Data center free cooling use of heat wheel tech

BRUNS-PAK
Data Center Design/Build Solutions

Data Center Cooling
The use of “Heat Wheel” Technology

June 5, 2012

Data Center w/Advanced Heat Wheel
Technology Deployed
 In 2011, BRUNS-PAK deployed a state of the art data
center for a global Fortune 100 company utilizing
advanced Heat Wheel technology as a major source of
„free cooling‟.

 Project Details:
Greenfield site Located in Northwest US Projected
Tier IV Data Center & Infrastructure
mechanical
efficiencies
180,000 FT2 Bldg Phase 1/55,000 FT2 Raised Floor
PUEm = 1.15
4,050 kW UPS Phase 1 /10,800 kW Ultimate (2N)
10MW Generation Phase 1 /24MW Ultimate (2N)

Website: www.bruns-pak.com

Data Center w/Advanced Heat Wheel
Technology Deployed
The buildings energy conservation features include:
 Heat wheel technology that provides approximately 7,450 hours of
free cooling and 1,280 hours of partial free cooling.

 Rooftop HVAC units provide outside partial and full free cooling when
outside conditions permit.

 Water cooled compressorized CRAC units are equipped with free
cooling coils to provide free cooling when outside conditions permit.

 Lighting system controlled by either the card access system or by
motion sensors.

 Trees and plants indigenous to the area that eliminate the need for
an irrigation system.


What is a “Heat Wheel”?

 A “Heat Wheel” also known as a rotary air-to-air
energy exchanger, or rotary enthalpy wheel is a
revolving cylinder filled with an air-permeable medium
usually made of a non-corrosive, aluminum,
honeycomb material having a large internal surface
area.

Source: ASHRAE


How does a “Heat Wheel” work?

 Adjacent supply and exhaust airstreams each flow
through half the exchanger typically in a counter-flow
pattern to recover heat only (sensible) or total heat
(sensible plus latent).

Source: ASHRAE


Traditional use of “Heat Wheels”

 Used for decades in ventilation air-conditioning
systems

SOURCE: Illustration courtesy of XETEX


Benefits of Traditional “Heat Wheels”

 “Pre-warm” outside air utilizing indoor conditioned air
to reduce heating energy.
 “Pre-cool” outside air utilizing indoor conditioned air to
reduce cooling energy.
 Reducing heating and cooling energy allows the ability
to increase ventilation rates and improve overall indoor
air quality, if desired.
 Removes outdoor airstream moisture in the summer.
Note: Additional moisture removal through alternate source likely
required.
 Adds some moisture to outdoor airstream in the winter.
Note: Additional moisture through alternate source likely required.


Example of Traditional “Heat Wheel”
Performance - Summer

Exhaust Air (EA) Return Air (RA)
(89F DB, 73F WB) (75F DB, 63F WB)

Outside Air (OA) Supply Air (SA)
(95F DB, 78F WB) (81F DB, 68F WB)

Enthalpy Wheel

Outside air is directly supplied into the space and is “pre-
cooled” by the return air which is directly exhausted.


Example of Traditional “Heat Wheel”
Performance - Winter

Exhaust Air (EA) Return Air (RA)
(27F DB, 20F WB) (72F DB, 54F WB)

Outside Air (OA) Supply Air (SA)
(7F DB, 6F WB) (53F DB, 40F WB)

Enthalpy Wheel
Outside air is directly supplied into the space and is “pre-
warmed” by the return air which is directly exhausted.


“Heat Wheel” Technology in Data
Centers
 The same principles of traditional “Heat Wheel”
technology are applied, except:
 Sensible only “Heat Wheel” is utilized.
 “Heat Wheel” is arranged with the outside and
inside airstreams separated.

Source: Illustration courtesy of Kyoto Cooling


Benefits of “Heat Wheel” Technology in
Data Centers
 More efficient means of “free cooling” than direct
airside and waterside economizing.
 Separated airstreams minimize contaminates and
humidity exposure associated with direct outside air
systems.
 Minimizes make-up water consumption and water
treatment associated with evaporative cooling
systems.
 Potential reduction in overall building footprint.
 Cooling demand can be supplemented with 100%
air-cooled/DX during extreme climate conditions,
eliminating the need for a conventional chilled water
system. Note: air-cooled/DX circuit is integral to unit.

Data Centers
2008 Version
Low End Inlet 64.4° F DB
Temperature
High End Inlet 80.6° F DB
Temperature
Low End Moisture 41.9° F Dew Point

High End Moisture 60° RH & 59° F Dew Point

ASHRAE Standards developed in conjunction with IT hardware manufacturers.

ASHRAE TC 9.9 Standard allows more hours of “free-
cooling” regardless of the technology used.


Data Centers

Bin Data (8760 hrs) for New York City with a supply air
temperature set point of 73F DB and a return air
temperature of 95F DB:

 6526 hours of 100% “free cooling”.
 2198 hours of partial “free cooling” (i.e. simultaneous
“heat wheel” and supplemental mechanical cooling
operation).
 36 hours of 100% mechanical cooling.

Source: Data courtesy of Kyoto Cooling


Example of Sensible “Heat Wheel”
Performance

Exhaust Air (EA) Outside Air (OA)
(68F DB, 55F WB)
(88F DB, 63F WB)

Return Air (RA) Supply Air (SA)
(95F DB, 67F WB) (73F DB, 59F WB)

Sensible Wheel
73F (SA) - 68F (OA) = 5F Approach to achieve 100% “free cooling”
Outside and inside airstreams are separated. Recirculated return
and supply air is “pre-cooled” or “cooled” by the outside air, then
directly exhausted to atmosphere.

Projected Mechanical Efficiencies
PUEm = Mechanical Load
IT Load

Cooling Type Hot & Dry Cold & Dry Marine Hot & Damp

Refrigeration Process
(baseline) .60 .60 .60 .60

Baseline with direct
airside economizing .22 .15 .15 .23

Baseline with water-
free cooling .23 .23 .23 .26

Heat Wheel – Single
Cell .22 .08 .10 .17

Source: Data courtesy of Uptime Institute


Projected Mechanical Efficiencies
PUEm = Critical Load + Mechanical Load
Critical Load


“Heat Wheel” Technology Applied in
Data Centers

Some means of “hot-aisle” containment is recommended.


Data Centers

900kW roof-mounted Heat Wheel unit


Data Centers

900kW roof-mounted Heat Wheel units


NICHOLAS SAPIA
Senior Mechanical Engineer: BRUNS-PAK

Years of Experience: 20
PROFESSIONAL EXPERIENCE
Areas of Specialization:
Evaluating of existing facilities Mr. Sapia has twenty years of experience in data center
through coordination of
design requirements for projects. His experience ranges from evaluation of existing
highly technical projects,
redundancy concepts
facilities through coordination of design requirements for
highly technical projects. Mr. Sapia’s vast knowledge of
Education:
A.A.S. Mechanical mechanical concepts makes him a valuable asset in
Engineering Technology
B.S. Mechanical Engineering, interpreting mission critical facility needs and alternatives.
Train Air Conditioning, Air
Conditioning & Air
Distribution

Professional Membership:
ASHRAE
National Fire Protection
Association


Data center free cooling use of heat wheel tech

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