applying precision air conditioning systems
DESCRIPTION
Applying Precision Air Conditioning Systems. Canatal International Inc. Introduction. Application of Precision Air Conditioning Data Centers Switching Stations Co-Location Facilities. Topics of Discussion. Servers / Switch Gear Temperature & Humidity Control Air Distribution Redundancy - PowerPoint PPT PresentationTRANSCRIPT
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Applying Precision Air Conditioning Systems
Canatal International Inc.
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Introduction
Application of Precision Air Conditioning Data Centers Switching Stations Co-Location Facilities
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Topics of Discussion Servers / Switch Gear Temperature & Humidity Control Air Distribution Redundancy Alternating Cold Aisle, Hot Aisle Perforated Tile Capacity Design & Planning Stage Maintenance
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Servers / Switch Gear
Smaller, More PowerfulDriven by semi-conductor capacity More transistors on a chip More power consumption per chip More heat generation
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New ASHRAE Document
“Thermal Guidelines for Data Processing Environments” Equipment Environment Specifications Facility Temperature & Humidity Measurement Equipment & Facility Layout Equipment Manufacturers Heat & Airflow
Reporting
Available @www.ashrae.org, Item Number 90431, or D90431
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“Thermal Guidelines for Data Processing Environments”
Equipment Environment Specifications
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“Thermal Guidelines for Data Processing Environments”
Equipment Environment Specifications
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ASHRAE Class 1 Operating Conditions
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ASHRAE Class 1 Operating Conditions
Increase Equipment Failures
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ASHRAE Class 1 Operating Conditions
Increase HVAC Energy Use
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“Thermal Guidelines for Data Processing Environments”
Facility Temperature & Humidity Measurement
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“Thermal Guidelines for Data Processing Environments”
Equipment & Facility Layout Recommended Airflow Protocol for Computer
Equipment
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“Thermal Guidelines for Data Processing Environments”
Equipment & Facility Layout Recommended Airflow Protocol for Computer
Equipment
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“Thermal Guidelines for Data Processing Environments”
Equipment & Facility Layout Recommended Airflow Protocol for Computer
Equipment
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“Thermal Guidelines for Data Processing Environments”
Equipment Manufacturers Heat & Airflow Reporting
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Server / Switch Gear
Back View Front View
1U (1.70” H) Server
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Server / Switch Gear
Back View Front View
2U (3.50” H) Server
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Server / Switch Gear
Back View Front View
4U (6.80” H) Server
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Server / Switch Gear
Back View Front View
5U Server – Tower Configuration
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Server / Switch Gear
Back View Front View
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Heat Density Trends
Source: Uptime Institute
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What is wrong with this picture?
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What is wrong with this picture?
1a 1b2
34
5
1a, 1b Cold aisles. 1a has less airflow then 1b - WHY?2 Hot aisles3 Top of hot aisle (from right to left – warm to hot)4 Insufficient cold air and recirculation from hot aisle to cold aisle 5 Mixed return air path
22
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External re-circulation: Top 1/3 portion likely to have higher failure rate
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• Internal re-circulation:• Add blanking panels to eliminate the problem
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Positioning of PAC units Parallel or Perpendicular to aisles
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Temperature Control
Challenges Hot Spots / Hot Zones / Hot Room Uneven heat load on the floor space Fluctuating heat loads Initial low loads
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Temperature Control
Servers/Switches generate sensible heat Utilize Precision Air Conditioning
Systems with high sensible heat ratios Unwanted dehumidification is a waste of
energy and money
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Humidity Control
Independently operated units will fight- simultaneously humidify and dehumidify
Wasting energy and money Units should work together as a Team
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Air Distribution
Raised Floor System Generally more flexible Easy to move perforated tilesOverhead System Ducted or Plenum Make the last length of duct flexible to
enable movement of discharge grilles
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Air Distribution
Deliver Cool Air to the Heat Source
Eliminate Short Circuiting Anytime air returns to the PAC without
passing through heat generating servers, routers, switches etc.
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Air Distribution
Short Circuiting - Common Causes Obstructions to airflow Air Leakage Location of discharge grilles and
perforated tiles
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Air Distribution – Obstructions
Raised Floor System Electric cable trays,
especially with shallow floor heights
Water damp
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Air Distribution – ObstructionsPractice Recommendations for Position
Equipment Racks & Cabinets Power Distribution Unit (PDU) cables should
run under the “Cold Aisles” Cable trays for telecom cablings should locate
under the “ Hot Aisles” Cabinet should be aligned with one edge along
the edge of the cold aisle floor tile Floor tile cuts should be no larger then
necessary to minimize air pressure loss
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Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Power Distribution Unit (PDU) cables should run under the “Cold Aisles”
Cable trays for telecom cablings should locate under the “ Hot Aisles”
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Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Power Distribution Unit (PDU) cables should run under the “Cold Aisles”
Cable trays for telecom cablings should locate under the “ Hot Aisles”
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Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Power Distribution Unit (PDU) cables should run under the “Cold Aisles”
Cable trays for telecom cablings should locate under the “ Hot Aisles”
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Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Cabinet should be aligned with one edge along the edge of the cold aisle floor tile
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Air Distribution – Obstructions
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Air Distribution – Oversized Openings
Practice Recommendations for Position Equipment Racks & Cabinets
Floor tile cuts should be no larger then necessary to minimize air pressure loss
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Air Distribution – Oversized Openings
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Air Distribution ObstructionsMaximize Floor Height Floor height restricts air flow volume High airflow velocities under the floor
can negate static pressure differentials and entrain air from above to below
May need scoops
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Air Distribution Obstructions
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Air Distribution Obstruction
Overhead System Light fixtures, overhead cable trays Equipment that is taller than the
discharge plenum
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Air Flow Obstruction
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Air Distribution – Obstructions
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Air Distribution – Obstructions
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Air Distribution – Air LeakageRaised Floor System Behind the PAC unit Improper Wire/Cable openings
- remove one tile to run wires Around the perimeter of room
Adversely effects the under floor static pressure hindering the control of airflow
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Air Distribution – Air Leakage
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Cleanliness and Proper Vapor Barrier in Subfloor
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What is the right distancefrom PAC to the 1st Rack
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None-Direction Airflow
Pressure = Static Pressure + Velocity Pressure
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Perform Better
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Air Distribution – Air LeakageOverhead System No shut off dampers on redundant units Back draft dampers or motorized
discharge dampers with timers
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Air Distribution – Airflow PatternRaised Floor System Perforated tile quantity and layout Perforated tiles too close to the PAC 3 foot clearance above computer racks Drop ceiling = return air plenum
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Air Distribution – Airflow Pattern
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Air Distribution – Airflow Pattern
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Air Distribution – Airflow PatternOverhead System Discharge diffuser too close to the PAC Air discharge from one unit enters the
return air of another
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Air Distribution – Airflow Pattern
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Redundancy
N+1 PAC Unitsi.e. 20 ton load, three 10 ton units
Only one pump on glycol/water loop Multiple feeds to PAC units, but only
one breaker for all rooftop condensers
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Redundancy of Airflow
Can air reach each part of the room from more than one unit?
If the answer is no, then N+1 may be negated
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Alternating Cold Aisle, Hot AisleComputer Equipment Air Flow Pattern In the front, out the back
Racks face each other along one aisle Backs face each other on alternate aisle
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Alternating Cold Aisle, Hot Aisle
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Alternating Cold Aisle, Hot Aisle
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Alternating Cold Aisle, Hot Aisle
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Air Distribution – Airflow PatternRaised Floor System Controlling the Return Air
Drop ceiling = return air plenum
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Air Distribution – Airflow Pattern
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Cost Effective Solution
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Cooling Capacity – One Tile
Perforated Tile Cooling Capacity
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Cooling Capacity – One Tile
Directly dependent on the airflow volume deliver through each tile
Air volume dependent on static pressure under the floor
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Cooling Capacity – One Tile
One 2’ x 2’ Perforated Tile Typical Airflow
600 cfm @ 0.10” w.c.200 cfm @ 0.02” w.c.
Thus, leakage and too many perf. tiles will reduce static pressure and reduce the ability to control air flow
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Cooling Capacity – One Tile
Maintain high sensible heat ratio AT 72˚F, 50%RH or 68˚F, 50%RH,
excessive condensation occurs after a 17˚F temperature drop
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Cooling Capacity – One Tile
29.921 inHg0 ft
F 45 50 55 60 65 70 75 80 85 90
0.002lbm/lbm
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.02
0.022
0.024
0.026
0.028
1
Btu/lbm 45
40
35
30
25
20
15
10
ft^3/lbm 12.6 13.2 13.8
17˚F
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Cooling Capacity – One Tile
Cooling Capability
600 cfm x 17˚F x 1.08 = 11,000 Btuh
Airflow volume critical to cooling capacity
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Cooling Capacity – Per Rack
Four foot wide aisles 22,000 Btuh sensible cooling per two
feet of aisle With racks on both sides of the aisle, the
heat load is 3,200 Watts per two feet of racking
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Downflow Front Discharge
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Design & Planning Stage Capacity and placement of PAC Room Geometry
Initial & final room layoutInitial & final load
Factors affecting air flow distributionPlenum static pressureObstructions beneath plenum Configuration to prevent air mixing
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Design & Planning Stage Mechanical system selection:
Air / water cool Refrigeration/water piping layout Keep it simple
Noise concerns: Local or remote compressor Condenser / condensing
Energy factor Dual / Free Cooling NSB, increase of useable floor space Free cooling system
Risk factor Chilled water /water cooled system
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Maintenance
Commissioning of basic systemsRefrigeration, electrical, blower RPM, etc.
Programming of controllerConfigure alarm responses
Train End-user Follow Maintenance Program
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Maintenance
Common Deficiencies Dirty or blocked filters Undercharged DX systems Un-calibrated or damaged sensors Poor water flow, partially closed valves
or other piping obstructions Chilled water supply temp. (49 - 54˚F)
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Thank You