1,720,959 research outputs found
A new mixed integer non-linear programming model for optimal PAT and PRV location in water distributionnetworks
No full textWater distribution network are energy-demanding systems affected by low efficiency. In such systems, the pressure is generally kept under control by regulation valves to reduce the waste of water due to the leakages. The employment of energy production devices may be an efficient strategy to both reduce waste of water and produce energy, whose feasibility basically depends on the amount of recoverable energy, though. In this study, the optimal location of both pumps as turbines (PATs) and pressure-reducing valves (PRVs) within a literature water distribution network is investigated to maximize the production of energy and water savings. A new mixed integer non-linear model has been developed and a global optimization solver has been employed to perform the optimization. According to the results, the new optimization ensures good solutions, in term of water and energy savings, when compared with other procedures in literature
Energy transfer from the freshwater to the wastewater network using a PAT-equipped turbopump
Full text linkA new strategy to increase the energy efficiency in a water network exists using turbo pumps, which are systems consisting of a pump and a turbine directly coupled on a same shaft. In a turbo pump, the pump is fed by a turbine that exploits a surplus head in a freshwater network in order to produce energy for one system (wastewater) and reduce the excess pressure in another (drinking water). A pump as turbine (PAT) may be preferred over a classic turbine here due to its lower cost. The result of such a coupling is a PAT-pump turbocharger (P&P). In this research, the theoretical performance of a P&P plant is employed using data from a real water distribution network to exploit the excess pressure of a freshwater stream and to feed a pump conveying wastewater toward a treatment plant. Therefore, the P&P plant is a mixed PAT-pump turbocharger, operating with both fresh and wastewater. A new method to perform a preliminary geometric selection of the machines constituting the P&P plant has been developed. Furthermore, the plant operation has been described by means of a new mathematical model under different boundary conditions. Moreover, the economic viability of the plant has been assessed by comparison with a conventional wastewater pumping system working in ON/OFF mode. Therefore, the net present value (NPV) of the investment has been evaluated in both situations for different time periods. According to the economical comparison, the PAT-pump turbocharger represents the most economically advantageous configuration, at least until the useful life of the plant. Such convenience amounts to 175% up to a time period equal to 20 years
Potential Energy, Economic, and Environmental Impacts of Hydro Power Pressure Reduction on the Water-Energy-Food Nexus
No full textThe installation of hydropower pressure reduction (HPPR) technology in water supply networks (WSN) has recently been encouraged to limit water losses through leakage. Traditionally, pressure reducing valves (PRVs) were positioned at strategic nodes in a water network and were operated continuously to dissipate excess energy and minimize pipe failure. The alternative adoption of low-cost and highly reliable HPPR technology - Pump As Turbine (PAT) - can recover energy to improve the sustainable management of water networks and increase the energy, economic, and environmental benefits derived from the provision of water resources. To encourage the exploitation of HPPR, indicators and metrics were developed and applied for a case study (olive crop production with an irrigation network in Andalusia, Spain). The case study incorporated (1) a number of WSN scenarios based on water supply conditions, location of the HPPR within the network, and pipe age; (2) the expected performance of the PAT in the market; and (3) the expected optimal performance of an HPPR design based on a variable operation strategy (VOS). Independent life cycle indicators and nexus metrics were created to enhance the evaluation of the performance of HPPR technology as part of the water-energy-food nexus. In this case study, the new metrics expressed the impact of HPPR technology on the water-energy food nexus in terms of climate change and in the context of olive production in an irrigation network. The methodology for assessing combined energy, economic, and environmental metrics (3EM) can be used to account for the value of HPPR deployment in any WSN. These metrics can inform local decision makers and national policy makers, by providing relative and/or absolute evidence on the environmental impacts of HPPR technology in the water sector
A New Low-Cost Technology Based on Pump as Turbines for Energy Recovery in Peripheral Water Networks Branches
Full text linkThe 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 rate and head drop within
water distribution networks, the operation of PATs could be performed by a series-parallel regulation
system based on an electronic or a hydraulic principle. Despite the low cost of the PATs and of
regulation and control systems, a great barrier to the diffusion of a small hydro power plant in water
distribution is represented by the necessity of additional civil works to host the whole plant. Based
on laboratory and numerical experiments, the present paper proposes a new low-cost technology,
overcoming most of the limitations of the present technologies when low energy is available and
high discharge variation occurs. The operating conditions of the plant are properly optimized with
reference to the working conditions of a case study. Despite the laboratory prototype having exhibited
a significantly low efficiency (i.e., 16%), due to the use of small centrifugal pumps suitable for the
analyzed case study, in larger power plants relying on more efficient semi-axial submersed pumps,
the energy conversion ratio can increase up to 40%. The results of this research could be useful for
network managers and technicians interested in increasing the energy efficiency of the network and
in recovering energy in the peripheral branches of the network were a large variability of small flow
rates are present
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
New Challenges towards Smart Systems’ Efficiency by Digital Twin in Water Distribution Networks
Full text linkNowadays, 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 energy losses. In particular, Digital Twins (DT) represents a very innovative technology, which relies on the integration of virtual network models, optimization algorithms, real time data collection, and smart actuators information with Geographic Information System (GIS) data. This research defines a new methodology for an efficient application of DT expertise within water distribution networks. Assuming a DMA of a real water distribution network as a case study, it was demonstrated that a fast detection of leakage along with an optimal setting of pressure control valves by means of DT together with an optimization procedure can ensure up to 28% of water savings, contributing to significantly increase the efficiency of the whole system
Pressure Drop and Energy Recovery with a New Centrifugal Micro-Turbine: Fundamentals and Application in a Real WDN
No full textWater 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 is performed with the aim of investigating the optimal location of both the designed new centrifugal micro-turbines (CMT) and pressure reducing valves (PRV) in order to control the excess of pressure and produce energy at the same time
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