CEDAR Cooling(CEDAR Meeting 23rd May 2011)

Tim Jones

Cooling Update 2

Overview• Review of Past Cooling System Specification– 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

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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

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Cooling Update 4

Pipe-work Geometry• External Interconnect– Fundamental assumption was that cooling plant

could be situated within beam-line area• Flow and return lines 7m long with a bore of 12mm

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

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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

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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

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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 Location• 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 Is this OK - ATEX Zone?

– If chiller is in a N2 flushed enclosure (ATEX) how does it expel the heat generated?

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

• Improves access to the controller• Minimises future risks• How big a chiller, long are the pipe runs, cost?• Is it OK to run activated fluid outside the zone ?

– 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 ?

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Cooling Update 10

Eg. Chiller with a standard PID

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• 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

Large(r) Remote Chillers• Huber UC012

– 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

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• Thermo-Neslab Thermaflex 900/P2– 750W @ 20C– 10lpm @ 6bar– £3,200

Cooling Update 13

Summary• Investigate if remote chiller location is possible– For 50m flow/return pipe-work need > 15mm bore to avoid

narrowing range of chillers– Looks OK

• Need to understand if there are any other issues before taking final decision

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Chiller Option Issues

Local (<7m)

Radiation controlled area limits access for (manual) adjustmentRadiation damage may limit sophistication of system controller / communications interfacesWhat is the ATEX classification of the beam line area near the wall?

Remote (~50m)

Is it OK to have contaminated fluid circulating outside zone?Do chillers need to be mounted in a bund to contain a potential leak?

Cooling Update 14

Points Raised• Radiation

– Dose is not an issue (few Gray / year)– Concern is that SEU might cause the PID controller to malfunction - may need to devise a technique to

check and provide a system reset– There would not be a radiation issue for the fluid if the chiller were to be located remotely

• Access– Access to the CEDAR area will be rapid and on a similar time-scale to that to anywhere else in the

experimental hall. • There’s no disadvantage in locating the chiller 7m from CEDAR

– The only location offering better access for the chiller is ~ 100m away from the CEDAR (not 50)

• ATEX– The ATEX classification of the space near the zone wall (7m from CEDAR) is expected to be confirmed

as ‘none’ in June

• Slow Control– Temperatures and flows, etc.. Will be monitored in the DCS system via ELMBs. The level of integration

between the monitoring and the control of the chiller set-point is not well understood. (eg. RS232 control is difficult to implement).• The working assumption is that the DCS system will issue a warning if a problem with the cooling is detected and

an ‘expert’ will then have to be called to investigate

• Power Loads & faults– Query concerning effects of varying power loads on temperature distribution within enclosure.

• Need to understand FE/PMT power in fault situations and evaluate how temperatures will change.15/03/2011

Cooling Update 15

Decisions• Cooling system based on ‘Option 1’

– Minimum complexity

• Chiller located on wall near CEDAR (<7m)– ATEX OK– Access no worse than anywhere else– Better control

• Consider options for remote PID controller / DCS interface– Minimise concerns for SEU

• DCS will not ‘automatically’ define the temperature set-point

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