Using Statistical Analysis to Examine the Relationship between Hydraulic Characteristics and Pipe-Level Energy Performance

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Authors
Hashemi, Saeed
Keyword
Water Distribution Systems , Energy Metrics , Energy Efficiency , Pipe Leakage , Head Loss
Abstract
Energy efficiency has been a long standing issue faced by municipal managers when dealing with water distribution systems as these systems are energy intensive. Perhaps energy in per se is one of the most widely used indicators in identifying how well a distribution network is running. This study brings the idea of energy auditing from the network level to the pipe level by means of a set of novel energy metrics. This way once analysed a system would merit values for each pipe which helps to distinguish low from high-efficiency pipes in large networks. The originality of this work is guaranteed by examining the energy dynamics of pipes across 18 systems in North America including over 40,000 pipes, ensuring the diversity of characteristics and the statistical significance of findings. Multivariate statistical analyses including correlation, regression and Principal Component Analysis (PCA) are employed to find relationships between energy metrics and hydraulic factors. Also, common practice unit headloss thresholds as well as replacement approaches are put into perspective from an energy standpoint. Energy efficiency has been a long standing issue faced by municipal managers when dealing with water distribution systems as these systems are energy intensive. Perhaps energy in per se is one of the most widely used indicators in identifying how well a distribution network is running. This study brings the idea of energy auditing from the network level to the pipe level by means of a set of novel energy metrics. This way once analysed a system would merit values for each pipe which helps to distinguish low from high-efficiency pipes in large networks. The originality of this work is guaranteed by examining the energy dynamics of pipes across 18 systems in North America including over 40,000 pipes, ensuring the diversity of characteristics and the statistical significance of findings. Multivariate statistical analyses including correlation, regression and Principal Component Analysis (PCA) are employed to find relationships between energy metrics and hydraulic factors. Also, common practice unit headloss thresholds as well as replacement approaches are put into perspective from an energy standpoint. Chapter 3 introduces a set of pipe-level energy metrics and shows how location and flow intensity (as a result of diurnal changes of demand) can affect energy metrics in pipes. Technical Chapter 4 illustrates that energy indicators such as Net Energy Efficiency (NEE) and Energy Lost to Friction (ELTF) would be driven by average unit headloss. Subsequently, using regression analysis mathematical relationships between unit headloss and the two metrics of NEE and ELTF are explored to assess common-practice unit headloss thresholds as well as stricter ones, regarding efficiency. Stricter levels of NEE and ELTF energy based upon thresholds of unit headloss are expected, though at high cost. PCA results in technical Chapter 5 reveal relative importance of hydraulic parameters in energy efficiency. Also, some factors such as diameter and CHW are not as key as typically expected by water utilities in earmarking low-efficiency pipes. Further, efficiency as a missing link in common-practice replacement approaches can add value to bigger asset management landscape.
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