Rehabilitation in Intermittent Water Distribution Networks for Optimal Operation

Equitable distribution of water is a growing source of worry, and concerns water systems’ managers as water-stressed areas steadily increase and situations of water scarcity are becoming more frequent. The problem goes beyond just the water sector and globally affects many countries’ economies since water resources have multiple uses (i.e., power generation, irrigation, etc.). One of the various strategies to overcome periods of extreme events (e.g., water scarcity) is the adoption of intermittent operation. Intermittent operation can minimize water losses, and manages to supply the same water demand (in terms of volume) during a reduced period of time. However, despite minimizing water losses, the energy consumption necessary to cope with the increased flows and head loss, due to the reduced number of operating hours, increases. This paper explores a strategy based on rehabilitation of the system’s main pipes. It also considers optimal selection and scheduling of pumps aiming at improving the system’s hydraulic parameters (e.g., velocity and head losses) and at reducing the operating costs. Both selection and scheduling of pumps and resizing of main pipes are optimized using Particle Swarm Optimization. The obtained results show that this strategy can significantly reduce the energy consumed and can be economically feasible.

Evaluation of Effectiveness of Waterjet Propulsor for a Small Underwater Vehicle

The goal of the project described is to replace the existing propulsion system of a small underwater vehicle with a solution less prone to mechanical damage and ensuring a lower risk of the entanglement of fibrous objects suspended in the body of water. Four typical marine screws are utilised in the current design of the vehicle. One possible solution of the problem is the application of waterjet propulsors located inside the body of the vehicle instead. The general condition of the application of the new solution was to secure at least the same motion control capabilities of the vehicle while the basic capability is its propulsion effectiveness at the required speed. Specific features of the considered waterjet propulsor, when compared with their application in surface vessel propulsion, are the lack of the head losses and the low significance of cavitation issues. One of the difficulties in the considered case is the small diameter of the propulsor in comparison to commercially available waterjet units, which have diameters between 0.1 [m] and 1.0 [m]. There is very little data regarding the design and performance of devices in the 0.02 to 0.05 [m] range. Methods utilised to forecast the performance of the new propulsion system are presented and results compared. These were semi-empirical calculations, numerical calculations and tests of real devices. The algorithm that is based on semi-empirical calculations is of particular interest while it offers possibility quick assessment of performance of a propulsor composed of several well defined components. The results indicate the feasibility of modification of the propulsion system for the considered vehicle if all the existing circumstances are taken into account.

Comparison and Validation of Models for the Design of Optimal Economic Pipe Diameters: A Case Study in the Anseba Region, Eritrea

An optimal design for a pressurized flow pipe network is characterized by being economical and contributing the least amount of losses during water transmission through the system. The diameter of a pipe in a network system that delivers the desired effect with the minimum amount of waste and expenses is referred to as an optimal pipe size. The Life-Cycle Cost Analysis (LCCA) model is widely recognized as the recommended standard technique to estimate the optimal pipe size for any pipe flow network system. Numerous empirical formulas have been proposed to simplify the computations required in this economic analysis model. This study seeks to compare the various empirical models that have been proposed by different authors based on a variety of physical variables involved in fluid flow dynamics. Eleven different empirical equations were chosen in order to select the optimal diameter for the network at the Hamelmalo Agricultural College farm located in the Anseba region of Eritrea for the distribution of water to the different sub-plots. The estimated diameters were compared to the standard diameter calculated using the standard LCCA method. This comparison was based on the estimated total head losses and economic analysis of the pipe diameters chosen for such network. Moreover, a statistical analysis was conducted to obtain the best-fit recommended modeled diameter for the network. The Bresse’s model performance was the most adequate when compared with the LCCA model.

ANALISIS PENGARUH PERUBAHAN KATUP PADA PIPA GALVANIS DAN STAINLESS TERHADAP KERUGIAN HEAD

Kehilangan energy merupakan factor yang mempengaruhi kapasitas pipa sebagai sarana penghantar aliran, baik air maupun minyak.Kehilangan energy menyebabkan terjadinya pengurangan debit aliran. Tujuan dari penelitian ini adalah untuk mengetahui perbandingan besaran kerugian head (major losses) fluida galvanis dan stainless dan kerugian head (minor losses) fluida pada alat bantu sambungan galeu valve,sambungan tee dan lbow. Metode yang digunakan dalam penelitian ini yaitu metode analisis data dilakukan dalam 2 tahap pengujian head losses, head mayor losses dan minor losses. pengujian dilakukan 3 variasi debit aliran yang nilainya di sesuaikan dengan bukaan katup. Hasil analisis head losses dari reservoir ke pipa distribusi di dapat kehilangan tekanan akibat pergeseran antara dinding pipa dengan fluida (mayor losses), untuk pipa galvanis dengan faktor gesekan dalam pipa dari pembukaan katub pertama (1.157) kedua (1.282) ketiga. Sedangkan untuk kerugian head pada alat bantu pipa (minor losses) galve valve,sambungan tee,dan lbow dengan faktor kerugian yang di hasilkan untuk paling besar terdapat pada sambungan tee dengan hasil setiap pembukaan katub pertama (75.91) kedua (71.17) ketiga (66.42) Dan faktor kerugian pada Galve valve menghasilkan dari pembukaan katub pertama (71.17) kedua (56.94) dan ketiga (42,69) dan paling terendah ada pada lbow dengan hasil nilai dari pembukaan katub pertama kedua (61.67) kedua (68.80) ketiga (75.91).Dari hasil penelitian ini dapat di simpulkan bahwa kerugian head (mayor losses) pada pipa galvanis dan stainless. untuk pipa galvanis lebih besar tingkat kerugiannya di banding pipa stainless.Sedangkan pada alat bantu pipa (minir losses) nilai kerugian terbesar pada sambungan tee,kemudian galeu valve dan yang paling kecil pada lbow.

Protection and Guidance of Downstream Moving Fish with Electrified Horizontal Bar Rack Bypass Systems

Horizontal bar rack bypass systems (HBR-BS) are characterized by a horizontal bar rack (HBR) with narrow clear bar spacing of 10–20 mm and an adjacent bypass (BS) to efficiently protect and guide downstream moving fish at water intakes. The small bar spacing may lead to operational challenges, such as clogging and high head losses. This study investigated whether combining an HBR with a low-voltage electric field (e-HBR) allows one to increase the clear bar spacing while maintaining a high standard of fish protection and guidance efficiency. To this end, an HBR-BS with 20 mm bar spacing and an e-HBR-BS with 20 and 51 mm bar spacing were tested with spirlin (Alburnoides bipunctatus) and European eel (Anguilla anguilla) in a laboratory flume. The racks were electrified with 38 V pulsed direct current. The protection efficiency of the e-HBR with 51 mm was 96% for spirlin and 86% for eels, which are similar results to those of the HBR with 20 mm. Some eels passed through the e-HBR, but only when they were parallel to the rack. Fish injuries of variable severeness due to the electrification were observed. The results highlight the potential of hybrid barriers for the protection of downstream moving fish. However, fish injuries due to electricity may occur; and reporting applied voltage, electrode geometry, resulting electric field strength and the pulse pattern of the electrified rack setup is necessary to ensure comparability among studies and to avoid injuries.

Basics of Calculation and Design of Two-Column Two-Filter Water Intake Wells

The paper provides an overview of the known designs of water wells. A new design of a two-column two-filter water intake well has been also proposed, in which the filters are arranged in two tiers. This will lead to an increase in water intake capacity and will reduce the filtration rate on the approach to the filters. This, in turn, will create conditions for reducing head losses and will make it possible to reduce drawdowns in the well, ensuring a reduction in the cost of produced water. This design combines both working and reserve wells located in one borehole, which increases its reliability, durability and uninterrupted water supply to the consumer. A method for calculating the hydraulic parameters of a two-column two-filter water intake well is presented in the paper. It is based on dependencies for calculating the main geometric dimensions for a given design flow rate and hydrogeological characteristics of an aquifer, as well as formulas for determining a decrease in a well for a given period of operation when one and two pumps operate simultaneously. The basics of designing a well of the proposed design are outlined in the paper. The paper considers an example of calculation for a new well design instead of an existing typical well that has reduced its specific flow rate.

Technical regulation for the values of hydraulic parameters of used metal pipes in order to extend the period of their use

Objective: To compare the characteristics of hydraulic potential in worn steel pipes with internal deposits subjected to cleaning by mechanical and chemical methods. Methods: Calculated dependencies are used for hydraulic calculation of new metal pipes and pipes with internal deposits. Results: A calculated dependence was obtained to determine the value of the inner diameter of pipes with any thickness of the layer of internal deposits. The concept of an efficient pipeline is introduced and a comparison made of the values of head losses in new pipes and in pipes with internal deposits. A specific practical example is considered. For the given example, compare the values of energy consumption of pumping equipment for two methods of cleaning the inner surface of pipes. Measures are indicated to ensure the efficiency of operation of water supply networks. Practical importance: It is shown that the chemical method of technical regulation of the hydraulic characteristics of new steel pipes provides an extension of the period of their further use.

Features of hydraulic calculation of marine vacuum fish pumping units

Цель статьи – модифицировать ранее разработанный метод гидравлического расчета вакуумной перекачивающей системы для течения в рыбонасосной установке, работающей на промысловом судне. Динамика откачивания и закачивания воздуха в буферную емкость не изменилась. Анализ экспериментальных данных показал, что гидравлические потери по длине трубопровода прямо пропорциональны величине массовой доли рыбы. В судовых условиях потери напора в местных гидравлических сопротивлениях могут иметь тот же порядок, что и потери по длине. В отличие от традиционных судовых систем течение жидкости в вакуумных рыбонасосных установках (ВРУ) является нестационарным из-за увеличения давления в буферной емкости, как на этапе всасывания, так и на этапе вытеснения. Что приводит к необходимости совместного решения уравнения Бернулли для нестационарных течений совместно с дифференциальными уравнениями для давления и объема жидкости в буферной емкости. Увеличение длины трубопровода или перепада высот приводит к снижению скорости движения водорыбной смеси и увеличению давления в буферной емкости. Как следствие, возрастает продолжительность цикла работы ВРУ и падает производительность. The purpose of the article is to modify a previously developed method of hydraulic calculation of a vacuum pumping system for a flow in a fish pump unit operating on a fishing vessel. The dynamics of pumping out and pumping air into the buffer tank did not change. Analysis of experimental data showed that hydraulic losses along the length of the pipeline are directly proportional to the value of the mass fraction of fish. In shipboard conditions, head losses in local hydraulic resistances can be of the same order as length losses. In contrast to traditional ship systems, the fluid flow in vacuum fish pumping units (VFP) is unsteady due to an increase in pressure in the buffer tank, both at the stage of suction and at the stage of displacement. This leads to the need of jointly solve the Bernoulli equation for unsteady flows together with differential equations for the pressure and volume of fluid in the buffer tank. An increase in the length of the pipeline or the height difference leads to a decrease in the speed of movement of the water-fish mixture and an increase in pressure in the buffer tank. As a result, the duration of the VFP operation cycle increases and the productivity decreases.