APW President BICSI-MAIT Sept09 Rev1

7/28/2019 APW President BICSI-MAIT Sept09 Rev1

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Datacenter 'Last Mile' Challenges

- A Rack Perspective

S.Venkatraman

10 th September09


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Power Management

ThermalManagement

Level 1

Securitymanagement Cable

ManagementEnvironmentMonitoring

Spacemanagement

Thermal planning &Consultancy

Services - CFD

ThermalManagement

Level 2

DATA CENTER LAST MILE RACK PERSPECTIVE


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Thermal Management & Planning

Cooling /Air flow in the Data Center


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Thermal&

Vapour Barrier

Q1

Q1

Q1 Q1Q2C1

R1 R2 R3

R1, R2, R3 Racks

Q1 Outside Heat

C1 PAC Cooling

C1 = Q1 + Q2

THERMAL EQUILIBRIUM

Eliminate Q1 using thermal & vapour barrier to save on Opex


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THERMAL EQUILIBRIUM


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THERMAL MANAGEMENT - BASICS

Q = M Cp T

T = (T l - Te ) Q = 1.08 x cfm x T

Limitations

Precision AC T across evaporator coil cannot

exceed 10C (std products)

Better heat removal

By improving air flow

Effective utilization of cold air

Key factor Air quantity & Distribution

Te Tl


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THERMAL MANAGEMENT - BASICS


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LETS BIFURCATE THE PROBLEM

Low & medium density cooling Focus on Air flow management

High density cooling

Focus on using chilled water as themedium of cooling


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AIR FLOW MANAGEMENT

Under floor air management

Above floor air management (includingabove the false ceiling)


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THE P ROBLEM : Subfloor Air Velocity Air Handlers generate a great deal of air velocity in

the subfloor, causing a reduction in static pressure,which results in low-flowing and negative-flowing tiles.

In many cases, simply adding additional Air Handlers

creates more velocity, causing more hot spots tooccur.

As additional or hotter-running equipment is added to

the room, the hot spots spread and cause the entireroom to run warmer

The Goal - Slow down the subfloor velocity, therebyincreasing static pressure


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CURRENT SITUATION

This typically requires a lower air handler temperature set pointand/or additional air handlers to keep the equipment cool, which

requires increasing the energy consumption being used.


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DID YOU KNOW The average data center has 2x the number of Air

Handlers actually needed to cool the equipment

Approximately 60% of all cool air produced by Air Handlers never actually hits the heat load (Servers,Hubs, Routers, Switches, etc)

ASHRAE (American Society of Heating, Refrigerationand Air- Conditioning Engineers), is encouraging datacenter managers to raise the temperature set points tolower energy costs

95% of all data centers are paying a large energypenalty caused by poor subfloor air distribution


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Eliminate hot spots

Direct more cool air to the heat load

Completely balance your subfloor air

Allow you to raise the temperature set pointson your air handlers

Reduce your energy costs from 23% - 42%

WHY SUBFLOOR AIR MANAGEMENT


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Below-Floor CFDs show us howthe air flows from the Computer Room Air Conditioner (CRAC)through the subfloor plenum upinto the ambient room.

STEP ONE A Below-Floor CFD AnalysisIncludes Before and After: CFM Readings

Cable Cutout Leakage Lowest/Highest Flowing Tiles Velocity/Vector/Pressure Readings Deliverable

Before

After


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STEP TWO Air Balancers

By balancing the subfloor pressure,

we manage it and can properly deliver air to the heat load.

Air balancers are strategically placed,using our intellectual properties, toenhance and balance static pressure

RESULTS FROM INSTALLED Air Balancers

Every perforated tile within the data

center will produce a significantlyhigher plume of air.

Each perforated tile will providegreater cooling.

Helps eliminate hot spots Increased air stratification


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STEP THREE

Eliminate Bypass

Airflow

Air Plumes Before FlowLogix

Air Plumes After FlowLogix

Between 100 600 CFM is leakedthrough a cable cutout opening; thiscauses loss of CFM and a decrease instatic pressure

The mixing of hot and cold air increases energy consumption.


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With Riser AddedThe performance of that same 30-tonunit with improved air stratificationand a return air temperature of 31C

the unit will put out more than 30tons.

At the higher return air temperatures,the Air Handler capacity is increasedand the chiller plant operates moreefficiently.

Increase Return Air Temperature

A 30 ton nominal, down-flow, chilledwater Air Handler might have a sensible

capacity of 27 tons when operated at22C but only 23 tons when operated at20C. Eighteen percent more capacity atthe higher operating temperature! Froma cost viewpoint, it might be possible toeliminate one in five Air Handlers.

Please view ASHRAE TC9.9 & ambient conditions

STEP FOUR


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Based on CFD analysis and corrective actionthereof

Average reduction in data center energy costs rangingfrom 23% - 42%

Drops of cold aisle temperature ranging from 3 11degrees

Elimination of hot spots

Increased static pressure in the subfloor

Moving 95% +/- of available conditioned air delivered to

the heat load

RESULTS


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AIR FLOW MANAGEMENT

Under floor air management

Above floor air management (includingabove the false ceiling)


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DATA CENTER - AIRFLOW ISSUES Over 60% of cooling energy is wasted in the form of

bypass air

Re-circulated air from IT equipment exhaust canreduce server performance

Air stratification forces set points of precision coolingequipment to be lower than recommended

Air remixing drives down precision cooling efficiencies

Most data centers produce significantly more

cold air then is required by the IT devices


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DC COOLING ISSUE DEFINITIONS Bypass Airflow

Air supplied from precision air conditioning units

that bypasses the rack-mounted equipment

Recirculation

Exhaust air from rack-mounted devices that makesits way back to the device inlets

Air Temperature Stratification Layer effect of temperature gradients from the

bottom to the top of the enclosure


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BYPASS AIRFLOW A comprehensive study

performed by Upsite

Technologies Inc. concludedthat 60% of the air suppliedin traditional data centers iswasted due to bypassairflow

Significant efficiencies andcost savings can be realizedby eliminating bypassairflow.


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RECIRCULATION Hot air exhaust circulating

back into its own intake cancause device thermaloverload.

Typical manufacturer inlettemperature threshold for

device operations is 35C.

Exceeding manufacturersoperating device thresholdcan lead to unplanned

computing system outagesand data loss.


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TEMPERATURE STRATIFICATION

Significant gradient of air temperatures beyond ASHRAE TC9.9 placesdevices at risk of thermaloverload

Maintaining inlettemperature gradients

within the ASHRAErecommended rangesignificantly saves energy


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TEMPERATURE BOUNDARIES ASHRAE Technical Committee 9.9 has provided a standard as a

statement of reliability

Manufacturers specification is an allowable range within which theproducts can run effectively

ASHRAE TC9.9Manufacturer Specification

Device InletTemperature

Range (64.4 - 80.6)F (50 - 95)F


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HCS optimizes the use of existingprecision cooling capacity within thedata center to deliver effective cooling

to IT loads- Balance cool air supply with demand

HCS is a scalable, flexible and provendesign that can be adapted to existinginfrastructures as capacity demandsincrease- No stranded supplemental cooling

assets

HEAT CONTAINMENT SYSTEM


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FLEXIBILITY AND HCS CHIMNEY The HCS chimney allows both

active and passive ducting options

Using the passive solution willreduce energy usage when theserver exhaust within theenclosure is substantial.

However, for enclosures withpotential backflow, active hotswappable fans can mediate therisk of thermal overload


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BACKFLOW AND STAGNATION Low density racks with passive

chimneys can be susceptible tobackflow

Backflow can lead to hightemperature air leaking throughundesirable regions of theenclosure

Backflow increases pressurebuildup which may lead to server exhaust fan stagnation andultimately damage to computingequipment


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MODELED RESULTS - 3D View Traditional

Data Center containing all airflow issues


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MODELED RESULTS - 3D View HCS Data

Center optimized results of full containment


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COLD AISLE CONTAINMENT


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BEFORE & AFTER COLD AISLE CONTAINMENT

27 oc 21 oc

16o

c

27 oc 17 oc

16oc


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ARCHITECTURAL VIEWWarm return air

Cold supply air Cold supply air

Warm return air


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COLD AISLE CONTAINMENT - Schematic


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WHAT IS THE BENEFIT OF CONTAINMENT All energy used to move or produce cool air is used to cool IT equipment

IT equipment will only receive conditioned air, maintaining ideal operating

environment leading to better performance

Air conditioner set points can be tuned to deliver ideal inlet air temp to ITequipment and eliminate the energy from overcooling

Warm air is sent directly back to conditioning systems increasing overallcooling performance

Predictable air management is obtained

Yields a savings greater than 30% reduction in the energyconsumed in a typical legacy datacenter CRAC cooling

system


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DATA CENTER FLEXIBILITY VS.

COOLING PERFORMANCE Demand for Flexibi lity

Ability to support any Vendor IT Rack of any depth or height Ability to support any density anywhere on the white space

Available Rack space unencumbered by cooling equipment in the rackrows

Adds, Moves and change happens everyday

Demand for cooling Performance Efficient cooling systems cost less to operate Optimized designs that match cooling capacity and demand cost less to

purchase Predictable performance in a dynamic environment drives reliability

Cooling Performance and Flexibility can co-exist


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LEGACY DATACENTER COOLING STYLE


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SOLUTION: CREATE COLD AND HOT AISLE


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COMMON MISTAKES

Enclosure without Blanking PanelEnclosure without BlankingPanel and common outlet for Hot and Cold Air through Top

Mounted Fan

DONT DONT


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NO INSULATION BETWEEN TWO ENCLOSURES

HOT AIR /COLD AIR MIXESBETWEEN TWOENCLOSURES

INSULATED SIDE PANELS

WRONG WAY RIGHT WAY


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IN SUMMARY Focus on air flow for addressing thermal issues in DC

Follow air containment options for enhancingperformance of existing & upcoming DC

Thermal planning using Computational FluidDynamics (CFD) & deploy corrective actions and do aperiodic audit Energy saving proposition


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HIGH DENSITY COOLING Water has 3500 times higher density than air

Cooling using water has become common incritical spaces and the traditional beliefs are beingbroken by use of appropriate technology

50%+ energy saving with major space savings withuse of chilled water based cooling for the DC


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Front of Enclosure

Rear of Enclosure

How Does It Work? Rear Door Heat Exchanger replaces existing rear door of IT enclosure Rear door has chilled water Supply & Return quick connections at bottom or top Chilled water circulates through fin+tube coil from Supply connection Equipment exhaust air passes through coil and is cooled before re-entering the

room Heat is rejected from room through Return water connection

Tube + FinHeat exchanger


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Chilled Water Cooling System Rear door provides 100% sensible cooling No condensation, no need for reheat or humidification Chilled water distributor creates a fully isolated, temperature controlled

Secondary Loop Chilled water source - city water, building chilled water, packaged chiller

~65o

F

~45 oF


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Thermal Image - Before & After


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IN SUMMARY

For higher density racks use chilled water

cooling solution


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"You can manage what you canmonitor"

RACK ENVIRONMENT MONITORING


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IN SUMMARY What is measured is managed

Monitor environment parameters for correctiveaction & resource optimization


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CONCLUSION Proper Air flow management below and above false

floor for effective cooling & hence optimization of energy & resources for low & medium density DCs

Plan thermal management through audit & simulationusing CFD techniques

Use Chilled water based system for high densitycooling requirement in DCs

Monitor environment parameters for corrective action& resource optimization


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S.VenkatramanVP Sales

APW President Systems LimitedMob: 09324235923Email: [email protected]

APW President BICSI-MAIT Sept09 Rev1

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