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UCSB 4-Hybrid Thermal Test System Status

UCSB 4-Hybrid Thermal Test System Status. Peltier T/E Element Degradation 28 February 2005. Peltier Failures. Five peltier thermoelectric units have degraded over the past year. February 2004 UCSB (overheated) August 2004 UCSB (overheated) February 2005 UCSB (unknown cause)

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UCSB 4-Hybrid Thermal Test System Status

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  1. UCSB 4-Hybrid Thermal Test System Status Peltier T/E Element Degradation 28 February 2005 CMS 4-Hybrid Test System Sam Burke EE

  2. Peltier Failures • Five peltier thermoelectric units have degraded over the past year. • February 2004 UCSB (overheated) • August 2004 UCSB (overheated) • February 2005 UCSB (unknown cause) FermiLab (unknown cause) CERN (gradual degradation) • Units exhibited reduced thermal efficiency resulting in longer hybrid test cycle times • 65 min vs 40 min • Replacing with new units restores short thermal cycle time. CMS 4-Hybrid Test System Sam Burke EE

  3. Peltier Resistance Changes • Degraded Peltier Units exhibit increased electrical resistance (4-12 amp range) • New Unit: 2.02 ohms • Old Unit (ser No 12): 3.00 ohms • Old FermiLab Unit: 5.0 ohms CMS 4-Hybrid Test System Sam Burke EE

  4. Volt-Ampere Data CMS 4-Hybrid Test System Sam Burke EE

  5. CMS 4-Hybrid Test System Sam Burke EE

  6. Heat Exchange • Cooling Water Flow Rates • 4 L/m suggested by Supercool • 1.3 L/m current use • Measured cooling water exchange rate • 6 deg C at 1.3 L/m at full power CMS 4-Hybrid Test System Sam Burke EE

  7. Temp Rise Calculation • Hybrid Test Chamber Heat Transfer Calculation • Q=mcΔT • Q= heat = P*t=400 watts*Time = 400 J/s*1 s • m=mass of water = 1.0 L/min*σ /60 s/min • = 1/60£*1000cc/£*1g/cc=16 g • c=Specific Heat of water = 4190 J/kgK • ΔT=[Tout-Tin] deg C • ΔT=Q/mc=400J/(4190J/kgK*.016kg)=5.9 deg C rise CMS 4-Hybrid Test System Sam Burke EE

  8. Peltier Failure Mode • Degradation of thermoelectric element due to overheating • Nominal Input Power = (24v*12A)=290 watts • Current Usage = (24v*14a)= 336 watts (+16%) • Future Usage = (20v*10a)= 200 watts (-40%) • It is now not possible to power up Peltier element without cooling water flow, even with a PC failure. CMS 4-Hybrid Test System Sam Burke EE

  9. Current Interlocks • Current Peltier Interlocks • 80 deg C thermal switch on unit • Software has peltier current locked to water flow • Hardware flow interlock (recently installed) CMS 4-Hybrid Test System Sam Burke EE

  10. New Sensor Interconnect with Peltier Hardware Interlock CMS 4-Hybrid Test System Sam Burke EE

  11. Plans • Have degraded units refurbished rather than scrapped. • New unit $400 ea • Refurbished unit $120 parts and $40 labor • Limit Maximum Power Levels • Voltage limit of 24 vdc • Current limit from 14 to 10 adc (17% reduction) • CERN has been using 10amp limit for last year • FERMILAB has agreed to 10 amp limit • UCSB should use this limit, Time=+1min on cycle CMS 4-Hybrid Test System Sam Burke EE

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