Search Results (18)

Since their development, as a result of an improvement of labyrinth weirs, Piano Key Weirs (PKWs) have been implemented as (a) a flood safety structure for gravity dams, allowing to also increase their storage volume, and (b) in river systems to increase the water level for hydropower or navigation purposes. The rectangular folded crest, consistent with apexes inclined by turns in the upstream and in the downstream direction, turns the PKW a device with a high discharge capacity, especially useful during wet extreme events. Nevertheless, several modifications have been implemented in the PKW geometry, capable to improve and, in some cases, worsen their efficiency. Herein, an experimental and numerical assessment, using the ANSYS Fluent Computational Fluid Dynamics (CFD) software, of the discharge coefficient is presented for two PKW configurations, evaluating the specific discharge over the upstream, downstream, and lateral crests, the velocity in the inlet and outlet keys, and the water surface profile, as well. The investigated configurations are a symmetric type A, designed following the recommended optimal values, and a type B model, with the same geometric features as type A. Results showed that for the specific geometries, the type B is more efficient for lower head; however, once the filling of the outlet key occurs, the type B efficiency is reduced, leading to type A becoming more efficient. Full article

Optimizing pump operation in water networks can effectively reduce the cost of energy. To this end, the literature provides many methodologies, generally based on an optimization problem, that provide the optimal operation of the pumps. However, a persistent shortcoming in the literature is the lack of further analysis to assess if the obtained solutions are feasible from the technical point of view. This paper first showed that some of these available methodologies identify solutions that are technically unfeasible because they induce tank overflow or continuous pump switching, and consequently, proposed a novel approach to avoiding such unfeasible solutions. This consisted in comparing the number of time-steps performed by the hydraulic simulator with the predicted value, calculated as the ratio between the simulation duration and the hydraulic time-step. Finally, we developed a new model which couples Epanet 2.0 with Pikaia Genetic Algorithm using the energy cost as an objective function. The proposed method, being easily exportable into existing methodologies to overcome the limitations thereof, thus represents a substantial contribution to the field of pump scheduling for optimal operation of water distribution networks. The new method, tested on two case studies in the literature, proved its reliability in both cases, returning technically feasible solutions. Full article

The present work describes the design process of a 3D-printed prototype of a three-blade horizontal-axis hydrokinetic water turbine (HAHWT). The employed blade profile is an EPPLER818, which was previously studied through the Q-Blade software according to the velocity range presumed (v < 1 m/s) in the experiments. The prototype performance was studied in a recirculating water channel at the Polytechnic Engineering School of Mieres (Oviedo University), with a gate of variable height at the channel end, which allows for performing different hydrodynamic scenarios upon varying the considered flow rate. The results show that the extracted power increases due to the equally increased blockage ratio, which represents the ratio between the turbine area and the channel area. However, an excessive increase in the blockage ratio corresponds to a power reduction effect due to the reduction in the effective area and the generation of a two-phase air-water condition. Full article

According to the Sustainable Development Goals included in the 2030 Agenda signed by 193 UN member countries, one of the expected targets is the improvement of Water Management through sustainable and efficient practices. Italy holds the record among the European Union countries for the highest withdrawal of water for drinking use per capita: in 2020, 9 billion cubic meters of water were supplied to users, corresponding to 152.4 m³ per inhabitant per year, with a progressive worsening in the efficiency of the distribution systems. The modernization of poor infrastructure is, therefore, the main driver for reversing this negative trend in the Integrated Water Service. In the case of water, “Smart” consists of making water supply and distribution intelligent with Internet of Things (IoT) technologies so as to allow reciprocal connection and communication with other parts of the plant and city. Smart water systems use sensors activated by the IoT to collect data in real time and generate the so-called “Digital twin”, which is the digital twin of the physical infrastructures present in the area and allows a modern and optimized management. This allows optimization of water structures by detecting leaks in the network and by the users, flow rates, pressures or control of the distribution of water on the network and allows operators to make more informed decisions regarding the management of water resources, also with regard to qualitative parameters. The processes currently underway at many water managers of districting and modeling of water networks cannot ignore ever greater sensorization of the assets and ever more refined processing of the data generated by them. These structures, connected and integrated by means of native IoT communication networks, public and standard, will allow significant water savings, reducing losses due to malfunctions and breakdowns. Furthermore, they will allow savings on the bill for the private citizen and a reduction in waste, an absolutely fundamental issue in a world that is becoming more and more populated and which, up to now, has treated natural resources as if they were infinite and guaranteed. Full article

The United Nations defines Water Security as “the capacity of a population to safeguard sustainable access to adequate quantities of acceptable quality water for sustaining livelihoods, human well-being, and socio-economic development, for ensuring protection against water-borne pollution and water-related disasters, and for preserving ecosystems in a climate of peace and political stability” [...] Full article

Water demand scenarios are defined assuming that the samples are complete. On the other hand, consumption measurements are often affected by a considerable number of missing data. This paper explores the problem of missing data and proposes an example of a data pre-processing technique. Afterwards, a deconstruction of the time series, without being influenced by the presence of gaps, is presented. For this purpose, the fast Fourier transform for nonuniform sampling is developed. This analysis allows us to generate ergodic and stationary samples, useful for pursuing the generation of water demand scenarios. An application is provided on a water consumption time series recorded in a suburban area of Naples, Italy. Full article

The current significant increase in energy consumption has resulted in the need to develop and implement effective approaches for defining alternative and sustainable solutions to couple primary resources with supporting methods of energy generation. In the field of effective water distribution network (WDN) management, the suitability of combining pressure regulation with small-scale hydropower generation is attracting even more interest, given that it can possibly reduce water leakages, as well as produce attractive rates of renewable energy. Specifically, pumps as turbines (PATs) are widely considered a viable solution because they combine hydraulic benefits with affordable investment and management costs. Nevertheless, despite several approaches available in the literature for the optimal selection and management of PATs, choosing the most suitable device to be installed in the network is still a challenge, especially when electrical regulation is arranged to modulate the PAT rotational speed and optimize the produced energy. Several approaches in the literature provide interesting solutions for assessing the effectiveness of electrical regulation when a PAT is installed within a water network. However, most of them require specific knowledge of the PAT mechanical features or huge computational efforts and do not support swift PAT selection. To overcome this lack of tools, in this work, an operative framework for the preliminary assessment of the main features (the head drop and the produced power at the best efficiency point (BEP), the impeller diameter and the rotational speed) of a PAT is proposed, aimed at both maximizing the daily produced energy and performing challenging economic selection. Then, it is assessed by estimations of the corresponding payback period (PP) and the net present value (NPV). Full article

In mountain areas, natural hazards, e.g., flooding, snow avalanches, droughts, and landslides are triggered by climate change, anthropization, and economic development. Nature-Based Solutions (NBSs) are attracting increasing interest as they are able to couple technical solutions against natural hazards with ecological and socio-economic resilience. On this matter, the four-year H2020 Innovation Action “PHUSICOS—According to Nature” (Grant Agreement nr. 776681) project aims to assess the effectiveness of NBSs and hybrid solutions to hinder hydro-meteorological events in rural and mountainous areas in Europe. Among the ongoing activities within the project, a multi-criteria tool was implemented to assess the effectiveness of NBSs measures from the technical, environmental, and socio-economic perspectives. In this work, the preliminary application of the assessment tool to the Isar River (DE) PHUSICOS concept case is discussed, with reference to an ex-post analysis of the flood risk management plan, comparing the performances of the implemented NBS project scenario against a potential grey solution. Full article

This paper presents a comparison between two procedures for the generation of water demand time series at both single user and nodal scales, a top-down and a bottom-up procedure respectively. Both procedures are made up of two phases. The top-down procedure adopted includes a non-parametric disaggregation based on the K-nearest neighbours approach. Therefore, once the temporal aggregated water demand patterns have been defined (first phase), the disaggregation is used to generate water demand time series at lower levels of spatial aggregation (second phase). In the bottom-up procedure adopted, demand time series for each user and for each time step are generated applying a beta probability distribution with tunable bounds or a gamma distribution with shift parameter (first phase). Then, a Copula based re-sort is applied to the demand time series generated to impose existing rank cross-correlations between users and at all temporal lags (second phase). For the sake of comparison, two case studies were considered, both of which are related to a smart water network in Naples (Italy). The results obtained show that the bottom-up procedure performs significantly better than the top-down procedure in terms of rank-cross correlations at fine scale. However, the top-down procedure showed a better performance in terms of skewness and rank cross-correlation when the aggregated demands were considered. Finally, the level of aggregation in nodes was found to affect the performance of both the procedures considered. Full article

In this work, a procedure for the optimal design of Pumps As Turbines in Water Distribution Networks was applied, aimed at both maximizing the hydropower generation and exploiting the excess pressure. The design of the main characteristic PAT parameters, namely the flow rate and the head drop at Best Efficiency Point, the rotational speed and the impeller’s diameter was assessed, under the hypothesis of applying the Electrical Regulation. The procedure allowed to estimate both the produced power and the exploited head at any simulated time-step, as well as the overall daily energy, in compliance with the hydraulic and technical constraints of the system. The model was tested on a simplified Water Distribution Network and a preliminary Cost-Benefit analysis was performed, showing interesting reliefs against short Payback Period. Full article

In the present paper, different clustering techniques were applied to detect significant patterns describing single-household water consumption in a residential neighborhood of the City of Naples, basing on hourly time series aggregated at the monthly scale. Comparisons among results were performed by means of a selection of Clustering Validity Indices, that were adjusted to overcome a bias caused by sparsely populated clusters. The most performant cluster solution proved to be the one resulting from the application of a mixed strategy, namely a Self-Organized Map followed by K-means performed on first level cluster centroids. Full article

In this paper preliminary results of the numerical assessment of PAT erosion, caused by the impingement of solid particles in the water flow, are provided and discussed. A CFD model was developed by the Università degli Studi di Napoli Federico II to investigate the fluid dynamics of a PAT and coupled with the in-house E-CODE developed by the Politecnico di Milano for wear estimation. The erosion simulations were performed to assess the wear of PAT components, namely inlet, impeller, volute and outlet pipe, for abrasive particles with different size, aiming at estimating the relation between the fluid dynamics of the slurry flow and the development of the erosion process. Full article

Pumps As Turbines (PATs) can be installed in Water Distribution Networks (WDNs) to couple pressure regulation and small-scale hydropower generation. The selection of PATs in WDNs needs proper knowledge about both the performances of machines available in the market and the operating conditions of the network. In this paper, a procedure for the preliminary selection of a PAT is proposed, based on the design of the main parameters (the head drop and the produced power at the Best Efficiency Point, the impeller diameter and the rotational speed) to both maximize the producible power and regulate the exceeding pressure. Full article