing a reasonable agreement. The preliminary CFD simulation results have allowed to understand the heat transfer and fluid flow at different operating temperatures of the studied collector. In the fifth chapter, a heat transfer analysis of the honeycomb TIM is carried out. The combined radiation and conduction heat transfer across the isolated cell is treated by means of the solution of the energy equation in its three dimensional form which is coupled to the Radiative Transfer Equation (RTE). The Finite Volume Method is used for the resolution of the RTE. The numerical results are compared to experimental measurements of the heat transfer coefficient on various honeycomb TIM given by different authors in the literature showing acceptable agreements. Finally, a parametric study is conducted in order to investigate the effect of the variation of the most relevant optical and dimensional parameters of the TIM on the heat transfer. Finally, the last chapter summarizes the contribution of this thesis and discuss the possible directions of future research.

  • Numerical simulation of multiphase immiscible flow on unstructured meshes  Open access

     Jofre Cruanyes, Lluís
    Department of Heat Engines, Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Aquesta tesi té com a objectiu desenvolupar una base per a la simulació numèrica de fluids multi-fase immiscibles. Aquesta estratègia, encara que limitada per la potència computacional dels computadors actuals, és potencialment molt important, ja que la majoria de la fenomenologia d'aquests fluids sovint passa en escales temporals i especials on les tècniques experimentals no poden ser utilitzades. En particular, aquest treball es centra en desenvolupar discretitzacions numèriques aptes per a malles no-estructurades en tres dimensions (3-D). En detall, el primer capítol delimita els casos multifásics considerats al cas en que els components són fluids immiscibles. En particular, la tesi es centra en aquells casos en que dos o més fluids diferents són separats per interfases, i per tant, corresponentment anomenats fluxos separats. A més a més, un cop el tipus de flux es determinat, el capítol introdueix les característiques físiques i els models disponibles per predir el seu comportament, així com també la formulació matemàtica i les tècniques numèriques desenvolupades en aquesta tesi.El segon capítol introdueix i analitza un nou mètode ¿Volume-of-Fluid¿ (VOF) apte per a capturar interfases en malles Cartesianes i no-estructurades 3-D. El mètode reconstrueix les interfases com aproximacions ¿piecewise planar approximations¿ (PLIC) de primer i segon ordre, i advecciona els volums amb un algoritme geomètric ¿unsplit Lagrangian-Eulerian¿ (LE) basat en construïr els poliedres a partir de les velocitats dels vèrtexs de les celdes. D'aquesta manera, les situacions de sobre-solapament entre poliedres són minimitzades.Complementant el capítol anterior, el tercer proposa una estratègia de paral·lelització pel mètode VOF. L'obstacle principal és que els costos computacionals estan concentrats en les celdes de l'interfase entre fluids. En conseqüència, si la interfase no està ben distribuïda, les estratègies de ¿domain decomposition¿ (DD) resulten en distribucions de càrrega desequilibrades. Per tant, la nova estratègia està basada en un procés de balanceig de càrrega complementària a la DD. La seva eficiència en paral·lel ha sigut analitzada utilitzant fins a 1024 CPU-cores, i els resultats obtinguts mostren uns guanys respecte l'estratègia DD de fins a 12x, depenent del tamany de la interfase i de la distribució inicial.El quart capítol descriu la discretització de les equacions de Navier-Stokes per a una sola fase, per després estendre-ho al cas multi-fase. Una de les característiques més importants dels esquemes de discretització, a part de la precisió, és la seva capacitat per conservar discretament l'energia cinètica, específicament en el cas de fluxos turbulents. Per tant, aquest capítol analitza la precisió i propietats de conservació de dos esquemes de malla diferents: ¿collocated¿ i ¿staggered¿.L'extensió dels esquemes de malla aptes per els casos de una sola fase als casos multi-fase es desenvolupa en el cinquè capítol. En particular, així com en el cas de la simulació de la turbulència les tècniques numèriques han evolucionat per a preservar discretament massa, moment i energia cinètica, els esquemes de malla per a la discretització de fluxos multi-fase han evolucionat per millorar la seva estabilitat i robustesa. Per lo tant, aquest capítol presenta i analitza dos discretitzacions de malla ¿collocated¿ i ¿staggered¿ particulars, aptes per simular fluxos multi-fase, que afavoreixen la conservació discreta de massa, moment i energia cinètica.Finalment, el capítol sis simula numèricament la inestabilitat de Richtmyer-Meshkov (RM) de dos fluids immiscibles i incompressibles. Aquest capítol es una prova general dels mètodes numèrics desenvolupats al llarg de la tesi. En particular, la inestabilitat ha sigut simulada mitjançant un mètode VOF i un esquema de malla ¿staggered¿. Els resultats numèrics corresponents han demostrat la capacitat del sistema discret en obtenir bons resultats per la inestabilitat RM.

    The present thesis aims at developing a basis for the numerical simulation of multiphase flows of immiscible fluids. This approach, although limited by the computational power of the present computers, is potentially very important, since most of the physical phenomena of these flows often happen on space and time scales where experimental techniques are impossible to be utilized in practice. In particular, this research is focused on developing numerical discretizations suitable for three-dimensional (3-D) unstructured meshes. In detail, the first chapter delimits the considered multiphase flows to the case in which the components are immiscible fluids. In particular, the focus is placed on those cases where two or more continuous streams of different fluids are separated by interfaces, and hence, correspondingly named separated flows. Additionally, once the type of flow is determined, the chapter introduces the physical characteristics and the models available to predict its behavior, as well as the mathematical formulation that sustains the numerical techniques developed within this thesis. The second chapter introduces and analyzes a new geometrical Volume-of-Fluid (VOF) method for capturing interfaces on 3-D Cartesian and unstructured meshes. The method reconstructs interfaces as first- and second-order piecewise planar approximations (PLIC), and advects volumes in a single unsplit Lagrangian-Eulerian (LE) geometrical algorithm based on constructing flux polyhedrons by tracing back the Lagrangian trajectories of the cell-vertex velocities. In this way, the situations of overlapping between flux polyhedrons are minimized. Complementing the previous chapter, the third one proposes a parallelization strategy for the VOF method. The main obstacle is that the computing costs are concentrated in the interface between fluids. Consequently, if the interface is not homogeneously distributed, standard domain decomposition (DD) strategies lead to imbalanced workload distributions. Hence, the new strategy is based on a load balancing process complementary to the underlying domain decomposition. Its parallel efficiency has been analyzed using up to 1024 CPU-cores, and the results obtained show a gain with respect to the standard DD strategy up to 12x, depending on the size of the interface and the initial distribution. The fourth chapter describes the discretization of the single-phase Navier-Stokes equations to later extend it to the case of multiphase immiscible flow. One of the most important characteristics of the discretization schemes, aside from accuracy, is their capacity to discretely conserve kinetic energy, specially when solving turbulent flow. Hence, this chapter analyzes the accuracy and conservation properties of two particular collocated and staggered mesh schemes. The extension of the numerical schemes suitable for the single-phase Navier-Stokes equations to the case of multiphase immiscible flow is developed in the fifth chapter. Particularly, while the numerical techniques for the simulation of turbulent flow have evolved to discretely preserve mass, momentum and, specially, kinetic energy, the mesh schemes for the discretization of multiphase immiscible flow have evolved to improve their stability and robustness. Therefore, this chapter presents and analyzes two particular collocated and staggered mesh discretizations, able to simulate multiphase immiscible flow, which favor the discrete conservation of mass, momentum and kinetic energy. Finally, the sixth chapter numerically simulates the Richtmyer-Meshkov (RM) instability of two incompressible immiscible liquids. This chapter is a general assessment of the numerical methods developed along this thesis. In particular, the instability has been simulated by means of a VOF method and a staggered mesh scheme. The corresponding numerical results have shown the capacity of the discrete system to obtain accurate results for the RM instability.

    Aquesta tesi té com a objectiu desenvolupar una base per a la simulació numèrica de fluids multi-fase immiscibles. Aquesta estratègia, encara que limitada per la potència computacional dels computadors actuals, és potencialment molt important, ja que la majoria de la fenomenologia d'aquests fluids sovint passa en escales temporals i especials on les tècniques experimentals no poden ser utilitzades. En particular, aquest treball es centra en desenvolupar discretitzacions numèriques aptes per a malles no-estructurades en tres dimensions (3-D). En detall, el primer capítol delimita els casos multifásics considerats al cas en que els components són fluids immiscibles. En particular, la tesi es centra en aquells casos en que dos o més fluids diferents són separats per interfases, i per tant, corresponentment anomenats fluxos separats. A més a més, un cop el tipus de flux es determinat, el capítol introdueix les característiques físiques i els models disponibles per predir el seu comportament, així com també la formulació matemàtica i les tècniques numèriques desenvolupades en aquesta tesi. El segon capítol introdueix i analitza un nou mètode "Volume-of-Fluid" (VOF) apte per a capturar interfases en malles Cartesianes i no-estructurades 3-D. El mètode reconstrueix les interfases com aproximacions "piecewise planar approximations" (PLIC) de primer i segon ordre, i advecciona els volums amb un algoritme geomètric "unsplit Lagrangian-Eulerian" (LE) basat en construïr els poliedres a partir de les velocitats dels vèrtexs de les celdes. D'aquesta manera, les situacions de sobre-solapament entre poliedres són minimitzades. Complementant el capítol anterior, el tercer proposa una estratègia de paral·lelització pel mètode VOF. L'obstacle principal és que els costos computacionals estan concentrats en les celdes de l'interfase entre fluids. En conseqüència, si la interfase no està ben distribuïda, les estratègies de "domain decomposition" (DD) resulten en distribucions de càrrega desequilibrades. Per tant, la nova estratègia està basada en un procés de balanceig de càrrega complementària a la DD. La seva eficiència en paral·lel ha sigut analitzada utilitzant fins a 1024 CPU-cores, i els resultats obtinguts mostren uns guanys respecte l'estratègia DD de fins a 12x, depenent del tamany de la interfase i de la distribució inicial. El quart capítol descriu la discretització de les equacions de Navier-Stokes per a una sola fase, per després estendre-ho al cas multi-fase. Una de les característiques més importants dels esquemes de discretització, a part de la precisió, és la seva capacitat per conservar discretament l'energia cinètica, específicament en el cas de fluxos turbulents. Per tant, aquest capítol analitza la precisió i propietats de conservació de dos esquemes de malla diferents: "collocated" i "staggered". L'extensió dels esquemes de malla aptes per els casos de una sola fase als casos multi-fase es desenvolupa en el cinquè capítol. En particular, així com en el cas de la simulació de la turbulència les tècniques numèriques han evolucionat per a preservar discretament massa, moment i energia cinètica, els esquemes de malla per a la discretització de fluxos multi-fase han evolucionat per millorar la seva estabilitat i robustesa. Per lo tant, aquest capítol presenta i analitza dos discretitzacions de malla "collocated" i "staggered" particulars, aptes per simular fluxos multi-fase, que afavoreixen la conservació discreta de massa, moment i energia cinètica. Finalment, el capítol sis simula numèricament la inestabilitat de Richtmyer-Meshkov (RM) de dos fluids immiscibles i incompressibles. Aquest capítol es una prova general dels mètodes numèrics desenvolupats al llarg de la tesi. En particular, la inestabilitat ha sigut simulada mitjançant un mètode VOF i un esquema de malla "staggered". Els resultats numèrics corresponents han demostrat la capacitat del sistema discret en obtenir bons resultats per la inestabilitat RM.

  • 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
    Vol. 107, p. 426-437
    DOI: 10.1016/j.apenergy.2013.02.014
    Date of publication: 2013-07-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    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.

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

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

    Read the abstract Read the abstract  Share Reference managers Reference managers Open in new window

    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

    Read the abstract Read the abstract  Share Reference managers Reference managers Open in new window

    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].

  • 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
    p. 198-203
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    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,

     Castro Gonzalez, Jesus; Torras Ortiz, Santiago; 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

    Read the abstract Read the abstract  Share Reference managers Reference managers Open in new window

    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].

  • Acumulador de energía térmica en base a materiales de cambio de fase sólido-líquido y método de fabricación de la unidad

     Oliva Llena, Asensio; Perez Segarra, Carlos David; Rigola Serrano, Joaquim; Castro Gonzalez, Jesus; Oliet Casasayas, Carles; Rodriguez Pérez, Ivette Maria; Lehmkuhl Barba, Oriol; Trias Miquel, Francesc Xavier; Capdevila Paramio, Roser; Alba Queipo, Ramiro; Ordoño Martinez, Manuel Miguel; Morales Ruiz, Sergio
    Date of request: 2013-03-01
    Invention patent

     Share Reference managers Reference managers Open in new window

  • Máquina de absorción refrigerada por aire

     Oliva Llena, Asensio; Perez Segarra, Carlos David; Rigola Serrano, Joaquim; Castro Gonzalez, Jesus; Oliet Casasayas, Carles; Rodriguez Pérez, Ivette Maria; Lehmkuhl Barba, Oriol; Trias Miquel, Francesc Xavier; Capdevila Paramio, Roser; Alba Queipo, Ramiro; Ordoño Martinez, Manuel Miguel; Farnos Baulenas, Joan
    Date of request: 2013-06-14
    Invention patent

     Share Reference managers Reference managers Open in new window

  • 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
    Vol. 12, num. 4, p. 251-259
    DOI: 10.1504/PCFD.2012.048257
    Date of publication: 2012-07-26
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • ISP-1 Deliverable 5.2.3 Modelling optimization

     Castro Gonzalez, Jesus; Perez Segarra, Carlos David; Rigola Serrano, Joaquim; Morales Ruiz, Sergio; Torras Ortiz, Santiago; Rodriguez Pérez, Ivette Maria; Oliva Llena, Asensio
    Date: 2012
    Report

     Share Reference managers Reference managers Open in new window

  • 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
    Competitive project

     Share

  • 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
    p. 871-874
    Presentation's date: 2012-09-26
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • 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

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • 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
    p. 665-673
    Presentation's date: 2012-09-04
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • 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 Ruiz, 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

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • 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
    p. 1 (920)-8 (927)
    Presentation's date: 2012-06-26
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • Access to the full text
    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
    p. 584-591
    Presentation's date: 2012-09-04
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • Access to the full text
    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

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • 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

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • Sistema de almacenamiento de energía térmica combinando material sólido de calor sensible y material de cambio de fase

     Oliva Llena, Asensio; Perez Segarra, Carlos David; Rigola Serrano, Joaquim; Castro Gonzalez, Jesus; Oliet Casasayas, Carles; Rodriguez Pérez, Ivette Maria; Lehmkuhl Barba, Oriol; Trias Miquel, Francesc Xavier; Capdevila Paramio, Roser; Galione Klot, Pedro Andres
    Date of request: 2012-12-27
    Invention patent

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Un sistema para el almacenamiento y recuperación de energía térmica empleando como medio al menos un material de cambio de fase (sólido-líquido) y un material sólido de calor sensible que se encargan de almacenar/recuperar el calor obtenido desde una fuente externa en forma de calor sensible y calor latente de cambio de fase. Dichos materiales están debidamente contenidos en un único tanque, en cuyo interior existen al menos dos zonas, cada una conteniendo un material diferente, y diferenciadas por el rango de temperaturas a las que son sometidas. La configuración más usada consiste en tres diferentes zonas configuradas al interior del tanque: zona caliente, en la parte superior del tanque, donde un material de cambio de fase encapsulado caracterizado por una temperatura de fusión alta está encerrado; zona fría, ubicada en la parte inferior, donde un material de cambio de fase con baja temperatura de fusión está colocado; y una zona media, que contiene un material sólido de calor sensible.

  • 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
    Vol. 34, num. 8, p. 1989-1998
    DOI: 10.1016/j.ijrefrig.2011.02.006
    Date of publication: 2011-12-01
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • 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
    Vol. 11, num. 6, p. 350-362
    DOI: 10.1504/PCFD.2011.042845
    Date of publication: 2011
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • ISP-1 Deliverable 5.2.2 Study report Including Computations Results

     Castro Gonzalez, Jesus; Perez Segarra, Carlos David; Rigola Serrano, Joaquim; Morales Ruiz, Sergio; Rodriguez Pérez, Ivette Maria; Oliva Llena, Asensio
    Date: 2011
    Report

     Share Reference managers Reference managers Open in new window

  • Q-00011

     Rodriguez Pérez, Ivette Maria; Rigola Serrano, Joaquim; Castro Gonzalez, Jesus; Torrades Carné, Francesc; Oliva Llena, Asensio
    Competitive project

     Share

  • Q-00006

     Rigola Serrano, Joaquim; Oliet Casasayas, Carles; Calventus Sole, Yolanda; Puig Montada, Ana M.; Castro Gonzalez, Jesus
    Competitive project

     Share

  • 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
    Competitive project

     Share

  • 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
    Competitive project

     Share

  • Access to the full text
    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
    p. 3157-3162
    Presentation's date: 2011-08-28
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • 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
    p. 1-8
    Presentation's date: 2011-08-21
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • 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
    p. 1-8
    Presentation's date: 2011-07-18
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • Access to the full text
    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
    p. 2946-2957
    Presentation's date: 2011-08-28
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    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
    p. 1-8
    Presentation's date: 2011-07-08
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    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
    p. 1-5
    Presentation's date: 2011-05-16
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    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)

  • 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
    p. 59-66
    Presentation's date: 2011-04-06
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • 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
    Vol. 49, num. 2, p. 692-701
    DOI: 10.1016/j.ijthermalsci.2009.11.009
    Date of publication: 2010-04
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • ISP-1 Deliverable 5.2.1 Preliminary Study: Numerical Simulation of the Heat Accumulator

     Castro Gonzalez, Jesus; Perez Segarra, Carlos David; Rigola Serrano, Joaquim; Morales Ruiz, Sergio; Oliva Llena, Asensio
    Date: 2010
    Report

     Share Reference managers Reference managers Open in new window

  • Sistemas de refrigeració doméstica modulares y de alta energética

     Oliva Llena, Asensio; Lehmkuhl Barba, Oriol; Castro Gonzalez, Jesus; Perez Segarra, Carlos David; Oliet Casasayas, Carles; Rigola Serrano, Joaquim
    Competitive project

     Share

  • 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
    p. 1-15
    Presentation's date: 2010-06-14
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    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
    p. 1-11
    Presentation's date: 2010-08-10
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    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.

  • Access to the full text
    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
    Vol. 48, num. 7, p. 1355-1366
    DOI: 10.1016/j.ijthermalsci.2008.11.021
    Date of publication: 2009-07-01
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    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)

  • 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
    Vol. 56, num. 3, p. 193-210
    DOI: 10.1080/10407780903163082
    Date of publication: 2009-01
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • MAQUINA D'OBSERVACIO SOLAR REFREDADA PER AIRE

     Oliva Llena, Asensio; Garcia Rivera, Eduardo; Farnos Baulenas, Joan; Castro Gonzalez, Jesus
    Competitive project

     Share

  • IN SPACE PROPULSION-1

     Jofre Cruanyes, Lluís; Oliva Llena, Asensio; Morales Ruiz, Sergio; Castro Gonzalez, Jesus; Perez Segarra, Carlos David
    Competitive project

     Share

  • CENTRE TECNOLOGIC TRANSFERENCIA CALOR

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

     Share

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

     Lopez Mas, Joan; Ablanque Mejia, Nicolas; Oliet Casasayas, Carles; Castro Gonzalez, Jesus; Rigola Serrano, Joaquim
    Competitive project

     Share

  • 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
    Vol. 48, num. 4, p. 708-721
    DOI: doi:10.1016/j.ijthermalsci.2008.06.002
    Date of publication: 2009-04
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Proyecto FERASOL. Informe de seguimiento año 2007

     Castro Gonzalez, Jesus; Rigola Serrano, Joaquim; Oliet Casasayas, Carles
    Date: 2008-04
    Report

     Share Reference managers Reference managers Open in new window

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

     Oliet Casasayas, Carles; Perez Segarra, Carlos David; Castro Gonzalez, Jesus
    Competitive project

     Share