Integrating Optimized Economizers in Your Data Center Design to Leverage the Advantages of “Free Cooling�
Emerson Network Power – An organization with established customers
Presentation topics • 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
Integrating Optimized Economizers in Your Data Center Design to Leverage the Advantages of “Free Cooling� Ron Spangler Senior Project Manager Liebert Precision Cooling Emerson 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-cooling 3. 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 45ยบF
Outdoor Chiller Liebert CW
55ยบF
6
CRAH units with outdoor chiller with drycooler for free-cooling
Outdoor Chiller Liebert CW
7
CRAH units with outdoor chiller pump
pump
85ยบF Summer time
45ยบF
Evaporative Cooling Tower
Liebert CW
Chiller 55ยบF
95ยบF
8
CRAH units with outdoor chiller water-side economizer (low ambient) pump
pump
45ยบF Winter time
45ยบF
Evaporative Cooling Tower
Liebert CW
Chiller 55ยบF
9
Mechanical system assumptions
CRAH Return air temp, ºF Entering water temp, ºF Water temp rise, ºF CRAH supply air temp, ºF Maximum Cold-Aisle Temp, ºF
Traditional 75ºF 45ºF 10ºF 55ºF 75ºF
Optimized 80ºF 55ºF 15ºF 64ºF 75ºF
Notes: 1. Raising return air temp increases economizer hours and increases CRAH capacity and efficiency 2. Increasing water temperature increases water-side economizer hours 3. Increasing water rise increases chiller efficiency
Water-side economizer Water temperature = outdoor wetbulb + approach
Example 1: 45ยบF degrees water needed for full cooling 10ยบF degrees approach 35ยบF degrees outdoor wetbulb
Water-side economizer Water temperature = outdoor wetbulb + approach
Example 2: 55ยบF degrees water needed for full cooling 10ยบF degrees approach 45ยบF degrees outdoor wetbulb
Water-side economizer Water temperature = outdoor wetbulb + approach 55ยบF leaving the chiller (entering CRAH unit) 70ยบF entering the chiller 10ยบF degrees approach Partial free-cooling available at 60ยบF, down to 45ยบF degrees outdoor wetbulb
Atlanta weather profile
Annual Hours of Occurrence - Hrs
(Wet bulb data) 1600
Water-side economizer 45 F ewt, 10 F TD 100% @ 11.1% hours Partial @ 13.7% hours
1400 1200 1000 800 600 400 200
Full
0
0
5
10
15
20
25
30
Partial 35
40
45
50
55
Outdoor Ambient Wet Bulb- F
60
65
70
75
80
85
Atlanta weather profile
Annual Hours of Occurrence - Hrs
(Wet bulb data) 1600
Water-side economizer 55 F ewt, 15 F TD 100% @ 24.7% hours Partial @ 24.6% hours
1400 1200 1000 800 600 400
Full
200
Partial
0
0
5
10
15
20
25
30
35
40
45
50
55
Outdoor Ambient Wet Bulb- F
60
65
70
75
80
85
New York City weather profile
Annual Hours of Occurrence - Hrs
(Wet bulb data) 1000
Water-side economizer @ 45 F EWT, 10 F TD 100% @ 22.7% hours Partial @ 19.0% hours
900 800 700 600
Partial 1663 hrs
500 400 300
Full 1985 hrs
200 100 0
0
5
10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
Outdoor Ambient Wet Bulb- F
New York City weather profile
Annual Hours of Occurrence - Hrs
(Wet bulb data) Water-side economizer @ 55 F EWT, 15 F TD 100% @ 41.6% hours Partial @ 9.3% hours
1000 900 800 700 600
Partial 818 hrs
500 400 300
Full 3648 hrs
200 100 0
0
5
10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
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)
Absolute Humidity - lbs / lbs
0.035 0.03
100 % RH
0.025 0.02 0.015
ASHRAE Window
0.01 0.005 0 32
37
42
47
52
57
62
67
Outdoor Ambient Dry Bulb - F
72
77
82
87
Absolute Humidity - lbs / lbs
Air economizer operating window weather profile (psychrometric data)
100 % RH
CRAH leaving air ~65F CRAH entering air ~ 82F
ASHRAE Window Partial
Outdoor Ambient Dry Bulb - F
Absolute Humidity - lbs / lbs
Air economizer operating window weather profile (psychrometric data)
100 % RH
ASHRAE Window Partial
Outdoor Ambient Dry Bulb - F
Absolute Humidity - lbs / lbs
Air economizer operating window weather profile (psychrometric data)
100 % RH
ASHRAE Window Partial
Outdoor Ambient Dry Bulb - F
Absolute Humidity - lbs / lbs
Air economizer operating window weather profile (psychrometric data)
100 % RH
ASHRAE Window Partial
Outdoor Ambient Dry Bulb - F
Total energy example: Chicago
Total kwHRS
Traditional
Optimized
Water Economizer
Air Economizer
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
Water-Side •
– Best in moderate climates – Initial capital cost
•
– Can be used in any climate – Service requirements and complexities greatly reduced
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
Pros
•
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 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/ISA71.04-1985 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 Spangler Senior Project Manager Liebert Precision Cooling Emerson Network Power Ron.Spangler@Emerson.com
Thanks for joining us! • Register for our next Webcast on April 21, “Efficiency Without Compromise: Optimizing Data Center Infrastructure to Reduce Cost and Deliver High Availability” • Follow @EmrsnNPDataCntr on Twitter or visit the EmersonNetworkPower YouTube Channel