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He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET Ch. Darve 1 , E. Blanco 2 , Y. Huang 1 , T. Nicol 1 , T. Peterson 1 and Rob van Weelderen 2 1 Fermi National Accelerator Laboratory, Batavia, IL, 60510, USA 2 CERN, European Organization for Particle Physics, Geneva, 1211, CH.

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He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET Ch. Darve1, E. Blanco2, Y. Huang1, T. Nicol1, T. Peterson1 and Rob van Weelderen21 Fermi National Accelerator Laboratory, Batavia, IL, 60510, USA2 CERN, European Organization for Particle Physics, Geneva, 1211, CH

headlines
Headlines
  • Overview on the LHC IR inner triplet
  • IT-HXTU test description and purpose
  • Thermal measurements under investigation
  • Results and discussion
  • Consequences on the inner triplet

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

overview on the lhc ir inner triplet
Overview on the LHC IR inner triplet

Qnom=212.9W

Qult= 472.8W

  • Eight inner triplets located @ the Interaction Regions.
  • C-08C-03 LHC Interaction Region Quadrupole
  • Cryostat Design
  • Concerns:
  • Large dynamic heat loads @ 1.9 K
  • Require a large Heat Exchanger tube

Qnom=61.1W

Qult= 97.5W

Qnom=60.1W

Qult= 95.1W

Qnom=212.9W

Qult= 472.8W

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

from the lhc ir inner triplet to the it hxtu
From the LHC IR inner triplet to the IT-HXTU

Inner triplet

200 W

Heat transfer

1.4 %

IT-HXTU

  • Four similar modules (7 m x ø 0.8 m) to simulate the IT cooling scheme.
    • Magnet simulators (resistive heaters)
    • Full He II capacity (~800 l)

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

view of the it hxtu
View of the IT-HXTU

The feedbox without the thermal shield

and vacuum vessel

support

Side view of one of the four identical modules

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

view of the it hxtu1
View of the IT-HXTU

Heat exchanger tube

Connecting pipes

Pressurized He II circuit

Sat He II supply

Shield cooling pipes

Magnet simulator pipe

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

view of the it hxtu2
View of the IT-HXTU

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

purpose of the it hxtu
Purpose of the IT-HXTU
  • Validation of the the inner triplet cooling scheme by checking

the max. temperature rise in the stagnant and pressurized He II.

  • Validation of theoretical estimation of the heat transfer in Pressurized He II.
  • Measurement of the heat exchanger tube wetted area.
  • Development of the Nonlinear Model-Based Predictive Control.

C-02B-03 Nonlinear Advanced Control of the LHC Inner Triplet Heat Exchanger Test Unit

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

the it heat exchanger tube
The IT Heat Exchanger tube

Stainless steel flange

Corrugated tube

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

process and instrumentation diagram
Process and Instrumentation Diagram
  • The heaters provide the heat load
  • The JT valve controlled the saturated He II flow
  • The thermal equilibrium is dictated by the evolution of the dry-out point and the overflow in the accumulator

Connecting pipes

accumulator

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

instrumentation
Instrumentation

Temperature sensors implemented in the pressurized He II bath

  • Error of +/-5 mK on the temperature measurements.
  • Stainless steel tubes to route the wires.

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

acquisition and control system
Acquisition and Control system
  • Instrumentation (temperature sensor, pressure transducers, mass-flowmeter, controlled valves…)
  • An industrial PLC acquires and controlled the sensors and valves.
  • Profibus fieldbus routes the information to the acquisition system.
  • PCVue32 is the software used for the graphic interface, control and acquisition.
  • Ethernet network permits us to acquire and supervise the equipment

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

heat transfer in superfluid helium
Heat transfer in superfluid helium

Gorter-Mellink equation:

with 1/f(T) = thermal conductivity of He II

If T=1.85 K to 1.95 K @ 1 bar

then 1/f(T) = 1200 W3/cm5K for m=3

Heat flux (W/cm2)

For estimating the temperature difference in regions with distributed heat input, we can use:

Heat flux through the superfluid into the system

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

heat transfer and kapitza effect
Heat transfer and Kapitza Effect

Determination of the Kapitza resistance:

Small scale Heat Exchanger test @ FNAL

Rth=(Tpres-Tsat)/Qelec

Rkapitza

Rth=2.Rkapitza+Rcu=a(1/Tpres3)+b

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

heat transfer and kapitza effect1
Heat transfer and Kapitza Effect

Bronze (95%Cu-5% Sn)

OFHC- @ IT-HXTU

OFHC+ HCl

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

installation commissioning of the it hxtu
Installation & Commissioning of the IT-HXTU

1. Measurement of the heat exchanger tube deflection :< 8 mm

2. Installation on the supports (1.4%)

3. Connecting the 4 modules

4. Pressure test: 2.5 bar abs

5. Leak check: 10-8 mbar l/s (@120 mbar)

6. Mechanical calibration of the controlled valves

  • At cryogenic temperatures
    • Time constants for the thermal equilibrium: 4-6 hours
    • LHe velocity measurements:10 cm/s
    • Controlled valves, JT valve: PID parameters
    • Recalibration of thermometers
    • Calibration of the turbine mass-flow meter
    • Calibration of the JT opening
    • Static heat load measurements

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

determination of the static heat loads
Determination of the static heat loads
  • The static heat load was measured using the enthalpy balance between the JTvalve and the accumulator

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

nominal condition
Nominal condition

Total integrated heat load to Inner Triplet :

Nominal Condition = 211 watt

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

nominal condition1
Nominal condition

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

it hxtu ultimate condition q 315 w
IT-HXTU Ultimate condition Q= 315 W

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

comparison with calculation
Comparison with calculation

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

dt vs heat load t sat 1 90 k 21 mbar
DT vs. heat load - Tsat ~ 1.90 K ~21 mbar

HX side @ middle of the module

50

HX side @ connecting pipe

45

Magnet side @ connecting pipe

40

Magnet simulator pipe @ middle

35

30

T-Tsat (mK)

25

20

15

10

5

0

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Power applied (W/m)

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

dt vs heat load t sat 2 00 k 32 mbar
DT vs. heat load - Tsat ~ 2.00 K ~32 mbar

HX side @ middle of the module

HX side @ connecting pipe

Magnet side @ connecting pipe

Magnet simulator pipe @ middle

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

prediction for lhc high luminosity conditions
Prediction for LHC high luminosity conditions

Magnet simulator side

HX side

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

conclusions
Conclusions
  • More than 50 heat load configurations were measured

http://www-bdcryo.fnal.gov/darve/heat_exchanger/instrumentation.html

  • The temperature rise at nominal LHC luminosity conditions

will not exceed 50 mK.

  • Validation of the theoretical model.
  • The wetted area of the heat exchanger tube is about 22 %.
  • Need to increase of the connecting pipe diameter in order to reduce the temperature rise resulting from the possible LHC ultimate luminosity conditions.

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET

acknowledgement
Acknowledgement

This work was supported by the US Department of Energy.

We would like to thank the LHC/ACR, LHC/ECR, LHC/CRI groups and in particular the support of R. Losserand-Madoux, A. Bezaguet, E. Fernandez, C. Masure,

B. Vullierme, L. Herblin, S. Pelletier, JB Bart, B. Beauquis, D. Tobias, M. Gautier, C. Berthelier and R. Vuillermet.

He II HEAT EXCHANGER TEST UNIT FOR THE LHC INNER TRIPLET