session title: demystifying efficiency in the data center utilizing airflow as a system

Session Title:Demystifying Efficiency in the Data Center

Utilizing Airflow as a System

Presented By:Jon deRidder

Enabled Energy

Learning Objectives:

• Identify how to improve your Power Usage Effectiveness immediately

• Design an efficient airflow system in a data center and apply to your own facilities

• Measure and verify the savings achieved in efficient data centers

• Identify ASHRAE TC 9.9 and its effect on the ecosystem of the data center

BackgroundDefining the terms:• Data center

– The room (regardless of size, age, how anyone “feels” about it, the budget that you have [or had] to build or maintain it, or how reliable it is / is not) that houses your computing equipment.

BackgroundDefining the terms:• Data center• Computing equipment

– Server, network, or storage devices that compute, transport, and store information (data).

BackgroundDefining the terms:• Data center• Computing equipment• PUE

– Power Usage Effectiveness. Taking the total facility power (feeding your data center) and dividing by your IT load (UPS load will get you close) will give you your PUE. This PUE number will be greater than 1 (hopefully less than 3) and provides a “uniform” way of calculating how much power is going to your IT load vs. how much power you are consuming to accomplish your compute (the “tax”). A PUE of 2 is typical in a “legacy center”, while a PUE of 1.5 is “typical” for a new data center build (many are now becoming very aggressive i.e. 1.1 and 1.2).

Courtesy of a very sad data center experience

Air Movement16%

Electricity Trans-former/ UPS

13%

Lighting, etc.4%

Cooling33%

IT Equipment33%

PUE = 3.0

BackgroundDefining the terms:• Data center• Computing equipment• PUE• A tax

– Something you pay because you are forced to or because you are not aware of it.

BackgroundDefining the terms:• Data center• Computing equipment• PUE• A tax• ASHRAE TC 9.9

– The American Society of Heating, Refrigeration, and Air Conditioning Engineers Technical Committee 9.9 brought together many hardware manufacturers, locked them in a room, and came up with the latest “Thermal Guidelines for Data Centers”. This is a GUIDELINE NOT A STANDARD.

– Your equipment warrantee is provided by your equipment manufacturer and ultimately this is who gets to decide if you are or are not “compliant” with housing the equipment in a “proper environment”. Examples: power quality; temperature and humidity controls; particulate type; and size.

– In the end data wins…he or she with the most information is likely going to be the person who controls how, when, who, where, and why.

BackgroundDefining the terms:• Data center• Computing equipment• PUE• A tax• ASHRAE TC 9.9• Reliability

– The resulting investment of many painstaking strategy sessions (brain cells) coupled with lots of redundant components (which translates to big dollars) allowing for the concurrent maintainability of your entire infrastructure (planned maintenance to avoid system downtime).

– Hope is not a strategy!

BackgroundDefining the terms:• Data center• Computing equipment• PUE• A tax• ASHRAE TC 9.9• Reliability• Efficiency

– An aggressive pursuit (and an exhausting effort after achieving the appropriate levels of redundancy) to achieve maximum throughput with minimal restriction and waste.

– This starts with doing the best you can with what you have, but working intently and diligently to make it better.– Please note that reliability is and must be first.– Walnuts can be opened with steamrollers, but they don’t need to be and the result isn’t pretty.

BackgroundDefining the terms:• Data center• Computing equipment• PUE• A tax• ASHRAE TC 9.9• Reliability• Efficiency• Problem

– Opportunity

Self Actualization

Esteem

Social

Safety

Physiological

BackgroundDefining the terms:• Data center• Computing equipment• PUE• A tax• ASHRAE TC 9.9• Reliability• Efficiency• Problem

– Opportunity

Optimization

Efficiency

Reliability

Strategy

Communication

Airflow - A Systems Approach

Cause: Meaningful metrics are needed for the data center.Effect: PUE and CUE are now metrics the industry is accepting as “standard” and yet

these are not universally understood or defined.

Cause: Delivery systems were developed around outdated guidelines.Effect: Dramatic overcooling of IT equipment!

ASHRAE TC 9.9 published new thermal guideline for data centers(~78.6˚F at the intake of compute equipment).

Cause: Airflow delivery systems are generally unbalanced and full of air-mixing opportunities.

Effect: Typical delivery systems have >50% “bypass” airflow.

Airflow - A Systems ApproachIt all starts with

Organization Distribution

It falls apart with Poor communication Bad strategy

DiscoverYour PUE• Calculate how much you are spending now on the system and each part that creates the

total.

Your CRAC/CRAH efficiency• Start with the intake temperature of your server, network & storage equipment.• Then calculate the efficiency of your CRAC/CRAH units

– (CFM * delta temperature) * .9 = BTUs of accomplished cooling.

The path for your airflow• Supply path

– Supply panels– Aisle layout (hot/cold)– Opportunity for recirculation

• Return path– What is the path of least resistance?

Most Valuable Investment (MVI)

Source: UpSite

Bypass Airflow

Backward-curved blades use blades that curve against the direction of the fan wheel's rotation. The blades are single thickness with 9 to 16 blades inclined away from the direction of rotation. Air leaves the impeller at a velocity less than its tip speed. Relatively deep blades provide efficient expansion with the blade passages. The backward curvature mimics that of an airfoil cross section and provides good operating efficiency with relatively economical construction techniques. Backward-curved fans are much more energy efficient than forward curved fans. The EC Fan design moves the air in more of a straight line.

Forward-curved blades use blades that curve in the direction of the fan wheel's rotation. It has 24 to 64 shallow blades with both the heel and tip curved forward. Air leaves the impeller at velocities greater than the impeller tip speed. Tip speed and primary energy transferred to the air is the result of high impeller velocities and operating most efficiently at lowest speed.

Forward Curved Fan EC Fan

17”

Reduced AIR

FLOWAREAS

Under-Floor Baffle

Proportional Distribution Tiles

Sealing Cable Cutouts

Blanking Openings in Cabinets

Containment

Ducting CRACs to Drop-Ceiling Air Space

Optimized

Thank You!

7X24 Fall Meeting Airflow secrets revealed

Tom WeissPresident C2

October 23, 2012

Presentation goals

Provide baseline for analyzing effective airflow cooling in a data center

Provide financial measurements for airflow efficiency

Share common problems and their source Provide information on effective CFD Answer questions regarding airflow

Let’s start with the science

Air cooling is a method of dissipating Heat!

It works by making the object to be cooled have a larger surface area or an increased flow of air over its surface; or

both!

Problems with some raised floor cooling!

Advice from Eaton

“As much as 30 to 60 percent of the data center utility bill goes to support cooling systems. If that figure seems too high, it is.”

“Poor airflow management reduces both the efficiency and capacity of computer room cooling equipment.”

An easy fix?

…. “optimize the existing cooling system through mechanical and room layout changes, using relatively inexpensive devices to redirect and concentrate available airflow”.

What can we fix? Cold Aisle / Hot Aisle Containment Curtains, blanking panels Close the holes in the floor

We still haven’t determined what happens to the air once it leaves the floor.

So how does the cold aisle really work?

CFM vs.Usable CFM

Traditional Measurements CFM – Cubic Feet Per Minute Static Pressure and open space

Performance questions How much air are we wasting? How does the air flow out of the tile?Do we need more air or do we need to be more

efficient with the air we have?

How should it work?

The three components of cold aisle airflow efficiency:

Cool the upper servers Flow to the serversCome out of every section of the tile

No back flow into the floor!

Stratification heat!

Industry white paper

Tile mixing!

Air is like water!

Bypass the servers Entrainment Pollute the return air Room mixing

Stratification

Short cycle / Jet stream

950 CFM - Venturi

Wasted air = wasted energy + hot spots

“Only 28% of the air, in a traditional raised floor system, cools the servers (72% does not cool)”

“2.6 times more cooling than is necessary and yet we still have hot spots”

Lower set points More CRAC units Higher energy costData from Uptime Institute Dr. Bob F. Sullivan and

Kenneth G. Brill – “24 by Forever”

How expensive?

Cooling costs are 50% of the total bill!

“Data center managers can save 4 percent in energy costs for every degree of upward

change in the set point, according to Mark Monroe, the Director of Sustainable Computing

at Sun Microsystems (JAVA)”

Data Center costs

OPEX – Energy cost 40%!Asset refresh costs –

Server failure 20% higher!CAPEX– Crac units, more devices!PUE – 2.0 or higher!

What is going on?

CEETHERM / NSF study

Measure relationship of airflow to rack inlet Analyze air at the particle level Analyze CFD models Provide feedback to the industry

Tile/Rack Level Air Flow Modeling

05/04/2012

54

Fan speed setting dial

Perforated floor tiles with dampers

42 U

1.98m.(6'-6")

10 U

10 U

10 U

10 U

0.53m.1'-9"

0.44m.1'-5 1/2"

0.44m.1'-5 1/2"

0.44m.1'-5 1/2"

0.44m.1'-5 1/2"

0.09m.3 1/2"

Server Simulator

55 Rack and Tile Geometry

3030=900 pores, 0.5”0.5”, Porosity=39%

49=36 pores, 1.25”5.25”, Porosity=41%

88

2084

56

Dampers

Tile top

Rack

Pressure Outlet

Pressure Inlet

TileGrill

Fan

Mass Flow Inlet

Symmetry

4million cells

Details of Tile geometry

Details of Rack Geometry57

24inch

Mass flow inlet

Symmetry

Pressure inlet (K=10)

Tile top

Pressure outlet

Front View (aisle)

Aisle

Plenum

Dampers

Symmetry

Pressure inlet

24inch

1ft

Mass flow inlet

Symmetry

Tile top

Pressure outlet

Server Simulator

1

Grill

18inch

18inch

18inch

18inch

Server Simulator

2

Server Simulator

3

Server Simulato

r 4

Wall

Wall

Wall

Wall

Wall

Plenum

Aisle

5inch

Side View

Fan

Fan

Fan

Fan

12inch

1inch Dampers

1.5inch9.25inch

Front View (fan)

fan

hub

6inch3inch

9inch

wall

Front View (grill)

wall

open area

0.5inch

1inch

18inch

• Fan: Target mass flow rate boundary condition

Current CFD Models for Tile Flows

Uniform Velocity

Uniform Velocity

Tile (F)

P

High Pressure

Low Pressure

Vin

• Porous jump model [1]

• Body force model [2] As mass is conserved hence momentum is under

accounted:

Momentum source term specified just above the tile:

mass flow velocity through pores

velocity in porous jump

model

∆𝑀=𝜌 𝐴𝑡𝑖𝑙𝑒𝑉 𝑖𝑛×(𝑉 𝑖𝑛

𝐹 −𝑉 𝑖𝑛)

Uniform Velocity

Velocity Profile

Sx

X

58

[1] Patankar, S. V., Airflow and Cooling in a Data Center, Journal of Heat Transfer, 2010, Vol. 132, pp. 073001-1-17.[2] Abdelmaksoud, W. A., Khalifa, H. E., Dang T. Q., Elhadidi, B., Schmidt, R. R., Iyengar, M., Experimental and Computational Study of Perforated Floor Tile in Data Centers, Intersociety Conference on Thermal Phenomena (ITHERM), Jun 2-5, 2010, Las Vegas, USA.

Rack Flow = 2594 CFMTile Flow = 0 CFM

(0% of Rack Flow)

[ref] Kumar, P., Joshi, Y., Experimental Investigations on the Effect of Perforated Tile Air Jet Velocity on Server Air Distribution in a High Density Data Center, Intersociety Conference on Thermal Phenomena (ITHERM), Jun 2-5, 2010, Las Vegas, USA.

PIV CFD

Tile Flow = 0% of Rack Flow

Tile

Aisle top

Rac

k

Ais

le c

ente

r

Velocity (m/s) Tile

Aisle top

Rac

k

Ais

le c

ente

r


(~20% of Rack Flow)



PIV CFD

Tile

Aisle top

Rac

k

Ais

le c

ente

r

Velocity (m/s)

Tile

Aisle top

Rac

k

Ais

le c

ente

r


(~60% of Rack Flow)


PIV CFD


Tile

Aisle top

Rac

k

Ais

le c

ente

r

Tile

Aisle top

Rac

k

Ais

le c

ente

r


(100% of Rack Flow)



Tile

Aisle top

Rac

k

Ais

le c

ente

r

Tile

Aisle top

Rac

k

Ais

le c

ente

r

PIV CFD


(100% of Rack Flow)



Porous Jump Model

Body Force Model

Resolving Tile

Geometry

PIVTile

Aisle top

Rac

k

Ais

le c

ente

r

Tile

Aisle top

Rac

k

Ais

le c

ente

rTile

Aisle top

Rac

k

Ais

le c

ente

r

Tile

Aisle top

Rac

k

Ais

le c

ente

r

Let’s end with the science

Air cooling is a method of dissipating Heat!

Object to be cooled have a larger surface area – Freeze the room = $

Or an increased flow of air over its surface – Flow to the servers = higher set point savings!

Or both – Flow of cool, non – polluted air, through the rack!

Questions?

Thank you!

<Insert Picture Here>

RMDC Cooling System Adjustments

Kevin DonnellyBuilding Engineer

69

Example of TitleExtending to Two Lines

• First Level Bullet– Second level bullet

• Third level bullet– Fourth level bullet

• Fifth level bullet

70

<Insert Picture Here>

Program Agenda Example

• Our Understanding of XYZ• Capabilities and Value Drivers• Benefits & Assessments• Oracle Solutions• Oracle Credentials• Appendix

71

Appendix<Insert Picture Here>

72

Temperature and Humidity Adjustment Results

• Invested $31K for installation of plenum return ductwork.• Server inlet temperature reduced from 80 to 70 degrees• Number of CRAC units humidifying from 11 to 1• Mechanical cooling energy reduced 155 KW (24%)• Annual energy savings of $53K• Payback 7 months

75

Other Adjustments

• Seal air gaps (Koldlok)• CRAC temperature setpoint 72 to 76 degrees• Condenser water loop setpoint 75 to 65

degrees

79

Questions?

session title: demystifying efficiency in the data center utilizing airflow as a system

Documents

data centerbackgrounddefining

new data center

data centerthe room

store information data

end data winshe

legacy center

equipment warrantee

equipment manufacturer