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Pressurised pipe systems transport fluids daily over long distances and sediment deposits are responsible for narrowing the cross-sectional area of the pipe. This reduces the carrying capacity in gravity pipes and increases the energy consumption in rising mains. As partial blockages do not give rise to any external evidence, they are considered the most insidious fault occurring in pipe systems. Thus, the refinement of reliable techniques for detecting partial blockages at an early stage is of great interest to water utilities. This paper presents a computational fluid dynamics (CFD)-based analysis of the steady-state flow through a sharp-edged orifice which corresponds to the most straightforward partial blockage feature in a pipe. The main motivation is the fact that the interaction between pressure waves and a partial blockage – on which Transient Test-Based Techniques for fault detection are based – is strongly influenced by the pre-transient conditions at the partial blockage. The refined CFD model has been validated by considering experimental data selected from the literature. The comparison of obtained results demonstrates good performance of the numerical model. This authorised exploring in detail the features of the flow through the orifice as a necessary premise to its use within the successive transient analysis. HIGHLIGHTS A comprehensive analysis of the low-Reynolds number flow through a sharp-edged orifice (partial blockage) is provided by computational fluid dynamics (CFD).; The successful comparison of CFD with reference papers demonstrates that the model accurately describes the laminar flow through an orifice in steady-state conditions.; The obtained results can be further used for the transient analysis of the interaction between a pressure wave and the obstacle.

Through always more innovative IT applications, the construction industry is moving towards the digitalization of the building process, from digital design to automated manufacturing and smart buildings. Big data are now able to take us into an augmented reality—the virtual sibling of the real one—where buildings become cognitive and predictive, capable to actively interact with people. Towards this direction, the capability to store and organize building information at any level of its lifecycle is essential, especially when the multi-criteria evaluation of buildings’ behavior is required. Within this framework, the chapter introduces the review of the standards and best practices, mainly focusing on BIM as the driven method for the management of the entire building process. Hence, the methodology to develop a new assessment tool is presented, according to the investigation of the current platforms for the evaluation of buildings’ performances, and the pursued methods to define new additional shared parameters, specifically customized for the application to retrofit design solutions with timber-based construction systems.

A pressure reducing valve (PRV) regulates the outlet pressure regardless of the fluctuating flow and varying inlet pressure, thereby reducing leakage and mitigating the stress on the downstream water distribution network (WDN). Notwithstanding the crucial importance of PRVs, few experimental data are available in the literature. The aim of this paper is to overcome this gap by means of the results of a large number of tests carried out at the Water Engineering Laboratory of the University of Perugia, Italy. These tests have been executed on a standard type of PRV in steady-state conditions, to characterize it, and in unsteady-state conditions, to check its transient response. A broad range of laboratory conditions simulating possible events in WDNs has been examined and both short and long duration monitoring have been carried out. The analysis of the tests demonstrates the versatility of PRVs as a powerful tool for pressure management, and also when the flow condition changes according to the users' demand pattern. In fact, their transient response is appropriate with small pressure oscillations generated by the PRV self-adjustment. Moreover, proper PRV modelling has to include both its mechanical behaviour and the characteristics of the pressure pipe system in which it is installed.

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 T&eacute, cnico based on a transient-flow induced compressed air energy storage (TI-CAES) system, which takes advantage of a compressed air vessel (CAV). The CAV can produce extra required pressure head, by compressing air, to be used for either hydropower generation using a water turbine in a gravity system or to be exploited in a pumping system. The results show a controlled behaviour of the system in storing the pressure surge as compressed air inside a vessel. Considerable power values are achieved as well, while the input work is practically neglected. Higher power values are attained for bigger air volumes. The TI-CAES offers an efficient and flexible solution that can be exploited in exiting water systems without putting the system at risk. The induced transients in the compressed air allow a constant outflow discharge characteristic, making the energy storage available in the CAV to be used as a pump storage hydropower solution.

Digital design is increasingly sinking the construction sector, shaping and validating architecture according to various criteria and introducing the wood industry to the 4.0 approach. Within the study entitled “Architecture at Arte Sella”, parametric design, structural validations and CNC procedures are exploited to help define, control and assess several architectural woodworks, created with famous designers. This contribution describes the design and construction experiences of Atsushi Kitagawara (2017) and Kengo Kuma (2018–2019), the two masterpieces installed in the land art park of Arte Sella (Trento, Italy) and developed, thanks to the Politecnico di Milano team, from design to mock-ups, testing and construction.

In this paper the possibility of using transient tests, generated by the Portable Pressure Wave Maker (PPWM) device, as a powerful tool for singularity detection, is checked in a real transmission main. During tests, small pressure waves – with an entity smaller than 1 m of water column – are injected by means of the PPWM, just upstream of the end reservoir. The results of the field test are discussed in terms of the time needed to prepare the experiments, their repeatability, and effectiveness of the injected pressure waves.

Plastic/viscoelastic pipes, such as polyvinyl chloride (PVC), polyethylene (PE) and high-density polyethylene (HDPE), have been increasingly used in water piping systems, which has stimulated the study of viscoelastic hydrodynamics in these pipe systems. An in-depth understanding of the pipe-wall viscoelasticity features is beneficial and necessary to the effective application and management of plastic pipes such as leak detection in urban water supply systems. This paper presents a frequency response function (FRF)-based transient wave analysis method (TWAM) for the identification of viscoelastic pipe properties as well as the detection of leaks in water filled plastic pipes. To this end, an analytical FRF expression is firstly derived for the interaction of transients with pipe-wall elasticity and leaks in plastic pipes, which is thereafter used for the identification of viscoelastic parameters and potential leaks in plastic pipes. Laboratory experiments are performed to validate the proposed FRF-based TWAM and thereby examining the effective range of injected wave bandwidth for accurate leak detection with existence of pipe-wall viscoelasticity. The validated method is further analyzed through extensive numerical applications to systematically examine the influences of different system and flow conditions. Application results confirm the feasibility and accuracy of the developed FRF-based TWAM method for the identification of viscoelastic parameters as well as the detection of plastic pipe leaks. The results also indicate that the proposed method in this study is more accurate to locate leaks than to size leaks in plastic pipes, which requires more attention to the future applications.

Several shelters have been recently developed by Politecnico di Milano for different purposes but with a common character: smallness. Small is More shows how workshops with students can be extremely efficient and productive on real targets and how materiality is important to learn and step over any parametric approach. Of course, parametric tools can be very useful to manage the design phase and optioneering strategies but, in the end, only real built structure unveils the power of architecture. The paper will show some of this examples where Smallness can be of great effect: Akragashelter in Agrigento—Valle dei Templi (UNESCO Workshop), with a structure in gabion-wall, the roof in fir wood, and parametric design; C-ASA, Active House Shelter in Lecco (Politecnico di Milano ASA Workshop), with CLT structure, aerospace thermo-reflective insulations, and zinc-titanium outer skin; Equilatera, the social Shelter in Favara (FARM Cultural Park), digitally designed, with recycled CLT wasted studs for the structure; Teagloo, in Tokyo with Kengo Kuma Lab (The University of Tokyo), digital designed structure in sushi bamboo baskets, with FRP reinforcements; Veneer House, in VIS (Croatia) with Prof. Hiroto Kobayashi and KOBAYASHI MAKI DESIGN WORKSHOP (Keio University, Tokyo). The learning process has been thought with real targets for social purpose and students have participated in designing real case studies, which are now still in full function.

KODAMA is the new “sculpture” conceived by Kengo Kuma for Arte Sella—The Contemporary Mountain. The process shows the concept, the development, and the construction of a complex structure in massive wood (Italian larch), a new sculpture in this famous Land art park. After the first options, which have been discussed between the Japanese and the Italian teams, a solution with lattice blades has been chosen. The first phase was to produce different scale mockups, both analogic and digital in order to find proportion and dimensions. All the structure which creates a kind of “porous sphere” (a polyhedron) is made only by one wood section, connected without nails or screws. Old toys, Chidori-like, are the reference and several scaled mockups have been produced with different woods: cedar, larch, fir, and oak. Once assessed the architectural/spatial shape the model has been studied for its structural behavior thanks to complex software analysis, which have been studied using the parametric model (Rhino-Grasshopper). Models have been used for testing the structure after assessing the real loads (mainly snow and wind). Full scale 1:1 mockup have been realized both analogic and with CNC machines by master carpenters. The final shape is an ideal “Teahouse” space in the middle of the forest, close to Villa Strobele, which will be the new core of Arte Sella, dedicated to famous architects and their ways to conceive art and nature using wood as a creative material.

International standards and constantly smarter practices are everyday more addressing the issue of a sustainable development. However, this virtuous approach has to involve the final users, in a newer and wider perspective: People First. This is the aim of the Active House Alliance, proposing a new vision for the future of the construction sector. Indoor comfort and occupants’ wellbeing, energy efficiency and renewable sources exploitation, eco-friendly approaches are integrated into new guidelines and technical prescriptions, to help designers in developing the active buildings of the future.

According to the European Directive, the Nearly Zero Energy Building standard (NZEB) represents a backbone to achieve the European CO2 emission reduction target considering both, new and under renovation buildings. In this chapter, the Maison Verte, a low energy residential building, located in northern Italy has been presented showing the sustainable design approach, the technological design and his energy and comfort rating. The building represents a high energy efficient case study building, in which, the principles of comfort (visual and thermal), energy and environment are perfectly balanced according to the voluntary Active House certification scheme. During the design phase, the overall building performances has been deeply analyzed applying a multi-disciplinary design optimization process tools where parametric design, financial models and energy simulation tools are combined to accelerate the design phase and explore design options faster and more effectively than current conventional design process.

Active House principles represents an affordable element that could drive the design process in different stages. At Politecnico di Milano, several experimental activities have been conducted on its prototypes buildings, in order to mind the gap between the predicted, simulated, observed, and recorded building behavior. Therefore, the AH vision—with its Specifications and Guidelines—has been applied to the validation of these two innovative small buildings: VELUXlab and C-ASA. The final aim is multiple: at first, the analysis of the building features in relation to a specific climate context (the Mediterranean area); then, the information of the users, in order to educate them to the correct use of this smart objects.

Pressure control strategy through Pressure Reducing Valves (PRV) has been deeply investigated as management strategy, aimed at water leakages reduction avoiding very expensive pipe replacement programs. On the contrary, few experimental data are available in literature, with regard to PRV transient behavior in terms of its response to incoming pressure waves, as well as the time required for achieving the pressure set point. In this paper, the results of some experimental tests are presented. The PRV is installed in a single high density polyethylene pipe and transients are generated by operating the downstream end valve. Two types of tests are considered: a partial valve closure and opening simulating a water demand decrease and increase, respectively. The analysis of the experimental pressure traces points out the valuable effects of the PRV on transient characteristics with respect to the case of a partially closed in-line valve with a constant opening degree.

Eigenfrequency shift in a pipe with a blockage is investigated experimentally. The experimental test rig consists of a reservoir-pipe-valve (RPV) system that contains a single partial block...

We have monitored the presence of bacteria belonging to the genus Legionella in the plumbing of buildings at the University of Perugia (Italy). More than 300 water samples were collected from 156 control-point taps in 41 buildings comprised in the eight campuses of the University. Legionella was absent in most samples, while it was found in only 12 buildings (29% of the total). Molecular analysis indicated the presence of L. pneumophila (serogroups 1, 8 and 6–10), L. taurinensis and L. anisa. In only three cases contamination levels were above the limit at which remedial actions are required, according to international guidelines. In two buildings, where the water temperature could be raised and maintained above 60 °C, thermal disinfection was effective in eradicating Legionella. Conversely, in buildings where contaminations were caused by heat exchangers that produced hot water at a maximum temperature of 50 °C, a chemical disinfection with silver hydrogen peroxide was carried out but was effective only in the short term. In this case study, Legionella contaminations and remediation effectiveness strongly depended on the network and heating-system characteristics, indicating how a multidisciplinary approach that integrates microbiological analysis with hydraulic surveys is necessary for an effective definition of Legionella prevention and control strategies.

In this paper, the reliability of transients due to pump trip as a powerful tool for the pre-localization of anomalies in real pipe systems is tested. The examined pipe system is part of the one supplying the city of Milan, Italy and is managed by Metropolitana Milanese SpA (MM). The characteristics of such a system can be considered as intermediate between those of classical transmission mains and distribution systems because of its several branches. A Lagrangian model simulating pressure wave propagation is used to evaluate the pipe pressure wave speed – associated with a genetic algorithm – and to locate possible anomalies – associated with wavelet analysis. The results of the diagnosis of the pipe system are corroborated by repairs executed by MM in the area where possible anomalies have been pre-localized.

The relationships between leak geometry and detectability are explored with a distinction between steady- and unsteady-state based techniques. Various criteria to evaluate the size and detectability of a leak are first discussed. These criteria can be useful for the benchmarking and the comparison of different techniques. Since the test conditions play a crucial rule in leak detectability, the proposed criteria take this effect into account. Further- more, they show that while in steady-state conditions increases in system pressure enhance leak detectability, in transient state, by contrast, higher pressures tend to decrease detec- tability. This effect is also confirmed by experimental tests carried out at the Water Engineering Laboratory of the University of Perugia.

The relationship between the functioning conditions of pipe systems and the leakage, or leak law, can be used at two different scales. At a local scale, i.e. for a single leak, it is derived from the classical orifice equation and, basing on experimental data, is modified to take into account all the relevant parameters it depends on (e.g., leak shape, pipe material and thickness, …). At a global scale, for a whole district or a part of a pressurized pipe system with several leaks, the same relationship is often used, basing on the assumption that the combination of local leak laws produces a similar global leak law. In this paper the effects of the spatial variation of the leak law parameters at the local scale on the leak law at a global scale are analyzed. Two leak laws derived from the orifice equation, the power law and the linear law, are considered. Results suggest that the global leak law exponent is larger than the corresponding mean local leak law exponent since it takes into account the spatial variability of the quantities affecting leakage.

In this paper, the reliability of transients as a powerful tool in the management of real water distribution system (WDS) is tested. The examined steel pipe system is the Novara WDS in the Northwest part of Milan, Italy and is managed by Metropolitana Mi- lanese S.p.A. The pressure signal acquired during the first phase of a test has been analyzed on the basis of the extensive research activity performed in the previous years in the field of transient test-based techniques for the diagnosis of pipe systems. The wavelet transform (WT), which allows the automatic detection of singularities in noisy pressure signals, and a Lagrangian model (LM), which evaluates the causes of discontinuities, are coupled for analyzing the pressure signal acquired in Novara WDS. The results of such an analysis are shown and the limitation of this methodology is checked; a more reliable test procedure is assessed.

The effect of demand uncertainty in water distribution systems (WDS) is a key problem, especially for water company assets. The presence or absence of demands, their number, size, and locations significantly affect the functioning of a pipe system and its response to a transient. The validity and the effectiveness of the Lagrangian model is firstly investigated by means of a comparison with a Method of Characteristics model in frictionless systems. Demands locations are stochastically varied to assess the impact of the uncertainty of the geometry of the network on transient propagation. A normal distribution has been used to model the uncertainty of demand location.

The Battle of Background Leakage Assessment for Water Networks (BBLAWN) is the fifth in a series of “Battle Competitions” dating back to the Battle of the Water Networks (BWN) in 1985 and, more recently, the Battle of the Water Sensor Networks (BWSN) in 2006; the Battle of the Water Calibration Networks (BWCN) in 2010 and the Battle of the Water Networks Design (BWN-II) in 2012. The BBLAWN asks for a design methodology for reducing water losses due to background leakages in a real water distribution system. The results have been presented at a special session of the 16th Water Distribution Systems Analysis Conference, held in Bari, Italy in July 2014, where 14 teams from academia, research centers and companies presented their solutions to the problem in hand.

In this study, an algorithm is presented for pipe system diagnosis. The algorithm is the Successive Linear Estimator (SLE) previously used in groundwater hydrology to estimate the hydraulic proprieties of soils. The SLE is an iterative cokriging-like technique which provides statistically the best unbiased estimates and quantifies the associated uncertainty. In this paper the algorithm has been extended to the pipe system diagnosis to infer leak areas, status of valves and partial blockage location and extent. We first present the theoretical formulation of the algorithm and then test it by a numerical case study.

Hydraulic transients (water hammer waves) can be used to excite a pressurized pipeline, yielding the frequency response diagram (FRD) of the system. The FRD of a pipeline system is useful for condition assessment and fault detection, because it is closely related to the physical properties of the pipeline. Most previous FRD-based leak detection techniques use the sinusoidal leak-induced pattern recorded on the FRD, either shown on the resonant responses or the antiresonant responses. In contrast, the technique reported in the current paper only uses the responses at the first three resonant frequencies to determine the location and size of a leak. The bandwidth of the excitation only needs to be five times that of the fundamental frequency of the tested pipeline, which is much less than the requirement in conventional FRD-based techniques. Sensitivity analysis and numerical simulations are performed to assess the robustness and applicable range of the proposed leak location technique. The proposed leak location technique is verified by both numerical simulations and by using an experimental FRD obtained from a laboratory pipeline.

Effective water system management depends upon knowledge of the current state of a water pipeline system network. For example, in many cases, partial blockages in a water pipeline system are a source of inefficiencies, and result in an increase of pumping costs. These anomalies must be detected and corrected as early as possible. In this study, an algorithm is developed for detecting blockages by means of pressure transient measurements and estimating the diameter distribution resulting from their formation. The algorithm is a stochastic successive linear estimator that provides statistically the best unbiased estimate of diameter distribution due to partial blockages and quantifies the uncertainty associated with these estimates. We first present the theoretical formulation of the algorithm and then test it with a numerical case study.

This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010), a pipe with a partially closed in-line valve (Meniconi et al., 2012a), and a pipe with cross-section changes in series (Meniconi et al., 2012b). Tests are based on laboratory experiments carried out at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy, and the use of different numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the examined transients.

Climate change influences hydrological cycle with a direct effect on groundwater resources, one of the most important supply sources for human consumption and irrigation. In a scenario where General Circulation Models do not represent yet a usual tool for water industry managers, potentially the use of global atmospheric datasets is of great interest for evaluating groundwater resources. In this paper data from the European Centre for Medium-Range Weather Forecasts (ECMWF) are compared to local water table measurements. With particular regard to unconfined aquifers, the good correlation between the trend of soil moisture and local water table data is pointed out. Such a promising result authorizes further insights in order to refine reliable tools for evaluating available groundwater resources in a climate change scenario.

The Aqualibrium competition [1] is a fun way to learn about water supply and distribution. A pipe network has to be built with the aim of equally distributing a given volume of water between three reservoirs. The rules of such a competition prescribe that a looped network has to be built and this makes the problem quite complex because of the well-known non-linearity of the governing equations. EPAnet is a powerful tool to improve and fasten the solution of the problem. At the Water Engineering Laboratory (WEL) of the University of Perugia an Aqualibrium equipment is used within the Civil Engineering courses. EPAnet was used to simulate the behaviour of the Aqualibrium network, but the results showed some discrepancies between laboratory tests and numerical simulations under some flow conditions. These discrepancies, as well as the critical role played by energy dissipation mechanism, are discussed in this paper.

The aim of this paper is to investigate the complex nature of the transient energy dissipation by using a computational fluid dynamics (CFD) model with a high spatial and temporal resolutio...

In this paper, the reliability of transient test-based techniques for detecting pipe system anomalies is shown by means of numerical and experimental tests – both in laboratory and real pipe systems – with particular regard to the case of a partially closed in-line valve. With regard to the analysis of pressure signals, attention is focused on the time domain approach. Moreover, the optimal modality of transient test execution is discussed. References concerning the diagnosis of other anomalies (e.g., leaks, partial blockages, and illegal connections) by means of transient tests are also included for the interested reader.

This paper presents the results of the calibration by means of a microgenetic algorithm, using Kelvin-Voigt viscoelastic parameters, to reproduce experimental unsteady flow tests in a polymeric pipe. During the tests, different pipe lengths—which give rise to different periods of the pressure oscillations—and initial discharges have been considered. The mechanical parameters of the viscoelastic models are estimated using both one-dimensional (1D) and quasi two-dimensional (2D) models. The calibration of Kelvin-Voigt models with 2, 3, 5, and 7 parameters, respectively, proves the substantial independence of the elastic modulus and the dependence of the retardation time on the pipe period (i.e., the pipe length). Moreover, in most cases, the increase in the number of mechanical parameters allows a better simulation of a single transient. However, the larger the number of parameters, the greater the risk of overfitting, and the more difficult the search for general laws of dependence of the parameter...

This paper analyses the mechanism of interaction between an incident pressure wave and blockages of different geometrical characteristics (i.e., a butterfly and a ball valves, two short stretches of pipe with a reduced diameter, and a device simulating a longitudinal body blockage) by means of laboratory and numerical tests. Experiments have shown that the mechanism of interaction with pressure waves is influenced by their path through the device: sinuous because of the device body for partially closed in-line valves (type I mechanism), and straight for the small bore pipe devices (type II mechanism). Type I mechanism is characterized by a rise followed by an almost constant value whereas in type II one a drop occurs after the rise. To complete the investigation the effect of the pre-transient condition is discussed.

Pressure control strategy through Pressure Reducing Valves (PRVs) has been deeply investigated as management strategy, aimed at water leakage reduction avoiding very expensive pipe replacement programmes. On the contrary, few experimental data are available in literature, particularly in unsteady-state conditions. In this paper, the results of some tests carried out at the Water Engineering Laboratory of the University of Perugia (I) in order to characterize a PRV with two set points for high and low pressures are presented. The PRV is installed in a single high-density polyethylene (HDPE) pipe supplied by a tank in which the pressure is assured by pumps of different characteristics. Two types of tests are considered: steady-state tests, to characterize the PRV, and extended period tests, to check its dynamic behaviour.

Wind power generation is growing rapidly in many locations around the world. Power systems are able to absorb large amounts of wind capacity, but operational problems arise when the wind power penetration becomes high. Such factors as voltage dips, frequency variations, low power system stability, low reactive power and power flow imbalances reduce the economic value and represent a barrier to the unlimited development of wind energy. Hydrogen production from wind power that is not matched with hourly electricity demand appears to be an attractive storage option capable of providing a balancing service to the electricity generators and suppliers for mitigation of the negative impacts due to the random nature of wind. Because of its multi-functionality, hydrogen can be used directly as a fuel, mixed with methane, or transmitted through pipelines to the users. The aim of this paper is to produce useful suggestions for the planning, development and sizing of wind–hydrogen systems by taking into account the local and regional resources, demands, constraints and opportunities. This study considers both the economic and technological variables and describes an optimisation method (OM) for analysing power systems in which part of the electricity generated by a grid-connected wind plant is used to produce hydrogen by electrolysis. An example application of this OM has been developed for a specific geographical area located in central Sicily. Our results identify the potential and the limitations connected to cases that use excess wind power to produce hydrogen for civil applications.

The paper discusses the rapid damping of pressure peaks in a water-hammer phenomenon after the end of a complete valve-closure maneuver. This effect is due to flow characteristics not considered when one-dimensional models are employed. Such an effect is linked to the cross-sectional velocity profiles, and therefore to the intrinsic two-dimensionality of the flow field. Applying a 2-D model, recently proposed in the literature, to expand the limited experimental data available with numerical results, useful information on the evolution of the velocity profiles during a transient has been obtained. Starting from an in-depth inspection of the terms in the momentum equation, an additional term is introduced to model the effects of the flow-field two-dimensionality in a 1-D formulation. Finally, the adequacy of a relationship previously proposed by the writers to evaluate the additional term is specifically showed for fast transients in the field of low-Reynolds-number flows when no cavitation occurs, even if its validity has been proven elsewhere for rather different conditions.

In recent decades, growing water demand and a scarcity of easily exploitable high-quality water sources has reinvigorated interest in the further development of already stressed groundwater resources. Since leakage reduction often means the acquisition of new high-quality water resources, utility managers are realizing that water loss must be considered in plans to extend water supply and leak detection is now perceived as a money-saving expense. Among leak detection methodologies, those based on transient analysis can be some of the fastest and cheapest. This article briefly outlines the properties of pressure waves in closed single pipe systems. Past findings from the analysis of pressure signals within the time domain framework are reviewed and time series of pressure variations acquired in laboratory experiments at one measurement section are examined. Emphasis is placed on the analysis of transient test results in the frequency domain and the use of the wavelet transform for interpreting pressure sig...

Partial blockages in water pipe networks may contribute to large energy dissipation throughout the system and reduce service effectiveness for customers. In this paper, a recently developed stochastic model using transients for detecting partial blockages in water pipelines is tested and numerical and experimental case studies are presented. The model is a stochastic successive linear estimator previously used in groundwater hydrology for detecting the heterogeneity pattern of the subsurface. The model estimates the distribution of diameters within a pipe with partial blockages and quantifies the uncertainty associated with these estimates. Results show that a first good estimate of the extent and size of the blockages can be obtained by a single test generated by the fast closure of a valve.

The aim of this study was to analyze energy, economic and environmental performances of a set of scenarios dealing with the production and the use of hydrogen as energy carriers in residential applications in combination with renewable energy (RE). The authors also made an investigation into the required economic conditions necessary for making H2–RE residential systems competitive with conventional ones, which are based on the use of grid electricity and natural gas. A case study was enacted in a small residential district in Palermo (Italy) made by five multi-storey buildings. Many energy systems have been considered according to several fuel-device combinations (electric grid, fuel cell, PV panels, wind turbines, boiler etc.). The software HOMER (hybrid optimization model for electric renewables), developed by NREL and Midwest Research Institute (USA), was used, in order to study the energy balance of the system and its components. Moreover, it was possible to simulate the hourly operation of each system and to calculate technical, economic and environmental performance parameters. The net present cost and the cost of energy are the two main parameters used to compare economic performances of the systems with both actual and expected costs in the medium term. A sensitivity analysis was carried out in order to appreciate the most important parameters influencing the economic performances of the systems and to define possible future scenarios of competitiveness between technologies. Emissions of CO2 (the most important greenhouse gas) and other pollutants have been considered for an environmental benefits analysis.

A technique is proposed for leak detection and evaluation in outfall pipes based on properties of transient pressure waves. Transients are caused by an increase of the piezometric head at the initial section of the outfall pipe. Since high overpressures are not necessary for the success of the technique and simple equipment is required, tests may be repeated periodically to check the state of the pipe. In order to verify the possibility of locating a possible leak on the basis of the results of transient tests, the effects of a leak on wave propagation from the numerical point of view are discussed first. A first-order formula for preliminary evaluation of the discharge behavior of the leak is also given. Results of some laboratory tests carried out on a long pipe are shown in order to confirm the reliability and validity of the proposed technique. Inverse transient calculations are proved to be able to provide precise information about the characteristics of the leak.

In most cases, the final configuration of complex pipe networks is attained simply by connecting subsystems initially designed to work separately. Thus, automatic control valves (ACV) are often installed in the confluence nodes where the subsystems meet. The present paper deals with the response and hydraulic behavior of ACVs, topics on which data are scarce. More precisely, attention is focused on transients, which occur in a water-distribution pipe system in operation due to the action of an ACV, both from an experimental and numerical point of view. The aim of the water-hammer field tests is to enlarge the amount of the experimental data concerning unsteady-state flow processes in operating pipe systems. The numerical model extends to field conditions and ACVs laboratory work on the hydraulic characterization of valves and the unsteady-state friction simulation.

Since 1991 “Computing and Control for the Water Industry – CCWI” is a well-established series of bi-annual meetings. On 2–4 September 2013, the 12th edition (CCWI2013) was held in Perugia (Italy) and was focused on Information for Water Systems and Smart Cities. CCWI2013 emphasized the integration between the more conventional themes of the analysis and planning of water systems and information technology. Such an integration offers opportunities for design solutions and innovative models for the challenging problems of water system management in an urban perspective, a key concept for smart cities (Brunone and Giustolisi, 2014). The large number of presentations – more than 200 with many young researchers from Europe and overseas – confirmed the interest for CCWI2013 themes and the increasing success of CCWI Conferences (Fig. 1). This CCWI2013 special issue contains a selection of extended CCWI2013 papers which give a taste of the Proceedings of the Conference published on Procedia Engineering Elsevier (www.sciencedirect.com/science/journal/ 18777058/70). In fact their topics range from sustainabilitybased indicators of the urban water systems (Behzadian et al., 2014), design and control parameters in water treatment (Ramphal and Sibiya, 2014), numerical simulation of the transition between surface and pressurized flow (Fernandez-Pato and Garcia-Navarro, 2014) to optimisation of pump and valve schedules in complex large-scale water distribution networks (Skworcow et al., 2014), and a real data-based model to simulate the behavior of a pumping station equipped with variable speed pumps (Capponi et al., 2014). Figure 1. Last nine editions of CCWI conferences: number of papers published in the proceedings (from Brunone and Giustolisi, 2014).

Variable speed pumps (VSPs) are widely used in water distribution systems (WDSs). They can increase the efficiency of the system and reduce the energy consumptions, when the functioning conditions move away from those used for the design. Affinity laws allow to model the characteristic curve of VSPs, in terms of dimensionless flow, head and power. Efficiency of the VSPs can also be predicted, although the effects of the variation in the rotation speed can be questioned. In this paper, the experimental data acquired by TeaAcque at the Mantova Casale pumping station are interpreted by means of the dimensionless equations derived by the affinity laws. The measured “wire to water” efficiency of the system is compared to the theoretical one.

Partial blockages in water pipe networks may contribute to large energy dissipation throughout the system and reduce the service effectiveness for the customers. In this paper, a recently developed stochastic model using transient head measurements for detecting partial blockages in water pipelines is tested with two experimental case studies. The model is a stochastic Successive Linear Estimator (SLE, Yeh et al., 1996) previously used in groundwater hydrology for detecting the heterogeneity pattern of the subsurface. The model provides statistically the best unbiased estimate of diameter distribution due to partial blockages and quantifies the uncertainty associated with these estimates. Tests were carried out at the Water Engineering Laboratory of the University of Perugia (WEL) on two high density polyethylene pipe systems. In the experiments the partial blockages were simulated by placing a smaller diameter pipe of two different lengths between the main pipe. Results show that a first good estimate of the length and the size of the blockage can be obtained by a single short duration transient test executed by maneuvering a ball valve located far away from the blockage position.

Due to the experimental evidence, in the last decades the leak law, i.e. the relationship between the system functioning conditions and the leakage, has been seriously questioned. Some corrections have been introduced in the classical orifice equation to take into account all the relevant parameters it depends on (e.g. leak shape, pipe material and thickness, ...). Even if a perfect law is derived for a single leak in a pipe still an open issue remains, that is the use of the same leak law for a whole network or district. In terms of practical applications, the link from a single leak outflow to a system leakage is relevant since it allows the transfer of the results from laboratory experiments to real systems –from the local scale of a single leak to the global scale of a district with several different leaks. In this paper the effect of the spatial variation of the leak law parameters at the local scale on leak law determination at a global scale are considered. Conclusions on the possible comparison between the laws at the two scales are given.

In this paper the possibility of using transients to survey a complex transmission system in the city of Mantova, Italy is explored. Transients are generated by pump trip, and the pressure signal is acquired immediately downstream of the pumping station. The pressure signal is analyzed by the wavelet transform to locate the main singularities and evaluate the pressure wave speed of the main pipe. Then a lagrangian model is carried out to evaluate the causes of experimental pressure variations. The comparison between experimental and numerical traces allows checking the efficaciousness of the procedure and diagnosing the network.

Pump speed, input power, pressure and discharge data are analyzed for evaluating functioning conditions of Casale pumping station in Mantova, Italy, managed by TeaAcque. A model based on the affinity laws is used to simulate the behavior of the installed variable speed pumps. Quadratic and cubic polynomial curves are used to fit the pump data given by the affinity laws. Such curves allow predicting the efficiency when the functioning conditions change. The relationship between the rotation speed and the efficiency is also derived.