Helena M. Ramos

Helena M. Ramos
University of Lisbon | UL · Civil Engineering

Professor

About

250
Publications
86,610
Reads
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5,353
Citations
Introduction
Helena Margarida Ramos got her MSc degree in 1987, the PhD degree in 1995, the Habilitation degree in 2005 and she is Associate Professor at Instituto Superior Técnico (University of Lisbon). She has been professor at IST in 15 different courses. She has more than 400 publications, with 7 published books, 182 international scientific papers in journals with referee, 156 scientific papers in international conferences. She participated in 17 national and 15 international.

Publications

Publications (250)
Conference Paper
Air is present in pressurized water systems for a variety of reasons, including incomplete removal during filling, air entrainment at intakes or entrances, air admission during draining operations, or air exchanges due to transient events such as power failure or pipe burst. Each of these sources or events creates specific design and operational ch...
Article
Full-text available
The recovery of excess energy in water supply networks has been a topic of paramount importance in recent literature. In pressurized systems, a pump used in inverse mode (Pump As Turbine, PAT) demonstrated to be a very economical and reliable solution, compared to traditional energy production devices (EPDs). Due to the large variability of flow ra...
Article
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Nowadays, in the management of water distribution networks (WDNs), particular attention is paid to digital transition and the improvement of the energy efficiency of these systems. New technologies have been developed in the recent years and their implementation can be crucial to achieve a sustainable level of water networks, namely, in water and e...
Article
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The sizing of air valves during the air expulsion phase in rapid filling processes is crucial for design purposes. Mathematical models have been developed to simulate the behaviour of air valves during filling processes for air expulsion, utilising 1D and 2D schemes. These transient events involve the presence of two fluids with different propertie...
Article
Water distribution networks have high values of energy consumption from the source to the distribution. The use of pumps working as turbines is an innovative technology for leverage the energy excess in consumption nodes. The research proposes a new methodology, which couples the energy generation with other energy-consumption systems. The main goa...
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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 enha...
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Urban drainage systems are in transition from functioning simply as a transport system to becoming an important element of urban flood protection measures providing considerable influence on urban infrastructure sustainability. Rapid urbanization combined with the implications of climate change is one of the major emerging challenges. The increased...
Data
To listen-see this webinar please use this link: https://water-4.sciforum.net/ The complete webinar was recorded and published online in Youtube channel.
Article
The use of pumps working as turbines (PATs) is a sustainable technical measure that contributes to the improvement of energy efficiency in water systems. However, its performance analysis in off-grid recovery systems is a complex task that must consider both hydraulic (PAT) and electrical machines (typically a self-excited induction generator-SEIG). A...
Article
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Chlorine demand as a disinfectant for water utility impacts on unintended energy consumption from electrolysis manufacture; thus, diminishing the chlorine consumption also reduces the environmental impact and energy consumption. Problems of disinfectant distribution and uniformity in Water Distribution Networks (WDN) are associated with the exponen...
Article
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Most renewable energy (RE) studies focus on technology readiness, environmental benefits and/or cost savings. The market permeation, viability and adoption of RE technologies such as micro hydropower (MHP), however, require the alignment of other interrelated factors, such as the socio-technical, institutional and political dimensions. This is part...
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Water management and energy recovery can improve a system’s sustainability and efficiency in a cost-effective solution. This research assesses the renewable energy sources used in the water sector, as well as the related water sector performance indicators within Portuguese water management systems. A deep analysis of 432 water entities in Portugal...
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Sustainability and efficiency in irrigation are essential in the management of the water–energy–food nexus to reach the Sustainable Development Goals in 2030. In irrigation systems, the reduction of energy consumption is required to improve the system efficiency and consequently the sustainability indicators of the water network. The use of pumps w...
Article
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Studies have shown micro-hydropower (MHP) opportunities for energy recovery and CO2 reductions in the water sector. This paper conducts a large-scale assessment of this potential using a dataset amassed across six EU countries (Ireland, Northern Ireland, Scotland, Wales, Spain, and Portugal) for the drinking water, irrigation, and wastewater sector...
Article
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p>Os sistemas de abastecimento, distribuição e drenagem do setor da água são um dos principais tipos de sistemas hidráulicos artificiais com potencial para a instalação de micro-hídricas. Apesar de existirem algumas aplicações de mini-hidroeletricidade nas condutas de adução, as redes de distribuição de águas urbanas e de rega continuam a ser pouco...
Article
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Current and future smart cities are moving towards the zero-net energy use concept. To this end, the built environment should also be designed for efficient energy use and play a significant role in the production of such energy. At present, this is achieved by focusing on energy demand in buildings and to the renewable trade-off related to smart p...
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Environmental hydraulics research includes the different domains of hydrodynamics, such as the investigation and implementation of the physical and experimental applications, and research into the quantity, quality, modelling and simulation of the attributes associated with flowing water. This topic is studied both from a technical and environmenta...
Article
Full-text available
The use of pumps working as turbines (PATs) is a sustainable technical measure that contributes to the improvement of energy efficiency in water systems. However, its performance analysis in off-grid recovery systems is a complex task that must consider both hydraulic (PAT) and electrical machines (typically a self-excited induction generator-SEIG)...
Article
Full-text available
This study presents a technique based on a multi-criteria evaluation, for a sustainable technical solution based on renewable sources integration. It explores the combined production of hydro, solar and wind, for the best challenge of energy storage flexibility, reliability and sustainability. Mathematical simulations of hybrid solutions are develo...
Article
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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 simulat...
Article
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New challenges in water systems include different approaches from analysis of failures and risk assessment to system efficiency improvements and new innovative designs. In water distribution networks (WDNs), the risk function is a measure of its vulnerability level and security loss. Analyses of transient flows which are associated with the most da...
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Energy and climate change are thoroughly linked since fossil energy generation highly affects the environment, and climate change influences the renewable energy generation capacity. Hence, this study gives a new contribution to the energy generation in water infrastructures by means of an inline pumped-storage hydro (IPSH) solution. The selection...
Article
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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...
Article
A crescente crise energética e o consumo excessivo de recursos levantam a preocupação de encontrar novas fontes alternativas de energia, viabilizando novos métodos de produção e/ou tornando mais eficientes os que já existem. Pretende-se investigar a viabilidade do aproveitamento de energia em excesso em sistemas de abastecimento de água, de drenage...
Article
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The optimal and sustainable management of water distribution systems still represent an arduous task. In many instances, especially in aging water net-works, pressure management is imperative for reducing breakages and leakages. Therefore, optimal District Metered Areas represent an effective solution to decreasing the overall energy input without...
Article
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In recent years, interest has increased in new renewable energy solutions for climate change mitigation and increasing the efficiency and sustainability of water systems. Hydropower still has the biggest share due to its compatibility, reliability and flexibility. This study presents one such technology recently examined at Instituto Superior Técni...
Article
Full-text available
The use of pumps working as turbines (PATs) to improve the energy efficiency of water networks has been studied in the last years. This recovery system is justified due to a low investment contrasting with the capacity to take advantage in certain points with low and medium recoverable heads. Analyses of water systems using simulation software and/...
Chapter
Water supply systems are one of the main hydraulic systems with significant potential for installation of micro-hydropower solutions. Although there are already some mini-hydropower applications in the water sector, there is still a huge potential that continue to be under-exploited. Micro-hydro systems can be used as promising new source of renewa...
Article
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Water management towards smart cities is an issue increasingly appreciated under financial and environmental sustainability focus in any water sector. The main objective of this research is to disclose the technological breakthroughs associated with water and energy use. A methodology is proposed and applied in a case study to analyze the benefits...
Article
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The filling process in water pipelines produces pressure surges caused by the compression of air pockets. In this sense, air valves should be appropriately designed to expel sufficient air to avoid pipeline failure. Recent studies concerning filling maneuvers have been addressed without considering the behavior of air valves. This work shows a math...
Article
Water distribution networks and irrigation systems consume high energy quantities that need to be recovered if the water managers want to meet sustainable systems. A sustainability optimization is proposed in this research in order to replace the energy consumption in a golf-course system by renewable solutions joining energy recovery, sustainable...
Article
The occurrence of sub-atmospheric pressure in the drainage of pipelines containing an air pocket has been known as a major cause of several serious problems. Accordingly, some system malfunction and pipe buckling events have been reported in the literature. This case has been studied experimentally and numerically in the current research considerin...
Article
Full-text available
Water supply systems are one of the main hydraulic systems with significant potential for the installation of micro-hydropower devices. Although there are already some mini-hydropower applications in water supply systems, it is still a huge potential that continues to be under-exploited. The arrangement based on an axial turbine, such as an inline...
Article
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The rapid deployment of renewable energy technologies continues, yet the environmental impacts associated with their construction is accepted without sustainable design considerations. This life cycle assessment study quantifies the embodied burdens in the construction phase of eleven micro-hydropower installations, ranging from 70–100 kW in size....
Article
Pumps as Turbines (PATs) are standard water pumps utilized as hydraulic turbines by reversing the flow direction across them. The off-the-shelf availability of water pumps and their reduced purchase price with respect to conventional hydro turbines makes them an ideal technology for exploiting large portions of uncapped hydro potential that is tech...
Article
Full-text available
Micro-hydro systems can be used as a promising new source of renewable energy generation, requiring a low investment cost of hydraulic, mechanical, and electrical equipment. The improvement of the water management associated with the use of pumps working as turbines (PATs) is a real advantage when the availability of these machines is considered fo...
Article
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Inconsistences regarding flow measurements in real hydraulic circuits have been detected. Intensive studies stated that these errors are mostly associated to flowmeters, and the low accuracy is connected to the perturbations induced by the system layout. In order to verify the source of this problem, and assess the hypotheses drawn by operator expe...
Conference Paper
The estimation of unsteady parameters in two-phase condition is crucial for the safety and reliability of the hydraulic systems. There are plenty of one-dimensional (1D) simulation tools for unsteady flow estimation being some of them able to present good results in monophasic flows, while almost all of them are not suitable for two-phase flows. In...
Conference Paper
Filling and emptying operations should be planned by engineers in operational stages to prevent a system failure depending on reaching extreme low pressure values. In this sense, a compression of an air pocket produces pressure surges, while an expansion generates troughs of subatmospheric pressure. A sensitivity analysis of main hydraulic and ther...
Article
The prediction of the pressure inside the air pocket in water pipelines has been the topic for a lot of research works. Several aspects in this field have been discussed, such as the filling and the emptying procedures. The emptying process can affect the safety and the efficiency of water systems. Current research presents an analysis of the empty...
Article
Full-text available
REDAWN project will foster the adoption of hydropower energy recovery technology in built water networks in the Atlantic Area (AA). REDAWN will develop an adequate institutional, social and technological environment to foster greater resource efficiency in water networks. Pumps working as turbines (PAT) and other converters (wheels) became attracti...
Chapter
PATs are a viable and low-cost solution suitable for implementation in water networks. The basic economic parameters, the time value of money, methods of economic evaluation and the effects of the lifetime cycle are presented. The determination of analytical formulas to predict the PAT purchase price is shown. The installation of a PAT as a replace...
Chapter
Users, researchers and engineers require a fundamental knowledge of reverse pump theory. In this chapter first, a complete description of all PAT components is given. Then, the theory of small reverse pumps is described, based on the results of theoretical analyses, experiments and numerical simulations. PAT characteristic and efficiency curves are...
Chapter
The main rules for the selection of the regulation mode of a PAT based on the operating conditions are presented, as measured at the point of the network where the power plant will be located. The variability of operating conditions in water supply networks is discussed and the influence of the daily demand variation of the flow rate and available...
Chapter
A number of existing hydropower plants are described, which have a power generation capacity ranging between a few kW and a hundred kW, thus proving the extreme flexibility of PAT technology. Several different designs are shown, with the best solution depending on the power plant data and on the problem constraints. In addition, the layout of some...
Chapter
A PAT normally has a lower efficiency than a conventional turbine applied at the same site. In the long term, a higher efficiency is important for users in that more energy is produced. A pump’s geometry can be modified to improve its efficiency in turbine mode. Several methods of PAT geometry modification are presented for the improvement of PAT e...
Chapter
The importance of pressure control in water transmission systems with the identification of flow energy dissipation points is presented. The numerical methods used to analyze the behavior of the hydraulic system, the control valve maneuvers, and the over-speed effect associated with the dynamic behavior of the PAT are discussed. The dynamic control...
Chapter
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 ma...
Chapter
A simple methodology for PAT selection starting from the performance of the pump in direct mode is given, based on a number of studies on PAT behavior present in expert literature. The expected errors in terms of head and PAT efficiency between the results of this methodology and the experimental data are also discussed, and the possibility of intr...
Article
Full-text available
The EU funded Interreg project REDAWN is presented, setting a new operational framework for efficiently foster micro-hydropower in water distribution.
Article
The installation of hydropower plants equipped with pumps as turbines (PATs) in water supply systems has been demonstrated to be suitable and advantageous in order to both reduce pressure and recover energy. However, certain technical difficulties have delayed the widespread adoption of this innovative approach. The design of a hydropower plant wit...
Article
An air pocket’s behaviour inside of a pipeline during transient conditions is of great importance due to its effect on the safety of the hydraulic system and the complexity of modeling its behaviour. The emptying process from water pipelines needs more assessment because the generation of troughs of subatmospheric pressure may lead to serious damag...
Article
Full-text available
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...