Integrating Optimized Economizers in Your Data Center Design to Leverage the Advantages of “Free Cooling”
Integrating Optimized Economizers in Your Data Center Design to Leverage the
Advantages of “Free Cooling”
Emerson Network Power –An organization with established customers
• Emerson Network Power overview• Integrating Optimized Economizers in Your Data Center
Design to Leverage the Advantages of “Free Cooling,” Ron Spangler, Senior Product Manager, Liebert Precision Cooling, Emerson Network Power
• Bay Area Internet Solutions Delivers Efficiency Without Compromise
• Question and Answer session
Presentation topics
Integrating Optimized Economizers in Your Data Center Design to Leverage the Advantages of “Free Cooling”
Ron SpanglerSenior Project ManagerLiebert Precision CoolingEmerson Network Power
Free-cooling options
1. Air-cooled chiller with economizer(not commonly available in the U.S.)
2. Air-cooled chiller with drycooler for free-cooling3. Water-cooled chiller with economizer on cooling tower
(water-side economizer)4. Outside air introduced directly into the data center
CRAH units with outdoor chiller
6
OutdoorChiller
Liebert CW
45ºF
55ºF
CRAH units with outdoor chiller with drycooler for free-cooling
7
OutdoorChiller
Liebert CW
CRAH units with outdoor chiller
8
EvaporativeCoolingTower
Chiller
pumppump 85ºF
95ºF
45ºF
55ºF
Summertime
Liebert CW
CRAH units with outdoor chiller water-side economizer (low ambient)
9
EvaporativeCoolingTower
Chiller
pumppump 45ºF
55ºF
Wintertime
45ºF
Liebert CW
Mechanical system assumptions
Traditional OptimizedCRAH Return air temp, ºF 75ºF 80ºFEntering water temp, ºF 45ºF 55ºFWater temp rise, ºF 10ºF 15ºFCRAH supply air temp, ºF 55ºF 64ºFMaximum Cold-Aisle Temp, ºF 75ºF 75ºF
Notes:1. Raising return air temp increases economizer hours and increases
CRAH capacity and efficiency2. Increasing water temperature increases water-side economizer
hours3. Increasing water rise increases chiller efficiency
Water-side economizer
Water temperature = outdoor wetbulb + approach
Example 1:45ºF degrees water needed for full cooling10ºF degrees approach35ºF degrees outdoor wetbulb
Water-side economizer
Water temperature = outdoor wetbulb + approach
Example 2:55ºF degrees water needed for full cooling10ºF degrees approach45ºF degrees outdoor wetbulb
Water-side economizer
Water temperature = outdoor wetbulb + approach
55ºF leaving the chiller (entering CRAH unit)
70ºF entering the chiller10ºF degrees approachPartial free-cooling available at 60ºF,down to 45ºF degrees outdoor wetbulb
Atlanta weather profile(Wet bulb data)
Outdoor Ambient Wet Bulb- F
0
200
400
600
800
1000
1200
1400
1600
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
Water-side economizer45 F ewt, 10 F TD100% @ 11.1% hoursPartial @ 13.7% hours
Full PartialAnnu
al H
ours
of O
ccur
renc
e -H
rs
Atlanta weather profile(Wet bulb data)
Annu
al H
ours
of O
ccur
renc
e -H
rs
0
200
400
600
800
1000
1200
1400
1600
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
Full Partial
Water-side economizer55 F ewt, 15 F TD100% @ 24.7% hoursPartial @ 24.6% hours
Outdoor Ambient Wet Bulb- F
New York City weather profile(Wet bulb data)
Annu
al H
ours
of O
ccur
renc
e -H
rs
0
100
200
300
400
500
600
700
800
900
1000
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
Water-side economizer@ 45 F EWT, 10 F TD
100% @ 22.7% hoursPartial @ 19.0% hours
Full1985 hrs
Partial1663 hrs
Outdoor Ambient Wet Bulb- F
New York City weather profile(Wet bulb data)
Annu
al H
ours
of O
ccur
renc
e -H
rs
0
100
200
300
400
500
600
700
800
900
1000
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
Partial818 hrs
Water-side economizer@ 55 F EWT, 15 F TD
100% @ 41.6% hoursPartial @ 9.3% hours
Full3648 hrs
Outdoor Ambient Wet Bulb- F
Energy reductions
• Fan Energy Reduction– ~ 50% reduction due to variable speed EC fans
• Pump Energy– Less water flow– Less system pressure drop– ~ 50% reduction in pumping power required
• Chiller Efficiency Increases– ~ 30% chiller energy savings with higher water temperatures
ASHRAE recommendations
TC 9.9 Committee
• Minimum dewpoint = 41.9ºF• Maximum dewpoint = 59ºF
Air economizer operating window weather profile (psychrometric data)
Outdoor Ambient Dry Bulb - F
Abso
lute
Hum
idity
-lb
s / l
bs
100 % RH
ASHRAEWindow
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
32 37 42 47 52 57 62 67 72 77 82 87
Air economizer operating windowweather profile (psychrometric data)
Outdoor Ambient Dry Bulb - F
Abso
lute
Hum
idity
-lb
s / l
bs
100 % RH
ASHRAEWindow
Partial
CRAH leaving air ~65FCRAH entering air ~ 82F
Air economizer operating windowweather profile (psychrometric data)
Outdoor Ambient Dry Bulb - F
Abso
lute
Hum
idity
-lb
s / l
bs
100 % RH
ASHRAEWindow
Partial
Air economizer operating windowweather profile (psychrometric data)
Outdoor Ambient Dry Bulb - F
Abso
lute
Hum
idity
-lb
s / l
bs
100 % RH
ASHRAEWindow
Partial
Air economizer operating windowweather profile (psychrometric data)
Outdoor Ambient Dry Bulb - F
Abso
lute
Hum
idity
-lb
s / l
bs
100 % RH
ASHRAEWindow
Partial
Total energy example: Chicago
Traditional OptimizedWater
EconomizerAir
Economizer
Total kwHRS 6,457,013 4,331,311 2,655,259 3,701,215
-32.9% -58.9% -42.7%
Air economizer strategies
Room return-air mode Outside air mode
Economizers for data centers
Air-Side• Pros
– Best in moderate climates– Initial capital cost
• Cons– Ductwork required to get air to
the space– Humidity control can be a
challenge - costly– Dust and pollen sensors are
required to minimize filter maintenance
– Hard to implement in “high density” applications
– Mildew minimization actions required
Water-Side• Pros
– Can be used in any climate– Service requirements and
complexities greatly reduced• Cons
– Series indirect piping and control more complex
– Initial capital costs
Example economizer layout
• Mixing box per CRAC unit– 0 – 10 v independent control
dampers– We will entertain controlling mixing
boxes by others.
Air economizer standard region of operationAir economizer standard region of operation
IT OEM (server manufacturer) concerns with outside air economizers
• The impact of high humidity• The impact of low dew point• The impact of contamination – particulate and / or
gaseous.– Published ASHRAE whitepaper, “Gaseous and Particulate
Contamination Guidelines for Data Centers”• Many of the failure modes would be additive over time,
not instantaneous
IT OEM concerns
• The impact of high humidity– Above 55% RH the impact of air borne salt becomes measurable– This failure mode is additive over time
• Impact of low humidity– Electrostatic Discharge (ESD) can damage hardware– A hard drive or tape drive may generate electrostatic discharges
when the dew point is below 5 deg C (41F)
IT OEM concerns
• The impact of contamination – particulate and / or gaseous.– Particulate contamination is solvable via filtration - MERV 13 – Gaseous contamination is very costly to filter
• The gaseous contamination should be within the modified ANSI/ISA-71.04-1985 severity level G1 for copper and silver corrosion of less than 300C/30days
• Failure modes – Copper creep corrosion on RoHS-compliant circuit boards and
the corrosion of silver metallization in miniature surface mounted components• This failure mode is additive over time
Customizing CRAH performance
• Coils w/ higher ΔT / lower GPM– Coils can be customized for lower flow rates– Optimizing chiller can result in trade-offs
• Designed for higher EAT (> 85 F)– Standard rating point 75 F– High SHR
• High efficiency filtration (> 30%)– Offering with MERV 11 (65%) & MERV 13 (85%) and pre-filters– Upflow units can provide up to 2” external static
Bay Area Internet Solutions Delivers Efficiency Without Compromise
35
Q & A
Ron SpanglerSenior Project ManagerLiebert Precision CoolingEmerson Network [email protected]
Thanks for joining us!
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