Effect of Skeletonization on Energy Consumption of Water Distribution System

A skeletonized water distribution system (WDS) model plays an important role in decision making process for its design and operations in planning phase. Given energy is the main driving force to operate a WDS efficiently and with the recent hikes in energy price, the investigation of energy flow in WDS is much more important than ever before. While a skeletonized network is easy to handle and takes less amount of time to run, it should represent the real-world scenario including the demand and hydraulics as accurately as possible. Failure to represent real-world scenario can mislead design and operational decisions including energy consumptions and delivery pressure. The purpose of this paper is to investigate how the energy flow in a WDS varies with the extent of the skeletonized network. Keeping the total demand constant for a network and the spatial distribution of the demand within a range in the skeletonized networks, how the energy consumption at the pump station, energy loss in the pipe, and the energy storage in the tank vary with the size of the skeletonized networks are investigated in this study. Energy balance model has been set up for each skeletonized model to observe the impact on energy flow for a series of models. Since the number of pipes and nodes can impact hydraulics, which eventually impact the energy flow, the paper considers two types of networks: branch and loop water distribution systems. The study has been applied to two hypothetical literature networks. Due to skeletonization, the flow pattern in the loop system changes more than that in the branch system causing higher percentage change of frictional energy loss in the loop system. The energy consumption or loss per unit demand per node in the skeletonized networks is found almost linear for the branch system. However, this parameter changes non-linearly in the skeletonized networks for the loop system.