TCS Chiller Performance Review - PowerPoint PPT Presentation

About This Presentation

TCS Chiller Performance Review


Site chilled water and TCS table water pipes interlaid and touching ... After noise test, chiller was switched on ... Much damage and corrosion to the chiller ... – PowerPoint PPT presentation

Number of Views:308
Avg rating:3.0/5.0
Slides: 13
Provided by: sand56


Transcript and Presenter's Notes

Title: TCS Chiller Performance Review

TCS Chiller Performance Review
  • Phil Willems
  • Nov. 17, 2004

Design Requirements
  1. Laser temperature around room temperature, .5K
  2. Flow rates

Device Max power dissipated Flow requirement Source of requirement
Carbon dioxide laser 80W ½ gpm Access Laser Co.
Laser power supply 40W cool to the touch Access Laser Co.
AOM 30W 250 ml/min IntraAction, Inc.
AOM driver TBD TBD IntraAction, Inc.
  1. Noise acoustic and EMI must be under ambient at
    nearest sensitive device (optical lever system)
  2. Monitoring and control from control room using
  3. Leak tight and robust

Commissioning Timeline
  • Device was installed on 2K Y arm Oct. 27-29
  • Device was commissioned from Oct. 29 to Nov. 8.
  • Commissioning paused after overheating incident
    Nov. 6-7.
  • Forensics from Nov. 8 to today.

  • Site chilled water delivered to chiller from over
    100 feet away through uninsulated copper pipe
  • This may account for some temperature issues and
    surges during control valve operation
  • Site chilled water and TCS table water pipes
    interlaid and touching
  • Insulation of TCS table supply pipe required for
    temperature stability
  • Prototype control electronics not plug and play
  • Control software implemented but not safety

  • Submerged thermistor failed after 2 days (Nov. 1)
  • Thermistor was fine problem later traced to bad
    solder joint outside chiller
  • Short term solution was to glue another
    thermistor to pipe leaving chiller
  • Laser power stabilized without AOM on (Nov. 3-5)
  • Laser power unstable with AOM on (Nov. 5)
  • Chiller noise performance verified (Nov. 6-7)
  • http//

Overheating Incident
  • After noise test, chiller was switched on to run
  • Apparently, one or both pumps failed to switch on
  • System ran at very high temperature for about 1-2
  • Much damage and corrosion to the chiller
  • Thermistors on TCS table showed no overheating,
    no flow to table- TCS table not affected

Why a Chiller Is Not a Boiler
Overheating Incident Analyzed
  • Without submerged thermistor operating, no way to
    monitor chiller reservoir temperature
  • Without software interlocks programmed, system
    could not power down safely had the submerged
    thermistor worked
  • Had system been fully operational before running
    unattended chiller would have safely shut itself
  • Why did pump fail to start?
  • LHO reports that all Rio pumps studied failed to
    start 100 of the time

  • Chiller disassembled, analyzed, and rebuilt
  • Now it runs well even with the AOM on (for 30
    minutes at least)
  • Rio 1100 pumps tested for reliability
  • One pump tested by hand- 200 starts without
  • One pump tested by robot- robot itself not 100
    reliable, but pump starts 15,000 times without
  • Rio 2100 pump known to fail at LHO now under test
  • Coolant corrosion tests
  • Chloramine T not compatible with chiller
    components under accelerated aging test
  • Propylene glycol and sodium hydroxide are

Chiller Performance After Rebuild
Final Results Compared to Requirements
  • Temperature of chiller and laser held to within
    .5K, as required
  • Flow rate is 1.3GPM, as required
  • Acoustic and electromagnetic noise is below
    ambient, as required
  • Operation fully controlled and monitored from the
    control room, as required
  • System is not yet robust to failure modes
  • Design not fully implemented, software interlocks
    missing when needed
  • New safeties can be added without change to
    conceptual design

Are the Design Requirements Good Enough?
  • The TCS laser stability is unverified even though
    the TCS chiller meets requirements. Laser power
    and coolant temperature fluctuations are
    frequently correlated.
  • Is .5K temperature stability sufficient?
  • Is 1.3GPM flow sufficient?
  • Recommend that no more TCS chillers be installed
    until reconditioned prototype performance is
  • New chiller parts will replace boiled parts
  • Software interlocks will be fully implemented
  • Hardware interlocks under consideration
  • Plan new commissioning effort Nov. 29-Dec. 3.
Write a Comment
User Comments (0)