Introducing the Heat Wheel to the Data Center

Robert (Dr. Bob) Sullivan, Ph.D.Data Center Infrastructure Specialist

KyotoCooling International

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A New “Free Cooling” Technique

• New ASHRAE Environmental Guidelines• Introducing the Heat Wheel (KyotoCooling)• Efficiency Comparisons

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Computer ProductEnvironmental Limits - New

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Computer ProductEnvironmental Limits - New

• Who developed the new limits– Not ASHRAE– Computer Manufacturers

• Temperature Ranges– Recommended– Allowable– Prolonged Exposure

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Computer ProductEnvironmental Limits - New

• Benefits– Larger environmental envelope– Wider temperature ranges – to 27 °C (81 °F)– Change from Relative Humidity to Dew Point

• Range from 5.5 °C (42 °F) to 15 °C (59 °F)– Greater opportunity for “Free Cooling”

• Concerns– Low Rh levels at low Dew Point and high temperatures– Latent Cooling with cold coil systems and Dew Points

above 10 °C (50 °F)

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Free Cooling Techniques

• Airside Economizing – “Free Air Cooling”

• Waterside Economizing – Chilled water without the refrigeration

• Heat Wheel – the new player in the business– Airside Economizing without air transfer

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Free Cooling TechniquesHeat Wheel Application

• Uses a heat wheel to transfer the heat from the computer room outside environment

• Normal heat wheel (energy recovery system) application is in building HVAC systems– Pre-Cools the air in Summer– Pre-Heats the air in Winter

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Typical Heat Wheel Application

• Cooling in Summer • Heating in Winter

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Heat Wheel – Data Center Cooling Heat Wheel – Data Center Cooling

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Heat Wheel Application

• Heat wheel applied to a computer room cooling system

• “Plumbed Wrong”– Wheel actually isolates computer room and

ambient air

• Isolated Hot Aisle • Room flooded with cold air

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Heat Wheel Cooling - IllustrationHeat Wheel Cooling - Illustration

04/19/2304/19/23 1111

Heated datacenter air is collected above the datacenter ceiling

Physical separation of hot and cold air

Heatwheel

‘Cold ‘ outside air

Exhaust air

Cold make up air in front of the IT equipment

Heated air flows through the heatwheel and is cooled down to a temperature of 18-27°C (adjustable)

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Heat Wheel Application

• Little exchange of air from ambient to computer room– Air exchange through wheel <0.3%– Can be eliminated with use of computer room air– Conditioned outside air sufficient to maintain

positive pressure in computer room introduced through building AHU

• Minimizes exposures of airside economizing– Contamination – Humidity Control

• Airside economizing without the air transfer

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Heat Wheel Application

• Minimal Water usage required

• Supplemental cooling – Modular DX units located within each cell– Chilled water supplied from central plant

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Capitol Cost of Installation

• Capitol cost equivalent to conventional chilled water installation

• KPN estimate for 12.5 MW critical load in the Netherlands– 80M Euro, apporx. $130M– Includes – Building, Electrical, Mechanical,

Controls, etc.– Doesn’t include – Land, Computer Equipment,

Cabling, Move In costs

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Heat Wheel Application Control mechanism

®

Recirculation Recirculation of heated of heated outside airoutside air Increase Increase

rotation rotation speed of the speed of the

wheelwheelIncrease of Increase of outside air outside air

volumevolume Additional Additional cooling with cooling with

DX cooling DX cooling capacitycapacity

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Heat Wheel ApplicationControl Mechanism

• Computer Room airflow volume controlled automatically by:– Delta T across wheel – Power dissipated by computer equipment

• Supply air temperature to computer room is controlled by: – Rotation speed of wheel – Ambient temperature – Airflow volume through wheel on ambient side

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Heat Wheel ApplicationControl Mechanism

• Cold temperatures - below 9 °C (48 °F)– Warm ambient exhaust air recircirculated back to input

face of the wheel– Wheel speed and ambient airflow volume at minimum

levels

• Normal temperatures - 10 °C (50 °F) to 23 °C (95 °F)– Wheel speed increased– Ambient airflow increased

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Heat Wheel ApplicationControl Mechanism

• Warm air temperatures - above 23 °C (76 °F)– Heat Wheel combined with supplemental DX or Chilled

water cooling– Supplemental cooling brought on in stages, keeping heat

wheel at maximum capacity

• Hot temperatures – above 35 °C (95 °F)– Wheel stops– All cooling with supplemental cooling– Computer room fans circulate air through evaporator coil – Ambient fans dissipate heat from DX condenser coil

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Heat Wheel ApplicationControl Mechanism

• Safety Net - If supplemental cooling fails– Computer room can be maintained at ambient

temperature + 2 °C – Just using the Heat Wheel and ambient airflow– Temperature of room will not “run away”

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Heat Wheel Application600 kW Capacity

• Maximum wheel size available : 6000mm• Computer room supply air temperature: 25°C• Specific ∆t over ICT equipment : 12°C• Inside recirculation per hour : 150.000 m3

• Maximum wheel rotation : 3 RPM• Capacity of cooling : 600 kW• Ambient temperature : 15°C• Mechanical Load : 48 kW• Mechanical PUE : 0.08

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Summary of Heat Wheel Cooling Application

• Novel application of a proven technology• Components readily available for immediate

construction• Requires new construction or major

renovation• Minimal complexity, requires little

maintenance and skill level of facilities technicians

• Both energy and environmentally efficient

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Summary of Heat Wheel Application

• Limitations and Concerns with Heat Wheel Cooling System– New to data processing industry

• Reluctance to be the first to implement

– Requires unique architectural configuration• Cooling cell immediately adjacent to computer room• Hot Aisle containment • Cold air flooding

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Energy Efficiency Calculations

• Mech Eff = Mechanical Energy Critical Load

– A lower ME value indicates more efficient operation

• The EER-A (Annualized Energy Efficiency Ratio) or Coefficient of Performance (COP)– EER-A = Annual Energy (Critical Load)

Annual Mechanical Energy – The annual energy usage of the systems being cooled

(Critical Load) divided by the annual mechanical energy usage

– A higher EER-A value indicates more efficient operation

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Comparison of Cooling TechniquesME = Mechanical Load / Critical Load

Cooling Type Hot & Dry

Cold & Dry

Marine Hot & Damp

Refrigeration Process (Baseline)

0.60 0.60 0.60 0.60

Baseline with Airside Economizing

0.22 0.15 0.15 0.23

Baseline with Water Free Cooling

0.23 0.23 0.23 0.26

Heat Wheel – Single Cell 0.22 0.08 0.10 0.17Redundant Cooling withHeat Wheel- 4 + 1 Cells

0.14 0.05 0.07 0.11

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Comparison of Cooling TechniquesAnnualized Energy Efficiency Ratio

Cooling Type Hot & Dry

Cold & Dry

Marine

Hot & SDamp

Refrigeration Process (Baseline)

1.67 1.67 1.67 1.67

Baseline with Airside Economizing

4.55 6.67 6.67 4.35

Baseline with Water Free Cooling

4.35 4.35 4.35 3.85

Heat Wheel - Single Cell 4.55 12.50 10.00 8.29

Heat Wheel – 4 + 1 Cells 7.14 20.00 14.30 9.09

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Conventional technical infrastructureConventional technical infrastructure

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KyotoCooling infrastructureKyotoCooling infrastructure

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Infrastructure you do NOT need anymoreInfrastructure you do NOT need anymore

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Modular Heat Wheel Cooling Modular Heat Wheel Cooling

04/19/2304/19/23 2929

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Modular Heat Wheel Cooling Modular Heat Wheel Cooling

04/19/2304/19/23 3030

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Roof Mounted Package Units

• old PUE old PUE 2,95 (400 kW) 2,95 (400 kW)• new PUE new PUE 1,15 (1200 kW) 1,15 (1200 kW)• Annual energy savings with 400 kW > € Annual energy savings with 400 kW > €

630.000 (measured and calculated by ECN)630.000 (measured and calculated by ECN)

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KyotoCooling Efficiencies

KyotoCooling EfficienciesSupply=25C Delta

T=12C

Location

Annual PUEm

+25% PUEm

100% Kyoto Mixed

100% DX

           

SanFrancisco 0.095 0..188 95.3% 4.6% 0.0%

Sacvramento 0.124 0.155 79.9% 18.2% 1.9%

San Joxe 0.106 0.133 86.7% 12.1% 0.2%

Seattle 0.090 0.122 94.7% 5.3% 0.0%

KyotoCooling EfficienciesSupply=22C Delta

T=12C

Location

Annual PUEm

+25% PUEm

100% Kyoto Mixed

100% DX

           

SanFrancisco 0.107 0.134 88.6% 11.1% 0.2%

Sacvramento 0.140 0175 72.1% 23.1% 4.8%

San Joxe 0.122 0153 78.7% 20.4% 0.9%

Seattle 0.099 0.124 89.9% 9.9% 0.2%

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KyotoCooling Efficiencies

KyotoCooling Efficiencies Supply=25C Delta T=20C

Location

Annual PUEm

+25% PUEm

100% Kyoto Mixed

100% DX

           

SanFrancisco 0.042 0.052 88.6% 11.4% 0.0%

Sacvramento 0066 0082 72.1% 27.8% 0.1%

San Joxe 0.0.51 0.0.64 78.7% 21.3% 0.00%

Seattle 0.039 0.049 89.9% 10.1% 0.0%

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KyotoCooling Efficiencies

Efficiency Improvements over chilled water system with Mech Efficiency of 0.6

Per MW of Critical Load

Supply Temperature = 25 C Delta T = 12C

Location ChW Energy

+25% Mech Efficiency Energy

Mech System Improve

Overall Improve

Savings/MW@0.10 / kWHr

  kW kW      

SanFrancisco 600 118 80% 30% $422,000

Sacvramento 600 155 74% 28% $398,000

San Joxe 600 133 78% 29% $409,000

Seattle 600 112 81% 30% $427,000

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More High Density Cooling InformationMore High Density Cooling Information

• Robert (Dr. Bob) Sullivan, Ph.D.– dr-bob@ix.netcom.com– 408-776-8873

• KyotoCooling International, BV– Mees Lodder

• mlodder@kyotocooling.com• +31 6 2394 6557

– www.kyotocooling.com