co 2 as a potential cooling medium for detector cooling at cern

CO2 as a potential cooling medium

for detector cooling at CERN

16.01.2009Project Tutor: Prof. Dr.-Ing. W. Czarnetzki M. Renner, S. Erhardt, S. Feghelm, J. Bürkle

2

• Project conception

• CO2 overview

• Reverse Rankine Cycle

• Components

• Calculations /dimensioning

• Heat transmission

• Perspective

CO2 as a potential cooling medium for detector cooling at CERN

Abstract:

Project conception

CO2 overview

Reverse Rankine Cycle

Components

Calculations / dimensioning

Heat transmission

Perspective


3


• CO2 overview


• Components



• Perspective


Project definition

Today’s state of the art

Existing applications and look for trends

CO2 as cooling medium

Laboratory and test facility design

Correlations for CERN

Project conception


4


• CO2 overview


• Components



• Perspective


Project structureProject conception


5


• CO2 overview


• Components



• Perspective


TimetableProject conception


6


• CO2 overview


• Components



• Perspective


CO2 overview

CO2 sublimates under ambient pressure direct from solid to steam

and reaches a temperature of -78,5°C.

CO2 is color- and odorless, good soluble in water and not soluble

with mineral oil.

CO2 has a critical point at 31,06°C and 73,83 bar.

CO2 is non flammable, non explosive, non corrosive and does not

corrode sealant and lubricant.

30vol.% (300'000 ppm) of CO2 in the air are lethal.

CO2 overview


7


• CO2 overview


• Components



• Perspective





8


• CO2 overview


• Components



• Perspective


Components of the laboratory CO2 cycle

Compressor (Bock)

Expansion valve

Condenser Evaporator

Components


9


• CO2 overview


• Components



• Perspective


CO2 compressor

Technical data: 2-cylinder, semi-hermetic compressor

Limitation of use:

Operation point: Condensing temperature: 0°C

Evaporation temperature: -40°C

Cooling capacity at operation point: 6058 W

Attachment: continuous speed control

Components

HGX12P/60-4 CO2


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• CO2 overview


• Components



• Perspective


Components

Condenser

Evaporator

Throttle valve

Reservoir

All elements will be appointed over one company.

Components


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• CO2 overview


• Components



• Perspective


CO2 Reverse Rankine Cycle in the T,s-diagram

Calculation / dimensioning

1-2: Isentropic compaction

2-3: Isobar condensation

3-4: Isenthalpe choke

4-1: Isobar evaporation


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• CO2 overview


• Components



• Perspective


Calculation result

Input based on operation point:

Cooling capacity 6058 W

Isentrope efficiency 49%

Evaporation temperature -40°C

Condensing temperature 0°CCalculation / dimensioning

CO2 Reverse Rankine Cycle 1 – 2 – 3 – 4 1 – 2‘ – 3 – 4 1 – 2“ – 3 – 4

Mass flow 25,78 g/sec 25,74 g/sec 25,74 g/sec

Rejected heat flow -7476 W -8226 W -8952 W

Compressor power consumption

1418 W 2890 W 2890 W

Coefficient of performance 4,272 2,1 2,1

It is a obvious difference to the ideal process expected.

The compressor don’t work isentropic.

The condenser has to provide a minimum heat flow of 9 kW.

The evaporator has to provide a minimum heat flow of 6,5 kW.


13


• CO2 overview


• Components



• Perspective


Detector cooling with CO2 cycle

Pilot study

Test state

• Liquid CO2 through thin and heated capillary tubes

• Measuring of heat transmission characteristics

Identify the formula coherences

Correlate formula with the measured data

Heat transmission


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• CO2 overview


• Components



• Perspective


Flow Boiling

Heat transmission


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• CO2 overview


• Components



• Perspective


Correlations

Heat transmission separated into two independent rates:

Convective Heat transmission heat transmission in nucleate boiling

Heat transmission(z)αk (z)αB

α(z)


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• CO2 overview


• Components



• Perspective


Yoon

Horizontal microtubes Critical quality

Constant heat flux

below xcr above xcr

4,71,642,12Lcr,t BdBo)(1000Re38,27x

2B

2K )α(S)α(Eα

π

π

2

α)θ(2αθα wetdryGdry


17


• CO2 overview


• Components



• Perspective


Steiner - Horizontal

Horizontal thick-walled tubes

Constant heat flux

Start of nucleate boiling:

3 3B

3K α(z)α(z)α(z)

vGk

L0Sonb

Δhρr

ασT2q

onbqq onbqq

Kαα(z)


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• CO2 overview


• Components



• Perspective


Steiner - Horizontal

Convective

Nucleate boiling

Heat transmission


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• CO2 overview


• Components



• Perspective


Steiner - Vertical

Heat transmission

Convective

Nucleate boiling

no mass flux

no quality


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• CO2 overview


• Components



• Perspective


Steffen Grohmann – Horizontal microtubes

Working fluid: Argon

No mass flux and quality dependence in microtubes

Strong influence of surface tension in microtubes

Phase seperation occures less likely

αB based on VDI-Wärmeatlas correlations for vertical tubes


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• CO2 overview


• Components



• Perspective


Options for future work

Perspective

Ordering the components (condenser, evaporator).

Setup and launch of the cooling machine in the laboratory.

Tests regarding the heat transmission and conventional

cycle.

Calculation of the cycle based on the measured data.

Optimization of the cooling machine.


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• CO2 overview


• Components



• Perspective


Future collaboration with CERN

Experiments on heat transmission:

with several tubes types

in a evaporation temperature range from -25°C to -50°C

in a pressure range from 7bar to 40bar

Correlation of the measurements Perspective

co 2 as a potential cooling medium for detector cooling at cern

Documents

cooling medium laboratory

trends co2

ppm of co2

cern timetableproject

cern components

cernproject tutor

cern abstract

overviewproject tutor