CEDAR Cooling (CEDAR Meeting 23 rd May 2011) Tim Jones

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 15/03/20112Cooling Update

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 40  C and internal wall is at 20  C – Power = 0.05 x 2.16 x 20 / 0.05 = 47W Total Power – 64 (FE) + 47(env) = 107W 15/03/20113Cooling Update

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 15/03/20114Cooling Update

Draft Chiller Requirements T rise0.5deg C0.25deg C0.10 deg C Bore4mm6mm8mm4mm6mm8mm4mm6mm8mm Flow Pressure Tabulate Flow and pressure for different bores of the internal pipe work and desired temperature rise Chiller Specifications (preliminary web-trawl) ModelPowerFlow 0 bar)Pressure (bar) Fryka DLK  C Grant RC350G 20  C lpm) Neslab Thermoflex 900/P2 40  C 12.5 bar)7 bar Jubalo FC600S 20  C Cole-parmer WU  C Lauda WK 20  C10 15/03/20115Cooling Update

Control Issues – Maintain the PMT arrays at a given temperature – Control the heat transfer between the box and the CEDAR Options 1.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 box 15/03/20116Cooling Update

Option 1 15/03/20117Cooling Update

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 enclosure 15/03/2011Cooling Update8

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 ? 15/03/2011Cooling Update9

Eg. Chiller with a standard PID 15/03/2011Cooling Update10 Grant RC350G – Nearly meets 0.25C inlet to outlet temperature rise spec. Controller – Eurotherm 2132 – RS Stock number £161 + VAT

Eg – Remote Chiller Assume flow = return = 50m Extra Power – Assume 25mm insulation (k=0.04) and a  T = 40  C 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? 15/03/2011Cooling Update11 Bore (mm)dP (bar) Velocity (m/s) Transit Time (s)

Large(r) Remote Chillers Huber UC012 – 25lpm (0 head) – 2.5bar (max pressure) – 15C – 3870 Euro – Popular at CERN – Nearly OK would need to reduce flow/return tubing length Increase internal tubing to 8mm Allow larger dT 15/03/2011Cooling Update12 Thermo-Neslab Thermaflex 900/P2 – 20C – 6bar – £3,200

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 15/03/2011Cooling Update13 Chiller Option Issues Local (<7m) Radiation controlled area limits access for (manual) adjustment Radiation damage may limit sophistication of system controller / communications interfaces What 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?

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. 15/03/2011Cooling Update14

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 15/03/2011Cooling Update15