Air Climate System – Twin WheelReducing the cost of humidity control

Twin Wheel system– humidity control and energy saving

The Twin Wheel might not be as important to humanity as the wheel. But within the air treatment business we still consider this system a landmark innovation, and it creates a high indoor air quality as well as energy savings for the benefit of our common environment.

•The outer rotor pre-cools supply air.Thesystemtherebylowerstherequirementsonbothcoolingcoilandchiller.

•The outer hygroscopic rotor also transfers humidity from supply to exhaust air flows.Thisleaveslessmoisturetoremoveforthecoolingprocess,whichmakesitpossibletodownsizecoilsandchillersevenfurther.

•Need for heater dramatically reduced.Theinnerrotorrecoversenoughheatfromtheexhaustairflow–heatingforfreeformostoftheyear!

•The Twin Wheel is a perfect match for chilled beams and fan coils.Itlowerstheriskforcondensationonthechilledbeamthroughanenergyefficientmechanism.Chilledbeamsarethemselvesefficientpartsofacirculatingliquid-basedflow,thatbesidesenergysavingsalsolowersnoise,amountofduct-workandrequiredcapacityofmainAirhandlingunit.

This makes the Twin Wheel such a good idea:

Air quality

Todaywedemandacomfortableenviron-mentwheninsideabuilding.Oneimportantparameterforagoodindoorenvironmentistheairquality.Goodindoorairqualityinturnisacombinationoffactorslikeoxygenlevel,humidity,absenceofodorandpollution-andobviouslytherighttemperature.

Energy costs

Coolingandheatingprocessestypicallydemandhighlevelsofenergysupply.Inmodernbuildingsairtreatmentisoftenthebiggestconsumerofpower.Thisfact,togetherwithconstantlyincreasingglobalenergyprices,callforsystemsoptimizedforbestoverallefficiency.AtFläktWoodswecombineourexperiencewithadvancedtechnologyto

achieveintelligentsystemsolutions.Theyaresoundinvestmentswithshortbreak-evenanddramaticsavingsinthelongrun.

Environment

Theenvironmentisalsoawinnerwithoursolutions.Fornature,regardlessofenergysource,theleastharmfulkilowattofenergyistheonesavedandneverproduced.

Controlled humidity

Controloverthehumiditycontentoftheairisonefactortoreachgoodindoorairquality.Humiditycontrolisalsoessentialforuseof‘chilledbeams’,anaircoolingtechniquewithgoodefficiencyandhighlevelsofcomfort.

How does the Twin Wheel system work?

Fläkt Woods has designed the Twin Wheel system to improve on cooling and humidity control versus other solutions on the market. The purpose is to produce cool and dry air while lowering the cost for these processes compared to conventional systems.

The components of a Twin Wheel system

Rotary heat exchanger

Rotaryheatexhangersareusedforheatingandcoolingrecoveryinairhandlingsystemsandtypicallyenhancestheirefficiency.Therotaryheatexchangersmaincompo-nentistherotor,whichismadeofeitherthinfoldedsheetaluminiumormicro-glass,formedastriangularpipes.

Sensible rotor

Whenspinning,therotortransfersheatorcoldbetweensupplyandexhaustairstreams.Inthiscase,wheretheexchangeisrestrictedtotemperaturetransfer,itiscalleda‘sensible’rotor.Hygroscopic rotor

Throughsurfacetreatmenttherotorcanalsobegivenmoist-transferringabilities.Itisthencalleda‘hygroscopic’rotor.Thistypeofrotorcanalsorecoverenergyfromwatervapor,

whichmeansthatitcanrecoverbothsensibleandlatentenergy.Thetransferprincipleisthesameforbothmoistandtemperature.

FläktWoodsamericanSEMCO-unithasdevelopedahygroscopicrotorwithapro-prietarysurfacetreatmentof3Å(angstrom).

Thisrotorismoreefficientthantraditionaltypesinabsorbingmoist.Themoleculargridof3Åpermitswatervaportobetransferredwhilepollutions,whichtypicallyhavelargermolecules,arenotcarriedover.

Cooling recovery

TheTwinWheelcontrolleroperatesthetworotorsinsequence,resultinginloweredrequirementeffectonthecoolingcoil.

Cooling coil

Thepurposeofthecoolingcoilistocooland/ordehumidifyair.Coolingisachievedwhenwarmairpassesthroughthecoolingcoil,whichconsistsofparallelpipes.Whenthereisalsoademandforde-humidification,thetemperatureofthebatteryislowereduntilthepassingairreachesitsdewpoint.Thecondensatedmoististhenextractedbyadripseparator.Theoutcomeofthispro-cessisairwithlowertemperatureandlowerhumidity.

Controls

TheTwinWheelisequippedwithapre-programmedin-tegratedcontrolsystem,specificallydevelopedtomeettherequirementsforcosteffectiveness,userfriendliness,reliabilityandenergyef-ficiency.ThecontrolsystemisbasedonapowerfuldigitalcontrollerwithModbuscommunicationandanintegratedwebserverasstandard.Theuserinterfacein-cludesanoperatorpanel,withaneasytouse“pushandpull”navigationthroughalogicalmenustructure.ThecontrolsystemisautomaticallyselectedandconfiguredinACONandtherebysimplifiesthedesignprocessreducestimeandmoneyspentonengineeringanddocumentation.

Humidity control

TheTwinWheelcontrolleroperatesthehygroscopicrotorandcoolingcoilinsequencetoadewset-pointvalue,therebylimitingthesupplyairhumiditylevel.Duringthecauseoftheyear,thesystemwilllimitindoorhumidity.

The traditional system

Inaconventionalsystem,coolinganddryingisachievedbycondensatingawayexcessmoistureonacoolingcoil.Inthenextsteptheairisre-heatedinaheatingcoiltoreachthedesiredtemperature.Bothcoolingandheatingtypicallyrequireconsiderableamountsofenergy,leavingroomforimprovementinbothcostandenviron-mentalaspects.

Whenoutdoorairiswarmerthantheexhaustairflowthereisaneedforcooling.Thehygroscopicrotorthenreducestemperatureoftheincomingair.Simultaneouslyittransfersmoisturefromthein-boundtotheoutboundairflows(incaseswhereabsolutehumi-dityishigheroutdoors)

Afterpassingthroughthehygro-scopicrotortheairpassesthroughthecoolingcoil,wherethetemp-eratureisreducedfurtherandmoistureiscondensateddowntorequiredlevels.Sincetheairhasalreadybeencooledbythehygroscopicrotor,thedemandforcoolingislowered.Thesavingcanbeupto50%ofthenominalrequiredcoolingeffect,whileatthesametimetheneedforafollowingre-heatingbatteryinmostcasesdisappear.

Thenowdehumidifiedandcoo-ledaircontinuestothesensiblerotor,whereheatfromexhaustairisrecoveredandusedtore-heatit.Theairthenissuppliedtothebuilding,whithcontrolledlevelsonbothtemperatureandhumidity.Notethatthetemperatureexchangeinthesensiblerotor,whereexhaustairiscooled,furtherimprovesthecoolingrecoveryofexhaustairinthehygroscopicrotor!

Twin Wheel advantages in overviewThe Twin Wheel system contains three main parts; the hygroscopic rotor, a cooling coil and a sensible rotor.

1 2 3

Exhaust air

Outdoor air Supply air

Hygroscopic rotor

Sensible rotor

Cooling coil

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Airflowrate5m3/s•Outdoorcondition:29°Cdrybulb,50%relativehumidity

Requiredsupplyaircondition:20°Cwith8g/kgabsolutehumidity

Exhaustairdesigncondition:23°Cwith9g/kgabsolutehumidity

Thetotalcoolingdemandis184.4kWandthereheatdemandis56.5kW.

Withthetwinwheelsystemthefirstrotaryheatexchanger(green)recovers

100kWofcoolingleavingjust84.4kWforthecoolingcoil.Thereheatdemand

isfurnishedbythesecondrotaryheatexchanger(red)andthesupplyfan.

Laboratory testedTheTwinWheelsystemhasbeentestedinourlaboratory

underdefinedandaccuratelymeasuredconditions.

Count on savingsNow let’s see what the Twin Wheel system can achieve in real life! The situation is a typical setup where there are specific demands on both temperature and humidity to maintain a good indoor climate.

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Extract

Supply

Fan coilsFancoilsaremostcommonlyusedinareaswhereindividualroomcontrolisessential,suchashotels,privateandpublicofficebuildings,hospitalsandschools.FläktWoodscanofferclassic,cassetteandsatellitefan-coils.

ControlsFläktWoodsoffersawiderangeofintegratedcontrolsolutionsforairhand-lingandindoorclimatesystems.Factorymountedanpre-wiredcontrolswillreduceinstallationtimeandsimplifyon-sitelogistics.PreprogrammedandfactorytestedcontrolapplicationsbasedonFläktWoodsextensiveexpe-riencealsomeansafastcommissioningprocessandwillsecureareliableandenergyefficientoperationofthesystem.Basedonsupportforopenstandardcommunicationprotocols,integrationtoabuildingmanagementsystemcaneasilybecarriedoutbyanindependentsystemintegrator.

With our broad range of products and century-old experience, one thing is obvious to us; You have to look at the big picture. It is by carefully combining products into systems, utilizing smart controls, one can achieve the best energy solutions.

When the pieces fit, you get the big picture

Air handling unitsOurcomprehensiveAirHandlingUnitofferingallowsustodeliveroptimisedsolutionsforanycustomer.OurR&Dworkfocusesonreducingenergyconsumptionandcreatingfactorycompleteairhandlingsystemsolutionswithcontrols.Ourexperienceinthemarine,off-shore,pharma-ceuticalandhospitalmarketsmakesustheperfectpartnerforsuchapplications.

e3 – Fläkt Woods

Integrated advantages

FollowingtheKyotoprotocoltheEuropeanUnionhassetatargettoreduceenergyconsumption.Forbuildingsthetargetissetata22%reductionby2010.It’scalledtheEPBDdirective.

ToaddresstheneedscreatedbytheEPBDdirec-tive,FläktWoodshaspouredalotofeffortintocreatingthee3Concept.Oursolutionisabroadapproachleavingnostoneunturnedtoachieveoptimumresults.

High-performingcomponentsareanobviousstartout.Butitisbycombiningproductsintoasystem,utilizingsmartcontrol,onecanachievethebestenergysolutions.

Thee3logoisusedtohighlightproductsandsystemsthatdeliversavingsonbothEnergy,EconomyandEnvironment.

Chilled beamsInsystemswithChilledBeams,theindoorairiscooledbymeansofcoldwater.Chilledbeamscreateastableandcomfortableenvironmentbysupplyingdraughtfreecooling.ByusingChilledBeamsupto75%ofthetotalcoolingcapacitywillbehandledbythewater.Apartfromtheenergysavingitalsomeanslessductworkforair,smallerairhandlingunitsandlowernoise.

ChillersTheFläktWoodsrangeofchillersaredesignedtominimisetheoverallannualenergyconsumptioninalltypesofbuildings.FläktWoods’heatandcoolingrecoverysystems(e.g.Econet)allowforthedeploymentofsmallerchillersthanwouldotherwisebethecase.Thisleadstosignificantlyreducedinvestmentsandoperationalcost.

KaunasAKROPOLISwillbethebiggestshoppingcentreinKaunasandincentralLithuania,withawideselectionofnationalandinternationalstores.

TheAKROPOLISshoppingcentreincentralLithuaniawillattractcustomersfromalloverLithuaniaandneighbouringcountries.TheAkropolisshoppingcentreinKaunas,Lithuaniaincludesanicerink.Toavoidfogintheareaaroundtherinkitisnecessarytosupplyairatatemperatureof16°Candanabsolutehumidityof8g/kg.Theoutdoordesignconditionis27°Cand55%relativehumidity(12.3g/kg).

TwoEUairhandlingunitseachequippedwithtworotaryheatexchangerssupplyatotalof15.4m3/s.Thetotalcoolingdemandis448kWandthereheatdemandis53kW.Bymeansofthetwinrotorsystemthecoolingdemandonthechillerisreducedbyonethirdto300kWandthereheatdemandiseliminated.Notonlyistherunningcostreducedbutalsothesizeofthechillerplant.

References

FACTS AbOuT KAunAS AKROpOLIS

• 73,063 m2 total area

• Supermarket ”hyper-Maxima” - 6,778 m2

• More than 220 operators

• More than 2,500 fast food and

restaurant seats

• Over 2,759 parking spaces

• 9 million visitors a year are expected

• Multiplex cinema – 7 screens, more than

1,418 seats

Akropolis shopping center Kaunas, Lithuania

”By means of the twin rotor system the cooling demand on the chiller is reduced by one third to 300kW and the reheat demand is eliminated.

John Dalton building Manchester, England

FourTwinWheelsystemsweresuppliedtotheJohnDaltonBuildingatManchesterMetropolitanUniversity.ThisbuildingisfortheDepartmentofComputingandMathematicswhichhousestheirownteachingandresearchlaboratoriesofferingperson-centredworkingandlearningenvironmentforstaffandstudents.Researchiscarriedoutincomputerscience,intelligentsystems,computationalfluiddynamics,informationsystemsandmathematicalmodelling.

EnergyefficiencyandindoorqualitycontrolwereavitalfactorforthisProjectandtheconsultantRMJMdesignedasystemforthelaboratoriesincorporatingchilledbeamsanTwinWheelairhandlingunits,theairhandlingunitsprovidingfreshairtothechilledbeams.Wewereabletoshowtheclientthroughourdevelopmentacalculationmethodtoenableperformanceofthetwinwheelunitstobepredicted,alongwithenergyusageatallconditionstoenablepaybackperiodstobecalculated.TheTwinWheelsystemshowedamarkedefficiencyimprovementinthesummercyclereducingchillersizingbyupto50%andalsobetterinthewintercyclethanmostsystemswithheatrecovery.

FACTS AbOuT JOHn DALTOn buILDIng

• Assembly hall lecture theatre with the

capacity of 234

• Tiered Lecture theatres with the capacity

of 60–234

• Meeting rooms with the capacity of 20–60

• Computer training suites with the capacity

of 20-40

Further referencesUnilever, Kingston, UK

Manchester Metropolitan University,

UK Fitzrovia, London, UK

M W Kellog, London, UK

227 Tottenham Court Road, London, UK

Bidborough House, London, UK

Greenwich Peninsula, London, UK

We Bring Air to Life

Fläkt Woods group SA18, avenue Louis Casaï, CH-1209 Geneva, SwitzerlandTel. +41 22 309 3800email info@flaktwoods.com www.flaktwoods.com

See global website for international sales offices www.flaktwoods.com

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Fläkt Woods is a globalleader in air management.We specialise in the design and manufacture of a wide range of air climate and airmovement solutions. And our collective experience is unrivalled.

Our constant aim is toprovide systems thatprecisely deliver requiredfunction and performance, as well as maximise energy efficiency.

Air Handling units (AHus)

Modular,compactandsmallAHUunits.Designedtoensureoptimisa-tionofindoorairquality,operationalperformanceandservicelife.

Air Terminal Devices and Ducts

Supplyandexhaustdiffusersandvalvesforinstallationonwalls,ceilingorfloorareallincludedinourlargerangeandfitalltypesofapplications.

Chilled beams

Activeinductionbeamsforventilation,coolingandheating,andpassiveconvectionbeamsforcooling.Forsuspendedorflush-mountedceilinginstallation–andmulti-serviceconfig-uration.WithuniqueComfortControlandFlowPatternControlfeatures.

Residential ventilation

Acompleterangeofproductsforresidentialventilation.Consistsofventilationunits,exhaustairfansandcookerhoodsdesignedtooptimiseindoorcomfortandsaveenergy.

Energy recoveryDessicant-basedproductandsystemsthatrecoverenergy,increaseventilationandcontrolhumidity.

Fans

Advancedaxial,centrifugalandboxedfansforgeneralandspecialistapplications.ComprehensiverangeincludinghightemperatureandATEXcompliantoptions.Engineeredforenergyefficiencyandminimisedlifecyclecost.

Chillers

Air-cooledandwater-cooledchillerswithcoolingcapacityupto1800kW.Designedtominimiseannualenergyconsumptioninalltypesofbuildings.

Controls and drives

Variablespeeddrivesandcontrolsystems,alltestedtoensuretotalcompatibilitywithourproducts.Specialistteamcanadviseonenergysavingandoverallsystemintegration.

Acoustical products

Acompletelineofsoundattenuatingproducts,includingrectangularandroundsilencers,MediaFreesilencers,customsilencersandacousticenclosurepanels.

Solutions for all your air climate and air movement needsFläktWoodsisprovidingsolutionsforventilationandairclimateforbuildingsaswellasfansolutionsforIndustryandInfrastructure.