This session is approved for 0.2 IACET or 1.5 PDH. Many states accept this for Professional Continuing Education.

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Alexandrina Sparks
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Important! This session is approved for 0.2 IACET or 1.5 PDH.

To qualify for credit you must: Be sure your badge was scanned when you entered the workshop Stay for the

the epocto proctor as you leave e If you are registered in Florida, New York, or North Carolina, you must also

1 Important! This session is approved for 0.2 IACET or 1.5 PDH. Many states accept this for Professional Continuing Education. To qualify for credit you must: Be sure your badge was scanned when you entered the workshop Stay for the entire session Participate in Question and Answer sessions Fill out the Evaluation auato Form and hand it to the epocto proctor as you leave e 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. TITLE GOES HERE TITLE GOES HERE TITLE GOES HERE TITLE GOES HERE TITLE GOES HERE 1

2 Review of Practices in the District i t Cooling Systems and Pumping Schemes to Manage the Impact on Energy Burj Khalifa Case Study Ahmed Abdul Ganhi Chairman Allied Consultants Cairo, Egypt 2 Learning Objectives 1. Understand distribution systems reliability 2. Determine distribution system energyrunningrunning cost 3. Understand new Middle East techniques in District cooling 3 2

3 United Arab Emirates 4 Dubai 5 3

4 Burj Khalifa 6 Burj Khalifa 7 4

5 Burj Khalifa 8 Burj Khalifa 9 5

6 2012 GEC Ghani Workshop 3/23/2012 Master Plan DCP 1 ASHRAE check Figure 215 Sq.ft/TR Connected Load 45,700 TR Diversity Factor 94 % Plant load DCP 1 DCP 4 DCP 4 43,000 TR ASHRAE check Figure DCP 3 ASHRAE check Figure 80,700 TR Diversity Factor 74 % Plant load 59,500 TR Diversity Factor 67 % 40,000 TR DCP 2 g ASHRAE check Figure 60,000 TR DCP Sq.ft/TR Connected Load Plant load 215 Sq.ft/TR Connected Load DCP Sq.ft/TR Connected load 51,300 TR Diversity Factor 68 % Plant load 35,000 TR DCP 2 10 Master Plan DCP 1 DCP 3 DCP 4 DCP

7 Interface with Building Direct Connection Indirect Connection 12 Direct Connection Advantages More economical no HE (~ 100 $/T exchanger + accessories). No water treatment at user side. Reduced ETS space (xxxxxxx Sq. ft /TR). Increased ΔT thus reduced distribution system capital cost. Rd Reduced dequipment maintenance and potential shutdowns for HE cleaning. Disadvantages Building design pressure should be same as the DCS 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. Plant & network design pressure might be affected by end user. 13 7

8 Direct Connection Decision taken 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 14 Pumping Scheme Primary Secondary 15 8

9 Pumping Scheme Primary Distributed Secondary 16 Case Study Primary Secondary vs. Primary Distributed Secondary 1) Primary Secondary 17 9

10 Case Study 2) Distributed Secondary 18 Pressure Gradient Diagram 1) Primary-Secondary System Pressure Gradient PRESSURE GRADIENT PRIMARY-SECONDARY SYSTEM MAX PRESSURE: 834PSI SYSTEM HEAD (ft) Supply Line Return Line Point 0 VB-01 Plot - A Plot - B Plot - C Plot - D Plot - E VB-2 STATIONS Plot - F Plot - G Plot - H Plot - J Plot - K K------HEX 19 10

11 Pressure Gradient Diagram 2) Primary-Distributed Secondary Pressure Gradient PRESSURE GRADIENT PRIMARY-DISTRIBUTED SYSTEM MAX PRESSURE: 49.5 PSI SYSTEM HEAD (ft) Supply Line Return Line Pressure at Each Station Point 0 - PP-S VB-01 Plot - A Plot - B Plot - C Plot - D Plot - E STATIONS VB-2 Plot - F Plot - G Plot - H Plot - J Plot - K Observe Pump Head Max System Pressure 20 Energy Curve of Both YEARLY POWER CONSUMPTION PRIMARY-DISTRIBUTED VERSUS PRIMARY SECONDARY POWER CONSUMPTION (KW) P Primary Secondary Distributed Secondary MONTHS 21 11

12 Energy Saving Table System Primary Secondary Primary Distributed Secondary Months (KW) (KW) January February March April May June July August September October November December TOTAL (MW) Advantages of Selected Pumping Scheme No ΔP control valve required. Distributed pumps handle the pressure variations. Chilled water can be obtained from any plant

13 Advantages of Selected Pumping Scheme Any supply temperature could be achieved by direct mixing as return pressure higher than supply 24 DCP Configuration DCP 2 Convention Plant Capacity 35,000 TR DCP 1 Ice Storage Capacity 40,000 TR 25 13

14 DCP 2 What are chillers arrangement configurations? 1) Parallel Arrangement 26 DCP 2 2) In-Series Arrangement Series chillers have better kw/ton. Single path chiller with lower ΔP across evaporator. Both chillers in series have higher primary pump head

15 What Happens if Secondary is not Matching Primary? Fig-1: Series Arrangement 28 What Happens if Secondary is not Matching Primary? Fig-2: Parallel Arrangement 29 15

16 Load Profile has to be Analyzed Loading % in each arrangement should be computed LOADING PERCENTAGE COMPARISON LOA ADING PERCENTAGE HOURS Series Arrangement Parallel Arrangement 30 Load Profile has to be Analyzed Hour by hour energy needs to be computed Fig-1 Inseries Arrangement 31 16

17 Load Profile has to be Analyzed Fig-1 Parallel Arrangement 32 Buffer Tank (TES) May Improve the chiller KW/ton as the chillers will be loaded at all their best efficiency time, but no space 33 17

18 Buffer Tank (TES) Advantages Reduced compressor lift. 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 loadingpercentage include pumping energy in primaryandand condenser circuits. Net results. Shows saving if chiller staging is properly watched. 34 Chiller Arrangement of DCP 2 Series counter flow configuration 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 35 18

Cooling Tower Types Counter Flow Cross Flow Induced draft counter-flow tower Induced draft cross-flow tower 36 Advantages of Counter Flow Easier to maintain as water basin not

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.

19 Cooling Tower Types Counter Flow Cross Flow Induced draft counter-flow tower Induced draft cross-flow tower 36 Advantages of Counter Flow 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. 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 meanless prone to recirculation effect. When towers are laid side by side, towers still accessible. Less pumping energy as no spray nozzles pressure

20 arge V d Plume 2012 GEC Ghani Workshop 3/23/2012 Orientation with Wind Direction Disch Wind Vw Vp 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 38 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) 39 20

21 For Wet Coolers where: Humidity is expressed in absolute units of moisture content, for example, grains of moisture per pound of air. 40 For Wet Coolers Recirculation impacts design wet bulb temp CFD Modeling Conducted to validate tower performance at prevailing wind speed. Capacity Heat rejection Chiller motor cooling Safety Design wet bulb temp. considering recirculation Pump NPSH NPSH A > NPSH R H s + H a H f H v > NPSH R Found safe Other tools to overcome NPSH issues 41 21

22 For Wet Coolers Sand storm & development construction activity dust Cooling tower dirt removal Sweeper systems Side stream filtration Ozone Issues & concerns of ozone Corrosion of steel parts (chiller marine box) 42 Other Points Considered Network air venting & dirt removal Impact of air on pump p 43 22

23 Other Points Considered Gas venting (oxygen + nitrogen) Source Air dissolved in make up water: used up by the initial corrosion. Air trapped in the system after initial filling: proper air venting Large bore vent to pass air bubble Surface tension breaker 44 Other Points Considered 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

24 Other Points Considered Air vents (1.64 ft/s) Air & dirt separators Water speed versus removal time ascending flow (3.28 ft/s) (2.46 ft/s) (1.64 ft/s) Water speed versus removal time horizontal pipe 46 Other Points Considered Baffle Separator Centrifugal Separator Wire Mesh Separator 47 24

25 Plant Configuration Plant Arch 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 ( Sq.m/T) Pumps require area 0.32 Sq. ft/t (0.03 Sq.m/T) 48 Plant Configuration Basement: Ground: Mezzanine: Roof: Pumps + water tank Height 7 mt Chiller Hall + Electrical + Expansion Height 9 mt Crane Offices + Control Room Isolation from structure via vibration matt. Cooling Tower 49 25

26 DCP 2 Plant Section 50 DCP 2 Photo 51 26

27 District Cooling Plant 1 First large size district plant with Ice storage Capacity TR Foot print 200 x 200 ft (60 x 60 m) Piles completed with no basement Challenges Foot print notadequate for heat rejection equipment (200 x 200 ft) No basement available No space for chillers at ground floor 52 District Cooling Plant 1 Mall design Temp differs from Burj ΔT16 o F ( 8.8 o C) Supply 42 o F(5.5 o C) Temp Challenge due to 5 stages with cascaded ETS 56 o F 37 o F 53 27

28 District Cooling Plant 1 Solution Thermal storage No sufficient land for chilled storage m /Thr Low temp below 39.4 o F so chilled storage not possible due to density change. Ice storage technique m 3 /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 $) 54 District Cooling Plant 1 Condenser pump on 1st floor NPSH A not sufficient Proposed NPSH diffuser CT on roof elevated dby 2 mt 55 28

District Cooling Plant 1 Low Supply Temp Chillers Load achieved through: Low temp

Glycol chillers to produce ice and operate at peak load via glycol heat

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

29 District Cooling Plant 1 Low Supply Temp Chillers Load achieved through: Low temp chillers as base load to operate at 37 o F (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 ). 56 District Cooling Plant 1 Ice Storage Discharging Mode Glycol Chillers Ice Storage Glycol Chillers Chilling Mode Base Load Chillers The Peak Day Load Profile External Melt Ice-On-Coil 57 29

30 Flow Diagram 58 DCP 1 Plant Section 59 30

31 DCP 1 Plant Section Challenges Dirt impact on glycol chiller tube heat transfer. Manualcleaning is required to maintain capacity. Automatic tube cleaning was used with brushes + diverting valve + controller to clean tubes 4 times /Day. 60 DCP 1 Plant Section ATB System Valve Automatically reverses flow for 30 sec every six hours ATB System Control 61 31

32 DCP 1 Plant Section 62 DCP 1 Plant Section 63 32

33 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

Large University Central Chiller Plant Design Considerations

Carrier Engineering Newsletter Volume 5, Issue 3 Large University Central Chiller Plant Design Considerations Large campus chilled water plants have unique constraints and need careful evaluation for successful