Engineered Systems - April 2008 - (Page 38)

This Time, Water Cooled Was All Wet 8" D IA . 1" D IA . T 6" D IA . 6" D IA . (T Y P ) U P -P -010 6" D IA . T NO NO M M U P -C H -007 NC U P -C H -008 U P -D C -005 NC U P -D C -006 U P -D C -007 C H E M IC A L S H O T FE EDER AND C O R R O S IO N C O U P O N S T A T IO N M M 8" D IA . U P -P -009 C H IL L E R BY PASS V A LV E (T Y P ) 8" D IA . (T Y P ) 8" D IA . C H IL L E R B Y P A S S W IT H IS O L A T IO N V A L V E (T Y P ) 8" D IA . 1" D IA . T 1" D IA . 8" D IA . 1" D R A IN TO Y AR D D R A IN (T Y P ) 8" D IA . 3/4" D IA . 6" D IA . T P -30.006 6" D IA . 8" D IA . V A L V E D B L IN D F LA N G E F O R E M E R G E N C Y C H IL LE R C O N N E C T IO N A N D F IL L (T Y P ) 1" D R A IN W IT H H O S E C O N N . (T Y P ) P -30.005 T O F LO O R D R A IN M M NO NC M M NO NC 8" D IA . 8" D IA . D R Y C O O LE R S U B LO O P B Y P A S S V A LV E (T Y P ) F R O M LO O P R E L IE F V A L V E S E T A T 100 P S IG 3/4" D IA . T O G L Y C O L R E S E R V O IR . 1 1/4" D IA . F R O M G L Y C O L M A K E -U P S Y S TE M. F R O M LO O P M 8" D IA . U P -A S -002 8" D IA . 8" D IA . 6" D IA . B Y P A S S 3/4" D IA . NO BY PASS C O NTR O L V A L V E (T Y P ) M M 3/4" D IA . NO D R A IN W IT H HO SE CO NN. P R E S S U R E G A U G E (T Y P ) 1. F O R S Y M B O L S , A B B R E V IA T IO N S A N D N O T E S S E E D R A W IN G S M -001 A N D M -002. 2. T H IS D R A W IN G IS F O R G E N E R A L S Y S T E M C O N F IG U R A T IO N O N L Y . A L L S P E C IA L T IE S A R E N O T S H O W N . F O R S P E C IF IC S Y S T E M D E V IC E S S E E D E T A IL E D P L A N S , D E T A IL S A N D S P E C IF IC A T IO N S . 3. P U M P S , E X P A N S IO N T A N K S , A IR S E P A R A T O R S , C H E M IC A L P O T F E E D E R S A N D A S S O C IA T E D H Y D R O N IC S P E C IA L T IE S A R E IN C L U D E D IN P A C K A G E D H Y D R O N IC P U M P IN G S Y S T E M P A C K A G E S A N D W IL L B E P R O V ID E D U N D E R A S E P A R A T E C O N T R A C T . T H E IN S T A L L IN G C O N T R A C T O R S H A L L C O O R D IN A T E W IT H JA C O B S R E G A R D IN G A S S IG N M E N T A N D IN S T A L L A T IO N O F T H E S E S Y S T E M S . 4. T H E A IR C O O L E D C H IL L E R S A N D D R Y C O O L E R S W IL L B E P R O V ID E D U N D E R A S E P A R A T E C O N T R A C T . T H E IN S T A L L IN G C O N T R A C T O R S H A L L C O O R D IN A T E W IT H JA C O B S R E G A R D IN G A S S IG N M E N T A N D IN S T A L L A T IO N O F T H E S E U N IT S . 5. D IF F E R E N T IA L P R E S S U R E S E N S O R S F O R C O N T R O L O F L C W S Y S T E M P U M P S S H A L L B E L O C A T E D A T U P -A H U -002, U P -A H U -006, U P -A H U -201, A N D U P -D O A S -201. U P -E T -004 M A N U A L A IR V E N T (T Y P ) A N T I-T H E R M O S Y P H O N LO O P 12" M IN IM U M D R O P 3/4" D IA . G E NE R AL NO TE S M U P -E T -005 D R A IN W IT H HO SE CO NN. T O LO O P M T O LO O P FIGURE 1. Variable primary chilled water plant with dry cooler economizer. Nature. But there it is. Another one of those kiss your sister kind of words: compromise. When we emerged from our little conclave, those who had not witnessed our genius simply scoffed at the proposed notion. Many saw the compromise as simply a short cut to a predisposed conclusion. A settling, if you will, as in settling for second best. The consequence of which is not very satisfying just ask my lovely bride. So upon being challenged, I naturally did what any designer with conviction would do: I folded like a cheap tent at the end of a rainy Boy Scout Jamboree. That is to say, I backed down quickly. But the concept engineer didn’t. His gut told him that this was the answer and he would be delighted to allow me to disprove the idea. A life-cycle cost analysis (LCCA) was commissioned by the owner and I was asked to compare the air cooled and water cooled options. When cornered, I uttered the aforementioned pronouncement. Specifically, I stated with confidence that while the air cooled option had merit on the water conservation front, there was no way it could win a head-to-head LCCA shoot out. Unbeknownst to me at the time, was that at that precise moment I had placed an advance order for a healthy serving of crow. DATA CENTER ENVIRONMENTAL OPTIMIZATION In a concerted effort to optimize the HVAC design while maintaining an appropriate data center environment, the environmental conditions were reviewed. Per the Design Conditions for Datacom Equipment Centers design guide from the ASHRAE Datacom Series, the recommended cold aisle (rack inlet) conditions for a Class 1 data center are as listed in the first two columns of Table 1. After polling the owner’s operations personnel (a varied lot, I might add), the consensus was to use the criteria listed in the third column of Table 1. It is worth noting that the table reflects the more relevant rack entering conditions, not the more commonly assumed (and frankly useless), average space conditions. Based on a nominal 70° supply air temperature at the rack and an airside differential of 25°, the hot aisle temperature would be about 95°. While this is well within the design guide parameters and equipment tolerances (it’s not called the hot aisle for nothing), it presented a massive shift in expectations on the part of the endusers. A shift, however, was warranted since this change in the RFA environmental parameters created a cascading effect that ultimately carried back to the condensing mediums. Specifically, higher air temperatures allow higher chilled water temperatures, which increase chiller 38 En gi neer ed S y stem s April 2008

Table of Contents Feed for the Digital Edition of Engineered Systems - April 2008

Engineered Systems - April 2008 Contents Editor’s Note Back2Basics HVAC Challenge Case In Point Commissioning Building Automation Energy Wiz HVACR Designer Tips This Time, Water Cooled Was All Wet Cleanroom Design In 10 Easy Steps It's Not The Heat, It's The Humidity Issues & Events Computers and Software Products Glossary Classifieds Advertiser Index Tomorrow’s Engineer

Engineered Systems - April 2008

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