Powering the Software Defined Network

Free Cooling: A Complete Solution on Reducing Total Energy Consumption for

Telecommunication Base Stations

Ehsan B. Haghighi

ehsanbh1@gmail.comThermal Designer

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Contents

• Introduction

• Free Cooling

• Energy and Controlling Model

• System Components and Operation

• Single and Dual Zone Strategies

• Case Studies and Results

• Conclusion

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Introduction

• Cooling traditionally counted for 25-50% of the total energy consumption in a typical base station.

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Free Cooling

Extracting fresh air into the shelter

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Source: https://www.dantherm.com/

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Facebook data centre in Luleå, Sweden

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Energy Model

INFSOLENVITCOOL QQQQQ

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Controlling Model

if TSET <= TO+ΔTlag=> Air Conditioning if TSET > TO+ΔTlag => Free Cooling

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System Components

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System Operation

Free cooling Air conditioning

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Single and Dual Zone Strategies

Single zone strategy Dual zone strategy

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Case Studies• A typical BTS with L=4 m, W=3 m, and H=2.8 m• QIT = 4 kW and QBattery = 0.4 kW (on average)• UEnv = 1 W/m2K and UBattery = 0.5 W/m2K• ΔTlag = 2 °C• Tset = 25 °C for the single zone strategy • Tset = 25 °C (battery compartment) and Tset = 35 °C (IT/electronic) for

the dual zone strategy• COP = 2.5 and idle fan power consumption for the main air

conditioning system are assumed to 100 W• The power consumption for the free cooling unit is assumed to be

80 W on average• In the dual zone strategy a small air conditioning unit with COP of

2.4 and 75% running time is used to provide the required cooling load for the smaller zone

• The area for the smaller zone is assumed to be 10% of the area of the main zone

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Locations

• Copenhagen (Denmark), San Francisco (USA), Shanghai (China) and Dubai (UAE)• Weather data: ASHRAE handbook

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Copenhagen, Denmark

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San Francisco, USA

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Shanghai, China

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Dubai, UAE

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Results

Cooling System Size (kW)

AC FC

Copenhagen, Denmark 5.0 4.9

San Francisco, USA 4.9 4.9

Shanghai, China 5.5 4.9

Dubai, UAE 6.0 4.8

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Copenhagen, Denmark

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San Francisco, USA

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Shanghai, China

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Dubai, UAE

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Results

Savings (%)

Single Zone Dual Zone

Copenhagen, Denmark

91 85

San Francisco, USA 94 86

Shanghai, China 53 85

Dubai, UAE 21 68

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Conclusion

• Free cooling is a well-proven method to reduce total energy consumption in a typical BTS

• Free cooling can be used in either single or dual zone strategies

• In hot and warm climate zones dual zone strategy is recommended