Evaporative Cooling of Data Centers. Why is this important? What does the industry say? How does the...

Evaporative Cooling of Data Centers


Why is this important? What does the industry say? How does the technology work? How does it address the problem? What do we offer? What are the alternatives? If you are not already doing this work where

do you find it?



Data Center Knowledge July, 2010 survey of 240 readers

26% operate more than 10 data centers 63% are expanding Top five interest areas

Data Center Design Green IT and Energy Efficiency Power and Cooling Data Center Management and Automation Solutions to Reduce Energy Cost


Pike Research study Results released in August

$41B market by 2015 28% of all data center projects 46% of investments focused on reducing power

and cooling requirements


42U rack 84 blades 250w/blade 19.32kw/rack 50 racks 1Mw of server demand Plus…1Mw of heat rejection

= 275 tons of cooling and 100,000 to 150,000 cfm

2Mw total demand



Convert expense to revenue


“PUE” Previous slide PUE approximately 2.77 Target PUE approximately 1.0




Microsoft’s latest promos



What is Direct Evaporative Cooling Cooling occurs because water changes

phase from a liquid to a vapor Water vapor is introduced directly into air

stream Constant wet bulb temp Saturation efficiency 80% DB & WB approach


How much cooling can be achieved? Wet bulb depression

Difference between 100 DB and 70 WB System efficiency (aka “saturation efficiency”) of

80% 100-70 = 30 30 x 0.8 = 24 100-24 = 76


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PSYCHROMETRIC CHARTSea LevelBAROMETRIC PRESSURE 29.921 inches of Mercury

Linric Company Psychrometric Chart, www.linric.com

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Cooling Effect Sensible cooling = 1.08 * cfm * delta-t 1.08 * 10,000 * 24 = 259,200 btuh or 21.6 tons


What is Indirect Evaporative cooling Water never enters the supply air stream Indirect up to 75% system efficiency Straight sensible cooling Reduces wet bulb temperature


How much cooling can be achieved? Wet bulb depression

Difference between 100 DB and 70 WB System efficiency of 75% 100-70 = 30 30 x 0.75 = 22.5 100-22.5 = 77.5


Cooling Effect Sensible cooling = 1.08 * cfm * delta-t 1.08 * 10,000 * 22.5 = 243,000 btuh or 20.25

tons


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What is Indirect/Direct Evaporative cooling Consider it a two-stage hybrid First stage lowers dry bulb and wet bulb Second stage further lowers the dry bulb using

the first stage results as the starting point


How much cooling can be achieved (Stage One)? Wet bulb depression

Difference between 100 DB and 70 WB System efficiency of 75% 100-70 = 30 30 x 0.75 = 22.5 100-22.5 = 77.5


How much cooling can be achieved (Stage Two)? Wet bulb depression

Difference between 77.5 DB and 63.5 WB System efficiency of 80% 77.5-63.5 = 14 14 x 0.8 = 11.2 77.5-11.2 = 66.3

Total temperature drop is 22.5 + 11.2 = 33.7 degrees


Cooling Effect Sensible cooling = 1.08 * cfm * delta-t 1.08 * 10,000 * 33.7 = 363,960 btuh or 30.33

tons


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Cooling Effect Summary Direct evap

Supply temp = 76 degrees Tonnage = 21.6

Indirect evap Supply temp = 77.5 degrees Tonnage = 20.25

Indirect/Direct evap Supply temp = 66.3 Tonnage = 30.33


DALLAS

WICHITA

SACRAMENTO


How does this address the problem? Remember the goal…shifting the kw required

for cooling over to the kw available for servers Evaporative cooling vs. chilled water vs. DX


How does this address the problem? Aztec ASC ~ .25 kw/ton Air cooled rooftop ~ 1.15 kw/ton (10.5 EER)

Evaporative cooled chiller ~ .88 kw/ton


How does this address the problem? For our 30 ton example unit:

Aztec ASC ~ 7.5 kw Air cooled rooftop ~ 34.5 kw Evaporative cooled chiller ~ 26.4 kw


Potential applications Enterprise data centers Colocation data centers R&D labs Telecommunication equipment centers Server closets Container-based server centers Abandoned “big box” conversions


Applications that probably will not work Tropical environments Marine environments

Potential corrosion due to salt air Heavily polluted environments

Potential corrosion due to VOCs and ozone “Traditional” design criteria is specified


Issues to consider Hot aisle/Cold aisle separation Using the “worst case” scenario for design Be aware of the resulting dew point Remember the vapor barrier


Equipment characteristics to consider Control the water

All welded floor of stainless steel or aluminum All welded drain pans at least 4” high Internal velocities Mist eliminators Conduit for electrical and control wiring


Equipment characteristics to consider Know the water

Consider water quality Evaluate the use of automatic systems

Remember the end user


Aztec ASC line Indirect or indirect/direct evap Cooling-only or Cooling-

Heating systems DDC controls with Internet

access available Stainless steel evap sections Fully welded floor pans Fiberdek UL900cl2 media Duradek edge coating Cleanable media pre-filters Internal seismic rated

fan/motor isolation VFD capable Automatic fill and drain system DHTD “digital high turndown”

burner heating technology 1,500 – 37,500 cfm range


Alton HECD line Stainless steel evap sections Fully welded floor Fiberdek UL900cl2 media

optional Duradek edge coating optional Cleanable media pre-filters Automatic fill and drain system 5,000 – 64,000 cfm range


What are the alternatives? In-rack In-room Conventional HVAC Hybrid DX or Chilled

Water/Evaporative HVAC


What are the alternatives? In-rack


What are the alternatives? In-room


What are the alternatives? Conventional HVAC


What are the alternatives? Hybrid Dx or chilled

water/Evaporative Cooling


How to find the work Talk to electric utility folks Talk to local economic development folks Emphasize revenue vs. expense Emphasize easier repurposing of

abandoned retail space


Summary Direct evaporative cooling is the least

expensive Indirect/direct evaporative cooling is the most

effective The goal is to convert expense to revenue for

the client And remember….computers don’t sweat…so

go as warm as you can

Q & A


Date post:	26-Mar-2015
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