EXPERIMENTATION OFEXPERIMENTATION OF LIQUID COOLING FORLIQUID COOLING FOR MOBILE BASE STATION

S. Le Masson, D Nörteshäuser, Orange Labs FranceT. Galkin, J. Huttunen, T. Volkov, O. Amper NOKIA Finland

3rd ETSI EE Workshop Sofia AntipolisJune 3-5, 2015

Outline

1 – Introduction

2 State of the art2 – State of the art

3 – Liquid cooling Lab tests

4 – Experimental measurements on real Base station

5 – Conclusions & Perspectives

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Introduction : OPERA-Net 2 general information Eureka-Celtic European project with partial funding from France and Finland Project duration: 36 months with 6 months extension until May 31st, 2015 Coordination by OrangeGoal : reduction of environmental impact of mobile radio

t knetwork 11 Partners (operator, industry, academia):France:

Finland :

Belgium :

UK:

website: http://projects celticplus eu/opera-net2/website: http://projects.celticplus.eu/opera net2/

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INTRODUCTIONM bil t k t th 20% f ti Mobile network represents more than 20% of power consumption Services are growing (broadband, more services…) Telecom equipment power is also growing… Heat management becomes more and more important in order to remainHeat management becomes more and more important in order to remain

compliant with climatic standards Telecom shelters and outdoor cabinets are widely used in mobile Network

Need to optimize the thermal conception of telecom shelters and outdoor cabinets Politic of sustainable development of Orange

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2- State of the art (1/2) Example with telecom shelter Example with telecom shelter Air conditioning (split system)

– Advantage– Fine Thermal control

Di d t– Disadvantage – Electrical consumption– Maintenance

Forced Ventilation– Advantage

– Simple – Disadvantage g

– No thermal regulation– Limited by the low thermal inertia of the shelter– Low heat capacity– Dust / Filtration

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2- State of the art (2/2)I ti l ti Li id Innovative solutions

PCM Solutions (liquid solid)– Need regeneration

Liquid

Need regeneration– Expensive

Thermosiphon loop – Works are in progress

Solid– Works are in progress– Interesting results

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3- Liquid cooling lab testsC ld Pl t R k l l Cold Plates => Rack level Internal heat exchanger

Rear door heat exchanger => Subrack level

Heat exchanger

Rear door heat exchanger => Subrack level

7Liquid loop

3- Liquid cooling lab tests

Liquid cooling at component level Liquid cooling at component level – Nokia Flexi Radio module modified – Aluminum prototype is made by

machiningChannels are closed by glue and– Channels are closed by glue and screws

– Channels are optimized by CFD for Power Amp area (3 sub channels)

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3- Liquid cooling lab tests water flow rate is stabilized at

0.04kg/s

Temperature measurements at component levelcomponent level Case 1 = Int Amb temp = 15°C Case 2 = Int Amb Temp = 35°C Case 3 = Int Amb Temp = 50°C

Results show no direct correlation between internal Temp & Amb Temp

Liquid cooled BS could be Liquid cooled BS could be installed in any temperature conditions

pPUE = 1.07 (Only cooling)

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3- Liquid cooling lab tests

Effect of water flow rate Effect of water flow rate

Effect is quite linear with low temperature variation For flow rate x 3 : temperature are reduced only of 3-5°C Optimization of water flow rate could be done Optimization of water flow rate could be done

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4 Experimental measurements on real Base station Presentation of experimental sitep

– Shelter divided in 2 parts – Air cooled part

– Nokia Flexi BS 2500W – Radio loads (loads simulations) ( )– cooled by Fan (variable speed)

– Liquid cooled part– Nokia Flexi BS 2500W – Radio loads (loads simulations) Radio( )– cooled by water loop

Air cooled

Air inletRadio loads

Door 2.5m

equipment

Internal insulated

2.22m

Fan Air outlet

DoorWater cooled

equipment

1.74m

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4,20mWater to air heat exchangerRadio

loads

4 Experimental measurements on real Base stationNokia Flexi Base StationVentilation

Shelter

Liquid cooling zone

Pump

air outlet

Shelter

Air cooling zone

External heatexchanger

Pump

air inlet

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4 Experimental measurements on real Base stationAir cooled side

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4 Experimental measurements on real Base station

Mean Temp Air Liquid DifferencePAx 63.7 36.0 ‐27.7

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RFx 60.0 50.0 ‐10.0

4 Experimental measurements on real Base station

Air cooled zone – cooling power consumption = 310 Wcooling power consumption 310 W

Liquid cooled zone – Pump + HEX fan power consumption = 34W– Pump + HEX fan power consumption = 34W

Energy balance on liquid loop – Thermal measurements (outside)

It i ibl t ( 80%) li id l– It is possible to reuse energy ( 80%) on liquid loop

– More precise measures will be done

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5- Conclusion & Perspectives Experimental water cooling tests have been done

– Without issue regarding water leakage

Cooling at component level gives better resultsCooling at component level gives better results– Heat is remove closer to hot components– Cooling energy consumption is divide by 10 – Water cooling gives solution in order to reuse heat lost– LCLC – Lower noise

Perspectives Experimentation will continue

– 1 year – Improvements will be done (Thermal insulation for liquid loop)– Optimizations of External Heat Exchanger (over sized for present experiment)Optimizations of External Heat Exchanger (over sized for present experiment)– Added specific Heat Exchanger to remove rectifier heat dissipation– Reliability and availability estimations (MTBF will be better with lower Temp)– Economical studies – New designs at Room / building levele des g s at oo / bu d g e e

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thank youy

This work was partially funded by the French and Finnish Public AuthoritiesThis work was partially funded by the French and Finnish Public Authorities

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