Transient phenomena during the emptying process of a single pipe with water air interaction

[EN] Emptying pipelines can be critical in many water distribution networks because subatmospheric pressure troughs could cause considerable damage to the system due to the expansion of entrapped air. Researchers have given relatively little attention to emptying processes compared to filling processes. The intricacy of computations of this phenomenon makes it difficult to predict the behaviour during emptying, and there are only a few reliable models in the literature. In this work, a computational model for simulating the transient phenomena in single pipes is proposed, and was validated using experimental results. The proposed model is based on a rigid column to analyse water movement, the air¿water interface, and air pocket equations. Two practical cases were used to validate the model: (1) a single pipe with the upstream end closed, and (2) a single pipe with an air valve installed on the upstream end. The results show how the model accurately predicts the experimental data, including the pressure oscillation patterns and subatmospheric pressure troughs.This study was supported by the Program Fondecyt Regular [Project 1180660] of the Comision Nacional de Investigacion Cientifica y Tecnologica (Conicyt), Chile, http://data.crossref.org/fundingdata/funder/10.13039/501100002848.Fuertes-Miquel, VS.; Coronado-Hernández, OE.; Iglesias Rey, PL.; Mora Melia, D. (2019). Transient phenomena during the emptying process of a single pipe with water air interaction. Journal of Hydraulic Research. 57(3):318-326. https://doi.org/10.1080/00221686.2018.1492465S318326573Bashiri-Atrabi, H., & Hosoda, T. (2015). The motion of entrapped air cavities in inclined ducts. Journal of Hydraulic Research, 53(6), 814-819. doi:10.1080/00221686.2015.1060272Cabrera, E., Abreu, J., Pérez, R., & Vela, A. (1992). Influence of Liquid Length Variation in Hydraulic Transients. Journal of Hydraulic Engineering, 118(12), 1639-1650. doi:10.1061/(asce)0733-9429(1992)118:12(1639)Coronado-Hernández, O. E., Fuertes-Miquel, V. S., Iglesias-Rey, P. L., & Martínez-Solano, F. J. (2018). Rigid Water Column Model for Simulating the Emptying Process in a Pipeline Using Pressurized Air. Journal of Hydraulic Engineering, 144(4), 06018004. doi:10.1061/(asce)hy.1943-7900.0001446Fuertes-Miquel, V. S., López-Jiménez, P. A., Martínez-Solano, F. J., & López-Patiño, G. (2016). Numerical modelling of pipelines with air pockets and air valves. Canadian Journal of Civil Engineering, 43(12), 1052-1061. doi:10.1139/cjce-2016-0209Guinot, V. (2001). The discontinuous profile method for simulating two-phase flow in pipes using the single component approximation. International Journal for Numerical Methods in Fluids, 37(3), 341-359. doi:10.1002/fld.177Hou, Q., Tijsseling, A. S., Laanearu, J., Annus, I., Koppel, T., Bergant, A., … van ’t Westende, J. M. C. (2014). Experimental Investigation on Rapid Filling of a Large-Scale Pipeline. Journal of Hydraulic Engineering, 140(11), 04014053. doi:10.1061/(asce)hy.1943-7900.0000914Izquierdo, J., Fuertes, V. S., Cabrera, E., Iglesias, P. L., & Garcia-Serra, J. (1999). Pipeline start-up with entrapped air. Journal of Hydraulic Research, 37(5), 579-590. doi:10.1080/00221689909498518Laanearu, J., Annus, I., Koppel, T., Bergant, A., Vučković, S., Hou, Q., … van’t Westende, J. M. C. (2012). Emptying of Large-Scale Pipeline by Pressurized Air. Journal of Hydraulic Engineering, 138(12), 1090-1100. doi:10.1061/(asce)hy.1943-7900.0000631Leon, A. S., Ghidaoui, M. S., Schmidt, A. R., & Garcia, M. H. (2010). A robust two-equation model for transient-mixed flows. Journal of Hydraulic Research, 48(1), 44-56. doi:10.1080/00221680903565911Liou, C. P., & Hunt, W. A. (1996). Filling of Pipelines with Undulating Elevation Profiles. Journal of Hydraulic Engineering, 122(10), 534-539. doi:10.1061/(asce)0733-9429(1996)122:10(534)Liu, D., Zhou, L., Karney, B., Zhang, Q., & Ou, C. (2011). Rigid-plug elastic-water model for transient pipe flow with entrapped air pocket. Journal of Hydraulic Research, 49(6), 799-803. doi:10.1080/00221686.2011.621740Malekpour, A., & Karney, B. (2014). Column separation and rejoinder during rapid pipeline filling induced by a partial flow blockage. Journal of Hydraulic Research, 52(5), 693-704. doi:10.1080/00221686.2014.905502Martins, S. C., Ramos, H. M., & Almeida, A. B. (2015). Conceptual analogy for modelling entrapped air action in hydraulic systems. Journal of Hydraulic Research, 53(5), 678-686. doi:10.1080/00221686.2015.1077353Pozos, O., Gonzalez, C. A., Giesecke, J., Marx, W., & Rodal, E. A. (2010). Air entrapped in gravity pipeline systems. Journal of Hydraulic Research, 48(3), 338-347. doi:10.1080/00221686.2010.481839Tijsseling, A. S., Hou, Q., Bozkuş, Z., & Laanearu, J. (2015). Improved One-Dimensional Models for Rapid Emptying and Filling of Pipelines. Journal of Pressure Vessel Technology, 138(3). doi:10.1115/1.4031508Wang, K.-H., Shen, Q., & Zhang, B. (2003). Modeling propagation of pressure surges with the formation of an air pocket in pipelines. Computers & Fluids, 32(9), 1179-1194. doi:10.1016/s0045-7930(02)00103-2Wang, H., Zhou, L., Liu, D., Karney, B., Wang, P., Xia, L., … Xu, C. (2016). CFD Approach for Column Separation in Water Pipelines. Journal of Hydraulic Engineering, 142(10), 04016036. doi:10.1061/(asce)hy.1943-7900.0001171Zhou, L., & Liu, D. (2013). Experimental investigation of entrapped air pocket in a partially full water pipe. Journal of Hydraulic Research, 51(4), 469-474. doi:10.1080/00221686.2013.785985Zhou, L., Liu, D., & Karney, B. (2013). Investigation of Hydraulic Transients of Two Entrapped Air Pockets in a Water Pipeline. Journal of Hydraulic Engineering, 139(9), 949-959. doi:10.1061/(asce)hy.1943-7900.0000750Zhou, L., Liu, D., Karney, B., & Wang, P. (2013). Phenomenon of White Mist in Pipelines Rapidly Filling with Water with Entrapped Air Pockets. Journal of Hydraulic Engineering, 139(10), 1041-1051. doi:10.1061/(asce)hy.1943-7900.000076

Caracterización de válvulas de admisión y expulsión de aire comerciales

El objetivo del trabajo es estudiar en detalle el comportamiento real de diferentes ventosas (válvulas de admisión y expulsión de aire). La primera parte del trabajo describe las diferentes técnicas experimentales de caracterización de ventosas. En la segunda parte se utiliza el banco de pruebas de válvulas de aire construido por Bermad CS en su fábrica de Evron, Israel, para realizar los ensayos de caracterización estática a diferentes ventosas comerciales. Finalmente se realiza un estudio comparativo del comportamiento de los diferentes modelos analizados, analizando los coeficientes más adecuados para la caracterización matemática de estos elementos

Validation of Calprotectin As a Novel Biomarker For The Diagnosis of Pleural Effusion: a Multicentre Trial

Discriminating between malignant pleural effusion (MPE) and benign pleural effusion (BPE) remains difficult. Thus, novel and efficient biomarkers are required for the diagnosis of pleural effusion (PE). The aim of this study was to validate calprotectin as a diagnostic biomarker of PE in clinical settings. A total of 425 patients were recruited, and the pleural fluid samples collected had BPE in 223 cases (53.7%) or MPE in 137 patients (33%). The samples were all analysed following the same previously validated clinical laboratory protocols and methodology. Calprotectin levels ranged from 772.48 to 3,163.8 ng/mL (median: 1,939 ng/mL) in MPE, and 3,216-24,000 ng/mL in BPE (median: 9,209 ng/mL; p < 0.01), with an area under the curve of 0.848 [95% CI: 0.810-0.886]. For a cut-off value of </= 6,233.2 ng/mL, we found 96% sensitivity and 60% specificity, with a negative and positive predictive value, and negative and positive likelihood ratios of 96%, 57%, 0.06, and 2.4, respectively. Multivariate analysis showed that low calprotectin levels was a better discriminator of PE than any other variable [OR 28.76 (p < 0.0001)]. Our results confirm that calprotectin is a new and useful diagnostic biomarker in patients with PE of uncertain aetiology which has potential applications in clinical practice because it may be a good complement to cytological methods

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Improving water quality by means of programmed flushing in the drinking water network of Valencia (Spain)

[EN] Access to an adequate quantity and quality of drinking water is one of the rights recognized by the United Nations (UN) and the World Health Organization (WHO). In fact, it is explicitly outlined in Sustainable Development Goal 6 (SDG 6), Clean Water and Sanitation. While in the European Union, this goal is considered achieved, there have been issues related to water quality. The implementation of pressure management strategies to control leakages by defining district metering areas leads to dead-end branches where water can remain stagnant for a long time with minimal movement. Large residence times of water in these areas contribute to the decay of disinfectants, the formation of disinfection by-products, and the growth of biofilm. Under these conditions, branches are more susceptible to non-compliance with water quality monitoring. In addition to disinfection treatments applied in plants, there are other strategies to improve the quality of drinking water at consumption points, which will be studied in this work. One of these strategies is the use of water flushing that allow renewal of water at stagnation points. These flushes involve water loss which, in a water-deficient country such as Spain, must be minimized. This study compares three methods to determine the minimum volume of flushed water needed to maintain a quality target at acceptable levels. The results show that the combination of a traditional method based on the improvement gradient, combined with a heuristic method such as Simulated Annealing, can be a good option to achieve this goal.[ES] El acceso al agua potable en cantidad y calidad aceptable es uno de los derechos reconocidos por la ONU y la OMS. De hecho, está explícitamente recogido en el Objetivo de Desarrollo Sostenible ODS 6, Agua Limpia y Saneamiento. Si bien en la Unión Europea este objetivo se considera alcanzado, en algunos casos ha habido problemas relacionados con la calidad del agua. La implantación de sistema de control de fugas mediante la sectorización trae como consecuencia la aparición de ramales sin salida en los que el agua puede permanecer largo tiempo sin apenas movimiento. Los altos tiempos de residencia del agua en estas zonas favorece la desaparición del desinfectante, la formación de subproductos de la desinfección y el crecimiento de biopelícula. En estas condiciones, los ramales son más susceptibles al incumplimiento en los monitoreos de calidad de agua. Aparte de los tratamientos de desinfección aplicados en las plantas, hay otras estrategias que permiten mejorar la calidad del agua potable en los puntos de consumo, las cuales se van a estudiar en el presente trabajo. Una de estas estrategias es la utilización de purgas controladas de agua que permitan la renovación en los puntos de estancamiento. Estas purgas implican una pérdida de agua que, en un país con déficit como es el caso español, deben reducirse al máximo. En este trabajo se comparan tres métodos para determinar el volumen mínimo de agua de purga necesario para mantener un objetivo de calidad en niveles aceptables. Los resultados muestran que la combinación de un método tradicional basado en el gradiente de mejora, combinado con un método heurístico como es el Simulated Annealing puede ser una buena opción para alcanzar este objetivo.Este trabajo ha sido realizado en el marco del Convenio 689345 de prácticas en la empresa Global Omnium financiadas por la Cátedra Aguas de Valencia y realizadas en la Universidad Politécnica de Valencia.Olortegui-Artica, C.; Martínez-Solano, FJ.; Sánchez-Briones, C.; Iglesias-Rey, PL. (2024). Uso de las purgas programadas como herramienta para la mejora de la calidad del agua en la red de agua potable de la ciudad de Valencia. Ingeniería del Agua. 28(2):106-122. https://doi.org/10.4995/ia.2024.2090810612228

Infeasibility Maps: Application to the Optimization of the Design of Pumping Stations in Water Distribution Networks

The design of pumping stations in a water distribution network determines the investment costs and affects a large part of the operating costs of the network. In recent years, it was shown that it is possible to use flow distribution to optimize both costs concurrently; however, the methodologies proposed in the literature are not applicable to real-sized networks. In these cases, the space of solutions is huge, a small number of feasible solutions exists, and each evaluation of the objective function implies significant computational effort. To avoid this gap, a new method was proposed to reduce the search space in the problem of pumping station design. This method was based on network preprocessing to determine in advance the maximum and minimum flow that each pump station could provide. According to this purpose, the area of infeasibility is limited by ranges of the decision variable where it is impossible to meet the hydraulic constraints of the model. This area of infeasibility is removed from the search space with which the algorithm works. To demonstrate the benefits of using the new technique, a new real-sized case study was presented, and a pseudo-genetic algorithm (PGA) was implemented to resolve the optimization model. Finally, the results show great improvement in PGA performance, both in terms of the speed of convergence and quality of the solution

Utilización de las ventosas para la expulsión del aire durante el llenado de las tuberías. Comportamiento adiabático frente a isotermo

Las conducciones con perfil irregular presentan una serie de particularidades que no pueden ser ignoradas, como puede ser la posible acumulación de bolsas de aire en los puntos altos. Para evitar los problemas derivados de esta situación se recurre a la instalación de ventosas (también llamadas válvulas de aire), las cuales permiten la entrada y salida de aire. Pero el aire introducido en la conducción debe ser expulsado y ello debe hacerse de forma adecuada para evitar sobrepresiones indeseables. El aire atrapado entre dos columnas de agua en una conducción a presión, con o sin ventosas, puede provocar importantes picos de presión cuando se arranca la instalación. En el presente trabajo se pretende estudiar y modelar el problema del llenado de tuberías con aire atrapado y ventosas instaladas en los puntos altos, para poder predecir el transitorio que se producirá y tratar de evaluar los peligrosos picos de presión que pudieran generarse. Se utiliza el modelo rígido para analizar el comportamiento de n bolsas de aire atrapado en tuberías de perfil irregular con vi ventosas instaladas. También se revisan las condiciones de contorno de las ventosas en su fase más crítica, la de expulsión de aire. El comportamiento isotermo del aire atrapado, tal cual se propone en los textos estándar, se compara con el comportamiento adiabático que, sin duda, es una hipótesis mucho más realista en el supuesto de transitorios muy rápidos