Environmental Engineering Reference
In-Depth Information
CHAPTER 3
Emitter Based Algorithm
for Pressure-Driven Demand Calculations
of Water Distribution Networks 1
Pressure-driven demand (PDD) models have become essential tools for hydraulic analyses of
water distribution networks under stress conditions. They are commonly based on the concept
of emitter coefficients initially developed within EPANET software of US EPA (Rossman,
2000). Thanks to substantially improved computational speed in the past decade, fairly large
networks can be processed by PDD models, nowadays. Nevertheless, the PDD models are
still unable to simulate some specific situations appearing in reality. The research presented in
this chapter assesses the PDD algorithm for calculations of networks laid in topography with
extreme altitude range. The negative emitter demands resulting from high altitudes are taken
as an indicator of total demand loss and are eliminated after removing the emitter and setting
the node demand to zero. In addition, a situation is analysed where the loss of demand can
also be dependent from altitude range preventing conveyance through non-demand nodes of
extremely high elevation, which are also generating negative pressures. The approach has
been demonstrated on a few simple scenarios. The results point the deficiencies of neglecting
high elevated nodes without the demand and the introduction of lower PDD threshold limit
for (temporary) disconnection of the pipes connected to the negative-pressure nodes.
 
 
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