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COMMERCIAL BUILDING SERVICESFLOW THINKINGChilled Water System Presentation

COMMERCIAL BUILDING SERVICESConstant Volume DistributionFLOW THINKINGConstant Volume Distribution

COMMERCIAL BUILDING SERVICESFLOW THINKINGAir-conditioning System Components

COMMERCIAL BUILDING SERVICESFLOW THINKINGConstant Volume System Components

FLOW THINKINGCOMMERCIAL BUILDING SERVICESTypical 3-way Valve Zone

FLOW THINKINGCOMMERCIAL BUILDING SERVICESFull Load Condition

FLOW THINKINGCOMMERCIAL BUILDING SERVICESFully Loaded Coil Supply water temperatureDesign return water temp.Coil design flowCoil design pressure dropLoad (flow x 10 F x 500)Coil P @ design flowBypass flowBypass P3-way valve pressure dropPump flow and headActual return water temp45 F55 F100 GPM20 FT500,000 Btuh20 FT0 GPM3-way valve closed10 FT100 GPM @ 30 FT55 F

FLOW THINKINGCOMMERCIAL BUILDING SERVICESUnloaded Condition

FLOW THINKINGCOMMERCIAL BUILDING SERVICESUnloaded Coil Supply water temperatureDesign return water temp.Coil design flowCoil design pressure dropLoad (flow x 10 F x 500)Coil P @ design flowBypass flowBypass P3-way valve pressure dropPump flow and headActual return water temp45 F55 F0 GPM3-way valve closed0.0 Btuh0 FT100 GPM20 FT10 FT100 GPM @ 30 FT45 F

FLOW THINKINGCOMMERCIAL BUILDING SERVICESSo What? When the load on the coil is zero, the valve is returning “unused”chilled water at essentially supply temperature. Cold return water “unloads” the chillers, causing them to operateinefficiently.

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPart Load Condition

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPartially Loaded Coil Supply water temperatureDesign return water temp.Coil design flowCoil design pressure dropLoad (flow x 10 F x 500)Coil P @ design flowBypass flowBypass P3-way valve pressure dropPump flow and headActual return water temp45 F55 F50 GPM20 FT250,000 Btuh5 FT? GPM3-way partially closed10 FT? GPM @ 30 FT? F

FLOW THINKINGCOMMERCIAL BUILDING SERVICES3-way Valve Characteristic1/2 Through Coil1/2 Through Bypass1255025Full FlowThrough Bypass75Full FlowThrough Coil% Flow1000255075100% Valve Stroke

FLOW THINKINGCOMMERCIAL BUILDING SERVICESWhat’s Really Happening?

COMMERCIAL BUILDING SERVICESFLOW THINKINGCoil with 3-way Valve at Mid-position Supply water temperatureDesign return water temp.Load (flow x 10 F x 500)Coil design pressure dropCoil flowCoil P @ 62.5% flowCoil leaving water tempBypass flowBypass P3-way valve pressure dropPump flow and headActual return water temp45 F55 F250,000 Btuh20 FT62.5 GPM7.8 FT53 F62.5 GPM7.8 FT10 FT125 GPM @ 30 FT49 F (62.5 GPM @ 53 F 62.5 GPM @ 45 F)

COMMERCIAL BUILDING SERVICESHead2 Head1(Flow2/ Flow1)2Head2 20(.625/1)2Head2 20(.3906 )Head2 7.8FLOW THINKING

COMMERCIAL BUILDING SERVICESFLOW THINKING T Load/ Flow X 500 T 250,000/62.5 X 500 T 8Therefore, LWTcoil 45 8 53

COMMERCIAL BUILDING SERVICESFLOW THINKINGRWT (Flow1 X EWT Flow2 X LWT)/ Flow1 2RWT (62.5 X 45 62.5 X 53)/125RWT 49

FLOW THINKINGCOMMERCIAL BUILDING SERVICES3-way Valve in Mid Position

COMMERCIAL BUILDING SERVICESFLOW THINKING3-way Valve System Deficiencies1.Low return water temperatures.2.Robs chilled water from other coils at partload conditions.3.Increases flow in primary piping.4.Adds additional chillers on line.5.Chiller performance is reduced.

FLOW THINKINGCOMMERCIAL BUILDING SERVICESChiller Performance Curve1.11.0KW per Ton0.90.80.70.60.510 203040 50 60 70Percent Load80 90 100

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPump Sizing Select for full chiller flow Head must be adequate for:– Chiller evaporator– Longest circuit– Coil– Three way valve– Air separator

FLOW THINKINGCOMMERCIAL BUILDING SERVICESSystem ConfigurationConstant Volume

Any Questions?

Variable Volume Constant Speed

COMMERCIAL BUILDING SERVICESFLOW THINKINGVariable Volume Constant SpeedPrimary – Secondary SystemPrimary –CircuitIncludes Chillers & Primary Pump.Constant water flow through the chilleris maintained and chilled water isproducedSecondary – Chilled water is circulated to theCircuitdemand area (load) by usingSecondary pumps.

COMMERCIAL BUILDING SERVICESPRIMARY - SECONDARYFLOW THINKING

FLOW THINKINGCOMMERCIAL BUILDING SERVICESOther Famous Names of PrimarySecondaryPrimary – Production LoopSecondary – Distribution Loop

FLOW THINKINGCOMMERCIAL BUILDING SERVICESFundamental Idea

FLOW THINKINGCOMMERCIAL BUILDING SERVICESNo Secondary Flow

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPrimary Secondary

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPrimary Secondary

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPrimary Secondary

FLOW THINKINGCOMMERCIAL BUILDING SERVICESControl Valve in Secondary

FLOW THINKINGCOMMERCIAL BUILDING SERVICESCommon Pipe Design Criteria Use the flow of the largest chiller– Chiller staging at half of this flow is common Head loss in common 1 1/2 ft– Distribution pipe size is often used where reductions would beinconvenient Three pipe diameters between tees– Excessive length increases total head loss Low velocities in system piping

FLOW THINKINGCOMMERCIAL BUILDING SERVICESControl Valve in SecondaryVariable flow through coilConstant flow through systemVariable flow through coilVariable flow through systemThree Way ValveTwo Way Valve

COMMERCIAL BUILDING SERVICESFLOW THINKINGVariable Volume Constant SpeedPRIMARY – SECONDARY CIRCUIT

FLOW THINKINGCOMMERCIAL BUILDING SERVICESControl Valves Change the SecondarySystem CurveH1H2H3HeadFlowF1F2F3

FLOW THINKINGCOMMERCIAL BUILDING SERVICESHead Absorbed by 2-way ValvesPump curve150TDH of pump125HD100Varying differential pressureabsorbed by control valve7550System resistance252550% Flow75100

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPump Horsepower Comparison150Constant Flow Primary Pumps, only125HP10075Secondary Pumps 50Primary Pumps V/V25255075% Design Flow100

FLOW THINKINGCOMMERCIAL BUILDING SERVICESConstant vs Variable VolumeC onstant Flow , C /S P um p(3 W ay Valve)150140C /S P um p(2 W ay V alve)130120B aseD esignHP %110P um p H D M atchedto System @D esign FlowC onstant Flow , C /S P um p(3 W ay Valve)100908070C/60% Full Load(D esign) H PP um p O ver-haded by 150%SPumpW(2aylvVae)50403020100102030 4050 60% Flow7080 90100

Any Questions?

Step Function of Chillers

FLOW THINKINGCOMMERCIAL BUILDING SERVICESProduction Distribution

FLOW THINKINGCOMMERCIAL BUILDING SERVICESDistribution Production

COMMERCIAL BUILDING SERVICESFLOW THINKINGProduction Distribution

FLOW THINKINGCOMMERCIAL BUILDING SERVICES“Loading” a Chiller A chiller is a heat transfer device. Like most equipment, it ismost efficient at full load. To “load” a chiller means:– Supply it with its rated flow of water– Insure that water is warm enough to permit removal of rated Btuwithout freezing the water

FLOW THINKINGCOMMERCIAL BUILDING SERVICESChiller Performance Curve1.11.0KW per Ton0.90.80.70.60.510 203040 50 60 70Percent Load80 90 100

FLOW THINKINGCOMMERCIAL BUILDING SERVICESCheck Valve in Common?

FLOW THINKINGCOMMERCIAL BUILDING SERVICESWhat can we do?

FLOW THINKINGCOMMERCIAL BUILDING SERVICESWhat else can we do?Reset Supply Temperature Lower chiller set point when mixing occurs to maintain a constanttemperature to the system. Expect increases in cost of chiller operation at lower set point: 1-3% perdegree of reset. Delays start of the next chiller.

FLOW THINKINGCOMMERCIAL BUILDING SERVICESWhat else can we do? Coils that are selected at higher supply temperatures will not beimpaired by small changes. Loads that require fixed temperatures may use a small chiller toreverse the effects of mixing.

FLOW THINKINGCOMMERCIAL BUILDING SERVICESMultiple Chillers

COMMERCIAL BUILDING SERVICESFLOW THINKING60/40 Chiller Split to Help Minimize Low Part Load Operation

FLOW THINKINGCOMMERCIAL BUILDING SERVICESTypical Load Profile3025% Time201510500-1030-4060-70% Load90-100

FLOW THINKINGCOMMERCIAL BUILDING SERVICESThree Unequally Sized Chillers

FLOW THINKINGCOMMERCIAL BUILDING SERVICESApproaching Flow Load% LoadTime

Any Questions?AlternatePumping MethodsComparison

FLOW THINKINGCOMMERCIAL BUILDING SERVICESTwo Pipe Direct Return

FLOW THINKINGCOMMERCIAL BUILDING SERVICESTwo Pipe Reverse Return

COMMERCIAL BUILDING SERVICESPrimary-Secondary Pumping. Simplest to install.Simplest to operate.Flexible in design for present and future.Efficient to operate. May over-pressurize near zones.FLOW THINKING

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPrimary-Secondary-Tertiary

COMMERCIAL BUILDING SERVICESPrimary-Secondary-Tertiary Pumping. Best piping flexibility.Best expansion flexibility.Provides hydraulic decoupling.Efficient to operate. May require added horsepower. Requires additional pumps and piping. Increased controls complexity.FLOW THINKING

COMMERCIAL BUILDING SERVICESFLOW THINKINGPrimary-Secondary-Tertiary Hybrid

COMMERCIAL BUILDING SERVICESPrimary-Secondary-Tertiary Hybrid Pumping. Low present horsepower.Low future horsepower.Good piping flexibility.Good expansion flexibility.Provides hydraulic decoupling. May require added horsepower Requires additional pumps and piping. Increased controls complexity.FLOW THINKING

COMMERCIAL BUILDING SERVICESFLOW THINKINGPrimary-Secondary Zone Pumping

COMMERCIAL BUILDING SERVICESPrimary-Secondary Zone Pumping. Low ‘built out’ horsepower. Low system head. Increased control complexity.Present horsepower total higher due to future needs.Present pumps sized for future requirements.Difficult to apply in retrofits projects.FLOW THINKING

Any Questions?

Variable Volume Variable Speed

FLOW THINKINGCOMMERCIAL BUILDING SERVICESWhy Do We Need Variable SpeedSecondary Pumps ? For Energy Saving . For better & optimise operation .

COMMERCIAL BUILDING SERVICESFLOW THINKINGHow Do We Achieve This Reduction In PowerConsumption ?By Using Variable Frequency Drive and Logic controllerwith the Secondary Pumps .

COMMERCIAL BUILDING SERVICESFLOW THINKINGPower Comparison at Reduced Speed

COMMERCIAL BUILDING SERVICESFLOW THINKINGBasic Law which helps in achieving this – Affinitylaw1. Flow2 Flow1(Speed2/ Speed1)2. Head2 Head1(Speed2/ Speed1)23. BKW2 BKW1(Speed2/ Speed1)3If Diameter of Impeller is to be trimmed then instead ofspeed the same can be used in above formulas.

FLOW THINKINGCOMMERCIAL BUILDING SERVICESOperating Cost450400Annual Operating Cost 1000350300250 0.10/kWh20015010050050100150200250300350400Motor Horsepower450500

FLOW THINKINGCOMMERCIAL BUILDING SERVICESVariable flow systemPumpCurveSystem Curveas two wayvalves closeHeadSystemCurveFlow

FLOW THINKINGCOMMERCIAL BUILDING SERVICESEnergy savings offsetSystem Curveat part loadPumpCurveIncreasedhead lossHQSystem Curveat design flow

FLOW THINKINGCOMMERCIAL BUILDING SERVICESPumps in parallelSystemCurveHeadSinglePumpFlowPumps inParallel

FLOW THINKINGCOMMERCIAL BUILDING SERVICESParallel pumping power savings100Single Large Pump9080Horsepower 70Two Parallel%Pumps60504030Single Parallel20Pump1000 10 20 30 40 50 60 70 80 90 100Flow%

FLOW THINKINGCOMMERCIAL BUILDING SERVICESTheoretical Savings

FLOW THINKINGCOMMERCIAL BUILDING SERVICESEstablishing Efficiency Curves50 %60 %70 % 80 %85 %% Efficiency85 %80 %100 %Head, Feet90 %% Speed Curves80 %70 %ConstantEfficiencyCurve60 %50%40 %30 %GPM

FLOW THINKINGCOMMERCIAL BUILDING SERVICESVariable Speed Efficiencies4500 gpm @ 100 FT, 85.9 %1150900600A14501770B1770CE1450D1150600750900

FLOW THINKINGCOMMERCIAL BUILDING SERVICES“No Valve” System Curve11025 FT Differential HeadMaintained Across Load(Set Point)Set Point8060Overallsystem curve40Distributionpiping headloss curve20002004006008001000 1200 1400FlowPump TDHHead1001600

FLOW THINKINGCOMMERCIAL BUILDING SERVICESEffect of Constant Set Point11010080Pump TDHHeadSet point,25 FTControl curve60Overall system curve40Distributionpiping headloss curve2000200400600800Flow1000120014001600

FLOW THINKINGCOMMERCIAL BUILDING SERVICESControl s PFlow

FLOW THINKINGCOMMERCIAL BUILDING SERVICESverheadedLarge systems, long pipe ingCost( 1000/year@ 0.10/kwh)O45lgnSi05/SCeOvo,NpmPuingdeahreumpPdeele SpbairaV001000200030004000Total Equivalent Pipe Length(feet)5000