5 Water Supply Challenges and Achievements in Constanta County
189
37 m, which is specific for this village. Furthermore, there are essential differences in
elevation, albeit the consumers are in proximity. The actual water demand is 15.26 l/s.
The new-proposed pumping station that will supply the villages Dulcesti, Peceneaga, and Mosneni, according to the regulations regarding water supply systems
(NP133 2013) will be part of a water facility placed in the South-East of Dulcesti
village. Aiming to achieve an optimum energy efficient operation of the pump group
that supplies Dulcesti and, consequently, an affordable water price, we’ve developed
a study of the hydraulic parameters and flow control opportunities, in different operation alternatives. The analyses were conducted with the help of EPANET software,
taking into account various operation possibilities.
In the proposed configuration, water is pumped from the wells into an open reservoir mounted at the elevation of 8.9 m, and then it is pumped into the network by
two identical pumps.
The highest junction, n54 in Fig. 5.7, is in the North-Western part of the village,
at an elevation of 43.11 m. On the other hand, the lowest node is n29, at an elevation
of only 9 m. In the Southern branch of the network, there are differences up to 17 m
between the elevations of nodes n120 and n123, according to the notation in Fig. 5.7.
It has to be mentioned that in EPANET, a system is a collection of interconnected
links and junctions. A reservoir or a tank are junctions, while a pipeline or a pump
are defined as links. All the water demand is concentrated in junctions.
The two identical pumps considered in the proposed solution deliver a flow rate of
7.61 l/s at a total pumping head of 43 m. The study involved two different alternatives
constant and variable speed pumps, to get the best variant for the network operation
and to compare the results regarding efficiency to the existing network.
The simulation was also carried out for the existing network, with its water losses,
that means for a couple of pumps that deliver 28.11 l/s of water, at a total head of
44.5 m, which is considered the reference case for the specific energy consumption.
The standard water demand for the rural area [17] was introduced in the demand
pattern and in the pumps operation timetable, which is a control command in
EPANET.
All the information on pressure and velocity fields, along with results regarding the
specific energy consumption, obtained by simulation, made possible a comparative
investigation of the technical parameters for each alternative.
As it was to be expected, we obtained a pressure difference between the SouthEastern and the North-Western part of the village. In all the studied cases, a minimal
pressure of at least 7 mwc is provided at the furthermost hydrant. For example, in the
node 54, the pressure is 9.26 mwc at the maximal demand value. Pressure increases
in a few nodes up to the maximal allowed value of 60 mwc, for the case when constant
speed pumps are used, but only in the night time, when the demand is low [5].
The velocity field shows values comprised between 0.3 and 0.8 m/s, in the central
pipelines, while in the external ones, where the diameter is large enough for future
expansion of the network, the velocity might decrease under 0.3 m/s [5].
The results regarding the energy efficiency are given in the Table 5.4. The specific
energy consumption coefficient, e, was calculated as a time-weighted average during
24 h.
189
37 m, which is specific for this village. Furthermore, there are essential differences in
elevation, albeit the consumers are in proximity. The actual water demand is 15.26 l/s.
The new-proposed pumping station that will supply the villages Dulcesti, Peceneaga, and Mosneni, according to the regulations regarding water supply systems
(NP133 2013) will be part of a water facility placed in the South-East of Dulcesti
village. Aiming to achieve an optimum energy efficient operation of the pump group
that supplies Dulcesti and, consequently, an affordable water price, we’ve developed
a study of the hydraulic parameters and flow control opportunities, in different operation alternatives. The analyses were conducted with the help of EPANET software,
taking into account various operation possibilities.
In the proposed configuration, water is pumped from the wells into an open reservoir mounted at the elevation of 8.9 m, and then it is pumped into the network by
two identical pumps.
The highest junction, n54 in Fig. 5.7, is in the North-Western part of the village,
at an elevation of 43.11 m. On the other hand, the lowest node is n29, at an elevation
of only 9 m. In the Southern branch of the network, there are differences up to 17 m
between the elevations of nodes n120 and n123, according to the notation in Fig. 5.7.
It has to be mentioned that in EPANET, a system is a collection of interconnected
links and junctions. A reservoir or a tank are junctions, while a pipeline or a pump
are defined as links. All the water demand is concentrated in junctions.
The two identical pumps considered in the proposed solution deliver a flow rate of
7.61 l/s at a total pumping head of 43 m. The study involved two different alternatives
constant and variable speed pumps, to get the best variant for the network operation
and to compare the results regarding efficiency to the existing network.
The simulation was also carried out for the existing network, with its water losses,
that means for a couple of pumps that deliver 28.11 l/s of water, at a total head of
44.5 m, which is considered the reference case for the specific energy consumption.
The standard water demand for the rural area [17] was introduced in the demand
pattern and in the pumps operation timetable, which is a control command in
EPANET.
All the information on pressure and velocity fields, along with results regarding the
specific energy consumption, obtained by simulation, made possible a comparative
investigation of the technical parameters for each alternative.
As it was to be expected, we obtained a pressure difference between the SouthEastern and the North-Western part of the village. In all the studied cases, a minimal
pressure of at least 7 mwc is provided at the furthermost hydrant. For example, in the
node 54, the pressure is 9.26 mwc at the maximal demand value. Pressure increases
in a few nodes up to the maximal allowed value of 60 mwc, for the case when constant
speed pumps are used, but only in the night time, when the demand is low [5].
The velocity field shows values comprised between 0.3 and 0.8 m/s, in the central
pipelines, while in the external ones, where the diameter is large enough for future
expansion of the network, the velocity might decrease under 0.3 m/s [5].
The results regarding the energy efficiency are given in the Table 5.4. The specific
energy consumption coefficient, e, was calculated as a time-weighted average during
24 h.