Supplying potable water in large urban areas through pressurized water networks consumes enormous energy. The bottom-up approach for energy balance supports the detailed energy assessment based on physical pro-cesses of water networks, and thus it is possible to evaluate the energy transformation of each process. However, it is difficult to perform this ap-proach in a real network because it needs a large quantity of data and a cal-ibrated mathematical model to evaluate each process. In this study, we per-form the bottom-up approach for energy balance of Ladkrabang water dis-tribution pumping station, Bangkok, Thailand. The EPANET 2.0 software is used for modeling the water network in the pumping station. The network starts with an inlet pipe of 2,000 mm diameter from a riser of the transmis-sion tunnel system. Water flows in a 52,740 m3 storage tank controlled by 4 influent valve sets. Then, 4 variable speed pumps suck water from the tank and deliver it to the water distribution network via an outlet pipe of 1,800 mm diameter. The energy balance in April 2018 is estimated. The average water discharge is 343,715 m3/day, and the average inlet and outlet energy heads are 5.35 m and 17.5 m above mean sea level, respectively. The total input energy of 24,400 kW.hr/day (100%) is divided into the natural input energy from the riser of 5,000 kW.hr/day (20.5%) and the shaft input ener-gy of 19,400 kW.hr/day (79.5%). The total energy is delivered to the outlet pipe of 17,200 kW.hr/day (70.4%), and thus the total energy loss is 7,200 kW.hr/day (29.6%). The loss is comprised of the friction energy of the inlet pipe of 1,400 kW.hr/day (5.8%), the energy loss due to the throttled influ-ent valves and tank of 300 kW.hr/day (1.2%), the energy loss due to the pump inefficiency of 3,900 kW.hr/day (15.9%), and the friction energy of the outlet pipe of 1,600 kW.hr/day (6.7%). As a result, if the pumping sta-tion is changed into a booster pumping station without a storage tank, it may save the energy roughly 1,700 kW.hr/day (7.0%) from a shorter inlet pipe, no throttled valves and tank, but the change will sacrifice water sup-ply reliability.
Keywords: Energy Balance, Water Distribution Network, Pumping Station, EPANET, Thailand.
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