Experimental Measurements and CFD Results of Liquid Film Thickness in Vertical Downward Air-Water Annular Flow

[EN] Annular gas¿liquid flows have been extensively studied over the years. However, the nonlinear behavior of the interface is still currently the subject of study by multiple researchers worldwide. The appearance of a liquid layer on the wall and its turbulent behavior support the heat exchange of multiple systems in the industrial field. Research in this area allows the optimization of these installations as well as the analysis of possible safety problems if the liquid film disappears. This study first shows some of the most important findings obtained in the GEPELON experimental facility (GEneración de PElícula ONdulatoria or Wavy Film Generator). The facility was built in order to analyze the behavior of the liquid film in annular downward air¿water flow. The experimental range of the inlet conditions is 800¿8000 for the ReL and 0¿110,000 for the Reg. Measurements for the mean film thickness show a fairly good agreement with the empirical correlations and the measurements of other authors. One of the most demanded applications of this type of measurements is the validation of computational dynamics or CFD codes. Therefore, the experiment has been modeled using Ansys CFX software, and the simulation results have been compared with the experimental ones. This article outlines some of the reasons why two-phase flow simulations are currently challenging and how the codes are able to overcome them. Simulation predictions are fairly close to the experimental measurements, and the mean film thickness evolution when changing the boundary conditions also shows a good agreement.The authors are indebted to the plan of I+D support of the EXMOTRANSIN project ENE2016-79489-C2-1-P.Rivera-Durán, Y.; J. L. Muñoz-Cobo; A. Escrivá; C. Berna; Y. Córdova (2022). Experimental Measurements and CFD Results of Liquid Film Thickness in Vertical Downward Air-Water Annular Flow. International Journal of Computational Methods and Experimental Measurements. 10(2):93-103. https://doi.org/10.2495/CMEM-V10-N2-93-1039310310

Experiments in free falling and downward cocurrent annular flows-Characterization of liquid films and interfacial waves

[EN] Falling liquid films and downward cocurrent flows in rounded shape pipes have been experimentally studied during the last decades, estimating the evolution of its major characteristics. The most important variables during the formation and growth of surface waves in falling downward flows have been measured using conductance probes. The main objective of the current research paper is to study the dependency of the characteristics of the thin liquid layer for downward cocurrent annular flows. The GEPELON experimental facility consists of a vertical pipe with 3.8 m of useful test length. Two pipe diameters have been analysed in this experimental study, 42 and 30 mm, in which the range covered by the liquid Reynolds number varies between 570 and 8500 and 800-7900 respectively, while the gas Reynolds numbers vary from 0 to 7.9.10(4) and from 0 to 1.1.10(5) respectively for the mentioned pipe diameters. Up to five conductance probes have been placed along the pipes test sections to capture the liquid film thickness fluctuations along time at different distances of the pipe entrance for both developing and fully developed regions. After the study and analysis of the experimental data, the central point of this paper has been the development of new correlations for the liquid film thicknesses and the two major properties of the interfacial waves. Their adjustment procedure has been carried out in terms of dimensionless numbers, aiming to provide more general relationships. In particular, the magnitudes that characterise the interface behavior have been measured, particularly film thicknesses, average disturbance wave amplitudes, and disturbance wave frequencies for each boundary condition. An additional part of the document contains an extensive comparison between the results obtained in this study and the data and expressions of other authors. It has been confirmed the significant dispersion existing among different researchers, especially when analysing variables related to the interfacial waves. This highlights the lack of knowledge in some aspects even today. The different correlations proposed have been calculated based on the best fit of the data from all the series of experiments carried out in this study. Comparisons of the behaviour of these correlations with data from other researchers have also been included.This research is supported by the EXMOTRANSIN project ENE2016-79489-C2-1-P included in the I + D Spanish plan. Funding for open access charge: CRUE-Universitat Politècnica de València.Rivera-Durán, Y.; Berna, C.; Muñoz-Cobo, JL.; Escrivá, A.; Córdova, Y. (2022). Experiments in free falling and downward cocurrent annular flows-Characterization of liquid films and interfacial waves. Nuclear Engineering and Design. 392:1-23. https://doi.org/10.1016/j.nucengdes.2022.11176912339

Experimental Characterization of the Dimensionless Momentum Length for Submerged Jet Discharges of Air-Steam Mixtures into Stagnant Water

[EN] A very efficient method of condensing the steam in various industrial applications is the steam direct discharge into pools with subcooled water. This kind of condensation is known as Direct Contact Condensation (DCC), by providing high heat transfer and mass exchange capacity, the steam condenses quickly. In the past few decades, many experiments have been carried out on the submerged jets of non-condensable gases and pure steam in pools, supplying much information of interest, but efforts are still being made to obtain more information. In particular, the research of steam and non-condensable gas mixtures is of great interest to the chemical, energy, and nuclear industry. Consequently, this study investigates the discharge behavior of air-steam mixtures in a pool with subcooled water by direct visualization techniques using a high-speed camera. To know the behavior of the dimensionless momentum length, tests were carried out considering several initial discharge conditions such as nozzle diameter, percentage of mixture, and flow rates. After image acquisition, a series of complex processing, filtering, and post-processing procedures are applied using a subroutine in MATLAB. The momentum length of the jet was measured and found to be heavily influenced by the nozzle diameter, the jet velocity, and the mixture percentage. A correlation is obtained for the dimensionless momentum length of the horizontal jet that depends on the Froude and Mach numbers.The authors would like to acknowledge the support provided through the Spanish project EXMOTRANSIN ENE2016-79489-C2-1-P and the Santiago Grisolía Program for the training of research personnel.Y. Córdova; D. Blanco; C. Berna; J. L. Muñoz-Cobo; A. Escrivá; Rivera-Durán, Y. (2022). Experimental Characterization of the Dimensionless Momentum Length for Submerged Jet Discharges of Air-Steam Mixtures into Stagnant Water. International Journal of Computational Methods and Experimental Measurements. 10(3):195-210. https://doi.org/10.2495/CMEM-V10-N3-195-21019521010

Metabolismo urbano de nutrientes: reúso y compostaje de residuos asociados con la porcicultura en Ciudad Juárez

Se documentan las prácticas de manejo y los volúmenes de residuos orgánicos asociados con la porcicultura periurbana (escamocha y excretas), así como el manejo de las podas municipales que permitirían cerrar ciclos biogeoquímicos en Ciudad Juárez. Se determinó que, con 177 toneladas al año, existen suficientes podas municipales para compostar las 1967 toneladas anuales de excretas porcinas generadas, y que existe tanto la necesidad como la superficie suficiente para utilizar ese compost en las áreas verdes municipales. En este análisis parcial del metabolismo urbano de la ciudad, se demuestra que se tienen cubiertos los requisitos para el establecimiento del proceso de compostaje en la localidad (el interés de los actores, la experiencia en el proceso, la infraestructura mínima)

Profile of Economic Units on the Manufacturing Sector: An Approach in the Case of Mexico

The aim of the study was to identify factors which describe the profile of economic units (EUs) in Mexico. For this purpose, were consulted the databases of the Ministry of Labor and Social Welfare (MLSW, “Secretaría del trabajo y Previsión Social” - STPS, Mexico) and the National Institute of Statistic, Geography and Informatics (NISGI, “Instituto Nacional de Estadística, Geografía e Informática” - INEGI, Mexico), as institutions responsible for carry out officially, the application of surveys through the National Survey on Employment, Wages, Technology and Training in the manufacturing sector (NSEWTT, “Encuesta Nacional de Empleo, Salarios, Tecnología y Capacitación” - ENESTYC, Mexico). With the capture of these surveys by the institutions responsible, subsequently allow us determine the factors which describe the profile of the economic units. With this research we identified eight factors, which describe the profile of the economic units, being these: Establishment’s characteristics (F1), Production and organization (F2), Market (F4), Quality control and technology (F5), Employment Forms (F6), Salaries (F7), Training and Health and safety (F8). DOI: 10.5901/mjss.2015.v6n4p2

Generalized Toda Theory from Six Dimensions and the Conifold

Recently, a physical derivation of the Alday-Gaiotto-Tachikawa correspondence has been put forward. A crucial role is played by the complex Chern-Simons theory arising in the 3d-3d correspondence, whose boundary modes lead to Toda theory on a Riemann surface. We explore several features of this derivation and subsequently argue that it can be extended to a generalization of the AGT correspondence. The latter involves codimension two defects in six dimensions that wrap the Riemann surface. We use a purely geometrical description of these defects and find that the generalized AGT setup can be modeled in a pole region using generalized conifolds. Furthermore, we argue that the ordinary conifold clarifies several features of the derivation of the original AGT correspondence.Comment: 27+2 pages, 3 figure

Evaluación de desempeño al Acompañamiento Pedagógico a distancia : fortalecimiento de prácticas pedagógicas remotas de docentes en el contexto de la Covid-19

La evaluación buscó analizar el diseño y el proceso de implementación del Acompañamiento Pedagógico a Distancia (APD) en el contexto de la emergencia sanitaria, con miras a generar evidencia que permita mejorar la gestión de la intervención y fortalecer la capacidad de las Direcciones del Minedu para la toma de decisiones

Spectroscopic Study of SU UMa-type Dwarf Nova YZ Cnc during its 2002 Superoutburst

We report time-resolved spectroscopic observations of the SU Ursae Majoris dwarf nova, YZ Cnc, for 2 nights over 11 hrs during its 2002 January superoutburst. The spectra only show absorption-line profiles in the first day. But the lines display blue and red troughs, with ``W'' profiles in the second day. The radial velocity curve of the absorption troughs and emission peaks of H$\beta$ has an amplitude of $49\pm10$ km s$^{-1}$ and a phase offset of $-0.07\pm0.04$, which are very similar to those measured in quiescence; however, the $\gamma$ velocity deviates strongly from the systemic velocity measured in quiescence, showing variation of the order of $\pm$60 km s$^{-1}$. And large shifts of $\sim$70 km s$^{-1}$ and $\sim$0.09, for the orbital-averaged velocity and phase respectively, are also found in our observations. All these phenomena can be well explained with a precession of an eccentric disk and we conclude that these phenomena are the characteristic products of an eccentric accretion disk.Comment: 11 pages, 4 figures, accepted for publication in ChJA

Redes complejas de interacción con Tic y personal entre alumnos de la escuela secundaria José María Morelos y Pavón de Tenosique, Tabasco

En este estudio se analizan las redes de interacción por medio de siete Tecnologías de la Información y Comunicación (TIC) e interacción personal entre los alumnos de la escuela secundaria Federal José María Morelos y Pavón, localizada en el municipio de Tenosique, Tabasco, México. El objetivo fue analizar las propiedades topológicas de las redes, estudiar las similitudes y diferencias entre estas, dar una explicación del por qué se manifiestan en el sistema estudiado. Se diseñó una encuesta donde los alumnos señalaron las relaciones de amistad que mantienen unos con otros y los medios por los que se relacionan. Se aplicaron métodos algorítmicos para transformar los datos de las encuestas en redes complejas. Al finalizar el estudio se observó que los alumnos tienen bien definidas las preferencias de comunicación electrónica, siendo Facebook y WhatsApp las TIC más utilizadas. Igual se concluyó que la comunicación personal aún prevalece sobre la electrónica, pero la diferencia entre éstas no es significativ