2 Work Done Rotary compressor – Its working and calculations Small Experiment LineBypass Heater CalibrationHeat Balance ReportAccumulator Dry-Out testingAccumulator Cooling Power measurementsCMS Pixel UpgradeUser’s Manual for Building 158
3 Rotary Compressor Sanyo Compressor Model no.: C-C140L5 Dedicated for CO2Two-Stage compressionPressure rating of 90 bar (outlet, 2nd stage)
5 Small Experiment Line 250W Cartridge Heater Swagelok Fittings Concentric Heat Exchanger after Mass Flow MeterActuators for Metering Valves
6 Heater Selection 250 W heater required Cartridge, insertion heater for direct heatingInlet to heater perpendicular to its lengthFlow development analysed for selectionHydrodynamic and Thermodynamic flow developmentLow watt density required
8 Heater Selection Specifications: Watlow Firerod Cartridge Heater Ф -3/8”, Length – 7”Power WWatt Density – 5 W/cm24” No-heat zoneEpoxy Seals to protect from moisture
9 Swagelok Fittings Heater mounted on reducer union Inlet through Welding Tee fittingTube inner dia = 1/2”, heater dia = 3/8”Line between mass flow meter and metering valve in a concentric internal heat exchanger.Whole Assembly Welded Together
12 Actuator Electrical Actuator for Swagelok metering valves Two companies discovered:Hanbay inc. (Canada)Grotec (Germany)Actuator ordered from Hanbay (cost ~ $1500)
13 Bypass Heater Calibration Bypass Heater (2 kW) performance not satisfactoryVirtually no heating at low powers, then sudden overheating at medium-high powersOutput power not equal to power requested through PVSSHeater controlled through phase angle controller (inexpensive way of controlling heater)“Span” setting of heater too narrow. Corrected.
14 Bypass Heater Calibration Tests performed to measure heater power and compare it against input power (through PVSS)System run in single phase to measure enthalpy using Pressure and Temperature.Power o/p = Enthalpy Change x Massflow RatePressure, temperature measured across internal heat exchanger.Output power found to be not equal to input power
16 Bypass Heater Calibration Phase Angle Controller chops up the sine-wave signal (4-20 mA) linear with time, instead of linear with output powerMustapha prepared MATLAB and PVSS programs to correctly calculate output power to match input power.New logic incorporated into PVSS by Lukasz. Works perfectly, and has been tested.
17 Heat Balance Parameters measured Preq Qpump Qheater Qin Qcond Qcomp Heater Calibration tests expanded to give overview of heat balance for entire system.Heat addition/extraction measured to get an idea of system performanceCompressor data also includedParameters measuredPreqQpumpQheaterQinQcondQcomp
20 Heat Balance Conclusions drawn: Up until 1100W, the readings are reliable.Readings above 1100W are unreliable due to premature boiling of CO2 inside the tubes.Offset between requested power and power measured is due to heat added by the pump and surroundings.Compressor cooling capacity is lower than expected (this data is already 2 months old)
21 Accumulator Dry-Out Testing Accumulator heater in thermo-syphon configurationDuring start-up, accumulator heated for long timeAt higher vapor pressure, higher vapor density.At higher density, lower convective currentsRisk of dry-out, heater melting.
22 Accumulator Dry-Out Testing A parameter called Thermal Resistance used to calculate dry-out thresholds𝑅 𝑡ℎ = 𝑇 ℎ𝑒𝑎𝑡𝑒𝑟 − 𝑇 𝑠𝑎𝑡_𝑎𝑐𝑐𝑢 𝐻𝑒𝑎𝑡𝑒𝑟 𝑃𝑜𝑤𝑒𝑟Accumulator heated for long periods with 250, 500, 750, 900 and 1000W powerRth calculated for all data points, and plotted against accumulator saturation temperature.Combined graph for all readings plotted
24 Accumulator Dry-Out Testing Conclusions drawn:At 250W Heater Power, dry- out is not witnessed.Higher the heater power, lower the saturation temperature at which dry-out occurs.Some unexplained bumps are observed at higher powers, through sudden, steep rises and falls in the values of Thermal ResistanceS. No.Heater PowerDry-Out Saturation Temperature (°C)1250N/A2500273750224900195100017
25 Accumulator Cooling Power Tests done to measure cooling power in accumulatorIt was expected that cooling at 100% valve opening should match heating at 100% heater power (1 kW)This was not the caseSome cooling power lost because cooling spiral passes through liquid CO2.
26 Accumulator Cooling Power Accumulator cooled and then heated at specific rates. For example, 50% CV1105 valve opening corresponds to 50% heater power, 500WSlopes of cooling and heating measured.Cooling slope observed to be less than heating slope.Since slope unequal, this method not enough to determine cooling power
28 Accumulator Cooling Power Rough estimate obtained by plotting Heater’s power versus the value ‘dp/dt’ (change in pressure per unit time)dp/dt values of cooling spiral superimposed on heating graph.This gives rough but useful estimate of cooling capacity.
31 Accumulator Cooling Power Cooling Power Measured:Valve OpeningCooling Power25%6050%22575%575100%740
32 Accumulator Cooling Power Conclusions:Cooling power does not correspond to its respective heating power.The maximum cooling power available is only 740W.The cooling power at 25% valve opening is not a quarter of the full cooling power. This is due to the inertia of the fluid.Cooling Power is not completely linear over the entire range.
33 CMS Pixel UpgradeCMS Pixel layout being discussed with various iterations proposed.Latest proposal (at that time) was simulated to measure the fluid temperature and pressure drop. Results were compared with Bart’s results (with his global calculator)Joao’s calculator was used in Matlab, and simulations with Friedel and Chisholm correlations.The simulation results were similar to, but not exactly the same as Bart’s own simulations.
36 User’s ManualThe eventual aim of project was to prepare User Manual to allow external researchers (Belle, SLAC, IBL) to use the system without distracting Bart, Lukasz or Joao!The manual is about 60 pages long and will hopefully be used by someone in the future.