by Munte Sali and Robet Toze Data Cente Ai Manageent Meti-Patial Aoa Pea te only ting gowing ate tan enegy ue in data ente i new eti and aony to eaue and ontol te. One way to onide te oble o data ente enegy ue i to view te data ente a a giant ai u. In a eet wold, evey CFM o ai odued by te CRAC unit would ind it way to te eve inlet. Unotunately te wold i not eet. Ti ake ai-anageent eti a oweul tool o ioving te enegy eiieny o data ente. By quantiying ailow eoane, aility exeutive an eaue and quantiy te eetivene o tei data ente ooling yte o ange tat tey ake to tei ooling yte to ineae ai ooling eiieny. Ti aoa alie to bot taditional aied loo deign and non-aied loo aionditioning deign o data ente Ti atile eent ean to quantiy ai low eoane o bot taditional aied loo deign and non-aied loo ai-onditioning deign o data ente. Meti ae develoed tat will eadily eit owne, enginee and oeato to eaue and quantiy te eetivene o tei data ente ooling yte o ange tat tey ake to tei ooling yte to ineae ai ooling eiieny. Ti atile ooe novel data ente ai-anageent eti tat aat o eiulation, alo adde negative eue low, bya low and balane o eve and CRAC unit low. Te eti ae atial and ile to aly and ovide a eii aateiti o ea data all. Tee eti etabli ow well te ooled ai o te CRAC unit eae te eve inlet. Ideally, all o te ai o te CRAC unit would go to te eve. Wit tee eti, aility exeutive an eate a itue owing ow a o te ideal a data ente i, and ue tat itue to iove ai anageent. Fo tee eti, te ain aaete ae ai a low ate and teeatue, wi ae ued to exe te quantity and quality o enegy ulied to te eve. Tee ai anageent eti ae baed olely on te onideation o enible load. Fo ti onetual odel, te ollowing low ate ae onideed. CRAC low: Total ai-low ate odued by all oeating CRAC unit in te data ente i noally geate tan tat equied by te eve, due to at load oeation o IT and ouniation equient, and edundant CRAC unit tat ae ket oeational. Bya ailow: Ai tat leave te loo gille and etun dietly to te CRAC unit witout ooling eve. Re-iulation ailow: Ai diaged o eve tat etun and ixe wit illed ai enteing te eve. Tee ae indiated in Figue 1-4: T T CRAC Negative eue low M Mn Mb M M T M T Bya low M Seve T T Reiulation low Figue 1: Data ente ai tea
Figue 2: Reiulation ai low Figue 3: Bya ai low Figue 4: Negative eue low Teeatue a ound in tyial legay data ente ae ued: T 21 C, etun ai teeatue to CRAC (at CRAC), noally te CRAC etun ai et oint T 14 C, diage ai teeatue o CRAC (at CRAC) T 14.1 C, loo void teeatue (ate oo ai i dawn in), vey loe to T T 21 C, eve inlet ai teeatue (ixtue o gille and e-iulation ai) T 28 C, eve outlet ai teeatue (beoe old ai ixe wit it) Uing tee a low ate and teeatue, te ollowing a (3 node) and eat balane equation an be witten.
Ma equation: + n + b + Heat equation: Q ( T T ) Q Q Q ( T T ) ( T T ) ( T T ) Fo tee equation, te ollowing data ente ai anageent eti ae deived. Negative eue atio: NP n T T T T Bya atio: BP b T T T T Re-iulation atio: R T T T T Balane atio: T T BAL T T Te elationi between Negative Peue, Bya Peue, Reiulation and Balane, Ratio Uing te onet o equivalent balane between te loo low (CRAC low lu negative eue low) to eve low, te ollowing exeion i deived: BAL ( 1+ NP) I tee a low ate ae exeed in te o bya and e-iulation a low ate, and wit ute deivation give: 1 R BAL( 1+ NP) 1 BP Ti elationi i eeented in Figue 5. 1.00 B(1+NP) R 0.75 0.50 0.25 0.25 0.5 0.75 1 1.33 2 4 0.00 0 0.25 0.5 0.75 1 BP Figue 5: Data ente ai anageent eti
Ti ga dilay oon value o eiulated and bya ailow atio o dieent ai-anageent tategie. Te line on te ga eeent te balane between ai ulied by te CRAC and ai equied by te eve. (Te nube in te box to te igt o te ga ae te value o te line.) Te ink line at te to o te ga oeond to a balane o 0.25, wi ean eve ae not getting enoug old ai, wile te blue line on te a igt oeond to a value o 4, wi ean te CRAC ae oduing ou tie oe ai low tan te eve equie. Te ule line in te iddle ean uiient ailow. Fo value above te ule line, tee i not enoug ai going to te eve; wile below te ule line, te ooite oble exit too u ailow. Balane ow te atio o ai o te CRAC unit tat eae te eve inlet. Te ideal balane i 1, owing tat all te ai o te CRAC unit i going to te eve inlet. Te ale o tee atio i zeo to 1. Fo bya and eiulation, te ideal eult would be zeo tat i, no bya ai and no eiulation. On te ote and, i te bya atio i 1 (BP1), all o te CRAC ooling ai would be byaed, wit no ai available o eve. And iilaly, i eiulation i 1 (R1), all eve ai would be e-iulated, wit no ooling ai enteing o te CRAC unit. Patial Aliation Even i it i diiult to eiely eaue NP, BP, R and BAL, tee i alway a eal eii value tat i aateiti o evey data ente. Negative eue low i noally vey low and diiult to eaue, oweve, it ould be eetively odelled and eoted uing CFD (outational luid dynai). In atial te, te CRAC yte ould be ontolled baed on uly ai and not on etun ai. Unotunately, ew data ente ae oeated tat way. Contolling on uly ai iove te unioity in eve intake teeatue, avoid unlanned latent ooling, boot te unioity o illed wate oening on te ille wate CRAC unit and edue igting aong ontol. Wile etieving exat eaueent i diiult, te auto obtained eeentative indie o dieent tye o ai anageent olution. Tee ae indiated in Figue 6.
Figue 6: Ai anageent olution Te ed diaond ow eaueent o atual data ente. Legay data ente, atiulaly i not well-anaged, tend to ave ig level o bot bya and e-iulation low ate, wi ae ineaed wen ubjet to ige denity load. Cabinet inlet ee to loed abinet wit ai enty o below and wit an on to o te abinet to extat eat. Geneally tee ae no blanking late witin te abinet, and inlet and exaut ai tea ae not egegated, oduing ig level o e-iulation. Bya ai i bette anaged unle tee ae a lage nube o loo gille, wi would bya ai bak to te CRAC unit. Bak-to-ont aangeent tend to ave low bya but ig level o e-iulation o te bak o te abinet to te ont o te abinet in te ae aile. Cold-aile/ot-aile aangeent, i oely deigned and oeated, an adde te ain oble o e-iulation. Howeve, atiulaly at low load, tee will be ig level o bya ai, unle oe tye o vaiable ai-low ontol i itted. Cold-aile/ot-aile ee wit all bet deign atie u a CRAH unit in galleie wit ig bay eiling (o etun eiling lenu wit duted CRAH), blanking anel, able bue, oa illow, and ontinuou ow ave own edued eiulation and bya level. Howeve, a big ootunity till exit. Fo ig denity load, tee ae eveal deign woe bai intent i to ontain and eaate te old ai o te eated etun ai on te data loo: ot-aile ontainent; oldaile ontainent; ontained ak uly, oo etun; oo uly, ontained ak etun; ontained ak uly, ontained ak etun. Te eaation an be aieved wit ad uae gla o ti utain o exale. Contained old/ot aile i a elatively new aoa and eoane data indiated vey low level o bya and eiulation.
Ioving Peoane Ideally, te data ente would ave zeo bya and eiulation ai low, and tee would alo be a balane between te CRAC and eve ai equieent (BP0, R0, NP0 and BAL1). But tat i a o te ae in eality. Fo uvey and aeent aied out by te auto, on aveage, al te ai low ate odued by te CRAC unit byae IT equient and etun to te CRAC unit witout doing any ueul ooling. And aoxiately al te ai intake to te eve i exaut ai o eve. Uing te diued ai-anageent eti, detailed alulation wee ade o a id-ange data ente wit bya and e-iulation ato o 0.5. Eliinating ailow bya an edue CRAC an enegy ue by 60kW. By eliinating e-iulation, oeo enegy aving o 74kW ae oible, due to te evaoato oeating at ige teeatue. Fo a 10,000 quae oot data ente, ti an eeent a aving o $90,000 annually. Tee etiate do not inlude ee ooling, wi a te otential to ineae aving by an ode o agnitude. How an aility exeutive iove te ai anageent o tei data ente? Fo te atial aliation te ollowing i a lit o eaue tat edue te iue o oo ai anageent. Tey ae lited in deending ode o iat and eaibility: Bya Ai: Seal ai ga in te aied loo, atiulaly able ut-out witin abinet at te diage ide o eve. Reloate loo ai gill o tat tey uly te inlet o eve tat i, eove loo ai gill o ot aile and ote aea wee ooling in t equied. Enue ai veloitie o loo gill ae not too ig, wi an aue ai to oveoot te to o te abinet. CRAC unit tuned o ae a oue o ai bya; onide ai iolation wit dae. Reiulation Ai : Fit blanking late in abinet wee eve ae not intalled. Cloe ga between abinet wee wa ai an ake it way to te eve inlet. Enue a u a oible te adequate uly o old ai to te eve inlet. Enue ai veloitie and low o loo gill ae uiient to ea te to o abinet eve. Review ai etun at to CRAC and onide etun ai lenu o dutwok i neeay. Conide ean to yially iolate te uly (old) and etun (ot) ai tea. Reove obtution unde te loo tat etit old ai to uly te eve inlet. Te eetivene o toe eaue an be een o wok done at a 5,000-quaeoot data ente. Duing an enegy aeent o te aility, eaueent wee taken o oe tan 20 eent o te eve eent and all o te CRAC unit. Te geneal data ente loo layout i bak-to-ont, but oe eve diage and intake ae on te ae ide. Te load denity wa 27 watt e quae oot. Reiulation, bya, and balane wee alulated to be 0.61, 0.21, and 0.50, eetively. Te load denity wa 27 W/t 2. Reall tat te ideal o eiulation and bya i zeo, and o balane it i 1. Clealy tee wa oo o ioveent. Inteetingly, wen tee oint wee lotted on Figue 4 above, te oint ell into te aea aked by bak to ont. Te balane atio o 0.5 indiate tat te eve ae not getting enoug ai. Tat wa attibuted to te aily low eigt (18 ine) o te aied loo wit any obtution. Te obtution eulted in low ai veloitie o te loo gill, o tat ool ai didn t ea te eve in te to o te abinet. Anote oble i tat any eve intake and diage ae loated in te ae aile. To edue eiulation and ineae balane, te aeent tea eoended bette anageent o undeloo obtution; oe eiient layout u a old/ot aile; etoitting te data ente wit a etun ai lenu; blanking-o all te unued eve loation; itting blanking anel between abinet; and itting bu eal at all able utout. Baed on eaueent taken o te data ente at te ae loation ate ileenting ot o te eoendation, new ai anageent eti wee 0.34 o eiulation, 0.18 o bya and 0.82 o balane, a ubtantial ioveent. (A negative eue atio o 0 i
aued.) Te aility anage i looking at intalling a etun ai lenu to edue te eiulation and bya low atio even oe. Leon Leaned Te ollowing leon an eve a guideline o u analye. Fo all teeatue eaueent ue a ile, eliable teoete, not lae gun ine tey eaue uae teeatue and not ai abient teeatue Meaue and aveage te atual ai outlet teeatue (uly o CRAC) and ai inlet teeatue (etun to CRAC) in a oule o loation ao te dut and not only at a ingle oint. In oe ae, tatiiation ay lead to dieent teeatue value. Te aeent tea ould ale two to tee tie a any eve a tee ae CRAC unit, eauing te eve ai inlet and outlet teeatue. Te eve ai inlet teeatue ould be taken wit a teoete a loe a oible to eve gill inlet (not at te ak o abinet inlet) witout touing any uae. Siilaly, eve outlet teeatue ould be taken a loe a oible to te eve witout touing any uae. Seve inlet and outlet teeatue ould be taken at te ae level o te ae eve. I teeatue i eaued at te eve inlet loated in te iddle o te ak, te eve outlet teeatue ould be taken o te ae eve at te ae level. Reading ould be taken o eve in a ix o loation: beginning o aile, end o aile, iddle o aile, botto o abinet, iddle o abinet, and to o abinet. Reading ould be taken o eveal aile and not jut one o two aile. Meaueent ould be taken o eveal ot ot, i ot ot exit. It i aetable to ue aveage teeatue ate tan weigting te wit a low ate/ize. Many data ente oeato take a elaxed attitude towad bya ai, wi i odued by te CRAC and etun dietly witout ooling eve. Bya ai aue a ga between te teeatue o ai odued by te CRAC unit and te teeatue o te ai at te inlet to te eve, altoug in teoy toe two ould be te ae. CRAC unit ae deigned to odue lowe teeatue o te ole eaon o oetting te e-iulation o ai o te outlet o te eve to it inlet. Ai bya alo tave eve o ai, wi ineae eiulation. One negative eue low (NP), bya low and e-iulation low ae addeed, te balane o CRAC and eve ai (BAL) beoe a neeay iue to adde. Ti will equie oe etod o autoati balane o ai to load. Ideal utue ai ooled olution will equie vaiable CRAC ai low ate a well a egegation between old ai to eve and diage wa ai o eve. Bette ai anageent witin data ente ainly iniizing bya and eiulation ailow a te otential to iove teeatue ontol o oe eliable eve ooling. It an alo ave enegy. Wat oe, ioved ai anageent i eential to axiizing data ente ee ooling ootunitie. Munte Sali, PD, i inial, enegy eiieny and utainability in te Ciago oie o HP Citial Failitie Sevie - EYP MCF. Robet Toze, PD, i tenial dieto - HP EMEA.