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Although pressure reducing valves (PRVs) have traditionally been employed to regulate pressure and reducer water leakage, researchers have been increasingly investigating the strategy of micro-hydropower generation using pumps as turbines (PATs) to enable both pressure reduction and energy production as an alternative strategy in water distribution networks (WDNs). However, due to the continuous variability of flow discharge during the day, selecting the optimal PAT remains a challenging issue. To address this, the authors have developed HYPER, a freely available software app that implements an innovative approach for selecting the most suitable PAT in systems that involve both hydraulic and/or electrical regulation. In enabling the identification of the PAT parameters that maximize energy production, HYPER thus provides a fast and effective PAT selection tool. The effectiveness of the proposed approach was further demonstrated with application to a real WDN. Four operational patterns varying in terms of available flow and head drop were considered, showing that the most efficient pumps consistently tended to be located in close proximity to the maximum produced energy. Furthermore, the results confirmed that hydraulic regulation and coupled hydraulic/electric regulation-based installation layouts represent the best solutions in terms of energy produced. The solely electrical regulation option, given its poor flexibility, returns in all cases lower energy production with the lower adaptability of commercial pumps. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

One of the main issues arising during the rapid filling of a pipeline is the pressure transient which originates after the entrapped air has been expelled at the air release valve. Because of the difference in density between water and air, a pressure transient originates at the impact of the water column. Many authors have analyzed the problem, both from the theoretical and the experimental standpoint. Nevertheless, mainly vertical or horizontal pipelines have been analyzed, whereas in real field applications, the pipe profile is a sequence of ascending and descending pipes, with air release/vacuum valves at high points. To overcome lack of knowledge regarding this latter case, laboratory experiments were carried out to simulate the filling of an undulating pipeline, initially empty at atmospheric pressure. The pipe profile has a high point where an orifice is installed for air venting, so as to simulate the air release valve at intermediate high point of a supply pipeline. In the experiments, the diameter of the orifice and the opening degree of both upstream and downstream valves were varied, in order to analyze their effect on the pressure transient. The experiments were also carried out with a longer descending pipe, in order to assess the effects on the pressure surge of the air volume downstream of the orifice. [ABSTRACT FROM AUTHOR]

The one-dimensional (1D) power law velocity distribution, commonly used for computing velocities in open channel flow, has been derived empirically. However, a multitude of problems, such as scour around bridge piers, cutoffs and diversions, pollutant dispersion, and so on, require the velocity distribution in two dimensions. This paper employs the Shannon entropy theory for deriving the power law velocity distribution in two-dimensions (2D). The development encompasses the rectangular domain, but can be extended to any arbitrary domain, including a trapezoidal domain. The derived methodology requires only a few parameters and the good agreement is confirmed by comparing the velocity values calculated using the proposed methodology with values derived from both the 1D power law model and a logarithmic velocity distribution available in the literature. [ABSTRACT FROM AUTHOR]

Velocity distribution in an open channel flow can be very useful to model many hydraulic phenomena. Among the others, several 1D models based on the concept of entropy are available in the literature, which allow estimating the velocity distribution by measuring velocities only in a few points. Nevertheless, since 1D models have often a limited practical use, a 2D entropy based model was recently developed. The model provides a reliable estimation of the velocity distribution for open channel flow with a rectangular cross section, if the maximum velocity and the average velocity are known. In this paper results from the proposed model were compared with measured velocities carried out from laboratory experiments. Calculated values were also compared with results inferred from a 2D model available in the literature, resulting in a greater ease of use and a more reliable estimate of the velocity profile. [ABSTRACT FROM AUTHOR]