2012 GEC PPT GANHI REVISED 3 13 12 · Impact on Energy – Burj Khalifa Case Study Ahmed Abdul Ganhi Chairman 2 Allied Consultants Cairo, Egypt Learning Objectives 1

2012 GEC Ghani Workshop 3/23/2012

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R i f P ti i th Di t i t C liReview of Practices in the District Cooling Systems and Pumping Schemes to Manage the Impact on Energy – Burj Khalifa Case Study

Ahmed Abdul Ganhi

Chairman

2

Chairman

Allied Consultants

Cairo, Egypt

Learning Objectives

1. Understand distribution systems reliability

2. Determine distribution system energy running2. Determine distribution system energy running cost

3. Understand new Middle East techniques in District cooling

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United Arab Emirates

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Dubai

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4

Burj Khalifa

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Burj Khalifa

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Burj Khalifa

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Burj Khalifa

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DCP1

DCP4

DCP‐1

ASHRAE check Figure 215 Sq.ft/TR

Connected Load 45,700 TR

Diversity Factor 94 %DCP 4

Master Plan

Plant load 43,000 TR

DCP‐2


DCP‐3



Diversity Factor 74 %

DCP‐4





DCP2

DCP3

g 215 Sq.ft/TR

Connected load 51,300 TR




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DCP1

DCP4

Master Plan

DCP2

DCP3

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Direct Connection Indirect Connection

Interface with Building

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Advantages• More economical no

HE (~ 100 $/T exchanger + accessories).

Disadvantages• Building design pressure

should be same as the DCS which could add cost to the

Direct Connection

accessories).• No water treatment at user

side.• Reduced ETS space

(xxxxxxx Sq. ft /TR).• Increased ΔT thus reduced

distribution system capital cost.R d d i

which could add cost to the end user.

• Cross contamination that could affect both systems.

• Building specific water treatment may not be met as treatment at central plant.l k d• Reduced equipment

maintenance and potential shutdowns for HE cleaning.

• Plant & network design pressure might be affected by end user.

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• Decision taken

• ETS for all users except for Mall (direct connection)

Direct Connection

• ETS for all users except for Mall (direct connection) owned by the Energy Provider.

• Burj indirect due to static impact.

• Pipes‐ Pre insulated with HDPE Jackets‐ Leak detectors

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Primary–Secondary

Pumping Scheme

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Pumping SchemePrimary–Distributed Secondary

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Case StudyPrimary–Secondary vs. Primary‐Distributed Secondary

1) Primary Secondary

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2) Distributed Secondary

Case Study

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1) Primary-Secondary System – Pressure Gradient

PRESSURE GRADIENTPRIMARY-SECONDARY SYSTEM

200.000MAX PRESSURE:

83 4 PSI

Pressure Gradient Diagram

50.000

75.000

100.000

125.000

150.000

175.000

SY

ST

EM

HE

AD

(ft)

Supply Line

Return Line

83.4 PSI

0.000

25.000

Point

0

VB-01

Plot -

A

Plot -

B

Plot -

C

Plot -

D

Plot -

EVB-2

Plot -

F

Plot -

G

Plot -

H

Plot -

J

Plot -

K

K------

HEX

STATIONS

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PRESSURE GRADIENTPRIMARY-DISTRIBUTED SYSTEM

175.000

200.000

2) Primary-Distributed Secondary – Pressure Gradient

Pressure Gradient Diagram

25.000

50.000

75.000

100.000

125.000

150.000

SY

STE

M H

EA

D (ft)

Supply Line

Return Line

Pressure at Each Station

MAX PRESSURE: 49.5 PSI

0.000

Point

0 -

PP-S

VB-01

Plot -

A

Plot -

B

Plot -

C

Plot -

D

Plot -

EVB-2

Plot -

F

Plot -

G

Plot -

H

Plot -

J

Plot -

K

STATIONS

‐ Observe Pump Head ‐Max System Pressure

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YEARLY POWER CONSUMPTIONPRIMARY-DISTRIBUTED VERSUS PRIMARY SECONDARY

800000.00

Energy Curve of Both

200000 00

300000.00

400000.00

500000.00

600000.00

700000.00

PO

WE

R C

ON

SU

MP

TIO

N (

KW

)

Primary Secondary

Distributed Secondary

0.00

100000.00

200000.00

1 2 3 4 5 6 7 8 9 10 11 12

MONTHS

P

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SystemMonths

Primary Secondary (KW)

Primary Distributed Secondary (KW)

January 114830.54 55911.45

February 145975 33 71075 98

Energy Saving Table

February 145975.33 71075.98

March 306453.67 149213.53

April 359681.81 175130.52

May 494584.78 240815.33

June 629377.48 306446.44

July 666851.04 324692.46

August 659807.36 321262.87

September 543639.12 264700.08

October 404525.63 196965.16

November 248761.68 121123.06

December 155666.54 75794.67

TOTAL (MW) 4730.15 2303.13

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Advantages of Selected Pumping Scheme

• No ΔP control valve required. Distributed pumps handle the pressure variations.

• Chilled water can be obtained from any plant.

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Any supply temperature could be achieved by direct mixing as return pressure higher than supply

Advantages of Selected Pumping Scheme

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DCP Configuration

DCP‐2 Convention Plant Capacity 35,000 TR

DCP‐1 Ice Storage Capacity 40,000 TR

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What are chillers arrangement configurations?

1) Parallel Arrangement

DCP ‐ 2

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• Series chillers have better kw/ton

2) In-Series Arrangement

DCP ‐ 2

kw/ton.

• Single path chiller with lower ΔP across evaporator.

• Both chillers in‐series have higher primary pump headhigher primary pump head.

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Fig-1: Series Arrangement

What Happens if Secondary is notMatching Primary?

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Fig-2: Parallel Arrangement

What Happens if Secondary is notMatching Primary?

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LOADING PERCENTAGE COMPARISON

Load Profile has to be AnalyzedLoading % in each arrangement should be computed

40.00

50.00

60.00

70.00

80.00

90.00

100.00

AD

ING

PE

RC

EN

TA

GE

0.00

10.00

20.00

30.00

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300

HOURS

LO

A

Series Arrangement Parallel Arrangement

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Fig-1 Inseries Arrangement

Load Profile has to be AnalyzedHour by hour energy needs to be computed

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Fig-1 Parallel Arrangement

Load Profile has to be Analyzed

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May Improve the chiller KW/ton as the chillers will be loaded at all their best efficiency time, but no space

Buffer Tank (TES)

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Advantages• Reduced compressor lift.

Disadvantages

Buffer Tank (TES)

Disadvantages• Increased chilled water pump head (two in‐series evaporators). • Increased condenser pump head (two in‐series condensers).• Increased bypassed energy through decoupler.

Conclusion• Analyze series/parallel arrangement with load profile and chiller loading percentage include pumping energy in primary andloading percentage include pumping energy in primary and condenser circuits.

• Net results. • Shows saving if chiller staging is properly watched.

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• Series‐counter flow configuration

Chiller Arrangement of DCP‐2

• Number of chillers original design = (2 x 2500) x 7 modules

• Number of chillers used (2 x 1250) x 14 modules

• Increased number of chillers staging

• Reduced wastage of energy through decouple

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Counter Flow Cross Flow

Cooling Tower Types

Induced draft counter-flow tower Induced draft cross-flow tower

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• Easier to maintain as water basin not restricted by wet deck.• Less space needed because of increased efficiency and lack of plenum space required for cross flow towers

Advantages of Counter Flow

plenum space required for cross flow towers.• Longer service life as deck supported from structural supports underneath. No sagging as cross flow.

• Wet deck is encased on all sides with no impact from direct prevailing wind.

• No hot water basin on top of tower, so less and easy maintenance achieved.

• Taller in height that mean less prone to recirculation effect• Taller in height that mean less prone to recirculation effect.• When towers are laid side by side, towers still accessible.• Less pumping energy as no spray nozzles pressure.

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Wind

Vw

Discharge Vd

Plume

Vp

Orientation with Wind Direction

Effect of wind velocity and discharge velocity on plume behavior

Recirculation potential in a forced draft cooling tower

Comparative recirculation potential of round and rectangular towers

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Orientation with Wind Direction

Proper orientation of towers in a prevailing longitudinal wind (requires relative minimal tower size adjustment to compensate for recirculation and interference effects)

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For Wet Coolers

where:Humidity is expressed in absolute units of moisture content for example grains of moisture per pound of aircontent, for example, grains of moisture per pound of air.

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• Recirculation impacts design wet bulb temp• CFDModeling

‐ Conducted to validate tower performance at prevailing wind d

For Wet Coolers

speed.• Capacity

‐ Heat rejection‐ Chiller motor cooling‐ Safety‐Design wet bulb temp. considering recirculation

• Pump NPSH‐ NPSHA > NPSHRNPSHA NPSHR

Hs + Ha ‐ Hf ‐ Hv > NPSHR

‐ Found safe‐ Other tools to overcome NPSH issues

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• Sand storm & development construction activity dust

For Wet Coolers

y‐ Cooling tower dirt removal

• Sweeper systems• Side stream filtration

•Ozonef• Issues & concerns of ozone

• Corrosion of steel parts (chiller marine box)

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• Network air venting & dirt removal

• Impact of air on pump

Other Points Considered

p p p

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Gas venting (oxygen + nitrogen)

• Source


‐ Air dissolved in make up water:

‐ Air trapped in the system after initial filling:

used up by the initial corrosion.

proper air venting

• Large bore vent to pass air bubble Surface tension breaker

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Diffusion: Expansion Tanks


Expansion tank with a bag Expansion tank with a membrane

• Air ingress due to negative pressure: expansion tank pressure should be maintained.

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• Air vents

Ai & di

(1.64 ft/s)


• Air & dirt separators

(3.28 ft/s)

(2.46 ft/s)

Water speed versus removal time – ascending flow

(1.64 ft/s)

Water speed versus removal time – horizontal pipe

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Baffle Separator

Centrifugal Separator

Wire Mesh Separator

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Plant Arch Configuration

Plant Configuration

• Plant foot print 200 x 200 ft (60 x 60 mt)

• Chillers foot print 0.75 Sq. ft/T (0.07 Sq.m/T)

• Heat rejection required area 0.43 Sq.ft/T (0.04 Sq.m/T)

• Electrical work required area 0 54 Sq ft/T (0 05 Sq m/T)• Electrical work required area 0.54 Sq.ft/T (0.05 Sq.m/T)

• Pumps require area 0.32 Sq. ft/T (0.03 Sq.m/T)

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Basement: Pumps + water tankHeight 7 mt

Plant Configuration

Ground: Chiller Hall + Electrical + ExpansionHeight 9 mtCrane

Mezzanine: Offices + Control RoomIsolation from structure via vibration matt.

Roof: Cooling Tower

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DCP‐2 Plant Section

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DCP‐2 Photo

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• First large size district plant with Ice storage

• Capacity 43000 TR

District Cooling Plant‐1

p y

• Foot print 200 x 200 ft (60 x 60 m)

• Piles completed with no basement

• Challenges‐ Foot print not adequate for heat rejection equipmentFoot print not adequate for heat rejection equipment

(200 x 200 ft)‐ No basement available ‐ No space for chillers at ground floor

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• Mall design Temp differs from Burj‐ ΔT 16oF ( 8.8oC)‐ Supply 42oF(5.5oC)


Supply 42 F(5.5 C)

• Temp Challenge due to 5 stages with cascaded ETS

37oF

56oF

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Solution

• Thermal storage ‐ No sufficient land for chilled storage 0 3 ‐ 0 6 m3/Thr


‐ No sufficient land for chilled storage 0.3 ‐ 0.6 m /Thr‐ Low temp below 39.4oF so chilled storage not possibledue to density change.

• Ice storage technique 0.07‐ 0.08 m3/Thr

• Tank on ground and up to 1st floor

• As tank occupied the ground, chillers moved to 1st floor

• Electric platform elevator 40 T on capacity (4.5 M US $)

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• Condenser pump on 1st floor

• NPSH not sufficient


• NPSHA not sufficient

• Proposed NPSH diffuser

f l d b 2• CT on roof elevated by 2 mt

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• Low Supply Temp Chillers


• Load achieved through:‐‐ Low temp chillers as base load to operate at 37oF (20,000 TR ).

‐ Glycol chillers to produce ice and operate at peak load via glycol heat exchangers (15,000

)TR).‐ Heat exchangers between tank water and chilled water (7,000 TR ).

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Ice StorageDischarging Mode


The Peak Day Load Profile

Base Load Chillers

Glycol ChillersChilling Mode

Glycol ChillersIce Storage

External Melt Ice-On-Coil 57


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Flow Diagram

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Challenges• Dirt impact on glycol chiller tube heat transfer Manual cleaning is required


transfer. Manual cleaning is required to maintain capacity.

• Automatic tube cleaning was used with brushes + diverting valve + controller to clean tubes 4 times /Day.

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ATB System Control

ATB System ValveAutomatically reverses flow for 30 sec every six hours

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REMEMBER TO FILL OUT AND TURN IN THE EVALUATION FORM

Reminder: If you are registered in Florida, New York, or North Carolina, you must also sign the sheets in the back at the end of the session. Please print your name, include your registration number, and sign the sheet.

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Documents

2012 GEC PPT GANHI REVISED 3 13 12 · Impact on Energy – Burj Khalifa Case Study Ahmed Abdul Ganhi Chairman 2 Allied Consultants Cairo, Egypt Learning Objectives 1