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Cooling Towers for District Cooling Towers for District Cooling Cooling
Georges Hoeterickx Georges Hoeterickx
Evapco EuropeEvapco Europe
Cooling Towers for District Cooling Cooling Towers for District Cooling Design considerations Design considerations
ApproachApproach : :
Difference between cooling tower water outlet Difference between cooling tower water outlet temp. and design entering wb temp.temp. and design entering wb temp.
Design considerations Design considerations Cooling tower size versus approachCooling tower size versus approach
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1
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3 4 5 6 7 8 9 10 11 12
Co
oli
ng
To
we
r S
ize
Approach ° F
Design considerations Design considerations
Minimum approachMinimum approach
CTI Certification under STD-201CTI Certification under STD-201
Certification is limited to thermal operating Certification is limited to thermal operating conditions….. and a cooling approach of conditions….. and a cooling approach of 2.8°C (5°F) or greater….2.8°C (5°F) or greater….
Cooling Towers forCooling Towers for District Cooling District Cooling
Cooling tower rangeCooling tower range
RangeRange : :
Difference between cooling tower water Difference between cooling tower water
inlet and cooling tower outlet temperature. inlet and cooling tower outlet temperature.
Design considerationsDesign considerations
CoolingCooling tower size versus range tower size versus range
0
0,2
0,4
0,6
0,8
1
1,2
80% 90% 100% 110% 120% 130% 140% 150%
Range
C.T
. S
ize
Cooling Towers for District Cooling Cooling Towers for District Cooling
Design considerations Design considerations
Avoid recirculationAvoid recirculation : :
Bypass of warm discharge air into the cooling Bypass of warm discharge air into the cooling tower air inlet will cause capacity losses. tower air inlet will cause capacity losses.
Design considerations Design considerations
Avoid recirculationAvoid recirculation
Top of cooling tower should be at least level Top of cooling tower should be at least level with enclosure.with enclosure.
Design considerations Design considerations
Avoid recirculationAvoid recirculation
Fan discharge velocity : min. 1200 fpm Fan discharge velocity : min. 1200 fpm (6 m/sec). (6 m/sec).
Downward velocity : max. 600 fpmDownward velocity : max. 600 fpm
(3 m/sec).(3 m/sec).
Design considerations – two side Design considerations – two side air inlet air inlet
Avoid recirculationAvoid recirculation
Limit downward velocity - two side air inlet unitsLimit downward velocity - two side air inlet units
Design considerations – single air Design considerations – single air inlet inlet
Avoid recirculationAvoid recirculation
Limit downward velocity - single air inlet unitsLimit downward velocity - single air inlet units
Cooling Towers for District Cooling Cooling Towers for District Cooling Fan motors Fan motors
High efficiencyHigh efficiency 50° C Rise50° C Rise Space heatersSpace heaters
(avoid condensation) (avoid condensation) VFD compatibleVFD compatible
(insulated end shields)(insulated end shields)
Cooling Towers for District Cooling Cooling Towers for District Cooling Fan MotorsFan Motors
Use of VFD’s for fan motorsUse of VFD’s for fan motors : :
Allow to control air flow through the cooling Allow to control air flow through the cooling towertower
Safe Fan KWSafe Fan KW
Design considerations Design considerations VFD’s for fan motors VFD’s for fan motors
Energy saving ? Energy saving ?
Condenser water temp 1°FCondenser water temp 1°F
Chiller efficiency 3%Chiller efficiency 3%
Cooling tower kW = ~ 5 %Cooling tower kW = ~ 5 %
Chiller kW. Chiller kW.
Design considerations Design considerations VFD’s for fan motorsVFD’s for fan motors
Water consumption : Water consumption : Air flow Water consumption Air flow Water consumption
Plume formation :Plume formation : Air flow Plume formation tendency Air flow Plume formation tendency
Noise control @ night Noise control @ night Fan @ half speed : – 9 dBA fan noiseFan @ half speed : – 9 dBA fan noise
(60% capacity) (60% capacity)
Design considerations Design considerations
VFD’s for fan motorsVFD’s for fan motors
Min. RPM for gear Min. RPM for gear
(motor speed (motor speed ≥≥ 450 RPM) 450 RPM)
Gear with mechanical oil pump for proper Gear with mechanical oil pump for proper lubricationlubrication
Cooling Towers for District Cooling Cooling Towers for District Cooling
Cooling Tower BasinCooling Tower Basin : :
Hold circulating water of the tower. Hold circulating water of the tower.
Design considerations Cooling Tower Design considerations Cooling Tower Basin Basin
Common basinCommon basin
+ Easier basin and cooling tower construction.+ Easier basin and cooling tower construction. + No need for equalizing connection+ No need for equalizing connection
- Maintenance – sump cleaning- Maintenance – sump cleaning
Design considerations Cooling Tower Design considerations Cooling Tower Basin Basin
Individual Basin per Cell Individual Basin per Cell
+ Easier for maintance (water)+ Easier for maintance (water)
- Need equalizing between basins.- Need equalizing between basins.
- More costly construction- More costly construction
Design considerations Water Design considerations Water Outlets Outlets
Design considerations Cooling Tower Design considerations Cooling Tower Bassin Bassin
Sound mats to reduce water noiseSound mats to reduce water noise Noise reduction functionNoise reduction function number of layersnumber of layers distance mats – water in basin !distance mats – water in basin !
Sound mats will obstruct basin access : Sound mats will obstruct basin access : maintenance !maintenance !
Cost distribution main itemsCost distribution main items
Fan
Gear & Motor
Fill
Structure
Louvers
DE
Water Dis.
Fan Stack
Other
Cooling Tower StructureCooling Tower Structure
Typical requirementsTypical requirements: :
Cooling Towers for District CoolingCooling Towers for District CoolingFRP StructureFRP Structure
Reputable manufacturers have their Reputable manufacturers have their components third party tested percomponents third party tested per
ASTM E 84 for strength values and ASTM E 84 for strength values and flamabilityflamability
Ask if these evidences are part of contract Ask if these evidences are part of contract submittals ! submittals !
FRP StructureFRP Structure
Boron Free Advantex glass assuresa longer life of the structure
FRP StructureFRP StructureObtain the specified qualityObtain the specified quality
FRP StructureFRP Structure
UV protectionUV protection
UV degradation and moisture penetration UV degradation and moisture penetration will have influence life time of an FRP will have influence life time of an FRP cooling towercooling tower
The UV rays will cause the decomposition of The UV rays will cause the decomposition of the polymers holding the fibre glass togetherthe polymers holding the fibre glass together
FRP structureFRP structure
UV protectionUV protection
Surface veil material of non woven polyester Surface veil material of non woven polyester fabric to prevent fiber blow outfabric to prevent fiber blow out
Surface veil creates a resin rich surface area Surface veil creates a resin rich surface area to provide enhanced UV protectionto provide enhanced UV protection
One mil thickness of surface veil =One mil thickness of surface veil = 2 – 3 years life time2 – 3 years life time
STRUCTURAL RESIN 55-25%GLASS 45-75%WOVEN ROVEN ANDCONTINUOUS GLASS250 MILS OR MORE
CORROSION BARRIERRESIN 60-70 %GLASS 30-40%MAT OR CLOTH40-60 MILS
EXTERNAL LINERRESIN RICH 80-90%GLASS 10-20% 15-20 MILSSURFACING VEIL TYPE C10-20 MIL THICKNESS
FRP structureFRP structureUV protectionUV protection
FRP structure FRP structure UV protectionUV protection
0
10
20
30
40
50
60
70
80
5 10 15 20 25 30Years
Midde East Climate
European Climate
Useful life of UV projected componentsUseful life of UV projected components
FRP structure FRP structure UV protectionUV protection
How to verify UV protection qualityHow to verify UV protection quality ? ?
Have samples of different weight veil Have samples of different weight veil material for comparison.material for comparison.
Variation in the visibility of the ContiniousVariation in the visibility of the Continious
Filament Mat. Filament Mat.
FRP StructureFRP StructureFire retardancyFire retardancy
Fire resistance and damage control of the Fire resistance and damage control of the
FRP structure. FRP structure.
FRP structure FRP structure Fire retardancyFire retardancy
Design with high quality, heat resistant / fire Design with high quality, heat resistant / fire retardant resin systems, Class 1 typeretardant resin systems, Class 1 type
Specify self extinguishingSpecify self extinguishing
High glass content = minimum burn rateHigh glass content = minimum burn rate
Obtain the required qualityObtain the required qualityFRP structure FRP structure
Major part of the cooling tower cost Major part of the cooling tower cost Most critical item for the cooling tower life Most critical item for the cooling tower life
time !time !
How to obtain the required quality ? How to obtain the required quality ?
Obtain the required qualityObtain the required qualityFRP structureFRP structure
1. Demand cooling tower supplier names the FRP 1. Demand cooling tower supplier names the FRP source and ask delivery certificates from the source and ask delivery certificates from the FRP manufacturer.FRP manufacturer.
2. Reserve the right to inspect before delivery to 2. Reserve the right to inspect before delivery to verify Quality Process Map is complied with. verify Quality Process Map is complied with.
Obtain the required qualityObtain the required qualityFRP structureFRP structure
1. Demand cooling tower supplier names the FRP 1. Demand cooling tower supplier names the FRP source and ask delivery certificates from the source and ask delivery certificates from the FRP manufacturer.FRP manufacturer.
2. Reserve the right to inspect before delivery to 2. Reserve the right to inspect before delivery to verify Quality Process Map is complied with. verify Quality Process Map is complied with.
Obtain the required qualityObtain the required qualityFRP structureFRP structure
1. Demand cooling tower supplier names the FRP 1. Demand cooling tower supplier names the FRP source and ask delivery certificates from the source and ask delivery certificates from the FRP manufacturer.FRP manufacturer.
2. Reserve the right to inspect before delivery to 2. Reserve the right to inspect before delivery to verify Quality Process Map is complied with. verify Quality Process Map is complied with.
Cooling tower fansCooling tower fans
Obtain the best quality Obtain the best quality
FansFans
Fans are selected for a given airflow and Fans are selected for a given airflow and static pressure static pressure
Fan design parameters : Fan design parameters : diameter – speed – nbr and shape of blades – diameter – speed – nbr and shape of blades –
blade width blade width Fan design parameters influence :Fan design parameters influence : cost – power consumption – noise cost – power consumption – noise
Cooling tower fans Cooling tower fans
Noise definition Noise definition
Specify sound pressure Specify sound pressure
in dB(A) measured 1,5 meter in dB(A) measured 1,5 meter
above fan discharge above fan discharge
(per CTI std ATC – 128)(per CTI std ATC – 128)
Cooling tower fansCooling tower fansNoise Noise
Cooling tower fansCooling tower fans
ComparisonComparison - - 2000 ton tower - 196 m³/ sec @ 160 Pa 2000 ton tower - 196 m³/ sec @ 160 Pa pressure drop pressure drop
FanFandia dia
NbrNbrBladesBlades Rpm Rpm
TipTipspeed speed
SoundSoundPowerPower
Fan shaftFan shaftPower Power Fan Fan
ftft m/secm/sec dB(A)dB(A) kW kW US $ US $
1414 66270.270.
88 60.560.5 100.3100.3 59.359.3 21002100
1616 77193.193.
99 49.549.5 95.695.6 53.253.2 36003600
1818 55186.186.
88 54.254.2 9999 464613501350
00
18 *18 * 44 137137 4040 86.386.3 54.954.945004500
00
Cooling tower fansCooling tower fansFan power vs cost Fan power vs cost – 2000 ton tower – 196 m³/sec @ 160 – 2000 ton tower – 196 m³/sec @ 160 Pa Pa pressure droppressure drop
Fan dia Fan dia Tower price Tower price Fan Power Fan Power
ftft %% kWkW
1414 - - - -
1616 + 1, 25 %+ 1, 25 % - 11 % - 11 %
1818 +8 % +8 % - 22 % - 22 %
Cooling tower fansCooling tower fansComparison - Comparison - 5000 ton tower - 375 m³/ sec @ 160 Pa 5000 ton tower - 375 m³/ sec @ 160 Pa pressure droppressure drop
FanFandia dia
Nbr Nbr BladeBlade
ss Rpm Rpm Tip Tip speed speed
SoundSoundPowerPower
Fan Fan shafshaf
ttPower Power Fan Fan
ftft m/secm/sec dB(A)dB(A) kW kW US $ US $
2222 66 226226 44.244.2 106.3106.3 106.3106.3 95009500
2626 99104.104.
88 43.543.5 97.997.9 87.187.126002600
00
2626 66 89.789.7 37.237.2 90.690.6 104.2104.260006000
00
2828 66 82.682.6 36.936.9 9090 102.3102.365006500
00
Cooling tower fansCooling tower fansFan power – noise vs cost - Fan power – noise vs cost - 5000 ton tower – 5000 ton tower – 375 m³/ sec @ 160 Pa pressure drop375 m³/ sec @ 160 Pa pressure drop
FanFandia dia
TowerTowerprice price
PowePower r
SoundSoundPower Power
ftft %% kWkW dB (A)dB (A)
2222 106.3106.3
2626 + 7 %+ 7 % - 18 - 18
% % 97.997.9
2626 20%20% -2%-2% 90.690.6
2828 + 22% + 22% -4%-4% 9090
Obtain the required quality Obtain the required quality Fan stacksFan stacks
Fan stacks Fan stacks
Material Material Height : 7– 10 ft - …Height : 7– 10 ft - …
Material : Class 1 – flame spread rating 25Material : Class 1 – flame spread rating 25 (Class II and Class III = Cheaper !)(Class II and Class III = Cheaper !)
UV resistance (gelcoat 20 mil).UV resistance (gelcoat 20 mil).
Access door or removable panel Access door or removable panel
Assembly hardware SST Assembly hardware SST
Fan stacksFan stacks
Make sure fan deck floor opening matches Make sure fan deck floor opening matches fan cylinderfan cylinder
Smooth air inletSmooth air inlet
Fan tip clearance : 0,5% fan diaFan tip clearance : 0,5% fan dia
Obtain the required qualityObtain the required qualityAir inlet louvers Air inlet louvers
Water stays in… Sunlight stays out!
Air inlet louvers Air inlet louvers
Single pass FRP Blade louversSingle pass FRP Blade louvers
Waterdroplets tend to splash out when fans Waterdroplets tend to splash out when fans are shut off. are shut off.
Sunlight still enters the cooling tower basin !Sunlight still enters the cooling tower basin !
Air inlet louversAir inlet louvers
Two pass PVC air inlet louversTwo pass PVC air inlet louvers
Minimise splash-out Minimise splash-out
Direct sunlight is blocked from the water Direct sunlight is blocked from the water inside the tower and reducing the potential inside the tower and reducing the potential for algae formation ! for algae formation !
Minimum pressure drop Minimum pressure drop
Two Pass Air inlet louversTwo Pass Air inlet louvers
Typical two pass air inlet louvers Typical two pass air inlet louvers
Obtain the required quality Obtain the required quality Drift eliminatorsDrift eliminators
Obtain the required quality Obtain the required quality
Drift eliminatorsDrift eliminators
Drift rates : 0,01 to 0,0005 % of tower flow Drift rates : 0,01 to 0,0005 % of tower flow raterate
Drift rate function of type DE, air velocity, Drift rate function of type DE, air velocity, water loading and spray nozzle types, …water loading and spray nozzle types, …
Drift eliminators Drift eliminators Quality Quality
Drift rate dependends on: Drift rate dependends on:
Waterloading Waterloading Air velocity Air velocity Spray nozzle arrangement Spray nozzle arrangement
Drift eliminators Drift eliminators
Efficiency comparisonEfficiency comparison
Drift eliminators Drift eliminators Efficiency confirmationEfficiency confirmation
Ask your cooling tower supplier names Ask your cooling tower supplier names manufacturer of DEmanufacturer of DE
Demand independent test certifications Demand independent test certifications according to accepted standardsaccording to accepted standards
Air passes through area with minimum resistanceAir passes through area with minimum resistance
Air bypass reduces cooling effectAir bypass reduces cooling effect Water loss because of higher air velocityWater loss because of higher air velocity
Drift eliminators Drift eliminators Execution on siteExecution on site
Drift lossesDrift losses
Design considerations : air sealsDesign considerations : air seals
Cooling Towers FillCooling Towers FillObtain the right qualityObtain the right quality
PerformancePerformance
Cooling Tower FillCooling Tower Fill
Film Fill Design ConsiderationsFilm Fill Design Considerations
Cooling Tower FillCooling Tower Fill
Vertically Offset Flute PVC Film Fill
Cooling Tower FillCooling Tower Fill
Vertically Fluted PVC Film Fill
Cooling Tower FillCooling Tower Fill
PVCPVC Fill spacing: min 19 mmFill spacing: min 19 mm Fill thickness: 10 – 20 nils before formationFill thickness: 10 – 20 nils before formation Flamability (ASTM E84 – max 5)Flamability (ASTM E84 – max 5) Designed to accomodate operational and Designed to accomodate operational and
specified Live loadspecified Live load
Cooling Tower FillCooling Tower Fill
Cooling Towers for District CoolingCooling Towers for District Cooling
Cooling Towers for District CoolingCooling Towers for District Cooling
Obtain the specified and correct Obtain the specified and correct
quality level !quality level !
Thank youThank you
Georges HoeterickxGeorges Hoeterickx