Peter Chalk Centre

University of Exeter

Stocker Road

Exeter

EX4 4QD

Tel: +44 (0)1392 263637

E-mail: CCWI2019@exeter.ac.uk 

17th International Computing & Control for the Water Industry Conference

1st - 4th September 2019
University of Exeter, UK
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6B Demand, leakage, energy

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Green

Guangtao Fu

Chair:

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Effect of Hydraulic Transients on Leak Noise

Richard Collins

Presenter:

Authors:

Morbidelli, Provvisiero, Beck, Richard Collins and Ferrante

Detecting leaks is commonly undertaken using the noise that the leak creates as the water exits through the leak orifice. This sound is transmitted along the pipe and can be detected by accelerometers or hydrophones installed in the system. By correlating the measured signal from pairs of sensors it is possible to determine the difference in time of arrival, and therefore the relative distance to the leak. Combining this with knowledge of the speed of the transmission of the sounds waves allows the leak to be located. Whilst successful in many situations difficulties can arise with this technique in real systems, where the complexity of the systems can produce false positives, plastic pipes attenuate signals (particularly the high frequency components) and wavespeeds in the pipes are unknown. Hydraulic transients, fluctuations in the pressure and bulk velocity of the fluid in pipes that travel in waves around systems, have also been successfully used in the past to detect leaks, through the reflections generated as they pass leaks, or the attenuation effects they have on signals. This paper introduces the concept that the passing of a hydraulic transients will modify the noise that a leak generates, and this variability in the leak signal then provides additional information that, combined with the measurement of the transient signal, can aid in locating the leak to a higher accuracy and also provide additional characterisation of the leak (size, shape etc.).

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Leakage Calibration in Water Distribution Networks with Pressure-Driven Analysis

João Muranho

Presenter:

Authors:

João Muranho, Ana Ferreira, Abel Gomes, Joaquim Sousa and Alfeu Sa Marques

Water distribution networks (WDN) connect consumers to the water sources, and its goal is to fulfil water demand. However, it is a well-known fact that WDN have losses and an important part of them occur at pipe level. Despite all the research efforts focused on this subject, the identification of leaky pipes is still a major challenge. EPANET is frequently used to simulate WDN’ models, using a link-node formulation, similar to a graph, where the water demands are assigned to the nodes. A linearized system of equations (mass and energy conservation laws) is iteratively solved by a Newton-Raphson algorithm. The EPANET is demand-driven, since it assumes the water pressure is always enough to satisfy the demands. However, on real WDN, states of insufficient pressure also occur. Besides that, the demand-driven approach is not suitable for pipe leakage simulation, which depends on the pressure. WaterNetGen — an EPANET extension— allows both demand and pressure driven simulations, including pipes’ leakage modelling. However, the leakage parameters (bursts and background leakage coefficients and exponents) must be set manually by an expert — manual calibration — for the whole network or for each pipe. This work proposes a calibration methodology to estimate the pipe background leakage parameters. The approach is tested on a set of synthetic models, generated by WaterNetGen, and then applied to a real WDN to assess its performance on real world conditions.

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Mass-balance calibration of WDN hydraulic models for designing leakage management actions

Luigi Berardi

Presenter:

Authors:

Luigi Berardi, Carloalberto Simone, Francesco Gino Ciliberti, Antonietta Simone, Daniele Biagio Laucelli and Orazio Giustolisi

Leakages from water distribution networks (WDN) represent a major management issue for water companies since they are related to losses of water and energy resources, increase the deterioration rate and expose citizens to increasing risk of insufficient/intermittent water supply. Technical literature classifies real water losses from WDNs as burst and background leakages. Some leakage management actions like the design of District Metering Areas (DMA), pressure management or rehabilitation works aim at reducing real losses that have major impacts in terms of lost water volume. Such volumetric losses encompass small background outflows and unreported leaks, whose location is unknown and depend on pressure. In this context, hydraulic models represent invaluable tool to support planning of management actions since they can simulate various alternative scenarios before implementing actions. Recent advancements in WDN hydraulic modelling allowed to move from classical demand-driven analysis (DDA), mainly conceived for design purposes, to pressure driven analyses (PDA), oriented at DN management. PDA computes water supplied to customers and leakage outflows as functions of pressure, enabling hydraulically consistent simulation of system behavior under normal or pressure-deficit conditions. Based on this, such WDN models include additional parameters with respect to classic DDA, such as the parameters of the pressure-leakage models, that need to be calibrated based on field information. Unfortunately, in many real circumstances, water companies are in the process of designing the monitoring of flow and pressure, and the only available data is the total inflow in the network and the estimate of real losses based on global water balance. In these cases, a reliable design model is needed to support various strategic activities such as DMA design and leakage reduction actions. This contribution presents a pragmatic approach to calibrate the design model which is based on introducing technical insight on deterioration phenomena within a mass-balance paradigm.

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Diagnosis of the water distribution system of Milan by means of transients: preliminary results

Marco Ferrante

Presenter:

Authors:

Chiara Adriani, Davide Bartocci, Daniele Belli, Benedetta Busti, Marco Ferrante, Serena Fracchia, Teresa G.E. Gentile, Fabio Marelli, Elisa Morbidelli, Fabrizio Provvisiero and Massimiliano Vidiri

Some preliminary results are presented, obtained by transient tests carried out to assess the pipe conditions of DN 500 and DN 600 steel trunks of the water distribution system of the city of Milan, Italy, managed by MM s.p.a. During each test the pressure waves were generated at one section and the variations in time of the pressure, or pressure signals, were acquired at three measurement sections by means of piezoresistive pressure transducers. The data acquisition systems were synchronized by means of GPS receivers. The detection of the arrival times of the pressure waves at the measurement sections are used to detect and locate singularities in the network, which can correspond to damages to pipes and valves. Furthermore, since the value of the wave speed is related to the pipe diameter and thickness, the evaluation of different wave speed in similar trunks can suggest a different degradation, leading to the assessment of the actual pipe conditions before the leakage. The specific problems related to the diagnosis by transient tests of a water distribution system are also discussed.

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A Living Laboratory for Water Demand Management

Peter Melville-Shreeve

Presenter:

Authors:

Peter Melville-Shreeve, Alex Newman, Hossein Rezaei and David Butler

Water-flushed toilets represent one of the major consumers of potable water in both domestic and commercial environments, accounting for up to 90% of consumption in non-residential buildings and 35% in residential properties. In recent years there has been a paradigm shift in the design of toilets and other washroom assets. One such solution is the ultra-low flush toilet (ULFT) from Propelair®. This toilet uses a novel ‘displaced air’ flushing principle which, unlike traditional solutions, disconnects flush performance from the volume of water involved. Propelair® toilets include a lid which, when closed, creates a seal. When the flush is triggered water enters the pan to clean it followed by air from a proprietary pump which forces everything from the pan, the sealed lids prevents any escape of air. This combination of water and displaced air provide the motive force for pan clearance. More water is then released to fill the trap. The flush cycle uses 1.5 litres of water, a reduction of 75% compared to a standard 6 litre flush from a traditional toilet. A trial of the ULFT systems has seen the installation of over 100 units in 44 washrooms across 7 buildings. This study reports the water savings at two washrooms with a variety of water efficient features, and investigates data from a large-scale living laboratory study. As the trial progresses, further data will be analysed in order to extract other information which will be useful in assessing the costs and benefits of water efficiency measures in non-residential washrooms and planning for water demand management needs of the future.

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Inferring Network Demands from Transient Pressures

Richard Collins

Presenter:

Authors:

Richard Collins and Ehsan Kazemi

People have increasingly been aware that our water distribution systems are more dynamic than traditionally thought. The advances in cheap pressure measurement rates and accuracy have enabled people to see the true size and number of hydraulic transients that pass through live pipeline systems.This increase in awareness has been mirrored by an increase in worry of the damage that transients are/could be doing to the system through inducing leaks and damaging pipeline furniture. Transients also have the potential for being a wonderful tool to collect information about the systems. Transients are modified by all the features they pass, the reason they are hard to predict and model in real systems, but this means they contain useful information if they can be suitably decoded. This paper explores the ability of statistical inference techniques to infer boundary conditions of transient models and demonstrates the technique by predicting varying customer demands, and leak flows in a small scale simulated water distribution network.

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