1. Final Report
Viren Bhanot

2. Work Done Rotary compressor – Its working and calculations
Small Experiment Line
Bypass Heater Calibration
Heat Balance Report
Accumulator Dry-Out testing
Accumulator Cooling Power measurements
CMS Pixel Upgrade
User’s Manual for Building 158

3. Rotary Compressor Sanyo Compressor Model no.: C-C140L5
Dedicated for CO2
Two-Stage compression
Pressure rating of 90 bar (outlet, 2nd stage)

4. Matlab Compressor Calculations

5. Small Experiment Line 250W Cartridge Heater Swagelok Fittings
Concentric Heat Exchanger after Mass Flow Meter
Actuators for Metering Valves

6. Heater Selection 250 W heater required
Cartridge, insertion heater for direct heating
Inlet to heater perpendicular to its length
Flow development analysed for selection
Hydrodynamic and Thermodynamic flow development
Low watt density required

7. Heater Selection Correlations Used: Hausen Stephan Shah/London
Flow Development
Fully Developed
Thermodynamically developing, Hydrodynamically developed
Simultaneously developing

8. Heater Selection Specifications: Watlow Firerod Cartridge Heater
Ф -3/8”, Length – 7”
Power W
Watt Density – 5 W/cm2
4” No-heat zone
Epoxy Seals to protect from moisture

9. Swagelok Fittings Heater mounted on reducer union
Inlet through Welding Tee fitting
Tube 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

10. CAD Model

11. Heater Assembly

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 satisfactory
Virtually no heating at low powers, then sudden overheating at medium-high powers
Output power not equal to power requested through PVSS
Heater 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 Rate
Pressure, temperature measured across internal heat exchanger.
Output power found to be not equal to input power

15. Bypass Heater Calibration

16. Bypass Heater Calibration
Phase Angle Controller chops up the sine-wave signal (4-20 mA) linear with time, instead of linear with output power
Mustapha 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 performance
Compressor data also included
Parameters measured
Preq
Qpump
Qheater
Qin
Qcond
Qcomp

18. Heat Balance

19. Heat Balance

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 configuration
During start-up, accumulator heated for long time
At higher vapor pressure, higher vapor density.
At higher density, lower convective currents
Risk of dry-out, heater melting.

22. Accumulator Dry-Out Testing
A parameter called Thermal Resistance used to calculate dry-out thresholds
𝑅 𝑡ℎ = 𝑇 ℎ𝑒𝑎𝑡𝑒𝑟 − 𝑇 𝑠𝑎𝑡_𝑎𝑐𝑐𝑢 𝐻𝑒𝑎𝑡𝑒𝑟 𝑃𝑜𝑤𝑒𝑟
Accumulator heated for long periods with 250, 500, 750, 900 and 1000W power
Rth calculated for all data points, and plotted against accumulator saturation temperature.
Combined graph for all readings plotted

23. Accumulator Dry-Out Testing

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 Resistance
S. No.
Heater Power
Dry-Out Saturation Temperature (°C) 1
250
N/A 2
500 27 3
750 22 4
900 19 5
1000 17

25. Accumulator Cooling Power
Tests done to measure cooling power in accumulator
It was expected that cooling at 100% valve opening should match heating at 100% heater power (1 kW)
This was not the case
Some 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, 500W
Slopes 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

27. Accumulator 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 Opening
Cooling Power
25% 60
50%
225
75%
575
100%
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 Upgrade
CMS 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.

34. CMS Pixel Upgrade

35. CMS Pixel Upgrade

36. User’s Manual
The 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.

37. Thank You