1. Undulator Hall Power Dissipation
What is it and where does the heat go?
January 22, 2008
Undulator System Meeting

2. Contents Air Flow Average heating Localized heating January 22, 2008
Undulator System Meeting

3. Air Flow From West to East only Constant flow rate 20,000 cfm
air is recirculated and brought back through a large duct in the Undulator Hall to the West end
same direction as beam
Constant flow rate 20,000 cfm
Low average velocity, ≈ 1 mph
January 22, 2008
Undulator System Meeting

4. January 22, 2008
Undulator System Meeting

5. Flow Characteristics
Turbulent Flow --- Reynolds number for tunnel cross-section ( FH= 21.5 ft) is 180,000.
Low velocity --- ≈ 1 mph.
January 22, 2008
Undulator System Meeting

6. Temperature Control Only one zone for temperature control
just one temperature variable can be adjusted
Temperature control
Input temperature at discharge into the Undulator Hall will be held within ± 1 F at 68 F, with “Process Heat Load” up to 8.5 kW.
The “Process Heat Load” is from the present and future undulator system equipment and doesn’t include lighting or environmental heating/cooling sources.
Note 8.5 kW is 50 W/m of tunnel and 65 W/m of undulator line
January 22, 2008
Undulator System Meeting

7. Sources of Heating/Cooling
Access
People, equipment brought in, leakage of air
Undulator System
See next slide
Tunnel walls and floor
Initial warm up, seasonal variations, moisture
Utilities
Lighting, exit signs, power lines, chilled and hot water lines, phone/data/fire/pps
Other systems
DL2/Vertical Bend magnet wires
Many different time scales: quasi-static to random
January 22, 2008
Undulator System Meeting

8. Undulator System Heating Loads
F.O. Radiation Loss System
Photodiode Radiation Loss System
Camera Motors
Cameras
Quad magnets
Corrector magnets
Quad and Corrector Wires
BPM RF Receivers
BFM Sensor electronics
HLS
WPM
Cable Drops
MPS Link Boxes
Vacuum Pumps
Magnet Water Lines Convective load
Quad Power Lines
UCM Rack and Contents
Translation Motors
CAM Motors
Undulator Motion IOC
Diagnostic Motors
Diagnostic Motor IOC
Photomultiplier
Current Estimate for Total Undulator System Load
11 kW (85 W/m of undulator line)
January 22, 2008
Undulator System Meeting

9. Estimated Temperature Profile
Total temperature rise of 1.0 deg C
The temperature rise will increase with time as the tunnel warms up and additional heat loads are added.
Probably want to offset discharge temperature 1 F to get mean at 68 F.
WEST
EAST
January 22, 2008
Undulator System Meeting

10. Localized Heating
Warm air from local heat sources will completely mix with tunnel air within a few (<10) tunnel diameters
Locally heated air persists in boundary layers which grow in size and mix with the main tunnel air stream.
January 22, 2008
Undulator System Meeting

11. Forced Air Flow Around Racks or Pedestals
Laminar layer forms around obstacle, eddies form downstream of it.
ReD for support pedestals is about 30,000 so it will have same type of flow
From Kreith, pg 406
January 22, 2008
Undulator System Meeting

12. Free Convection Air Flow Around Racks
warmed air forms a thin boundary layer next to rack and rises
air velocity at top of rack ~2 ft per s
January 22, 2008
Undulator System Meeting

13. Localized Heating Estimate
4-5 deg C air rises from the rack sides, more or less vertically, and warms a portion of the grider and segment
Heat flows through the girder and segment and back into the air.
January 22, 2008
Undulator System Meeting

14. Temperature averaging
Effects of short term air temperature changes can be significantly averaged out.
Example: Undulator segment
Measured response time constant  ≈ 16 hrs. For temperature changes at period of 24 hr,  = 0.26 hr-1, there is about a factor of 4 reduction in the response of the undulator temperature.
January 22, 2008
Undulator System Meeting

15. Conclusions
Tunnel air temperature will rise by 1 deg C or more along the tunnel length due to power dissipation
Undulator system is the dominate heat source
Localized heating was semi-quantitatively investigated
150 W racks placed under the segmentswill warm adjacent air 3-4 deg C
Warmed air will rise and flow directly onto the girder and undulator segment
January 22, 2008
Undulator System Meeting