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

DISTRIBUTED CRYOGENIC COOLING WITH

MINIATURIZED FLUID CIRCUITS

Steffen Grohmann, ETT/TT

RD39 Collaboration

ST Workshop 2003

CERN, April 01-03, 2003

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


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/


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


DETECTOR MODULE DESIGN

StripDetector

Support

PitchAdapter

APV25

Hybrid

CoolingPipe

Spacer

Module for thermal andthermo-elastic tests Blanca Perea Solano


COOLING POWER DISTRIBUTION

Cooling Power Distribution Methods

ConvectionConduction Radiation

Single-phase Two-phase

ForcedCirculation

NaturalCirculation

Solid (Liquid)Conductor

ColdPump

WarmCompressor

Thermo-syphon

HeatPipe (Shielding)


MINIATURE CRYOGENIC FLUID CIRCUIT Layout


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: 15 ml/min Argon

Typical microtube diameters:supply and return lines 1 mmexternal tube of transfer lines 2 mmevaporator heat exchangers 100-500 m

Fluid Tnb [K] Vrel [ml/min]

Methane 111.7 0.28

Argon 87.3 0.27

Nitrogen 77.3 0.37

Neon 27.1 0.58

Hydrogen 20.3 1.90

Helium 4.2 23.23


CRYOGENIC MICROPUMP

Prototype

• Variable speed control from 0-6000 min-1

• Flow rates compatible with cooling powers in the range of 10-100 W

Assembly Prototype


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


CRYOGENIC MICROPUMP

Performance

Time [hh:mm]

00:00 00:10 00:20 00:30 00:40 00:50 01:00

Pres

sure

Hea

d [m

bar]

0

2000

4000

6000

8000Pu

mp

Spee

d [1

/min

]

Pump Speed

Pressure Head

Flow Rate:

Operation with liquid Argon at 120 K


HEAT TRANSFER IN MICROTUBES

Problem

FliWii TTA

Q

,

Indirect method to measure T!

Microtubes of 120, 250 and 500 microns inner diameter

Heat Transfer Coefficient


TEST STAND


EXPERIMENTAL SETUP

Circuit Layout


MICROTUBE CIRCUIT


HTC MEASUREMENT IN MICROTUBES

Concept


THERMAL RESISTANCE OF THE HEAT EXCHANGER

TiH

i

ihxi

ihxi

KL

dHH

d

ARARRk i

3

2

4.010

i

1Pr2ReNu

Nu

11

0.0E+00

4.0E-05

8.0E-05

1.2E-04

1.6E-04

2.0E-04

0 2000 4000 6000 8000 10000 12000

Re [-]

1/k

i [m

2 K/W

]

Experimental Data

Fit with Hausen-type Equation*

Heat Exchanger Thermal Resistance:Rhx = 0.838 ± 0.003 K/W

*)max. error: 0.5%

Example: di 250 microns

Measurement of the effective thermal resistance Rhx of the heat exchanger by fitting

a model for single-phase turbulent heat transfer (Hausen-type Equation)


SINGLE-PHASE HEAT TRANSFER

Turbulent Flow – Liquid

0

10000

20000

30000

40000

0 2000 4000 6000 8000 10000 12000

Re [-]

i [W

/m2 K

]

Experimental Data

Fitting *)

Macroscale Correlation

*)max. error: 0.5%

0

10000

20000

30000

40000

0 2000 4000 6000 8000 10000 12000

Re [-]

i [W

/m2 K

]

Experimental Data

Fitting *)

Macroscale Correlation

*)max. error: 0.2%

di 250 microns di 500 microns

Preliminary Results

Fluid: liquid Argon at 120 K


HEAT TRANSFER MEASUREMENTS

Real Diameter

di = 210 ± 10 m


thermal conductivity thermal dilatation thermo-elasticity

cooling power generation heat transfer complexity

Physical, Mechanical and Thermal Impact

SUMMARY OF DESIGN ISSUES

RequirementsHeat Load, Temperature, Operating- and Local Conditions

Design of the DeviceThermo-mechanical Design

Cooling System DesignProcess

InterfaceHeat Exchanger

Temperature Difference

and Pressure Drop

Vacuum

Control

Integrated Design!


distributed cooling over long distances (several meters) with low losses

mechanical and acoustic decoupling of heat sources and heat sink

minimization of the heat leakin 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


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


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!

Documents

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