Petra Janickova

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Investigation on Pressure Drop Phenomena of CO 2 in Two Phase Flow for Detector Cooling. Advantages of CO 2 The test facilities Pressure drop measurements Comparison to the model Conclusion. Petra Janickova. 21. February 2011. 1. Advantages of CO 2. - PowerPoint PPT Presentation

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Petra Janickova 21. February 2011

Investigation on Pressure Drop Phenomena of CO2 in Two Phase Flow for Detector CoolingAdvantages of CO2 The test facilitiesPressure drop measurementsComparison to the model Conclusion

1Petra Janickova 21. February 2011

higher latent heat, 2 times more then C6F14 higher operation pressure then C3F8 (at -20C it has 2 bar) smaller gas bubbles in two phase flowlower probability of plugging in mini channels lower Global Warming Potential CO2 = 1 ; C6F14 = 7400 resistant to radiation high heat transfer coefficient especially in two phase flow

1. Advantages of CO2

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Petra Janickova 21. February 2011

2. The different supply systemsSMALL SCALE SYSTEM: Compressing CondensingLARGE SCALE SYSTEM: Liquefying Pumping

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The portable test section

Expansion Heating Measurement Heating

wall temperaturefluid temperature4Petra Janickova 21. February 2011

3. Experimental results

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3. Experimental results

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3. Possible reasons for the deviationblocked capillaries

wrong measurement of the mass flow

different kind of pumpMeasurement of the pressure drop by means of the temperature sensors

Calibration of the mass flow meter in single phase

Measurement of eventual pressure oscillations in the system

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3. Reasons for the deviationMeasurement of the pressure drop by means of the temperature sensors

The deviation of calculated and measured mass flow is identical at both systems

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3. Reasons for the deviationCalibration of the mass flow meter in single phase The coriolis mass flow meter is measuring by means of the coriolis effect Thus able to measure in liquid and gas phase

A lower accuracy of the mass flux meter at low mass flux < 500 kg/m2s Additional vibrations in the system can effect the measurement

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3. Reasons for the deviationCalibration of the mass flow meter in single phase The deviation in mass flow is not effecting the pressure drop significantly

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Measurement of eventual pressure oscillations in the system

According to the datasheet: f = 2.33 Hz 3. Reasons for the deviation

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Measurement of eventual pressure oscillations in the system

Measurement in the test sectionA = 25 mbar 3. Reasons for the deviation

More measurements has to be done to prove the influence of the oscillations12Petra Janickova 21. February 2011

4. Proof of the model

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4. Proof of the model The deviation is growing bigger with higher mass flux and is negative at low mass flux

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4. Proof of the model

The friction factor is more depending on the mass flux: Introduction of a new friction factor with a mass flux ratio

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4. Proof of the model The model is not including the roughness Introduction of an additional part concerning the roughness

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5. Conclusion The pressure oscillations caused by a pump can cause a problem during the operation of the cooling plant for CMS. A solution could be: A good damping system A not fluctuating pump (gear pump) The coriolis mass flow meter should be calibrated before use The latest released model has to be improved and therefore more measurements has to be done at high mass flow the dryout inception the pressure drop Never trust the pressure restriction of the valves while doing a pressure test!

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Thank you for your attention!

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