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PowerPax, basedinMelbourne,Australia,was founded in2000bya teamofHVAC industryexperts,tospecializeinhigh-efficiencyshell-and-tubeheatexchangersandtheiroptimizationinoil-freecentrifugalchillers.
SMARDT,basedinMontreal,Quebec,wasfoundedin2005byateamofTurbocorveterans,toproduce chillerswhich optimized the energyefficiencypotential of theTurbocor compressortechnology.
TheSMARDTChillerGroupnowhaswell over2000operatingchiller installationsacross the
AllSMARDTchillers are ETL listed, have lifetimeelectricalsafety coverage, and incorporateevaporatorsandcondensersthatfullycomplywithASMEpressurevesselcodes.
Use of SMARDT chiller technology can significantly contribute to achieving Leadership inEnergy&EnvironmentalDesign(LEED™)certificationforabuilding,beitinexistingbuildings,coreandshellconstructions,ornewconstruction,becauseitcanhelpwincriticalpointsintheEnergy&Atmospherecategory.MarketresearchbytheU.S.GreenBuildingCouncil(USGBC)findsthatthestreamlinedLEEDprocess is secondonly torisingenergycostsasadriver forstrongeradoptionofgreenbuildingpracticesandthetransformationofthebuiltenvironmenttosustainability.SMARDTisamemberoftheUSGBC.STRONG SUPPORT FOR THE EPA RESPONSIBLE USE VISION
TheEPA’sResponsibleUsevision,encouragesmanufacturers,systemdesigners,andowners,toinvestinproductsandtechnologieswhichdocumentsustainabilityofthehighestefficiencies,intandemwiththe lowestemissions.SMARDT is astrongsupporterofthevisionandoftheEPA.
SMARDT works hard to minimizecomplexity in chiller design and operation,andSMARDT simplicity is reflected in lowproductoperatingcosts.Thethinkingmakessimplesense:nooil, floodedshell-and-tubeevaporation, soft start, low powerconsumption, low maintenance costs andhigh reliability,with only onemain movingpart.
SMARDT field reliability has beenoutstanding, and not surprising when oneconsiders that some 80% of all chillerproblems in the field are dueto failures incompressoroilreturn.AndSMARDTchillersusenooil.
The growing fraternity of turbocor-trainedengineers and technicians often suggeststhat total maintenance costs for oil-freechillers run at well under half the costs oftraditionallubricatedchillers.
Serviceability
Always important in minimizing operatingcosts, is ease of serviceability. Serviceaccess is swift and simple with SMARDTchillers, as is access to operating historythrough remote monitoring. Operatinghistory and compressor and chiller setpointsareallaccessibleremotelybytrainedandauthorizedservicepersonnel.
Simple BAS IntegrationIntegration with Modbus, Bacnet andLONworksbuildingmanagementsystemsisstandard, as is connectivity with mostindustry-standardprotocols.
Custom Design and Problem Solving
SMARDT design engineers are alwaysready and willing to resolve particularequipmentdesignchallenges.Forexample,high-efficiency heat recovery and free-cooling applications can all be customdesigned and supplied competitively, andcorrosion protection and other options arealsoavailable.
Multiple compressors also allow systemdesigners to save on low-load or ponychillers,becausewithaVFDintegratedinto
each compressor control, a chiller whichusesmultiplecompressorscanbeefficientlydriven right down below 10% or even 5%load.Optimization in DesignCondenser coils use aW configuration tooptimize heat rejection and footprint. Coilsare baked and double-coated and withsealededgesasstandard,soastoextendthe coil’s physical protection from
AllSMARDTchillers,whether air-cooledorwater-cooled, aredesigned to optimize theperformance of thehighlyefficientDanfoss
Turbocor oil-free centrifugal compressor.Oil-free magnetic bearing technology andvariable-speed drives deliver better IPLVefficiencies than conventional oil-lubricatedcentrifugal, reciprocating, scroll, and screwcompressors.Theyarealsohigh-speed – upto 48,000 rpm, very compact, very quiet,rugged,andreliable.ThePowerFactorisahigh.92.
Proprietary magnetic bearings replaceconventional oil lubricated bearings, which
eliminate high friction losses, mechanicalwear, and high-maintenance oilmanagement systems, to deliver chillerenergysavingsof35percentandmoreoverconventional chillers, while ensuring long-term reliability. Over 75,000 magneticbearingmachinesareoperatinginthefield,mainlyinhigh-endvacuumpumpsandCNCspindles - any innovation risk having beenlongovercome.
Turbocor’s one main moving part (rotorshaft and impellers) is levitated duringrotation by a digitally-controlled magneticbearing system. Position sensors at eachmagnetic bearing, provide real-timefeedback to the bearing control system at120 times each revolution, thus ensuringconstantlycenteredrotation.Key benefits of SMARDT chillers can besummarizedas:
Heat transfer optimization through
oil-freedesign
Extraordinarysoft-startefficiency
Rugged & built-in defense againstpowerfailure
HFC-134aozonefriendlyrefrigerant
Significantnoisereduction
Spectacularenergycostsavings
Improvedpartloadefficiencies
Heat Transfer Optimization Through Oil-
Free Design
The well-known ASHRAE study (researchProject 361) concluded that typicallubricatedchillercircuitsshowreductionsindesign heat transfer efficiency of 15-25%,as lubricant accumulates on heat transfersurfaces, denatures and blocks normalthermodynamic transfer processes.Logically,nooilinyourchillermeansnooilcontamination over time, so designefficiencyismaintainedeffortlessly.Extraordinary Soft-Start Efficiency
Thecompressor’spowerelectronics,furtherenhancedbySMARDT’s chillercontrollers,requireonly2 ampsfor start-up,comparedwith 500-600 amps for conventionalmachines. This means further savings forowners, who can reduce maximum powerloads and reduce backup generator size,costandcapacity.Rugged Built-in Defense Against Power
Failure
Each compressor hasabankofcapacitorsfor energystorage andto filter DC voltagefluctuations.Incaseofapowerfailure,thecapacitors provide continuity power to thebearings to keep the shaft levitated,allowing themotor to turn into a generatorandtopoweritselfdowntoastop.Extendedlife testing confirms the system’sremarkabledurability.HFC-134a Ozone Friendly Refrigerant
using R123, for example) enhancesustainable performance, as neither air ormoisturecanleakintothechiller.Nopurgeunit is required – a further saving. LiquidR134a refrigerant is used in SMARDT
chillers to cool critical electronic andelectromechanical components, to assuremaximumefficiencyandsafeoperation.Significant Noise Reduction
Very low sound and vibration levels areachieved, because there is no physicalcontact between moving metal parts,eliminating the need for expensiveattenuation.TestingofSMARDTaircooledchillers, with reference to AHRI standard
575, yields readingsas lowas77dBAat1meter.
Spectacular Energy Cost Savings
Compared with a new screw chiller,SMARDTIPLVenergyefficiencyisroutinelymorethan32%better.Comparedwitholder
lubricated reciprocating, screw, scroll, orcentrifugal chillers, year round energysavings with SMARDT chillers can be aspectacular 50% and more. Under AHRIconditions,SMARDTIPLVperformancecanbe as low as .33 kW/TR while part-loadefficiencycanbeunder.30kW/TR.Improved Part Load Efficiencies
US cities all demand the vast bulk of theirchiller operations at part load – enablingmuchloweroperatingcostswithaSMARDToil free chiller, compared with a lubricatedalternative.
The SMARDT range of chillers offer thesmallest footprint, the quietest operation,and some of the highest operatingefficienciesonthemarket.SMARDT’s Air-Cooled centrifugal chillerconsistsofashell&tubeevaporator,twin-turbine centrifugal compressor(s),compressor controller(s), hot gas bypassvalves, air cooled condenser coils,condenser fans, refrigerant level sensor(s),electronic expansion valve(s),interconnecting refrigerant piping, and
safety features such as triple freezeprotection. Condenser coils use a Wconfigurationtooptimizeheatrejectionandfootprint, sealed edge coils arebakedanddouble-coated as standard to extend thecoil’s protection from environmentalcorrosion, and all SMARDT chillers aredesignedtooptimizetheperformanceofoil-
free centrifugal compressors fromDanfossTurbocorCompressorsInc.TheSMARDTchillersetisapackagedunit,requiring connection to the chilled watercircuit, main electrical supply, andintegration with the building automationsystem(BAS)ifapplicable.The following protocol interfaces areavailable on SMARDT chillers for BAS:LON, BACNET, BACNET/IP, N2, andMODBUS/IP, and these interfaces are
usually installed within the SMARDT maincontrolpanel.SMARDT chillers deliver a high level ofreliability, outstanding part-load efficiency,andthelowestoverallcostofownershiponthemarket.
SMARDT’s Kiltech controller is very user-friendly, highly intuitive, and allowsoptimization of both single and multiple
compressoroperationwhilstenablinga richarrayofcommunicationoptions.SMARDT chiller controllers have beendevelopedfromthegroundupusingprimarycompressorperformancemaps,maximizingtheperformancepotentialwithinthese,thenoptimizing the whole chiller’s operation tominimizeenergyconsumptionThecompressor’son-boarddigitalcontrollerproactivelymanagescompressoroperation,
while allowing external control and web-enabled monitoring of performance andreliabilityinformation.
ThePowerPaxmicroprocessorsystemhasbeenusedonmanychillersites,andthein-field experiencegained has resulted inthe
generation of state-of-the-art controlssoftware that both maximizes operatingefficienciesandminimizesmaintenanceandoperatingcosts.
TheSMARDTKiltechcontrollerprovidesforseveral access levels for plant operatorsand for commissioning, and offers a widevarietyofoptions for flexibleoperationandoptimizationofpowerconsumption,therebymaximizing time spent operating atcompressorsweetspots.
Allapplicablecodes shouldbe adhered to.The Limited Product Warranty does notcoverdamagedequipmentcausedbywiringnon-compliance, an open fuse resultingfrom an overload, a short, or a ground.Correct the causeof the open fuse beforereplacing the fuse and restarting thecompressor.Compressormotorsaredesignedtooperatesatisfactorilyoverarangeof±10percentofthestandarddesignvoltage.
ELECTRICAL WIRING
All electrical wiring connecting to the unitshouldbemadeofcopper. All wiring must be installed in accordancewithappropriatelocalandnationalelectricalcodes, andwill require a circuitbreaker orfusestoprotectthemainwiringrunfromthefinaldistributionsub-boardtotheunit. According to specific model and/or option
selected, field wiring connections willrequireeitheroneortwosupplyconductorsinparallel.EachSMARDTChilleris providedwitha 3pole power distribution block or busbarsystem, splitting field supply main powerintomultiplesecondarycircuits.
Groundlugsarelocatednexttofieldwiringterminalsforequipmentgrounding.Minimum required bending space atterminals and means for strain relief ofsupply conductors, shall be provided byinstallation contractor to prevent leadsseparating from their terminations, orsubjecting them to damage from sharpedges.All electrical wiring connecting to the unitshallonlybemadeofcopperand shall be
shieldedand grounded. It isassumed thatsupply conductors rated 75 C (167 F) willbeusedindeterminingthesizeofterminals.The main power input connection for theSMARDTrangeofchillers is asinglepointtermination via a main termination box(suppliedasstandard)oneachchillerunit. All power wiring from this point on, is theresponsibility of the installation contractor.From the main termination box, eachcompressor control box (power and
controls) is pre-wired to the individualcompressors. All wiring must be installed in accordancewithappropriatelocalandnationalelectricalcodes, andwill require a circuit breaker orfusestoprotectthemainwiringrunfromthefinaldistributionsub-boardtotheunit.
WhentheSMARDTchillercontrolsystemissetto“HVAC_COOL”mode ,indicatingthechilleristo beused to control the leaving chilledwatertemperature (LCWT) to a desired value, thefollowingdescriptionofoperationistrue:EVAPORATOR DESCRIPTION
Whenthechillerisoperatedincoolingmode,thecondensed liquid refrigerantexits theelectronicexpansion valve (4) Figure 7, and enters the
bottom of the flooded evaporator, where it isevenly dispersed along the length of theevaporator bythe use ofadistributorplate (3).Liquid refrigerant inside the evaporator at lowpressure then makes contact with the coppertubes that the building’s water runs through,exchangesheattotherefrigerant,andvaporizesit(2)atthesuctionpressureof thecompressor(1).Asaresultofthelowerdensityofthevaporandthesuctionofthecompressor,thevaporizedrefrigerant gas is then drawn to the top of theevaporatorthroughthemisteliminators(5).(Mist
eliminators inhibit minute liquid particlesentrained in the vaporized refrigerant, fromentering the compressor). Passing through the(pre-rotation)inletguidevanes(6),thevaporizedrefrigerantthen enters thecompressorinlet (7),where the angleof incidence of the refrigeranthittingthefirststageimpeller,isaltered,therebyallowing a higher compression efficiency for agivencompressorrotorspeed.
Figure7:EvaporatorRefrigerantFlow
COMPRESSOR DESCRIPTION
SMARDT oil free chillers exclusively useTurbocor variable speed magnetic bearingcompressors(Figure8)onallchillers.AlloftheTurbocor compressorsarea two stage design,meaning the compression of the vaporrefrigeranttakesplacethroughtwoimpellers.
Figure8:TurbocorCompressor-ExternalViewThe refrigerant enters the suction side of thecompressorasalow-pressure,low-temperature,super-heated gas - ref Figure 9, (1). Therefrigerant gas passes through a set ofadjustable inlet guide vanes (IGV) (2) that are
used tocontrol thecompressor capacityat lowloadconditions.The first compression element that the gasencountersisthefirst-stageimpeller(3),andthecentrifugal force produced by the rotating
impeller results in an increase in both gasvelocity and pressure. The high-velocity gasdischarging from the impeller isdirected to thesecondstageimpeller(4)throughde-swirlvanes(5). The gas is further compressed by thesecond stage impeller and then dischargedthroughavolute(6)viaavane-lessdiffuser(7).(Avoluteisacurvedfunnelincreasinginareatothe discharge port. As the area of the cross-sectionincreases,thevolutereducesthespeedof the gas and increases its pressure.) Fromthere, the high-pressure/high temperature gas
exitsthecompressoratthedischargeport(8).
Figure9:TurbocorCompressorCrossSection
Figure10:PressurevEnthalpyCapacity control on SMARDT chillers isachievedbyvaryingthespeed,inletguidevaneposition,andnumberofoperatingcompressors.Figure11providesagraphicalrepresentationofthe centrifugal compressor’s response todemandandoperatingconditions.
Superheated refrigerant from the compressorentersatthetopofthecondenserbarrelwhereitis dispersed by a deflection plate. As therefrigerant is moving around the tubes in the
condenser, heat is being constantly removedfromtherefrigerantanddissipatedtothecoolingwater that is moving through the condensertubes.HOT GAS VALVE CONTROL
The hot gas valve provides the followingfunctionality:
Capacitycontrolatlowload.
Assistedpressure ratio relief for starting
newcompressors.
Head pressure relief for heat pump andaircooledchillersoperatingabovedesignconditions.
Low Load Capacity Control Functionality
Hot gas control of leaving water temperature(LWT) is a last resort method of control whenspeedcontrolandinletguidevanecontrolisnolongeranoption.Thehotgasvalvecontrolusesthecompressor’sIGV%surge.Chokeandactual
rpmdeterminewhentousethehotgasvalveforcapacitycontrol.The set point for the hot gas control is adifferential temperature below the leavingtemperature set point. By using a differentialtemperature, the hot gas control set pointautomatically adjusts with a change in supplytemperaturesetpointforthechiller,suchthatitis easy to implement alongside set point resetstrategies. AsthediagraminFigure11shows,thehotgasvalve is only used once the compressors haveusedupallspeedand IGV controlenvelopes.Ifthechiller’scapacitymustbeincreased,andthehotgasvalveis in the openposition, the valvewill close before adjustment is made forincreasedcompressordemand.
It should be noted that the hot gas capacitycontrolofSMARDTaircooledchillers,onlytakesplace when the last compressor is operating.The chiller control system makes best use of
compressor stagingbefore resorting tohot gascontrol. Under normal air conditioning loadswheretheoutsideair temperatureand theheatloadappliedtothechillerarecloselyrelated,itisnot uncommon for the hotgas capacitycontrolvalvenevertobeused.Assisted Pressure Ratio Relief
Major reasons forrequiringpressure ratio reliefwhen turning on one or more additionalcompressors within a refrigerant circuit where
isaninherentweaknessofallcentrifugalcompressors which do not incorporatepressureratiounloading.To reduce the potential of rotatingcomponentdamage.High dynamic forces can impacttraditional bearing technologysignificantly.Withtheincorporationoftherevolutionary magnetic bearing designused in the Turbocor compressor onSMARDT chillers, the potential forrotating component damage is greatlyreduced, in that shutdown can occurbeforeanysurfaceimpacttakesplace.
– Large sudden amperage spikesontheinvertercanbedangerous,duetolowthermalinertiaonInertGateBy-polarTransistors(IGBT).Thehighertheheadthatmustbeovercome, the higher the
amperagespikes.
Control Strategy
Theassistedhotgasbypassstartupisenabledwhenever the chiller enters the “STAGE UP”mode,andthepressureratiocalculatedfromthehighest discharge pressure and lowest suctionpressure of all compressors online, isabove aconfiguredlimitdefaultpressureratioof2.2.
If hotgaspressureratio assistance is required,the hot gas valve is forced open at 1% persecond,untilthepressureratioisreducedbelowthe limit at which the next compressor is startenabled.Oncethenewcompressorhasstartedand is runningwithin 10% of the speed of theother compressors, the hot gas valve isclosedslowlyatarateof0.5%persecond.
Return Water Control
Occasionally, insteadofsupplying chilledwatercontrol,SMARDTchillersareselectedtoprovidereturn water temperature control in a plant.Return water temperature control allows theleaving chilled water set point to automaticallyfloat with the actual building load. Runninghigher leaving chilled water temperatures
permits a higher chiller performance – anefficiency increase of approximately 3% per0.5°C(1°F)increaseinsetpointispossible.Selecting “HVAC_RET” mode on the chiller’sgraphicaltouchpadinterfacewillenablecontrolfromthereturnwatertemperature.Allalarmandfaulttrippointsareactiveinthismode,andextracare must be taken when selecting a returnwater temperature to run, to avoid driving thechiller into low suction pressure or low leavingchilled water faults. SMARDT suggests a set
Chilled Water System _____________________________________________________________________________
SMARDTCHILLERGROUPTD – 0081B 30
CHILLED WATER SYSTEM
EVAPORATOR WATER CIRCUITS
Chiller performance and efficiency can beadversely affected by contaminants in thewatercircuits,andsuchcontaminantscouldimpede or block the flow of water throughthecircuitorreducetheperformanceoftheheatexchanger.Strainersshouldbelocatedontheinletsideoftheevaporator,returnwatertothechillermustbeconnectedto thelowerconnectionof the evaporator, and all external waterpiping must be cleaned or flushed beforebeingconnectedtothechillerset.
Water circuits should be arranged so thatpumps discharge through the evaporatorandarecontrolledasnecessary,tomaintainessentially constant chiller water flowsthroughtheunitatallloadconditions.To ensure the chiller’s performance andlongevity, air must be purged from bothwaterboxesontheevaporator,andfromtheentirewatercircuit.CHILLED WATER PUMPS
Make all connections prior to filling withwater.Runapreliminaryleakcheckbeforeinsulating the pipes and filling with water.SMARDT recommends consultingauthorities in order to be compliant withlocalbuildingcodesandsafetyregulations. Additionalconsiderations,asfollows,shouldbemadewhendesigningthepipingsystem:
All piping systems should include
temperatureandpressuremeasuresat the evaporator. Make these
Chilled Water System _____________________________________________________________________________
SMARDTCHILLERGROUPTD – 0081B 31
Protect water from freezing by
insulatingwaterpiping.Ensurethere
is a vapor barrier on theoutsideof
the insulation, in order to protect
from pipe condensation within theinsulation.
Note: If glycol or propylene is added forfreezeprotection,thiswillcauseapressuredrop, whichmay then result in the loss ofperformance. Only use glycol with factoryapproval.WATER VOLUME
When designing the chilled water system,consider:
Theminimumcoolingload.
Theminimumplantcapacityduringa
lowloadperiod.
The desired cycle time for the
compressor.
Ifthechillerplanthasa reasonableturndown, the water volume should
be two to three times the chilled
water gpm flow rate. If the system
components do not provide the
required water volume, add a
storagetank.
VARIABLE WATER FLOW
A large rangeofSMARDTchillersarewellsuited to installations where the chilledwater and condenser water flow rates arechanged in the chiller, relative to theinstantaneous building load and outdoorconditions.WhenapplyingSMARDTchillersto variable volume (variable speed)pumping applications, the designer mustmake sure SMARDT’s design parametersaremetasfollows:
1. Thatwaterflowshallnotbealtered
atarategreaterthan10%per
minute.
2.
That the water flow rates shall notexceed themaximumandminimum
flowsdetailedinthechillerselection
sheet.
Variablespeedpumpingisadesignfeatureof the SMARDT air-cooled chiller, whichreduces the water flow through theevaporator as the load decreases. Thisfeature will function successfully if thedesign and minimum flow rates are notexceeded.Checkindividualratingsheetsformaximumandminimumflowrates.OPERATING LIMITS
Chilled Water System _____________________________________________________________________________
SMARDTCHILLERGROUPTD – 0081B 32
Maximum non-operating inlet fluid
temperature=38 C(100 F)
FLOW SWITCH
Aflowswitchfor thechilledwatersystemisnecessarytoensureadequatewaterflowtotheevaporatorbeforestartingtheunit.Priortostartingtheunit,andtoensureadequatewaterflowtotheevaporator,itisnecessarytoinstallaflowswitchforthechilledwatersystem. A flow switch will guard againstpossible evaporator freezing, should waterflowbeinterrupted.Theflowswitchistobefieldinstalledinthechilledwaterpipingandwiredtothecontrolpanelbythe installationcontractor.
HIGH PRESSURE LOW PRESSURE
SWITCHES
The High Pressure (HP) & Low Pressure(LP) switches provide an additional safetyfeature, which prevents overpressure or
Table4:PressureReliefValveParametersSMARDT Air Cooled chillers are suppliedwithdualpressurereliefvalvesmountedontheevaporator.Thevalvesareconnectedtoa changeover manifold. Using a commonbody chamber that serves as the base for
twoindependentreliefvalves,asystemcanremain fully operational when valves needtobeservicedandreplaced.
Chilled Water System _____________________________________________________________________________
SMARDTCHILLERGROUPTD – 0081B 33
All pressure relief valves on SMARDTchillers have been sized, selected andsupplied in accordance with ASHRAE 15and the ASME unfired pressure vesselcode.AlldischargeratesarecertifiedbytheNationalBoardofBoiler
The ASHRAE 15 Safety Standard forRefrigeration Systems provides guidelinesfor sizing refrigerant relief valves and ventpiping. Without attempting to provide acomplete and thorough interpretation, thisdocument provides the necessary data toproperlydeterminepipingrequirements.
VENT LINE SIZINGPiping. ASHRAE 15-2004, Section 9.7.8outlines acceptable relief piping locationsand sizing. Summarized, the relief pipingshould vent R-134a refrigerant at least 15feetabovegroundlevelandatleast20 1feetfrom any window, ventilation opening, orbuilding exit. The discharge piping shouldpreventadischargedrefrigerantfrombeingsprayed directly on personnel and preventforeignmaterialordebrisfromenteringthepiping. Additionally, discharge piping for afusible plug or rupture disc shall haveprovisions to prevent plugging the pipe intheeventofadischargebytheplugordisc. As indicated in SMARDT InstallationInstructions (Form 160.73-N1), each ventlinemust contain a dirt trap in the verticalsection to allow collection and removal forany stack condensation or debris. ThepipingMUSTbearrangedtoavoidstrainonthe relief valves – SMARDT recommendstheuseofaflexibleconnector .Theventline
should be sized in accordance with ANSI/ASHRAE 15, and local codes, butshouldneverbesmallerthanthereliefvalveoutlet sizes provided in specific chillerdocumentation.Common Header
thesameormultipleunits)tobeconnectedintoacommonlineorheader.Thesizingofthe common discharge header and ventpiping for relief devices - expected tooperatesimultaneously-shallbebasedonthe sum of their outlet areas, with due
allowance for the pressure drop in alldownstreamsectionsandback-pressure resulting from thedischargeofmultiplereliefdevices.
Maximum Length. ASHRAE 15 section9.7.8.5 and Appendix H define themaximum length of discharge pipingdownstreamofthepressure-reliefdeviceas:
(ft)Cr= rated capacity as stamped on thedeviceinkg/sec(lb/min)f= moody friction factor in fully turbulentflowd= inside diameter of pipe or tube, mm(inches)ln=naturallogarithmP2= absolute pressure at the outlet ofdischargepiping,kPa(psia)P0=allowedbackpressure(absolute)attheoutletofpressurereleasedevice,kPa(psi)
= (0.15 x relief valve set pressure +atmosphericpressure)The ASHRAE15usersmanual states thatwhen the length of the vent pipe exceedsapproximately 220 diameters (L/d > 220),thefirstterminequation(2)aor(2)bmaybeusedtosolveforthediameter,d.
Chilled Water System _____________________________________________________________________________
SMARDTCHILLERGROUPTD – 0081B 34
2.0
2
2
2
0
2
36.1 P P
fLC d r [inches]Eq.(3)a
2.0
2
2
2
0
2
2521
P P
fLC d r [millimeters]Eq.
(3)b Anaveragefrictionfactorf=0.02,maybeusedwhenthepipesizeisnotknown.Thissectiononthedischargeventlineistobe used as a guide only. For a completedescriptionof the relief valve vent line sizing, pleaserefer to ASHRAE Standard 15 or localoverridingcodes.
A. Dimensioned plan and elevationdrawings, including required serviceclearancesandlocationofallfieldpipingandelectricalconnections.B. Electrical and water qualityrequirements during operation, standbyandshutdown.C. Control system diagram showingpointsforfieldinterfaceandconnectionto external BMS systems. Drawingsshallshowfieldandfactorywiring.
A. Regulatory Requirements:Compliance with the standards inSection1.2.1.5 DELIVERY AND HANDLING
A. Chillers shall bedelivered tothe jobsite completely assembled (unlessotherwisespecified).
B. Compliance shall be with themanufacturer’s instructions fortransportationandrigging.
1.6 WARRANTY and MAINTENANCE
A. The chiller manufacturer’s warrantyshall be for a period of one year fromdateofequipmentstartupor18monthsfrom the date of shipment, whicheveroccursfirst.B.Thewarrantyshall includepartsandlaborcostsfortherepairorreplacementofpartsfoundtobedefectiveinmaterialorworkmanship.C.Maintenanceofthechillerequipmentwhileunderwarranty,ismandatoryandshall be the responsibility of thepurchaser, unless supplied by themanufacturer.Optional:
B. Approved Equal. Note approvedequal does not automatically imply thealternate product matches thisspecification, functionality or deliveredquality.2.2 PRODUCT DESCRIPTION
A. Provideandinstall asshownon theplans, a factory assembled air-cooledpackagedchiller.
B. Eachunit shall includeone ormoreTurbocor oil-freemagnetic bearing andvariable-speedcentrifugalcompressors.Integratedvariablefrequencydriveshalloperate with inlet guide vanes tooptimize part load efficiency. ChillersshalloperatewithHCF-134arefrigerant- not subject to phase-out by theMontreal Protocol and the U.S. EPAcleanairact.C. The evaporator, condenser, andexpansion valve shall be configured tooperate as a single refrigerant circuitunless otherwise specified. The chillerunit compressors shall bedesigned formechanical and electrical isolation tofacilitateserviceandremoval.
2.3 DESIGN REQUIREMENTS
A. Unit shall consist of one or moremagnetic bearing oil-free centrifugalcompressors with integrated variablefrequency drive, refrigerant flooded
evaporator, air cooled condenser, andoperating controls with equipmentprotection.B. Performance: Refer to schedule forspecific operating conditions. Whenutilizing Turbocor model TT300compressorsthechillershallbecapable
of stable operation down to 20 tons.When utilizing Turbocor model TT350compressors, the chiller shall becapableofstableoperationdownto35tons.All these ratingsaremeasuredatstandard AHRI entering condenser
watertemperaturesandwithoututilizinghotgasbypass.
C. Acoustics: Sound pressure for theunitshallnotexceed83dBA,measuredat1meter(3.28ft).Sounddatashallbemeasured according to AHRI Standard370.
Global 63 125 250 500 1k 2k 4k 8k
D. Chiller shall beequipped for single-pointpowerconnection.2.4 CHILLER COMPONENTS
A.Compressors:
1. Compressors shall be of semi-hermeticcentrifugaldesignandoperateoil-freewithtwo-stagesofcompression,magnetic bearings,movable inlet guidevanesandintegratedvariablefrequency
drivesystem.2. Automatically positioned andcontrolled inlet guide vanes shalloperatewithcompressorspeedcontrols.3. The compressor shall be capable ofcomingtoacontrolledstopintheeventof a power failure. The unit shall becapable of initializing an automaticrestartinthecaseofpowerfailure.
4. Each compressor shall haveintegrated microprocessor controlcapableofcapacityandsafetycontrol.5. Each compressor shall be installedwith individual suction, discharge andmotor cooling refrigerant line isolationvalves. Chillers without discharge lineisolation valves that rely on non-return
valves in the discharge line forcompressor removal, shall not beaccepted.6. Each compressor shall have anindividualdisconnectswitch.Onchillers
that are provided with more than onecompressor, each compressor shallhavemechanicalandelectrical isolationto allow the chiller to operate when acompressorisremoved.Optional:
1. EMI filters installed for eachcompressor.B.Evaporator:
1. Evaporator shall be shell-and-tubetypeandshallbedesigned,constructed,tested and stamped according to therequirements of the ASME Code,Section VIII Code Case 1518-5.Refrigerant shall be in the shell andwaterinsidethetubes.Thewatersidesshallbedesignedforaminimumof150psig or as specified. Vents and drainsshall be provided. The refrigerant sideshall bear the ASME Code stamp.Vesselsshallpassatestpressureof1.1timestheworkingpressurebutnotlessthan 689 kPa (100 psig). Provideintermediate tube supports spaced toenableequalliquidandgasflowacrossmultiple compressor suction ports. Theevaporatorwaterconnectionsshallalsobeequippedwithright-handor left-handconnection,interchangeable.
2.Aperforatedplatedesignedforvapordisengagementshallbe installed insidethe evaporator above the tubing, to
ensure effective liquid droplet removal,to prevent liquid damage tocompressors, and to equalize suctionpressure across evaporators withmultiplecompressors.3.
Tubes shall be individuallyreplaceable and have internally and
externally enhanced surfaces designedfor refrigeration duty.Tubes shall havesmooth full tube wall landings at thetube-sheet ends and at intermediatetube supports. Tubes shall bemechanically roller expanded intosteel
tube sheets containing a minimum ofthreeconcentricgrooves.4. Minimum evaporator exiting watertemperature shall be 3.3°C (38°F).Minimum entering condenser airtemperature shall be 0°C (32°F).Minimum inlet condenser air to outletchilledwaterdifferenceshallbe-11.1°C(12°F).5. The evaporator, including chilled
water boxes, compressor suction line,compressor end bell, and all othercomponents, subject to condensingmoisture, shall be insulated with ULrecognized¾inchclosedcellinsulation. All jointsand seams shallbe sealed toformavaporbarrier.Optional:
1. Marinewaterboxes.
2. Epoxy-coating of inside surfaces ofwaterboxesandtubesheets.
3. Water sidevessel design for of 300psioperation.
1. Air cooled packaged chillers andcontrols shall be capable of reliable
operation between 0°C (32°F) and40.6°C(105°F)ambientairtemperature.2. Air-cooled condensers shall utilizemill-coated hydrophilic-blue aluminumfinswithrefrigerationdutycoppertubesmechanically expanded into fin collars.Condenser coilsshallbearranged ina
W-configuration to reduce equipmentfootprint.3. Condenser coils and fans shall bearranged such that one fan operateswithonecoilsectionsothatthefailureof
afanwillnotaffecttheCFMacrossanycoil beyond that fan. The standardcoating shall meetASTMB117 2000hrsaltspraytest.4.Thecondensershallbeequippedwithanoversizedliquid lineandmechanicalfloat to ensure liquid sub-coolingnecessary for effective cooling of thecompressor.5.Thecondensershallbeequippedwith
packaged fixed or variable speed fanscapable of delivering specified CFM ofairaccordingtoARIstandardoperatingconditions.Thefanmotorsshallbehighefficiency, direct drive, 3-phase,insulation class “F”, current protected,Totally Enclosed Air Over (TEAO),double sealed and with permanentlylubricatedballbearings.6. The fans shall be low sound. Theyshall be balanced dynamically andstatically and direct drive. Also, theblades shall be corrosion resistantdesignedfor lownoise, full airfoil crosssection, providingvertical air dischargefromextendedorifices.Theguardsshallbeconstructedofheavyduty14gaugesteelandpainted.Optional:
1. The coating system for HVAC coilcorrosion resistanceprovidesa lifetimeprotection against micro-organism
contamination that causes unwantedodors,andshallpassa10,000hoursaltspray test. Next to anti-corrosionprotection and energy conservation ofthe total system, the coating shallprevent adhesion of dirt and growth ofmicro-organisms,andshallalsoprevent
Controlofrefrigerantflowshallutilizeasingleormultiple6,000stepelectronicexpansionvalve(EXV),tooperatewithinthefullrangefromfullloadtothelowestloading capacity for the chiller. Fixedorificemeteringdevicesorfloatcontrolsusing hot gas bypass are not
acceptable. The EXV liquid line shallhave a sight glass with moistureindicator and temperature sensorconnected to the control system forvalidationofsub-cooling.2.Thecondensershallbeprovidedwithacapacitivetypeliquidleveltransducerwitha resolutionofnot less than 1024discretesteps. The transducer shall bewired to the chiller control system.Condenser liquid level measurementshallbeusedintheelectronicexpansionvalve controlalgorithmwith aminimumlevelsetpointtoensureadequateliquidseal ismaintained inthe condenser, toprovide compressor motor coolingduringoperation.Condenserliquidlevelshall be clearly displayed on thegraphical operator interface in aminimum of two screens. Chillerswithout direct level measurement areprohibited,duetopossibleoverheatingdamagethatmayoccurincompressorswhenliquidsealislost.
3. Each compressor shall be installedwith individual suction, discharge, andmotor cooling refrigerant line isolationvalves. Chillers without discharge lineisolation valves that rely on non-returnvalves in the discharge line for
compressor removal, shall not beaccepted.4. To prevent unit operation with nowater flow, factory mounted and wiredthermal dispersion water flow switches
shallbeprovidedonthecondenser.5.Thecondensershallbeequippedwitha mechanical stainless steel float forelectronicactuationoftheEXV,soastoprovide a positive liquid seal toensureeffectivecoolingofthecompressor6.Theevaporatorshallbeprovidedwithspring loaded reseating type pressurerelief valves, in accordance with ASHRAE-15. Rupture discs are not
acceptable.7. Load balancing valves shall beprovided for capacity control andadditionaltemperaturestability.8. There shall be a backup superheatcontrolontheinletofthecompressor,inordertocontroltheEXVintheeventofafailure of the primary level sensingdevice.E.PrimeMover:
1. A permanent-magnet, synchronoushermetically sealed motor of sufficientsize to effectively provide compressorhorsepower requirements. The motorshall include soft-start capabilities withan in-rush current of no more than 2amps (TT300 models) and 4 amps(TT400 models). The motor shall beliquid refrigerant cooled with internalthermal overload protection devicesembeddedinthewindingofeachphase.
2.Thecompressormotorandchillerunitshall include variable frequency speedcontrols tomatchcooling load demandto compressor speed and inlet guidevaneposition.
3. Each compressor shall be equippedwith an AC line reactor and individualdisconnect.F.ChillerFrame&Housing
1. All components shall be mountedonto a unitized construction, having agalvanized welded steel frame suitableforoutdoorinstallation.2. Compressors and controls shall becontained within a sheet metalenclosuretoprotectcriticalcomponentsfromtheweather.G.ChillerControls
The controller fitted to the oil-freecentrifugal chiller package shall be anembedded real time microprocessordevice that utilizes control softwarewritten specifically for chillerapplications. User operation shall beaccomplished using a panel mountedcolortouch-screeninterface.Thestatusof the compressors and all systemparameters, including compressoralarmsandtemperaturetrends,shallbeviewable.G1.Thechillercontrolsystemshallhavethe capability of storing one year ofoperationaldata.Nolessthan60pointsof information shall be sampled at amaximumof15minuteintervals.G2.Thechillercontrolsystemshallhavefullwebbasedremotecontrolcapability;including the capability of remoteoperationandsoftwareupdates.Controller features must include the
following:
1. Selectable control mode – leavingchilledwater, entering chilled water, orsuctionpressurecontrol.2.
10.4-inch or 12.1-inch or 15-inch,65,000 colors, touch panel operator
interface operating windows XPembedded.3. Chiller documentation shall beviewableviatouchpanelinpdfformat.
4.
Operatorinterfaceshallbecapableofconnecting directly to compressors viaserial communication protocol anddisplay compressor information usingTurbocor compressor monitoring /commissioningsoftware.5. Chiller control panel shall contain aminimumofthreeprocessors;allcontrolfunctionality shall be carried out on adedicatedreal timeprocessoranddataserved to a remote graphical user
interfaceviaanopenEthernetprotocol.Proprietary protocols between any pcbased or micro based processor arestrictlyprohibited.6. ChillercontrolsshallbenativeBacNetcapable via MSTP or IP. Addition ofgateway devices or additionalprocessors or pluggable PCBs toachieveBacNet communications to theBASisstrictlyprohibited.7. CompleteconfigurationofnativeBAScommunications via Modbus RTU,Modbus TCP/IP, BacNet MSTP andBacNet IP shall be made via standardchillercontrollergraphicaluserinterface.Chiller controls that utilize externalsoftwareconfigurationtoolstoconfiguretheseprotocolsareexplicitlyprohibited.8. Chiller control shall be capable ofcontrolling up to eight Turbocorcompressors on up to eight individualrefrigerant circuits serving the same
chilledwaterstream.9. Chiller control panel user interfaceshallbecapableofremotecontrolviaaninternet connection without the use ofany third party gateway device oradditionalhardwareorsoftware.
10. Chiller control shall be capable ofoperating in headless mode (no touchpanel connected) and utilize standardwindows XP or higher computer todisplay user interface via Ethernetconnection.
11. Real time chiller control processorshall be capable of e-mailing apredefined list of recipients, should afault occur. E-mail shall include detailsof fault, possible reason for fault,attachmentofmonthlydatalogof195ormore compressor and chiller variables,andataminimumintervalof30secondsandwithindicationofseverityoffault.12. Ability to place all outputs in a
manual state (hand, off, auto) viagraphicaluserinterface.13. Alarm screen shall be capable offiltering faults into specific categoriessuchascompressor,chillerandsystemfaultsinordertoproviderapiddiagnosis,andseparationoffailuremodes.14. Variable speed cooling towercontrol.15.
Optional variable speed condenserwaterpumpingcontrol.16. Optional ability to turn on/off dutystandbychilledwaterpumps.17. Optional ability to turn on/off dutystandbycondenserwaterpumps.18. Optional ability to operate chillerisolationvalvesforbothevaporatorandcondenser.
19.
Multiple compressor stagingalgorithmshalloperateattheoptimizedpower curves of each compressorsimultaneously, and shall resetautomatically every second duringoperation.Compressorstagingmethodsthat operate using simple incremental
Ramp rate control - Peak energydemandlimitingalgorithms.25. Three levels of alarm safety forminimumchillerdowntime.26. Chillercontrolsoftwareshallemployan active fault avoidance algorithm toreduce chiller capacity and/or powerlevel in the case of the chillerapproachingwithin10%ofanytriplimitvalue such as suction pressure,discharge pressure, chiller amp limit,leaving chilled water temperature limit,etc...27. Store up to 32,000 alarm and faulteventsstoredwithdate/timestamp.28. Realtimedatatrendingviewableviatouchpanel.29. Chiller load profile charts viewableviatouchpanel.
30.
Chiller control graphical userinterfaceshall be capable of displayingdata inSIor I-P unitswithoutaffectingcontrolorBASprotocolunits.
Optional:
1. BMS interface module for theinterfacewith BacNETMSTP, BacNETIPorLonTalkFT10isstandard.
Data on Main Display Screen shall
include:
a) Entering and leaving chilled water
temperatures.b)
Enteringandleavingcondenserwatertemperatures.c)
Currentoperatingstateofchiller.d) Activetimers.
e)
Chillerenablestatus.f)
Chillerwaterflowproofstatus.g)
Condenserwaterflowproofstatus.h)
Indicationofcompressorreadiness.i)
Indicationofclearancetorun. j)
Chillersetpoint.
k)
TotalchillerkW.l)
Totalchillercurrentinput.m)
Three pages of data trends withzoomfunctionality.n)
Graphical dial indicators that clearlyindicate safe and unsafe operatingvalues.o)
A. Unitsshallbe field chargedwithant.HFC-134arefrigerant.
B. Factory Start-Up Services: Providefactorysupervised start-upon-site foraminimum of two working days andensure proper operation of theequipment.Duringtheperiodofstart-up,the factory authorized technician shallinstruct the owner’s representative inproper care and operation of theequipment.