1,721,344 research outputs found
Experimental and Numerical Investigation of Pumps As Turbines in Water Distribution Networks
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IL RECUPERO ENERGETICO NELLE RETI DI DISTRIBUZIONE IDRICA
No full textThe water resource represents the "blue gold" of the third millennium, not only in developing countries but also in urbanized areas. Indeed, the per-capita water availability is progressively decreasing - also due to ongoing climate changes - and the lack of resources is provoking, on one hand, the huge exploitation of water bodies and, on the other hand, the search of new supply source, resulting in significant contrast with the principles of environmental sustainability. In the next future the stresses deriving from the water resources exploitation (water stress level) will become increasingly intense in most countries in the world, mainly due to climate change, with a related increase in the intensity of extreme phenomena, with particular regard to drought. During the last decades, to assure a sustainable exploitation of water resources, the topics concerning the water savings and the energy consumption efficiency are more and more current.
Thus, as part of the Integrated Water Service (SII) management, a significant amount of energy is required for the supply, transport, use, treatment and release of waste water to the receiving water bodies. The amount of energy required to operate a water system certainly depends to a significant extent on the topographical characteristics of its networks, on the availability and quality of resources and on the type of treatments. On average, energy costs represent about 35% of the operating costs of the service. Today in Italy the total consumption of electricity in the SII is estimated to be around 7.5 billion kWh/year, corresponding to around 2.5% of national electricity consumption, a value in compliance with that of the other countries having infrastructure degree comparable to the Italian one. This rate will further increase over the next few years, as a consequence of the demand increase and the increasingly restrictive regulatory standards set for water treatment.
The reduction of energy consumption in the urban water cycle is therefore significantly pivotal. First of all, it is certainly related to a higher conscious exploitation of water resources, based on the consumption decrease and the reduction of water losses in water systems, namely in Water Distribution Networks (WDNs). Indeed, in Italy and, especially in the Southern Region, they represent a significant rate of the inflow resources, strongly higher than the typical physiological values. Water losses in Italian WDNs are on average of about 40%, corresponding to 3.45 million cubic meters in 2015. In greater detail, real water losses, caused by the decay or corrosion of pipes, cracks or flaw joints and inefficiencies are equal to 38.3% of the input volumes in the network, whereas the apparent water losses, related to unauthorized consumptions and measurement errors, are equal to 3.1%. The most affected Italian Regions concern some areas of the South, with percentages even reaching 60%.
In this field, the development of management practices aimed at the active control of the WDNs operations must be devoted to the reduction of excess pressures, in order to limit the excessive stresses of the components, capable of undermining their integrity, and to reduce water losses (due to the relationship between losses and pressures). The possibility of combining the pressure regulation (Pressure Management) with the small-scale hydropower generation in urban areas, therefore, represents a novel approach, achievable through the effective selection and management of devices for electrical generation in WDNs.
In this paper, an in-depth analysis on the criteria for carrying out energy recovery in WDNs is provided, with specific reference to the assessment of both the currently available devices and the issues deriving from their application in the network. Specific attention is paid to the use of pumps running in reverse operations (Pumps As Turbines, PATs), by both providing their main peculiarities and discussing the theoretical and applicative literature approaches for their application in WDNs
Indirect evaluation of erosion entity in drainage basins through geomorphic, climatic and hydrological parameters.
No full textThe regression equations connecting suspended sediment yield by streams with some parameters - expressing the main climatic, hydrologic and morphologic characters which control erosion intensity in drainage basins - were improved by extending the quantitative geomorphic studies already started by the authors on drainage networks. To have a sample which is representative of the different physiograpic conditions of Italy, twenty drainage basins were chosen. -from Author
A harmony-based calibration tool for urban drainage systems
No full textThe US Environmental Protection Agency’s storm water management model SWMM 5·1 is widely used to simulate
urban drainage processes both for qualitative and quantitative analysis. In the present work, SWMM 5·1 was applied
to the Fossolo urban sub-catchment in Bologna, Italy, and the geographic information system ArcGIS was adopted
to reproduce the spatial distribution of rainfall. An innovative and original optimisation procedure was developed,
coupling the jazz-music-based harmony search evolutionary algorithm with SWMM 5·1 for the estimation of runoff
parameters. Seven historical storm events were taken into account for model calibration and validation. A careful
sensitivity analysis highlighted the effectiveness of the calibrated parameters for simulations. The results obtained
showed the proposed approach to be a useful tool for the calibration of hydrological parameters in large urban
drainage systems, defining a satisfactory correlation between modelled and measured data
Variazioni della linea di riva lungo la maremma tosco-laziale, tra Ansedonia e Capo Linaro
No full textAn Application of the Harmony-Search Multi-Objective (HSMO) Optimization Algorithm for the Solution of Pump Scheduling Problem
No full textAbstractIn hydraulic systems, water is often pumped to reach higher elevations, so as to ensure the minimum required pressure and guarantee adequate service level. However, pumps cannot be instantly activated and people do not consume the resource in uniform mode throughout the day. To avoid direct pumping, water can be stored in tanks at a higher elevation, so that it can be supplied whenever there is a higher demand. Because of the significant costs required for pumping, energy-saving in water supply systems is one of the most challenging issues to ensure optimal management of water systems. Careful scheduling of pumping operations may lead not only to energy savings, but alsoto prevent damages, as consequence of reduction of operation times and switches. By means of computer simulation, an optimal schedule of pumps can be achieved using optimization algorithms. In this paper, a harmony-search multi-objective (HSMO) optimization approach is adapted to the pump scheduling problem. The model interfaces with the popular hydraulic solver, EPANET 2.0, to check the hydraulic constraints and to evaluate the performances of the selected schedules. Penalties are introduced in the objective function in case of violation of the hydraulic constraints. The model is applied to a case study, showing that the results are comparable with those of competitive meta-heuristic algorithms (e.g. Genetic Algorithms) and pointing out the suitability of the HSMO algorithm for pumping optimization
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