Transcript Document

Application of MULTIFLUX
for air, heat, and moisture
flow simulations
Dr. George Danko, Professor and Davood Bahrami, Research Fellow
Department of Mining Engineering
Mackay School of Earth Sciences and Engineering
College of Science
University of Nevada, Reno
2008 12th US/North American Mine Ventilation Symposium
June 9-11, 2006, Reno, Nevada.
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Goals
• Increase accuracy in predictability of
temperature, humidity, and pollutant
concentration related to safety and health.
• Reduce energy consumption for ventilation and
air cooling
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MULTIFLUX: A coupled, air, heat, and
moisture flow simulation- air contaminant
transport can be added
Heat and moisture
distribution
Air distribution
Pollutant
distribution
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Thermal-Hydrological-Airflow-Contaminant
Modelling with MULTIFLUX
Air flow Model
Selection (THC)
FLUENT
Textbook
Empirical
In-Rock Transport
Model Selection (THC)
MF
CFD
TOUGH
or NUFT
Gibbson’s
Age
Function
Analytical
User’s selection for NTCF surrogate Rock
Model Abstraction model-building Numerical
Transport Code Function alligator
Air Flow and Transport Model Abstraction:
Lumped-parameter CFD model
Coupled Model Solver
Lumped-parameter CFD
DISAC
OUTPUT:
Temperature field
Humidity field
Heat flow field
Moisture flow field
NTCF
MF CFD – Multiflux Computational Fluid dynamics
LLNL – Lawrence Livermore National Laboratory
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NTCF – Numerical Transport Code Functionalization
User
PMHC
(TOUGH2, …)
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PMHC input data for
NTCF model: Tc, T1, T2,
Pc, P1, P2, …
MF5.0
External interface Data preparation (Text editor, utility macro)
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NTCF
input deck
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DISAC
input deck
CFD
input deck
NTCF model
identification
Matrix models for
qh and qm
NTCF
ME
4
T
P
qh
qm
qh
qm
DISAC with Inside Balance
Iteration (IBI)
Coupled results
T, P, qh, qm, qa, qc, qs
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CFD
T
P
qa
qc
qs
Outside Balance
Iteration
(OBI)
Outside Balance Evaluation (OBE):
max|Tc-T|<error limit for T; max|Pc-P|<error limit for P
No
6
Accept
Yes
Document results
Prepare new boundary
conditions from the
balanced results for new
PMHC run
5
6
7
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Rockmass NTCF Matrix Model
NTCF model:
qh = F1(T, P,...)
T,
P,
qh,
qm
qm = F2(T, P, wf,...)
T,
P,
qh,
qm
T, P, qh, qm
F1 , F2 :
T,P
:
qh, qm :
To , Po :
qho, qmo :
hh , hm :
mh , mm :
with wf = f1(T,P,...)
For example:
qh  qho  hh T  To   hm P  Po 
qm  qmo  mh T  To   mm P  Po 
time-invariant, dynamic operators
wall temperature and partial vapor pressure vectors
heat and moisture fluxes
initial values
initial fluxes for To and Po
dynamic admittance matrices for heat flow determined by MULTIFLUX
dynamic admittance matrices for moisture flow determined by MULTIFLUX
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In-drift heat, moisture, and air flow
models: lumped-parameter
Computational Fluid Dynamics (CFD).
qh  F3 T , P , qa,...
qm  F4 T , P , qa,...
qa  F5 T , P, Pb, qh, qm...
F3, F4, and F5 are matrices determined by MULTIFLUX from governing equations:
c
T
t
  cvi
T
x
  ca
 2T
x
2
  ca
 2T
y
2
  ca
 2T
z
2
 qh
 v
 v
 2 v
 2 v
 2 v
 vi
 D 2  D 2  D 2  q cm  q sm
t
x
x
y
z
Pb
 v x

 v  v x   g x 
 Fx

t

x


 v

Pb
  y  v  vy   g y 
 Fy

t

y


Pb
 v

  z  v  v z   g z 
 Fz

t

z



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Mine-wide heat moisture and air
flow model with MULTIFLUX
Pb
Ra
Ra  Raqa
qa 
NTCF NTCF NTCF
NTCF
NTCF NTCF
NTCF
NTCF
NTCF
qh 
Air flow
network model
t
Rh
Heat flow
network model
NTCF NTCF NTCF
NTCF
NTCF NTCF
NTCF
NTCF
NTCF
qm 

Rm
Moisture flow
network model
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Example of heat sources and transport
connections in the proposed underground
nuclear waste repository at YM
(a)
liner
(b)
B
drift wall
L(i)
L(i+1)
Aj(i+1)
Aj(i)
L1(i)
L(i+2)
Aj(i+2)
A5(i)
drip shield
liner
S1(i)
L2(i)
drip shield
A1(i)
A6(i)
W(i)
Aj(i+1)
drift wall
A4(i)
W(i+2)
S2(i)
A2(i)
W(i)
waste
package
A3(i)
pedesta
l
invert
invert
L3(i)
B
Aj : air nodes j=1,2, … 6
W : waste package nodes
air flow
axial dispersion
radiation
heat conduction
L : liner nodes
S : drip shield nodes
Section B-B
NOT TO SCALE
heat convection
controlled convection
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Example – Comparison with CLIMSIM
Plan view and cross sectional view of a 247-m drift segment in the CLIMSIM validation case.
Air intake shaft
rockmass
247 m
dry
surface
Temperature and humidity
measurement Station 2
air
wet
surface
cooling
water
Airflow temperature and humidity
measurement Station 1
Air exhaust
extension
Hydraulic diameter, Dh =2.7333 m
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Example – Heat and Moisture Flow Model
in MULTIFLUX for Comparison with
CLIMSIM
NTCF model
from Gibbson’s
function
Heat
Tdry
Tdry
Tair
Twet
Heat loss
Station 1
Tcooling
water
NTCF model
from Gibbson’s
function
Twet
Tcooling
water
Station 2
13 elements
Moisture
Station 1
P=Psat
P=Psat at surface
temperature
Qm=0 in-role
NTCF model
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Input Data for the Test Case –
Same as in CLIMSIM
Length:
247
m
Cross sectional area:
6.687
m2
Perimeter:
9.786
m
Airway Friction factor:
0.012
kg/m3
Age:
2
Wetness Factor:
0.25
Pressure:
110
Virgin Rock Temperature: (VRT)
48
Thermal Conductivity:
Thermal Diffusivity:
4.82
2.1083e-006
years
kPa
oC
W/moC
m2/s
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Air temperatures and flow tables at drift entrance
same as in CLIMSIM
Air input data at drift intake
Sensible Heat
[ kW ]
Date
Quantity
[ m3/s ]
Dry Bulb
[ oC ]
Wet Bulb
[ oC ]
3/10/1984
3.97
30.8
27.1
-3.14
3/27/1984
3.69
32.2
29
-8.98
4/10/1984
4.05
32.3
28.6
-2.81
4/17/1984
4.56
32.1
28.8
-2.81
4/24/1984
4.25
32.1
28.9
-9.54
5/1/1984
4.25
31.4
28.5
-16.71
5/9/1984
7.38
31.5
28.6
1.07
6/4/1984
5.82
32.4
29
0
6/12/1984
4.16
32.7
29.7
0
6/21/1984
3.79
33
30.2
0
6/26/1984
2.98
33.4
30.7
0
7/3/1984
3.25
34.2
31.3
0
7/10/1984
3.8
33.7
31.3
0
7/26/1984
3.62
33.5
30.8
0
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Measured and simulated air
temperatures at drift exit
Measurements
Date
CLIMSIM prediction
MULTIFLUX
prediction
Dry Bulb
Wet Bulb
Dry Bulb
Wet Bulb
Dry Bulb
Wet Bulb
[oC]
[oC]
[oC]
[oC]
[oC]
[oC]
3/10/1984
33.3
29
33.37
29.01
33.63
28.81
3/27/1984
34.3
30.5
33.93
30.5
34.43
30.35
4/10/1984
34.4
30.3
34.41
30.26
34.51
30.08
4/17/1984
34.2
30.2
34.14
30.29
34.31
30.18
4/24/1984
34.1
30
33.52
30.22
34.19
30.22
5/1/1984
33.2
29.2
32.24
29.63
33.61
29.80
5/9/1984
33.5
29.5
33.12
29.7
33.56
29.86
6/4/1984
34.7
30.4
34.07
30.26
34.31
30.32
6/12/1984
34.4
31.1
35.27
31.29
34.74
30.93
6/21/1984
35.4
31.5
35.81
31.85
35.08
31.37
6/26/1984
35.8
32.1
36.79
32.63
35.56
31.85
7/3/1984
36.5
33
36.99
32.99
36.08
32.41
7/10/1984
36.2
32.7
36.46
32.8
35.71
32.33
7/26/1984
35.5
32.6
36.32
32.43
35.61
31.93
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Root-Mean-Square Error of fit
between models and measurement
RMS error of fit
CLIMSIM
MULTIFLUX
Dry bulb
Temperature ( oC )
0.5874
0.2929
Relative Humidity
(%)
3.5021
1.6718
Root-Mean-Square difference between MULTIFLUX and CLIMSIM modes
RMS difference
Dry bulb Temperature
( oC )
0.7167
Relative Humidity ( % )
2.8280
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Air temperature at drift exit
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Relative humidity at drift exit
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Comparison of total strata heat
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Comparison of sigma heat
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Conclusions
• MF is designed with great flexibility for solving large-scale problems such
as a ventilated underground mine or a high-level nuclear waste repository.
 For example, a 760m-long emplacement drift with hundreds of heat
sources with it, has also been modeled with MF for the proposed
nuclear waste repository at Yucca Mountain
• The software can be used to solve for the coupled (1) thermal, (2)
hydrologic and (3) air flow problems simultaneously.
• All relevant processes of the multi-physics problem are modeled in air
space:
 (1) heat conduction, radiation, convection, latent heat, viscous
dissipation, auto compression for heat;
 (2) moisture convection, diffusion, dispersion, condensation
evaporation for moisture; and
 (3) laminar or turbulent, powered or natural flow for air flow.
• The presented test case shows that MF captures the relevant heat and
moisture transport processes excellently.
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Questions
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