The Science Behind Airflow Management Best Practices
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Transcript of The Science Behind Airflow Management Best Practices
The Science Behind Airflow
Management Best Practices
Lars Strong, P.E., Upsite Technologies
Mark Seymour, Future Facilities
Airflow Management Awareness Month
June 1, 2016
Identify Your Opportunity
© Upsite Technologies, Inc.6/2/2016 2
There are two types of computer rooms
1. Those without IT equipment intake air temperature problems
• Improving AFM enables them to be more efficient
2. Those with IT equipment intake air temperature problems
• Improving AFM solves intake air temperature problems (hot
spots and cold spots) and enables them to be more efficient
• More efficient results in: lower OPEX, deferred CAPEX,
increased cooling capacity
Why Airflow Management
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Total Load
IT LoadPUE =
Mechanical plant + cooling fans: 35% of total load, 73% of non IT Load
BYPASS AIRFLOW CLARIFIED
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Definition of Bypass Airflow
Any cooling air that does not pass through IT equipment before returning to a cooling unit
Bypass flow rate (CFM) = total cooling supply flow rate (CFM) – total IT equipment flow rate (CFM)
© Upsite Technologies, Inc.
ΔT Through IT Equipment
UPS load (kW) x avg CFM/kW = Total IT CFM
IT Equipment Required Flow Rate
IT
Equipment
Delta T (deg F)
15° 20° 25° 30° 35° 40°
Required
flow rate (CFM/kW)
211 158 126 105 90 79
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Bypass Airflow Clarified
Typical existing conditions
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Bypass Airflow Clarified
After AFM improvements
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Bypass Airflow Clarified
Optimized
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Upsite’s 4 R’s of Airflow Management™
A holistic approach
An iterative process
‘check in’ at the room level
after making any
adjustments
6/2/2016 10
Watch video at:upsite.com/resources/airflow-management/
© Upsite Technologies, Inc.
Airflow Management Best Practices
Gone Wrong, What We Can Learn
Mark Seymour
Future Facilities 11
This presentation illustrates some of the classic actions in a
data center that can create airflow management issues
The intent is to reveal:
• Why considering airflow is important
• That good practice is just that – it’s not a guarantee
• Engineering simulation is used to illustrate airflow that is
otherwise unseen and enabling proactive operational
management
• Airflow management applies to both the rack/cabinet level
and the room level
Introduction
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Energy efficiency of the
cooling system can be
undermined by
• Negative flow
o Often through perforated tiles
near the cooling unit
• By-pass
o Can overshoot IT or pass
through unmanaged leakage.
E.g. cable penetrations
• Recirculation
o Occurs in the rack as well as
the room is important
Common issues
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CABLE PENETRATIONS & LEAKAGE
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Unmanaged cable
penetrations
Typically installed in
raised floor in rear if the
cabinet
Installing cable
management is an easy
win but care should be
taken to ensure the
cooling is not in use
Leakage Paths
Watch for leakage paths
• Under the cabinet
• Over the cabinet (through containment)
• Between cabinets
• End of rows (through containment)
• Through Cooling Units on standby
• Similarly in the rack
o Under
o Over
o Between
o Around equipment
o Through IT equipment that is off
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Cable Penetration Seals
Cable Penetration Management
Why practice it?
• Stop air leaking out of the
cable penetrations
• Increase the pressure in
the raised floor plenum
• Stop bypass cooling down
the hot return air
• Force more air out of the
perforated tiles and grates
in front of the IT
equipment
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Hot Aisle / Cold
Aisle
Mix of Equipment
Size: 1,066 sq. ft.
Cooling: 55.6 tons
(196 kW)
Load: 152 kW
Example Room
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ASHRAE Temperature Compliance
One rack has inlet temperatures above the ASHRAE
Temperature Compliance recommended range
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Using simulation we can investigate the impact of adding
brush seals to the cable penetrations:
Modeling of Penetration Seals
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Static Pressure
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Perforated Tile Flow
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ASHRAE Temperature Results
Comparison
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Improving raised floor open area
management reveals need to improve
rack airflow management
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Why Did the Room Get Worse?
With Brush
SealsNo Seals
Improving rack airflow management with blanking
panels, rail seals, and under rack panels will bring IT
intake air temperatures back into compliance
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Sealing holes in the floor are still the best practice
It is critical to apply best practices to sealing the
cabinet at the same time.
Final engineering simulation image would reveal
optimized cooling with no exhaust air recirculation
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Equipment Configuration
Consider a cabinet housing
a blade system and 3 1U
servers
• Does it matter how the 2
equipment types are
installed in this cabinet?
• Option 1 – Three 1U
servers placed on top of a
BladeCenter H
3kW Blade
Enclosure
3 x 1U 275W
Servers
15oC / 59°F Supply Air
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Equipment Configuration
Base Configuration – Option 1
Recirculation
under cabinet
Maximum inlet temperature
oC (°F)
Blade 27.1 (80.8)
Server1 19.6 (67.3)
Server2 19.7 (67.5)
Server3 18.9 (66.0)
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Equipment Configuration
Option: 1U servers under blade
Maximum inlet temperature
oC (°F)
Blade 18.1 (64.6)
Server1 19.1 (66.4)
Server2 20.9 (69.6)
Server3 21.8 (71.2)
Recirculation from
1u servers is cooler
Recirculation of this nature can occur
whether or not the data center is
contained. The solution is blocking the
under rack airflow.
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AISLE CONTAINMENT
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Consider two rows of equipment with full cold aisle
containment:
Cold Aisle Containment
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Containment Measured
Warmer Air
Supply
No change
Colder Air
Supply
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Simulation shows what is happening:
• There is a lack of available airflow
• Uncontained, the additional air required recirculates via the room over the top of the cabinets. Consequently it mixes and so is colder than the air in the hot aisle
• Contained, the additional air recirculates directly from the back of the cabinets and, without any mixing, it is hotter.
Simulation Explains All
Uncontained
Contained
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COOLING UNITS
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More efficient (up to 30%)
Easily controlled (0-10V
signal)
Longer life and reduced
maintenance
Improved airflow through
the CRAC/CRAH
Reduced noise
Benefits of EC fans?
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Air Distribution
EC Plug Fans vs Traditional Blowers
Blower
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Traditional BlowersLowered EC Plug Fans
The different types of fans distribute air in different ways
The Effect on Airflow
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6,727ft² of floor space
200+ Cabinets
800kW Cooling Capacity at
N+2
Test Facility
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Airflow distribution patterns look very different.
How has this affected the available cooling?
Grille Flow
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0
10
20
30
40
50
60
70
80
90
100
1 2 3 4 5 6 7 8 9 10 11 12 13
Pote
ntia
l Coo
ling
(kW
)
Cold Aisle
Cooling Available per Row
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Reduced cooling capacity puts IT at risk of thermal
shutdown
Immediate Issues
Aisle 4 cooling
reduced 21kW
64 Blades now at
risk
Aisle 5 cooling
reduced 15kW
30 Proliants now at
risk
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Immediate Issues
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Upsite's 4 R's of Airflow Optimization provide a guide for
implement changes and achieving the greatest benefits in
your data center.
“Efficiency can’t be purchased,
it has to be managed”
Julian Kudritzki
- The Uptime Institute
Airflow management is essential for optimizing capacity
and efficiency of the entire data center
Good practices are often beneficial but should be
undertaken with due diligence
Airflow is invisible, therefore the hardest thing to manage
in a data center
Actions for one scenario may be beneficial while in
another counter productive – e.g. total containment in an
over-provisioned scenario compared with an under-
provisioned scenario.
Engineering simulation can visualize and help guide
airflow management choices
Apply the 4 R’s Methodology to Airflow Management
Summary & Conclusions
© Upsite Technologies, Inc.6/2/2016 41
June 8: 5 Myths of Data Center ContainmentPresented by Lars Strong, P.E.
June 15: How IT Decisions Impact Facilities: The Importance of Mutual UnderstandingPresented by Ian Seaton and Lars Strong, P.E.
June 22: The 4 Delta T’s of Airflow ManagementPresented by Lars Strong, P.E.
Register at upsite.com/airflow-management-awareness-month
Upcoming Schedule
© Upsite Technologies, Inc.6/2/2016 42
Thank you!
@UpsiteTech
blog.upsite.com
On LinkedIn
Lars Strong, P.E.
Senior Engineer, Upsite
Follow Upsite for the latest
news and information on
data center AFM.
Mark Seymour
Senior Engineer, Future