1. TBM thermal modelling status

2. Summary We have 3 models of varying complexity
Plus a GUI version with knobs
All of them applied to a single SAS for comparison
Can be scaled for the whole module
Aim is find optimal point for CV to design their system
cooling topology
dissipated power
water Tin
ambient T
water flow
model
component T
water Tout (total ΔT)
heat to air
Input to CV for dimensioning-costing

3. Model Everything is coupled Mesh size Run time for SAS
Conduction within copper (pipes and the AS), air, water, and the concrete wall
Convection between copper and water; and between copper and air
Radiation exchange between the structure and the walls
Heat loss to the soil outside of the wall is not accounted
Mesh size
~20 million cells
Run time for SAS
~5 hours for convergence

4. Domain 3m 3m 3m water in water out
walls kept at 18 degC for radiation exchange with the AS 3m
air through

5. Output

6. Conclusions Time-consuming
But give more accurate and complete results as everything is coupled
Heat loss to the outside of the tunnel wall may be accounted, but need adequate boundary conditions for modelling the wall and the soil

7. FEA thermal simulations for SAS
ANSYS Thermal steady-state analysis
Single SAS without loads
Run time: ~5min
Heating power 860 W
Cooling water 27 °C, 1.3 l/min
Ambient T = °C
Convection HTC_air = 7.5 W/m^2K
Radiation to surrounding ”space” (T = 18°C)
(no surface-to-surface effect)

8. Water
Radiation
Air convection

9. FEA thermal simulations for TBM
ANSYS Thermal steady-state analysis
T0#2 Module
Run time: ~1hr
Total heating power 7354 W
Cooling water 27 °C, 1.3 l/min
Ambient T = °C
Convection HTC_air = 7.5 W/m^2K
Radiation to surrounding ”space” (T = 18°C)
(no surface-to-surface effect)
Heating power (W) CL
20x
161
3220
PETS 4x 88
352
SAS
860
3440
DBQs 2x
171
342
Total
7354 W

10. Water
Radiation
Air convection

11. Thermal steady-state simulations
Notes:
Steady-state/average heat loads
Static loads (cables etc.) are not taken into account
Convection: Heat transfer coefficients are assumed constant
Radiation:
All of the radiation energy is assumed to be exchanged with the surrounding “space” at constant temperature (18 °C)
What happens to radiated power in reality? How much can the wall absorb? How much ends up heating the air indirectly?
Heating power (W) CL
20x
161
3220
PETS 4x 88
352
SAS
860
3440
DBQs 2x
171
342
Total
7354 W

12. Extra: Results for SAS, when having around 3°C lower component temperature (50% higher water flow, 2 l/min)
Water
~20%
Radiation
~20%
Air convection
3 °C

13. Extra: Module temperature example, T_amb = 30

14. Extra: Module temperature example, SAS+loads cooling channels, T_amb = 30

15. Extra: Module temperature example, SAS core temperatures, T_amb = 30

16. Analytical model Simple pipe, heated and cooled all along
Excludes folding of piping
Run time for SAS: 1 sec
Run time for TBM: 3 sec
Can be used to run many different combinations, including air condition units
flow
Tin
Tout
Dissipated RF power
Heat to air
Heat to water
Radiation

17. Results for SAS

18. Results for TBM Further tuning required
Individual components need to be validated

19. Models summary Alex: Antti: Edmond: VERY simplified Run time ~2sec
Operational
Antti:
FEA with assumptions, still reasonable accuracy
Run time ~1hr for full module
Edmond:
Full CFD, most realistic results
Run time ~3hrs only for a SAS
Needs some polishing
Use this to optimize parameters and topology
Use a combination of those to verify

20. Where to go Wait for next round of measurements with improved sensors
Possible strategy:
Use advanced models for individual components
tune the simple model accordingly