Status of co2 cooling
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Status of CO2 cooling. CMS Upgrade Workshop FNAL. Participating places (1). RWTH Aachen – Lutz Feld, Michael Wlochal, Jennifer Merz IPN Lyon – Nick Lumb, Didier Contardo University Karlsruhe – Wim de Boer et al. Fermilab – Simon Kwan, Richard Schmitt, Terry Tope, Kirk Arndt.

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Status of CO2 cooling

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Status of co2 cooling

Status of CO2 cooling

CMS Upgrade Workshop


Hans Postema - CERN

Participating places 1

Participating places (1)

  • RWTH Aachen – Lutz Feld, Michael Wlochal, Jennifer Merz

  • IPN Lyon – Nick Lumb, Didier Contardo

  • University Karlsruhe – Wim de Boer et al.

  • Fermilab – Simon Kwan, Richard Schmitt, Terry Tope, Kirk Arndt

Hans Postema - CERN

Participating places 2

Participating places (2)

  • PSI – Roland Horisberger

  • CERN Cryolab – Friedrich Haug, Jihao Wu, Torsten Koettig, Christopher Franke

  • University Esslingen – Walter Czarnetzki, Stefan Roesler

  • CERN DT group – Joao Noite, Antti Onnela, Paolo Petagna, Paola Tropea,

Hans Postema - CERN

Participating places 3

Participating places (3)

  • NIKHEF Atlas – Bart Verlaat, Auke-Pieter Colijn

  • SLAC Atlas – Marco Oriunno

  • CERN Atlas – Danilo Giugni, Jan Godlewski, Jose Direita

  • EPFL Lausanne – John Thome et al.

  • CERN CMS – Duccio Abbaneo, Hans Postema

Hans Postema - CERN

Co2 full scale setup

CO2 Full scale setup

  • Following the example of the LHCb cooling plant, we will build a full scale setup for testing purposes

  • Setup based upon CMS-TEC cooling plant provided by Karlsruhe

  • R404 chiller has cooling power of 4 kW at

    -35 C

  • System uses Lewa pump and SWEP heat exchanger also provided by Karlsruhe

Hans Postema - CERN

Lhcb schematic

LHCb schematic

Hans Postema - CERN



  • Collaboration, involving people from NIKHEF, CERN-Atlas, CERN-DT, CERN-Cryolab, CERN-CMS

  • Schematic created in August, finalized and approved in September.

  • Parts list created in August, approved, except for a few components.

  • Budgets identified, ordering has started.

Hans Postema - CERN



Hans Postema - CERN

Cms tec cooling plant

CMS-TEC cooling plant

Hans Postema - CERN

Lewa pump

LEWA pump

Hans Postema - CERN

Swep heat exchanger

SWEP heat exchanger

Hans Postema - CERN



  • Full agreement on schematic (P&I)

  • Detail design is advancing

  • Budgets agreed and available

  • Ordering has started

  • Contact with CERN safety established

    • In principle no serious obstacles

    • Will work together to obtain certification

  • Project is advancing at full speed

Hans Postema - CERN

Cern cryolab


CERN Cryolab

  • CO2 cooling for pixel detectors

  • Investigation of heat transfer

Christopher Franke, Torsten Köttig, Jihao Wu, Friedrich Haug



  • Objectives of the study

  • Test setup

  • Measurement conditions

  • Investigation tube diameter

  • Summary

Status of co2 cooling

Objectives of the study

Experimental verification of 2-phase CO2 flow regimes and stability criteria of CO2 flow in minichannels suitable for cooling of the upgraded pixel detector of CMS.

Establish a rather comprehensive experimental database in the range of relevant mass flux and heat flux α = f(x,q,G,Tsat).

Validation of existing correlations for heat transfer coefficient and pressure drop.

If necessary, adapt existing correlations to the database at the range of interest.

Test setup

Test setup

Cooling cycle schematic and log(p)-h diagram


Test setup1

Test setup

Piping and Instrumentation Diagram

Status of co2 cooling

Test setup

  • Operating temperatures -40°C to -5°C

  • Mass flow up to 1.5 g/s

  • Heat flux at test section up to 30 kW/m²

  • Tube diameter (test section) up to 2.0 mm

  • Design pressure of the setup 100 bar

  • Cooling power Pulse Tube Cryocooler 150W@225K

  • Insulation vacuum 5⋅10-5 mbar

Test setup2

flow direction

Test setup

  • Stainless steel

  • Length of the actual test section (heated part)

  • l = 0.15 m

  • Inner diameter di = 1.4 mm

  • Wall thickness s = 120 μm

  • Max. heat flow QTS = 30 W

Test setup3

Test setup

Test setup4

Test setup

Measurement conditions

Measurement conditions

1. Saturation Temperatures:

Change in saturation temperature causes a change of the fluid properties which on the other hand influence the flow pattern and heat transfer coefficient respectively!

  • Following fluid properties are used for calculation:

  • Density ρ (liquid and gas phase)

  • Dynamic viscosity η (liquid and gas phase)

  • Surface tension σ (liquid phase)

  • Latent heat of vapourization hLV

Proposed temperature levels for measurement:

Measurement conditions1

Measurement conditions

1. Saturation Temperature:

ΔT = 25 K

Δσ = 5,4E-3 N/m

surface tension in N/m

temperature in °C

Measurement conditions2

Measurement conditions

2. Mass flow (density):

Change in mass flow m and mass flow density G respectively influences the flow pattern which on the other hand determine the heat transfer coefficient!

Proposed mass flow (density) steps for measurement:

Measurement conditions3

Measurement conditions

2. Mass flow (density):

Measurement conditions4

Measurement conditions

3. Heat flux test section:

Change in heat flux and influences the quality factor where dryout occure.

  • There are 2 theoretical heat flux thresholds:

  • Onset of nucleate boiling qONB = 1 kW/m² (VDI Wärmeatlas)

  • Critical heat flux qcrit = 794 kW/m² (S.S. Kutateladze)

Proposed heat flux levels for measurement:

Measurement conditions5

Measurement conditions

3. Heat flux test section:

Measurement conditions6

0,05 ≤ x ≤ 1

Δx ≈ 0,025











Measurement conditions

Due to CMS requirements of 150W@5.5m (4.1W@0.15m) at -12°C, tube diameter 1.4 mm the following measuring plan is proposed.

Investigation tube diameter

Investigation tube diameter

Investigation tube diameter1

Investigation tube diameter

Investigation tube diameter2

Investigation tube diameter

Inner diameter

Wall thickness



  • Test session for 1.4 mm inner diameter tube in horizontal

  • orientation (according to CMS requirements)

  • This results an outcome of 252 (441) cases α = f(x)

  • Good database for comparison with existing flow maps

  • Good database for comparison with existing calculation models

  • for heat transfer coefficient

  • Extensive commissioning and validation of the setup

Pixel co 2 cooling test status

Physics Department

Detector Technology Group

Pixel CO2 Cooling Test Status

João Noite PH-DT

Co 2 cooling test status

CO2 Cooling Test Status

  • 1.4mm ID, 5.5m length cooling pipe tested in different heat loads and flow conditions.

  • Available empirical models for two phase pressure drop prediction were used and compared with experimental data.

  • Upgrades on the test setup are being made in order to improve the measurements.

  • Pixel cooling pipe mockup provided by PSI will be tested during the following weeks.

João Noite PH-DT

Co 2 cooling test setup











CO2 Cooling Test Setup

João Noite PH-DT

P h diagram

p-h Diagram


Pressure [Bar]



Water Bath Heater

Enthalpy [KJ/Kg]

João Noite PH-DT

Latest results

Latest Results

João Noite PH-DT

Latest results1

Latest Results

João Noite PH-DT

Latest results2

Latest Results

João Noite PH-DT

Test stability

Test Stability

Stable Readings

Unstable Readings

João Noite PH-DT

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