1. DISTRIBUTED CRYOGENIC COOLING WITH MINIATURIZED FLUID CIRCUITS Steffen Grohmann, ETT/TT RD39 Collaboration ST Workshop 2003 CERN, April 01-03, 2003

2. ST WORKSHOP 2003  02 APRIL 2003  CERN O U T L I N E  Introduction  CERN RD39 Collaboration - Cryogenic Tracking Detectors  Detector Development for Luminosity Measurement at the LHC  Development of a Miniature Cryogenic Fluid Circuit  Circuit Layout and Features  Cryogenic Micropump Development  Heat Transfer in Microtubes  Experimental Setup Concept of Measurement  Preliminary Results  Advantages of Cryogenic Microtube Circuits  Applications and Trends

3. ST WORKSHOP 2003  02 APRIL 2003  CERN CERN RD39 COLLABORATION Organization:18 institutes with 54 collaborators Goals:  improvement of the radiation hardness of Si detectors by a factor of 10 or more  development of segmented Si detectors with faster signal and higher signal-to-noise ratio  fundamental device physics of sensors in a wide temperature range  development of low-mass cryogenic systems and low-temperature electronics for HEP How?increase of the Charge Collection Efficiency by manipulating the charge state of radiation induced deep defect levels and by changing the properties of radiation induced traps:  temperature (130 K)  injection of charge (forward biased junction, light) More:http://rd39.web.cern.ch/RD39/

4. ST WORKSHOP 2003  02 APRIL 2003  CERN DETECTOR DEVELOPMENT FOR THE LHC Cooling Requirements: 4 silicon microstrip detector modules operated at 130 K 3 W power dissipation per module overall cooling power per station: 20 W @ 130 K Cooling Concept: autonomous cooling system for each station central cryocooler as a cold source fluid circuit for cooling power distribution 

5. ST WORKSHOP 2003  02 APRIL 2003  CERN DETECTOR MODULE DESIGN Strip Detector Support Pitch Adapter APV25 Hybrid Cooling Pipe Spacer Module for thermal and thermo-elastic tests Blanca Perea Solano

6. ST WORKSHOP 2003  02 APRIL 2003  CERN COOLING POWER DISTRIBUTION

7. ST WORKSHOP 2003  02 APRIL 2003  CERN MINIATURE CRYOGENIC FLUID CIRCUIT Layout

8. ST WORKSHOP 2003  02 APRIL 2003  CERN FLUID CIRCUIT Features  Flow rates of cryogenic working fluids per watt cooling power, saturated liquid at normal boiling point, dry evaporation:  Roman pot station with  x = 0.5, 20 W @ 120 K:15ml/min Argon  Typical microtube diameters:  supply and return lines1mm  external tube of transfer lines 2mm  evaporator heat exchangers 100-500  m FluidT nb [K]V rel [ml/min] Methane111.70.28 Argon87.30.27 Nitrogen77.30.37 Neon27.10.58 Hydrogen20.31.90 Helium4.223.23

9. ST WORKSHOP 2003  02 APRIL 2003  CERN CRYOGENIC MICROPUMP Prototype Variable speed control from 0-6000 min -1 Flow rates compatible with cooling powers in the range of 10-100 W AssemblyPrototype

10. ST WORKSHOP 2003  02 APRIL 2003  CERN CRYOGENIC MICROPUMP Pumping Principle Consistent material composition to solve problem of thermal dilatation Micro annular gear pump Positional and shape tolerances on the micron level  micro manufacturing technologies Tungsten carbide for operation with non-lubricating fluids and high resistance to wear

11. ST WORKSHOP 2003  02 APRIL 2003  CERN CRYOGENIC MICROPUMP Performance Operation with liquid Argon at 120 K

12. ST WORKSHOP 2003  02 APRIL 2003  CERN HEAT TRANSFER IN MICROTUBES Problem  Indirect method to measure  T! Microtubes of  120, 250 and 500 microns inner diameter Heat Transfer Coefficient

13. ST WORKSHOP 2003  02 APRIL 2003  CERN TEST STAND

14. ST WORKSHOP 2003  02 APRIL 2003  CERN EXPERIMENTAL SETUP Circuit Layout

15. ST WORKSHOP 2003  02 APRIL 2003  CERN MICROTUBE CIRCUIT

16. ST WORKSHOP 2003  02 APRIL 2003  CERN HTC MEASUREMENT IN MICROTUBES Concept

17. ST WORKSHOP 2003  02 APRIL 2003  CERN THERMAL RESISTANCE OF THE HEAT EXCHANGER Example: d i  250 microns Measurement of the effective thermal resistance R hx of the heat exchanger by fitting a model for single-phase turbulent heat transfer (Hausen-type Equation)

18. ST WORKSHOP 2003  02 APRIL 2003  CERN SINGLE-PHASE HEAT TRANSFER Turbulent Flow – Liquid d i  250 micronsd i  500 microns Preliminary Results Fluid: liquid Argon at 120 K

19. ST WORKSHOP 2003  02 APRIL 2003  CERN HEAT TRANSFER MEASUREMENTSReal Diameter d i = 210 ± 10  m

20. ST WORKSHOP 2003  02 APRIL 2003  CERN  thermal conductivity  thermal dilatation  thermo-elasticity  cooling power generation  heat transfer  complexity Physical, Mechanical and Thermal Impact SUMMARY OF DESIGN ISSUES Requirements Heat Load, Temperature, Operating- and Local Conditions Design of the Device Thermo-mechanical Design Cooling System Design Process Interface Heat Exchanger Temperature Difference and Pressure Drop Vacuum Control Integrated Design!

21. ST WORKSHOP 2003  02 APRIL 2003  CERN distributed cooling over long distances (several meters) with low losses mechanical and acoustic decoupling of heat sources and heat sink minimization of the heat leak in transfer lines minimized stress due to cooling pipe connections heat absorption very close to the source of heat very large HTCs and cooling power density in miniature heat exchangers CRYOGENIC MICROTUBE CIRCUITS Advantages precise control of temperature and flow rate fully hermetic, oil- and contamination-free

22. ST WORKSHOP 2003  02 APRIL 2003  CERN APPLICATIONS  Detector and electronics cooling  HEP  Computing (cryo-acceleration)  Instrument cooling in cryosurgery  Others…  Applications in super-conductor technology  Passive magnet bearings e.g. for centrifuges, flywheels, motors, generators  Current limiters  Transformers  Motors 10-100 W 100-1000 W

23. ST WORKSHOP 2003  02 APRIL 2003  CERN Process  (miniature fluid circuits) (Joule-Thomson?) (refrigerant mixtures?) Cryocooler  pulse tube Power  growing power densities (electronics) Heat exchange  miniaturization Process  (miniature fluid circuits) (Joule-Thomson?) (refrigerant mixtures?) Cryocooler  pulse tube Power  growing power densities (electronics) Heat exchange  miniaturization TRENDS Cryogenic applications require integrated R&D of several disciplines. Cooling is a major design issue!