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)
UCSB 4-Hybrid Thermal Test System Status
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UCSB 4-Hybrid Thermal Test System Status Peltier T/E Element Degradation 28 February 2005 CMS 4-Hybrid Test System Sam Burke EE
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
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
Volt-Ampere Data CMS 4-Hybrid Test System Sam Burke EE
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
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
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
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
New Sensor Interconnect with Peltier Hardware Interlock CMS 4-Hybrid Test System Sam Burke EE
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
