Study of changes in the coefficient of hydraulic friction of materials of pressure pipes at different temperatures

Summary

Reducing the cost of electricity for the mechanical transportation of water through pressure pipelines by reducing the hydraulic resistance of the inner walls of the pipes is of current importance. This circumstance predetermines the need for appropriate hydraulic testing of alternative materials that can be used in the design and construction of pipeline systems. The aim of the study is to identify the nature of the change in the value of hydraulic friction depending on the temperature conditions of the transported water and the environment in certain ranges, with the subsequent possible control of the transportation process with a minimum of energy costs. The set goals are achieved by experimental computational and analytical approaches to determining the dynamics of changes in the hydraulic parameters of pipelines made of various materials. A comprehensive analysis of the experimental and calculated data obtained using patented automated systems for determining the coefficients of hydraulic friction for a polyethylene pipe and a pipe made of unplasticized polyvinylchloride, and the dynamics of changes in these coefficients depending on the temperature of the transported water and the temperature conditions of pipeline laying is presented.

Key words

pressure pipeline , hydraulic resistance , electrical energy consumption , temperature conditions , computerized calculations

Potentialities of energy saving in the operation of a sanitation system of a big city

Summary

The article, without mathematical formalization, with due consideration of physical interpretations of the process of wastewater disposal in a large city, reveals the potential for energy savings in the process of wastewater transportation in an extensive gravity network, enclosed in its very structure. This potential can be fulfilled through targeted operational redistribution of wastewater flows over sewage pumping stations and transportation mains of the network, achieving the minimum of total energy consumption by all pumping stations. It is shown that the calculation of such a redistribution is possible only on the basis of a mathematical model of the project by formulating and solving the corresponding optimization problem. The requirements that the mathematical model of the project shall meet are discussed; and its capabilities are shown while operating the network not only in normal operating conditions but also in emergency situations. The consideration of the problem is based on the positive results of a large-scale industrial experiment conducted earlier on the optimal management of a section of the Moscow sanitation system.

Key words

sewerage pumping station , water disposal system , specific features of the sewer network structure , electrical energy consumption , redistribution of wastewater flows , mathematical model of the project , optimization task

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