Post on 19-Oct-2015
Chilled Water Distribution System Dynamic Balancing
Ir. Victor LeungProject Director, J. Roger Preston Limited
Chilled Water Distribution System Dynamic Balancing 2
ContentContent
Overview of traditional balancingmechanics, drawbacks & limitations
Chilled water balancing with constant flow valvemechanics and problem
3 in 1 chilled water dynamic balancingtechnical analysis, benefits
Chilled Water Distribution System Dynamic Balancing 3
Traditional Chilled Water Balancing Traditional Chilled Water Balancing & Control& Control
Mechanics Initial balancing with commissioning valves
under full flow condition Maintain index circuit supply/ return pressure
differential at preset level Modulate cooling coil chilled water control valve
opening to regulate chilled water flow rate maintain preset indoor space temperature
Chilled Water Distribution System Dynamic Balancing 4
Traditional Chilled Water BalancingTraditional Chilled Water Balancing
Mechanics Initial balancing with commissioning
valve under full flow condition Require comprehensive chilled
water distribution circuit hydraulics analysis to determine initial commissioning valve setting & refinement / adjustment with on site measurement
Problems Laborious process to determine
valve setting Prone to improper and incomplete
commissioning Initial static balancing under full flow
condition will distorted under dynamic condition
Chilled Water Distribution System Dynamic Balancing 5
Traditional Chilled Water ControlTraditional Chilled Water Control
Mechanics Modulate chilled water control valve opening to
regulate chilled water flow rate & maintain preset indoor space temperature
Problems Space temperature controller can only modulate the
control valve opening, its effect on chilled water flow rate is unknown
Relatively high initial resistance due to necessary 50% control valve authority (ie full open control valve resistance = cooling coil + commissioning valve resistance)
Chilled Water Distribution System Dynamic Balancing 6
% of Design Flow
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Coil
DRV
0% 100%
HydronicHydronic FundamentalsFundamentalsTraditional control valve and Double Regulating ValveTraditional control valve and Double Regulating Valve(index circuit)(index circuit)
Chilled Water Distribution System Dynamic Balancing 7
% of Design Flow
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Coil
DRV
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Coil + DRV
HydronicHydronic FundamentalsFundamentalsTraditional control valve and double regulating valveTraditional control valve and double regulating valve(index circuit)(index circuit)
Chilled Water Distribution System Dynamic Balancing 8
% of Design Flow
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Control Valve
Coil
DRV
0% 100%
Coil + DRV
HydronicHydronic FundamentalsFundamentalsTraditional control valve and double regulating valveTraditional control valve and double regulating valve(index circuit)(index circuit)
Chilled Water Distribution System Dynamic Balancing 9
% of Design Flow
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Control Valve
Coil
DRV
0% 100%
Coil + DRV
HydronicHydronic FundamentalsFundamentalsTraditional control valve and double regulating valve Traditional control valve and double regulating valve (index circuit)(index circuit)
Index circuit Total pressure drop
Index circuit Total pressure drop
Chilled Water Distribution System Dynamic Balancing 10
Chilled Water Balancing with Chilled Water Balancing with Constant Flow ValveConstant Flow Valve
Mechanics Constant Flow Valves limit chilled water flow rate to below presetProblems Only serves to limit flow rate and do not have system resistance
balancing function as for commissioning valve since pressure drop across valve remains relatively constant at below preset flow rate
Introduces noticeable resistance to distribution system as valve balancing action depends on pressure loss across valve
Chilled Water Distribution System Dynamic Balancing 11
33--inin--1 Chilled Water Dynamic Balancing1 Chilled Water Dynamic BalancingMechanics Combine commissioning/ automatic
balancing/ control valve functions into one
Deliver exact chilled water flow rate as determined by space temperature controller
Benefits System initial balancing much
simplified Improves indoor condition with
more direct control of chilled water flow rate
Minimizes system chilled water flow resistance
Orifice controlled
by actuator
Orifice self-adjusted by
system pressure
Chilled Water Distribution System Dynamic Balancing 12
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CoilDynamic Balancing Control valve
% of Design Flow0% 100%
HydronicHydronic FundamentalsFundamentalsDynamic BalancingDynamic Balancing
Coil
Chilled Water Distribution System Dynamic Balancing 13
P
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CoilDynamic Balancing Control valve
% of Design Flow0% 100%
HydronicHydronic FundamentalsFundamentalsDynamic BalancingDynamic Balancing
Coil
Total Pressure drop
Chilled Water Distribution System Dynamic Balancing 14
Advanced TechnicalAnalysis
Advanced TechnicalAnalysis
Chilled Water Distribution System Dynamic Balancing 15
33--inin--1 Chilled Water Dynamic 1 Chilled Water Dynamic Balancing Balancing Static ConditionStatic Condition
Under conditions of all parameters including
P1, P3 and k1, k2, & K being fixed
From (4), P2 varies only with A1From (3), Q varies only with A1Note (*) The linearity of Q in equations (1) and (2) depends on manufacturer design and construction tolerance
A2, k2A1, k1
2111 PPAkQ 3222 PPAkQ
3231
2 PPPPKkQ
..(1*)
..(2*)
..(3)
Where k1 & k2 are flow coefficients, and K is relation of A2 to(P1-P3 ), From (1) and (3), we have
3231
22111 PPPPK
kPPAk = ..(4)
Chilled Water Distribution System Dynamic Balancing 16
33--inin--1 Chilled Water Dynamic 1 Chilled Water Dynamic Balancing Balancing Dynamic ConditionDynamic Condition
Flow rate remain constant with system pressure variation
31 PP 21 PP 32 PP
322 PPAQ 31
2 PPKA
A2, k2A1, k1 ( - ) no change
therefore, no change
....
....
..
..
Chilled Water Distribution System Dynamic Balancing 17
What are theTechnical Advantages?
What are theTechnical Advantages?
Commissioning
System Performance
Energy Efficiency
Chilled Water Distribution System Dynamic Balancing 18
Commissioning Performance Energy
Easy Commissioning
Chilled Water Distribution System Dynamic Balancing 19
Preset of Maximum FlowPreset of Maximum Flow
Valve can be conveniently preset for maximum flow by local adjustment or remote via BMS
Max. flow setting in actuator
Max. flow setting by BMS
Chilled Water Distribution System Dynamic Balancing 20
Commissioning Performance Energy
Pressure Independent Control
Chilled Water Distribution System Dynamic Balancing 21
Pressure Independent CharacteristicPressure Independent Characteristic
Flow can be conveniently preset and then maintained constant under dynamic condition with minimum required pressure differential
Accurate control of flow rate over larger control range as compared with traditional control valve
Valve max. flow
Pre-setDesignFlow
50% 6V
max kPamin kPadiff pressure
0 2V
Control SignalDesign flow
Preset
10V100%
Chilled Water Distribution System Dynamic Balancing 22
Commissioning Performance Energy
Good Space Temperature Control
Chilled Water Distribution System Dynamic Balancing 23
Steady Space Temperature being maintainedSteady Space Temperature being maintained
18
20
22
24
26
28
30
6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00
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Time
With air conditioningWith air conditioning
Chilled Water Distribution System Dynamic Balancing 24
Commissioning Performance Energy
Linear Control on Flow Rate
Chilled Water Distribution System Dynamic Balancing 25
Linear Control of Flow RateLinear Control of Flow Rate
0.00
3.60
7.20
10.80
14.40
2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10
Control signal (V)
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Testresult
DirectDirect and linearlinear relationship of control signal with and flow rate over noticeable large control range as compared with traditional control valve
Chilled Water Distribution System Dynamic Balancing 26
Commissioning Performance Energy
Energy Saving
Chilled Water Distribution System Dynamic Balancing 27
% of Design Flow
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Control Valve
Coil
DRV
0% 100%
Coil + DRV
HydronicHydronic FundamentalsFundamentalsTraditional control valve and double regulating valveTraditional control valve and double regulating valve(index circuit)(index circuit)
Index circuitTotal pressure drop
Index circuitTotal pressure drop
Chilled Water Distribution System Dynamic Balancing 28
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CoilDynamic Balancing Control valve
% of Design Flow0% 100%
HydronicHydronic FundamentalsFundamentalsDynamic BalancingDynamic Balancing
Coil
Total Pressure drop
Chilled Water Distribution System Dynamic Balancing 29
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% of Design Flow0% 100%
Energy Saving Energy Saving in Dynamic Balancing systemin Dynamic Balancing system
System with Traditional Control valve & Double
Regulating Valve
System with Dynamic Balancing
Control Valve
Energy saved
160
95 kPa
50
160 kPa
Chilled Water Distribution System Dynamic Balancing 30
Commissioning Performance Energy
Flowrate monitoring
Chilled Water Distribution System Dynamic Balancing 31
Flow MonitoringFlow MonitoringComparison with Electromagnetic Type Flowmeter
No specific requirementMin 5D upstream & 3D downstream to ensure accurate measurement
Installation requirement
Up to 35kPa for valve max. flow rate @ 2m/s
No requirementDiff pressure
Independent of installation.
2% of valve maximum flow rate at 2m/s
Highly depend on compliance of installation requirement.Typical catalogue quoted accuracy: 0.5% of operating range (flowmeter design at 9 to 10m/s).Accuracy @ pipe actual flow rate of 2m/s:1.8 -2.25%
Accuracy
Determine the flow rate by calibrated opening (orifices)
Determine the fluid velocity by induced voltage
Mechanics
3-in-1 Dynamic Balancing Control Valve
Flowmeter(electromagnetic type)
Chilled Water Distribution System Dynamic Balancing 32
Case Study : Case Study :
Flowrate feedback by the Dynamic Balancing Control valve and monitored by the BMS system
Office Tower in Office Tower in SingaporeSingapore
Chilled Water Distribution System Dynamic Balancing 33
AHU3
AHU2
AHU1
Chiller1
Chiller2
Chiller3
DCV
CFV3
CFV2
CFV1
FMb
DCV
DCV
qS1
qS2
qS3
qD1
qD2
qD3
QbQS
QD
BPV
AHUn DCVqDn
FMQ
DCV Dynamic balancing control valve CFV Constant flow valve BPV By-pass Valve
bFM Flowmeter to measure bypass flow QFM Flowmeter to verify flow in riser
iqD Air Handling Unit demand flow
determined from Dynamic balancingcontrol valve feedback signal
DQ Total system demand flow
= nqDqDqDqD ++++ 321
jqS Supply flow of each chiller
SQ Total plant supply flow = 321 qSqSqS ++
bQ Bypass flow, DS QQ Pumps and isolation valves not shown
Schematic of the Schematic of the HydronicHydronic SystemSystem
Chilled Water Distribution System Dynamic Balancing 34
Flow Rate VerificationFlow Rate VerificationResults
QD, Required demand calculated via feedback signal of DCV (3-in-1 dynamic balancing control valves) = qD1 + qD2 + qD3 +. qDn= 27.44 Lps
FMQ, flow rate measured in supply mains by flowmeter= 27.38 Lps
Only minor variance between summation of DCV valve and flowmeter measurement
AHU3
AHU2
AHU1
Chiller1
Chiller2
Chiller3
DCV
CFV3
CFV2
CFV1
FMb
DCV
DCV
qS1
qS2
qS3
qD1
qD2
qD3
QbQS
QD
BPV
AHUn DCVqDn
FMQ
Chilled Water Distribution System Dynamic Balancing 35
SummarySummary
Chilled Water Distribution System Dynamic Balancing 36
Chilled Water Distribution System Dynamic BalancingChilled Water Distribution System Dynamic BalancingSummarySummary
Deliver exact flow rate under dynamic condition as required by space temperature controller
Only limit flow rate and do not have balancing function
Only achieve balancing under full load static condition which becomes distorted under dynamic condition which resistance of system components changes
Mechanics
Dynamic system: 3-in-1 Dynamic Balancing Control valve
Constant Flow valve in series with Control valve
Traditional system: Balancing valve in series with Control valve
Chilled Water Distribution System Dynamic Balancing 37
Convenient preset of maximum flow either locally at the valve or remotely at BMS
No commissioning required
Require laborious hydraulic analysis to determine appropriate valve setting, adjustment of valve setting has to be performed and verified locally at the valve which is prone to error
Commissioning
Dynamic system: 3-in-1 Dynamic Balancing Control valve
Constant Flow valve in series with Control valve
Traditional system: Balancing valve in series with Control valve
Chilled Water Distribution System Dynamic BalancingChilled Water Distribution System Dynamic BalancingSummary (conSummary (cont)t)
Chilled Water Distribution System Dynamic Balancing 38
Yes. NilNilFlow rate monitoring
Energy saving due to low initial full load control valve pressure loss and ability to capture reduced system resistance at partial load
Same as the case of Traditional system of balancing valve in series with control valve but with additional energy consumption due to balancing valve resistance
Waste energy due to high initial full load control valve pressure loss and inability to capture reduced system resistance at partial load
Energy efficiency
Dynamic system: 3-in-1 dynamic balancing control valve
Constant flow valve in series with control valve
Traditional system: balancing valve in series with control valve
Chilled Water Distribution System Dynamic BalancingChilled Water Distribution System Dynamic BalancingSummary (conSummary (cont)t)
Chilled Water Distribution System Dynamic Balancing 39
Superior control performance due to direct relationship of space temperature control signal to chilled water flow rate and satisfactory modulating capability under partial load condition
Do not have system resistance balancing function and hence performance is inferior to traditional commissioning valve
Indirect relationship of space temperature control signal to chilled water flow rate and inferior modulating capability under partial load condition
System Performance
Dynamic system: 3-in-1 Dynamic Balancing Control valve
Constant Flow valve in series with Control valve
Traditional system: Balancing valve in series with Control valve
Chilled Water Distribution System Dynamic BalancingChilled Water Distribution System Dynamic BalancingSummary (conSummary (cont)t)
Chilled Water Distribution System Dynamic Balancing 40
Thank You!Question and Answer
Thank You!Question and Answer