Modeling of wastewater treatment processes with hydrosludge

The pressure for Water Resource Recovery Facilities (WRRF) operators to efficiently treat wastewater is greater than ever because of the water crisis, produced by the climate change effects and more restrictive regulations. Technicians and researchers need to evaluate WRRF performance to ensure maximum efficiency. For this purpose, numerical techniques, such as CFD, have been widely applied to the wastewater sector to model biological reactors and secondary settling tanks with high spatial and temporal accuracy. However, limitations such as complexity and learning curve prevent extending CFD usage among wastewater modeling experts. This paper presents HydroSludge, a framework that provides a series of tools that simplify the implementation of the processes and workflows in a WRRF. This work leverages HydroSludge to preprocess existing data, aid the meshing process, and perform CFD simulations. Its intuitive interface proves itself as an effective tool to increase the efficiency of wastewater treatment. Practitioner points This paper introduces a software platform specifically oriented to WRRF, named HydroSludge, which provides easy access to the most widespread and leading CFD simulation software, OpenFOAM. Hydrosludge is intended to be used by WRRF operators, bringing a more wizard-like, automatic, and intuitive usage. Meshing assistance, submersible mixers, biological models, and distributed parallel computing are the most remarkable features included in HydroSludge. With the provided study cases, HydroSludge has proven to be a crucial tool for operators, managers, and researchers in WRRF

CFD Turbulence Study of PWR Spacer-Grids in a Rod Bundle

Nuclear fuel bundles include spacers essentially for mechanical stability and to influence the flow dynamics and heat transfer phenomena along the fuel rods. This work presents the analysis of the turbulence effects of a split-type and swirl-type spacer-grid geometries on single phase in a PWR (pressurized water reactor) rod bundle. Various computational fluid dynamics (CFD) calculations have been performed and the results validated with the experiments of the OECD/NEA-KAERI rod bundle CFD blind benchmark exercise on turbulent mixing in a rod bundle with spacers at the MATiS-H facility. Simulation of turbulent phenomena downstream of the spacer-grid presents high complexity issues; a wide range of length scales are present in the domain increasing the difficulty of defining in detail the transient nature of turbulent flowwith ordinary turbulence models. This paper contains a complete description of the procedure to obtain a validated CFD model for the simulation of the spacer-grids. Calculations were performed with the commercial code ANSYS CFX using large eddy simulation (LES) turbulence model and the CFD modeling procedure validated by comparison with measurements to determine their suitability in the prediction of the turbulence phenomena.The authors sincerely thank the Consejo de Seguridad Nuclear (CSN) (Spanish Nuclear Safety Council) and the "Plan Nacional de I+D+i" Project EXPERTISER ENE2010-21368-C02-01 and ENE2010-21368-C02-02 for funding the project.Peña Monferrer, C.; Muñoz-Cobo González, JL.; Chiva Vicent, S. (2014). CFD Turbulence Study of PWR Spacer-Grids in a Rod Bundle. Science and Technology of Nuclear Installations. 2014:1-15. doi:10.1155/2014/635651S1152014Pioro, I. L., Groeneveld, D. C., Doerffer, S. S., Guo, Y., Cheng, S. C., & Vasić, A. (2002). Effects of flow obstacles on the critical heat flux in a vertical tube cooled with upward flow of R-134a. International Journal of Heat and Mass Transfer, 45(22), 4417-4433. doi:10.1016/s0017-9310(02)00150-3Yang, S. K., & Chung, M. K. (1998). Turbulent Flow Through Spacer Grids in Rod Bundles. Journal of Fluids Engineering, 120(4), 786-791. doi:10.1115/1.2820739Caraghiaur, D., Anglart, H., & Frid, W. (2009). Experimental investigation of turbulent flow through spacer grids in fuel rod bundles. Nuclear Engineering and Design, 239(10), 2013-2021. doi:10.1016/j.nucengdes.2009.05.029Dominguez-Ontiveros, E. E., Hassan, Y. A., Conner, M. E., & Karoutas, Z. (2012). Experimental benchmark data for PWR rod bundle with spacer-grids. Nuclear Engineering and Design, 253, 396-405. doi:10.1016/j.nucengdes.2012.09.003Nematollahi, M. R., & Nazifi, M. (2008). Enhancement of heat transfer in a typical pressurized water reactor by different mixing vanes on spacer grids. Energy Conversion and Management, 49(7), 1981-1988. doi:10.1016/j.enconman.2007.12.016Pazirandeh, A., Ghaseminejad, S., & Ghaseminejad, M. (2011). Effects of various spacer grid modeling on the neutronic parameters of the VVER-1000 reactor. Annals of Nuclear Energy, 38(9), 1978-1986. doi:10.1016/j.anucene.2011.04.020Jayanti, S., & Rajesh Reddy, K. (2013). Effect of spacer grids on CHF in nuclear rod bundles. Nuclear Engineering and Design, 261, 66-75. doi:10.1016/j.nucengdes.2013.03.044SMAGORINSKY, J. (1963). GENERAL CIRCULATION EXPERIMENTS WITH THE PRIMITIVE EQUATIONS. Monthly Weather Review, 91(3), 99-164. doi:10.1175/1520-0493(1963)0912.3.co;2Germano, M., Piomelli, U., Moin, P., & Cabot, W. H. (1991). A dynamic subgrid‐scale eddy viscosity model. Physics of Fluids A: Fluid Dynamics, 3(7), 1760-1765. doi:10.1063/1.857955Deardorff, J. W. (1970). A numerical study of three-dimensional turbulent channel flow at large Reynolds numbers. Journal of Fluid Mechanics, 41(2), 453-480. doi:10.1017/s0022112070000691Deardorff, J. W. (1973). The Use of Subgrid Transport Equations in a Three-Dimensional Model of Atmospheric Turbulence. Journal of Fluids Engineering, 95(3), 429-438. doi:10.1115/1.3447047Ciofalo, M. (1994). Large-Eddy Simulation: A Critical Survey of Models and Applications. Advances in Heat Transfer, 321-419. doi:10.1016/s0065-2717(08)70196-5Lesieur, M., & Metais, O. (1996). New Trends in Large-Eddy Simulations of Turbulence. Annual Review of Fluid Mechanics, 28(1), 45-82. doi:10.1146/annurev.fl.28.010196.000401Guermond, J.-L., Oden, J. T., & Prudhomme, S. (2004). Mathematical Perspectives on Large Eddy Simulation Models for Turbulent Flows. Journal of Mathematical Fluid Mechanics, 6(2), 194-248. doi:10.1007/s00021-003-0091-5Lee, J. R., Kim, J., & Song, C.-H. (2014). Synthesis of the turbulent mixing in a rod bundle with vaned spacer grids based on the OECD-KAERI CFD benchmark exercise. Nuclear Engineering and Design, 279, 3-18. doi:10.1016/j.nucengdes.2014.03.008Meyers, J., Geurts, B. J., & Sagaut, P. (Eds.). (2008). Quality and Reliability of Large-Eddy Simulations. Ercoftac Series. doi:10.1007/978-1-4020-8578-

Simulación con TRACE del Transitorio de Parada Automática por Transferencia de 400 KV a 132 KV (RESA) en la Central Nuclear de Trillo

La presente ponencia presenta un análisis realizado con el código TRACE del transitorio RESA que tuvo lugar en la Central Nuclear de Trillo en el año 2001. La comparación de los resultados de TRACE con los de planta puede considerarse satisfactoria, por lo que el código TRACE es una buena herramienta predictiva para este tipo de transitorios.Romero Hamers, A.; Muñoz-Cobo González, JL.; Chiva Vicent, S.; Posada, JM.; Martínez-Murillo, J. (2013). Simulación con TRACE del Transitorio de Parada Automática por Transferencia de 400 KV a 132 KV (RESA) en la Central Nuclear de Trillo. Sociedad Nuclear Española. http://hdl.handle.net/10251/71623

An Eulerian-Lagrangian open source solver for bubbly flow in vertical pipes

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.Peña Monferrer, C.; Muñoz-Cobo González, JL.; Monrós Andreu, G.; Martinez Cuenca, R.; Chiva Vicent, S. (2014). An Eulerian-Lagrangian open source solver for bubbly flow in vertical pipes. Sociedad Nuclear Española. http://hdl.handle.net/10251/71943

Estudio del flujo bifásico aire-líquido en tuberías verticales: Base de datos experimental para la validación de programas CFD

El estudio del comportamiento del flujo multifásico y su modelado ha sufrido un gran cambio con la introducción de los programas CFD, y el avance en los sistemas de medida. La resolución temporal y espacial de los programas de cálculo y la instrumentación se ha incrementado notablemente. Así, se hace indispensable disponer de nuevos resultados experimentales que permitan desarrollar nuevos modelos adaptados a estas capacidades, y a su vez validar las actuales herramientas de cálculo, especialmente los códigos CFD. La Universitat Jaume I de Castelló y la Universidad Politécnica de Valencia poseen una larga trayectoria en la experimentación y modelado de sistemas bifásicos. Fruto de ello se ha desarrollado en la UJI una instalación experimental, un loop vertical de 6 metros para estudiar el flujo bifásico en tuberías, con abundante instrumentación como sondas de conductividas, LDA y cámaras rápidas. En este trabajo se presentarán los resultados para tuberías verticales de 52 mm de diámetro en régimen de bubbly y slug. La instalación experimental está totalmente automatizada y es capaz de medir distribución de fracción de huecos, velocidad de la fase gas y líquido, turbulencia de la fase líquida, densidad de área interfacial y distribución de población de burbujas y tamaños. Se han desarrollado las sondas de conductividad de 4 sensores y el software para el procesado e la señal obtenida. Se han ensayado en el rango de velocidad del líquido de 0.5 a 3 m/s y fracciones de gas medias de 5 a 30%, así como con temperaturas y tensiones interraciales del fluido distintas. Se han tomado medidas en tres puertos axiales y en cada uno de ellos 15 puntos radiales. Con todo ello se ha creado una base de datos detallada que permite a los investigadores desarrollar nuevos modelos o validar los códigos actuales con garantías. En ella se estudia el flujo en régimen bubbly, la transición hacia slug y el inicio del slug. Cabe destacar el estudio realizado mediante LDA de la fase líquido , lo que permite obtener distribuciones radiales de talladas de velocidad y turbulencia.Monrós, G.; Martínez, R.; Torro, S.; Chiva Vicent, S.; Peña Monferrer, C.; Muñoz-Cobo González, JL. (2014). Estudio del flujo bifásico aire-líquido en tuberías verticales: Base de datos experimental para la validación de programas CFD. Sociedad Nuclear Española. http://hdl.handle.net/10251/71303

CFD modelling and validation of upward bubbly flow in an adiabatic vertical pipe using the quadrature method of moments

[EN] An Eulerian-Eulerian approach was investigated to model adiabatic bubbly flow with CFD techniques. In the framework of the OpenFOAM (R) software, a two-fluid model solver was modified to include a population balance equation, solved with the quadrature method of moments approximation to predict upward bubbly flow in vertical pipes considering the polydisperse nature of two-phase flow. Some progress have been made recently solving population balance equations in OpenFOAM (R) and this research aims to extend its application to the case of vertical pipes under different conditions of liquid and gas velocities. In order to test the solver for nuclear applications, interfacial forces and bubble induced turbulence models were included to provide to this solver the capability to correctly predict the behavior of the continuous and disperse phases. Two-phase flow experiments with different superficial velocities of gas and liquid are used to validate the model and its implementation. Radial profiles of void fraction, gas and liquid velocities, Sauter mean diameter and turbulence intensity are compared to the computational results. These results are in satisfactory agreement with the experiments, showing the capability of the solver to predict two-phase flow characteristics.The authors sincerely thank the "Plan Nacional de I+D+i" Projects ENE2013-48565-C2-1-P and ENE2013-48565-C2-2-P for funding the project. C. Pena-Monferrer would like to thank the Department of Mechanical Engineering at Iowa State University for hosting him while performing part of this research work.Peña Monferrer, C.; Passalacqua, A.; Chiva Vicent, S.; Muñoz-Cobo González, JL. (2016). CFD modelling and validation of upward bubbly flow in an adiabatic vertical pipe using the quadrature method of moments. Nuclear Engineering and Design. 301:320-332. https://doi.org/10.1016/j.nucengdes.2016.03.0060029-5493S32033230

An experimental study on bubble entrainment and flow characteristics of vertical plunging water jets

When a vertical liquid jet plunges into a liquid surface after passing through a surrounding gas phase it entrains a large amount of gas bubbles into the receiving pool, and forms a large submerged two-phase region with a considerable interfacial area. At the intersection of the plunging jet and the liquid surface, free-surface instabilities develop, and gas entrainment may be observed. In this study, a set of experiments were performed on plunging water jets injected vertically downward through short circular nozzles lN/dN 6 5 onto a free water surface. The effect of the operation conditions including initial jet diameters dN, initial jet velocity VN, and jet length x1 on the flow characteristics such as the inception velocity of the gas entrainment Ve, the bubble penetration depth Hp, the gas entrainment rate Qa, the centerline jet velocity Vc, and the axial jet velocity distribution Vx below the free water surface were evaluated. A flow visualization technique using a CCD camera, which allowed simultaneous measurements of several magnitudes, was used to investigate such flows. This technique provided a direct measurement of the interfacial behavior between the entrained air bubbles and the liquid ambient. The results obtained showed that the nondimensional bubble penetration depth Hp/dN decreased with the dimensionless jet length x1/dN up to 25, after this point it was almost constant. Also, the bubble penetration depth was found to increase with the jet velocity and nozzle diameters. The entrainment rate tended to increase when the jet velocity increased and its functional dependence was divided into three regions depending on the jet velocity. The value of Qa was also found to increase as x1 and dN increased for the same jet flow rate. The jet centerline velocity decay Vc was measured and found to be a function of: the jet impact velocity V1 with the plunge water surface, the jet diameter d1 and the plunge depth x. The axial velocity distributions Vx/Vc were found to be approximately Gaussian distributions for all the cases when plotted against r/bu. Empirical relationships were proposed to predict the jet parameters and when were compared with the available experimental data and correlation of other authors a good agreement was found.The authors of this paper are indebted to the National of I + D projects REMODERN ENE2010-21368-CO2-01/CON and ENE 2010-21368-CO2-02/CON.Harby Mohamed Abd Alaal, K.; Chiva Vicent, S.; Muñoz-Cobo González, JL. (2014). An experimental study on bubble entrainment and flow characteristics of vertical plunging water jets. Experimental Thermal and Fluid Science. 57:207-220. https://doi.org/10.1016/j.expthermflusci.2014.04.004S2072205

Tracking of bubble trajectories in vertical pipes in bubbly flow regime by coupling lagrangian, eulerian and 3D random walks models: Validation with experimental data

A set of air-water experiments has been performed under isothermal upward concurrent flow conditions, in a vertical column. The interfacial velocity, the bubble interfacial area and the void fraction distributions have been measured. Numerical simulation of these experiments were performed by coupling a Lagrangian code which tracks the 3D motion of the individual bubbles, with an Eulerian one. In the Eulerian solver the velocity and turbulence fields of the liquid phase were computed by solving the time dependent conservation equations in its Reynolds Averaged Transport Equation form (RANS). The turbulent kinetic energy k, and the dissipation rate transport equations were simultaneously solved by using the k, epsilon model in a (r, z) grid by the finite volume method and the SIMPLER algorithm. Both Lagrangian and Eulerian calculations were performed in parallel and an iterative self-consistent method was developed. The turbulence induced by the bubbles is an important issue considered in this paper, in order to obtain good predictions of the void fraction distribution and the interfacial velocity at different gas and liquid flow conditions. The Eulerian Code was upgraded from an axisymmetric 2D code to a 3D code in order to improve the turbulence solution. The results of the 3D CFD code have been tested and show a good agreement with the experimental results. In this paper special attention is given to the coupling between the different models.Muñoz-Cobo González, JL.; Chiva Vicent, S.; Essa, MAA.; Mendes, S. (2012). Tracking of bubble trajectories in vertical pipes in bubbly flow regime by coupling lagrangian, eulerian and 3D random walks models: Validation with experimental data. Journal of Computational Multiphase Flows. 4(3):309-326. doi:10.1260/1757-482X.4.3.309S3093264

Participación en el Benchmark MATiS-H de la NEA/OCDE: Usos de códigos CFD aplicados a seguridad nuclear. Estudio de las rejillas espaciadoras en los elementos combustibles

Nuclear fuel bundles contain spacers essentially for mechanical stability and to influence the flow dynamic and heat transfer phenomena along the fuel rods. This work presents the analysis of the turbulence effects of a split-type and swirl-type spacer grid geometries on single-phase in a PWR (Pressurized Water Reactor) rod bundle. Various Computational Fluid Dynamics (CFD) calculations have been performed and the results validated with the experiments of the OECD/NEA-KAERI Rod Bundle CFD Benchmark Exercise on Turbulent Mixing in a Rod Bundle with Spacers at the MATiS-H facility. The aim of this Benchmark is to provide validated CFD analysis tools providing a firm basis for quantifying the CHF Margin reliably for normal operation and operational transients conditions and allowing eventually the use of CMFD Codes for predicting DNB under accidental conditions [1]. Simulation of turbulent phenomena downstream of the spacer grid presents high complexity issues. A wide range of length scales are present increasing the difficulty of defining in detail the transient nature of turbulent flow. Calculations were performed with the commercial code ANSYS R CFX R and CFD modelling using Large Eddy Simulation (LES) turbulence models by comparison with measurements to determine their suitability in the prediction of the turbulence phenomena. One of the most important aspects to be taken into account in order to properly simulate the flow downstream of the spacer grids is the use of a suitable turbulence model. Time-averaged values for all three velocity components, timeaveraged RMS values of the fluctuating component of all three velocity components in several cross-planes downstream of the spacer grid and circulation data in a selected sub-channel are in good agreement with the measured data. These results could be of great value for future studies of spacer grid including heat transfer from the rods and as a basis of spacer grid simplifications.Peña Monferrer, C.; Chiva Vicent, S.; Muñoz-Cobo González, JL.; Vela, E.; Pelayo, F. (2012). Participation in the NEA/OECD MATiS-H Benchmark exercise. Study of spacer grids in a rod bundle. Sociedad Nuclear Española. http://hdl.handle.net/10251/71522

Molecular basis for the protective effects of low-density lipoprotein receptor-related protein 1 (LRP1)-derived peptides against LDL aggregation

Aggregated LDL is the first ligand reported to interact with the cluster II CR9 domain of low-density lipoprotein receptor-related protein 1 (LRP1). In particular, the C-terminal half of domain CR9, comprising the region Gly1127-Cys1140 exclusively recognizes aggregated LDL and it is crucial for aggregated LDL binding. Our aim was to study the effect of the sequence Gly1127-Cys1140 (named peptide LP3 and its retro-enantio version, named peptide DP3) on the structural characteristics of sphingomyelinase- (SMase) and phospholipase 2 (PLA2)-modified LDL particles. Turbidimetry, gel filtration chromatography (GFC) and transmission electronic microscopy (TEM) analysis showed that LP3 and DP3 peptides strongly inhibited SMase- and PLA2-induced LDL aggregation. Nondenaturing polyacrylamide gradient gel electrophoresis (GGE), agarose gel electrophoresis and high-performance thin-layer chromatography (HPTLC) indicated that LP3 and DP3 prevented SMase-induced alterations in LDL particle size, electric charge and phospholipid content, respectively, but not those induced by PLA2. Western blot analysis showed that LP3 and DP3 counteracted changes in ApoB-100 conformation induced by the two enzymes. LDL proteomics (LDL trypsin digestion followed by mass spectroscopy) and computational modeling methods evidenced that peptides preserve ApoB-100 conformation due to their electrostatic interactions with a basic region of ApoB-100. These results demonstrate that LRP1-derived peptides are protective against LDL aggregation, even in conditions of extreme lipolysis, through their capacity to bind to ApoB-100 regions critical for ApoB-100 conformational preservation. These results suggests that these LRP1(CR9) derived peptides could be promising tools to prevent LDL aggregation induced by the main proteolytic enzymes acting in the arterial intima.The Ministry of Science and Innovation of Spain, in the framework of the State Plan of Scientific and Technical Innovation Investigation 2013–2016, awarded funding to the project “DEVELOPMENT OF AN INNOVATIVE THERAPY FOR THE TREATMENT OF THE ATHEROSCLEROSIS THROUGH INHIBITION OF CHOLESTEROL VASCULAR ACCUMULATION”, led by IPROTEOS SL with file number RTC-2016-5078-1. This project was also financed by the Ministry of Economy, Industry and Competitiveness (MINECO) in the framework of the Subprogram RETOS-COLABORACIÓN, 2016 call. The project is also co-financed by the European Union with the objective to promoting the technological development, innovation and quality research. Support was also received from SAF2017-89613R (to SV), co-financed by the European Regional Development Fund (ERDF), the Fundació la Marató de TV3 Project 201521-10 (to VLlC), FIS PI13/00364 and PI16/00471 (to JSQ) and FIS PI18/01584 (to VLlC) from the Instituto de Salud Carlos III (ISCIII) and co-financed with ERDF. Support was also received from Ministerio de Economía y Competitividad to DdG-C (IJCI-2016-29393). CIBER Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM; CB07/08/0016 (JSQ) and CIBER de Enfermedades Cardiovasculares (CIBERCV; CB16/1100403 (DdG-C, VLlC) are projects run by the Instituto de Salud Carlos III (ISCIII). The CRG/UPF Proteomics Unit is member of ProteoRed PRB3 consortium which is supported by grant PT17/0019 of the PE I+D+i 2013–2016 from the Instituto de Salud Carlos III (ISCIII) and ERDF. We also acknowledge support from the Spanish Ministry of Economy and Competitiveness, “Centro de Excelencia Severo Ochoa 2013–2017”, SEV-2012-0208, and “Secretaria d'Universitats i Recerca del Departament d'Economia I Coneixement de la Generalitat de Catalunya” (2017SGR595 to ES and 2017SGR946 to VLl-C). SB, JLS-Q, AR-U, DdG-C and VL-C are members of the Group of Vascular Biology of the Spanish Society of Atherosclerosis (SEA)