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HVAC Systems – Understanding the basis

HVAC Systems – Understanding the basis. Table of Contents Introduction to HVAC Systems HVAC System Types HVAC Piping System HVAC Air Distribution Equipments Fans and Pumps HVAC Instrumentation and Control HVAC System Commissioning. Introduction to HVAC Systems.

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HVAC Systems – Understanding the basis

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  1. HVACSystems–Understanding thebasis TableofContents IntroductiontoHVACSystems HVACSystemTypes HVACPipingSystem HVACAirDistributionEquipments FansandPumps HVACInstrumentationandControl HVACSystemCommissioning

  2. IntroductiontoHVACSystems Thisarticleintroducestheheating,ventilatingandair-conditioning (HVAC)systems.TheprimaryfunctionofHVACsystemsistoprovide healthyandcomfortableinteriorconditionsforoccupants;well- designed,efficientsystemsdothiswithminimalnon-renewable energyandair,andwaterpollutantemissions. 

  3. IntroductiontoHVACSystems ThepurposeofHVACdesignisbothhighindoorairqualityandenergy efficiency.Thesedualconsiderationsrequireanintegrateddesign approach.Rigsheating, ventilation,andairconditioning system(HVAC)createsaclimate thatallowsformaximumcomfortby nsatingforchangingclimatic ons.  ccoompempe ccoondnditi Thoughmorecostlytoinstallandmorecomplicatedtooperate,achillerplant  offersanumberofbenefitsoveralargenumberofindividualpackaged coolingunits,includinggreaterenergyefficiency,bettercontrollability, cheaperoverallmaintenance,andlongerlife.Usingacomprehensive approachtobuildingdesign,designersaroundtheworldhavesucceededat creatinghighlyefficientair-conditioningsystemsthatprovideexcellent comfortatsignificantsavings.

  4. IntroductiontoHVACSystems Heating,ventilatingandair- conditioning(HVAC)systems reducetheenvironmental impactofrigs/buildingsinseveral keyways.Themostimportant functionofaHVACsystemsis toprovidetherig/buildingsoccupants withhealthyandcomfortableinterior conditions.Acarefullydesigned,efficient systemcandothiswithminimalnon-  renewableenergyandairandwaterpollutantemissionstominimizethe environmentalimpact. Coolingequipmentthatavoidschlorofluorocarbonsandhydro- chlorofluorocarbons(CFCsandHCFCs)eliminatesamajorcauseof damagetotheozonelayer.

  5. IntroductiontoHVACSystems EventhebestHVACequipmentandsystemscannotcompensatefora faultyrigdesign.Problemsofthistypecauseinherentlyhighcoolingand heatingneedsandconsumeunnecessaryresourcesandshouldbe correctedifpossible.Conservationofnon-renewableenergythroughan intelligentarchitecturaldesignoffersthegreatestopportunityforsavings. Themostimportantfactorsinthesedesignsarecarefulcontrolofsolargain, whiletakingadvantageofpassiveheating,daylighting,naturalventilation andcooling.Thecriticalfactorsinmechanicalsystems'energyconsumption -andcapitalcost-arereducingthecoolingandheatingloadstheymust handle. 

  6. HVACSystemTypes TypesofSystemDesigns-Thereareseveralmajorheating,ventilating,andair conditioningsystemtypesinwidespreadusetoday.Theseareairsystems,hydronic andsteamsystems,andunitarytypesystems.Mostsystemsinusetodayfallintooneof thesecategories,orareacombinationorvariationofthem.Eachtypeofsystemhas advantagesanddisadvantages.  Aircooled -AircooledChillers

  7. AirCooledChillerAdvantages • Lowerinstalledcost • Quickeravailability • Nocoolingtowerorcondenserpumprequired • Lessmaintenance • Nomechanicalroomrequired

  8. WaterCooled  • SeaWatercooledChillers • FreshWatercooledChillers

  9. Water-CooledChilleradvantages • Higherefficiency • Customselectioninlargersizes • Largetonnagecapabilities • IndoorChillerlocation • Longerlife

  10. Air HandlingSystems Purposeofanairhandlingsystem Air Handling System Room With Defined Requirements Supply Outlet Air Air

  11. Objectives In the following slides, we will study the components of air handling systems in orderto: Become familiar with thecomponents Know theirfunctions Become aware of possibleproblems

  12. Mainsubsystems Exhaust airtreatment Fresh airtreatment Terminal airtreatment (make-upair) + at production roomleve Room/Cabin Central air handlingunit

  13. Overviewcomponents Exhaust AirGrille Flow ratecontroller Silence Fan Filter r Weatherlouvre Controldamper + Heater Humidifier Prefilter Terminalfilter SecondaryFilter Cooling coil ProductionRoom with Heating droplet coil Re-circulated air separator

  14. Components(1) Topreventinsects,leaves, dirtandrainfromentering Weather louvre  Silencer  • Toreducenoisecausedbyair circulation • Automatedadjustmentof Flowrate  controller volumeofair(nightandday, pressurecontrol) Control  Fixedadjustmentofvolume ofair damper

  15. Components(2) Toheattheairtotheproper temperature Heatingunit Tocooltheairtotherequired temperatureortoremovemoisture fromtheair Coolingunit /dehumidifier Tobringtheairtotheproper humidity,iftoolow Humidifier Toeliminateparticlesofpre- Filters determineddimensionsand/or micro-organisms Totransporttheair Ducts

  16. Airtypes + Exhaust air Fresh air (make-upair) Supply air ProductionRoom Return air (re-circulated)

  17. Filterclasses Dustfilters Standard Aerosol Coarse Fine Dp > 10 µm 10 µ m > Dp > 1 µm G1 -G4 F5 -F9 H 11 -13 U 14- 17 EN 779Standard EN 1822Standard

  18. HEPA or tertiaaryfilter Primarypanel filter Secondary filter

  19. Ductheaters RoomHeters Silensers

  20. Volumecontroldamper FireDampers Dryair Humid room air Adsorberwheel AHU withfan VariableSpee Controller d Regenerationair Humid roomair FilterPressure Gauges Airheater De-humidification

  21. Regulationofroompressure–pressure differentialsconcept Roompressure gauges Room pressure indicationpanel Annex 1,17.26

  22. Pressurecascadeinjectables Protectionfrommicro-organismsand particles Ro om1 Ro om2 Ro om3 A L F 30Pa 60Pa 45Pa D Air L o c k 45Pa Air L o ck B C 15Pa Air L o ck 30Pa P a s s a ge D 0Pa Not e: Di r ect i onof door opening r el at i vet oroom pr es s ure

  23. Pressure cascade solids Protection fromcross-contamination Ro om1 Ro om2 Ro o m3 15Pa 15Pa 15Pa Air L o ck Air L o ck Air L o ck 30Pa 0Pa E P a s s a ge 15Pa Not e: Di r ect i onof door openi ngr el at i vetor oom pr es s ure

  24. FanCoilUnit

  25. SelfContainUnit

  26. HVACAirDistributionEquipments Diffusers  4WayDiffusers TwoWayDiffusers OneWayDiffuser RoundDiffusers

  27. CabinUnits

  28. Return/ExhaustGrilles

  29. Fans andPumps • Contents • FanDesign • FanPerformance • Fan-ductSystems • DuctConstruction • AirDuctDesign

  30. FanDesign • Commontypesoffans • Centrifugalfans:radial,forwardcurved,air foil(backwardcurved),backwardinclined, tubular,roofventilator • Axialfans:propeller,tube-axial,vane-axial • Fanarrangements • Motorlocation,airdischargeorientation,drive traintype(directdriveorpulleydrive) • Centrifugal:singlewidthsingleinlet(SWSI), doublewidthdoubleinlet(DWDI)

  31. AXIALFANS CENTRIFUGALFANS Centrifugal and axial fancomponents

  32. AXIALFANS Propeller Tube-axial Tube-vane

  33. CENTRIFUGALFANS Tubular centrifugalfan Centrifugal roofventilator (* Note the airflow paths and impellerdesign.)

  34. Drive arrangements and motorpositions

  35. Single- and double-width centrifugalfans

  36. FanPerformance • Majorparameters • Fanvolumeflowrate(m3/sorl/s),Vf • FantotalpressureΔpttf,fanvelocitypressure • pvf&fanstaticpressureΔpsf(Pa) • Fanpower&efficiency • Fanpowerorairpower(W)=ΔptfxVf • Fanpowerinputonthefanshaft(brake horsepower),Pf • Fantotalefficiency:ηt=ΔptfxVf/Pf Combinedaerodynamic,volumetric&mechanical  efficiencies • Fanstaticefficiency:ηs=ΔpsfxVf/Pf • Airtemp.increasethroughfan,ΔTf=Δptf /(ρcpaηt)

  37. Fan performancecurves Totalpressure Staticpressure Fan totalefficiency Fan staticefficiency Fan powerinput Velocitypressure Volume flowrate

  38. Typical fan performancecurve

  39. FanPerformance FanLaws Speed(n) Volumeflow(V) Totalpressureloss (Δp) Airdensity(ρ)     Forairsystemsthat  aregeometrically& dynamicallysimilar: (D=impeller diameter) c.f.:pumplaws

  40. CENTRIFUGALFANS Velocity triangle at the blade inlet and outlet of a centrifugalfan

  41. FanPerformance • Majorissuescausingenergylossestoa centrifugalfan: • Circulatoryflowbetweentheblades • Airleakageattheinlet • Frictionbetweenfluidparticlesandtheblade • Energylossattheentrance • Partiallyfilledpassage

  42. Operating characteristics for a backward-curved centrifugalfan

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