Papers by Helena M. Ramos
Book - http://www.intechopen.com/books/energy-efficiency-the-innovative-ways-for-smart-energy-the-future-towards-modern-utilities/pumped-storage-and-hybrid-energy-solutions-towards-the-improvement-of-energy-efficiency-in-water-sys, 2012
Water
Urbanization and population growth have been responsible for a significant increase in consumptio... more Urbanization and population growth have been responsible for a significant increase in consumption of water and energy at a global scale. A careful management of water resource and infrastructures is crucial for Energy Transition, as well as for achieving a sustainable efficiency of these systems. High pressure values along with the ageing of the systems contribute to high leakage levels of Water Distribution Networks (WDN). The simultaneous control of excess pressure and containment of water losses are mainly performed by using Pressure Reducing Valves (PRVs) in WDN, which dissipate the surplus of hydraulic energy. Instead of being dissipated, energy can be recovered by the transformation of the excess pressure into electrical energy with the use of Pump as Turbines (PAT), which results in an increased reliability, reduction of cost and an overall improvement in the efficiency of WDN. The work aims on presenting an integrated efficiency management methodology in terms of Effectiven...
Water
One of the main factors contributing to water scarcity is water loss in water distribution system... more One of the main factors contributing to water scarcity is water loss in water distribution systems, which mainly arises from a lack of adequate knowledge in the design process, optimization of water availability, and poor maintenance/management of the system. Thus, from the perspective of sustainable and integrated management of water resources, it is essential to enhance system efficiency by monitoring existing system elements and enhancing network maintenance/management practices. The current study establishes a smart water grid (SWG) with a digital twin (DT) for a water infrastructure to improve monitoring, management, and system efficiency. Such a tool allows live monitoring of system components, which can analyze different scenarios and variables, such as pressures, operating devices, regulation of different valves, and head-loss factors. The current study explores a case study in which local constraints amplify significant water losses. It develops and examines the DT model’s ...
Energies
A review of different energy components is detailed, as a baseline of fundamentals for the new in... more A review of different energy components is detailed, as a baseline of fundamentals for the new integrated energy concept idealization. This innovative solution is a Hybrid for Renewable Energy Network (Hy4REN) based on well-studied elements to produce the best final solution. This proposal has the objective of improving energy system sustainability, facing fossil fuel and climate change restrictions, and increasing energy network flexibility. The most mature energy storage technology, pumped hydropower energy storage (PHES), is used to support both the grid connection and stand-alone modes, as an integrated hybrid energy system. The hybrid system idealization is modular and scalable, with a complementary nature among several renewables, using sea water in offshore mode to build an integrated solution. By evaluating a variety of energy sources, complemented with economic analysis, the benefits associated are evidenced using this sustainable methodology based only on renewable sources...
Water
This research proposes a methodology with multi-objective optimization for the placement of Pumps... more This research proposes a methodology with multi-objective optimization for the placement of Pumps operating As Turbines (PATs), energizing street lighting, devices for monitoring the water network, and charging stations for small electric vehicles such as bikes and scooters. This methodology helps to find the most profitable project for benefiting life quality and energy recovery through pumps operating as turbines, replacing virtual pressure reduction valves to locate the best point for decreasing pressure. PATs are selected by maximizing power recovery and minimizing pressure in the system as well as maximizing recoverable energy. Benefits analyzed include the reduction of carbon dioxide emissions and fuel use, as well as the saving of electricity consumption and benefiting socio-economic impact with street lighting, monitoring, and charging station. It was considered that each PAT proposed by the methodology will supply a street light pole, a station for monitoring the water netw...
Fluids
The open source and freely available fluid flow solver named caffa3d was adapted to simulate the ... more The open source and freely available fluid flow solver named caffa3d was adapted to simulate the performance of a medium-scale Hydrostatic Pressure Machine (HPM) with straight radial blades, which had been previously tested in a laboratory facility. A fully detailed explanation of the code caffa3d is not intended to be included in this paper, but some of its main characteristics are mentioned for completeness. In addition, convergence and grid sensitivity analysis were performed in order to assess the adequacy of the model. Evolution of instantaneous power over a few turns of the HPM shows typical blade pass frequency for all operating discharges and another oscillatory phenomena at rotating frequency for higher discharges. The Power—Discharge and Efficiency—Discharge curves obtained from the simulations present a good correlation with the experimental curves, up to the discharge value corresponding to the maximum power of the HPM. The comparison error in power and efficiency remain...
Water
Hydraulic turbines for energy recovery in wastewater treatment plants, with relatively large disc... more Hydraulic turbines for energy recovery in wastewater treatment plants, with relatively large discharges values and small head jumps, are usually screw Archimedes or Kaplan types. In the specific case of a small head jump (about 3 m) underlying a rectangular weir in the major Palermo (Italy) water treatment plant, a traditional Kaplan solution is compared with two other new proposals: a Hydrostatic Pressure Machine (HPM) located at the upstream channel and a cross-flow turbine (CFT) located in a specific underground room downstream of the same channel. The fluid mechanical formulations of the flow through these turbines are analyzed and the characteristic parameters are stated. Numerical analysis was carried out for the validation of the HPM design criteria. The efficiency at the design point of the CFT and HPM are estimated using the ANSYS CFX solver for resolution of 3D URANS analysis. The strong and weak points of the three devices are compared. Finally, a viability analysis is de...
Colección Manual de referencia, Sep 4, 2020
miento como bomba. Esta manera de operar conlleva incertidumbres propias de métodos semiempíricos... more miento como bomba. Esta manera de operar conlleva incertidumbres propias de métodos semiempíricos que serán presentados en capítulos posteriores. El presente capítulo describe un análisis de la conveniencia de la utilización de las bombas en modo turbinas, la motivación de su uso y la historia de su aplicación a partir de la literatura especializada en los diversos aspectos energéticos relacionados con su uso en las redes de distribución de agua a presión. Palabras clave: análisis energético en redes de distribución a presión; bombas funcionando como turbinas: historia de uso.
Fluids, 2020
The capability of two different OpenFOAM® solvers, namely interFoam and twoPhaseEulerFoam, in rep... more The capability of two different OpenFOAM® solvers, namely interFoam and twoPhaseEulerFoam, in reproducing the behavior of a free water jet was investigated. Numerical simulations were performed in order to obtain the velocity and air concentration profiles along the jet. The turbulence intensity was also analyzed. The obtained results were compared with published experimental data and, in general, similar velocity and air concentration profiles were found. InterFoam solver is able to reproduce the velocity field of the free jet but has limitations in the simulation of the air concentration. TwoPhaseEulerFoam performs better in reproducing the air concentration along the jet, the results being in agreement with the experimental data, although the computational runs are less stable and more time consuming. The sensitivity analysis of the inlet turbulent intensity showed that it has no influence in the characteristics of the jet core. With this research it is possible to conclude that:...
Water, 2020
The Hydrostatic Pressure Machine (HPM) is a novel energy converter for micro and pico hydropower ... more The Hydrostatic Pressure Machine (HPM) is a novel energy converter for micro and pico hydropower that becomes very suitable for installation in channels with very low head, where conventional hydraulic turbines are inadequate or too expensive. Although this technology has been studied through several experimental tests and also by numerical simulations, open source flow solvers have not been used yet. The research team on Computational Fluid Mechanics of IMFIA- Universidad de la República (Uruguay) has been developing a CFD open source solver named caffa3d, which has obtained great results in a few international challenges, although it has not been used yet for free surface flows or turbomachinery simulations. The present work shows the contributions made within caffa3d in order to enable its use for simulating a HPM. The Large Eddy Simulation (LES) method is used to model the turbulence structures of the flow. Sliding Mesh (SM) and Volume of Fluid (VOF) methods were chosen respecti...
Water, 2018
Water distribution networks (WDNs) are designed to meet water demand with minimum implementation ... more Water distribution networks (WDNs) are designed to meet water demand with minimum implementation costs. However, this approach leads to poor long-term results, since system resilience is also minimal, and this requires the rehabilitation of the network if the network is expanded or the demand increases. In addition, in emergency situations, such as pipe bursts, large areas will suffer water shortage. However, the use of resilience as a criterion for WDN design is a difficult task, since its economic value is subjective. Thus, in this paper, it is proposed that trunk networks (TNs) are rehabilitated when considering the generation of electrical energy using pumps as turbines (PATs) to compensate for an increase of resilience derived from increasing pipe diameters. During normal operation, these micro-hydros will control pressure and produce electricity. When an emergency occurs, a bypass can be used to increase network pressure. The results that were obtained for two hypothetical networks show that a small increase in TN pipe diameters is sufficient to significantly improve the resilience of the WDN. In addition, the value of the energy produced surpasses the investment that is made during rehabilitation.
"Water Supply System Analysis - Selected Topics", book edited by Avi Ostfeld, ISBN 978-953-51-0889-4, Published: December 12, 2012 under CC BY 3.0 license, 2012
Linköping Electronic Conference Proceedings, 2011
This work focuses on the analysis of the power generation feasibility of both a pump as turbine (... more This work focuses on the analysis of the power generation feasibility of both a pump as turbine (PAT) and an experimental propeller turbine, when applied to water supply systems. This is done through an analysis of the electrical generation aspects of the PAT's induction motor and of a permanent magnet DC motor, which was connected to the propeller turbine. The collected data allows for parameter optimization, adequate generator choice and computational modeling. These tests constitute a good sample of the range of applicability of small scale turbines as valid solutions for micro-hydro. It is also possible to consider multiple scenarios, such as rescaling/resizing, for larger turbines and systems, and the use of power electronics for further efficiency enhancing.
Journal of Energy, 2013
The majority of the life cycle costs (LCC) of a pump are related to the energy spent in pumping, ... more The majority of the life cycle costs (LCC) of a pump are related to the energy spent in pumping, with the rest being related to the purchase and maintenance of the equipment. Any optimizations in the energy efficiency of the pumps result in a considerable reduction of the total operational cost. The Fátima water supply system in Portugal was analyzed in order to minimize its operational energy costs. Different pump characteristic curves were analyzed and modeled in order to achieve the most efficient operation point. To determine the best daily pumping operational scheduling pattern, genetic algorithm (GA) optimization embedded in the modeling software was considered in contrast with a manual override (MO) approach. The main goal was to determine which pumps and what daily scheduling allowed the best economical solution. At the end of the analysis it was possible to reduce the original daily energy costs by 43.7%. This was achieved by introducing more appropriate pumps and by intell...
The present work comprises a research about hydraulic machines with the aim of optimization and t... more The present work comprises a research about hydraulic machines with the aim of optimization and the selection of adequate turbines of low power for exploitation of an available energy still unexplored in water supply systems based on analyses of 3D hydrodynamic flows and on characteristic curves which lead to the best efficiency point. The analysis is carried out based on non-dimensional parameters (i.e., discharge, head, efficiency, runner speed and mechanical power) in order to be possible comparisons. Mathematical models based on the physical principles, associated to the development of volumetric and rotordynamic machines, are developed. New turbines are suggested, which are based on similar theory among turbo machines based on applications in hydraulic systems with guarantee discharge and available head. The hydrodynamic fluid mechanical analysis requires the use of complex advanced models (CFD) which apply the equations of Navier-Stokes by using mathematical models of conservation laws, for the study of the turbulent flow behaviour. To determine the correlation between the flow velocity and pressure fields, the k-ε model, is used in this research. Many turbines are evaluated (i.e., positive displacement (PD), pump as turbine (PAT), propeller with volute at inlet, four and five blades tubular propellers) and sensitivity analyses, to the best configurations, as well as comparisons between performance curves and experimental tests. Results are presented with the appropriate range variation for each turbine type and application.
Water Supply, 2004
The current paper reports the investigation of two transient-based techniques for leak detection ... more The current paper reports the investigation of two transient-based techniques for leak detection in water pipe systems using physical data collected in the laboratory and in quasi-field conditions. The first is the analysis of the leak reflected wave during a transient event and the second is inverse transient analysis (ITA). This was approached through the development of an inverse transient analysis tool and the collection of transient data for the testing and validation of this model. Two experimental programmes were carried out at Imperial College and in cooperation with Thames Water for the validation and testing of these techniques. Evaluation of the presence, location and size of leaks was carried out using the collected data. Transient-based techniques have been shown to be successful in the detection and location of leaks and leak location uncertainties depended on the leak size and location, flow regime and location where the transient event was generated. These leak detec...
Energies, 2022
Water distribution networks need to improve system efficiency. Hydropower is a clean and renewabl... more Water distribution networks need to improve system efficiency. Hydropower is a clean and renewable energy that has been among the key solutions to environmental issues for many decades. As the turbine is the core of hydropower plants, high attention is paid to creating new design solutions and increasing the performance of turbines in order to enhance energy efficiency of leakage by pressure control. Hence, design and performance analysis of a new turbine is a crucial aspect for addressing the efficiency of its application. In this study, computational fluid dynamics (CFD) modeling is coupled with experimental tests in order to investigate the optimal performance of a new centrifugal turbine. The behavior of the flow through the turbine runner is assessed by means of velocity profiles and pressure contours at all components of the machine under different operating conditions. Finally, the turbine geometry is scaled to a real water distribution network and an optimization procedure i...
Pumps as Turbines, 2017
Information about the different components of a PAT and an overall description of civil engineeri... more Information about the different components of a PAT and an overall description of civil engineering design are presented. The electromechanical transmission arrangements realized to avoid dissipative effects and to guarantee the best operating conditions are defined and additional aspects associated with installation procedures and operation and maintenance are described. A theoretical and project-based design for the comprehension of a micro-hydropower scheme connected with a PAT installation in water systems is presented. Different design components and the rules to be followed by engineering designers are defined. A PAT-based micro-hydropower plant includes civil engineering and electromechanical aspects, the latter consisting in mechanical and electrical equipment. In addition to civil engineering work, mechanical and electrical components are required in a PAT, as well as a generator, control system and electricity transfer. The PAT body belongs to the class of mechanical components but the generator and control system are electromechanical systems. While a hydropower plant is a chain operation from the water intake to the electricity consumer, an overview of its components is very useful in terms of the design, selection and operation. The installation and operation of micro-hydro solutions can improve energy efficiency through electricity generation and simultaneously in the pressure control of water systems, particularly in cities with considerable geodesic differences, or in irrigation areas, drainage systems and pipelines, and in pipe sections where the pressure is higher than an adequate or necessary level. 6.1 Civil Engineering Design The civil works include several components: (i) the water intake and PAT inlet; (ii) the conveyance system or hydraulic circuit; and (iii) the powerhouse and machine outlet. For micro-hydro stations (MHS), the civil works are reduced and relatively straightforward since the layout schemes are, basically, characterized by
In small hydropower plants the hydraulic conveyance system and the turbine discharge control syst... more In small hydropower plants the hydraulic conveyance system and the turbine discharge control system could be relevant factors in the civil engineering design. The computational advances in hydraulic analysis and in modelling must be transformed in practical tools for engineering design, in particular, when applied to analyse small hydroelectric power plants with long hydraulic circuits. An integrated modelling system was developed by the authors, based on the interaction of different components, that enables to know the dynamic response and the definition of the more adequate methods of control rules. The case of reaction turbines (e.g. Francis) with low specific speed are especially relevant due to the fast transient overpressures caused by overspeed.
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Papers by Helena M. Ramos