Development of energy performance
indicators for drinking water pumping
systems
BOUACH AHCENE(1), BENMAMAR SAADIA(2)*
(1);BOUACH
Ahcene
(corresponding
author),
Université
de
Blida
1;E-mail :
bouach.ahcene@gmail.com
(2):BENMAMAR Saadia, Research Laboratory of Water Sciences, National Polytechnic School of
Algiers, 10 Avenue Hassen Badi BP 182 El Harrach 16200 Alger Algérie.
Abstract:
The effective management of drinking water pumping stations is a very complicated task,
where it requires in-depth knowledge and data of the system. To help the managers of these
systems, a list of energy performance indicators has been developed to evaluate, compare
and diagnose pumping stations. These indicators constitute a decision support tool for water
services and allow a global and detailed evaluation of pumping stations in terms of sizing
and operation, and in particular via the tree representation that facilitates the treatment of
malfunctions and the detection of system anomalies.
Key words: WATER SUPPLY, PUMPING STATIONS, PERFORMANCE INDICATORS. ENERGY, SYSTEMS MANAGEMENT.
1 Introduction
Energy assessment is considered an essential step in any effective management of a pumping station.
Indeed, an objective assessment would make it possible to detect the source of the malfunction, if
any, as it would constitute a decision support tool for water service managers.
To assess this energy consumption we can use performance indicators. The idea of using
performance indicators in the hydraulic field in general is relatively old. Indeed, among the first
researchers who are interested in this, we have (Brady et al. 1979) they proposed performance
indicators to evaluate and compare wastewater collection systems. In 1987, Scartezzini et al.
published an article in which they have showed the influence of inhabitants on solar water
installations. The study was carried out using thermal performance indicators.
In the report presented by (Radosevich, 1988) he has studied for three years some performance
indicators such as capacity factor, system efficiency and availability to assess the operational capacity
of a solar thermal station. The use of indicators has allowed the author to observe an improvement
in the system performance. In the study presented by (Sharirli, 1989) he has used performance
indicators to monitor the unavailability of an emergency feedwater system of a nuclear power plant.
These indicators he also called them trend indicators.
From the 90s, research work on performance indicators experienced a qualitative leap with
interesting publications such as the article published by Bos in 1997 in which he summarized about
40 performance indicators used in the context of an irrigation performance research program. These
indicators group together several aspects such as: water distribution, sustainability, efficient water
use, maintenance, environment, and socio-economic aspect. In the same year, (Roerink et al. 1997)
have developed two new performance indicators for irrigation systems: relative evapotranspiration
and water efficiency. These performance indicators are based on the estimation of
evapotranspiration by remote sensing. Also, in the paper published by (Ogden 1997), he has outlined
the rights of consumers in terms of price and quality in the context of privatization. In this aspect the
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office of water services in charge of water management has used the performance indicators to
assess the service offered to customers. One year before, (Makadho, 1996), he has presented a
methodology for calculating the performance indicator called the timeliness indicator to help
agricultures manage water use well. In (Kingdom 1998) he has presented the experience gained from
2 benchmark performance studies in the US water industry. Throughout the paper the author
illustrated 2 distinct but complementary components. The first includes a range of quantitative
assessment and comparison. The second focuses on how to improve existing work processes and
compare similar activities.
In 1999, a series of publications have taken place bringing a rich improvement to this research axis,
such as: In (Alegre 1999). The author has defined performance indicators as the measure of
efficiency and effectiveness. It also defined the framework in which the indicators are used as well as
their objective. In (Srinivasan et al. 1999) they have provided improved performance indicators
addressing failures in water supply reservoirs. This improvement concerns in particular the formalism
of resilience. The performance indicators used were incorporated into a mixed integer programming
model. In (Sakthivadivel et al. 1999), they have defined a set of 4 performance indicators allowing
the comparison of irrigation systems spatially and temporally. In (Lundin et al., 1999) they have
studied the temporal variability of a set of performance indicators in order to assess the
sustainability of urban water systems. These indicators are based on the environment, efficiency and
performance of the system. These indicators have shown the sustainability of urban water systems.
In (Hopkinson et al. 1999) they have studied a new set of environmental performance indicators
developed by the water industry. The study has showed that the use of performance indicators
facilitated the task of comparison and benchmark compared to conventional reports at that time.
In 2002, Alegre et al. they presented an overview on IWA performance indicators for water supply
services. (Gumbo, 2004), he has proposed a water demand management program. Then, he has
studied the water supply systems in eight cities in South Africa using selected performance
indicators. The author has showed through this study that the proposed program gave good results
as he has underlined the need for performance indicators in the management of water systems. (Luc
et al. 2006) they have proposed a set of performance indicators to assess irrigation pumping
systems. They have also identified and criticized the methods applied for estimating the pumped
volume while proposing a method that they consider effective to estimate it. In 2008, (Vieira et al.
2008) have considered that work in this direction was general and it was mainly oriented towards the
economic and managerial aspect. As a result, they have proposed 80 performance indicators which
take into account the technical aspect and are specialized in water treatment.
As part of the "WATER-LOSS management" project, (Kanakoudis et al. 2011) have developed a set of
new performance indicators in order to assess water supply in terms of quantity and quality. The
proposed indicators are adapted to the specific conditions in the Mediterranean and to the lack of
data.
In the last decade, other research has been presented. In (Haider et al. 2014), they were particularly
interested in small-scale supply systems by proposing an evaluation model based on grouped
performance indicators.(Carriço et al. 2014) have proposed a methodology based on the hydraulic
energy balance along a water pipe and four performance indicators to assess the energy efficiency of
water supply systems. The calculation of the indicators is based on the hydraulic simulation of the
system. The application of the indicators demonstrated the practicality of the proposed indicators.
(Vilanova, & Balestieri 2015) have proposed three performance indicators allowing the complete
assessment of water supply systems from operational and physical energy efficiency measures.
These indicators are: hydraulic energy recovery indicator; optimized pumping operation indicator;
and supplied hydraulic head indicator. In (Teixeira et al. 2016) they have developed a matrix of
performance indicators allowing the assessment and control of energy consumed, energy price and
CO2 emissions, contributing to the development of water systems. The indicators developed are
based on integral management systems: ISO 50001 for integral energy management, 1S0 9001 for
quality, 1SSO 14001 for systems. The indicators have been classified into 4 groups: environmental,
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technical, social and technical. The application of the indicators improved water management by
34.3%.
In (Mamade, et al. 2017), they have presented a new energy balance system and performance
indicators to assess the energy efficiency of drinking water supply systems. The novelty lies in the
integrated calculation between the energy and water balance making it possible to quantify the
energy inefficiency linked to water losses. The program has been implemented in Portugal and the
results have shown significant energy saving potential to be addressed. In (Renouf et al. 2017), the
authors have proposed quantitative indicators within the framework of what they called the
metabolic characteristics of urban drinking water management. In this study, the authors examined
the generation of certain indicators via the urban water mass balance method. These indicators are:
Indicators of water efficiency, supply internalisation, and hydrological performance.
In (Umapathi et al. 2019), the authors have used performance indicators to investigate a rainwater
harvesting system for unconventional end use. (Shahzad et al. 2019) they have selected a short list of
performance indicators to quickly assess the quality and quantity of water put into supply systems.
For quality, they have used turbidity, PH, and E-coli. For the quantity they have used the flow
provided in the different sectors of the network.
In 2019, (Bouach & Benmamar 2019) as part of their study of energy optimization of pumping
systems supplying drinking water supply networks. The authors have developed a set of performance
indicators to compare, evaluate and diagnose the system under study.
Recently, (Parakath & Neelakantan 2021) studied three performance indicators related to risk in
supply networks, these indicators are: resilience index, network resilience index and total surplus
head index. In the study (Kandi et al. 2021), the authors have made improvements on existing
performance indicators evaluating the design and operation of pumps as a turbine (PAT).
In this study, we have proposed a list of energy performance indicators that allow us to assess the
energy consumption in a global and detailed way of a pumping station. It also enables comparison.
And make the diagnosis by determining the source of the malfunction.
This task is quite delicate because it requires perfect knowledge of the various formulas used in the
sizing of supply and distribution networks and in-depth knowledge of the hydraulic operation of
pumps. Indeed, the problems of overconsumption of energy in pumping stations can be due to: poor
sizing of structures and equipment in the study phase, or poor management of pumps in the
operation phase. For this, we have developed three types of indicators allowing the energy
assessment of the pumping system:
- Overall energy performance indicators;
- Design energy performance indicators;
- Operational energy performance indicators;
The indicators developed can delimit the source of the malfunction using a tree representation of the
indicators. This will help managers choose which method to use to deal with the overconsumption
problem.
2 Method and tools
The energy performance is assessed against a reference value, this is the optimal value. For this, we
have defined an optimal value for each variable as shown in Table 1.
Table 1: reference values of the performance indicators
Variable
optimal value
Optimal pumping volume
Vopt = Vd - Vi + Vmin
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Optimal pressure
Hopt = Hg.opt + rh.opt.Qopt²
Optimal operating pressure
Hf.opt = Hg + rh.Qopt²
Optimal static head
Hg.opt = Hpd + ΔHd.opt + Hw.t – Cst
Optimal hydraulic resistance
rh.opt = (λopt.Lopt) /(16,2.105,π².g.Dopt5)
Optimal diameter
Dopt = 0,03.(Qha/π.vmin)0,5
Optimal length
Lopt = DS
optimal friction loss factor
λopt=2.Log10(4.10-5/3,7.Dopt + 2,51/[(vmin.Dopt/γ).λopt0,5]
optimal minor loss factor
1
optimal energy
Eopt = (ρ.g.Hopt.Vopt)/(36000.ηopt)
Optimal operating energy
Ef.opt = (ρ.g.Hf.opt.Vopt)/(36000.ηopt)
With, Vd: water demand volume ; Vi : Initial volume of water in the tank; Vmin :Minimum admissible
volume; Hg.opt : optimal static head; rh.opt. : Optimal hydraulic resistance; Hg : static head; Qopt :
Optimal pumping rate; rh : hydraulic resistance ; Hpd : Head of the unfavorable point of the
distribution network; ΔHd.opt : Optimal distribution head losses; Hw.t : water tower head; Cst : suction
tank coast; Qha: Average hourly consumption; DS: Direct distribution distance; γ : water kinematic
viscosity; ρ : water density; g: Acceleration of gravity; ηopt : Optimal pumping efficiency.
2.1 List of performance indicators
The performance indicators developed allow:
- Overall and detailed design assessment
- Overall and detailed operational assessment;
- Overall assessment of the pumping system.
2.1.1
Pumping system energy design indicators
2.1.1.1 Detailed design assessment
The energy consumed by a pumping system depends mainly on the design parameters which are
decisive in the energy consumption. These parameters are:
- Geometric height of the pumping system (static head);
- Parameters of pressure losses (Diameter, length, viscosity force, and singularities).
The various design parameters must have optimal values in order to reduce the energy required for
pumping water. To assess a possible energy malfunction due to an incorrectly dimensioned
parameter, we have developed indicators comparing the system design parameters with optimal
values, in order to assess their impact on energy consumption. Table (2) summarizes the list of
indicators for the design part.
Table 2: Design energy performance indicators
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Performance indicator
formula
static head indicator
GHI
Pipe length indicator
SLI
Signification
H .
H
L
L
L
L
DLI
Pipe diameter indicator
SFI
D
D
λ
λ
DFI
λ
λ
DDI
MLI
Minor loss indicator.
Hydraulic
indicator
resistance
HRI
GHR
Static head rate
Pressure loss rate
Evaluation of the length of the discharge
pipe.
D
D
SDI
Friction indicator
Evaluation of the static head of the
pumping system.
Evaluation of the length of the suction
pipe
PLR
αs :Minor loss coefficient;
r
Evaluation of the diameter of the suction
pipe.
Evaluation of the diameter of the
discharge pipe.
Assess load losses due to friction between
particles and the walls of the suction pipe
(rugosity).
Assess load losses due to the viscosity
friction of the particles between them and
the walls of the discharge line (rugosity).
Evaluate the effect of the minor losses
1
α
.
r
Evaluation of the hydraulic resistance of
the supply pipe.
H
H.
Share of the energy consumed by the
static head of the pumping system.
r ·Q
H.
Share of the energy consumed by the loss
of loads from the pumping system.
2.1.1.2 Overall design assessment
The overall design indicator gives a general view of the energy performance of the system without
taking into account operating variables. In fact, it makes it possible to evaluate from an energy point
of view the sizing of the various design parameters (table 3).
Table 3: Overall design indicators
Performance Indicator
formula
Signification
overall design indicator
Design energy loss
OCI
∆E!
E.
E
E.
"E
Evaluation of the design variables of the
pumping system.
Assessment of energy losses caused by
poor sizing of design parameters.
∆E#
Design energy loss rate
The rate of energy lost due to poor sizing
CEL
· 100
E.
relative to optimal operating energy
The analysis of the formula of the energy consumed, allowed us to note that the variable influenced
by the design parameters is the pumping pressure through the static head and the pressure drop
parameters (diameter, length, roughness, and singularities). For this, we have defined the overall
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design indicator as the ratio between the optimal energy and the optimal operating energy (table 3).
By replacing the optimal energy and the optimal operating energy with their expression, we have:
ρgH V
36000η
H
OCI
*1+
ρgH . V
H.
36000η
The relationship (1) shows that the overall design indicator is also the ratio between the optimal
pressure and the optimal operating pressure.
By replacing the optimal pressure with its expression, we have:
H . ,r . Q
*2+
OCI
H.
After manipulating the equation (2), the equation becomes;
H .
H
r .
r ·Q
*3+
OCI
·
,
·
H
H.
r
H.
This gives the overall design indicator based on the different design indicators.
OCI
GHI · GHR , HRI · PLR
*4+
This formula is very important because it will serve us in establishing the tree representation of
indicators later.
2.1.2
1Energy-operating assessment of the pumping system
2.1.2.1 Detailed operating assessment
This group of indicators relates to the assessment of energy consumption, limited to the operating
parameters of the pumps which are the volume of water pumped, the pressure and the pumping
efficiency. The table (4) lists the indicators of how the pumping system works.
Table 4: operating energy performance indicators (Bouach & Benmamr 2019)
Performance indicator
Formula
Signification
V
Volume pumping idicator
Evaluate pumping volume
VI
V
H.
Pumping pressure idicator.
Evaluate pumping head (pressure)
HI
H
η
Pumping efficiency idicator
Evaluate the pumping efficiency
RI
η
1.2.2. Overall assessment of the energy operating system
The overall operational assessment is carried out using the indicators presented in table 5. The
overall operating indicator makes it possible to assess the energy consumed by the set of pumps over
the optimization horizon, taking into account the operating variables (volume, pressure and pumping
efficiency). It is the ratio between the optimum operating energy and the energy consumed by the
pumping system.
Table 5: Overall operating indicators
Performance indicators
Formula
Signification
E.
Overall operating indicator
Evaluation of the operating variables of the
OFI
E
pumping system.
Operating energy loss
∆E
E"E.
Evaluation of energy losses caused by
operating parameters.
∆E
Rate of operating energy
Rate of energy loss from operation in
FEL
· 100
E
losses
relation to energy consumed.
In order to assess the influence of the different operating variables on energy consumption, we have
developed equation (5), replacing the different terms with their expressions.
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H.
.V
η
V
H.
η
*5+
·
·
VI · HI · RI
H. V
V
H
η
η
This gives the overall operating indicator according to the various operating indicators of the
pumping system (very useful in calculating the tree representation).
OFI
2.1.2.2 Overall energy assessment
The overall energy assessment of the pumping system gives a general idea of the energy
consumption of the system. It can determine overconsumption and compare between several
pumping scenarios. The table (6) summarizes all indicators of overall energy performance.
Table 6: Overall Energy Performance Indicators
Indicator type
Formule
Objectif
E
Overall energy indicator
Overall energy assessment of the pumping
OEI
E
system
Overall energy losses
Overall energy loss rate
∆E
E"E
EL
∆E
· 100
E
Overall assessment of design and operating
energy losses
Share of overall energy losses in relation to
the energy consumed by the pumping
system.
The overall energy indicator allows for a general energy assessment of the pumping system, taking
into account both design and operating variables. It is defined as the ratio between optimal energy
and the energy consumed by the pumping system (Table 6). By developing its formula, we have the
overall energy indicator as a function of the overall design indicator and the overall operating
indicator:
E
E
E.
OEI
·
OCI · OFI
*6+
E
E.
E
Replacing the overall design indicator and the overall operating indicator with their expressions, we
have:
*7+
OEI OCI · OFI *GHI · GHR , HRI · PLR+ · *VI · HI · RI+
2.2 Tree representation of energy performance indicators
The tree representation of the EPIs allows a better understanding of the results. It also facilitates the
process of energy diagnosis of the problem by detecting the source of the energy dysfunction.
This representation is carried out by an algorithm for determining the source of the energy
dysfunction (Figure 1).
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Figure 1: Diagnostic algorithm via tree representation.
Knowing that all the indicators have a unit weighting with the exception of the hydraulic
h
resistance
indicator HRI and the static head indicator GHI which are weighted
ted by the pressure loss rate PLR and
the static head rate GHR successively. Figure (2)
(2 shows thee tree representation of the EPI’s.
EPI
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Figure 2: Tree
ree representation of energy performance indicators
3 Presentation of the study area
To validate the indicators developed, we applied it to the Rassauta pumping station. This pumping
station is composed of three horizontal volute centrifugal pumps in process construction, KSB brand
and ETANORM RG 250-400
400 type, each pump is driven by a SIEMENS brand electric motor, the pumps
suck water from two suction tanks (2x5000 m3). Whose water volume is managed by altimetric
valves. The pumping unit is installed 3 meters below the suction plane, which allows the pumps to
operate under load thus reducing the problems associated with priming and pump cavitation (Figure
3).
Figure 3: Rassauta pumping station
The suction is done via a pipe with a diameter of 900 mm and a length of 105 m. The water is
pumped to the water tower whose floor elevation is 57 m. The diameter of the discharge pipe is 700
mm. This pipe is equipped with an anti-ram
anti
just after the discharge
rge collector, and a flowmeter
connected to a transmission system allowing the data of the pumping flow in real time. For pressure
reading, the system is equipped with a pressure gauge at the outlet of each pump, the water tower is
also equipped with an overflow
erflow and drain line with a diameter of 1000 mm, and a distribution line
with a diameter of 700 mm (Figure 3).
The pumps operate in the mode commonly called (2 + 1), i.e. two pumps operate in cascade and one
standby pump.
The two running pumps are managed
managed by an automatic control system based on the water level in the
water tower. Indeed, when the water level reaches the maximum threshold of 7.3m, one pump
stops, and if the water level drops below the minimum level of 5.4m one pump starts.
According to thiss principle of regulation it is possible that both pumps are stopped when only one
pump is running and the water level exceeds the max level. The automatic management system
consists of alternating the pumps at each start to ensure an equal working time for
fo the three pumps.
The distribution network of Rassauta has a total pipeline line of 82 831 m divided
divided into 8 distribution
sectors. The unfavorable point of the distribution network is at the level of the SS4 distribution sector
of the locality "Bateau Cassé",
sé", whose coast of the natural terrain is 10 m.
The diameter of the main pipe is 150 mm, which causes very high pressure drop during periods of
high consumption during the day.
The water tower of El Hamiz has a volume of 500 m3 characterized by a floor elevation
el
of 38 m and
an overflow elevation of 42 m. This water tower serves the southern part of the city of El Hamiz
whose distribution network includes about 18,408 m of pipes divided into three distribution sectors:
Orange trees, Hamiz 2, and Haouch Batata.
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The hydraulic calculation of the pressure losses showed that the unfavorable point for the supply
system is the el Hamiz
miz water tower.
tower
The distribution network is characterized by an average daily consumption of about 24878 m3/d. The
analysis of the modulation curve (Figure 4)
4) showed that daily consumption passes practically through
three ranges.
The first range begins from 9 to 15 h with a coefficient of hourly point of about 1.2, this period
corresponds to the high consumption of water because of the
the different daily activities of the users:
showers, dishes ... etc. The second range begins from 16 to 22 H characterized by a point coefficient
equal to 1.1, corresponds to the activities relating to dinner and showers, and the third range it
concerns thee night consumption of 23 to 8 hours whose point coefficient is of the order of 0.7
corresponds practically to leaks in the network.
Figure 4:
4 Modulation curve of the water demand
4 Analysis and interpretation of results
The energy diagnosis is done in steps:
steps
- In the first step,, a general assessment of energy consumption is guaranteed by the overall energy
indicator OEI.
- In the second step, the OCI overall design indicator and the OFII overall operating indicator gives a
general energy assessment of the design and operating parameters.
- In the third step, for the design part, the static head and the hydraulic resistance indicators
indicator make it
possible to evaluate the height of the water tower and the other design parameters separately
(diameter, length, ... etc). While for the operation part, the volume VI, pressure HI and RI pumping
efficiency indicators estimate the energy performance of each of these operating parameters.
- In the fourth and final step, to deepen the analysis of energy consumption. The
T indicators of pipe
diameter SDI and DDI (suction and discharge), pipe length SLI
S and DLI (suction and discharge),
frictions SFI and DFI (suction and discharge) and minor losses MLI allow to present an evaluation of
each parameter of the hydraulic resistance
resist
of the pumping system.
4.1 Overall energy assessment
The overall indicators (table 7)) showed the ineffectiveness of the pumping schedule with OEI=0.41
OEI
very far from 1. And 58.94% energy losses. This is a huge loss for the proper functioning of the
system.
4.2 Energy evaluation of design parameters
The design energy performance indicators show that the sizing of the pumping system is good, as
shown by the overallll design indicator of 0.77 (OCI
(OC = 0.77) causing
ing an energy loss of 4,124.58 KWh
which represents 23.45% of the optimal energy (CEL
(
= 23.45%).
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The Static head rate (GHR = 96.90%) shows that the static head represents the most determining
design parameter of energy consumption. This static head is evaluated using the static head indicator
(GHI) which equals 0.79 which means that the dimensioning of the height of the tank is correct.
The design parameters relating to pressure losses are evaluated via the hydraulic resistance indicator
(HRI = 0.01), which shows that in general the parameters relating to pressure losses have been very
incorrectly sized. However, this very low indicator has lost its influence on the overall design
indicator (OCI) due to the fact that the pressure loss rate is very low (PLR = 3.10%), because the PLR is
the weighting coefficient of the HRI for the calculation of the overall design indicator (OCI).
The poor performance of the hydraulic resistance parameters is explained by: the high minor losses
(MLI= 0.12), the long discharge length (DLI= 0.33), and the small discharge diameter (DDI = 0.29) . The
length of the suction line is also important with an SLI = 0.52. The only exception is the diameter of
the suction line which has an excellent indicator (SDI = 1.03).
4.3 Energy evaluation of operating variables
Energy consumption depends on three operating variables (volume, pressure and pumping
efficiency) which are both interdependent and sometimes contradictory. Optimal operation from an
energy point of view requires that the three variables have optimal values, only it is practically rare
to realize such an ideal situation, because often when one wants to operate the pumps at an optimal
efficiency for example this influences negatively the other two variables. The solution to this paradox
is to find a compromise between the three operating variables. As shown by the overall operating
indicator (Table 7).
Although the type of pumping used by water utilities uses a flow regulation method, their energy
performance is poor with an overall operating indicator (OFI) equal to 0.54.
This low operating indicator is influenced by the poor performance of the pumping volume variable
whose indicator (VI) is equal to 0.66, which explains why the schedule creates a significant energy
loss because of this excess water that far exceeds the demand.
This malfunction could be explained by either:
- The level probes in the water tower are poorly adjusted or defective,
- Presence of an internal leak in the water tower.
- Voluntary management to have a maximum water level to increase distribution pressure.
The high pumping volume and the variation of the static head created by the variation of the water
level in the suction tank modify the characteristic curve of the pipe, which displaces the operating
point of the pumping system, thus creating Additional energy losses as confirmed by the pump
pressure indicator HI = 0.88.
Table 7: Energy performance indicators
assessment
Overall
Overall design
Static head
Design
hydraulic resistance
Indicator
OEI
EL [%]
ΔE [KWh]
OCI
ΔEC [kwh]
CEL [%]
GHI
GHR [%]
HRI
PLR [%]
SLI
DLI
SDI
Value
0,41
58,94
19 330,98
0.77
4124.58
23.45
0.79
96.90
0,01
3,1
0,52
0,33
1,03
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Operating
DDI
SFI
DFI
MLI
0,29
0,98
0,97
0,12
OFI
0,54
OEL [KWh]
ROL [%]
VI
HI
RI
15 206,40
46,36
0,66
0,88
0,93
4.4 Tree representation
The tree representation allows a quick and accurate energy diagnosis of the operation of the station:
Indeed, Figure 5 shows a very significant
signifi
energy overconsumption (OEI = 0.41 very low) caused
mainly by the poor pumping schedule, and precisely the pumping volume which far exceeds the
demand (VI = 0.66).
For the design parameters, the energy dysfunction creates by the high singularity, the low discharge
discharg
diameter, and the large length were attenuated by the low associated weighting (PLR
(
= 0.03).
The final finding regarding the diagnosis via the EPI’s clearly indicates a problem of adjustment of the
volume of water. What requires repair of the flow control system (level probes), and the resizing of
certain equipment, which are: the pumps, diameter of the suction line, the diameter of the discharge
pipe and the singularities (valves
valves, elbows, flow meters, ... etc).
Figure 5: Tree representation of the IPEs of the pumping schedule
5 Conclusion
Energy performance indicators are an effective tool in the energy evaluation of the pumping system;
they greatly facilitate this task, and allow system managers to understand the energy situation which
allows them to make adequate decisions to optimize energy consumption.
In this work, we have developed a list of energy performance indicators, which not only has a global
energy assessment, but it offers a detailed assessment to conduct an
an energy diagnosis of each
system parameter, and make credible comparisons between the different pumping scenarios
possible.
The tree representation of the energy performance indicators is a simple and precise method
allowing a quick energy diagnosis of the
the pumping system. The method relies on a panel of EPIs to
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evaluate performance, and on the calculation of the malfunction path to detect the source of energy
overconsumption.
The use of EPI’s energy performance indicators has greatly facilitated the system's energy
assessment and comparison task. They showed the poor performance of the pumping schedule
studied with OEI = 0.41 and EL = 58.94%.
IPEs also made it possible to make an effective diagnosis of the pumping system, detecting poorly
dimensioned parameters in the design or operation phase. Indeed, the IPE’s have shown that the
parameters of the hydraulic resistance have been very poorly dimensioned (HRI = 0.01), this is due to
high singularities MLI = 0.12, and at the low discharge diameter DDI = 0.29 and at the discharge
length DLI = 0.33.
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