KURT JÜRGEN PLÖTNER, Director Global Product Sales & Marketing, STULZ GmbH
New Design Trends for Air Conditioning Installations in Data CentresBest Practice
for trouble-free and efficient operation of
the Data Center cooling systemKURT JÜRGEN PLÖTNER
Director Global Product Sales & MarketingSTULZ GmbH
May 2009Best Practice - Data Centre Cooling1New Design Trends for Air Conditioning Installations in Data CentresBest Practice
• What is precision air conditioning ?
• Why energy efficient precision air conditioning ?
• Requirements of the IT-equipment and the data-centre
• Elements influencing the data-centre cooling efficiencyMay 2009Best Practice - Data Centre Cooling2New Design Trends for Air Conditioning Installations in Data CentresWhat is Precision Air Conditioning ?May 2009Best Practice - Data Centre Cooling3New Design Trends for Air Conditioning Installations in Data CentresDefinition Precision Air Conditioning (PAC) or
Computer Room Air Conditioning (CRAC)
Close control units are able to maintain defined, constant and therefore
precise temperature and humidity conditions in the room. The tolerances
for room temperature and humidity are controlled in a small band.
These tolerances are usually as follows:
- Temperature: +/- 1K
- Humidity: +/- 5%
=> The units have to:
• Cool
• Reheat
• Humidify
• DehumidifyMay 2009Best Practice - Data Centre Cooling4New Design Trends for Air Conditioning Installations in Data CentresDefinition Precision Air Conditioning (PAC) or
Computer Room Air Conditioning (CRAC)
In addition the air is filtered with a high grade of air filter.The cooling capacity is offered typically as >90% sensible cooling
capacity – this portion of the total cooling capacity is able to reduce
the temperature.
The latent cooling capacity portion typically <10% is able to reduce
the humidity in the room – the dehumidification is a control
function.
The absorbed energy of a close control air conditioning system is used
to reduce the temperature of the room !!!
May 2009Best Practice - Data Centre Cooling5New Design Trends for Air Conditioning Installations in Data CentresCooling Capacity – What does total and net sensible
cooling capacity mean?
InputFunctionConditions98,5 kW Total
Cooling CapacityAirflow
24.000 m³/hReturn Air
24° C; 45 % r. H.
8.3 g water / kg air93,5 kW Sensible Capacity
(cooling)
and
5 kW Latent Capacity
(dehumidification)Temperature Decrease
12.0° C
and
Humidity Decrease
0.3 g / kg
Cooling Air
12.0° C; 92 % r. H.
8.0 g water / kg air5,9 kW Heat Rejection
Fan absorbed power
converts to heat87,6 kW Net Sensible
Cooling CapacityMay 2009Temperature Increase 0.8° CExample: ASD 1062 ABest Practice - Data Centre CoolingCooling Air (supply air)
12.8° C; 87 % r. H.
8.0 g water / kg air6New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Application•Air conditioning for
technical applicationsCooling capacity•4 to 200 kWMay 2009Best Practice - Data Centre Cooling•Air conditioning for
human requirements•2 to 30 kW7New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Environmental
requirements•Electronic requirements•Human requirementsSource: ASHRAE» A much smaller band has to be controlled more precisely !!
May 2009Best Practice - Data Centre Cooling8New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Sensible heat ratio•> 90 %•50 to 60 %The sensible part of the cooling capacity reduces the temperature,
while the latent part reduces the humidity. Comfort air conditioning
units use up to 50% of their capacity for dehumidification, whereas
precision air condition units convert more than 90% of their energy
into cooling capacity.
May 2009Best Practice - Data Centre Cooling9New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Temperature
control••+/- 1K+/- 3KIT-equipment only works reliable and without faults within a relatively
narrow temperature range.
Precision air conditioning units ensure optimum temperature accuracy
with maximum tolerances of +/- 1K, while comfort units can normally
deviate from the set value by as much as +/- 3K.
May 2009Best Practice - Data Centre Cooling10New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Humidity control•Controlled humidification and
dehumidification•Unregulated dehumidification
for comfortable cooling(+/- 5% relative humidity)Unlike comfort air conditioning units, precision air conditioning units can
feature proportional controlled and accurate humidification (+/- 5%), as
too much humidity can lead to corrosion and condensation, while too little
can cause static charges, data loss and damage to hardware.May 2009Best Practice - Data Centre Cooling11New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Airflow and
filtration•
•200 to 300 m³/h per kW
High grade of air filtration
(minimum G4)•
•100 m³/h per kW
Low grade of air filtrationPrecision air conditioning units filter and circulate approx. 3 times the
amount of air as comfort units with the same rated capacity. That means
they reliably are able to dissipate isolated thermal loads even from distant
corners of a room.
May 2009Best Practice - Data Centre Cooling12New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Diversity of
options•High, due to individual
productionOperator controls•Technical, many parametersMay 2009Best Practice - Data Centre Cooling••Low, due to mass
productionSimple, few parameters13New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Method of
operation•Permanent operation
(8.760 hours per year)•Cyclical operation
(1.200 hours per year)Comfort air conditioning units mainly operate in summer and only a few
hours a day. By contrast, precision air conditioning units need to be
available whenever the electronic equipment to be cooled is in operation.
This is normally the case for 24 hours a day, 365 days a year.
May 2009Best Practice - Data Centre Cooling14New Design Trends for Air Conditioning Installations in Data CentresPrecision and comfort A/C-units comparison
Summary:
If you have to cool electronic equipment that has to be in operation
24 hours a day and 365 days a year – the only choice is a precision
air conditioning unit. Only a precision air conditioning unit is able to
control the room temperature and humidity exactly according to the
demand of the IT-equipment.May 2009Best Practice - Data Centre Cooling15New Design Trends for Air Conditioning Installations in Data CentresWhy Energy Efficient Precision Air Conditioning?May 2009Best Practice - Data Centre Cooling16New Design Trends for Air Conditioning Installations in Data CentresThe Need for Energy Efficient Data Centres
Some headlinesIn general: One 20 MW data-centre and 80.000 households
(“western standard”) consume the same energy a year.
Germany: Altogether approximately 50.000 server rooms and
data-centres consumed 10,1 TWh (= 10.100.000.000 kWh) in
2008 (equivilant to 6.4 million tons of CO2).
Worldwide: It is estimated that server rooms and data-centres
consumed about 123 billion kWh in 2005. If the status quo
continues, by 2011, data-centres will consume about 216
billion kWh of energy. This is approx. 1 to 1,3% of the total
power consumption.
May 2009Best Practice - Data Centre Cooling17New Design Trends for Air Conditioning Installations in Data CentresThe Need for Energy Efficient Data CentresMay 2009Best Practice - Data Centre Cooling18New Design Trends for Air Conditioning Installations in Data CentresThe Need for Energy Efficient Data Centres
Considering the
„buisiness-as-usual“
scenario it would mean
that in 2013 in Germany
about 2,2 billion € have to
be paid for energy in datacentres.
Taking into account the
„moderate-efficiencyincrease“, what does
mean that an energy
saving of 10% in all datacentres is possible, the
number would be 1,4
billion €.May 2009Best Practice - Data Centre Cooling19New Design Trends for Air Conditioning Installations in Data CentresEnergy flow through the Data Centre
PUE Example:
Having a facility that uses 100.000 kW of total
power of which 80.000 kW is used to power the
IT equipment, would generate a PUE of 1.25.
DCE (DCiE) Example:
Having that same facility that uses 100.000 kW
of total power of which 80.000 kW is used to
power the IT-equipment, would generate a DCiE
of 0,8.
=> That means, the lower the PUE or the higher
the DCiE the more power can be used for the IT
load and the more efficient the cooling of the
data-centre.May 2009Best Practice - Data Centre Cooling20New Design Trends for Air Conditioning Installations in Data CentresEnergy flow through the Data Centre
…so: Why energy efficient cooling?
Lighting 1%
100%Switchgear/Generator;
1%90%• Save operating cost
throughout the data centre's
lifetimeUPS 18%80%PDU 5%70%• Get more IT capacity out of
IT Equipment 30%60%your data centre at a given
available power by reducing
power use of secondary
physical infrastructure50%CRAC 9%40%Humidification 3%45 %
Air conditioning30%20%Chiller 33%10%0%
1May 2009Best Practice - Data Centre Cooling21New Design Trends for Air Conditioning Installations in Data Centres…so: Why energy efficient cooling?Source: Lawrence Berkeley National Lab; Data centre energy benchmark case studies
May 2009Best Practice - Data Centre Cooling22New Design Trends for Air Conditioning Installations in Data CentresRequirements of the IT-equipment
and the data-centreMay 2009Best Practice - Data Centre Cooling23New Design Trends for Air Conditioning Installations in Data CentresTarget of computer air conditioning:
Cold supply air in front of the rack
at any time of the year for trouble-free operation of the
IT-equipmentMay 2009Best Practice - Data Centre Cooling24New Design Trends for Air Conditioning Installations in Data CentresTarget of computer air conditioning:
Cold supply air in front of the rackSource: INTELSource: HPhorizontal air distribution through the rackMay 2009Best Practice - Data Centre Cooling25New Design Trends for Air Conditioning Installations in Data CentresServer
air inlet
temp. !!Source: ASHRAE
May 2009Best Practice - Data Centre Cooling26New Design Trends for Air Conditioning Installations in Data CentresThe updated ASHRAE recommended Environmental Envelope:Limits:•
•
•
•May 2009Best Practice - Data Centre CoolingMax. room temp.
Min. room temp.
Max. room hum.
Min. room hum.27°C
18°C
60%
25%27New Design Trends for Air Conditioning Installations in Data CentresEquipment requirements – Air conditions
return airHeat
load
QRecommendation for return air
26 °C ; 40 % r. H.Only reachable by ΔT of approx.
8Kand supply conditions:
18 °C ; ~ 80 % r. H.supply air
May 2009Best Practice - Data Centre Cooling28New Design Trends for Air Conditioning Installations in Data CentresEquipment requirements - Airflow
return airDesign air volumeQ
VL =
ρ A * cpA * ΔT
Heat
load
QVL =
Q =
ρA =
cpA =Air volume [m³/s]
Heat load [kW]
Density [kg/m³]
Specific heat capacity
of air [kJ/kgK]
ΔT = Difference between
discharge and supply
temperature [K]supply air
Reference value approx. 300 m³/h per kW
May 2009Best Practice - Data Centre Cooling29New Design Trends for Air Conditioning Installations in Data CentresEquipment requirements - Filtration
return air
Filtration of the circulated air is required.Heat
load
QEquipment has to be protected
against dust from outside air,
walls, ceiling and the raised floor.
Suggested: filter class
EU4 Mainfilter
EU5 or Pre-filter EU2,
EU5 Mainfiltersupply air
May 2009Best Practice - Data Centre Cooling30New Design Trends for Air Conditioning Installations in Data CentresEquipment requirements – Relative Humidity
The printed circuit boards (PCBs) have
to be protected against:
- Electrostatic discharge (ESD)
- Conductive anodic filament (CAF)
CAF is caused by too high humidity, the
relative humidity in the room therefore
should not exceed 60%
ESD is caused by too low humidity, the
relative humidity in the room therefore
should not be lower than 25%May 2009Best Practice - Data Centre Cooling31New Design Trends for Air Conditioning Installations in Data CentresElements influencing the
Data Centre Cooling efficiencyMay 2009Best Practice - Data Centre Cooling32New Design Trends for Air Conditioning Installations in Data CentresElements influencing the Data Centre Cooling Efficiency
Ambient Conditions (Location)
Free CoolingRoom TemperatureAir DistributionRoom HumidityRefrigerant Charge
Raised Floor HeightFilter StatusPerforated
Tile QuantityInstalled Options
Redundancy LevelPerforated Tile
Opening FactorPump Technology
Leakage
Airflow RatePipe Sizing
RefrigerantWater TemperaturesDimensions
Part Load Behaviour
Fan TechnologyHeat Exchanger SurfaceDrycooler Size
May 2009Filter SurfaceBest Practice - Data Centre Cooling33New Design Trends for Air Conditioning Installations in Data CentresElements influencing the Data Centre Cooling Efficiency
1. The room:•
•
•
•
•
•
•
•
•Air distribution
The raised floor
Raised floor height
Perforated tile quantity
Perforated tile opening factor
Airflow leakage rate
Pressure in the raised floor
Room temperature
Room humidityMay 20092. The CRAC-unit:•
•
•
•
•
•
•
•
•
•
•
•Return air temperature
Return air humidity
Water temperatures
Type of expansion valve
Heat exchanger surface
Part load behaviour
Filter surface / status
Fan technology
Unit dimensions
Refrigerant / refrigerant charge
Installed options
Standby-unit operationBest Practice - Data Centre Cooling34New Design Trends for Air Conditioning Installations in Data Centres1. The roomMay 2009Best Practice - Data Centre Cooling35New Design Trends for Air Conditioning Installations in Data Centres• Air distribution
<=
• The raised floor
• Raised floor height
• Perforated tile quantity
• Perforated tile opening factor
• Airflow leakage rate
• Pressure in the raised floor
• Room temperature
• Room humidityMay 2009Best Practice - Data Centre Cooling36New Design Trends for Air Conditioning Installations in Data CentresAir distribution
The parameters of the air circuit: Reduction of air side pressure drop
1
2External statical pressure3Installed equipment
„supply air“4Quantity open tiles5Air flow leakage rate6Air flow77Filter/Heat exchangerInstalled equipment
„return air“6
1
5431
May 2009to 72: reduction of air side pressure drop = reduction of fan power consumption
Best Practice - Data Centre Cooling37New Design Trends for Air Conditioning Installations in Data CentresAir distribution
1 to 7The parameters of the air circuit:
A pressure drop reduction of 10 Pa in the air circuit means:- 2 to 3% reduction of EC-fan power consumption
- 1 to 2% reduction of power consumption of a standard radial fanCaution: Reduction of air side pressure drop: Yes, but the raised floor
has to be pressurized. For an even air distribution in the raised floor an
overpressure of approximately 20Pa is needed. The open tiles have to
be balanced and a sufficient pressure has to be ensured.May 2009Best Practice - Data Centre Cooling38New Design Trends for Air Conditioning Installations in Data CentresAir distribution
Further parameters of the air circuit: Separation of cold and hot air28°C
8 Avoiding of bypasses
99 Rack-design8ΔΤ1010 Installed equipment18°C
Separation of cold and hot air = max. ΔΤ = max. energy efficiency!
May 2009Best Practice - Data Centre Cooling39New Design Trends for Air Conditioning Installations in Data CentresAir distribution
Air Cooling – A matter of a Defined Air PathHot/Cold Aisle
Concept• Cold supply air distribution only in the cold aisles
• Warm return air only in the hot aisles
• Open tiles only in the cold aisle
• Risk of mixing cold and hot air is high
May 2009Best Practice - Data Centre Cooling40New Design Trends for Air Conditioning Installations in Data CentresAir distribution
Air Cooling – A matter of a Defined Air PathDucted Return
Air Concept• Cold supply air distribution only in
the cold aisles
• Warm return air only in the hot
aisles into a false ceiling
• Open tiles only in the cold aisle
• Risk of mixing cold and hot air is
lower
May 2009Best Practice - Data Centre Cooling41New Design Trends for Air Conditioning Installations in Data CentresAir distribution
Air Cooling – A matter of a Defined Air PathDucted Supply and
Return Air Concept• Cold supply air into ducts fitted to the supply air side of the racks
• Warm return air through ducts fitted to the exhaust side of the racks
• Open tiles only in the area of supply air ducts
• No risk of mixing cold and hot air
May 2009Best Practice - Data Centre Cooling42New Design Trends for Air Conditioning Installations in Data CentresAir distribution
Air Cooling – A matter of a Defined Air PathCold Aisle
Containment• Cold supply air distribution only in the cold aisles
• The cold aisle is separated from the hot aisle
• Warm return air only in the hot aisles into a false ceiling
• Open tiles only in the cold aisle
• No risk of mixing cold and hot air
May 2009Best Practice - Data Centre Cooling43New Design Trends for Air Conditioning Installations in Data Centres• Air distribution
• The Raised floor
• Raised floor height
• Perforated tile quantity
• Perforated tile opening factor
• Airflow leakage rate
• Pressure in the raised floor
• Room temperature
• Room humidityMay 2009Best Practice - Data Centre Cooling<=
<=
<=
<=
<=
<=44New Design Trends for Air Conditioning Installations in Data CentresThe Raised Floor = Supply Air Duct !
Raised Floor void according to Room size and Load Density
Sufficient Pressure in order to deliver a equal air volume
pattern through the whole Room, cable sealing for power
and IT Cabling
Avoid Installation such as Pipes, Cable Trays etc.
Cable Management IT Cabling „from above“
especially for Rooms with limited Floor Void
Unused IT cable should be removed
Each barrier creates a pressure drop and results in higher energy consumption of the CRAC unitsMay 2009Best Practice - Data Centre Cooling45New Design Trends for Air Conditioning Installations in Data CentresRaised floor – unused cables should be removed…May 2009Best Practice - Data Centre Cooling46New Design Trends for Air Conditioning Installations in Data CentresRaised floor – For supply air (and cables/pipes)May 2009Best Practice - Data Centre Cooling47New Design Trends for Air Conditioning Installations in Data CentresLeakage Airflow - …to be avoided…May 2009Best Practice - Data Centre Cooling48New Design Trends for Air Conditioning Installations in Data CentresRaised floor height
Rule of thumb:
The higher, the better !
Tile number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15A certain obstacle free area is
required for a proper supply of
cold air to any area of the room !
May 2009Best Practice - Data Centre Cooling49New Design Trends for Air Conditioning Installations in Data CentresRaised floor pressureTile number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Only a raised floor with sufficient
height and perforated tiles
with limited openings allow an
even air distribution !!!Source: IBM
May 2009Best Practice - Data Centre Cooling50New Design Trends for Air Conditioning Installations in Data Centres• Air distribution
• The Raised floor
• Raised floor height
• Perforated tile quantity
• Perforated tile opening factor
• Airflow leakage rate
• Pressure in the raised floor
• Room temperature
<=
• Room humidity
<=May 2009Best Practice - Data Centre Cooling51New Design Trends for Air Conditioning Installations in Data CentresReturn Air temperature ≠ Room temperatureReturn Air
24°C
24°
I M P O R T A N T !!!
Return Air≠Room
21°C
21°
Depending on heat
load the return air temp.
is at least 2 - 3K higher
than room temperatureSupply AirMay 200916°C
16°Best Practice - Data Centre Cooling52New Design Trends for Air Conditioning Installations in Data CentresBlanking plates in the rack –
separation of cold and hot aisle in the rackSource: HP
informs:
How to Meet “24 by Forever”
Demands of Your Data CentrePrevent internal hot air recirculation by sealing the front of cabinets with blanking plates, including empty areas in
the equipment – mounting surface, between the mounting rails, and the edges of the cabinets (if necessary).
May 2009Best Practice - Data Centre Cooling53New Design Trends for Air Conditioning Installations in Data CentresPlanning vs. RealityMay 2009Best Practice - Data Centre Cooling54New Design Trends for Air Conditioning Installations in Data Centres2. The Close control unitMay 2009Best Practice - Data Centre Cooling55New Design Trends for Air Conditioning Installations in Data CentresDesign of the CRAC unit: Build in Energy Efficiency
Target:• Reduction of fan power
consumption• Reduction of compressor
power consumption
Main aspects:• Maximisation of heat
exchanger surface• Maximisation of filter
surface• Reduction of airside
pressure drop• Fan technology, reduction
of the fan speed
May 2009Best Practice - Data Centre Cooling56New Design Trends for Air Conditioning Installations in Data CentresEnergy and cost saving by reducing power consumptionMay 2009Best Practice - Data Centre Cooling57New Design Trends for Air Conditioning Installations in Data Centres2. The close-control-unit:• Fan technology
<=
• Part load behaviour
• Standby-unit operation
• Filter surface / status
• Heat exchanger surface
• Unit dimensions
• Return air temperature
• Return air humidity
• Water temperatures
• Type of expansion valve
• Refrigerant / refrigerant charge
• Installed optionsMay 2009Best Practice - Data Centre Cooling58New Design Trends for Air Conditioning Installations in Data CentresInfluence of the fan technology on the power consumptionCentrifugal fanvs.Example: CSD 431 A
• Air volume:EC-fan
Example: ASD 451 A13.000 m³/h• Air volume:13.000 m³/h• Total cooling cap.: 44,0 kW• Total cooling cap.: 43,9 kW• Fan power cons.:• Fan power cons.:3,9 kW2,3 kW• Reduction of fan power consumption by 42%
• Savings: 1.822,- €/year @ 0,13 €/kWh
May 2009Best Practice - Data Centre Cooling59New Design Trends for Air Conditioning Installations in Data CentresInfluence of the fan technology on the power consumption
…but, EC-technology is much more than efficiency…••Scalable air volume
setting via
Controller
on demand
Direct drive
technology, no belts+
+
+
+
+•
May 2009Low vibration
Best Practice - Data Centre Cooling+Easy adaption to changing
space conditions
Additional energy savings
Reduced noise levels
Long and maintenance-free
operation
No abrasion, No belt dust ,
No additional filtration neededQuiet running AC unit
60New Design Trends for Air Conditioning Installations in Data Centres2. The close-control-unit:• Fan technology
• Part load behaviour
<=
• Standby-unit operation
<=
• Filter surface / status
• Heat exchanger surface
• Unit dimensions
• Return air temperature
• Return air humidity
• Water temperatures
• Type of expansion valve
• Refrigerant / refrigerant charge
• Installed optionsMay 2009Best Practice - Data Centre Cooling61New Design Trends for Air Conditioning Installations in Data CentresInfluence of the fan technology on the power consumption
EC-fan part load behaviour100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
AirflowMay 2009Absorbed PowerBest Practice - Data Centre Cooling1/2
Airflow
1/8
Absorbed
PowerAirflowAbsorbed Power62New Design Trends for Air Conditioning Installations in Data CentresInfluence of the fan technology on the power consumption
EC-fan part load behaviour (CW-Standby-Management)
Sample:
4x ASD1900CW at 26°C/40%
Water 10/15°CAirflow: 3x 39.000 m³/h
Fan power = 3x 12,6 kW = 37,8 kW
Lpa,2m = 3x 71,6 dB(A) = 76,4 db(A)Standby3x 146,8 kW = 440,4 kW net sensibleAirflow: 4x 29.000 m³/h
Fan power = 4x 5,3 kW = 21,2 kW
Lpa,2m = 4x 50,8 dB(A) = 56,8 db(A)
4x 114,6 kW = 458,6 kW net sensible=> Energy savings:
16,6 kW x 8760h x 0,13 = 18.904 €/year @ 0,13 €/kWh
May 2009Best Practice - Data Centre Cooling63New Design Trends for Air Conditioning Installations in Data Centres2. The close-control-unit:• Fan technology
• Part load behaviour
• Standby-unit operation
• Filter surface / status
<=
• Heat exchanger surface
• Unit dimensions
• Return air temperature
• Return air humidity
• Water temperatures
• Type of expansion valve
• Refrigerant / refrigerant charge
• Installed optionsMay 2009Best Practice - Data Centre Cooling64New Design Trends for Air Conditioning Installations in Data CentresFilter surface / status
Anfangsdruckverlust
„Clean filter“,
"sauber"
pressure dropEnddruckverlust
„Dirty filter“,
"schmutzig"
pressure drop1
FiltermatteG4ZigZagFilterG4ZigZagFilterHPG480..85Pa2160..200Pa65..70Pa130..150Pa35..45Pa70..100Pa1„from a clean filter to a dirty filter“:Reduction of airflow at same fan power
consumption .
Too less airflow may lead to „hot spots“ in
the room ! Intelligent filtermanagement will
avoid this.2„from a small filter surface to a large filter surface“:Reduction of fan power consumption at
same airflow!May 2009Best Practice - Data Centre Cooling65New Design Trends for Air Conditioning Installations in Data CentresFilter surface / status
Filter Control Management
What does it mean?•Intelligent airflow control in case of dirty filter =>the fan speed will be adapted according to the
actual filter pressure drop•A required filter change will automatically be
indicatedBenefits:+ Protection against low airflow and hot spots
+ The airflow across the unit is constant at any time
+ Longer lifetime of the filter
May 2009Best Practice - Data Centre Cooling66New Design Trends for Air Conditioning Installations in Data Centres2. The CRAC-unit:• Fan technology
• Part load behaviour
• Standby-unit operation
• Filter surface / status
• Heat exchanger surface
<=
• Unit dimensions
<=
• Return air temperature
• Return air humidity
• Water temperatures
• Type of expansion valve
• Refrigerant / refrigerant charge
• Installed optionsMay 2009Best Practice - Data Centre Cooling67New Design Trends for Air Conditioning Installations in Data CentresUnit dimensions / Heat exchanger surfaceStandard ASD 612 A
Footprint:
Cooling capacity:
tot abs power:
Noise level:
COP:
51,0kW
EER:LowNoise/Energy ALD 612 A1,91 m²
61,3 kW
12,6 + 4,5 kW
60,4 dBA
4,87
3,58Footprint:
Cooling capacity:
tot abs power :
Noise level:
COP:
EER:
May 2009Footprint:
Cooling capacity:
tot abs power :
Noise level:
COP:
EER:+ 0,36 m²
+2,0 kW
- 1,9 kW
- 5,7 dBA
+ 0,23
+ 0,53Best Practice - Data Centre Cooling2,27 m²
63,3 kW
12,4 + 2,8 kW
54,7 dBA
5,10
4,11=> savings:
2.163 €/year
@ 0,13 €/kWh
68New Design Trends for Air Conditioning Installations in Data Centres2. The CRAC-unit:• Fan technology
• Part load behaviour
• Standby-unit operation
• Filter surface / status
• Heat exchanger surface
• Unit dimensions
• Return air temperature
<=
• Return air humidity
<=
• Water temperatures
• Type of expansion valve
• Refrigerant / refrigerant charge
• Installed optionsMay 2009Best Practice - Data Centre Cooling69New Design Trends for Air Conditioning Installations in Data CentresInfluence of the return air conditions
The leading and most important temperature
is the air entering the IT equipment (server).
According to the new ASHRAE environmental
envelope supply air temperatures up to 27°C
are possible. That would lead to return air
temperatures of approx. 37°C.35°C
35°8K27°C
27°May 2009Please note: A low return air set-point does
not „cure“ problems with heat load. It is the
other way around: The lower the return air setpoint the lower the usable cooling capacity of
the unit. Furthermore the operating costs are
increasing.High return air temperatures and lower return
air humidity do not change the content of
water in the room. The risk of ESD is as low.
Best Practice - Data Centre Cooling70New Design Trends for Air Conditioning Installations in Data CentresInfluence of the return air conditions
Advantages of high return air temperatures:
(1) CW-units: High return air temperatures are leading towards higher
water temperatures. The starting temperature of the free-cooling is
much higher.
(2) CW-units: To get the same cooling capacity with high return air
temperatures and high water temperatures the airflow of the unit can
be reduced. Lower airflow leads to lower fan power consumption and
a lower noise level.
(3) DX-units: Higher return air temperatures are leading towards higher
evaporating pressure. With constant condensing pressure the delta
between evaporating and condensation pressure is reduced. The
compressor power consumption is decreasing. Furthermore the fan
speed also can be reduced.
But please be aware that too high evaporating pressure can damage
the compressor.
May 2009Best Practice - Data Centre Cooling71New Design Trends for Air Conditioning Installations in Data CentresThank you for you attention !May 2009Best Practice - Data Centre Cooling72