Simulation of Water Distribution Networks The Use of EPANET

Water Supply Simulation of Water Distribution Networks The Use of EPANET

Mohammad N. Almasri 1

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Introduction This p presentation focuses on two issues: ƒ The simulation of water distribution networks (WDNs) using EPANET ƒ The optimal design of water distribution networks

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Definitions ƒ A WDN is comprised of a number of links connected together to form loops or branches ƒ These h links l k contain pumps, fittings, f valves, l etc.. ƒ Links: A link is a segment of the network that has a constant flow and no branches. Each link may contain one or more pipes (with ( h different d ff diameters) connected in series ƒ Pipes: A pipe is a segment of a link that has a constant flow, fl constant diameter, di and d no branches 3

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Pipes and Links

A pipe

D1

L

D3

D2

D1

L3

L2

L1

A link

L 4

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Definitions ƒ Nodes: They are the end points of the pipe sections where h two or more links l k are joined. d Water can enter or leave the network at these nodes ƒ LLoops: The Th loop l is i a closed l d circuit i i consists i off a series of links in which the demand nodes are supplied from more than one pipe ƒ Th The path: h It I represents the h way or the h route through which the demand nodes are reached from the source nodes 5

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Example of a Water Distribution Network

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Main Principles of Network Analysis Continuity: y The algebraic g sum of the flow rates in the pipes meeting at a node together with any external flows is zero D

Q1 + Q2 = Q3 + D

Q3 Q1

D = Q1 + Q2 - Q3

Q2

A demand node The node is connected to three supplying pipes 7

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Main Principles of Network Analysis Energy gy conservation: For all p paths around closed loops and between fixed grade nodes, the accumulated energy gy loss including g minor losses minus any energy gain or heads generated by pumps p p must be zero

+

hf1

hf3

hf2 A part of a looped network Closed loop Given total headloss for each link (pipe) as hf

Assume counterclockwise to be positive

hf4 8

-hf hf1 – hf4 + hf3 + hf2 = 0

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Branched WDNs

Q2

Q4

Q5

Q3

[2]

[3]

3

[1]

1

2

5 [4] 4 Q6

Q7 7

9

[6]

[5]

ƒ In branched WDNs, there is onlyy one p path ((route)) from the source node to each node ƒ How can we compute the fl flow in i each h link? li k?

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Branched WDNs

20 30 40

50

[[3]]

[2]

[1]

1

What is the flow in each link?

2

3

5 [4] 4 60

70 7

10

[6]

[5] 6

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Looped WDNs ƒ More than one path to each node ƒ In looped network, how can we compute the flow in each link?

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Main Principles of Network Analysis

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

Link

Head Loss (m)

1

6.753

2

13 238 13.238

3

4.504

4

18 728 18.728

5

3.737

6

4.998

7

9.994

8

9.992

An-Najah National University

Energy Loss in Pipelines – Hazen Williams Formula 1.852

⎛ Q ⎞ h f = 162.5⎜⎜ ⎟ C ⎝ HW ⎠

D

− 4.87

L

hf: head loss (m); L: pipe length (m) D: pipe diameter (in) Q: is flowrate in the pipe (m3/h) CHW: Hazen Williams coefficient (-)

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

ƒ Cast Iron: ƒ New: 130 ƒ 5 year old: 120 ƒ 10 year old: 110

ƒ Plastic: 150

An-Najah National University

What is EPANET? ƒ EPANET is a program for analyzing the hydraulic and water t quality lit behavior b h i off WDNs WDN ƒ D Developed l d by b the th US Environmental E i t l Protection P t ti Agency ƒ It is a public domain software that may be freely copied and distributed ƒ A complete Users Manual as well as full source code and other updates can be downloaded from: www.epa.gov/ORD/NRMRL/wswrd/epanet.html p g / / / / p 14

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

What Does EPANET Do? ƒ Analyzing WDNs. This means mainly the following: ƒ Determination of the flow in each link ƒ Determination of p pressure head at each node

ƒ Additional outcome includes the simulation of chlorine concentration in each link and at each node

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Elements ƒ ƒ ƒ ƒ ƒ ƒ

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Source reservoir p Pumps Pipes Nodes Tanks Valves

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

EPANET Elements – Reservoirs ƒ Reservoirs are nodes that represent an external source or sink of water to the network. They are used to model lakes, rivers, and groundwater aquifers. Reservoirs can also serve as water quality source points ƒ The primary input properties for a reservoir are its hydraulic head and initial water quality ƒ Because a reservoir is a boundary point to a network, its head and water quality cannot be affected by what happens within the network. Therefore it has no computed output properties. However its head can be made to vary with time by assigning a time pattern to it 17

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

EPANET Elements – Tanks ƒ Tanks are nodes with storage capacity, where the volume of stored water can vary with time during a simulation ƒ The primary input properties for tanks are: ƒ Bottom elevation ƒ Diameter (or shape if non-cylindrical) ƒ Initial, I iti l minimum i i and d maximum i water t levels l l ƒ Initial water quality ƒ The principal computed outputs are: ƒ Total head (water surface elevation) ƒ water quality ƒ T Tanks k are required i d to t operate t within ithi their th i minimum i i and d maximum levels 18

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

EPANET Elements – Pipes ƒ Pipes convey water from one point in the network to another ƒ EPANET assumes that all pipes are full at all times ƒ The principal hydraulic input parameters for pipes are: Diameter, Length, Roughness coefficient, and Initial status (open, closed, or contains a check valve) ƒ The water quality inputs for pipes consist of: ƒ Bulk reaction coefficient ƒ Wall reaction coefficient 19

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

EPANET Elements – Pipes ƒ Computed outputs for pipes include: Flow rate, V l it Headloss, Velocity, H dl Friction F i ti factor, f t Reaction R ti rate, t and Water quality ƒ The hydraulic head lost by water flowing in a pipe d to friction due f with h the h pipe walls ll can be b computed d using three different formulas: Hazen-Williams Fo m la Darcy-Weisbach Formula, Da c Weisbach Fo Formula, m la and ChezyChe Manning Formula ƒ Minor losses caused by bends and fittings can also b accounted be t d for f b by assigning i i the th pipe i a minor i loss l coefficient 20

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

EPANET Elements – Pumps ƒ The principal input parameter for a pump is its pump curve ƒ Pumps can be turned on and off at preset times ƒ Variable speed pumps can be considered ƒ EPANET can also compute p the energy gy consumption and cost of a pump

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

EPANET Elements – Valves ƒ Valves are used to control the pressure or flow at a specific point in the network ƒ The main different types yp of valves considered in EPANET include: ƒ PRV (Pressure Reducing Valve): Used to limit pressure ƒ PSV (Pressure Sustaining Valve): To maintain pressure at a certain value ƒ PBV (Pressure Breaker Valve): Forces a specified pressure loss across the valve ƒ FCV (Flow Control Valve): Used to control flow ƒ GPV (General Purpose Valve): Can be used to represent a link where the flow – headloss relationship p is supplied pp byy the user 22

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Network Layout

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

Time Pattern of Demands ƒ Y You can address dd the variability in demands through multipliers of the “Base Base Demand” Demand at each node ƒ This is called in EPANET Time Pattern

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

General Results of EPANET Nodes

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

General Results of EPANET Nodes

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

General Results of EPANET Pipes

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

General Results of EPANET Pipes

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

General Results of EPANET Time series

ƒ Note the negative and positive values of flow ƒ What does this indicate? 29

Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

General Results of EPANET Time series

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University

General Results of EPANET Time series (Pump)

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Optimal Design of Water Distribution Networks – Mohammad N. Almasri, PhD

An-Najah National University