Dynamic Modeling of Two-Phase Helium Pipe Flow in the Cryosystem at the Canadian Light Source
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Dynamic Modeling of Dynamic Modeling of Two-Phase Helium Pipe Two-Phase Helium Pipe Flow in the Cryosystem Flow in the Cryosystem at the Canadian Light at the Canadian Light Source Source Chris Regier, Ph.D. Candidate Chris Regier, Ph.D. Candidate University of Calgary University of Calgary Schulich School of Engineering Schulich School of Engineering Dept. of Mechanical and Manufacturing Engineering Dept. of Mechanical and Manufacturing Engineering Calgary, Alberta, Canada Calgary, Alberta, Canada June 11, 2008 June 11, 2008
description
Dynamic Modeling of Two-Phase Helium Pipe Flow in the Cryosystem at the Canadian Light Source. Chris Regier, Ph.D. Candidate University of Calgary Schulich School of Engineering Dept. of Mechanical and Manufacturing Engineering Calgary, Alberta, Canada June 11, 2008. Overview. - PowerPoint PPT Presentation
Transcript of Dynamic Modeling of Two-Phase Helium Pipe Flow in the Cryosystem at the Canadian Light Source
Dynamic Modeling of Two-Dynamic Modeling of Two-Phase Helium Pipe Flow in the Phase Helium Pipe Flow in the Cryosystem at the Canadian Cryosystem at the Canadian
Light SourceLight SourceChris Regier, Ph.D. CandidateChris Regier, Ph.D. Candidate
University of CalgaryUniversity of CalgarySchulich School of EngineeringSchulich School of Engineering
Dept. of Mechanical and Manufacturing EngineeringDept. of Mechanical and Manufacturing Engineering
Calgary, Alberta, CanadaCalgary, Alberta, Canada
June 11, 2008June 11, 2008
OverviewOverview
The CLS and the RF Cavity The CLS and the RF Cavity
The Cryogenic SystemThe Cryogenic System
The Liquid Helium (LHe) Supply LineThe Liquid Helium (LHe) Supply Line
Modeling and Simulation ProcedureModeling and Simulation Procedure
ResultsResults
The CLS and the RF CavityThe CLS and the RF Cavity
RF CavityRF Cavity500 MHz VHF500 MHz VHFReplenishes lost Replenishes lost electron beam electron beam energyenergySuperconducting Superconducting Operates ~ 4.5 KOperates ~ 4.5 KRequires LHe Requires LHe Cryogenic systemCryogenic system
The Cryogenic SystemThe Cryogenic System
LHe Transfer Line
The Cryogenic SystemThe Cryogenic SystemComputer Model of entire cryo system desiredComputer Model of entire cryo system desired Dynamic system model – Controls perspectiveDynamic system model – Controls perspective Can answer questions about system operationCan answer questions about system operation Model individual components and connectModel individual components and connect
The LHe Supply LineThe LHe Supply Line
The LHe Supply LineThe LHe Supply Line
LHe Line is one component of the systemLHe Line is one component of the system Possibly most complex modelPossibly most complex model
LHe Line Exhibits Two-Phase FlowLHe Line Exhibits Two-Phase Flow Much more difficult to simulateMuch more difficult to simulate May be required to create effective dynamic May be required to create effective dynamic
modelmodel Flow boiling due to:Flow boiling due to:
Temperature increaseTemperature increase
Pressure decrease causes majority of boilingPressure decrease causes majority of boiling
Modeling and SimulationModeling and Simulation
ObjectivesObjectives of LHe Supply Line Simulation: of LHe Supply Line Simulation:
1.1. Ability to simulate liquid and gas flowrates Ability to simulate liquid and gas flowrates exiting the LHe lineexiting the LHe line
3.3. Determine whether a simpler model can Determine whether a simpler model can produce accurate resultsproduce accurate results
Quasi-Steady-State?Quasi-Steady-State?
Simple dynamic model? Simple dynamic model?
2.2. Determine whether gas has impact on flowDetermine whether gas has impact on flow
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Modeling and SimulationModeling and Simulation
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x
v
t
bgggg Q
x
v
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x
P
x
v
t
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Two-Phase Flow ModelingTwo-Phase Flow Modeling
Mass of GasMass of Gas
Mass of LiquidMass of Liquid
MomentumMomentum
EnergyEnergy
1-D Conservation equations1-D Conservation equations
x
PvvFQ
x
ev
t
ef
Modeling and SimulationModeling and SimulationDiscretize conservation equations Discretize conservation equations
Use upwind scheme to solveUse upwind scheme to solve Solution depends only on upstream propertiesSolution depends only on upstream properties Can start at inlet of line and solve each grid Can start at inlet of line and solve each grid
cell in sequence to end of line.cell in sequence to end of line.
Cell j Cell j+1
Pj, gj, vj, TjPj+1, gj+1, vj+1, Tj+1
Modeling and SimulationModeling and SimulationBCs complicate solutionBCs complicate solution LHe line inlet velocity not knownLHe line inlet velocity not known Outlet pressure known insteadOutlet pressure known instead
1. Guess inlet velocity1. Guess inlet velocity
2. Solve P, v, 2. Solve P, v, gg, T for each cell along pipe, T for each cell along pipe
3. If outlet P is correct then go to next time 3. If outlet P is correct then go to next time stepstep
4. If outlet P is not correct then adjust guess 4. If outlet P is not correct then adjust guess of inlet v and repeatof inlet v and repeat
Modeling and SimulationModeling and SimulationTo solve P, v, To solve P, v, gg, T for a grid cell , T for a grid cell Solution of each equation depends on all 4Solution of each equation depends on all 4
Set state ij = state i-1 j
Solve Energy Cons.
Solve Gas Mass Cons. g ij
Solve Liq Mass Cons.vij
Solve Momentum Cons. Pij
Is delta Pij, ag ij, vij and Tij small enough?
Set Tij to boiling T Tij = 0.232Pij
0.252
No YesIs g ij > 0?(Is there 2-phase
flow?)
Solve Liquid Mass Cons.
vij = vij-1
Solve Momentum Cons.
Pij
Solve Energy Cons. Tij
Is Tij > Tb ij?(Is there 2-phase
flow?)
Solve boiling temp Tb ij = 0.232Pij
0.252
No
No
Yes
Yes
Start
End
ijbQ
ResultsResultsObjectiveObjective 11: Ability to simulate various flows: Ability to simulate various flows RR22 value = 0.91 value = 0.91
Based on measured rates at CLSBased on measured rates at CLS Simulated various valve positions & heat loadsSimulated various valve positions & heat loads
Average error 6.3%Average error 6.3%
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0 5 10 15 20 25 30Valve opening (%)
Lh
e F
low
rate
(L
/s)
Experimental
Simulated
ResultsResultsObjectiveObjective 22: Determine if gas impacts flow : Determine if gas impacts flow Maximum Maximum gg ~0.12 at pipe exit ~0.12 at pipe exit gg varies slightly with control valve position varies slightly with control valve position Some impact on flow of LHeSome impact on flow of LHe
0.00
0.05
0.10
0.15
0.20
0.25
0% 10% 20% 30% 40% 50%
Valve Position
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rac
tio
n G
as
at
Ex
it
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Mas
s F
low
(g
/s)
Void Fraction Gas:1.21 barVoid Fraction Gas:1.00 barLHe Mass Flow:1.21 BarLHe Mass Flow:1.00 bar
ResultsResultsObjectiveObjective 33: Can a simpler model be used?: Can a simpler model be used? Quasi-steady-state has problemsQuasi-steady-state has problems
gg dynamics are very slow dynamics are very slow
QSS can incorrectly predict oscillation size and phaseQSS can incorrectly predict oscillation size and phase
ResultsResultsObjectiveObjective 33: Determine if a simpler model : Determine if a simpler model can be usedcan be used
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AcknowledgementsAcknowledgementsJ. Pieper – U of CJ. Pieper – U of C
Elder Matias - CLSElder Matias - CLS
Mark deJong – CLSMark deJong – CLS
Mark Silzer – CLSMark Silzer – CLS
Jon Stampe - CLSJon Stampe - CLS
Abdulmajeed Mohammad – U of CAbdulmajeed Mohammad – U of C
John Swirsky - CLSJohn Swirsky - CLS
J. Bugg – U of SJ. Bugg – U of S
Carey Simonson – U of SCarey Simonson – U of S
Tom Regier - CLSTom Regier - CLS
