جستجوی مقالات مرتبط با کلیدواژه « Pressure » در نشریات گروه « مهندسی آب »

Water loss is a significant issue that leads to substantial damage to water resources, civil infrastructure, the environment, and water distribution companies. Urban water supply networks, particularly in regions with scarce water resources, face challenges related to water loss. Leakage from these networks constitutes a major portion of the overall water loss. Factors contributing to leakage include the aging of water supply systems, pipe damage due to soil stresses and urban traffic, fluctuations in water pressure, improper urban plumbing practices, and inadequate embankments. Examining factors such as pressure, pipe type, soil environment, and temperature can help identify the causes of leakage and effectively manage and mitigate its volume. Laboratory and field investigations have revealed that the leakage power, contrary to the pressure-leakage relationship, falls within the range of 0.5 to 2.79, with values exceeding 0.5 due to variations in pipe types, dimensions, and the type of cracks. Reducing the D50 (median grain size) of the soil and selecting an appropriate soil granulation around the pipes can effectively reduce the leakage flow rate. This article provides an overview of water wastage, its types, and underlying causes, followed by a discussion on the fundamentals of leakage calculation.

Water consumption in agriculture, increasing irrigation efficiency, and reducing water consumption against the constant yield of the crop are very important. Therefore, the study of water consumption efficiency in different irrigation methods has a significant role in the macro-agricultural and industrial planning of the country. In the present study, the efficiency of gravity irrigation systems (channelet), low pressure, and pressure irrigation in the lands north of Karkheh Khuzestan (arayez 2&3 project) has been investigated. The results showed that the irrigation efficiency in the pressurized irrigation method was the highest so the total efficiency in the pressurized irrigation system is 64.2% higher than channelet irrigation and 55.8% higher than low-pressure irrigation. Also, irrigation efficiency in low-pressure irrigation methods is about 5.3% higher than in channelet irrigation. Economical studies and analysis of different irrigation systems showed that although the initial cost of setting up a pressurized irrigation system is higher than gravity and low-pressure irrigation, in a long time, it will be economically viable while the return on investment in this project is maximum 5 years.

Pressure management is an efficient and inexpensive way to reduce leakage in water distribution networks, which is usually possible by systematical operation of valves, pumps, reservoirs, and tanks. In water distribution networks, there are many valves only used during the repairs in the time of accidents. In this paper, a simple approach is proposed for managing pressure and leakage in networks with optimal scheduling of the existing valves’ operation. For this purpose, the optimal locations of the valves are determined by using the valve selection index and their opening rate has been optimized in the minimum, medium and maximum consumption conditions. The optimization was done by combining particle swarm and ant colony optimization algorithm and EPANET simulator within the framework of MATLAB. The proposed method is performed both on a sample and the real network. The results show that there is a significant improvement in the performance of both networks in the average and maximum consumption conditions, so that, the reliability of the Maragheh city network is improved by 22 and 24 percent and leakage by 31 and 20 percent, respectively, compared to the base model. In general, using this approach can improve the performance of real networks by manual programming of a number of selected valves.

Considering the importance of sufficient pressure in supplying demand in water distribution networks, it is necessary to study the factors affecting pressure variation, that the roughness of pipes directly affects the pressure of nodes. Therefore, the study of factors affecting the change in roughness coefficient (Hasen-Williams) in water distribution networks is important. Pipes diameter, age and corrosion are among factors affecting the change in the roughness coefficient of pipes that are evaluated in this paper. The roughness coefficients were plotted against each of the above mentioned factors, and the approximate relations of the roughness coefficient was obtained by fitting to the obtained graphs. Finally, by combining the relations obtained, a general relation is obtained for the roughness coefficient. Also, in this paper, the cast iron pipes, for which laboratory data is available, were used to obtain a mathematical relationship.Then again, instead of using the roughness coefficient of new pipes in analysis and design, the roughness coefficient for the end of the design period was used, taking into account the effective factors mentioned.To evaluate the results of the proposed method, a two-loop network was investigated in two common and real situations. The results showed that if the roughness coefficient of new pipes at the end of design period is used for designing, there will be a save of about 50% in cost of pipes, but then the network pressure at the end of design period will be reduced by more than 25%. Therefore, in order to ensure that there is sufficient pressure and demand satisfaction throughout the design period, it is necessary to accept an increase in the cost of network implementation at the beginning of the project.