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					 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

                              45ºF




                                     Outdoor
                                     Chiller

 Liebert CW



                              55ºF


                                               6
CRAH units with outdoor chiller with
drycooler for free-cooling




                                       Outdoor
                                       Chiller

 Liebert CW




                                                 7
CRAH units with outdoor chiller
                 pump             pump
                                             85ºF Summer
                                                   time

                 45ºF



                                                  Evaporative
                                                  Cooling
                                                  Tower
 Liebert CW
                            Chiller
                55ºF                  95ºF


                                                            8
CRAH units with outdoor chiller water-side
economizer (low ambient)
                 pump                pump
                                                45ºF Winter
                                                      time
                        45ºF




                                                      Evaporative
                                                      Cooling
                                                      Tower
 Liebert CW
                               Chiller
                                         55ºF


                                                                9
Mechanical system assumptions

                                       Traditional   Optimized
  CRAH Return air temp, ºF                75ºF          80ºF
  Entering water temp, ºF                 45ºF          55ºF
  Water temp rise, ºF                     10ºF          15ºF
  CRAH supply air temp, ºF                55ºF          64ºF
  Maximum Cold-Aisle Temp, ºF             75ºF          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:
45ºF degrees water needed for full cooling
10ºF degrees approach
35ºF degrees outdoor wetbulb
Water-side economizer


Water temperature = outdoor wetbulb + approach



Example 2:
55ºF degrees water needed for full cooling
10ºF degrees approach
45ºF degrees outdoor wetbulb
Water-side economizer


Water temperature = outdoor wetbulb + approach

55ºF leaving the chiller (entering CRAH unit)

70ºF entering the chiller
10ºF degrees approach
Partial free-cooling available at 60ºF,
down to 45ºF degrees outdoor wetbulb
Atlanta weather profile
(Wet bulb data)

                                    1600
 Annual Hours of Occurrence - Hrs




                                    1400
                                               Water-side economizer
                                               45 F ewt, 10 F TD
                                    1200       100% @ 11.1% hours
                                               Partial @ 13.7% hours
                                    1000


                                    800


                                    600


                                    400


                                    200
                                                                              Partial
                                      0
                                                                    Full
                                           0    5   10   15   20   25   30   35   40   45   50   55   60   65   70   75   80   85

                                                              Outdoor Ambient Wet Bulb- F
Atlanta weather profile
(Wet bulb data)
 Annual Hours of Occurrence - Hrs


                                    1600

                                               Water-side economizer
                                    1400
                                               55 F ewt, 15 F TD
                                    1200       100% @ 24.7% hours
                                               Partial @ 24.6% hours
                                    1000


                                    800


                                    600


                                    400


                                    200                                       Full          Partial
                                      0
                                           0    5   10   15   20   25   30   35   40   45   50   55   60   65   70   75   80   85

                                                              Outdoor Ambient Wet Bulb- F
New York City weather profile
(Wet bulb data)
 Annual Hours of Occurrence - Hrs


                                    1000
                                               Water-side economizer
                                    900
                                               @ 45 F EWT, 10 F TD
                                    800         100% @ 22.7% hours
                                                Partial @ 19.0% hours
                                    700

                                    600

                                    500
                                                                           Partial
                                    400                                    1663 hrs
                                    300

                                    200
                                                           Full
                                    100                    1985 hrs
                                      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
(Wet bulb data)

                                               Water-side economizer
 Annual Hours of Occurrence - Hrs


                                    1000
                                               @ 55 F EWT, 15 F TD
                                    900         100% @ 41.6% hours
                                                Partial @ 9.3% hours
                                    800

                                    700

                                    600

                                    500                                        Partial
                                    400                                        818 hrs
                                    300

                                    200                      Full
                                    100                      3648 hrs
                                      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)
                                0.035
Absolute Humidity - lbs / lbs




                                 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      72   77   82    87

                                                       Outdoor Ambient Dry Bulb - F
Air economizer operating window
weather profile (psychrometric data)
Absolute Humidity - lbs / lbs




                                                                            100 % RH
                                CRAH leaving air ~65F
                                CRAH entering air ~ 82F


                                         ASHRAE
                                         Window
                                                                        Partial




                                         Outdoor Ambient Dry Bulb - F
Air economizer operating window
weather profile (psychrometric data)
Absolute Humidity - lbs / lbs




                                                                   100 % RH




                                ASHRAE
                                Window
                                                               Partial




                                Outdoor Ambient Dry Bulb - F
Air economizer operating window
weather profile (psychrometric data)
Absolute Humidity - lbs / lbs




                                                                   100 % RH




                                ASHRAE
                                Window
                                                               Partial




                                Outdoor Ambient Dry Bulb - F
Air economizer operating window
weather profile (psychrometric data)
Absolute Humidity - lbs / lbs




                                                                   100 % RH




                                ASHRAE
                                Window
                                                               Partial




                                Outdoor Ambient Dry Bulb - F
  Total energy example: Chicago


                                          Water          Air
              Traditional   Optimized   Economizer   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                              Water-Side
•   Pros                                •   Pros
    – Best in moderate climates             – Can be used in any climate
    – Initial capital cost                  – Service requirements and
•   Cons                                      complexities greatly reduced
    – Ductwork required to get air to   •   Cons
      the space                             – Series indirect piping and control
    – Humidity control can be a               more complex
      challenge - costly                    – Initial capital costs
    – Dust and pollen sensors are
      required to minimize filter
      maintenance
    – Hard to implement in “high
      density” applications
    – Mildew minimization actions
      required
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/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 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

				
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