Final ReportViren Bhanot

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

Rotary Compressor

Sanyo Compressor

•Model no.: C-C140L5

•Dedicated for CO2 •Two-Stage

compression•Pressure rating of

90 bar (outlet, 2nd stage)

Matlab Compressor Calculations

Small Experiment Line

•250W Cartridge Heater•Swagelok Fittings•Concentric Heat Exchanger after Mass

Flow Meter•Actuators for Metering Valves

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

Heater Selection

Correlations Used:•Hausen•Stephan•Shah/London

•Flow Development•Fully Developed•Thermodynamicall

y developing, Hydrodynamically developed

•Simultaneously developing

Heater Selection

Specifications:•Watlow Firerod Cartridge Heater•Ф -3/8”, Length – 7”•Power - 250 W•Watt Density – 5 W/cm2

•4” No-heat zone•Epoxy Seals to protect from moisture

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

CAD Model

Heater Assembly

Actuator• Electrical Actuator for

Swagelok metering valves

Two companies discovered:• Hanbay inc. (Canada)• Grotec (Germany)

• Actuator ordered from Hanbay (cost ~ $1500)

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.

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

Bypass Heater Calibration

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.

Heat Balance• 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

Heat Balance

Heat Balance

Heat BalanceConclusions 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)

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.

Accumulator Dry-Out Testing

•A parameter called Thermal Resistance used to calculate dry-out thresholds

•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

Accumulator Dry-Out Testing

Accumulator Dry-Out Testing

 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

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

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.

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

Accumulator Cooling Power

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.

Accumulator Cooling Power

Cooling Power Measured:

 Valve Opening

 

 Cooling Power

25% 60

50% 225

75% 575

100% 740

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.

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.

CMS Pixel Upgrade

CMS Pixel Upgrade

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.

Thank You