Loading...
5 results
Search Results
Now showing 1 - 5 of 5
- Optimal location and setting of time modulated PRVs for water loss reduction with leakage modelling by pressure driven analysisPublication . Sousa, J.; Muranho, João; Sá Marques, Alfeu; Gomes, RicardoWater losses have economical, technical, social and environmental negative impacts and so water companies are always willing to reduce them. The IWA Water Loss Task Force identified four main control strategies to reduce real losses: 1) infrastructure management; 2) pressure management; 3) active leakage control; and 4) speed and quality of repairs. Unreported leaks and background leakage usually represent a major component of water losses and pressure management is an effective, easy, economic and quick solution to reduce it. Pressure management can be implemented by introducing Pressure Reduction Valves (PRVs): fixed-outlet; time-modulated; flow-modulated and pressure modulated. For a fixed-outlet PRV there is a single working condition (pressure downstream of the PRV is always the same). For a time-modulated PRV there can be several working conditions (for instance, a lower pressure during the night period - from 0 to 6 am, and higher one during the remainder of the day). The flow-modulated and pressure modulated PRVs are more efficient because they constantly try to adjust the working conditions to reach the minimum pressure required at the critical node. However, pressure management projects must be preceded by specialized studies (identify the optimal location and settings of the PRVs to install) and cost benefit analysis (assessment of economic viability). A previous work presented a methodology to help in those tasks, by identifying the optimal location and setting of fixed-outlet PRVs to reduce water losses in WDNs and maximize the NPV of pressure management projects. Now the methodology was extended to include also time modulated PRVs and this paper presents the results obtained for a hypothetical case study.
- Optimal District Metered Area Design by Simulated AnnealingPublication . Gomes, Ricardo; Sousa, J.; Marques, Alfeu Sá; Muranho, JoãoWater losses reduction in Water Distribution Systems (WDSs) is nowadays an issue of growing importance for water companies to ensure the economic sustainability of these public services. In this context, the implementation of District Metered Areas (DMAs) and/or pressure management are considered effective tools for leakage control, particularly in large networks and in systems with deteriorated infrastructures and with high pressure. Based in previous studies performed by the authors (Gomes et al., 2012; Gomes et al., 2015; Sousa et al., 2015), the methodology described in this paper follows the ‘water losses management international best practices’ and makes it possible to evaluate the Net Present Value (NPV) of DMAs project, as well as the benefits that can be achieved by pressure management in WDS, particularly in terms of water production reduction. Leakage assessment is performed using the analysis of the minimum night flow and the FAVAD concept, and it uses a pressure driven simulation model to predict the network hydraulic behaviour under different pressure conditions. The optimal location of DMAs entry points, pipes reinforcement/replacement and locations/settings of the Pressure Reduction Valves (PRVs) are identified by a Simulated Annealing algorithm. The potential of this methodology is illustrated through an hypothetical case study.
- Localização e regulação ótimas de válvulas redutoras de pressão em redes de distribuição de águaPublication . Sousa, J.; Muranho, João; Sá Marques, Alfeu; Gomes, RicardoNos últimos anos tem-se observado uma crescente preocupação por parte das entidades gestoras (EG) com o controlo das perdas de água em redes de distribuição de água (RDA). Provavelmente a maior parcela das perdas de água deve-se a fugas não reportadas, sendo apenas identificadas através da implementação de estratégias de controlo ativo de perdas (CAP). Porém, este tipo de estratégia implica a existência de equipamentos específicos e recursos humanos especializados, que, infelizmente, não estão ao alcance de todas as entidades gestoras. A gestão da pressão (GP) surge neste contexto como uma possível alternativa (ou complemento) ao CAP. Nesta comunicação apresenta-se uma ferramenta informática desenvolvida para apoiar o desenvolvimento de projetos de GP. A ferramenta tem por base um modelo de simulação da RDA, em que as fugas são modeladas como dependentes da pressão, e um modelo de otimização cujo objetivo é maximizar o benefício da implementação da GP (diferença entre benefícios e custos), do que resulta a identificação das melhores localizações para instalar válvulas redutoras de pressão (VRP) e as respetivas pressões à saída. A aplicação desta metodologia é demonstrada através de um exemplo hipotético que serve para ilustrar a facilidade de utilização e as suas potencialidades.
- Optimal District Metered Area design by Simulated AnnealingPublication . Gomes, Ricardo; Sousa, J.; Sá Marques, Alfeu; Muranho, JoãoWater losses reduction in Water Distribution Systems (WDS) is nowadays an issue of growing importance for water companies to ensure the sustainability of these public services. In this context, the implementation of District Metered Areas (DMAs) and/or pressure management are considered the most effective tools for leakage control, particularly in large networks and in systems with deteriorated infrastructures and with high pressure. Based in previous studies performed by the authors [1,2,3], the methodology described in this paper follows the ‘water losses management international best practices’ and makes it possible to evaluate the Net Present Value (NPV) of DMAs project, as well as the benefits that can be achieved by pressure management in WDS, particularly in terms of water production reduction. It is based on the analysis of the minimum night flow and the FAVAD concept, and it uses a pressure driven simulation model to predict the network hydraulic behaviour under different pressure conditions. Leakage assessment is performed using pressure driven analysis and the optimal location of pipes reinforcement/replacement and settings of the Pressure Reduction Valves (PRVs) are identified by a Simulated Annealing algorithm. The potential of this methodology is illustrated through an hypothetical case study.
- Water Distribution Network Reliability: are Surrogate Measures Reliable?Publication . Muranho, João; Sousa, J.; Marques, Alfeu Sá; Gomes, RicardoWater distribution networks (WDNs) must be reliable infrastructures since they provide an essential service to society. Reliability assessment is a complex task and involves various aspects: mechanical, hydraulic, water quality, water safety, among others. This paper focus is on the hydraulic reliability. Hydraulic reliability is computationally hard to measure directly, therefore researchers came up with surrogate measures, like the resilience index, the modified resilience index, the flow entropy or the diameter-sensitive flow entropy, that are simple and fast to compute. But, are these surrogate measures reliable to be used in the design of WDNs? This paper proposes a new reliability index based on the surplus flow available on each node to mitigate the effects of a pipe failure. To illustrate the applicability of this new index, a WDN example is optimally designed (simulated annealing algorithm embedded in WaterNetGen) in order to maximize some reliability index subject to a given budget. Results show that the solutions based on the flow entropy or the proposed index are more reliable than the others, and, also, the maximization of the other reliability indexes gives only a residual contribution to the global reliability (or even no contribution at all).