Muñoz-Cobo González, José Luís

ORCID

0000-0002-4512-7991

Panorama page

https://www.upv.es/ficha-personal/jlcobos

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Desarrollo de Nuevas Correlaciones para Flujo Anular
(Sociedad Nuclear Española, 2013-09) Berna Escriche, César; Escrivá Castells, Facundo Alberto; Muñoz-Cobo González, José Luís; Herranz, L.E.; Departamento de Ingeniería Química y Nuclear; Departamento de Estadística e Investigación Operativa Aplicadas y Calidad; Instituto Universitario de Investigación de Ingeniería Energética; Escuela Técnica Superior de Ingeniería Industrial; Escuela Técnica Superior de Ingeniería Informática
El presente trabajo explora la extensa literatura existente y propone nuevas correlaciones para el estudio del flujo anular. El interés de este trabajo se centra, por una parte, en la recopilación de la dispersa y abundante información existente y, por otra parte, en el desarrollo de nuevas correlaciones para la determinación de las principales magnitudes que caracterizan al flujo anular a partir de datos experimentales encontrados en la literatura abierta
An Eulerian-Lagrangian open source solver for bubbly flow in vertical pipes
(Sociedad Nuclear Española, 2014-10) Peña Monferrer, Carlos; Muñoz-Cobo González, José Luís; Monrós Andreu, G.; Martinez Cuenca, R.; Chiva Vicent, Sergio
Air-water two-phase flow is present in natural and industrial processes of different nature as nuclear reactors. An accurate local prediction of the boiling flow could support safety and operation analyses of nuclear reactors. A new Eulerian-Lagrangian approach is investigated in this contribution. A new solver has been developed and implemented in the framework of the open source package OpenFOAM R and based on the PIMPLE algorithm coupled with the Lagrangian equation of motion has been implemented for computing incompressible bubbly flows. Each bubble is divided in equivolumetric volumes and tracked into the Eulerian mesh for an appropriate assignment of the effect of the bubble in the cell without resolving the interface. The coupling between phases is done considering in the momentum equation the interfacial forces and bubble induced contribution along the bubble path during an Eulerian time step. The bouncing of the bubbles between themselves and the wall is modeled with a dynamic soft sphere model. The computational results obtained for different flow conditions are validated with the recently released experimental data on upward pipe flow. The test section used is a 52 mm pipe of 5500 mm of length maintained under adiabatic conditions with air and water circulating fluids working with inlet velocity ranges of 0-2 m/s and 0-0.3 m/s for the continuous and dispersed phase respectively. Averaged results of radial distribution for void fraction, chord length, turbulence kinetic energy, dispersed and continuous velocity profiles show a good agreement among different flow conditions.
On the One-Dimensional Modeling of Vertical Upward Bubbly Flow
(Hindawi Limited, 2018) Peña-Monferrer, C.; Gómez-Zarzuela, C.; Chiva, S.; Miró Herrero, Rafael; Verdú Martín, Gumersindo Jesús; Muñoz-Cobo González, José Luís; Departamento de Ingeniería Química y Nuclear; Escuela Técnica Superior de Ingeniería Industrial; Instituto Universitario de Seguridad Industrial, Radiofísica y Medioambiental; Ministerio de Economía y Competitividad; MINISTERIO DE ECONOMIA INDUSTRIA Y COMPETITIVIDAD
[EN] The one-dimensional two-fluid model approach has been traditionally used in thermal-hydraulics codes for the analysis of transients and accidents in water¿cooled nuclear power plants. This paper investigates the performance of RELAP5/MOD3 predicting vertical upward bubbly flow at low velocity conditions. For bubbly flow and vertical pipes, this code applies the drift- velocity approach, showing important discrepancies with the experiments compared. Then, we use a classical formulation of the drag coefficient approach to evaluate the performance of both approaches. This is based on the critical Weber criteria and includes several assumptions for the calculation of the interfacial area and bubble size that are evaluated in this work. A more accurate drag coefficient approach is proposed and implemented in RELAP5/MOD3. Instead of using the Weber criteria, the bubble size distribution is directly considered. This allows the calculation of the interfacial area directly from the definition of Sauter mean diameter of a distribution. The results show that only the proposed approach was able to predict all the flow characteristics, in particular the bubble size and interfacial area concentration. Finally, the computational results are analyzed and validated with cross-section area average measurements of void fraction, dispersed phase velocity, bubble size, and interfacial area concentration.
A Comparative Analysis of Conductance Probes and High-Speed Camera Measurements for Interfacial Behavior in Annular Air-Water Flow
(MDPI AG, 2023-10) Rivera, Yago; Bidon, Maxime; Muñoz-Cobo González, José Luís; Berna Escriche, César; Escrivá Castells, Facundo Alberto; Departamento de Ingeniería Química y Nuclear; Departamento de Estadística e Investigación Operativa Aplicadas y Calidad; Instituto Universitario de Investigación de Ingeniería Energética; Escuela Técnica Superior de Ingeniería Industrial; Escuela Técnica Superior de Ingeniería Informática; Agencia Estatal de Investigación
[EN] Different techniques are used to analyze annular flow, but the more interesting ones are those techniques that do not perturb the flow and provide enough resolution to clearly distinguish the interfacial phenomena that take place at the interface, especially the disturbance waves (DW) and the ripple waves (DW). The understanding of these events is important because it influences the heat and mass transfer taking place through the thin film formed near the walls in this flow regime. The laser-induced fluorescence (LIF) and the three-electrode conductance probe are two commonly used techniques to study experimentally annular flow phenomena. In this paper, a set of experiments at different temperatures of 20 degrees C, 30 degrees C and 40 degrees C and different liquid Reynolds numbers have been performed in the annular flow regime, the characteristic of the DW and RW as average height and frequency of these waves has been measured by both techniques LIF and conductance probes. In addition, we also measured the mean film thickness. It was found that the mean film thickness and the DW height are practically the same when measured by both techniques; however, the height of the RW is smaller when measured by the conductance probe and this difference diminishes when the temperature increases.
Review of droplet entrainment in annular flow: Characterization of the entrained droplets
(Elsevier, 2015-03) Berna Escriche, César; Escrivá Castells, Facundo Alberto; Muñoz-Cobo González, José Luís; Herranz, L.E.; Departamento de Ingeniería Química y Nuclear; Departamento de Estadística e Investigación Operativa Aplicadas y Calidad; Instituto Universitario de Investigación de Ingeniería Energética; Escuela Técnica Superior de Ingeniería Industrial; Escuela Técnica Superior de Ingeniería Informática; Ministerio de Ciencia e Innovación
[EN] Annular flow is characterized by a thin liquid film flowing on the pipe wall and a high velocity gas core flowing in its center, which normally carries liquid droplets. This review presents and analyzes most of the extensive literature existing on the annular two-phase flow, focusing specifically on the analysis of the main phenomena that are involved. In particular, the paper focuses on the study of the liquid droplets that are entrained by the gas stream from the gas-liquid interface, due to the strong influence that these droplets exert in many important parameters of both, flow and heat transfer processes. Consequently, it is important to be able to know the maximum amount of information about them, in order to characterize droplets' size and velocity, and to determine the amount of them that are entrained into the gas stream and, finally, apply this knowledge in all processes in which annular flow is involved. This review analyzes most of the extensive literature on droplets, specifically analyzes its main characteristics once they have been formed, such as its sizes, speeds and total amount. A vast amount of data has been found in the open literature and collected here. Their analysis leads to two major observations: their huge scattering and the existence of remaining knowledge gaps. Some of the experimental data have been also used to derive new correlations on variables as important as amount and size of entrained droplets.
An experimental investigation on the characteristics of submerged horizontal gas jets in liquid ambient
(Elsevier, 2014-02) Harby Mohamed Abd Alaal, Khaled; Chiva Vicent, Sergio; Muñoz-Cobo González, José Luís; Ministerio de Ciencia e Innovación
Gas injections into liquid are prevalent in the natural environment and are essential in industrial applications, they can lead to complex flow. The flow structure and processes are essentially unsteady and turbulent. In this study, a set of experiments were carried out to investigate the behavior of horizontal round noncondensing gas jets that discharge in a stagnant water ambient, considering subsonic and sonic jet exit conditions. A flow visualization technique using a CCD camera, which allowed simultaneous measurements, was used to investigate such flows. This technique provided a direct measurement of the interfacial behavior between the gas jet and the liquid ambient. Two different methods, the summation and the statistical one were used to obtain and analyze the experimental results, and we have found that both methods yield almost identical results. The results showed that the injector diameter and the Froude number play an important role in dictating both the jet pinch-off and the jet interface unsteadiness. The maximum location before the jet pinchoff is shown to have a logarithmic relation with the Froude number for all the jet diameters. The jet penetration length was measured in the momentum and buoyant regimes respectively and it was found to be strongly influenced by the nozzle diameter and the Froude number as well as by the mass and momentum flow rates of the injected jet. Jet spreading which is indicative of liquid entrainment is also shown to increase with the Froude number and the injector diameters. Also it was found that the Froude number plays an important role in dictating the expansion jet angle and the jet half-width. These magnitudes were obtained from recorded time-averaged images and finally empirical correlations have been developed to predict these parameters.
CFD simulation plus uncertainty quantification of the mixing of two fluid with different density for the Cold-Leg mixing benchmark
(Elsevier, 2021-11) Rivera-Durán, Yago; Muñoz-Cobo González, José Luís; Berna Escriche, César; Escrivá Castells, Facundo Alberto; Vela, E.; Departamento de Ingeniería Química y Nuclear; Departamento de Estadística e Investigación Operativa Aplicadas y Calidad; Instituto Universitario de Investigación de Ingeniería Energética; Escuela Técnica Superior de Ingeniería Industrial; Escuela Técnica Superior de Ingeniería Informática; Consejo de Seguridad Nuclear; Universitat Politècnica de València
[EN] This document describes the details of the simulations and uncertainty quantification of the Cold-Leg Mixing benchmark performed at the Institute for Energy Engineering (Polytechnic University of Valencia, Spain). The experiment, carried out by Texas A&M University, consists of the mixing of two water flows with different densities inside two tanks joined by a pipeline or cold leg. The tank that accumulates the low-density water and its connection to the cold leg are designed to create a downcomer like the one found in a PWR reactor vessel. On the other hand, the high-density water reservoir represents the cold-water injection accumulator. The method of Polynomial Chaos Expansion (PCE) based on Gaussian Quadrature is applied to calculate the uncertainty of the results, and a model created in Ansys CFX is developed to carry out the simulations. A 5th order Polynomial Chaos Expansion by Gaussian-Hermite Quadrature has been applied using as uncertain parameter the density difference between the mixing fluids. Therefore, five simulations have been done for both the open and the blind test. This methodology aims to provide an efficient solution since PCE solved by Gaussian Quadrature allows to obtain uncertainty quantification through a low number of simulations when the amount of uncertain input variables is low. It has been observed that the turbulence model significantly affects the results obtained, being the LES model the only one able to reproduce the real behavior consistently. Simulation results show a good agreement with experimental data for the cold-leg measurement zone while, in the downcomer a slightly different velocity profile than the one measured experimentally is obtained. The concentration profile of each fluid shows a gap in the transition zone that does not seem to agree with the velocity results. That behavior remains for higher time averages when comparing simulation results with experimental measurements.
Estudio de los Procesos de Captura de Aerosoles en Piscina para Inyecciones de Jets Gaseosos a Altas Velocidades: Mejoras del Código SPARC90
(Grupo Senda, 2012-10-17) Berna Escriche, César; Escrivá, Alberto; Muñoz-Cobo González, José Luís; Herranz Puebla, Luis Enrique; Departamento de Estadística e Investigación Operativa Aplicadas y Calidad; Instituto Universitario de Investigación de Ingeniería Energética; Escuela Técnica Superior de Ingeniería Informática
[ES] El código SPARC90 fue desarrollado para el cálculo de la captura de aerosoles en piscina durante procesos de descarga en accidentes nucleares a bajas velocidades del gas, régimen de inyección en forma de glóbulo. Sin embargo, hay secuencias de accidentes en las cuales los gases son inyectados a velocidades muy altas, teniéndose en estos casos nuevos mecanismos de captura. Bajo este régimen de inyección en forma de jet el mecanismo de rotura de las crestas de la ola produce el arranque de gotas de la interfase gas-líquido, siendo parte de ellas arrastradas hacia el centro del gas. Estas gotitas tienen el potencial para capturar los aerosoles transportados por el jet gaseoso, principalmente por impacto inercial e interceptación. Dicha extracción continúa mientras las diferencias de velocidades entre el jet gaseoso y la lámina líquida donde las gotas son arrancadas superan un valor límite, llamado velocidad de inicio del arrastre. Si bien cabe puntualizar que muy pocos experimentos se han realizado bajo estas condiciones. Por todo ello, el presente trabajo explora el comportamiento hidrodinámico del jet bajo estas condiciones y, basado en las ecuaciones existentes para la captura de aerosoles, presenta las expresiones existentes para sus variables fundamentales, tales como: población, tamaño y velocidad de las gotas arrancadas. Las diferentes expresiones que se encuentran en la literatura han sido analizadas, introduciéndose en una versión modificada del código SPARC90 las que se consideran más adecuadas. Finalmente, se han comparado en términos de factores de descontaminación los resultados obtenidos mediante el código SPARC original y el modificado (SPARC90-Jet) para las condiciones de un accidente SGTR (rotura de tubos en el generador de vapor). A pesar de quedar pendiente mucho trabajo por delante, se pone de relieve la importancia de los procesos de captura de aerosoles en la región próxima a la rotura para inyecciones a altas velocidades, régimen de inyección en forma de jet, mostrando cuanto diferentes son estos mecanismos de captura respecto a los existentes en la inyección en régimen globular.
Characterization of the gas-liquid interfacial waves in vertical upward co-current annular flows
(Elsevier, 2019-05) Cuadros-Orón, José Luis; Rivera-Durán, Yago; Berna Escriche, César; Escrivá Castells, Facundo Alberto; Muñoz-Cobo González, José Luís; Monrós-Andreu, G.; Chiva, S.; Departamento de Ingeniería Química y Nuclear; Departamento de Estadística e Investigación Operativa Aplicadas y Calidad; Instituto Universitario de Investigación de Ingeniería Energética; Escuela Técnica Superior de Ingeniería Industrial; Escuela Técnica Superior de Ingeniería Informática; Ministerio de Economía y Competitividad
[EN] For more than fifty years, hundreds of research works have focused on the study of annular flow because of its huge importance in many industrial processes, for instance, chemical, petroleum, etc., being of particular interest in nuclear industry. Specifically, interfacial waves play a vital role in the mass, momentum and energy transference processes between gas and liquid phases. This paper describes the new experimental measurements of vertical upward co-current two-phase gas-liquid flow carried out in a tube with an inner diameter of 44 mm. The liquid film thickness and the major characteristics of the interfacial waves have been measured using a non-intrusive instrument, a conductance probe. The physical phenomenon in which this device is based is the change in the electrical conductivity between air and water, i.e., the electrical signal collected in the sensor receiver depends on the thickness of the liquid film layer. The experimental measurements range from 2000 to 3500 l/min for the gas volumetric flow rate, and from 4 to 10 l/min for the liquid volumetric flow rate. Correlation of the experimental measurements of liquid film thickness and the major properties of the interfacial waves have been analyzed using non-dimensional numbers. An important part of the document focuses on the comparison of the experimental data and the fitting correlations against several of the most widely used expressions. Throughout this paper, in addition to present all the available correlations, the existing scattering found when comparing against other expressions have been also confirmed, underlining the existence of gaps of knowledge even today. Emphasize that the proposed correlations are the ones that better fit the data of all experimental series carried out under the present study for the analyzed variables, with almost all the experimental points covered by the +/- 10% error bands of the new correlations.
Comparison of Refractive Index Matching Techniques and PLIF40 Measurements in Annular Flow
(MDPI AG, 2023-04-05) Rivera, Yago; Bascou, Dorian; Blanco de las Muelas, David; Álvarez Piñeiro, Lucas; Berna Escriche, César; Muñoz-Cobo González, José Luís; Escrivá Castells, Facundo Alberto; Departamento de Ingeniería Química y Nuclear; Departamento de Estadística e Investigación Operativa Aplicadas y Calidad; Instituto Universitario de Investigación de Ingeniería Energética; Escuela Técnica Superior de Ingeniería Industrial; Escuela Técnica Superior de Ingeniería Informática; Agencia Estatal de Investigación; Ministerio de Economía, Industria y Competitividad
[EN] This paper investigates non-invasive techniques for annular two-phase flow analysis, focusing on liquid film characterization to understand the interfacial phenomena that are crucial for heat and mass transfer. Limited methods allow the study of the temporal and spatial evolution of liquid film, such as Planar Laser-Induced Fluorescence (PLIF). However, this method possesses optical challenges, leading to the need for improved techniques to mitigate refraction and reflection, such as Refractive Index Matching (RIM). This study utilizes an experimental annular flow facility to analyze both RIM and non-RIM PLIF over a range of liquid Reynolds numbers from 4200 to 10,400. Three configurations-PLIF RIM90, PLIF RIM40, and PLIF nRIM40-are compared from both qualitative and quantitative perspectives. In the quantitative analysis, key variables of the liquid film are measured, namely mean film thickness, disturbance wave height, and frequency. Variations in the analyzed variables indicate minor deviations, which are not likely to be caused by the technique used. However, all three methodologies exhibited errors that are estimated to be within a maximum of 10%, with a mean value of approximately 8%.