CFD model setup & boundary conditions

1. PSB Dump air coolingResults with:1. Flat dump without fins 2. Fins ‘5 mm – 10 mm – 10 mm’ 3. Fins ‘5 mm – 10 mm – 20 mm’4. Fins ‘5 mm – 25 mm – 20 mm’5. Fins ‘5 mm – 25 mm – 50 mm’ E. Da Riva, M. Gomez Marzoa

2. Contents1. Set-up and geometry2. Pressure drop with “smooth” and “sharp” connection3. Temperature results with different fins geometries4. Some detailed results E. Da Riva, M. Gomez Marzoa

3. CFD model setup & boundary conditions • Air flow and heat transfer in the fluid and solid solved all together in a single simulation. • Steady-state simulation. • Turbulence model : Standard k-ε +standard wall functions. • Gravity and buoyancy taken into account (even if not really relevant in this case). • Dependence of air conductivity, viscosity and constant heat on temperature taken into account. • Thermal conductivity of copper C18150: 320 W m-1 K-1 (temperature independent). • Inlet flow rate: 1800 m3 h-1 (→ 15 K air temperature rise, 12.5 m/s air velocity in the ducts). • Air injected from the ducts. • Air temperature at inlet: 20 °C. • Energy deposition inside the dump: imported from FLUKA file (~9500 W). E. Da Riva, M. Gomez Marzoa

4. CFD model: geometry PSB Dump Beam pipe Air duct Full geometry: symmetry applied in the model 8 L min-1, 0.5 W cm-2 PSB Dump Beam pipe Beam pipe separated 1 cm from dump. E. Da Riva, M. Gomez Marzoa

5. 2 geometries considered in the CFD simulations: Duct connection geometry “smooth connection” B. “sharp connection” • 159 mm i.d. for both duct & connection Actual geometry from CATIA model: PSB Dump • ~160 mm i.d. for the duct • ~150 mm i.d. for the connection • Inner surface of the duct end rounded • 150 mm internal diameter • 150 mm bending radius E. Da Riva, M. Gomez Marzoa

6. Pressure drop results “Smooth connection” B. “Sharp connection” Gauge pressure at 1800 m3h-1[Pa]. E. Da Riva, M. Gomez Marzoa

7. Energy deposition Energy deposition in the dump [W m-3]. • Heat generation inside the dump imported from FLUKA file: ~9450 W total power. E. Da Riva, M. Gomez Marzoa

8. The solution of “thin fins” brazed on the dump is neglected because of manufacturing consideration. • Only “bulky fins” machined on the dump cylinder are taken into considerations • Diameter of dump: 400 mm at the foot of the fins. • 3 different dump surfaces simulated: Fins geometry r = 220 mm r = 200 mm ‘5-10-10’ fins. ‘5-10-20’ fins. ‘5-25-20’ fins. ‘5-25-50’ fins. E. Da Riva, M. Gomez Marzoa

9. Temperature at the symmetry plane [°C]. CFD results: temperature B. ‘5-10-10’ fins A. ‘no fins’ C. ‘5-10-20’ fins D. ‘5-25-20’ fins E. ‘5-25-50’ fins E. Da Riva, M. Gomez Marzoa

10. Detailed results for ‘5-10-20’ fins(aka ‘didactic fancy pictures’) E. Da Riva, M. Gomez Marzoa

11. Velocity (5-10-20 fins, 1800 m3h-1) Velocity at the symmetry plane [m s-1]. E. Da Riva, M. Gomez Marzoa

12. Temperature (5-10-20 fins, 1800 m3h-1) Temperature [°C] at 0.5 m from the front (hot) end of the dump. • Note that the air flowing between the fins is locally much warmer than the average out air temperature (35°C) → important to take into account the dependency of air properties on temperature. • Homogeneous temperature of fins → no problem of thermal fins efficiency (on copper side). E. Da Riva, M. Gomez Marzoa

13. Temperature (5-25-20 fins, 1800 m3h-1) Temperature [°C] at 0.5 m from the front (hot) end of the dump. E. Da Riva, M. Gomez Marzoa

14. Temperature (5-25-50 fins, 1800 m3h-1) Temperature [°C] at 0.5 m from the front (hot) end of the dump. E. Da Riva, M. Gomez Marzoa

15. Velocity (5-10-20 fins, 1800 m3h-1) • The area available for the air flow between the dump (D=400 mm at the foot of fins) and the shielding (D=500 mm) is extremely important since it determines the air velocity and therefore the heat transfer coefficient. • Note that the air velocity in the gap between 2 fins is smaller than far away from the fins → the local heat transfer coefficient is reduced. E. Da Riva, M. Gomez Marzoa

16. Velocity (5-25-20 fins, 1800 m3h-1) • Increasing the gap between the fins, a more favorable velocity is locally achieved, however the total surface available for the heat transfer is reduced. • The geometry ‘5-25-20’ performs better than ‘5-10-10’ (168°Cvs188°C, same total area available). • The geometry ‘5-10-20’ performs better than ‘5-25-20’ (150°Cvs168°C) because the highertotal area availableis the dominating effect. E. Da Riva, M. Gomez Marzoa

17. Velocity (5-25-50 fins, 1800 m3h-1) • The area available for the air flow between the dump (D=400 mm at the foot of fins) and the shielding (D=500 mm) consists in closed ducts and the air flow is better exploited. • The ducts on the top display a higher velocity. E. Da Riva, M. Gomez Marzoa

18. Heat flux (5-10-20 fins, 1800 m3h-1) Local heat flux [W m-2]. • The highest heat flux is achieved at the top of the fins. • The surface at the foot of fins is not ideally exploited because of the local reduced air velocity. E. Da Riva, M. Gomez Marzoa

19. Heat flux (5-25-20 fins, 1800 m3h-1) Local heat flux [W m-2]. E. Da Riva, M. Gomez Marzoa

20. Heat flux (5-25-50 fins, 1800 m3h-1) Local heat flux [W m-2]. E. Da Riva, M. Gomez Marzoa