Cooling Update(May 2011)

Tim

Cooling Update 2

Overview• From last time– Estimate Power Loads• Active components• Extraneous heat sources

– Develop methodology for exploring cooling system parameter space• Flow rate• Pressure drop• Pipe bores

• Control and Monitoring– Strategies– Implementation

15/03/2011

Cooling Update 3

Power Estimate• FE

– 32 PMTs per array– 4 arrays per cooling circuit connected in series– 0.5W per PMT– 16W per PMT array, 64W for four arrays on one side

• Environment– Box dimensions 1.2(h) x 0.6(w) x 0.3(d).

• Area of 5 sides = 2.16sq.m

– Box insulation k=0.05 W.m-1.K-1

– Wall thickness 50mm– Assume external wall is at 40C and internal wall is at 20C– Power = 0.05 x 2.16 x 20 / 0.05 = 47W

• Total Power– 64 (FE) + 47(env) = 107W

15/03/2011

Cooling Update 4

Pipe-work Geometry• External Interconnect– Flow and return lines 7m long with a bore of

12mm

• Internal– Heat exchanger: heated length 0.5m per array– Interconnect: 4m in total– Bore: 4, 6, 8mm

15/03/2011

Cooling Update 5

Draft Chiller Requirements

T rise 0.5deg C 0.25deg C 0.10 deg C

Bore 4mm 6mm 8mm 4mm 6mm 8mm 4mm 6mm 8mm

Flow 3.09 3.09 3.09 6.17 6.17 6.17 15.43 15.43 15.43

Pressure 3.52 0.55 0.17 11.8 1.83 0.57 58.8 9.13 2.83

• Tabulate Flow and pressure for different bores of the internal pipe work and desired temperature rise

• Chiller Specifications (preliminary web-trawl)

Model Power Flow (lpm @ 0 bar) Pressure (bar)Fryka DLK 402 380W @ 30C 4 0.15Grant RC350G 350W @ 20C 15 1.60 (@1 lpm)Neslab Thermoflex 900/P2 900W @ 40C 12.5 (@4.1 bar) 7 barJubalo FC600S 600W @ 20C 15 1.2Cole-parmer WU-13042-07 250W @ 20C 21 0.8Lauda WK 502 600W @ 20C 10 (@1.5bar) 2.2

15/03/2011

Cooling Update 6

Control• Issues

– Maintain the PMT arrays at a given temperature– Control the heat transfer between the box and the CEDAR

• Options1. Control the PMT array temperatures such that the global temperature of the

box is close to the CEDAR. Provide sufficient thermal insulation to minimise coupling between box and CEDAR.

2. Monitor the CEDAR temperature and control the temperature of the PMT arrays such that the temperature difference between the box and the CEDAR is minimised.

3. Control the PMT array temperatures such that the global temperature of the box is just below the CEDAR. Provide an ACTIVE thermal enclosure between the box and the CEDAR and control the temperature on the CEDAR side to minimise heat flow.

• Need more engineering input to define interfaces between CEDAR and box15/03/2011

Cooling Update 7

Option 1

15/03/2011

Cooling Update 8

Comments• Option 1:

– Likely to need greatest number of interventions to adjust chiller PID controller

– Needs chiller with in-built heater– Needs high precision chiller set-point & stability

• Option 2:– Highest cooling power requirement– Need to develop fault tolerant PLC /heater sub-system

• Option 3:– Chiller may not need in-built heater– May allow low precision chiller set-point & stability– Complete segmentation of control sub-systems– Needs detailed engineering analysis / design & manufacture of active

thermal enclosure15/03/2011

Cooling Update 9

Chiller Issues• Issues

– Radiation field• What’s the annual dose ?• What’s the chiller operational lifetime?

– Condenser motor, water pump– PID controller– Fittings, gaskets, seals …

– Explosion• Chiller located ~ 7m from CEDAR• If chiller is in a N2 flushed enclosure how does it expel the heat generated?

• Options– Specify a bigger chiller to stretch flow/return pipework to safe(er) area

• How big a chiller, long are the pipe runs, cost?• Improves access to the controller• Minimises future risks

– Replace chiller PID controller with a connector/cable & re-locate PID controller to safe(er) area• Probably needs discussion with manufacturer, will result in ‘non-standard’ unit, cost?• Improves access to the PID controller

– Select a chiller with a readily available PID controller & replace it periodically• What’s the interval ?15/03/2011

Cooling Update 10

Eg. Chiller with a standard PID

15/03/2011

• Grant RC350G– Nearly meets 0.25C inlet

to outlet temperature rise spec.

• Controller– Eurotherm 2132– RS • Stock number 208-2739• £161 + VAT

Cooling Update 11

Eg – Remote Chiller• Assume flow = return = 50m• Extra Power

– Assume 25mm insulation (k=0.04) and a T = 40C• Power ~ 130W• Recall that conservative estimate for internal power is 107W (FE + ambient) – so need 250W

• Pressure Drop– Internal 1.71bar for 6mm bore– External pressure drop vs bore

– Need large bore for low dP but is transit time an issue for control?15/03/2011

Bore (mm) dP (bar) Velocity (m/s)

Transit Time (s)

6 28.5 3.6 148 6.76 2 25

10 2.22 1.3 3812 0.89 0.91 55

Cooling Update 12

Eg. Large(r) Remote Chiller• Huber UC012

– -10 to 40C– 25lpm (0 head)– 2.5bar (max pressure)– 1.2kW @ 15C– 3870 Euro– Popular at CERN

• Nearly OK – would need to reduce

flow/return tubing length– Increase internal tubing to 8mm– Allow larger dT

15/03/2011

Cooling Update 13

Thermo-Neslab ThermaFlex 900/P2

• 750W @ 20C• 10lpm @ 6bar• £3,200

15/03/2011

Cooling Update 14

Summary• Investigate if remote chiller is possible– Location– Pipe-work lengths / routing– Update flow parameters– Investigate chillers

• Back-up– Not sure there is one!• How does an air-cooled chiller dissipate heat if it’s in an

‘sealed’ enclosure for H2/explosion proofing?

15/03/2011